JPS6320606B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for controlling the shape of a steel plate when accelerating or decelerating the rolling speed of a rolling mill. The purpose is to correct the.

Recently, requirements for the quality of cold-rolled thin steel sheets have become increasingly strict, and it is required to improve the accuracy of the sheet thickness in the longitudinal direction and to manufacture flatter sheets without ear waves or elongation.

Conventionally, in order to meet this type of demand, in order to manufacture plates that are flat in the width direction and have good thickness accuracy,
It is already well known to attach a roll bending device between upper and lower work rolls in order to crown a work roll or correct deflection of the work roll.

Furthermore, a six-stage mill equipped with a mechanism for moving the intermediate roll in the sheet width direction has a more excellent shape correction effect.

Generally, when modifying the shape of a steel plate using these actuators, as shown in Figure 1, the output of the shape detector 4 installed on the final stand of a tandem mill, or on the exit side of the mill in the case of a lever mill, is used as shown in Figure 1. Techniques have been used in which the roll bending pressure and intermediate roll position are controlled by feedback, or the actuator is operated by visual inspection by an operator.

That is, in the case of the conventional example shown in FIG. 1, a steel plate 10 rolled by a tandem mill in which a back-up roll 1 is attached to a work roll 2 is guided by a deflector roll 8 and wound onto a tension reel 9. However, a shape detector 4 is installed on the exit side of the final stand of the tandem mill.
The shape of the rolled steel plate 10 is monitored.

The amount of deformation of the steel plate 10 from the set shape detected by the shape detector 4 is input to the calculation device 5, and a control amount corresponding to the amount of deformation is calculated.

The control amount from the calculation device 5 is determined by each work roll 2.
The rolling pressure of the work roll 2 is inputted to a bending pressure control device 6 connected to the bending pressure control device 6, and the rolling pressure of the work roll 2 is controlled in a direction that corrects the deformation of the steel sheet 10.

Further, a 6 having an intermediate roll 3 shown in FIG.
In the case of a corrugated mill, an intermediate roll position control device 7 is additionally provided in the case shown in FIG.

By the way, in both tandem mills and liver mills, when the rolling speed is accelerated, the oil film thickness of the roll bearing changes, and the rolling load increases. Furthermore, the deformation resistance of the steel plate 10 increases under the influence of the strain rate, which also tends to increase the rolling load.

Therefore, during acceleration, the steel plate 10 tends to be deformed by elongation.

On the other hand, when the rolling speed is decelerated, the rolling load decreases, which is completely opposite to when the rolling speed is accelerated, so that the deformation tends to be a stretch.

When the steel plate 10 is deformed due to this change in rolling speed, the shape detector 4 conventionally detects the deformation of the steel plate 10.
The actuator was operated by detecting the deformation of the roll and feeding back the output of the shape detector 4, but the shape detector 4 currently developed and put into practical use has a large time constant. Since it is impossible to sufficiently follow changes in the shape of the object, shape modification cannot be achieved satisfactorily.

That is, the acceleration/deceleration time of the rolling speed is about 10 to 20 seconds, but with the shape detector 4 for the steel plate 10 currently in practical use, it takes about 2 to 3 seconds to detect the shape with high precision. Since a sampling period is required and the device is installed far from the rolling mill, a response delay inevitably occurs. It has been impossible to modify the changing shape in a responsive manner.

The present invention was devised to satisfy the above-mentioned conventional requirements and eliminate the dissatisfaction in the conventional example, and the deformation pattern of the steel plate 10 due to acceleration/deceleration of the rolling speed tends to be constant, and the plate of the intermediate roll Focusing on the fact that the displacement in the width direction has the ability to correct the shape of the steel plate 10 by compensating for the deformation pattern of the upper steel plate 10, the shape of the steel plate is corrected by changing the intermediate rolls in accordance with changes in acceleration/deceleration of the rolling speed itself. This is how it was done.

Hereinafter, the present invention will be explained with reference to FIGS. 3 to 7.

In addition, in the figure, the same reference numerals as those in FIGS. 1 and 2 indicate the same parts.

A method for controlling the shape of a steel plate during acceleration and deceleration of rolling according to the present invention is a method for controlling the shape of a steel plate during acceleration and deceleration of rolling in a rolling mill having a mechanism for moving an intermediate roll 3 in the width direction of the steel plate 10, that is, an intermediate roll position control device 7. The speed change is detected by the speed meter 20, and according to the detected speed change amount, the displacement Hcδ (second (see Figure 4) is controlled to increase or decrease by the intermediate roll position control device 7 in such a direction that it decreases as the rolling speed increases and increases as the rolling speed decreases.

Generally, in a mill for cold rolling steel sheets with oil film bearings, when the rolling speed increases by 1000 m/min, the rolling load increases by about 100 tons, as shown in FIG.

Further, the relationship between the rolling load and the shape of the steel plate (the amount of edge elongation deformation) is approximately linear, as shown in FIG. 6, and as the rolling load increases, the shape of the steel plate 10 changes in the edge elongation direction. The amount of edge elongation deformation varies depending on the sheet width, sheet thickness, rolling speed, initial load, etc.

Furthermore, the displacement amount Hcδ of the intermediate roll 3 is equal to the steel plate 10.
The shape modification effect given to the shape is that the amount of displacement of the intermediate roll 3 and the amount of shape change (edge elongation deformation) of the steel plate 10 are approximately in a linear relationship as shown in FIG. Become.

