JPH0698368B2 - Shape control method for cold rolling mill - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a shape control method for a cold rolling mill that controls the shape of a material to be rolled by controlling a coolant.

[Conventional technology]

In recent years, demands for shape accuracy of rolled products such as steel sheets have become strict. The thickness of the material to be rolled in the longitudinal direction is remarkably improved in accuracy by the thickness control device. On the other hand, the thickness in the width direction of the rolled material is roll bending control,
It is controlled by roll shift control and coolant control. The coolant control controls the amount of coolant supplied to the roll, and the time constant of shape control becomes large. This is described in JP-A-55-42162.

Since the coolant control divides the cooling range into a large number in the axial direction of the roll, it can handle complicated shapes. Conventionally, coolant control supplies a preset amount of coolant based on the actual shape.

[Problems to be Solved by the Invention]

The time constant of the coolant control is as very long as 1 minute to 5 minutes, and the roll bender control reaches the control limit and becomes saturated before the coolant control effect appears. Therefore, if the crown change interval of the material to be rolled is short, it cannot be controlled and the shape cannot be controlled accurately.

An object of the present invention is to provide a shape control method for a cold rolling mill, which can reduce the response time of coolant control and can perform shape control with high accuracy.

[Means for Solving the Problems]

According to the present invention, a region in which the roll crown variation with respect to the coolant amount is large, that is, the influence coefficient is large and is larger than the allowable minimum coolant amount is set as the coolant control range, and the coolant amount is controlled within this coolant control range.

Further, according to the present invention, when performing the coolant control, the forcing control is performed so as to make the maximum coolant flow rate or the minimum coolant flow rate within the coolant control range.

[Action]

Since the coolant flow rate is controlled in the region where the roll crown changes greatly, the control time constant can be accelerated and the roll thermal crown changes can be sufficiently followed. Therefore, it is possible to follow the change of the crown of the material to be rolled, and the shape control can be performed with high accuracy.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of the present invention, showing an example of a six-fold rolling mill.

In FIG. 1, a material 8 to be rolled is rolled by a rolling roll of a six-fold rolling mill 1 and wound on a tension reel (not shown) via a roll 7. The six-fold rolling mill 1 includes a pair of work rolls 2A and 2B, a pair of intermediate rolls 3A and 3B, and a pair of backup rolls 4A and 4B.

Although not shown in FIG. 1, as shown in FIG. 2, it has a bending device 11 for controlling the bending force of the work rolls 2A, 2B and a bending device 12 for controlling the bending force of the intermediate rolls 3A, 3B.

The intermediate rolls 3A and 3B can normally be shifted in the roll axial direction in order to increase the bending effect. 5A and 5B are coolant devices for the work rolls 2A and 2B, and as shown in FIG. The shape of the material 8 to be rolled is detected by the shape detector 14 provided on the exit side of the rolling mill 1. The target shape signal set in the target shape setter 21 and the actual shape signal detected by the shape detector 14 are compared, and the control calculator
Enter in 22. The control calculator 22 is a work roll bender controller 23, based on a model calculated in advance based on the shape deviation.
Intermediate roll bender controller 24, Intermediate roll shift controller 25
And the control amount is output to the coolant controller 26.

In this configuration, normal shape control is performed by the work roll bender control, the intermediate roll bender control, and the intermediate roll shift control by the controllers 23 to 25. Details of these three controls are omitted because they are well known. At this time, the coolant devices 5A, 5B and the coolant device 6A,
6B supplies a constant amount of coolant flow for cooling the work rolls 2A, 2B or the intermediate rolls 3A, 3B.

In the present invention, the coolant controller 26 controls the coolant flow rate as follows.

