WO2023079850A1

WO2023079850A1 - Method for determining conformity of rolling mill roller, method for rolling metal strip, and method for producing cold-rolled steel sheet

Info

Publication number: WO2023079850A1
Application number: PCT/JP2022/034960
Authority: WO
Inventors: 渉馬場; 佑馬下司; 利行坂元; 由紀雄高嶋
Original assignee: Ｊｆｅスチール株式会社
Priority date: 2021-11-02
Filing date: 2022-09-20
Publication date: 2023-05-11

Abstract

Provided is a method for determining the conformity of a rolling mill roller which makes it possible to estimate online the state of polygonal wear of a roller to be evaluated which is caused by rolling, and to prevent light chatter marks. This method for determining the conformity of a rolling mill roller includes: a rolling load data acquisition step (step S3) for acquiring rolling load operation data of a stand (F1-F5) which is the roller to be evaluated; a circumferential speed data acquisition step (step S4) for acquiring circumferential speed operation data for the roller to be evaluated; a vibration analysis step (step S5) for analyzing the vibration behavior of the stand (F1-F5) by using the rolling load operation data of the stand (F1-F5); a surface shape estimation step (step S6) for estimating the surface shape of the roller to be evaluated during the rolling of the metal strip on the basis of the analysis results about the vibration behavior of the stand (F1-F5) and the circumferential speed operation data for the roller to be evaluated; and a conformity determination step (step S7) for determining the conformity of the roller to be evaluated on the basis of the surface shape of the roller to be evaluated.

Description

Method for judging suitability of rolling rolls, method for rolling metal strip, and method for manufacturing cold-rolled steel sheet

The present invention relates to a method for judging suitability of rolling rolls, a method for rolling metal strips, and a method for manufacturing cold-rolled steel sheets.

Metal strips such as steel sheets used in automobiles, beverage cans, etc. are made into products after undergoing continuous casting, hot rolling, and cold rolling processes, followed by annealing and plating processes. Among these, the cold rolling process is the final process for determining the thickness of the metal strip as a product. In recent years, the thickness of the plating may be thinner than before, and the surface texture of the metal strip before the plating process tends to affect the surface texture of the product after the plating process, so it is necessary to prevent the occurrence of surface defects. increasing.

Chatter marks are one of the surface defects that occur during the cold rolling process. This is a linear mark that appears in the width direction of the metal band, and is a surface defect in which such linear marks periodically appear in the longitudinal direction of the metal band. Chatter marks are said to be caused by vibrations of the rolling mill (hereinafter referred to as chattering). Here, a very light chatter mark may not be found by visual inspection or plate thickness measurement after the cold rolling process, and may be recognized only after the plating process. For this reason, it is not noticed that a large number of surface defects have occurred during this period, and as a result, the yield of the product is lowered, which is a factor in significantly impeding productivity. In addition, in the case of thin materials such as steel sheets for cans and electrical steel sheets, sudden changes in the thickness and tension of the metal strips due to chattering may cause production troubles such as breakage of the metal strips, which may hinder productivity.

Against this background, conventionally, there have been proposed methods for suppressing the occurrence of chattering, such as those disclosed in Patent Documents 1 to 3 and Non-Patent Document 1, for example.
In the method for detecting chattering of a rolling mill shown in Patent Document 1, a vibration detector is installed in one or more parts of each part of the rolling mill to detect the vibration of each part of the rolling mill during operation, and the vibration detected by each part of the rolling mill is detected. It detects chattering. In this rolling mill chattering detection method, the mill's natural frequency, gear engagement failure, bearing failure, coupling play between the spindle and roll, and roll flaws are each calculated to generate chatter marks. The fundamental frequency for each cause of occurrence. Then, the vibration displacement, vibration velocity, or vibration acceleration of each part is detected, and frequency analysis is performed on the detected vibration displacement, vibration velocity, or vibration acceleration of each part. In addition, frequency analysis of rolling parameters such as tension, rolling torque, rolling speed, rolling load, and strip thickness variation is performed. Then, when the results of frequency analysis of the measured values of vibration and rolling parameters exceed the set values at frequencies that are integral multiples of the fundamental frequency for each cause of chatter mark occurrence, it is determined that chattering has occurred, and the cause of the occurrence is determined as described above. is specified from the fundamental frequency of

Also, the vibration abnormality detection method in cold rolling or temper rolling shown in Patent Document 2 has a vibration signal collection step, an FFT frequency analysis step, and a vibration abnormality determination step. In the vibration signal collecting step, vibration signals detected by at least one small diameter roll among the small diameter rolls between the stands of the cold rolling mill or on the entry and exit sides of the cold rolling mill are collected. In the FFT frequency analysis step, the frequency analysis of the collected vibration signal is performed using the fast Fourier transform method to obtain the frequency components contained in the vibration signal and their spectral values. Further, in the vibration abnormality determination step, among the frequency components obtained in the FFT frequency analysis execution step, at least a plurality of spectrum values of frequency components that are the same as the frequency of string vibration in a plurality of vibration modes of the steel plate calculated by a predetermined expression. If one exceeds a preset threshold, it is determined that there is vibration abnormality.

In addition, the method for preventing chatter marks on a steel plate disclosed in Patent Document 3, when cold-rolling a steel plate having a yield strength of 450 MPa or less after hot rolling and pickling, the natural frequency of the cold rolling mill, The chord length between the final stand of the cold rolling mill and the small-diameter roll that first contacts the steel sheet on the delivery side of the cold rolling mill, as shown in the predetermined formula, is set so that the frequency of the chordal vibration of the steel sheet does not match. . In addition, the bending strain generated on the surface of the steel sheet, which is expressed by the predetermined formula, is set to a magnitude that does not cause plastic deformation of the steel sheet.

Furthermore, Non-Patent Document 1 describes an analysis of the "chattering" phenomenon in cold rolling of ultra-thin steel sheets. Non-Patent Document 1 describes the chattering phenomenon that occurs during the rolling of ultra-thin cold-rolled steel sheets with a total cold reduction of 93 to 94%. The results of research that examined the

Japanese Patent No. 2964887 Japanese Patent No. 6296046 Japanese Patent No. 6102835

By the way, in the conventional techniques shown in these Patent Documents 1 to 3 and Non-Patent Document 1, vibrometers (accelerometers, etc.) are installed at a plurality of locations in the rolling mill to monitor the vibration behavior during rolling. , early detection of chattering has been performed.
However, among the chatter marks, mild chatter marks that are difficult to detect only by vibration measurement of the rolling mill may occur. A slight chatter mark is when unevenness with an amplitude of about 0.1 to 5 μm is formed on the surface of the metal strip. may not be recognized for the first time after the plating process. For this reason, it is not noticed that a large number of surface defects have occurred during this period, and as a result, the yield of the product is lowered, which is a factor in significantly impeding productivity.

On the other hand, it is known that chatter marks, including these mild chatter marks, are caused by polygonal wear, in which the circumferential profile of the surface of the rolling rolls during rolling becomes polygonal. Polygonal wear means that the surface shape of the roll becomes polygonal due to the growth of minute irregularities on the surface of the roll during the rolling process of the metal strip and the growth of irregularities with a specific pitch.

Therefore, the present invention has been made to solve this conventional problem, and its purpose is to estimate the state of polygonal wear of a roll to be evaluated that occurs during rolling on-line, It is an object of the present invention to provide a method for judging suitability of rolling rolls, a method for rolling a metal strip, and a method for manufacturing a cold-rolled steel sheet, which can prevent chatter marks.

In order to solve the above problems, a method for determining suitability of rolling rolls according to an aspect of the present invention is a rolling mill comprising one or a plurality of stands each having a plurality of rolling rolls. A rolling load data acquisition method for determining the suitability of a roll to be evaluated, which is a rolling roll arbitrarily selected from rolling rolls, wherein rolling load data is obtained for a stand having the roll to be evaluated. A step, a peripheral speed data acquisition step of acquiring operation data of the peripheral speed of the roll to be evaluated, and a stand with the roll to be evaluated using the operation data of the rolling load of the stand with the roll to be evaluated acquired in the rolling load data acquisition step A vibration analysis step for analyzing the vibration behavior of, the analysis result of the vibration behavior of the stand having the evaluation target roll by the vibration analysis step, and the peripheral speed operation data of the evaluation target roll acquired in the peripheral speed data acquisition step. Based on the surface shape estimation step of estimating the surface shape of the evaluation target roll from the rolling of the metal strip, and the surface shape of the evaluation target roll estimated by the surface shape estimation step, the suitability of the evaluation target roll is determined. and a conformity determination step.

Further, in a method for rolling a metal strip according to another aspect of the present invention, the suitability determination of the evaluation target roll is performed during rolling of the metal strip using the above-described method for determining suitability of the rolling rolls, and the result of the suitability determination is unsuitable. In this case, the roll to be evaluated is replaced with a new rolling roll to roll the metal strip.

A gist of a method for manufacturing a cold-rolled steel sheet according to another aspect of the present invention is to manufacture a cold-rolled steel sheet using the metal strip rolling method described above.

According to the method for determining suitability of rolling rolls, the method for rolling a metal strip, and the method for manufacturing a cold-rolled steel sheet according to the present invention, the state of polygonal wear of an evaluation target roll that occurs during rolling is estimated online, and polygonal wear is used. Minor chatter marks can be prevented.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic configuration diagram of a rolling mill to which a rolling roll suitability determination method according to an embodiment of the present invention is applied; It shows the specific shape of the rolling rolls, and (a) is an explanation in which the cross-sectional shape (solid line) of the rolling roll is plotted along with the reference circle (dashed line) when it is assumed that the cross-sectional shape of the rolling roll is a perfect circle. FIG. (b) is a graph showing an example of the relationship between the circumferential position (angle) of the rolling rolls and the amount of radial deviation of the cross-sectional shape from the perfect circle represented by the diameter of the rolling rolls. . 4 is a graph showing an example of the relationship between the unevenness pitch of the surface of the rolling roll and the spectrum value. It is a schematic diagram which shows a mode that a rolling roll is installed in a roll grinder and the surface shape of a rolling roll is measured. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic configuration diagram of a rolling mill in which each stand is provided with a conformity determination device to which a method for determining conformity of rolling rolls according to an embodiment of the present invention is applied; However, FIG. 5 shows a state in which the rolling roll suitability determination device is provided only in the first stand F1. 6 is a flow chart for explaining the flow of processing in the high-level computer of the rolling mill and the suitability determination device shown in FIG. 5; FIG. 4 is a diagram for explaining a rolling mill vibration model in which a four-stage stand is approximated by a mass-spring system; In a rolling mill vibration model that approximates a four-stage stand with a mass-spring system, when the upper work roll is selected as the roll to be evaluated, the coupling with the upper backup roll is virtually released to calculate the frequency response. FIG. 10 is a diagram for explaining an example of In a rolling mill vibration model that approximates a four-stage stand with a mass-spring system, when the upper work roll is selected as the roll to be evaluated, the coupling with the lower work roll is virtually released to estimate the frequency response. It is a figure for demonstrating the example to calculate. FIG. 4 is a diagram for explaining a rolling mill vibration model in which a six-stage stand is approximated by a mass-spring system; FIG. 5 is a diagram for explaining an example of calculating a frequency response when an upper intermediate roll is selected as an evaluation target roll in a rolling mill vibration model in which a six-high stand is approximated by a mass-spring system; FIG. 5 is a diagram for explaining an example of calculating a frequency response when an upper intermediate roll is selected as an evaluation target roll in a rolling mill vibration model in which a six-high stand is approximated by a mass-spring system; FIG. 6 is a graph showing changes in the peripheral speed of the rolling rolls and timing for judging suitability of rolls to be evaluated when a metal strip is continuously rolled using the rolling mill shown in FIG. 5 ; FIG.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings. Here, the drawings are schematic. Therefore, it should be noted that the relationship, ratio, etc. between the thickness and the planar dimensions are different from the actual ones, and the drawings include portions where the relationship and ratio of the dimensions are different from each other.
Further, the embodiments shown below are examples of devices and methods for embodying the technical idea of the present invention. etc. are not specified in the following embodiments.

