JPH05169124A - Speed controller for bar steel rolling mill - Google Patents

Abstract

PURPOSE:To keep a rolling speed of the downstream side normal, and to improve the quality and the yield, even if the end of wire steel passes through a rolling stand of the upstream side and the loop quantity becomes abnormal. CONSTITUTION:When it is detected that the end of bar steel W passes through a rolling stand 1n-1 of the upstream, the loop correction quantity bn detected immediately before passing is still held after the end passes through, and a rolling speed dn of a rolling stand 1n of just the downstream is held in a value immediately before the end passes through. Simultaneously, by holding the cascade compensation quantity en based on the loop correction quantity bn before the end passes through still after the end passes through, influence of a fluctuation of the loop quantity an caused by passing of the end is not exerted on a rolling stand 1n+1 of the downstream side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a speed control device for a strip rolling mill for rolling while adjusting the loop amount of the strip between rolling stands.

[0002]

2. Description of the Related Art One type of conventional rolling equipment has a plurality of rolling stands arranged in series, the loop amount between the rolling stands is detected, and the rolling speed of the rolling stand at the rear portion is corrected. There is so-called downstream control in which a correction amount is sequentially supplied to a rolling stand on the downstream side to perform cascade control. In this equipment, the correction amount obtained from the loop detection value between each rolling stand is sequentially supplied as a cascade amount to the rolling stands further downstream than that, so that more accurate and responsive loop control becomes possible. ..

[0003]

However, in the case of rolling a finite length of steel strip with the above equipment, if the end of the steel strip passes through the rolling stand, the loop between the rolling stands on the downstream side is abnormally lowered. In other words, since the bar steel is relatively thin and bends, it is not stable just by being caught in the rolling stand behind the loop, and the detected value of the loop fluctuates greatly. When the correction amount of the loop based on this detected value is sequentially supplied to the downstream rolling stand as a cascade amount, the rolling speed on the downstream side largely changes due to the influence, which causes deterioration of quality and reduction of yield. There was a problem.

The present invention has been made to solve the above problems, and an object of the present invention is to roll a finite length of steel bar even if the loop amount becomes abnormal due to the passage of its end. An object of the present invention is to provide a speed control device for a strip rolling mill capable of maintaining the downstream rolling speed normally.

[0005]

In order to achieve the above object, the present invention detects the loop amount between rolling stands arranged in series, and rolls the rolling stand immediately downstream from the detected value. In a speed control device for a strip rolling mill that controls the speed and cascade-controls the rolling speed of a rolling stand further downstream, a means for detecting that the end of the strip has passed through the rolling stand, and the end of the strip passes through the rolling stand. And a means for holding the loop correction amount based on the loop amount detected immediately before the end passage, and a means for holding the cascade compensation amount based on the loop correction amount before the end passage even after the end passage. And

[0006]

In the present invention, when it is detected that the end of the steel strip has passed the rolling stand, the loop correction amount detected immediately before passing is retained even after passing the end, and immediately after the value is detected. The rolling speed of the rolling stand is maintained at the value just before passing the end. At the same time, the cascade compensation amount based on the loop correction amount before the end passage is retained even after the end passage, so that the influence of the change in the loop correction amount due to the end passage does not reach the downstream rolling stand.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing the overall configuration of a speed control device for a steel strip rolling mill according to the present invention. In the figure, W is a bar steel,
The rolling stands 1 _n-1 to 1 _{n + 2} arranged at appropriate intervals are sequentially rolled and fed from the left side to the right side in the drawing.

The rolling speed of the rolling stands 1 _n-1 to 1 _{n + 2} is adjusted by a mill rolling motor (not shown) so that the loop amount of the steel strip W formed between the rolling stands is kept proper.
The respective parts between the rolling stands 1 _n-1 to 1 _{n + 2} have substantially the same structure. The operation of the rolling stand 1 _n will be described below.

The loop detector 2 _n is a rolling stand 1 _n-1.
It is installed between the roll stand 1 _n and the rolling stand 1 _n , detects the loop amount a _n of the steel strip W, and sends it to the speed conversion device 3 _n .

[0010] speed converting apparatus 3 _n, the loop correction amount is converted to b _n stand speed command device 4 _n and cascade rate for the loop amount a _n, for correcting the feed rate of the rolling stand 1 _n representing the height Send to controller 5 _n . The speed converter 3 _n, after the end of the long products W passes through the roll stand 1 _n-2 of the upstream (not shown), time to pass through the roll stand 1 _n, the loop amount a _n input immediately before Is maintained, the loop correction amount b _n converted from that value is continuously output, and after the end passes through the rolling stand 1 _n , the held value is cleared and the next bar W is sent. Wait for you to come.

