JPS5825808A - Controlling method of sheet thickness at pass-through and run-out in rolling mill - Google Patents

Abstract

PURPOSE:To significantly decrease off-gauge length and to improve the product yield, by previously deciding a sheet-thickness controlling pattern capable of making the off-gauge length minimum in accordance with rolling conditions, etc. in experiential and experimental manners. CONSTITUTION:A target sheet-thickness pattern required to decrease the off- gauge length at the top and bottom parts, etc. of a material to be rolled, measured at the point of time when a finish rolling of the material is completed, as much as possible is previously set based on the various dimensional units or rolling conditions, etc. Then in rolling the material, press-down positions are controlled so as to coincide with the target pattern. Thus the sheet thickness at the time of pass-through and run-out in a rolling mill, is controlled so as to decrease the off-gauge in rolling and to significantly improve the product yield.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for controlling plate thickness in a cold continuous rolling mill, particularly during threading and ash removal in a rolling mill, in order to finish the top and bottom parts of a rolling coil to a target thickness. It is related to.

The most important control item when manufacturing cold-rolled steel sheets is plate thickness accuracy, and automatic plate thickness control technology, so-called A, is used to improve plate thickness accuracy.
Various GC techniques have been developed. By the way, if we look at the rolling speed of the rolling process using a cold continuous rolling mill (hereinafter simply referred to as a tandem mill) K, we can see that generally when the sheet is passed at a low rolling speed in which the top of the hot-rolled coil, which is the raw material, is bitten into the rolling mill, It is classified into three periods: acceleration, when the rolling speed is increased to a higher steady rolling speed; deceleration, when the rolling speed is decreased from the steady rolling speed; and ash removal, when the coil bottom is removed from the rolling mill at a low rolling speed. be done. Since most of the nine-deck coils are rolled at normal speeds, most of the AGC techniques are aimed at the above-mentioned steady rolling, and are not intended for other low-speed threading, acceleration, or deceleration. There is almost nothing to do. In order to compensate for this, the usable range of normal AGC has been expanded to a rolling speed range of +96 to 20% of the steady rolling speed, and at lower speeds the operator manually controls the plate thickness. This is the current situation.

However, with this method, the plate thickness does not fall within the target plate thickness.
The so-called off-gauge portion tends to be long, and a decrease in yield due to the truncation of this off-gauge portion is unavoidable. One of the reasons why such off-gauge occurs is, for example, during strip threading.After the top of the rolled coil leaves the first stand, until it is bitten by the next stand adjacent to it, the front part of the strip is Rolling is sometimes performed in a state of zero tension, where no tension is applied at all. In other words, in the intermediate part of the rolling coil, rolling is performed with the forward and backward tensions generated between adjacent stands applied, whereas in the dog part of the rolling coil, the forward tension applied between adjacent stands is applied to each stand. As a result, the time required for rolling coils to be exposed to the rolling coil becomes shorter toward the top portion compared to other intermediate portions, and this condition is repeated between each adjacent stand, resulting in the plate thickness at the top portion of the rolled coil becoming thicker than other portions. It's about putting it away. This situation also applies to the bottom part of the rolling coil during ash removal, and an off-gauge part occurs because it is not subjected to rear tension. Another cause of off-gauge as described above, which mainly occurs during rolling of thin rolled coils, may be due to instability of the rolled coils being jammed into each stand during threading. In this case, in order to make it easier for the rolling coil to be caught in each stand, the rolling position of each stand, in other words, the roll gap, is adjusted as necessary, resulting in uneven plate thickness. This is due to the fact that the off-gauge length becomes large.

The present invention has been developed in view of the above circumstances, and its purpose is to reduce the off-gauge length at the top, bottom, etc. of the rolled material at the time when the rolled material is finished rolled. The target plate thickness pattern necessary to achieve a reduction in thickness is set in advance based on the dimensional specifications of the material to be rolled, rolling conditions, etc., and when rolling the material to be rolled, the target thickness pattern is matched to the target plate thickness pattern. To provide a method for controlling sheet thickness during sheet threading and tail removal of a rolling mill, which controls the rolling position etc. so as to reduce off-gauge and significantly improve yield.

The method of controlling plate thickness during sheet passing and ash removal in a rolling mill according to the present invention is to set a target plate thickness pattern in advance for the direction of force at the top or bottom part of the material to be rolled, and Alternatively, during rolling of the bottom part, the gauge meter plate thickness of each part in the longitudinal direction is calculated based on the rolling position and rolling load, and the rolling position is adjusted so that the plate thickness pattern based on the gauge meter plate thickness matches the target plate thickness pattern. In addition, the gauge meter plate thickness is calibrated based on the detected value of a thickness gauge installed on the exit side of the rolling mill.