First, in FIG. 1, abnormal vibrations of the stands F1 to F5 of the rolling mill a that occur during rolling of the metal strip S are called chattering, and periodic patterns formed on the surface of the metal strip S by chattering are called chatter marks. call. In the suitability determination device 30 (see FIG. 5) to which the rolling roll suitability determination method according to the present embodiment is applied, chatter marks, in which irregularities with an amplitude of about 0.1 to 5 μm are formed on the surface of the metal strip S, A suitability determination is performed for a roll to be evaluated (which will be described later in detail) targeting so-called mild chatter marks. This slight chatter mark is often caused by the thickness of the metal strip S varying. It is often difficult to detect a slight chatter mark formed by minute irregularities with the plate thickness gauge 7 installed on the delivery side of the rolling mill a. Moreover, it is difficult to make a determination even by visually observing the surface of the metal strip S after rolling. In many cases, mild chatter marks are detected after surface treatment such as plating is performed, or are detected for the first time after the metal strip S is press-formed.

Chattering, which causes chatter marks, is said to be often caused by looseness in bearings, gear engagement, couplings, etc. that make up the rolling mill. In this case, chattering is conventionally detected by analyzing vibration data obtained from vibrometers 5 installed in the respective stands F1 to F5 of the rolling mill a, and determining the magnitude of vibration in a specific frequency band as a preset threshold value. was considered to be detectable when the However, the inventors of the present invention have found that some slight chatter marks are difficult to detect with the vibrometers 5 installed in the stands F1 to F5 of the rolling mill a or their peripheral equipment. Furthermore, during the rolling process of the metal strip S, fine irregularities are generated on the surface of the rolling rolls, and irregularities with a specific pitch grow, thereby polygonalizing the surface shape of the rolling rolls (causing polygonal wear). I have found that there is a case. Upper and lower work rolls 1, upper and lower backup rolls 2, and upper and lower intermediate rolls 3 are called mill rolls 1, 2, 3, respectively. In this case, during the rolling of the metal strip S, the vibrations of the stands F1 to F5 of the rolling mill a gradually increase, resulting in chattering. Therefore, it is important to estimate the change in the surface shape of the roll to be evaluated.

(rolling mill)
FIG. 1 shows a schematic configuration of a rolling mill to which a rolling roll suitability determination method according to an embodiment of the present invention is applied.
The rolling mill a shown in FIG. 1 is a cold rolling mill, and includes a plurality of stands for cold rolling a steel sheet as the metal strip S (in this embodiment, from the first stand F1 counted from the entry side in the sheet threading direction A tandem mill with a fifth stand F5). Other devices attached to the rolling mill a (for example, an entry-side rewinder, a welder, a looper, an exit-side cutter, a winder, etc.) are omitted from the drawing.
Here, the first stand F1 to the fourth stand F4 counted from the entry side in the threading direction are four-stage stands, and the fifth stand F5 counted from the entry side is a six-stage stand. there is

Each of the four-stage stands F1 to F4 includes, in a housing 4, upper and lower work rolls 1 for rolling a steel plate as the metal strip S, and an upper side for supporting the upper and lower work rolls 1, respectively. and a backup roll 2 on the lower side. In addition, the six-stage stand F5 includes, in the housing 4, upper and lower work rolls 1, upper and lower backup rolls 2, upper intermediate rolls 3, and lower intermediate rolls 3. I have. The upper and lower work rolls 1 roll a steel sheet as a metal strip S. Upper and lower backup rolls 2 support upper and lower work rolls 1, respectively. An upper intermediate roll 3 is arranged between the upper work roll 1 and the upper backup roll 2 . A lower intermediate roll 3 is arranged between the lower work roll 1 and the lower backup roll 2 .

Vibrometers 5 for measuring vibrations of the stands F1 to F5 are installed on the upper portions of the housings 4 of the stands F1 to F5. The vibration meter 5 is preferably a piezoelectric element type vibration sensor, but may be a vibration meter of another type.
A rolling load detector 6 for detecting the rolling load of each stand F1 to F5 is installed above the backup roll 2 above each stand F1 to F5. The rolling load detector 6 is composed of a load cell.
A tension meter for detecting the tension of the steel sheet as the metal strip S is provided on the tension meter roll 8 provided between the adjacent stands F1 to F5. Further, a plate thickness meter 7 for detecting the plate thickness of the steel plate as the metal strip S is installed on the delivery side of each of the first stand F1 and the fifth stand F5.

A work roll driving device 9 is connected to the upper and lower work rolls 1 of each of the stands F1 to F5, and the work roll driving device 9 controls the peripheral speed of the upper and lower work rolls 1. A roll speed controller 11 is connected. The roll speed controller 11 is provided with roll rotation speed detectors (not shown) for detecting the rotation speeds of the upper and lower work rolls 1 . Further, the upper and lower work rolls 1 of each of the stands F1 to F5 are provided with roll gap controllers 10 for controlling the roll gaps between the upper and lower work rolls 1. As shown in FIG. The roll gap controller 10 is provided with a roll-down position detector (not shown) for detecting roll-down positions of the upper and lower work rolls 1 .

Each stand F1 to F5 of the rolling mill a is provided with a roll changer (not shown). The roll changer is provided with a carriage (not shown) capable of traveling on rails (not shown) in the axial direction of the rolling rolls 1, 2 and 3. As shown in FIG. The carriage moves to the vicinity of the rolling rolls 1, 2, 3 to be replaced under instructions from the host computer 14, which will be described later. The operator removes the used rolling

rolls

1, 2 and 3 from the predetermined stands F1 to F5, and then loads new rolling rolls after grinding into the predetermined stands F1 to F5. The used rolling rolls 1, 2 and 3 are transported to a roll shop and regrinded.

Here, the system for manufacturing steel products is composed of a large-scale hierarchical system for production management targeting a large number of facilities. Specifically, the hierarchical system includes a host computer 14 at Level 3 at the highest level, a control computer 13 at Level 2 for each production line such as a continuous cold rolling mill, and a control computer 13 for each facility constituting each line is configured in a hierarchy such as the control controller 12 of Level1. The host computer 14 is a business computer, the control computer 13 is a process computer, and the control controller 12 is a PLC.

The control computer 13 is connected between the host computer 14 and the subordinate controller 12, receives the manufacturing plan planned by the host computer 14, and instructs the manufacturing line to manufacture the steel sheet as the metal strip S. . In addition, the control computer 13 collects various performance information from the control controller 12, displays them on the operation monitoring screen, performs calculations based on a theoretical model, and transmits information necessary for control to the control controller 12. Its main role is to send On the other hand, the control controller 12 issues instructions to the drives, valves, sensors, etc. that make up the manufacturing equipment at appropriate timing, adjusts operations so that the devices do not interfere with each other, and counts values held by the sensors. The main role is to operate by linking with physical information.

In this embodiment, the control computer 13 determines the rolling operation conditions for the next steel sheet before the welding point of the steel sheet as the metal strip S passes. Specifically, a pass schedule is set according to information such as base material dimensions (base material plate thickness and width) and product target plate thickness given from the host computer 14. Determine the predicted values of the rolling load and advance rate, and the set values of the roll gap and roll peripheral speed. At that time, in order to set the rolling load and roll peripheral speed, as information on the rolling rolls 1, 2, and 3 used in each stand F1 to F5, the actual measurement of the roll diameter after grinding (before charging into the stand) The specification information of the rolling rolls including the values is sent from the host computer 14 to the control computer 13 . The specification information of the rolling rolls includes roll diameter, roll barrel length, roll number, roll material, surface roughness standard classification, and the like.

The control controller 12 controls the roll speed controller 11 of each stand F1 to F5 and the roll gap control of each stand F1 to F5 based on the set values (command values) of the roll gap and the roll peripheral speed obtained from the control computer 13. A process for controlling the machine 10 is executed. Further, the control controller 12 collects the rolling load of each stand F1 to F5 detected by the rolling load detector 6 from the rolling load detectors 6 installed in each of the stands F1 to F5. The control controller 12 also collects measured values of the rotational speeds of the upper and lower work rolls 1 from the rotational speed detectors of the roll speed controller 11 . Furthermore, the control controller 12 continuously collects rolling data such as tension measurements by the tension meter provided on the tension meter roll 8 . Then, the control controller 12 outputs these rolling data to the control computer 13 at preset intervals.

(Conformity determination device for rolling rolls)
In the present embodiment, as shown in FIG. 5, each of the rolling stands F1 to F5 is provided with a rolling roll suitability determination device 30 for determining suitability of the roll to be evaluated. FIG. 5 shows a state in which the rolling roll suitability determination device 30 is provided only in the first stand F1. This suitability determination device 30 estimates on-line the surface shape of the evaluation target roll that occurs during rolling, that is, the state of polygonal wear. Then, the suitability determination device 30 determines suitability of the roll to be evaluated based on the estimated surface shape of the roll to be evaluated, that is, the state of polygonal wear, and prevents mild chatter marks caused by polygonal wear. be.

Here, the roll to be evaluated is a rolling roll arbitrarily selected from a plurality of rolling

rolls

1, 2, and 3 of arbitrary stands F1 to F5 among the stands F1 to F5. The upper and lower work rolls 1, the upper and lower backup rolls 2, and the upper and lower intermediate rolls 3 are called mill rolls, respectively. In the case of four-stage stands F1 to F4, the rolls selected arbitrarily from the upper and lower work rolls 1 and the upper and lower backup rolls 2 of any stand F1 to F4 are evaluated. called a roll. In the case of a six-tier stand F5, mill rolls arbitrarily selected from the upper and lower work rolls 1, the upper and lower backup rolls 2, and the upper and lower intermediate rolls 3 of the stand F5. is called an evaluation target role.

The surface shape of the rolling rolls (rolls to be evaluated) 1, 2, 3 refers to the cross-sectional shape of the trunk portions of the rolling rolls 1, 2, 3. Since the cross-sectional shapes of the rolling rolls 1, 2, and 3 are generally circular, the surface shape is represented by the deviation of the cross-sectional shape from a perfect circle. The cross sections of the rolling rolls 1, 2, and 3 may be any cross section in the axial direction of the body, but preferably the cross section at the center position of the body.

A specific example of the surface shape of the rolling rolls 1, 2, and 3 is shown in FIG. FIG. 2(a) plots the cross-sectional shapes (solid lines) of the rolling rolls 1, 2, and 3 together with the reference circles (broken lines) when the cross-sectional shapes of the rolling rolls 1, 2, and 3 are assumed to be perfect circles. It is. In addition, FIG. 2(b) shows the cross-sectional shape from the perfect circle represented by the diameter of the

rolls

1, 2, 3, with the positions (angles) of the

rolls

1, 2, 3 in the circumferential direction as the horizontal axis. It is a figure which represented the deviation amount (deviation amount) of a radial direction as a vertical axis|shaft. The surface shapes of the rolling rolls (evaluation rolls) 1, 2, and 3 to be estimated in the present embodiment are as shown in FIG. This information is specified by the relationship with the size of unevenness on the surface. The diameters of the rolling rolls (evaluation target rolls) 1, 2, and 3, which serve as a reference when specifying the perfect circle, are measured during grinding of the rolling rolls (evaluation target rolls) 1, 2, and 3, and are stored in the host computer 14. Saved by the operator.

On the other hand, the surface shapes of the rolling rolls (evaluation target rolls) 1, 2, and 3 to be estimated in the present embodiment are not information specified by continuous curves as shown in FIGS. may For example, the surfaces of the rolling rolls (evaluation target rolls) 1, 2, and 3 are equally divided in the circumferential direction and the outer diameters are measured at opposing positions, and the maximum and minimum diameters of them are Dmax and Dmin, respectively. Dmax-Dmin may be used as the surface shape information of the rolling rolls (evaluation target rolls) 1, 2, and 3. The number of equal divisions in the circumferential direction is 4 to 36000 equal divisions, more preferably 360 equal divisions or more.

Furthermore, as the surface shape of the rolling rolls (evaluation target rolls) 1, 2, 3, in addition to the above, the cross-sectional shape related to the pitch of the unevenness formed on the rolling rolls (evaluation target rolls) 1, 2, 3 information. On the rolling rolls (evaluation target rolls) 1, 2, and 3 incorporated in each of the stands F1 to F5, an uneven shape in which a plurality of frequency components are combined is formed in relation to the vibration of each of the rolling stands F1 to F5. may occur. In this case, the relationship between the circumferential position information (angle information) of the rolling rolls (evaluation target rolls) 1, 2, and 3 and the amount of deviation from the perfect circle is subjected to frequency analysis using the fast Fourier transform method. Then, the relationship between the pitch of the unevenness corresponding to the frequency component included in the surface shape and the spectrum value corresponding to the pitch may be used as the surface shape of (evaluation target rolls) 1, 2, and 3. FIG. 3 shows the unevenness of the surface of the rolling rolls obtained by the frequency analysis of the fast Fourier transform method from the relationship between the position information of the rolling rolls (rolls to be evaluated) 1, 2, and 3 in the circumferential direction and the amount of deviation from the perfect circle. It is an example showing the relationship between pitch and spectrum value.

