JPH08257612A - Shape control method of rolled material in rolling mill - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a method for controlling the shape of a rolled material in an inexpensive and highly responsive rolling mill that does not require expensive equipment and a large space and has no detection time delay. [Structure] The shape ε of rolled material is expressed by the following relational expression (1) between the operation amount xi of each shape control actuator and the rolling load P. The coefficients ai, b and c of the relational expression (1) are calculated from the dimensions and material specifications of the rolled material before the rolling of the rolled material is started. Operation amount x of shape control actuator during rolling of rolled material x
i and the rolling load P are measured, and the shape ε of the rolled material is calculated by the following relational expression (1). The shape ε of the rolled material obtained above is the target shape ε aim
The operation amount xi of the shape control actuator that satisfies the above equation is calculated by the following relational expression (1). Correct the manipulated variable xi of the shape control actuator. ε = Σai · fi (xi) + b · P + c ...
(1) (i = 1 to n)

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling the shape of a rolled material in a rolling mill having a shape control actuator for controlling the shape of the rolled material for rolling a metal strip.

[0002]

2. Description of the Related Art In a rolling mill for rolling a metal strip, as a method for controlling the shape of the rolled material, a shape detector is provided on the rolling-out side of the rolling machine to provide a shape of the rolled material (flatness, plate crown) during rolling. Etc.), and based on the measured value, a shape control actuator such as a roll bending device, a roll cross device, an intermediate roll shift device and a variable crown device is operated to set a rolling shape to a target shape. . This method has a drawback in that detection is delayed because the point measured by the shape detector is a point distant from the rolling mill, and control of high response is difficult. Further, in a tandem rolling mill having a plurality of rolling stands, it is difficult to install the shape detectors on all of the rolling stands on the outgoing side in the rolling direction in terms of equipment cost and physical space.

As a method for solving these problems, there is a method disclosed in Japanese Patent Application Laid-Open No. 57-7309. In this method, based on the idea that the main cause of the shape change of the rolled material is the fluctuation of the rolling load, the rolling load is measured during the rolling of the rolled material to obtain the fluctuation amount of the rolling load, which results from the fluctuation of the rolling load. This is a method of operating the shape control actuator by calculating the operation amount (roll bending force) of the shape control actuator such as a roll bending device that corrects the shape change.

[0004]

However, in the above-mentioned shape control method, when obtaining the variation of the rolling load,
The rolling load at the start of control is stored as a reference value, and the amount of change from this rolling load reference value is calculated. Therefore, in order to operate the shape control actuator so as to correct the shape change due to the rolling load fluctuation after the storage timing,
If the rolling shape of the rolled material is not the target shape at the timing of storing the rolling load reference value, the control operation is performed so as to maintain the deviated shape. In particular, when passing the strip at the leading end of the strip to be rolled, the strip passability may be given priority, and the strip thickness of the strip does not reach the target value. In many cases, they do not match, and there is a problem that it is difficult to determine the storage timing (control start timing) of the rolling load reference value.

Further, for example, in a rolling mill equipped with a roll bending device as a shape control actuator, and a roll cross device for vertically crossing a work roll and a support roll as a pair in the up and down direction in a horizontal plane,
In some cases, the roll cross device is operated to adjust the roll cross angle in order to improve the flatness of the rolled material. However, with respect to the shape change due to the operation of the shape control actuator as in this example, the target shape cannot be obtained by the method of measuring only the rolling load and operating the roll bending force as described above.

The method of the present invention has been made in view of the above-mentioned problems of the prior art, and is for an inexpensive and highly responsive rolling mill that does not require expensive equipment such as a shape detector and a large space. It is an object to provide a shape control method for rolled material.

[0007]

SUMMARY OF THE INVENTION The present invention is a method for controlling the shape of a rolled material in a rolling mill having a shape control actuator for controlling the shape of the rolled material, the control method comprising the following steps. Is the gist.

The shape ε of the rolled material is expressed by the following relational expression (1) between the operation amount xi of each shape control actuator and the rolling load P.

The coefficients ai, b and c of the relational expression (1) are determined from the dimensions and material specifications of the rolled material (plate width, plate thickness, material, etc.) before starting rolling of the rolled material.

During rolling of the rolled material, the operation amount xi of the shape control actuator and the rolling load P are measured, and the shape ε of the rolled material is calculated by the following relational expression (1).

