JP2501490B2 - Plate thickness controller for tandem rolling mill - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a controller for a tandem rolling mill, and more particularly to an automatic plate thickness controller for rolling a material to be rolled in a rolling mill for rolling metal strip such as a tandem cold rolling mill.

[0002]

2. Description of the Related Art Conventionally, a plate speed value of a plate speed meter, which is a speed detecting means for detecting a strip speed provided between stands, and a plate thickness value of one or more plate thickness gauges on a front side or a rear side are used. The so-called mass flow AGC (Automatic Gauge Control) that controls the speed of the stand roll so that the intermediate stand plate thickness becomes the target plate thickness by the mass flow method is used immediately after passing the plate, passing through the welding point, immediately after changing the running plate thickness, etc. Even if the control is started and the gain always operates with the same gain, and the roll slip, that is, the advance rate becomes a large negative value, or the plate speed meter malfunctions and the abnormal advance rate occurs, the control operation is restricted. There wasn't.

[0003]

However, in the conventional mass flow AGC, the following problems (1), (2),
There are (3) and (4).

(1) At the start of control of the mass flow AGC immediately after passing the plate, after passing the welding point, immediately after changing the plate thickness during running, disturbances such as mill setup error, deviation and fluctuation of original plate thickness, and manual intervention of the operator occur most. In some cases, this disturbance and the mass flow AGC operation produce a synergistic effect, causing troubles such as plate thickness variation, excessive tension between stands, and insufficient tension.

(2) During steady rolling after the completion of acceleration of the rolling mill, the original plate thickness is stable, and the final finished plate thickness is secured and stable by the operation of various AGCs. Further, in the high-speed rolling state, the rolling oil is entrained in the roll bite more than at the low speed, and the work roll is more likely to slip (the advance rate is negative) than at the low speed. In such a state, mass flow AG
Although C is not required so much, there is a case where the mass flow AGC operation becomes a disturbance of the final finished plate thickness during steady rolling or a roll slip is promoted by the mass flow AGC operation when the gain is always the same as in the conventional case. Excessive roll slip will cause flaws in the strip.

On the other hand, in the case of a continuous rolling mill in which a pickling facility, a welding machine, etc. are directly connected to the entrance side of the rolling mill, there are cases where the rolling mill speed is reduced to an extremely low speed due to the connected front process side. During this acceleration / deceleration, the uniform speed of each stand mill motor and the coefficient of friction of each stand change abruptly, so the plate thickness between stands tends to fluctuate. At this time, the gain of the mass flow AGC is made large and the plate thickness is sufficient. There is a need to secure it.

(3) Excessive roll slip as described above leads to flaws in the strip to be rolled. When the tonnage of work rolls increases, the roll slip may increase even during low-speed rolling. In this case, in the conventional technique, the mass flow AGC was not automatically turned off.

(4) The mass flow AGC performs the original control only when the inter-stand plate speed meter operates normally. However, when the plate speed meter gives an abnormal value, the mass flow A is detected by the conventional technique.
The GC is operating abnormally, causing problems such as excessive or insufficient tension between stands.

An object of the present invention is to provide a tandem rolling mill which enables stable control at the start of control of the mass flow AGC and prevents slipping between a work roll of a stand and a strip. It is to provide a plate thickness control device.

[0010]

DISCLOSURE OF THE INVENTION The present invention is directed to a strip thickness detecting means for detecting a strip strip thickness h0 on the inlet side or the outlet side of a tandem rolling mill and a strip speed at the same place as the strip thickness detecting means of the tandem rolling mill. first speed detecting means for detecting v0,
The plate thickness hm is responsive to the outputs of the second speed detecting means for detecting the speed vi on the exit side of each of the stands of the tandem rolling mill, the plate thickness detecting means, and the first and second speed detecting means.
i,

[0011]

## EQU1 ## hmi = (v0.h0) / vi is calculated, and the difference Δhi (= h from the predetermined target plate thickness h0i
mi-h0i) calculating means, a motor for driving the work roll of each stand, and the thickness difference Δhi.
A means for controlling the speed of the motor so as to be zero, and a gain changing means for changing the gain of the control means so as to increase with the passage of time from the start of control to bring it to a predetermined constant value. It is a strip thickness control device for a tandem rolling mill characterized by including the above.

