JPH0687012A - Speed controller for continuous rolling mill - Google Patents

Abstract

PURPOSE:To improve the dimensional accuracy in the tip part of a rolled stock by controlling the speed of each rolling mill in terms of feedforward when rolling is started. CONSTITUTION:In a speed controller for a continuous rolling mill, a correcting device 8 with which an initial set speed of each rolling mill 1 on the downstream side from a 2nd rolling mill 1 is corrected by DELTAVi+1=alpha.{(1+Fi)/(1-Gi+1)}.DELTAV1 based on a difference DELTAL between the detected amount of loop by a loop detecting means 7 and the objective amount of loop when rolling is started is connected to each driving device 2. Where, DELTAV2={1/(1- G2)}.DELTAL/DELTAT, subscript: the number of rolling mill and i>=2, Fi: the forward slip of steel sheet at a i-th rolling mill, Gi+1: the backward slip at a (i+1)th rolling mill, DELTAT: loop detecting time, alpha: correction factor.

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 continuous rolling mill.

[0002]

2. Description of the Related Art In a continuous rolling mill, as shown in FIG. 2, a plurality of rolling mills 20 are arranged in series, and each rolling mill 20 is synchronously driven by an independent drive unit 21. Loop detection means 23 of the rolled material 22 is provided between the rolling mill 20 on the upstream side and the rolling mill 20 on the downstream side in the row, based on the difference between the loop detection amount by the loop detection means 23 and the target loop amount. The speed of the rolling mill 20 upstream of the detection means 23 is corrected by the controller 24, and feedback control is performed so that the loop amount approaches the target value.

This feedback control has been uncontrolled for several hundred milliseconds after the start of rolling until the rolling is stabilized.

[0004]

In the above-mentioned conventional feedback control device, the control is in the uncontrolled state for several hundreds of milliseconds at the start of rolling, and in the feedback control for controlling the speed on the upstream side of the detection unit. When the leading edge of the rolled material (steel sheet) passes through the downstream rolling mill, the speed of the downstream rolling mill cannot be controlled. It depends on the hit rate of the set speed of the main engine.

However, when the temperature change of the rolled material or the prediction model includes an error, there is a problem with the set value, and there is a problem that the target dimensional accuracy cannot be obtained. Therefore, an object of the present invention is to provide a speed control device for a continuous rolling mill in which the speed of each rolling mill is feedforwardly controlled at the start of rolling to improve the dimensional accuracy of the rolled material tip. And

[0006]

In order to achieve the above object, the present invention takes the following means. That is, the feature of the present invention is that a plurality of rolling mills are arranged in series, and each rolling mill is synchronously driven by an independent driving device,
A loop detecting means for rolled material is provided between the upstream first rolling mill and the downstream second rolling mill in the rolling mill train, and at the start of rolling, the loop detection amount and the target loop by the loop detecting means. Based on the difference ΔL with the amount, the initial set speed of each rolling mill downstream of the second rolling mill is

[0007]

ΔV _{i + 1} = α · {(1 + F _i ) / (1-G _{i + 1} )} · ΔV _i where ΔV ₂ = {1 / (1-G ₂ )} · ΔL / ΔT subscript i Indicates the rolling mill number, i ≧ 2 F _i is the steel plate advance rate of the i-th rolling mill G _{i + 1} , the backward movement rate of the (i + 1) -th rolling mill ΔT, the loop detection time α is the correction A correction device that performs speed correction by a coefficient is connected to each of the driving devices.

[0008]

According to the present invention, after the start of rolling, the loop detection means detects the loop amount of the rolled material immediately after the leading end of the rolled material passes through the first rolling mill and enters the second rolling mill. Then, the difference ΔL between the target loop amount L ₀ and the detected loop amount L
Is calculated as ΔL = L−L ₀ (1)

Further, the time ΔT from when the leading end of the rolled material enters the second rolling mill until the error in the loop amount reaches the above ΔL is counted. That is, it means that an error of the loop amount of ΔL occurs within ΔT minutes immediately after the leading end of the rolled material enters the second rolling mill. This loop amount error ΔL is
This was caused by the improper initial setting speed of the second rolling mill. Since this initial setting value is set according to the prediction model, the initial setting speeds of the downstream rolling mills after the second rolling mill should be inappropriate.