As the surface shape of the rolling rolls (evaluation target rolls) 1, 2, and 3 to be estimated in this embodiment, amplitude information associated with the pitch of the unevenness formed on the surface of the evaluation target roll, as will be described later. and The amplitude information is the difference between the maximum value and the minimum value of the deviation amount from the perfect circle as the cross-sectional shape of the rolling rolls (evaluation target rolls) 1, 2, 3 per pitch. Further, the amplitude information associated with the pitch of the unevenness is amplitude information when the pitch of the unevenness is set in advance and the pitch is set as one cycle. For example, the relationship between the position (angle) in the circumferential direction of the roll to be evaluated and the amount of deviation from the perfect circle of the cross-sectional shape is expanded into a Fourier series, and the resulting Fourier coefficient is defined as amplitude information related to the pitch. You can also This is because it is an index representing the amplitude corresponding to a specific pitch or frequency.

As a method for measuring the surface shape of the rolling rolls (rolls to be evaluated) 1, 2, and 3, for example, measurement using a roll grinder is possible. FIG. 4 schematically shows how a rolling roll is installed in a roll grinder and the surface profile is measured. When measuring the surface shape of the rolling rolls (evaluation target rolls) 1 , 2 and 3 , the rests 22 support both ends of the rolling rolls (evaluation target rolls) 1 , 2 and 3 in the axial direction. In this state, one axial end of the rolling rolls 1, 2, 3 is fixed by the chuck 21 of the roll rotating device 23, and the other axial end of the rolling rolls 1, 2, 3 is axially rotated by the tailstock 24. impose. Displacement gauges 26 are installed on the surfaces of the body portions of the rolling rolls 1, 2 and 3 so as to be in contact with the surfaces of the body portions of the rolling rolls 1, 2 and 3 and detect the displacement of the surfaces. Any contact or non-contact measuring device can be used as the displacement meter 26 . For this displacement meter 26, it is preferable to use, for example, a contact-type magnescale with relatively high measurement accuracy. It is preferable to use a Magnescale with a measurement accuracy of about 0.1 to 0.2 μm, a measurement stroke of about 1 to 5 mm, and a sampling frequency of about 1 kHz. Then, the rolling rolls 1, 2, 3 are rotated at a low speed (for example, 5 to 10 rpm) by a roll rotating device 23 whose rotating shaft is connected to a motor 25, and the output of a displacement gauge 26 is collected by a measuring instrument logger 27. . At that time, by acquiring information on the rotational speeds of the rolling rolls 1, 2 and 3 from the roll rotating device 23, it is possible to associate the displacements obtained by the displacement gauge 26 with the circumferential positions of the rolling rolls 1, 2 and 3. can. In addition, by rotating the rolling rolls 1, 2, and 3 a plurality of times (2 to 5) and taking the autocorrelation of the displacement information obtained by the displacement meter 26, the displacement information for one rotation is specified, and the rolling

roll

1, 2, and 3 circumferential positions and displacement information may be associated with each other.

Then, as shown in FIG. 5, the conformity determination device 30 provided in each of the stands F1 to F5 includes an operation data acquisition unit 31 having a rolling load data acquisition unit 32 and a peripheral speed data acquisition unit 33, a vibration analysis unit 34 , an initial surface shape acquisition unit 35 , a surface shape estimation unit 36 , and a conformity determination unit 37 .
The suitability determination device 30 performs arithmetic processing to realize each function of the operation data acquisition unit 31, the vibration analysis unit 34, the initial surface profile acquisition unit 35, the surface profile estimation unit 36, and the suitability determination unit 37 by executing a program. It is a computer system with functions. By executing various dedicated computer programs pre-stored in hardware, this computer system can realize each function described above on software.

The operation data acquisition unit 31 includes a rolling load data acquisition unit 32 and a peripheral speed data acquisition unit 33. The rolling load data acquisition unit 32 acquires information on the stands F1 to Fn having the rolls to be evaluated selected by the operator from the host computer 14, and based on the information, operates the rolling load of the stands F1 to F5 having the rolls to be evaluated. Perform data acquisition processing. The peripheral speed data acquisition unit 33 acquires information on the stands F1 to Fn where the evaluation target roll is selected by the operator from the host computer 14, and based on the information, acquires the operation data of the peripheral speed of the evaluation target roll. . Information on the stands F1 to Fn on which the rolls to be evaluated are selected by the operator is input to the control computer 13 and sent to the operation data acquisition unit 31 via the host computer 14 .

The rolling load data acquisition unit 32 acquires the rolling load operation data of the stands F1 to F5 having the rolls to be evaluated from the controller 12 based on the above information. The operation data of the rolling load of the stands F1 to F5 is the operation data of the rolling load detected by the rolling load detector 6 during rolling of the steel sheet as the metal strip S. This rolling load operation data is sent to the control controller 12 , and the rolling load data acquisition unit 32 acquires the operation data from the control controller 12 . However, as the rolling load operation data of the stands F1 to F5, the rolling load setting values set by the control computer 13 may be used as the rolling load operation data. As shown in FIG. 13, which will be described later, this is the bonding between the front end of the metal strip S (A, B, C) and the tail end of the preceding metal strip preceding the metal strip S (A, B, C). This is because the rolling load for rolling the metal strip A, the metal strip B, and the metal strip C is set by the control computer 13 at the timings t1, t2, and t3 when the part passes the rolling mill a. Then, the setting value of the rolling load is sent from the control computer 13 to the control controller 12 , and the rolling load data acquisition unit 32 acquires the setting value of the rolling load from the control controller 12 . The operation data of the rolling load may be sent to the vibration analysis unit 34 as time-series data during the rolling of the metal strip S at any time, but the vibration analysis unit 34 is sent to the vibration analysis unit 34 only once when rolling of the metal strip S is started. You can send it to

In addition, the peripheral speed data acquisition unit 33 acquires operation data of the peripheral speed of the evaluation target roll from the controller 12 based on the above information. The operation data of the peripheral speed of the evaluation target roll acquired by the peripheral speed data acquisition unit 33 is obtained from the measured values of the rotation speed of the upper and lower work rolls 1 detected by the rotation speed detector of the roll speed controller 11, It is obtained by conversion using the ratio of the roll diameters of the work roll 1 and the roll to be evaluated. Specifically, using the diameter Dd of the work roll 1 and the rotation speed ωd of the work roll 1 with respect to the diameter De of the roll to be evaluated, the rotation speed ωe of the roll to be evaluated is obtained by ωe = ωd Dd/De can ask. The operation data on the peripheral speed of the evaluation target roll is time-series data, and the peripheral speed of the evaluation target roll during rolling of the steel sheet as the metal strip S is acquired at any time. It is preferable that the peripheral speed of the roll to be evaluated is time-series data with a sampling period arbitrarily set in the range of 0.1 to 5 ms. However, if a speedometer for measuring the rotation speed of the evaluation target roll is installed in each of the stands F1 to F5, the operation data of the peripheral speed of the evaluation target roll acquired by the peripheral speed data acquisition unit 33 is value can be used. The operation data about the peripheral speed of the roll to be evaluated is sent to the surface shape estimator 36 at any time while the metal strip S is being rolled.

In addition, the operation data acquisition unit 31 may acquire other operation data when the metal strip S is rolled, in addition to the operation data of the rolling load and the operation data of the peripheral speed of the roll to be evaluated. For example, the surface hardness, Young's modulus, Poisson's ratio, and the like of the rolling rolls 1, 2, and 3 may be obtained as operational data relating to the attributes of the rolling rolls 1, 2, and 3. As operation data related to rolling conditions, set values and actual values such as the thickness of the material to be rolled, deformation resistance, reduction rate, advance rate, and coefficient of friction may be acquired. The attribute information of the rolling rolls 1, 2, and 3 affects the susceptibility to wear when the rolling rolls to be evaluated contact the other rolling rolls 1, 2, and 3 and wear occurs, thereby determining the surface shape of the rolling rolls to be evaluated. This is because it may affect In addition, the operation data exemplified as the rolling conditions affect the contact pressure, relative sliding speed, and relative sliding amount between the evaluation roll and the other rolling rolls 1, 2, and 3 in contact with each other. This is because it may affect the surface shape of the These operational data are sent to the vibration analysis section 34 or the surface shape estimation section 36 .

Further, the vibration analysis unit 34 analyzes the vibration behavior of the stands F1 to F5 using the rolling load operation data of the stands F1 to F5 having the evaluation target rolls acquired by the rolling load data acquisition unit 32 .
Here, the vibration analysis unit 34 considers the influence of the rolling rolls 1, 2, and 3 other than the rolls to be evaluated on the vibration behavior of the rolls to be evaluated regarding the vibration behavior of the stands F1 to F5 in which the rolls to be evaluated are incorporated. Run a vibration analysis. For example, the upper backup rolls 2 of the four-stage stands F1 to F4 are selected as rolls to be evaluated. In this case, the vibration analysis unit 34 analyzes the vibration behavior including the lower backup roll 2, the upper work roll 1, and the lower work roll 1 that constitute the stands F1 to F4, and evaluates Vibration behavior of the upper backup roll 2, which is a roll, is obtained.

　In the analysis of the vibration behavior of the stands F1 to F5 having the rolls to be evaluated by the vibration analysis unit 34, a rolling mill vibration model that approximates the stands F1 to F5 having the rolls to be evaluated with a mass-spring system is used. Then, the spring constant in this rolling mill vibration model is updated according to the operation data of the rolling load of the stands F1 to F5 having the rolls to be evaluated, and a virtual external force is applied to the rolling mill vibration model with the updated spring constant. Calculate the frequency response when

A rolling mill vibration model approximating the stands F1 to F4 with a mass-spring system in the case where the stands having rolls to be evaluated are four-high stands F1 to F4 will be described below.
As shown in FIG. 7, the rolling mill vibration model that approximates the four-stage stands F1 to F4 with a mass-spring system has upper and lower work rolls 1 and upper and lower backup rolls 2 as mass points, respectively. It is a vibrating model, and damping elements can be added if desired.

In the rolling mill vibration model, m1 is the mass of the upper backup roll 2, m4 is the mass of the lower backup roll 2, m2 is the mass of the upper work roll 1, and m3 is the mass of the lower work roll 1. The spring constant k1 of the spring 41 between the housing and the upper backup roll 2 and the spring constant k5 of the spring 45 between the housing and the lower backup roll 2 depend on the stiffness of the housing and the upper and lower backup rolls 2 shows the spring constant due to bearing deformation and roll deflection. Also, the spring constant k2 of the spring 42 between the upper backup roll 2 and the upper work roll 1 corresponds to the rigidity due to elastic contact deformation between the upper backup roll 2 and the upper work roll 1 . A spring constant k4 of the spring 44 between the lower backup roll 2 and the lower work roll 1 corresponds to the rigidity due to contact elastic deformation between the lower backup roll 2 and the lower work roll 1 . On the other hand, the spring constant k3 of the spring 43 between the upper and lower work rolls 1 is a spring constant calculated from the deformation characteristics of the metal strip S when the metal strip S is rolled by the upper and lower work rolls 1. is. Furthermore, damping elements 46 may be provided as necessary, such as when a hydraulic pressure reduction device is used as a device for raising and lowering the backup rolls 2 by the roll gap controllers 10 of the respective stands F1 to F4.