FIG. 4 (a) shows changes in the roll crown with respect to the coolant flow rate. As is clear from FIG. 4 (a), the roll crown rapidly increases as the coolant flow rate is reduced. Coolant flow rate is minimum limit value Q _L
In the following cases, a roll seizure phenomenon occurs. On the other hand, as the coolant flow rate is increased, the roll crown becomes almost constant and does not change much. Conventionally, in consideration of control stability, the coolant flow rate at which the roll crown has a substantially constant value is set as the set value. In the present invention, the range of flow rate Q _A ~ Q _B with a large roll crown change is the coolant control range,
The set value Q _s is the median value. The control calculator 22 outputs a control amount to the coolant controller 26 so as to control the coolant flow rate within the coolant control range based on the shape deviation.
Therefore, the coolant controller 26 has a coolant control range.
The coolant flow rate will be controlled within Q _{A to} Q _B.

Further, in the present embodiment, when the coolant flow rate of the set value Q _s is being supplied, for example, when the coolant flow rate should be increased to Q ₁ as shown in FIG. 4B, the maximum coolant in the coolant control range is temporarily set. The flow rate is set to Q _B , and then the target coolant flow rate is set to Q ₁ . That is, the forcing control of the coolant flow rate is performed. On the contrary, when the coolant flow rate is reduced to Q ₂ , the target coolant flow rate Q ₂ is set after setting the minimum coolant flow rate Q _A in the coolant control range.

As described above, the coolant flow rate is controlled. Since the coolant control range is a region in which the roll crown changes greatly with respect to the coolant flow rate, in other words, the influence coefficient is large, the response time constant of the coolant control can be increased. As a result, the accuracy of shape control can be improved.

Further, in the present invention, since the forcing control is applied to the coolant control, the response time constant can be further increased.

FIG. 5 is a characteristic diagram showing a shape range controllable by a work roll bender and an intermediate roll bender. The definition of the horizontal axis crown V ₁ and the vertical axis crown V ₂ is as shown in FIG. As can be seen from FIG. 5, a convex crown,
Although the bender has a large controllability for simple shapes such as a concave crown, it has a limitation for composite shapes such as a W-shaped crown and an M-shaped crown. Now, if the base material crown is C ₁
If it is located at the position W ₁ of the W-shaped crown due to the shape of the roll when it is at the position shown in ( ₁ ), the delivery side shape changes significantly. In this case, it is necessary to roll the roll crown within the controllable range of the bender by changing the roll crown, since it is a condition to roll a good shape while keeping the crown ratio of the inlet side and the outlet side constant. Change from W ₁ to C ₁ by coolant control. When a W-shaped crown is generated, the amount of coolant at the central portion and the edge portion is increased and the quarter portion is decreased. The same applies to the M-type crown, and vice versa.

〔The invention's effect〕

According to the present invention, since the response time of the coolant can be shortened, the accuracy of shape control can be improved. Further, since the control range of the vendor can be used most effectively, good shape control can be performed.

[Brief description of drawings]

FIG. 1 is a composition showing an embodiment of the present invention, FIGS. 2 and 3 are detailed structural diagrams of a main part of a cold rolling mill, and FIG. 4 is a characteristic diagram for explaining the present invention, FIG. , FIG. 6 is a characteristic diagram showing a bending control range. 1 ... Rolling mill, 2 ... Work roll, 3 ... Intermediate roll, 4 ... Backup roll, 5,6 ... Crawler device, 14 ... Shape detector, 21 ... Target shape setter, 22 ...
… Control calculator, 26 …… Coolant controller.

Claims (3)

[Claims] 1. A shape control method for controlling the shape of a material to be rolled by controlling the amount of coolant supplied to a roll of a cold rolling mill, wherein the coolant is in an area where the influence coefficient of the coolant is larger than the allowable minimum amount of coolant. A shape control method for a cold rolling mill, comprising setting a control range and performing coolant control within this coolant control range. 2. The cold rolling mill according to claim 1, wherein, when performing the coolant control, the forcing control is performed so that the maximum coolant flow rate or the minimum coolant flow rate within the coolant control range is obtained. Shape control method. 3. The shape of a cold rolling mill according to claim 1, wherein the cold rolling mill has work rolls and intermediate rolls, and performs work row bender control and intermediate roll bender control. Control method.