Therefore, it is necessary to correct the initial value of the rolling mill on the downstream side. However, since the speed of each rolling mill is not constant and is higher toward the downstream side, the initial values of the rolling mills on the downstream side are all uniformly the same amount in accordance with the generation ratio of the loop amount error ΔL. Even if it corrects, it does not become a highly accurate correction. That is, different corrections must be made for each rolling mill.

Therefore, in the present invention, the initial setting speed of each rolling mill is set to

[0012]

[Formula 3] ΔV _{i + 1} = α · {(1 + F _i ) / (1-G _{i + 1} )} · ΔV _i ...... (2) where ΔV ₂ = {1 / (1-G ₂ )} ・Correction is made based on ΔL / ΔT i ≧ 2.

Now, the grounds for introducing the correction formula will be described. Generally, when the speed V _{m of} the rolling mill, the incoming speed V _{in of} the rolled material, the outgoing speed V _out of the rolled material, the advance rate F, and the reverse rate G are given,

[0014]

(4) V _in = (1-G) V _m ...... (3) V _out = (1 + F) V _m ...... (4) is established. Further, since the outlet speed V _out of the upstream rolling mill and the inlet speed V _in of the downstream thereof are equal to each other, generally, the velocity of the i-th rolling mill is V _i and its advance rate is F _i, and its downstream side is Assuming that the speed of the (i + 1) -th rolling mill of the above is V _{i + 1} and the reverse rate is G _{i + 1} , the following formulas (3) and (4) can be used as a general formula.

[0015]

[Formula 5] V _{i + 1} = {(1 + F _i ) / (1-G _{i + 1} )} · V _i (5) holds. The speed error ΔV is added to the speed V _i of the i-th rolling mill.
If there is _i , this error is for the (i + 1) th rolling mill.

[0016]

## EQU6 _## A velocity error of {(1 + F _i ) / (1-G _{i + 1} )} ΔV _i (6) is given. That is, as a general formula

[0017]

[Formula 7] ΔV _{i + 1} = {(1 + F _i ) / (1-G _{i + 1} )} · ΔV _i (7) holds. On the other hand, between the first rolling mill and the second rolling mill, the loop amount error ΔL is caused by
This is because the speed V ₂ of the second rolling mill has a speed error of ΔV ₂ . Therefore,

[0018]

(8) (1-G ₂ ) · ΔV ₂ · ΔT = ΔL (8) holds. Therefore, for ΔV ₂ ,

[0019]

[Formula 9] ΔV ₂ = {1 / (1-G ₂ )} · ΔL / ΔT (9) holds. In the third rolling mill, from the above general formula

[0020]

[Formula 10] ΔV ₃ = {(1 + F ₂ ) / (1-G ₃ )} · ΔV ₂ (10) holds, and when the formula (9) is substituted into the formula (10),

[0021]

[Expression 11] ΔV ₃ = {(1 + F ₂ ) / (1-G ₃ )} · {1 / (1-G ₂ )} · ΔL / ΔT (11) Therefore, as a general formula

[0022]

[Formula 12] ΔV _{i + 1} = α · {(1 + F _i ) / (1-G _{i + 1} )} · ΔV _i …… (2) where ΔV ₂ = {1 / (1-G ₂ )} ・A correction coefficient is established for ΔL / ΔT i ≧ 2 α.

As described above, since the speed error of the rolling mill on the upstream side is propagated to the downstream side via the advance rate and the reverse rate,
By correcting the initial set speed of each rolling mill using this relationship, the initial speed of each rolling mill is correctly corrected. That is, since the initial setting speed of each rolling mill is set according to a certain prediction model, an independent error does not occur for each rolling mill but a constant deviation rate from the prediction model. There is a correlation between machine-to-machine errors. Therefore, by measuring the error in the second rolling mill, the error in the rolling mill downstream thereof can be predicted by the equation (2). That is, it is understood that the speed of each rolling mill should be corrected by the above equation (2).

[0024]

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, a plurality of rolling mills 1 are arranged in series, and each rolling mill 1 has a driving device 2 including an independent motor.
Driven synchronously by. A speed setting device 3 is connected to each drive device 2. Each speed setting device 3 is connected to the controller 4. The data setting device 5 is connected to the controller 4.