The manipulated variable xi of the shape control actuator such that the shape ε of the rolled material obtained above becomes the target shape ε aim is recalculated by the following relational expression (1).

The manipulated variable xi of the shape control actuator is corrected.

Ε = Σai · fi (xi) + b · P + c ··· (1) (i = 1 to n)

[0014]

There are various factors that affect the flatness of the rolled material and the shape of the plate crown, etc.
It is classified into one that is determined by the rolled material such as strip width and material, and one that is determined by the rolling condition such as the rolling load and the operation amount of the shape control actuator. Among them, the strip width and the material are almost constant during rolling. The plate thickness is the most rigorously handled quality item, and is usually controlled to a predetermined value by a plate thickness control device or the like. Therefore, the main factors that cause the shape change during rolling are the rolling load and the manipulated variable of the shape control actuator.

Representative examples of the operation amount of the shape control actuator include a roll bending force and a roll cross angle, which will be described later, a roll shift amount of an intermediate roll, a crown adjusting pressure of a variable crown device, and the like.

When the rolling load changes, the roll deflection due to the rolling reaction force changes, so the shape of the rolled material changes, but this relationship is almost linear.

Therefore, when there are shape control actuators 1 to n, the shape ε of the rolled material can be expressed by the following equation (1).

Ε = Σai · fi (xi) + b · P + c (1) (i = 1 to n) where a1 to an, b and c are the width, thickness and material of the rolled material. Is a constant determined by the dimensions and material specifications of
fi (xi) is the operation amount x of the i-th shape control actuator
It is a function of i only.

Hereinafter, the method of the present invention will be described based on a concrete embodiment in which it is carried out by a four-high rolling mill consisting of work rolls and rolling rolls shown in FIG. Here, a roll bending device 5 is used as the shape control actuator, and a roll cross device for vertically pairing the work roll 2 and the support roll 3 in pairs in the vertical direction is used.

As shown in FIG. 2, the roll bending force changes the shape of the rolled material by changing the roll deflection like the rolling load. The roll bending force F applied to the roll chock 4 and the rolled material shape ε. Is a linear relationship. On the other hand, as shown in FIG. 3, the roll cross device changes the roll cross angle θ to change the width direction distribution of the roll gap to change the shape of the rolled material. It is known to be proportional to the square of.

From the above, the shape ε of the rolled material is (1)
From the equation and the above relation, it can be expressed by the following equation (2).

[0022] ε = a1 · F + a2 · θ 2 + b · P + c ··· (2) P: rolling load, F: roll bending force, theta: roll cross angle where coefficients a1, a2, b and c are plate thickness , Is a constant determined by the rolled material such as strip width and material, and may be obtained in advance for each coil to be rolled from past results by a statistical method or the like, or may be calculated using a theoretical rolling formula.

In order to control the shape of the rolled material to the target shape ε aim, the roll bending force F and the roll cross angle θ may be manipulated so that ε = ε aim in equation (2). Since the response is faster than that of the cross device, it is desirable to operate the roll bending force F ′ according to the rolling load P during rolling and the roll cross angle θ by the formula (3).

F ′ = (εaim −a ² · θ ² −b · P−c) / a 1 (3) As described above, the coefficients a 1, a 2, b and c are obtained in advance before starting rolling. Therefore, during rolling, the calculation of the formula (3) needs only simple four arithmetic operations, and the control cycle can be shortened.

As an embodiment for explanation, a four-high rolling mill consisting of a single stand was used, but the present invention is not limited to this. It goes without saying that the same effect can be obtained even when applied to a rolling mill.

Similarly, although the roll bending device and the roll cross device have been described as examples of the shape control actuator, other devices such as a roll axial shift device and a variable crown device may be used. In this case, assuming that the operation amount of each shape control actuator is the shift amount Ls of the intermediate roll or the crown adjustment pressure Pc, the linear relationship between the shape ε and these actuator operation amounts Ls, Pc is used to make the above-mentioned relationship. Let the fi (xi) term of the equation (1) be fs (Ls) or fc (Pc), and the following (4)
It is realized by applying the equation or the equation (5).

Fs (Ls) = Ls ... (4) fc (Pc) = Pc .... (5)

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to the drawings showing the embodiments.

FIG. 1 shows the 4 used in carrying out the method of the present invention.
It is a schematic diagram of a multi-stage rolling mill and a block diagram of a shape control device.