Here, the spring constant k3 of the spring 43 between the upper and lower work rolls 1 is calculated from the ratio of the variation of the rolling load to the variation of the gap (roll gap) between the upper and lower work rolls 1. be able to. The rolling load may be calculated by using two-dimensional rolling theory, which is an elementary analysis method, and considering the flattening deformation of the upper and lower work rolls 1 (for example, Hitchcock's roll flattening formula). As the two-dimensional rolling theory, methods that are widely used for calculating the rolling load, such as Orowan theory, Karman theory, Bland & Ford's formula, and Hill's approximation formula, can be applied. The mill rigidity K of each of the stands F1 to F4 is obtained from the ratio of the load change of the rolling load detected by the rolling load detector 6 with respect to the change of the roll gap when the upper and lower work rolls 1 are brought into contact when the mill is idling. It is possible to obtain the mill stretch curve (elastic characteristic curve). For the spring constant k3, the diameter of the upper and lower work rolls 1, entry-side plate thickness, entry-side tension, exit-side tension, deformation resistance of the material to be rolled, and the coefficient of friction in the roll bite are known as the standard rolling conditions. When the reference roll gap A is set as the value of , the rolling load A' obtained as a simultaneous solution with the elastic characteristic curves of the stands F1 to F4 is obtained. Next, the rolling load B' when the reference roll gap A is changed to the roll gap B is obtained in the same manner. The ratio of the amount of change from rolling load A' to B' to the amount of change from roll gap A to B obtained in this way can be taken as the spring constant k3.

The spring constant k2 of the spring 42 between the upper backup roll 2 and the upper work roll 1 and the spring constant k4 of the spring 44 between the lower backup roll 2 and the lower work roll 1 are 2 It can be calculated by applying the Hertzian contact theory for the elastic contact deformation of a cylinder. The theory of Hertzian contact is a theoretical solution for contact deformation within the elastic range assuming that no slip or friction occurs between two solid bodies in contact. In this case, the axial approach amount, contact pressure, and contact length can be obtained. A coefficient obtained by linearly approximating the relationship between the axial center approach amount and the contact load at this time may be taken as the spring constant.

On the other hand, the mill stiffness K of each stand F1 to F4 is measured with the upper work roll 1 and the lower work roll 1 in contact with each other. The spring constant k3E for the elastic contact deformation during is calculated by applying the Hertzian contact theory. At this time, the mill stiffness K of the rolling mill corresponds to a composite spring composed of unknown spring constants k1, k5 and known spring constants k2, k3E, k4. Therefore, if one of the spring constants k1 and k5 can be calculated, or if the ratio of the two spring constants can be estimated, the spring constant k1, k1, k5 can be calculated. Normally, the diameters of the upper backup roll 2 and the lower backup roll 2 are equal, so considering that the bending rigidity of the upper backup roll 2 and the lower backup roll 2 are also equivalent, the spring constants k1 and k5 can be assumed to be equal to Thereby, each spring constant k1 to k5 can be determined. Note that the method described in Non-Patent Document 1, for example, may be used as the method for determining each spring constant.

Furthermore, the damping coefficient when the damping element 46 is included in the rolling mill vibration model is obtained by performing a hammering test from the top of the housing 4 with the upper work roll 1 and the lower work roll 1 in contact with each other. It can be estimated from the behavior that the vibration of 4 is attenuated. For example, the amplitude attenuation behavior can be approximated by an exponential function with respect to the time axis, and the attenuation coefficient can be obtained from the functional expression. Since the damping coefficient is a unique value for each of the stands F1 to F4, the predetermined damping coefficient may be stored in the vibration analysis unit 34 as a fixed value.

By the way, the spring constants k1 to k5 of the spring elements that make up the mass-spring model are affected by the rolling load when the metal strip S is rolled. That is, the spring constants k1 to k5 calculated by the above method originally have nonlinear characteristics, but are usually calculated as values that can be linearly approximated in the vicinity of the rolling load when rolling the metal strip S. is. Therefore, in the rolling mill vibration model in which the stands F1 to F4 are approximated by the mass-spring model as described above, the vibration characteristics change according to the rolling load when the metal strip S is rolled. Therefore, in the vibration analysis unit 34 of the present embodiment, when the rolling load acquired by the rolling load data acquisition unit 32 changes, the spring constants k1 to k5 of the rolling mill vibration model are updated according to the operation data of the rolling load. . That is, the vibration analysis unit 34 updates the spring constants k1 to k5 of the rolling mill vibration model, which approximates the stands F1 to F4 in which the rolls to be evaluated are installed, by a mass-spring model, to the latest values according to the operation data of the rolling load. Reset. The vibration analysis unit 34 may acquire time-series data of the rolling load from the rolling load data acquisition unit 32 and update the spring constants k1 to k5 of the rolling mill vibration model as needed. However, if the dimensions and deformation resistance of the metal strip S to be rolled do not fluctuate greatly, the changes in the spring constants k1 to k5 in the rolling mill vibration model can be practically ignored. It is sufficient to update the rolling load operation data once. That is, since the control computer 13 performs the setting calculation before rolling the metal strip S, the set value of the rolling load obtained by the setting calculation is obtained, and the spring constants k1 to k5 are updated using the obtained value. can be

Then, the vibration analysis unit 34 calculates a frequency response when a virtual external force is applied to the rolling mill vibration model with updated spring constants k1 to k5.
In other words, the connection between the mass point element corresponding to the evaluation target roll and the other mass point element coupled by the spring element is virtually released with respect to the rolling mill vibration model in which the stands F1 to F4 are approximated by the mass-spring model. Then, the rolling mill vibration models of the respective stands F1 to F4 are divided into two, and the frequency responses of the divided rolling mill vibration models are calculated for each. When the mass point element corresponding to the roll to be evaluated is combined with the other two mass point elements, it is divided into two steps, step 1 and step 2, and the frequency response corresponding to each step is calculated. Step 1 is a step of calculating a frequency response when a virtual external force is applied by virtually releasing the coupling with one mass element. Step 2 is a step of calculating the frequency response when the coupling with the other mass point element is virtually released and a virtual external force is applied.

A detailed description will be given with reference to FIGS. 8 and 9. FIG. 8 shows a rolling mill vibration model in which a four-stage stand is approximated by a mass-spring system. In the case where the upper work roll 1 is selected as the roll to be evaluated, the coupling with the upper backup roll 2 is virtually released. FIG. 4 is a diagram for explaining an example of calculating a frequency response (step 1). FIG. 9 shows a virtual connection with the lower work roll 1 when the upper work roll 1 is selected as the roll to be evaluated in a rolling mill vibration model in which a four-stage stand is approximated by a mass-spring system. It is a figure for demonstrating the example which opens and calculates a frequency response (step 2).

As shown in FIG. 8, the spring 42 (spring constant k2) that couples with the mass point m1 representing the upper backup roll 2 on the upper side of the mass point m2 representing the upper work roll 1 is a coupling portion C1. Step 1 is to calculate the frequency response for each of the two divided mass-spring models when the spring 42 of the connecting portion C1 is released. On the other hand, as shown in FIG. 9, the spring 43 (spring constant k3) that couples with the mass point m3 representing the lower work roll 1 below the mass point m2 representing the upper work roll 1 is a coupling portion C2. Step 2 is to calculate the frequency response for each of the two divided mass-spring models when the spring element of the coupling portion C2 is released.

A method of calculating the frequency response in step 1 will be described. As shown in FIG. 8, when the joint C1 is opened, the mass-spring model is divided into a vibration system M1-1 above the joint C1 and a vibration system M1-2 below the joint C1. be. With respect to the vibration system M1-1, when an upward force (external force) f acts on the mass point m1 representing the upper backup roll 2 above the coupling portion C1 as an input, A frequency response G1(iω) whose output is the displacement of the mass point m1 at . Similarly, for the vibration system M1-2 divided by the coupling portion C1, a downward force (external force) f is input to the mass point m2 representing the upper work roll 1 below the coupling portion C1. A frequency response G2(iω) whose output is the displacement of the mass points m2, m3, and m4 below the coupling portion C1 when acted on is obtained. However, i indicates an imaginary unit and ω indicates an angular frequency. When represented by transfer functions, they are G ₁ (s) and G ₂ (s). Frequency responses G1(iω), G2(iω) and transfer functions G ₁ (s), G ₂ (s) represent the vibration behavior of each of the stands F1 to F4 centering on the joint C1.

On the other hand, the calculation of the frequency response in step 2 will be described with reference to FIG. When the joint C2 is opened, the mass-spring model is divided into a vibration system M2-1 above the joint C2 and a vibration system M2-2 below the joint C2. For the vibration system M2-1, when an upward force (external force) f acts on the mass point m2 representing the upper work roll 1 above the coupling portion C2 as an input, A frequency response G3(iω) is obtained with displacements of the mass points m2 and m1 at . Similarly, for the vibration system M2-2 divided by the coupling portion C2, a downward force (external force) is input to the mass point m3 representing the lower work roll 1 below the coupling portion C2. A frequency response G4(iω) is obtained by outputting displacements of the mass points m3 and m4 located below the coupling portion C2 when acted on. When represented by transfer functions, they are G ₃ (s) and G ₄ (s). The frequency responses G3(iω), G4(iω) and the transfer functions _G3 (s), _G4 (s) represent the vibration behavior of the rolling mill around the joint C2.

Specifically, the transfer functions G ₁ (s), G ₂ (s), G ₃ (s), and G ₄ (s) corresponding to the examples of FIGS. can be expressed as

If the mass point element corresponding to the roll to be evaluated is coupled to one mass point element but not to the other mass point element, the frequency response of the coupled vibration system is Just ask. For example, when the upper backup roll 2 is selected as the evaluation target roll in FIG. In this case, the spring 41 (spring constant k1) becomes the coupling portion C1, and there is no vibration system including the mass element above the coupling portion C1. Therefore, the transfer function of the vibration system M1-1 is G ₁ (s)=0
And it is sufficient. In addition, although the vibration system M1-2 including the mass element exists below the coupling portion C1, there is no other roll in contact with the upper backup roll 2 at the coupling portion C1.
_G2 (s)=0
becomes. This is because there is no element that contacts the upper backup roll at the upper side (joint portion C1) and vibrates the upper backup roll. Therefore, if the mass point element corresponding to the roll to be evaluated is combined with the mass point element on the lower side but is not combined with the mass point element on the upper side, The transfer functions G ₃ (s) and G ₄ (s) of the vibration system M2-1 and the vibration system 2-2 can be obtained.

Next, a description will be given of a rolling mill vibration model that approximates the stand F5 with a mass-spring system when the stand with the rolls to be evaluated is the six-high stand F5.
As shown in FIG. 10, the rolling mill vibration model approximating the six-high stand F5 with a mass-spring system includes upper and lower work rolls 1, upper and lower backup rolls 2, and upper and lower This is a vibration model with the intermediate rolls 3 as mass points, and damper elements can be added as necessary.

In the rolling mill vibration model, m1 is the mass of the upper backup roll 2, m6 is the mass of the lower backup roll 2, m2 is the mass of the upper intermediate roll 3, m5 is the mass of the lower intermediate roll 3, and m3 is The mass of the upper work roll 1, m4 represents the mass of the lower work roll 1. The spring constant k1 of the spring 51 between the housing and the upper backup roll 2 and the spring constant k7 of the spring 57 between the housing and the lower backup roll 2 depend on the stiffness of the housing and the upper and lower backup rolls 2 shows the spring constant due to bearing deformation and roll deflection. Also, the spring constant k2 of the spring 52 between the upper backup roll 2 and the upper intermediate roll 3 corresponds to the rigidity due to elastic contact deformation between the upper backup roll 2 and the upper intermediate roll 3 . Further, the spring constant k6 of the spring 56 between the lower backup roll 2 and the lower intermediate roll 3 corresponds to the rigidity due to elastic contact deformation between the lower backup roll 2 and the lower intermediate roll 3. . Also, the spring constant k3 of the spring 53 between the upper intermediate roll 3 and the upper work roll 1 corresponds to the rigidity due to elastic contact deformation between the upper intermediate roll 3 and the upper work roll 1 . Further, the spring constant k5 of the spring 55 between the lower intermediate roll 3 and the lower work roll 1 corresponds to the rigidity due to elastic contact deformation between the lower intermediate roll 3 and the lower work roll 1. . On the other hand, the spring constant k4 of the spring 54 between the upper and lower work rolls 1 is a spring constant calculated from the deformation characteristics of the metal strip S when the metal strip S is rolled by the upper and lower work rolls 1. is. Further, the damping element 58 may be provided as necessary, such as when a hydraulic screw down device is used as a device for raising and lowering the backup roll 2 by the roll gap controller 10 of the stand F5.