A loop detecting means 7 for detecting the loop amount of the rolled material 6 is provided between the first rolling mill 1 on the upstream side and the second rolling mill 1 on the downstream side in the rolling mill train. This detecting means 7 is connected to the speed correction device 8 and the speed correction device 8
Is connected to the controller 4 and the data setting device 5. In the data setting device 5, the initial set speed V _i of each rolling mill 1 and the advanced rate F of the rolled material 6 in each rolling mill 1 are set.
Various data such as _i , the reverse rate G _i , and the target loop amount L ₀ are input in advance. The initial speed V _i of each rolling mill 1 is output to each speed setting device 3 via the controller 4 by the data of the data setting device 5. Incidentally, FIG.
In FIG. 1, the driving device and the speed setting device for the first and second rolling mills 1 are omitted in the drawing, but the initial speed is similarly set for these rolling mills 1.

After the start of rolling, the tip of the rolled material 6 is the first rolling mill.
Immediately after passing through 1 and entering the second rolling mill 1, the loop amount of the rolled material 6 is detected by the loop detection means 7. Then, the difference ΔL between the target loop amount L _o and the detected loop amount L is obtained by the correction device 8 as ΔL = L−L ₀ (1).

Further, the time ΔT from when the leading edge of the rolled material enters the second rolling mill until the error in the loop amount reaches the above ΔL is counted. Then, in the correction device 8, based on the loop amount difference ΔL, the correction value of the initial set speed of each rolling mill on the downstream side of the second rolling mill is calculated according to the following equation.

[0028]

[Expression 13] ΔV _{i + 1} = α · {(1 + F _i ) / (1-G _{i + 1} )} · ΔV _i …… (2) where ΔV ₂ = {1 / (1-G ₂ )} ・ΔL / ΔT The subscript i indicates the rolling mill number, i ≧ 2 F _i is the steel plate advance rate of the i-th rolling mill G _{i + 1} is the backward travel rate of the (i + 1) th rolling mill ΔT is the loop detection For the time α, a correction coefficient, and the correction value is output to the speed setting device 3 via the controller 4, and the initial setting speed of each rolling mill 1 is corrected by the correction value.

Therefore, at the start of rolling, when the leading edge of the rolled material 6 passes through each rolling mill 1 on the downstream side of the second rolling mill 1 and thereafter, the initial set speed of each rolling mill 1 is It is driven at the speed corrected by the value. As a result of performing the feed forward control according to the embodiment of the present invention, the control accuracy of the strip width and strip thickness at the most distal end of the rolled material was improved.

Table 1 shows the amount of improvement in the control accuracy of the present invention as compared with the conventional method. The conventional method referred to here is a method in which control is not performed for several hundreds of milliseconds at the start of rolling.

[0031]

[Table 1]

The present invention is not limited to the above embodiment.

[0033]

According to the present invention, in the continuous rolling mill, the strip width and strip thickness accuracy at the most advanced portion of the rolled material at the start of rolling are improved.

[Brief description of drawings]

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

FIG. 2 is an explanatory diagram showing conventional control.

[Explanation of symbols]

 1 rolling mill 2 drive device 7 loop detection means 8 correction device

Claims (1)

[Claims] 1. A plurality of rolling mills are arranged in series, and each rolling mill is synchronously driven by an independent driving device,
Loop detection means for rolled material is provided between the first rolling mill on the upstream side and the second rolling mill on the downstream side in the rolling mill train, and at the start of rolling, the loop detection amount and the target loop by the loop detecting means. Based on the difference ΔL from the amount, the initial set speed of each rolling mill downstream of the second rolling mill is expressed as follows: ΔV _{i + 1} = α · {(1 + F _i ) / (1-G _{i + 1} )} · ΔV _i where ΔV ₂ = {1 / (1-G ₂ )} · ΔL / ΔT The subscript i indicates the rolling mill number, and i ≧ 2 F _i is the steel plate advance rate of the i-th rolling mill. G _{i + 1} is a reverse ratio ΔT of the (i + 1) th rolling mill, a loop detection time α is a correction coefficient, and a correction device for performing speed correction by a correction coefficient is connected to each of the driving devices. Speed controller for continuous rolling mill.