The rolling mill is a four-high rolling mill consisting of work rolls 2 and support rolls 3, and the rolled material 1 is rolled by the work rolls 2 to a predetermined plate thickness. Roll bending device 5 and work roll 2 as a shape control actuator
A roll cross device (not shown) for vertically crossing the support roll 3 and the support roll 3 as a pair is provided.

The coil information transmitter 30 is a rolled material (coil).
The coil information transmitter 30 outputs this information to the computer 40. In the computer 40, the shape ε of the rolled material is calculated in advance by the roll bending force F which is the operation amount of the shape control actuator, the roll cross angle θ and the rolling load P.
The coefficients (a1, a2, b and c) expressed by the relational expression (2) are obtained from past results by a statistical method and stored in the form of a table for each target rolling material group. . In the calculator 40, a predetermined coefficient is selected from the coefficient table based on the coil information such as the strip width, strip thickness and material before and after rolling obtained from the coil information transmitter 30 and input to the roll bending force calculator 50. To do.

During rolling of the rolled material 1, the rolling load P is measured by the load cell 10, the roll bending force F is measured by the roll bending force measuring device 20, and the roll cross angle θ is measured by the roll cross angle detector 15. It is input to the bending force calculator 50. The roll bending force calculator 50 calculates the coefficient (a1, a2, b and c) of the relational expression input from the computer 40 and the load cell 10
Based on the rolling load P input from the roll bending force measuring device 20, the roll bending force F input from the roll bending force measuring device 20, and the roll cross angle θ input from the roll cross angle detector 15, the shape of the rolled material 1 is the target shape. A roll bending force F ′ that gives ε aim is calculated by the equation (3) and input to the roll bending device 5, and the roll bending device 5 is configured to control the roll bending force F to this input value.

The above-mentioned shape control device is installed on the first to fourth stands of a 5-stand cold continuous rolling mill in actual operation, and a low carbon steel plate (sheet thickness 0.4 to 2.5 mm) is finished with ε aim = 0. When rolling was performed, excellent responsiveness and rolling shape control results with shape accuracy comparable to that obtained by the conventional shape control device using a large-scale shape detector were obtained.

Conventionally, in any of the first to fourth stands where the shape control device is not installed, the shape may be defective and the plate may be broken. However, by carrying out the method of the present invention, the plate is caused by the same kind. The number of ruptures was drastically reduced, and the total plate rupture accident was reduced by half.

[0035]

According to the method of the present invention, the amount of operation of the shape control actuator and the rolling load are measured, and the shape of the rolled material is calculated by the relational expression determined before the start of rolling. It is possible to control the shape of a rolled material at a low cost and with high response without requiring expensive equipment such as a shape detector and a large space, and having no detection time delay.

[Brief description of drawings]

FIG. 1 is a schematic view of a rolling mill and a block diagram of a shape control device used when carrying out the method of the present invention.

FIG. 2 is an explanatory diagram of a roll bending force F used as one of the operation amounts of the shape control actuator when carrying out the method of the present invention.

FIG. 3 is a roll cross angle θ used as one of the manipulated variables of the shape control actuator when carrying out the method of the present invention.
FIG.

[Explanation of symbols]

 1 Rolled material 2 Work roll 3 Support roll 4 Roll chock 5 Roll bending device 10 Load cell 15 Roll cross angle detector 20 Roll bending force measuring device 30 Coil information transmission device 40 Computer 50 Roll bending force calculator

Claims (1)

[Claims] 1. A method for controlling the shape of a rolled material in a rolling mill having a shape control actuator for controlling the shape of the rolled material, wherein the shape ε of the rolled material is defined by an operation amount xi of each shape control actuator and a rolling load P. The following relational expression (1)
The relational expression (1) is calculated from the dimensions and material specifications of the rolled material.
The coefficients ai, b and c of
Operation amount xi of shape control actuator during rolling of rolled material
And the rolling load P is measured, the shape ε of the rolled material is calculated by the following relational expression (1), and the obtained shape ε of the rolled material is calculated.
The shape control method of the rolling mill is characterized in that the operation amount xi of the shape control actuator such that the target shape ε aim is recalculated by the following relational expression (1), and the operation amount xi of the shape control actuator is corrected. ε = Σai · fi (xi) + b · P + c ··· (1) (i = 1 to n)