First, the theory of the plate thickness control method according to the present invention (hereinafter referred to as the method of the present invention) will be explained below. Figure 1 (a), (b)
, C are schematic diagrams showing an example of the target plate thickness pattern for the top part of the coil, which is the material to be rolled, for the Ii1 stand, and FIG. Figure 1 (b) shows the target thickness pattern X of the coil at the exit side of the rolling mill.
The target plate thickness pattern Y, which is set to be thinner than o, is
Furthermore, Fig. 1 e9 shows the target thickness pattern Z of the coil at the exit side of the rolling mill, which is set to be thicker than 0.
An example is shown.

As described above, the target plate thickness pattern is determined empirically and experimentally so that the off-gauge length of the top portion at the end of finish rolling can be shortened as much as possible. For example, the target plate shown in Figure 1 (→) is effective when rolling a thick coil top part, and the one shown in Figure 1e is effective when rolling a thin coil top part. The thickness pattern shown in FIG. 1(a) is a target plate thickness pattern used for general coil rolling other than the above.

Of course, the single standard I plate thickness pattern as described above varies depending on the coil dimensions and rolling conditions, and the target plate thickness pattern for each coil dimension and rolling condition is determined in advance. First, select the optimal target plate thickness pattern that can reduce the off-gauge length as much as possible for each dimension specification and rolling condition,
The plate thickness of each part in the longitudinal direction of the coil top section given by this target plate thickness pattern is set as the target plate thickness using an absolute value gauge meter AGC
trol). That is, based on the selected target plate thickness pattern, the rolling position and rolling load are detected to achieve this, the gauge meter plate thickness given by the following formula (1) is calculated, and this gauge meter plate thickness hK is calculated. The rolling position, roll speed, etc. are controlled so that the plate thickness pattern of the coil top portion of the rolling configuration example matches the target plate thickness pattern.

h = S+So+P/M+S, r...(1)
However, So: Initial setting value of the rolling position S: Rolling position P: Rolling load M: Mill rigidity SoF: Thickness of the oil film on the backup roll bearing The thickness of the gauge meter plate is determined by the roll speed vK detected using a tacho generator, etc. Calculate the coil speed at the exit side of each stand by adding the advancement rate f of the stand, find the length from the coil top after the coil is bitten by the stand, and calculate the length at the predetermined timing for each part in the longitudinal direction of the coil top part. Determine the thickness pattern of the gauge meter plate thickness.

Next, a case in which the method of the present invention is applied to a 5-stand cold tandem mill will be specifically explained.

Figure 2 is a schematic diagram showing a 5-stand cold tandem mill to which the method of the present invention is applied and its control system.
T1. S Tt , S Ts , S T4 ,
S Ts is the stand, X, X, -X is the X-ray thickness gauge, MM, MM, MM.

is a mill motor, TG, TG,...TG is a tacho generator, LC,, LC,...LC is a load cell, swl, sw.

...SW indicates the screw lowering motor and the coil which is the ch rolled material. The coil C is threaded through each of the stands ST□ to ST from the direction of the white arrow, and during the threading, the board thickness is controlled as described below. The plate thickness control to be applied to each strip in each stand is basically the same, and the control mode in stand ST1 will be explained below. In the figure, reference numeral 1 denotes an arithmetic control unit r, which contains the initial set value of the rolling position, that is, the data for the zero point 56KIQ, and the oil film thickness 5 (IPK) on the backup roll.
The related data is input, and the load cell LC1
From then on, data regarding the rolling load P1, data regarding the currently set rolling down position StK from the rolling position detector 2, and data regarding the speed of the mill motor MM1 from the tacho generator TG are read in sequence at predetermined timing, and the
1) Based on the formula, the gauge meter plate thickness h1 of each part in the longitudinal direction from the coil top part is calculated and outputted to the rolling position control device 2.

Reference numeral 3 denotes a target plate thickness pattern generator, into which the target plate thickness patterns x, y, z, etc. for each of the various rolling conditions determined in advance, as described above, are inputted. When an appropriate target plate thickness pattern is selected, data regarding the rotation speed of the mill motor MM is read from the tachogenerator TG, and the coil top section is set to the first
Stand ST.

In synchronization with the rolling position, the target plate thickness of each part corresponding to the rolling position from the coil top part is output to the rolling position control device 2. Press down position control device 2 Gauge meter thickness input from the arithmetic and control device 1.

and the target plate thickness h1 inputted from the target plate thickness pattern generator 2, calculate the reduction position adjustment amount iS necessary to make the former match the latter, and issue a command signal to the reduction motor SW1. It is.