Further, according to the present invention, the strip thickness detecting means for detecting the strip thickness h0 on the inlet side or the outlet side of the tandem rolling mill and the strip speed v0 at the same place as the strip thickness detecting means of the tandem rolling mill are detected. In response to the outputs of the first speed detecting means, the second speed detecting means for detecting the exit side speeds vi of the plurality of stands of the tandem rolling mill, the plate thickness detecting means, and the first and second speed detecting means. And the plate thickness hmi,

[0013]

## EQU00002 ## hmi = (v0.h0) / vi is calculated, and a difference .DELTA.hi (= h from the predetermined target plate thickness h0i
mi-h0i) calculating means, a motor for driving the work roll of each stand, and the thickness difference Δhi.
And a gain changing means for changing the gain of the control means such that the gain of the control means decreases so as to decrease when the speed vi detected by the second speed detecting means increases. Is a plate thickness control device for a tandem rolling mill.

Further, according to the present invention, the strip thickness detecting means for detecting the strip thickness h0 on the inlet side or the outlet side of the dandem rolling mill and the first velocity for detecting the strip velocity v0 at the same place as the strip thickness detecting means of the stand. In response to the outputs of the detection means, the second speed detection means for detecting the speed vi on the exit side of each of the plurality of stands of the tandem rolling mill, the plate thickness detection means, and the first and second speed detection means, Plate thickness hmi,

[0015]

[Mathematical formula-see original document] hmi = (v0 · h0) / vi is calculated, and a difference Δhi (= h from the predetermined target plate thickness h0i
mi-h0i) calculating means, a motor for driving the work roll of each stand, and the thickness difference Δhi.
In response to the outputs of the means for controlling the speed of the motor so that zero becomes zero, the work roll speed detecting means for detecting the speed vRi of the work roll of the stand, and the second speed detecting means and the work roll speed detecting means. , Advanced rate A,

[0016]

## EQU00004 ## A = (vi-vRi) / vRi is calculated, and the advance rate A is negative,
And a means for holding the gain of the control means at a predetermined value when the absolute value exceeds a predetermined value.

[0017]

In the mass flow AGC of the present invention, the strip plate thickness h0 on the inlet side of the rolling mill and the strip speed v0 on the inlet side thereof.
And the product v0 · h0 is constant, that is, the product is constant on the inlet side and the outlet side of each of the plurality of stands provided in the tandem rolling mill, and the predetermined target plate thickness h0i on the outlet side of each stand is , Plate thickness h calculated
The speed of the motor is controlled by the control means so that the difference Δhi (= hmi−h0i) from mi is zero. According to the present invention, at the start of control, that is, immediately after passing the plate, when passing the welding point of a plurality of roll-shaped strips, and when passing the running plate thickness change point, etc., the gain of the control means is increased with time. And finally bring it to a predetermined constant value. The fact that the gain is changed with the passage of time may be accompanied by the passage of actual time, or may be accompanied by an increase in the rolling distance, or may be accompanied by other factors, or substantially. In addition, it suffices to be able to cope with the passage of time from the start of control. In order to change the gain of the control means, the coefficient Ci1 that gradually increases with the passage of time may be multiplied. As a result, disturbances (mill setup error, deviation and fluctuation of original plate thickness, manual intervention of the operator, etc.) that occur at the same time when mass flow AGC starts and plate thickness fluctuation due to the synergistic effect of mass flow AGC, excessive tension and insufficient tension between stands are prevented. be able to.

Further, according to the present invention, when the exit-side speed vi of each stand detected by the second speed detecting means increases, the gain of the control means is changed so as to decrease. Therefore, the present invention can be realized by, for example, a configuration in which the gain of the control means is multiplied by a coefficient Ci2 that is small when the strip speed is high and that changes greatly when the strip speed is low. With such a configuration, the gain is reduced in a region where the mass flow AGC does not have to be so large at the time of high speed, an excessive operation of the mass flow AGC such as work roll slip is prevented, and the mass flow A in the low speed region is reduced.
In a region where the GC gain is desired to be increased, the gain can be increased and a predetermined plate thickness accuracy can be secured.