With these things, if the intermediate roll position control device 7 is controlled in the direction of decreasing the displacement amount Hcδ in accordance with the increase in the rolling speed, it is possible to eliminate the shape change of the steel plate 10 due to an increase in the rolling load, and similarly,
If the intermediate roll position control device 7 is controlled in the direction of increasing the displacement amount Hcδ in accordance with the decrease in the rolling speed,
Changes in shape of the steel plate 10 due to reduction in rolling load can be eliminated.

In FIGS. 3 and 4, a speedometer 20 is installed to detect the rotational speed of the work roll 2 in the final stand, and by detecting the rotational speed of the work roll 2, changes over time in the rolling speed can be detected. There is.

Changes over time in the rolling speed detected by the speedometer 20, that is, changes in acceleration and deceleration, are sent to the calculation device 30.
This calculation device 30 calculates the amount of change in the rolling load that increases or decreases in response to the change in rolling speed, that is, the degree of acceleration/deceleration, and further calculates the amount of displacement Hcδ of the intermediate roll 3 corresponding to the amount of change in the rolling load. Then, the calculated amount signal is outputted to the intermediate roll position control device 7 as a control signal.

The calculation contents in this calculation device 30 include the relationship between the rolling speed change and the rolling load change described above, the relationship between the rolling load change and the shape change of the steel plate 10, and the displacement amount Hcδ of the intermediate roll 3 and the shape of the steel plate 10. As is clear from the relationship with the change, if the rolling load that changes due to the change in rolling speed is △P,
△P is expressed as △P=f(P ₀ , V _R ) (1) where P ₀ is the set load and V _R is the rolling speed.

Furthermore, when the rolling load △P changes, the amount of correction △Hcδ of the displacement amount Hcδ of the intermediate roll 3 to be corrected
is expressed as △Hcδ=F(△P)...(2).

Therefore, the calculation device 30 finally calculates the correction amount ΔHcδ of the intermediate roll 3 according to equation (2), and outputs the result to the intermediate roll position control device 7.

In addition, by combining equations (1) and (2), △Hcδ=G (P ₀ , V _R ) ...(3), and the correction amount △Hcδ can be calculated directly from the set load (initial load) and rolling speed. It may also be possible to calculate.

By the way, as mentioned above, the amount of shape deformation of the steel plate 10 due to an increase or decrease in the rolling load △P varies depending on the width and thickness of the steel plate 10, the rolling speed V _R , the initial load P ₀ , etc., so the correction amount △Hcδ (1), (2) to determine
Further, the various coefficients included in equation (3) are determined by considering the influence coefficient of the rolling load △P on the steel plate shape, the influence coefficient of the intermediate roll 3 correction amount △Hcδ on the steel plate shape, etc. They are classified according to width, thickness, rolling speed V _R , initial load P ₀ , etc.

Note that since the method of the present invention is based on a feed-forward method, errors may occur on the prediction side, but in such cases, correction can be made using feedback control using the shape detector 4. Can be done.

Further, in the embodiment shown in FIGS. 3 and 4, the rolling speed is detected from the rotation of the work roll 2, but the rolling speed is detected from the rotation of the work roll 2.
It goes without saying that the speed of the steel plate 10 is not limited to this, and that the speed of the steel plate 10 may be directly detected with a non-contact speed meter.

As described above, the present invention uses a calculation device to calculate the relationship between the amount of change in rolling load caused by changes in oil film thickness and changes in strain rate caused by changes in rolling speed, rolling speed, and optimal displacement amount of intermediate roll 3. 30, input the change in rolling speed to this calculation device 30, and immediately change the correction amount △ of the intermediate roll 3.
Since Hcδ is calculated and the displacement amount Hcδ of the intermediate roll 3 is corrected, the position of the intermediate roll 3 can be corrected in a sensitive manner to changes in the rolling speed, and changes in the shape of the steel plate 10 due to changes in the rolling speed can be quickly corrected. This means that it can be corrected.

In addition, when used in combination with a conventional shape detector, it compensates for the slow response of the shape detector while maintaining the reliable and accurate shape correction ability of the shape detector, allowing for quick shape correction. This means that any shape modification of the steel plate can be accomplished more accurately and quickly.

As is clear from the above explanation, the method of the present invention exhibits extremely excellent shape correction responsiveness to acceleration and deceleration of the rolling speed, and this excellent responsiveness improves rolling quality and saves labor. It has many excellent effects, such as greatly contributing to improving the quality of products.

[Brief explanation of the drawing]

1 and 2 are simplified configuration diagrams for explaining a conventional shape control method. FIG. 3 is a simple side configuration diagram for explaining one embodiment of the present invention. FIG. 4 is a front configuration diagram of the same. Figure 5 shows
It is a roll speed-rolling load characteristic diagram. FIG. 6 is a rolling load-steel plate shape (elongation deformation) characteristic diagram. FIG. 7 is a characteristic diagram of the displacement of the intermediate roll versus the shape of the steel plate (extension deformation). Explanation of symbols, 2: Work roll, 3: Intermediate roll, 4: Shape detector, 5: Arithmetic device, 7: Intermediate roll position control device, 10: Steel plate, 20: Speed meter,
30: Arithmetic device.

Claims (1)

[Claims] 1. In a rolling mill having a mechanism for moving intermediate rolls in the sheet width direction, speed changes during acceleration and deceleration of the rolling speed are detected, and one side end of the intermediate roll and the same side of the steel sheet are detected according to the amount of speed change. reducing the amount of displacement between the side edges as the rolling speed increases;
A method for controlling the shape of a steel plate during acceleration and deceleration of rolling, which controls increases and decreases in the direction of increasing rolling speed.