On the other hand, the zero point S6 of the lowered position is determined as follows. That is, the arithmetic and control device 1 calculates the gauge meter plate thickness calculated based on the formula (1) above and the plate thickness hx measured when the part for which this gauge meter plate thickness was calculated reaches the thickness gauge. The control device i1 may compare and determine the zero point S0 so that the gauge meter plate thickness matches the plate thickness hX.

Note that if there is eccentricity in the roll of the first stand, an error will be included in the calculation of the gauge meter plate thickness, so the gauge meter plate thickness and the measured plate thickness h In order to improve accuracy, it is more desirable to determine the zero point based on the average data.

During coil rolling, the zero point S0 of the rolling position can be calculated continuously or at a fixed timing using the actual measurement data as described above, but it is possible to calculate the zero point S0 of the rolling position using the actual measurement data as described above. Although the zero point position changes due to a change in thermal expansion due to a change in roll temperature, it is not possible to calculate the zero point S in the manner described above. If rolling is temporarily interrupted, the upper and lower rolls are brought into direct rolling contact, the load cell LC1 is set to indicate a predetermined rolling edge, and the rolling load V and rolling position at that time are adjusted. 100 is detected and the zero point S0 of the lowered position is calculated.

After that, the rolling motor is operated to set the rolling position to the original position, and in preparation for the start of rolling, it is possible to automatically perform the above series of operations by simply turning on the start switch by the operator, which will prevent the rolling operation from occurring. It will never be.

Next, the rolling results obtained using the method of the present invention will be explained. The result is a finished material coil with a plate thickness of 2.6- and a plate thickness of 0.8.
This is for rolling to m. Fig. 3 (a) is a graph showing the results when the method of the present invention is applied, and Fig. 3 (b) is a graph showing the results when the conventional method is applied. The vertical axis shows the position in the longitudinal direction of the part, and the deviation of the plate thickness from the finished plate thickness is plotted on the vertical axis. As is clear from this graph, when the method of the present invention is used, the off-gauge (±5
0)1 or more) length is 5 m, whereas in the case of applying the conventional method, it reaches 11n4, and the method of the present invention is recognized to have a remarkable effect in shortening the off-gauge length.

As described above, in the method of the present invention, a plate thickness control pattern that can achieve the shortest off-gauge length is determined in advance according to rolling conditions, etc., and plate thickness control is performed to achieve this pattern. Since this is the case, the off-gauge length can be significantly shortened, and the yield rate can be improved accordingly.The present invention has excellent results.

[Brief explanation of the drawing]

$1 Figures (A), (→, and (C) are explanatory diagrams showing examples of target plate thickness patterns used in the method of the present invention, and Figure vIz is a schematic diagram showing a cold tandem mill to which the method of the present invention is applied and its control system. Figures 3(a) and 3(b) are graphs showing the plate thickness control effects of the method of the present invention and the conventional method. 1... Arithmetic control device 2... Rolling position control device 3.
...Plate thickness pattern generator C...Coil ST, ~S
T,...Stand x1~X,...Thickness MM,~
MM, ... Mill motor SW, ~SW, ... Pressure motor TG, -TG, ... Tacho generator LC,
~LC3...Load cell patent applicant Sumitomo Metal Industries Co., Ltd. Agent Patent attorney Noboru Kono (1) Figure 1 Figure 3

Claims (1)

[Claims] 1. A target plate thickness for the longitudinal force of the top or bottom of the material to be rolled is set in advance, and the rolling position and rolling load are adjusted during rolling of the top or bottom of the material to be rolled. A rolling mill characterized in that the gauge meter plate thickness at each part in the longitudinal direction on the exit side of the rolling machine is calculated based on the gauge meter plate thickness, and the rolling position is adjusted so that the plate thickness pattern based on the gauge meter plate thickness matches the target plate thickness pattern. Method for controlling plate thickness during plate threading and ash removal. 2. A target plate thickness pattern for the longitudinal force direction of the top or bottom part of the material to be rolled is set in advance, and during rolling of the top or bottom part of the material to be rolled, each part in the longitudinal direction is adjusted based on the rolling position and rolling load. The gauge make plate thickness at the exit side of the rolling mill is calculated, and the rolling position is adjusted so that the plate thickness pattern based on the gauge make plate thickness matches the target plate thickness pattern. A method for controlling plate thickness during plate passing and ash removal in a rolling mill, characterized in that calibration is performed based on the detected value of an installed thickness gauge.