Further in accordance with the present invention, mass flow AGC
When the advance rate calculated with the same plate speed meter and work roll peripheral speed used in the mass flow AGC becomes a certain value or less during the operation of, the operation output is held, and it occurs even at low speed. When the work roll slips,
The abnormal output of the plate speed meter itself is automatically judged and the mass flow A
It is possible to prevent variation in plate thickness due to GC, and excessive or insufficient tension between stands.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an overall system diagram of an embodiment of the present invention. The strip 1 which is a steel strip to be rolled is rolled by passing through a plurality of (4 in this embodiment) stands ST1 to ST4 in this order. The strip thickness h0 on the entry side of such a tandem rolling mill is detected by the strip thickness detection means 2, and the strip speed v0 on the entry side of the tandem rolling mill is detected by the speed detection means 3. Between the stands ST1 to ST4, the speed detecting means 4,
5 and 6 are provided to detect the strip speeds v1, v2 and v3, and a speed detecting means 7 is provided at the exit side of the stand ST4 at the final stage to detect the strip speed v4. Control circuits 8, 9, 1 for each of the stands ST1 to ST4
0 and 11 are provided respectively, and these control circuits 8 and
9, 10, 11 are connected to a processing circuit 12 realized by a microcomputer or the like. Plate thickness detection means 2
The outputs of the speed detecting means 3 to 7 are supplied to the processing circuit 12. In the processing circuit 12, for example, the stand ST
In relation to the control circuit 10 relating to No. 3, according to the mass flow equation (1), the stand S
The plate thickness hmi on the output side of Ti is calculated and obtained.

[0021]

[Formula 5] v0 · h0 = vi · hmi

[0022]

[Equation 6]

A signal representing the plate thickness hmi obtained by this calculation is derived from the line 13 and given to the subtraction circuit 14. A signal representing a predetermined target plate thickness h0i is given to the subtraction circuit 14 from the target value setting circuit 15. Subtraction circuit 14 derives on line 16 a signal representing the difference Δhi.

[0024]

[Delta] hi = hmi-h0i The control means 17 performs the operation shown in the equation 4 and the line 1
A signal for controlling the speed of the motor 36 is led to the line 19 so that the difference Δh via 6 becomes zero.

[0025]

[Equation 8]

Here, the gain or transfer function of the control means 17 is G, k1 and k2 are constants, and s is a plus operator. In this way, the control means 17 performs proportional and integral control of the speed of the motor 18.

FIG. 2 is a block diagram showing a concrete configuration of the control means 17. The signal from the line 16 is given to the proportional arithmetic circuit 20 and the integral arithmetic circuit 21, respectively,
The outputs of these circuits 20 and 21 are given to the adder 22 and are derived from the line 19.

The output from the control means 17 is applied via line 19 to a multiplier 24. The multiplier 24 multiplies the gain G of the control means 17 by the coefficient C3 to calculate C3 · G, and derives the output on the line 25.

The coefficient C3 in the multiplier 24 is changed by the arithmetic circuit 26. The arithmetic circuit 26 outputs the output from the seam detecting means 27 provided on the inlet side of the tandem rolling mill and the work roll 28 of the stand ST4 at the final stage.
In response to the output of the speed detecting means 29 for detecting the peripheral speed vR4. The distance L3 between the seam detection means 27 and the work roll 30 of the stand ST3 is known, so after the seam detection means 27 has detected the welded seam of the strip 1, the time at which the seam reaches the stand ST3. Can be calculated by the output of the speed detecting means 29. As a result, the arithmetic circuit 26 sets the coefficient C31 as shown in FIG. 3 from the start of control at time t1 when the joint of the strip 1 reaches the stand ST3,
Increase over time. At time t2, the coefficient C3
1 becomes a constant value of 1.0. As another embodiment of the present invention, the traveling distance of the strip 1, that is, the rolling distance may be used instead of the passage of time in FIG.

The arithmetic circuit 26 responds to the speed vR4 of the work roll 28 of the final stand ST4 detected by the speed detecting means 29 and changes the signal representing the coefficient C32 corresponding to the speed vR4 as shown in FIG. Ask for. The signal representing the coefficient C3 derived from the line 32 by this is the product of the coefficients C31 and C32.

[0031]

## EQU00009 ## C3 = C31.C32 As another embodiment of the present invention, instead of detecting the speed of the work roll 28 of the stand ST4 at the final stage by the speed detecting means 29, each work roll of the other stands ST1 to ST3. The coefficient Ci2 may be changed as shown in FIG. 4 based on the speed of.

As described above, the coefficient C31 is changed so as to increase with the lapse of time from the start of the control so as to bring it to a predetermined constant value. It is possible to prevent the occurrence of troubles such as. By changing the coefficient C32 according to the work roll speed vR4 as shown in FIG. 4, slip between the strip 1 and the work rolls 28, 30 can be prevented, and rolling can be performed with a stable plate thickness. .

The output from line 25 is applied to holding circuit 33. The holding circuit 33 includes a speed detection circuit 34.
The peripheral speed vR3 of the work roll 30 detected by is detected and given, and the speed of the strip 1 is detected and given by the speed detecting means 6. Holding circuit 33
Is calculated by calculating the advanced rate A.

