JPH04356309A - Method for controlling load balance of plural lines of rolling mill - Google Patents

Abstract

PURPOSE:To stabilize rolling and to prevent the generation of flaws and end reduction by continuously detecting load after biting a material, calculating the load factor at each stand, selecting a corrected stand in accordance with the difference between the reference value and an actual value and correcting the target value of thickness control. CONSTITUTION:In the control of load balance of a tandem rolling mill provided with a measuring device with which the load and thickness of rolled stock are measured and draft controller with which the thickness of rolled stock is controlled at the target value, the load after biting the material is dynamically detected and the load factor at each stand is calculated as the load at each stand/the total load. According to the large or small ratio of the total sum at all stand of the difference between the reference value and the actual value of the load factor at each stand, the corrected stand is selected and the target value of thickness control is corrected.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to balance control for keeping the rolling load of each roll stand of a tandem rolling mill within an appropriate distribution ratio range.

0002

[Prior Art] As load balance control for a tandem rolling mill, Japanese Patent Publication No. 2-39326 and Japanese Patent Publication No. 2-3932
As disclosed in Publication No. 7, a method focuses on the relative change (ΔPi/Pio) in the rolling force of each stand from the initial standard value and corrects the gap between each stand so as to satisfy a predetermined ratio. There is.

[0003] With this method, even if the rolling load amount does not match the rolling model due to measurement errors or rolling disturbances, it can be made to match the set ratio in a short time without impairing the accuracy of the product thickness. There is an advantage.

0004

[Problems to be Solved by the Invention] However, in the case of this method, if there is a large deviation in the initial setting conditions, it is not possible to arbitrarily change the standard load distribution during rolling, and the difference between each stand is If there is too much, there is a drawback that the amount of gap correction varies greatly between stands, causing rolling troubles. In addition, there is a risk that the load on the stand will increase due to the imbalance of the load, which may cause scratches, and if the load increases on the subsequent stand during sheet removal, it will cause tailing and reduce the work rate.

The problem to be solved by the present invention is to solve the problem of load balance in the conventional tandem rolling mill mentioned above, and to be able to control even when the initial setting error is large, and to set the standard at any time during rolling. The present invention provides a load balance control method that can change the load distribution and also optimize the amount of correction between each stand by selecting the number of correction stands depending on whether the error is large or small.

[0006]

[Means for Solving the Problems] The present invention provides a load balancer for a multi-row rolling mill having a measuring device for measuring the load and thickness of a material to be rolled, and a reduction control device for controlling the thickness of the material to be rolled to a target value. In the control, the load after the material is bitten is dynamically detected, the load factor of each stand is calculated as each stand load/total load, and the difference between the reference value and actual value of the load factor of each stand is calculated as the sum of all stands. The present invention is characterized in that the target value for plate thickness control is corrected by selecting a correction stand depending on the magnitude of the ratio.

[0007]

[Operation] The present invention performs control based on the total load ΣPn of the tandem rolling mill, and is not based on the load distribution that includes an error set in the initial setting. Since this method is given as a standard,
It is possible to control even when the initial setting error is large, and the standard load distribution can be changed arbitrarily during rolling.Moreover, by selecting the number of correction stands depending on the size of the error, the amount of correction between each stand can be adjusted. can be optimized.

[0008]

[Example] Figure 1 shows a system for controlling the load balance in a tandem rolling mill equipped with a measuring device for measuring the load and thickness of the material to be rolled and a rolling control device for controlling the thickness of the material to be rolled. It is an explanatory diagram.

In the figure, reference numeral 1 indicates a load cell installed in each rolling stand 2. As shown in FIG. Reference numeral 3 denotes a plate thickness control device (AGC) installed individually in each stand, which performs roll gap control to match the plate thickness target 4 set in advance. 5 indicates a load factor calculation device, and 6 indicates a preset load balance reference value. 7 is a load balance error tolerance determination device, 8 is a stand selection device, and 9 is a plate pressure target value correction device.