Then, when the rolling load acquired by the rolling load data acquisition section 32 changes, the vibration analysis section 34 updates the spring constants k1 to k7 of the rolling mill vibration model according to the rolling load operation data. The vibration analysis unit 34 may acquire the rolling load time-series data from the rolling load data acquisition unit 32 and update the spring constants k1 to k7 of the rolling mill vibration model as needed. However, if the dimensions and deformation resistance of the metal strip S to be rolled do not fluctuate greatly, changes in the spring constants k1 to k7 in the rolling mill vibration model can be practically ignored. It is sufficient to update the rolling load operation data once. That is, since the control computer 13 performs the setting calculation before rolling the metal strip S, the set value of the rolling load obtained by the setting calculation is obtained, and the spring constants k1 to k7 are updated using the obtained value. can be

Then, the vibration analysis unit 34 applies a virtual external force to the rolling mill vibration model that approximates the six-high stand F5 with the rolls to be evaluated with updated spring constants k1 to k7 using a mass-spring system. Calculate the frequency response of
In other words, with respect to the rolling mill vibration model that approximates the stand F5 by a mass-spring model, the coupling between the mass element corresponding to the roll to be evaluated and the other mass element coupled by the spring element is virtually released, and the stand F5 The rolling mill vibration model is divided into two, and the frequency response of the divided rolling mill vibration model is calculated for each. When the mass point element corresponding to the roll to be evaluated is combined with the other two mass point elements, it is divided into two steps, step 1 and step 2, and the frequency response corresponding to each step is calculated. Step 1 is a step of calculating a frequency response when a virtual external force is applied by virtually releasing the coupling with one mass element. Step 2 is a step of calculating a frequency response when a virtual external force is applied by virtually releasing the coupling with the other mass element.

A detailed description will be given with reference to FIGS. 11 and 12. FIG. 11 shows a rolling mill vibration model in which a six-high stand is approximated by a mass-spring system. FIG. 4 is a diagram for explaining an example of calculating a frequency response (step 1). FIG. 12 shows a rolling mill vibration model in which a six-high stand is approximated by a mass-spring system. FIG. 10 is a diagram for explaining an example of calculating a frequency response (step 2).

As shown in FIG. 11, the spring 52 (spring constant k2) that couples with the mass point m1 representing the upper backup roll 2 above the mass point m2 representing the upper intermediate roll 3 is a coupling portion C3. Step 1 is to calculate the frequency response for each of the two divided mass-spring models when the spring 52 of the connecting portion C3 is released. On the other hand, as shown in FIG. 12, the spring 53 (spring constant k3) that couples with the mass point m3 representing the upper work roll 1 below the mass point m2 representing the upper intermediate roll 3 is a coupling portion C4. Step 2 is to calculate the frequency response for each of the two divided mass-spring models when the spring element of the coupling portion C4 is released.

A method of calculating the frequency response in step 1 will be described. As shown in FIG. 11, when the joint C3 is opened, the mass-spring model is divided into a vibration system M3-1 above the joint C3 and a vibration system M3-2 below the joint C3. be. With respect to the vibration system M3-1, when an upward force (external force) f acts on the mass point m1 representing the upper backup roll 2 above the coupling portion C3 as an input, A frequency response G5(iω) whose output is the displacement of the mass point m1 at . Similarly, for the vibration system M3-2 divided by the coupling portion C3, a downward force (external force) f is input to the mass point m2 representing the upper intermediate roll 3 below the coupling portion C3. A frequency response G6(iω) is obtained in which the displacements of the mass points m2, m3, m4, m5, and m6 below the coupling portion C3 are output. However, i indicates an imaginary unit and ω indicates an angular frequency. When represented by transfer functions, they are G ₅ (s) and G ₆ (s). The frequency responses G5(iω), G5(iω) and the transfer functions _G5 (s), _G6 (s) represent the vibration behavior of the stand F5 about the joint C3.

On the other hand, the calculation of the frequency response in step 2 will be explained using FIG. When the joint C4 is opened, the mass-spring model is divided into a vibration system M4-1 above the joint C4 and a vibration system M4-2 below the joint C4. For the vibration system M4-1, when an upward force (external force) f acts on the mass point m2 representing the upper intermediate roll 3 above the coupling portion C4 as an input, A frequency response G7(iω) is obtained with displacements of the mass points m2 and m1 at . Similarly, for the vibration system M4-2 divided by the coupling portion C4, a downward force (external force) acts as an input on the mass point m3 representing the upper work roll 1 below the coupling portion C4. A frequency response G8(iω) whose output is the displacement of the mass points m3, m4, m5, and m6 below the coupling portion C4 is obtained. When represented by a transfer function, G ₇ (s) and G ₈ (s). The frequency responses G7(iω), G8(iω) and the transfer functions _G7 (s), _G8 (s) represent the vibration behavior of the rolling mill around the joint C4.

Specifically, the transfer functions G ₅ (s), G ₆ (s), G ₇ (s), and G ₈ (s) corresponding to the examples of FIGS. can be expressed as

G ₆ (s) has a denominator of
( _m6s2 ⁺ _c1s + _k7 ⁺ _k6 ) ( _m5s2 ⁺ _k6 + _k5 ) ( _m4s2 ⁺ _k5 + _k4 ) ( _m3s2 + _k4 + _k3 ) ( _m2s2 ⁺ _k3 ) - k ₆ ² (m ₄ s ² + k ₅ + k ₄ ) (m ₃ s ² + k ₄ + k ₃ ) (m ₂ s ² + k ₃ ) - k ₅ ² (m ₆ s ² + c ₁ s + k ₇ + k ₆ ) (m ₃ s ² +k ₄ +k ₃ )(m ₂ s ² +k ₃ )−k ₄ ² (m ₆ s ² +c ₁ s+k ₇ +k ₆ )(m ₅ s ² +k ₆ +k ₅ )(m ₂ s ² +k ₃ ) - k ₃ ² (m ₆ s ² + c ₁ s + k ₇ + k ₆ ) (m ₅ s ² + k ₆ + k ₅ ) (m ₄ s ² + k ₅ + k ₄ ) + k ₅ ² k ₃ ² (m ₆ s ² + c ₁ s + k ₇ + k ₆ ) + k ₃ ² k ₆ ² (m ₄ s ² + k ₅ + k ₄ ) + k ₄ ² k ₆ ² (m ₂ s ² + k ₃ ),
the molecule
-( _m6s2 ⁺ _c1s + _k7 + _k6 )( _m5s2 ⁺ _k6 ⁺ _k5 )( _m4s2 ⁺ _k5 ⁺ _k4 )( _m3s2 + _k4 + _k3 )+ _k62 ( _m4s ² + _k5 + _k4 )( _m3s2 ⁺ _k4 + _k3 ) ⁺ _k52 ( _m6s2 ₊ ^c1s + _k7 + _k6 )( _m3s2 + _k4 + _k3 ⁾ ⁺ _k42 ( _m6s2 ⁺ c ₁ s+k ₇ +k ₆ )(m ₅ s ² +k ₆ +k ₅ )−k ₄ ² k ₆ ² ,
It can be expressed by the following formula (6).

G ₈ (s) has a denominator of
(m ₆ s ² +c ₁ s +k ₇ +k ₆ )(m ₅ s ² +k ₆ +k ₅ )(m ₄ s ² +k ₅ +k ₄ )(m ₃ s ² +k ₄ )−k ₄ ² {(m ₆ s ² +c ₁ s+k ₇ +k ₆ )(m ₅ s ² +k ₆ +k ₅ )−k ₆ ² }−k ₆ ² (m ₄ s ² +k ₅ +k ₄ )(m ₃ s ² +k ₄ )−k ₅ ² (m ₆ s ² +c ₁ s +k ₇ +k ₆ )(m ₃ s ² +k ₄ ),
the molecule
- (m ₆ s ² + c ₁ s + k ₇ + k ₆ ) (m ₅ s ² + k ₆ + k ₅ ) (m ₄ s ² + k ₅ + k ₄ ) + k ₆ ² (m ₄ s ² + k ₅ + k ₄ ) + k ₅ ² ( m ₆ s ² +c ₁ s + k ₇ + k ₆ ),
It can be expressed by the following formula (8).

If the mass point element corresponding to the roll to be evaluated is coupled to one mass point element but not to the other mass point element, the frequency response of the coupled vibration system is Just ask.
Next, the initial surface shape acquisition unit 35 acquires from the host computer 14 the initial surface shape of the roll to be evaluated before the roll to be evaluated is incorporated in the stands F1 to F5 where the roll to be evaluated is located.

The initial surface shape of the roll to be evaluated represents the initial amplitude of the surface of the roll to be evaluated before the roll to be evaluated is incorporated in the stands F1 to F5, and is a parameter specified after grinding the roll to be evaluated by a roll grinder. be. Specifically, the operator can measure the surface shape of the roll to be evaluated after grinding, and obtain the difference between the measured maximum diameter and minimum diameter as the initial amplitude α. In addition, as the surface shape information of the evaluation target roll before the evaluation target roll is incorporated in the stands F1 to F5, the surface profile of the evaluation target roll in the circumferential direction after roll grinding is subjected to Fourier series expansion for each pitch p Initial amplitude μ0 ( p) may be specified. The initial surface shape of the roll to be evaluated is input to the control computer 13 by the operator when the operator inputs information on the selected roll to be evaluated into the control computer 13, and is passed through the host computer 14 to obtain the initial surface shape. It is sent to the shape acquisition unit 35 .

In addition, the surface shape estimating unit 36, in addition to the analysis result of the vibration behavior of the stands F1 to F5 having the evaluation target roll by the vibration analysis unit 34 and the peripheral speed operation data of the evaluation target roll acquired by the peripheral speed data acquiring unit 33 Then, using the initial surface shape of the evaluation target roll acquired by the initial surface shape acquisition unit 35, the surface shape of the evaluation target roll is estimated.
Here, the analysis result of the vibration behavior of the stands F1 to F5 having the roll to be evaluated by the vibration analysis unit 34 is the frequency response calculated as follows, and is sent from the vibration analysis unit 34 to the surface shape estimation unit 36. . That is, when calculating the frequency response, a rolling mill vibration model that approximates the stands F1 to F5 having the rolls to be evaluated by a mass-spring system is used. Then, the spring constants k1 to k7 in this rolling mill vibration model are updated according to the rolling load operation data of the stands F1 to F5 having the rolls to be evaluated. The frequency response is calculated when a virtual external force is applied to the rolling mill vibration model with updated spring constants k1 to k7.

Further, the operation data of the peripheral speed of the evaluation target roll acquired by the peripheral speed data acquiring unit 33 is sent from the peripheral speed data acquiring unit 33 to the surface shape estimating unit 36 .
The evaluation target rolls incorporated in the stands F1 to F5 receive periodic contact loads from other rolling rolls coming into contact with the metal strip S during rolling or from the metal strip S, which is the material to be rolled. The periodic contact load in this case acts on the roll to be evaluated as a load obtained by combining vibrations of multiple frequencies. Such a load on the roll to be evaluated gradually progresses wear between the solids in contact with each other, and as a result, unevenness with a specific period develops, and the surface shape of the roll to be evaluated may become polygonal. be. Specifically, a minute relative slip corresponding to the vibration frequency occurs between the roll to be evaluated and other solids that come into contact with it, and the resulting minute wear grows at a specific pitch. becomes polygonal.

The surface shape estimating unit 36 uses an index that represents the degree of damage that the evaluation target roll receives from other solids that come into contact with the evaluation target roll when vibrations of a plurality of frequencies are applied to the evaluation target roll. The surface shape of the evaluation target roll formed during rolling of S is estimated.
The surface shape estimator 36 estimates the surface shape of the roll to be evaluated using a parameter called "pitch damage degree" described below. The “pitch damage degree” is the frequency response characteristics of each stand F1 to F5 calculated using the rolling mill vibration model in the vibration analysis unit 34 and the peripheral speed of the evaluation target roll acquired by the peripheral speed data acquisition unit 33. It is a parameter for calculating the degree of damage associated with the pitch of the unevenness formed on the surface of the evaluation target roll from the operation data of V (m/sec), and can be defined as follows.

First, when the frequency response is calculated using a rolling mill vibration model that approximates the four-stage stands F1 to F4 with the rolls to be evaluated by a mass-spring system, the degree of pitch damage to the joint C1 calculated in step 1 Δλ1(p) is expressed by the following equation (9) using frequency responses G1(iω) and G2(iω).