The cascade speed control device 5 _n calculates the sum of the loop correction amount b _n and the cascade compensation amount f _n-1 and sends it as a new cascade compensation amount e _n to the cascade command holding device 6 _n, and also from the upstream. Using the cascade compensation amount f _n-1 as the cascade compensation amount c _n , the stand speed command device 4 _n
Send to.

The stand speed command device 4 _n calculates the sum of the loop correction amount b _n and the cascade compensation amount c _n to obtain the speed command d.
_{As n,} it is sent to the rolling stand 1 _n . Rolling stand 1
_{For n} , the speed of a mill rolling motor (not shown) is adjusted by a speed command d _n to keep the loop amount a _n of the steel strip W at a predetermined value.

The cascade command holding device 6 _n normally passes the inputted cascade compensation amount e _n as it is to obtain a cascade compensation amount f _n, and sends it to the downstream cascade speed control device 5 _{n + 1} . In addition, the cascade command holding device 6
_n continues to output while holding the cascade compensation amount e _n input immediately before _n until the end of the steel strip W passes through the rolling stand 1 _n-1 and passes through the rolling stand 1 _{n + 1} .

The same applies to the other rolling stands 1 _{n + 1} and 1 _{n + 2} . With these configurations, when the ends of the steel strip W pass through the rolling stands 1 _n-1 to 1 _{n + 2} in order, the loop level between the rolling stands immediately before and immediately after the passing greatly decreases, and the detected loop amount. a _n but becomes abnormal, holds the normal loop amount a _n before the abnormal value is detected, the speed control of the rolling stand 1 _n based on the abnormal value is prevented performed. At the same time, the cascade compensation amount e _n also retains the normal value before that, and the abnormal loop amount a _n
The influence of is not trying to reach the downstream.

Table 1 shows specific operation timings of each speed conversion device 3 and each cascade command holding device 6.

[0016]

[Table 1]

The "ST missing" in the upper column of Table 1 indicates immediately after the steel strip W has passed through each rolling stand. "ST
"Before pulling out" refers to a period after the steel strip W has passed through each rolling stand and before passing through the next rolling stand.

In the speed converter column, "hold" indicates that the output value is being held, "control off" indicates that the output value is being cleared, and "control" indicates that normal operation is in progress. .. Further, in the column of the cascade command holding device, “through” indicates a state in which the input value is output as it is, and “hold” indicates a state in which the output value is held. In addition, after the bar W has passed, the operation of each part is restored as shown in Table 1 to enter the standby state.

When the end of the steel strip W passes through the rolling stand in this manner, the adverse effect on the downstream rolling stand that has occurred in the speed control device of the conventional steel strip rolling mill is eliminated. The passage of the end of the steel strip W in the embodiment is detected from the change in the loop amount a detected by each loop detection device 2 and the change in the current value of the mill rolling motor that drives the rolling stand 1.

[0020]

As described above, according to the present invention, when the end of the steel strip passes through the rolling stand, the loop correction amount detected immediately before the passage is retained,
The abnormality of the loop compensation amount due to the passing of the end of the rolling stand cannot be transmitted to the rolling stand on the downstream side. As a result, even if the end of the steel strip passes through each of the rolling stands in sequence, the rolling speed of the rolling stand on the downstream side can be normally maintained, and the accuracy and yield of the finished steel strip can be prevented from lowering.

[Brief description of drawings]

FIG. 1 is a diagram showing an overall configuration of an embodiment of the present invention.

[Explanation of symbols]

1 _n-1 to 1 _{n + 2} rolling stand 2 _n to 2 _{n + 2} loop detection device 3 _{n to} 3 _{n + 2} speed conversion device 4 _n to 4 _{n + 2} stand speed command device 5 _{n-1 to} 5 _{n + 2} Cascade speed control device 6 _{n-1 to} 6 _{n + 1} Cascade command holding device W bar steel

Claims (1)

[Claims] 1. A loop amount between rolling stands arranged in series is detected, the rolling speed of a rolling stand immediately downstream is controlled by the detected value, and the rolling speed of a rolling stand further downstream is cascade controlled. In the speed control device of the strip rolling mill, the means for detecting that the end of the strip has passed the rolling stand, and the end of the loop correction amount based on the amount of loop detected immediately before the end of the strip has passed the rolling stand. A speed control device for a steel strip rolling mill, comprising: a means for holding afterward, and a means for holding the cascade compensation amount based on the loop correction amount before passing through the end even after passing through the end.