In this control system, load balance control is performed in the following manner.

A preset plate thickness target 4 is input to the plate thickness control device 3, and is also input to the load factor calculation device 5.

The load cell 1 detects changes in the load after the material to be rolled enters the rolling mill over time, and the detected load data is input to the plate thickness control device 3 to adjust the plate thickness to a preset value. Perform roll gap control to match target 4. The feature of the present invention is that when such roll gap control is input into the load factor calculation device 5 and compared with a load balance reference value 6 inputted in advance, it is performed based on the ratio Pi/ΣP of each stand load Pi and the total load ΣP. At the point.

That is, the load data detected by the load cell 1 is also input to the load factor calculation device 5, where the ratio Pi/Σ of each stand load Pi to the total load ΣP is calculated.
P is calculated and compared with the load balance reference value 6 inputted in advance.

The compared load balance error, Pai (load balance reference value) - Pi/ΣP, is determined by the load balance error tolerance determining device 7 to determine whether or not it is within tolerance, and a reduction correction stand is selected. In the case of the example shown in FIG. 2, the plate thickness target value of the most upstream stand, F2 stand, which is out of the allowable value in FIG. 2(a), is first changed. In this case, since it is smaller than the target load factor, a command to reduce the target plate thickness on the exit side of the F2 stand is output from the plate thickness target value correction device 9, and the F2
Performs control to keep the load factor of the stand within the allowable value. As a result, the load factor of the F2 stand falls within the allowable value, and the load factors of the F3 to F6 stands change accordingly, as shown in the figure (
As shown in b), in this case the load factor of the F3 stand was originally within the permissible value, but now it is closer to the target value. However, the load factor of the F4 stand will be further out of the allowable range, so next time we will focus on the load factor of the F4 stand and reduce the target thickness of the F4 stand.
Increase the load factor of the stand to bring it within the allowable range. F4
Since the load factor of the stands was increased, as shown in FIG. 2(c), the load factor of the F5 and F6 stands was decreased as a result, and the overall load was balanced. In this way, the plate thickness target value is selectively corrected by the plate thickness target value correction device 9 starting from the most upstream stand where the load factor is outside the allowable range, and when the load factor is within the allowable range, the next stand is started. By making selections and making similar modifications, the overall load can be balanced.

[0015]

[Effects of the Invention] The following effects can be achieved by the present invention.

(1) Compared to the conventional method in which control is performed only by changing the initial setting model, it is possible to control the loads of all stands in a well-balanced manner, and it is possible to dynamically change the load balance.

(2) Therefore, no flaws will occur due to unbalanced loads on the stands, and strong compressive force will not be applied to the subsequent stands, effectively preventing the occurrence of the so-called bottom-slip phenomenon. becomes possible.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a control system as an embodiment of the present invention, which is equipped with a measuring device that measures the load and thickness of a material to be rolled, and a reduction control device that controls the thickness of the material to be rolled. An example of application to a tandem rolling mill is shown.

FIG. 2 shows changes in load balance errors at each stand to explain the control method of the present invention.

[Explanation of symbols]

1 Load cell 2 Rolling stand 3 Plate thickness control device (AGC) 4 Plate thickness target 5 Load factor calculation device 6 Load balance reference value 7 Load balance error tolerance judgment device 8 Stand selection device 9 Plate thickness target value correction device

Claims (1)

[Claims] Claim 1: In load balance control of a tandem rolling mill, which has a measuring device that measures the load and thickness of the material to be rolled, and a reduction control device that controls the thickness of the material to be rolled to a target value, after the material is bitten. Dynamically detects the load of each stand, calculates the load factor of each stand as each stand load/total load, and selects a corrected stand based on the ratio of the difference between the standard value and actual value of the load factor of each stand to the sum of all stands. A load balance control method for a multi-row rolling mill that corrects the target value for plate thickness control.