However, p is the evaluation pitch (m) of the unevenness formed on the surface shape of the roll to be evaluated. Further, k ₀ (N/m) is the spring constant at the joint C1, ν (m/N) is the wear progress coefficient at the joint C1, and the wear rate (m/N ). Furthermore, T (sec) is the rotation cycle of the roll to be evaluated. Note that ω ₀ (rad/sec) is the angular frequency corresponding to the evaluation pitch p. ).

The degree of pitch damage Δλ1(p) is associated with the amount of wear (degree of damage) of the pitch unevenness formed on the surface of the roll to be evaluated due to the vibration at the coupling portion C1, and naturally follows the amplitude of the pitch unevenness. It corresponds to the amount of change per unit time of the value obtained by applying logarithm.
Similarly, the degree of pitch damage Δλ2(p) for the coupling portion C2 is expressed by the following equation (11) using the frequency responses G3(iω) and G4(iω).

At this time, since the evaluation target roll receives vibration from the upper and lower contact points and the surface unevenness is formed, the pitch damage degree Δλ (p) of the evaluation target roll is
Δλ(p)=Δλ1(p)+Δλ2(p)
can be represented by The degree of pitch damage Δλ(p) of the roll to be evaluated has a characteristic of accumulating with the vibration of the rolling mill, and the cumulative degree of pitch damage λ(p) is defined as the following equation (12).

Here, Δt is the sampling cycle of the peripheral speed of the rolling rolls acquired by the operation data acquiring unit. Depending on the rolling conditions, the degree of pitch damage Δλ(p) may become negative, which means that the unevenness corresponding to the pitch p gradually decreases.
When the cumulative pitch damage degree λ(p) is obtained in this way, the amplitude information u(p) corresponding to the pitch p in the process of rolling the metal strip is calculated by the following equation (13). .

However, α represents the initial surface shape of the evaluation target roll input from the initial surface shape acquisition unit 35, that is, the initial amplitude of the surface of the evaluation target roll before the evaluation target roll is incorporated in the stands F1 to F4, and the evaluation It is a parameter specified after the target roll is ground by a roll grinder. Specifically, the operator can measure the surface shape of the roll to be evaluated after grinding, and obtain the difference between the measured maximum diameter and minimum diameter as the initial amplitude α. In addition, as the surface shape information of the evaluation target roll before the evaluation target roll is incorporated in the stands F1 to F4, the surface profile of the evaluation target roll in the circumferential direction after roll grinding is subjected to Fourier series expansion for each pitch p Initial amplitude μ0 ( p) may be specified.
When the initial amplitude μ0(p) is specified for each pitch p, the amplitude information u(p) corresponding to the pitch p can be calculated by the following equation (14).

Note that when the frequency response is calculated using a rolling mill vibration model that approximates the six-high stand F5 with the rolls to be evaluated by a mass-spring system, the amplitude information u(p) corresponding to the pitch p is the same as described above. It can be calculated by the method of

As another aspect of the surface shape estimating unit 36, the frequency response of each stand F1 to F5, the actual data of the peripheral speed of the roll to be evaluated, and the surface shape of the roll to be evaluated are evaluated based on the past operation results. The surface shape of the roll may be estimated. For example, frequency responses G ₁ (s), G ₂ (s), G ₃ (s), G ₄ (s), G ₅ (s), G ₆ ( s), G ₇ (s), G ₈ (s) performance data, operation performance data such as average speed and maximum speed as peripheral speed of the roll to be evaluated, and evaluation measured after finishing rolling of metal strip S The measurement results of the surface profile of the target roll are stored in a database in association with each other. Then, when the metal strip S is rolled, a roll to be evaluated may be set, the operation data acquisition unit 31 may acquire these data, and the data may be sent to the surface shape estimation unit 36 .

Then, the surface shape of the roll to be evaluated estimated by the surface shape estimating unit 36, that is, the amplitude information u(p) corresponding to the pitch p of the surface of the roll to be evaluated is applied to the conformity determination unit connected to the surface shape estimating unit 36. It is sent to section 37 .
The suitability determination unit 37 performs suitability determination of the evaluation target roll based on the surface shape of the evaluation target roll estimated by the surface shape estimation unit 36 . In other words, the conformity determination unit 37 refers to the value of the amplitude information u(p) corresponding to the surface pitch p of the evaluation target roll calculated by the surface shape estimation unit 36 . Then, if the value of the information u(p) corresponding to the pitch p of the roll to be evaluated is less than the preset upper limit value of the amplitude corresponding to the pitch p, the conformity determination unit 37 determines conformity (acceptance). If it is more than that, it will be determined as non-conforming (failed).

Note that the upper limit value of the amplitude corresponding to the preset pitch p is set in advance when it is known from past operation results and chatter mark occurrence results that irregularities tend to grow at a specific pitch p. This is the upper limit value of the amplitude corresponding to such a pitch p set as the surface shape of the roll to be evaluated. As a result, it is possible to appropriately manage the replacement timing of the rolling rolls, and to prevent a decrease in the production efficiency and work rate of the rolling mill a.
Then, the determination result by the conformity determination section 37 is sent to the display device 38 connected to the conformity determination section 37 . The display device 38 displays the output of the result, that is, the determination result by the conformance determining section 37 .

(Conformity determination method for rolling rolls)
In the method for determining suitability of a rolling roll according to the present embodiment, a rolling roll is arbitrarily selected from a plurality of rolling

rolls

1, 2, and 3 of arbitrary stands F1 to F5 using a rolling roll suitability determination device 30. Perform conformity judgment of the role to be evaluated.
This conformity determination method will be described with reference to FIGS. 6 and 13. FIG. FIG. 6 is a flow chart for explaining the flow of processing in the high-level computer 14 and conformity determining device 30 of the rolling mill a shown in FIG. FIG. 13 is a graph showing changes in the peripheral speed of the rolling rolls 1, 2, and 3 and the timing of judging suitability of the rolls to be evaluated when the metal strip S is continuously rolled using the rolling mill a shown in FIG. .

A normal rolling mill a continuously rolls a plurality of metal strips S, so in the example shown in FIG. 13, metal strips A, B, and C are rolled in this order. The front end of the metal strip A and the tail end of the preceding metal strip preceding the metal strip A are joined by welding. Then, at the timing t1 when the joint passes through the rolling mill a, processing is performed in the high-level computer 14 and conformity determining device 30 of the rolling mill a shown in FIG.

Prior to the processing of the host computer 14 and the suitability determination device 30 in FIG. 13 and the information is input to the host computer 14 . The information about the selected roll to be evaluated is information about which of the

rolls

1, 2, and 3 in which of the stands F1 to F5 was selected as the roll to be evaluated.
Then, the host computer 14 selects an evaluation target role based on the information input to the host computer 14 in step S1. Then, the host computer 14 sends the information of the selected roll to be evaluated to the operation data acquisition section 31 of the suitability determination device 30 provided at the stand F1 to F5 where the roll to be evaluated is located. In addition, the host computer 14 sends information on the initial surface shape of the roll to be evaluated to the initial surface shape acquisition unit 35 of the suitability determination device 30 provided in the stand F1 to F5 where the roll to be evaluated is located (selection step of roll to be evaluated ).

Next, in step S2, the initial surface shape acquisition unit 35 of the suitability determination device 30 provided in the stand F1 to F5 where the roll to be evaluated is provided acquires information on the initial surface shape of the roll to be evaluated, that is, the surface of the roll to be evaluated. The initial amplitude α is acquired from the host computer 14 (initial surface profile acquisition step).
In addition, the initial surface profile acquisition unit 35 specified the initial amplitude μ0(p) for each pitch p by Fourier series expansion of the circumferential surface profile of the evaluation target roll after roll grinding as the surface profile information of the evaluation target roll. You can get things.

Next, in step S3, the rolling load data acquisition unit 32 of the suitability determination device 30 provided in the stand F1 to F5 having the roll to be evaluated selects the roll to be evaluated based on the selection information of the roll to be evaluated from the host computer 14. Operation data of the rolling load of a certain stand F1 to F5 is obtained from the controller 12 (rolling load data obtaining step).
Here, the operation data of the rolling load of the stands F1 to F5 is the operation of the rolling load detected by the rolling load detector 6 when the joint between the metal strip A and the preceding metal strip passes through the stands F1 to F5. Data. However, as the rolling load operation data of the stands F1 to F5, the rolling load setting values set by the control computer 13 may be used as the rolling load operation data. When the metal strip A is rolled by the control computer 13 at timing t1 when the joint between the leading end of the metal strip A and the trailing end of the preceding metal strip preceding the metal strip A passes through the rolling mill a This is because the rolling load of is set.

Next, in step S4, the peripheral speed data acquisition unit 33 of the suitability determination device 30 provided in the stand F1 to F5 where the roll to be evaluated is located, selects the roll to be evaluated based on the selection information of the roll to be evaluated from the host computer 14. Operation data of peripheral speed is acquired from the controller 12 (peripheral speed data acquisition step).
Here, the operation data of the peripheral speed of the evaluation target roll acquired by the peripheral speed data acquisition unit 33 is the actual measurement of the rotational speed of the upper and lower work rolls 1 detected by the rotational speed detector of the roll speed controller 11. It is obtained by converting the value using the ratio of the roll diameters of the work roll 1 and the roll to be evaluated.

Next, in step S5, the vibration analysis unit 34 of the suitability determination device 30 provided in the stands F1 to F5 having the rolls to be evaluated acquires the stand F1 to F5 having the rolls to be evaluated acquired in step S3 (rolling load acquisition step). The vibration behavior of the stands F1 to F5 is analyzed using the rolling load operation data (vibration analysis step).
In the analysis of the vibration behavior of the stands F1 to F5 with the rolls to be evaluated by the vibration analysis unit 34, as described above, the rolling mill vibration model that approximates the stands F1 to F5 with the rolls to be evaluated by a mass-spring system is used. . Then, the spring constants k1 to k5 in this rolling mill vibration model are updated according to the rolling load operation data of the stands F1 to F5 having the rolls to be evaluated acquired in step S3. Then, the frequency response when a virtual external force is applied to the rolling mill vibration model with updated spring constants k1 to k5 is calculated.

Here, the transfer function G ₁ (s ), G ₂ (s), G ₃ (s), and G ₄ (s) can be expressed by the formulas (1) to (4) described above.
Also transfer functions _G5 (s), G ₆ (s), G ₇ (s), and G ₈ (s) can be expressed by the aforementioned formulas (5) to (8).

Next, in step S6, the surface shape estimating section 36 estimates the surface shape of the evaluation target roll during rolling of the metal strip S (surface shape estimating step). When estimating the surface shape of the roll to be evaluated, the analysis result of the vibration behavior of the stands F1 to F5 having the roll to be evaluated in step S5 (vibration analysis step) is used. Further, when estimating the surface shape of the evaluation target roll, the operation data of the peripheral speed of the evaluation target roll acquired in step S4 (peripheral speed data acquisition step) is used. Furthermore, when estimating the surface shape of the roll to be evaluated, the initial surface shape of the roll to be evaluated acquired in step S2 (initial surface shape acquisition step) is used.

Here, the analysis result of the vibration behavior of the stands F1 to F5 having the rolls to be evaluated in step S5 (vibration analysis step) is the frequency response calculated as follows, and sent to That is, when calculating the frequency response, a rolling mill vibration model that approximates the stands F1 to F5 having the rolls to be evaluated by a mass-spring system is used. Then, the spring constants k1 to k7 in this rolling mill vibration model are updated according to the rolling load operation data of the stands F1 to F5 having the rolls to be evaluated. The frequency response is calculated when a virtual external force is applied to the rolling mill vibration model with updated spring constants k1 to k7.
In addition, the operation data of the peripheral speed of the evaluation target roll acquired in step S<b>4 (peripheral speed data acquisition step) is sent from the peripheral speed data acquisition section 33 to the surface shape estimation section 36 .

The evaluation target rolls incorporated in the stands F1 to F5 receive periodic contact loads from other rolling rolls that come into contact during rolling of the metal strip S or from the metal strip S that is the material to be rolled. The periodic contact load in this case acts on the roll to be evaluated as a load obtained by combining vibrations of multiple frequencies. Such a load on the roll to be evaluated gradually progresses wear between the solids in contact with each other, and as a result, unevenness with a specific period develops, and the surface shape of the roll to be evaluated may become polygonal. be. Specifically, a minute relative slip corresponding to the vibration frequency occurs between the roll to be evaluated and other solids that come into contact with it, and the resulting minute wear grows at a specific pitch. becomes polygonal.

In step S6, the surface shape estimating unit 36 uses an index representing the degree of damage that the evaluation target roll receives from other solids that come into contact with the evaluation target roll when vibrations of a plurality of frequencies are applied to the evaluation target roll. , the surface shape of the roll to be evaluated formed during the rolling of the metal strip S is estimated.
In step S6, the surface shape estimating section 36 estimates the surface shape of the evaluation target roll using the parameter called the "pitch damage degree" described above. The “pitch damage degree” refers to the frequency response characteristics of each stand F1 to F5 calculated using the rolling mill vibration model in step S5 (vibration analysis step) and the frequency response characteristics obtained in step S4 (peripheral velocity data acquisition step). It is a parameter for calculating the degree of damage associated with the pitch of the unevenness formed on the surface of the roll to be evaluated from the operational data of the peripheral speed of the roll to be evaluated.

First, when the frequency response is calculated using a rolling mill vibration model that approximates the four-stage stands F1 to F4 with the rolls to be evaluated by a mass-spring system, the degree of pitch damage to the joint C1 calculated in step 1 Δλ1(p) is expressed by the above equation (9) using the frequency responses G1(iω) and G2(iω).
Also, the degree of pitch-related damage Δλ2(p) for the coupling portion C2 is expressed by the above-described equation (11) using the frequency responses G3(iω) and G4(iω).
At this time, since the evaluation target roll receives vibration from the upper and lower contact points and the surface unevenness is formed, the pitch damage degree Δλ (p) of the evaluation target roll is
Δλ(p)=Δλ1(p)+Δλ2(p)
can be represented by The degree of pitch damage Δλ(p) of the roll to be evaluated has the characteristic of accumulating along with the vibration of the rolling mill, and the cumulative degree of pitch damage λ(p) is defined as in the above-described formula (12).

When the cumulative pitch damage degree λ(p) is obtained in this way, the amplitude information u(p) corresponding to the pitch p in the process of rolling the metal strip is calculated by the above equation (13). .
Here, α is the initial surface shape of the evaluation target roll acquired in step S2 (initial surface shape acquisition step), that is, the initial amplitude of the surface of the evaluation target roll before the evaluation target roll is incorporated in the stands F1 to F4. It is a parameter specified after grinding the roll to be evaluated by the roll grinder. Specifically, the operator can measure the surface shape of the roll to be evaluated after grinding, and obtain the difference between the measured maximum diameter and minimum diameter as the initial amplitude α. In addition, as the surface shape information of the evaluation target roll before the evaluation target roll is incorporated in the stands F1 to F4, the surface profile of the evaluation target roll in the circumferential direction after roll grinding is subjected to Fourier series expansion for each pitch p Initial amplitude μ0 ( p) may be specified.

When the initial amplitude μ0(p) is specified for each pitch p, the amplitude information u(p) corresponding to the pitch p can be calculated by the above equation (14).
Note that when the frequency response is calculated using a rolling mill vibration model that approximates the six-high stand F5 with the rolls to be evaluated by a mass-spring system, the amplitude information u(p) corresponding to the pitch p is the same as described above. It can be calculated by the method of
Then, the surface shape of the roll to be evaluated estimated by the surface shape estimating unit 36, that is, the amplitude information u(p) corresponding to the pitch p of the surface of the roll to be evaluated is applied to the conformity determination unit connected to the surface shape estimating unit 36. It is sent to section 37 .

Then, in step S7, the suitability determination unit 37 performs suitability determination of the evaluation target roll based on the surface shape of the evaluation target roll estimated by the surface shape estimation unit 36 (suitability determination step). Specifically, the conformity determination unit 37 refers to the value of the amplitude information u(p) corresponding to the surface pitch p of the evaluation target roll calculated by the surface shape estimation unit 36 . Then, if the value of the information u(p) corresponding to the pitch p of the roll to be evaluated is less than the preset upper limit value of the amplitude corresponding to the pitch p, the conformity determination unit 37 determines conformity (acceptance). If it is more than that, it will be determined as non-conforming (failed).

Note that the upper limit value of the amplitude corresponding to the preset pitch p is set in advance when it is known from past operation results and chatter mark occurrence results that irregularities tend to grow at a specific pitch p. This is the upper limit value of the amplitude corresponding to such a pitch p set as the surface shape of the roll to be evaluated. As a result, it is possible to appropriately manage the replacement timing of the rolling rolls, and to prevent a decrease in the production efficiency and work rate of the rolling mill a.
Then, in step S8, the display device 38 displays the output of the result, that is, the determination result of step S7 (display step). An operator who performs a rolling operation can confirm the suitability determination result of the roll to be evaluated on the display device 38 .
As a result, the processing in the host computer 14 and the suitability determination device 30 at the timing t1 when the joint between the front end of the metal strip A and the tail end of the preceding metal strip preceding the metal strip A passes through the rolling mill a. ends.

Then, in FIG. 13, at timing t2 when the joint between the front end of the metal strip B and the tail end of the metal strip A preceding the metal strip B passes through the rolling mill a, the host computer shown in FIG. 14 and the processing in the match determining device 30 are repeated. Also, at timing t3 when the joint between the front end of the metal strip C and the tail end of the metal strip B preceding the metal strip C passes through the rolling mill a, the high-level computer 14 shown in FIG. The processing in the determination device 30 is repeated.

As described above, according to the method for determining suitability of rolling rolls according to the present embodiment, any stand F1 to A suitability determination is made for a roll to be evaluated, which is a rolling roll arbitrarily selected from a plurality of rolling

rolls

1, 2, and 3 in F5. The suitability determination method includes a rolling load data acquisition step (step S3) for acquiring rolling load operation data of the stands F1 to F5 having rolls to be evaluated. The suitability determination method also includes a peripheral speed data acquisition step (step S4) of acquiring operation data of the peripheral speed of the roll to be evaluated. In addition, the conformity determination method uses the rolling load operation data of the stands F1 to F5 having the rolls to be evaluated acquired in the rolling load data acquisition step (step S3) to analyze the vibration behavior of the stands F1 to F5. An analysis step (step S5) is included. In addition, the conformity determination method includes the analysis result of the vibration behavior of the stands F1 to F5 having the evaluation target roll in the vibration analysis step (step S5) and the peripheral speed of the evaluation target roll acquired in the peripheral speed data acquisition step (step S4). and a surface shape estimating step (step S6) of estimating the surface shape of the evaluation target roll during rolling of the metal strip S from the operation data. The suitability determination method also includes a suitability determination step (step S7) for determining suitability of the evaluation target roll based on the surface shape of the evaluation target roll estimated in the surface shape estimation step (step S6).

As a result, by estimating the surface shape of the roll to be evaluated online, the state of polygonal wear of the roll to be evaluated that occurs during rolling can be estimated online, and based on the estimated polygonal wear state of the roll roll can be determined to prevent mild chatter marks caused by polygonal wear.

Further, according to the method for determining suitability of a rolling roll according to the present embodiment, the initial surface shape acquisition step of acquiring the initial surface shape of the roll to be evaluated before the roll to be evaluated is incorporated in the stands F1 to F5 having the roll to be evaluated. (Step S2). Then, in the surface shape estimation step (step S6), the analysis result of the vibration behavior of the stand having the evaluation target roll in the vibration analysis step (step S5) and the circumference of the evaluation target roll acquired in the peripheral speed data acquisition step (step S4) In addition to the speed operation data, the initial surface profile of the evaluation target roll acquired in the initial surface profile acquisition step (step S2) is used to estimate the surface profile of the evaluation target roll during rolling of the metal strip S.

This makes it possible to more accurately estimate the surface shape of the roll to be evaluated.
Further, according to the method for determining suitability of a rolling roll according to the present embodiment, the surface shape of the roll to be evaluated is determined by the amplitude information u(p) associated with the pitch p of the unevenness formed on the surface of the roll to be evaluated. be.
As a result, the amplitude information u(p) associated with the pitch p of the unevenness formed on the surface of the evaluation target roll, which accurately represents the state of polygonal wear of the evaluation target roll during rolling, is estimated. , it is possible to adequately prevent mild chatter marks caused by polygon wear.

Further, according to the method for determining suitability of the rolling rolls according to the present embodiment, the analysis of the vibration behavior of the stands F1 to F5 having the rolls to be evaluated in the vibration analysis step (step S5) is performed using the stands F1 to F5 having the rolls to be evaluated. is approximated by a mass-spring system. Then, the spring constants k1 to k7 in the rolling mill vibration model are updated according to the rolling load operation data of the stands F1 to F5 having rolls to be evaluated. Then, the frequency response when a virtual external force is applied to the rolling mill vibration model with updated spring constants k1 to k7 is calculated.
As a result, it is possible to calculate the frequency response of the rolling mill vibration model that approximates each of the stands F1 to F4 by a mass-spring model, corresponding to changes in the vibration characteristics according to the rolling load. A more appropriate analysis result of the vibration behavior of the stands F1 to F5 can be obtained.

(Method of rolling metal strip)
Further, in the metal strip rolling method according to the present embodiment, the suitability determination of the roll to be evaluated is performed during rolling of the metal strip S using the above-described method for determining suitability of the rolling rolls, and when the result of the suitability determination is unsuitable Secondly, the rolls to be evaluated are replaced with new rolling rolls, and the metal strip S is rolled.
That is, when the roll to be evaluated is determined to be unsuitable by the above-described method for determining suitability of rolling rolls, the rolling mill a is temporarily stopped. Then, at least the non-conforming rolls to be evaluated are extracted from the corresponding stands F1 to F5, and after they are replaced with new rolling rolls that have been ground by the roll grinder, the rolling of the metal strip S may be restarted. As a result, generation of chatter marks on the surface of the metal band S can be prevented, and the metal band S can be manufactured with a high yield.

(Manufacturing method of cold-rolled steel sheet)
Then, it is preferable to manufacture a cold-rolled steel sheet using the above-described metal strip rolling method. In other words, it is preferable to use a cold-rolled steel sheet as the metal strip S described above. This is because a cold-rolled steel sheet is required to have a uniform surface appearance, and even a slight chatter mark is determined to be a surface defect.

Although the embodiment of the present invention has been described above, the present invention is not limited to this and various modifications and improvements can be made.
For example, in the present embodiment, the rolling mill a has five stands, the stands F1 to F4 are four-high rolling mills, and the stand F5 is a six-high rolling mill, but the number of stands is limited to five. not. Further, it is possible to appropriately determine which stand among the plurality of stands is to be a 4-high rolling mill or a 6-high rolling mill.

Also, the suitability determination device 30 does not necessarily need to include the initial surface shape acquisition unit 35 that acquires the initial surface shape of the evaluation target roll before the evaluation target roll is assembled in the stands F1 to F5 where the evaluation target roll is located. Then, the surface shape estimating unit 36 adds the analysis results of the vibration behavior of the stands F1 to F5 having the evaluation target roll by the vibration analysis unit 34 and the operation data of the peripheral speed of the evaluation target roll acquired by the peripheral speed data acquisition unit 33 Therefore, it is not always necessary to estimate the surface shape of the roll to be evaluated using the initial surface shape of the roll to be evaluated acquired by the initial surface shape acquiring unit 35 .

Further, the surface shape of the roll to be evaluated estimated by the surface shape estimating unit 36 does not necessarily have to be the amplitude information u(p) associated with the pitch p of the unevenness formed on the surface of the roll to be evaluated.
In addition, the vibration analysis of the vibration behavior of the stands F1 to F5 with the rolls to be evaluated by the vibration analysis unit 34 uses a rolling mill vibration model that approximates the stands F1 to F5 with the rolls to be evaluated by a mass-spring system. The spring constants k1 to k7 in the model are updated according to the operation data of the rolling load of the stands F1 to F5 having the rolls to be evaluated, and a virtual external force is applied to the rolling mill vibration model with the updated spring constants k1 to k7. It is not always necessary to calculate the frequency response when given.

As an example of the present invention, an example targeting a rolling mill (tandem rolling mill) a with four stands F1 to F4 in which the front three stands F1 to F3 are a four-high rolling mill and the final stand F4 is a six-high rolling mill explain.
In this example, the backup roll 2 above the third stand F3, which is a four-high rolling mill, was selected as the roll to be evaluated. The diameter of the roll to be evaluated is 1370 mm. The work rolls 1 on the upper and lower sides of the stand F3 had a diameter ranging from 480 to 550 mm, and a plurality of metal strips S were rolled while exchanging the work rolls 1 at any time. The rolls to be evaluated were forged steel rolls, which were finished with a roll grinder to have a center line average roughness of 0.8 μmRa and then loaded into the stand F3. As a result of measuring the unevenness in the circumferential direction of the roll to be evaluated after the roll grinding, the maximum amplitude was 0.1 μm, so the initial amplitude α of the surface of the roll to be evaluated was set to 0.1 μm.

The metal strip S rolled by the rolling mill a is a cold-rolled sheet steel including ultra-low carbon steel, high-strength steel, and the like. The rolling speed (peripheral speed of the upper and lower work rolls 1 of the final stand F4) has a minimum speed of 200 m/min and a maximum speed of 1300 m/min. Rolling was performed at the maximum speed set by the control computer 13 according to the plate width, base material length) and steel type. However, depending on the state of supply of the metal strip S to the rolling mill a, etc., the rolling speed was appropriately reset during the rolling of the metal strip at the discretion of the operator.
In this embodiment, the operator provides information on the selected evaluation target roll (information that the backup roll 2 on the upper side of the third stand F3 is the evaluation target roll) and the initial surface shape of the evaluation target roll (surface of the evaluation target roll is 0.1 μm) is input to the control computer 13 , and the information is input to the host computer 14 .

Then, in step S1, the host computer 14 selects a roll to be evaluated based on the information input to the host computer 14, and transmits the information of the selected roll to be evaluated to the conformity judgment provided at the stand F3 where the roll to be evaluated is located. It was sent to the operation data acquisition unit 31 of the device 30 . In addition, the host computer 14 sent the information on the initial surface shape of the roll to be evaluated to the initial surface shape acquiring section 35 of the suitability determination device 30 provided at the stand F3 where the roll to be evaluated is located.
Next, in step S2, the initial surface shape acquisition unit 35 of the suitability determination device 30 provided on the stand F3 where the roll to be evaluated is located acquires information on the initial surface shape of the roll to be evaluated, that is, the initial amplitude of the surface of the roll to be evaluated α (=0.1 μm) was acquired from the host computer 14 .

Next, in step S3, the rolling load data acquisition unit 32 of the suitability determination device 30 provided in the stand F3 having the roll to be evaluated, based on the selection information of the roll to be evaluated from the host computer 14, the stand having the roll to be evaluated The operation data of the rolling load of F3 was acquired from the controller 12 for control.
Here, the operation data of the rolling load of the stand F3 is obtained by continuously rolling the trailing metal strip having the joint portion of the leading metal strip and the trailing metal strip with respect to the stand F3. From the result of the setting calculation by the control computer 13 executed before the leading end of the rolling mill passes the rolling mill a, the setting value of the rolling load was 5000 kN to 25000 kN.

Next, in step S4, the circumferential speed data acquisition unit 33 of the suitability determination device 30 provided in the stand F3 where the roll to be evaluated is located, based on the selection information of the roll to be evaluated from the host computer 14, the circumferential speed of the roll to be evaluated was acquired from the controller 12 for control.
Here, the operation data of the peripheral speed of the evaluation target roll acquired by the peripheral speed data acquisition unit 33 is the actual measurement of the rotational speed of the upper and lower work rolls 1 detected by the rotational speed detector of the roll speed controller 11. From the value, it was obtained by converting using the ratio of the roll diameters of the work roll 1 and the roll to be evaluated.

Next, in step S5, the vibration analysis unit 34 of the conformity determination device 30 provided in the stand F3 having the roll to be evaluated uses the rolling load operation data of the stand F3 having the roll to be evaluated acquired in step S3. The vibration behavior of stand F3 was analyzed.
In the analysis of the vibration behavior of the stand F3 having the roll to be evaluated by the vibration analysis unit 34, a rolling mill vibration model that approximates the stand F3 having the roll to be evaluated with a mass-spring system is used. Then, the spring constants k1 to k5 in this rolling mill vibration model were updated according to the rolling load operation data of the stand F3 having the evaluation target roll acquired in step S3. Then, a frequency response was calculated when a virtual external force was applied to the rolling mill vibration model with updated spring constants k1 to k5.

Here, the vibration analysis unit 34 virtually releases the connection between the mass point m1 representing the backup roll 2 on the upper side of the third stand F3 having the roll to be evaluated and the other mass points coupled by the

springs

41 and 42, The mass-spring model of stand F3 was divided into two, and the frequency response of the divided mass-spring model was calculated for each. Other mass points connected by the spring 41 to the mass point m1 representing the upper backup roll 2 do not exist because there is no rolling roll above the mass point m1. As for the mass point m1 representing the upper backup roll 2 and the other mass point connected by the spring 42, the mass point m2 represents the upper work roll 1 because the upper work roll 1 exists below the mass point m1.

Transfer function G ₁ (s) representing frequency responses G1(iω), G2(iω), G3(iω), G4(iω) since there is no rolling roll contacting the upper backup roll 2 from above , G ₂ (s), G ₃ (s), and G ₄ (s) are respectively composed of the following equations (15) to (18).
_G1 (s)=0 (15)
_G2 (s)=0 (16)

Next, the surface shape estimator 36 of the suitability determination device 30 provided in the stand F3 where the roll to be evaluated is located estimates the surface shape of the roll to be evaluated during rolling of the metal strip S in step S6. When estimating the surface shape of the evaluation target roll, the analysis result (frequency response) of the vibration behavior of the stand F3 having the evaluation target roll in step S5 and the operation data of the peripheral speed of the evaluation target roll acquired in step S4 were used. In estimating the surface shape of the roll to be evaluated, the initial surface shape of the roll to be evaluated obtained in step S2 was also used.

That is, the surface shape estimating unit 36 calculated the degree of pitch damage Δλ1(p) using the above equation (9), and calculated the degree of pitch damage Δλ2(p) using the above equation (11). Further, the pitch damage degree Δλ(p) of the roll to be evaluated is calculated by λ(p)=Δλ1(p)+Δλ2(p), and the cumulative pitch damage degree λ(p) of the roll to be evaluated is calculated as (12) Calculated by Further, the amplitude information u(p) corresponding to the pitch p was calculated by the equation (13) using the initial amplitude α. The wear progress coefficient ν when calculating the pitch damage degrees Δλ1(p) and Δλ2(p) was set to 1.0×10 ⁻¹⁴ m/N.

In this example, as the surface shape of the roll to be evaluated, attention was focused on the amplitude at a pitch p of 25 mm, because the pitch of the chatter marks generated on the metal band S in the past was 25 mm. Then, the conformity determining unit 37 refers to the value of the amplitude information u(p) corresponding to the pitch p calculated by the surface shape estimating unit 36 at any time, and if the amplitude at the pitch 25 mm of the evaluation target roll is less than 3.0 μm, If it is 3.0 μm or more, it is determined to be unsuitable (failed).
The judgment result by the conformity judgment section 37 is displayed on the display device 38 .

In this example, when the total rolling weight of the metal strip S reached 50,000 tons, it was estimated that the amplitude at the pitch of the evaluation target roll of 25 mm was 3.0 μm, so the conformity determination unit 37 determined that it was not conforming. Then, the judgment result was displayed on the display device 38 . Therefore, the operator temporarily stopped rolling based on the determination result displayed on the display device 38 . After that, when the operator pulled out the upper backup roll 2 of the third stand F3 from the stand F3 and measured the surface shape, the amplitude at the pitch of 25 mm was 3.2 μm, and the nonconformity of the roll to be evaluated was accurately determined. It was confirmed that the decision was made.

On the other hand, after replacing the upper and lower backup rolls 2 and the upper and lower work rolls 1 of the stand F3 with newly ground rolls, the metal strip S was rolled in the same manner as above. At that time, not only the backup roll 2 on the upper side of the stand F3 but also the backup roll 2 on the lower side of the stand F3 are included in the rolls to be evaluated. bottom.

Then, the same metal strip S as described above is continuously rolled as a material to be rolled, and the surface shape of either the upper backup roll 2 or the lower backup roll 2 of the third stand F3, which is the roll to be evaluated. When the amplitude corresponding to the pitch of 25 mm exceeded 2.5 μm, the upper backup roll 2 and the lower backup roll 2 of the stand F3 were replaced with new ground rolls to continue rolling the metal strip S. . As a result, the generation rate of chatter marks on the metal strip S was reduced by about 70% compared to the conventional operating method in which backup rolls are replaced when the total rolled weight reaches a preset value.

1 work roll (rolling roll)
2 Backup roll (rolling roll)
3 Intermediate roll (rolling roll)
4 Housing 5 Vibration Meter 6 Rolling Load Detector 7 Plate Thickness Gauge 8 Tension Meter Roll 9 Work Roll Driving Device 10 Roll Gap Controller 11 Roll Speed Controller 12 Controller for Control 13 Computer for Control 14 Host Computer 21 Chuck 22 Rest 23 Roll Rotating device 24 Tailstock 25 Motor 26 Displacement gauge 27 Measuring instrument logger 30 Suitability determination device for rolling rolls 31 Operation data acquisition unit 32 Rolling load data acquisition unit 33 Peripheral speed data acquisition unit 34 Vibration analysis unit 35 Initial surface shape acquisition unit 36 Surface shape estimation unit 37 Conformity determination unit 38 Display device 41 to 45 Spring 46 Damping element 51 to 57 Spring 58 Damping element a Rolling mill F1 to F5 Stand S Metal strip

Claims

In a rolling mill comprising one or more stands each having a plurality of rolling rolls, a rolling roll selected arbitrarily from the plurality of rolling rolls of an arbitrary stand to determine the suitability of a roll to be evaluated. A conformity determination method,
A rolling load data acquisition step of acquiring operation data of the rolling load of the stand having the roll to be evaluated;
A peripheral speed data acquisition step of acquiring operation data of the peripheral speed of the roll to be evaluated;
A vibration analysis step of analyzing the vibration behavior of the stand using the rolling load operation data of the stand having the evaluation target roll acquired in the rolling load data acquiring step;
The surface shape of the roll to be evaluated is obtained from the analysis result of the vibration behavior of the stand having the roll to be evaluated by the vibration analysis step and the operation data of the peripheral speed of the roll to be evaluated acquired in the peripheral speed data acquisition step. A surface shape estimation step for estimating during rolling of
a suitability determination step of determining suitability of the evaluation target roll based on the surface shape of the evaluation target roll estimated by the surface shape estimation step;
A method for determining suitability of a rolling roll, comprising:
An initial surface shape acquisition step of acquiring an initial surface shape of the evaluation target roll before the evaluation target roll is incorporated in a stand with the evaluation target roll,
In the surface shape estimation step, in addition to the analysis result of the vibration behavior of the stand having the evaluation target roll in the vibration analysis step and the operation data of the peripheral speed of the evaluation target roll acquired in the peripheral speed data acquisition step, The rolling roll according to claim 1, wherein the surface shape of the evaluation target roll is estimated during rolling of the metal strip using the initial surface shape of the evaluation target roll acquired in the initial surface shape acquisition step. Conformance judgment method.
3. The method of determining suitability of a rolling roll according to claim 1, wherein the surface shape of the roll to be evaluated is amplitude information associated with a pitch of irregularities formed on the surface of the roll to be evaluated. .
Analysis of the vibration behavior of the stand with the roll to be evaluated by the vibration analysis step uses a rolling mill vibration model that approximates the stand with the roll to be evaluated by a mass-spring system, and the spring constant in the rolling mill vibration model is The frequency response is calculated when a virtual external force is applied to the rolling mill vibration model in which the spring constant is updated according to the operation data of the rolling load of the stand having the roll to be evaluated. 4. The method for judging conformity of rolling rolls according to claim 1, characterized in that:
When the suitability determination of the evaluation target roll is performed during rolling of the metal strip using the method for determining suitability of the rolling rolls according to any one of claims 1 to 4, and the result of the suitability determination is unsatisfactory, A method of rolling a metal strip, wherein the roll to be evaluated is replaced with a new roll to roll the metal strip.
A method for manufacturing a cold-rolled steel sheet, which comprises manufacturing a cold-rolled steel sheet using the metal strip rolling method according to claim 5.