[0034]

[Equation 10]

This holding circuit 33 represents the gain C3.G from the line 25 at the time when the advance rate A is negative and the absolute value becomes equal to or larger than a predetermined value, when the absolute value becomes the predetermined value. Keep constant to the value. This holding circuit 33
Outputs the output of the line 25 to the line 35 as it is, except when the advanced rate A is negative as described above and the absolute value thereof is equal to or larger than a predetermined value. The output from the line 35 is given to the drive circuit 37. This drive circuit 37
Drives a motor 36, which causes the work roll 30 to
Is driven to rotate. In this way, by the action of the holding circuit 33, the slip between the strip 1 and the work roll 30 can be avoided, and the stands ST2, ST3, ST4 can be prevented.
It is possible to avoid the trouble that the tension between them becomes too large or too small. In the above embodiment, the stand S is mainly used.
As mentioned in connection with T3, other stand ST
The control circuits 8, 9, and 11 in 1, ST2, and ST4 have the same configuration.

The plate thickness detecting means and the first speed detecting means are provided at the same place on the inlet side or the outlet side of the tandem rolling mill.

[0037]

The plate thickness control device for a tandem rolling mill according to the present invention has the following effects (1) to (4).

(1) At the start of control of the mass flow AGC immediately after passing the strip, after passing the welding point, immediately after changing the strip thickness, etc., disturbances such as mill setup error, deviation and fluctuation of the strip thickness, and manual intervention of the operator occur most. In the past, this disturbance and the mass flow AGC operation caused a synergistic effect to cause troubles such as plate thickness variation, excessive tension between stands, and insufficient tension. However, in the present invention, the gain of the control means is controlled. By avoiding such troubles by changing the value so that it increases with the passage of time from the start to bring it to a predetermined constant value, the appropriate gain The original plate thickness accuracy can be secured by automatically and smoothly shifting to.

(2) During steady rolling after the completion of rolling acceleration, the original plate thickness is stable and the final finished plate thickness is secured by the operation of various AGCs and is stable. In addition, since it is in a high-speed rolling state, the rolling oil is entrained in the roll bite more than at low speeds, and the work rolls are more likely to slip (the advance rate is negative) than at low speeds. In such a state, the mass flow AGC is not necessary so much. Therefore, when the speed detected by the second speed detecting means on the stand exit side is increased, the gain of the control means is changed so as to be decreased, so that the high speed rolling state is achieved. The gain of can be adjusted to be small, and it is possible to prevent the mass flow AGC from promoting work roll slip and causing a disturbance to the final finished thickness.

On the other hand, in the case of a continuous rolling mill in which a pickling facility, a welding machine and the like are directly connected to the entrance side of the rolling mill, there are cases where the rolling mill speed is reduced to an extremely low speed due to the cause of the directly connected front end. During this acceleration / deceleration, the uniform speed of each stand mill motor and the coefficient of friction of each stand change abruptly, so the plate thickness between each stand tends to change, and at this time it is necessary to increase the gain of the mass flow AGC. According to this, the gain in the low speed rolling state can be adjusted to a large extent by providing the above-described change in the speed gain, and good strip thickness control can be performed.

(3) The excessive work roll slip as described above leads to a flaw in the material to be rolled. When the tonnage of work rolls increases, the roll slip may increase even during low speed rolling. In this case, the mass flow AGC could not be automatically turned off in the prior art, but in the present invention, the advanced rate is negative. Therefore, when the absolute value becomes equal to or larger than the predetermined value, the gain of the control means is held at the predetermined value, whereby the above problem can be avoided.

(4) The mass flow AGC performs the original control only when the stand speed meter between the stands operates normally. However, when the speed meter gives an abnormal value, the mass flow A is detected by the conventional technique.
The GC caused an abnormal operation and caused troubles such as excessive tension or insufficient tension between the stands. However, when the negative absolute value of the advance ratio exceeds a predetermined value, the gain of the control means is set to a predetermined value as described above. By holding so, this trouble can be avoided.

[Brief description of drawings]

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

FIG. 2 is a block diagram showing a specific configuration of control means 17.

FIG. 3 is a graph showing a state in which a coefficient Ci1 in the arithmetic circuit 26 changes.

FIG. 4 is a graph showing a state in which a coefficient Ci2 in the arithmetic circuit 26 changes.

[Explanation of symbols]

 1 strip 2 plate thickness detecting means 3, 4, 5, 6, 7 strip speed detecting means 8, 9, 10, 11 control circuit 12 processing circuit 14 subtraction circuit 15 target value setting circuit 17 control means 24 multiplication circuit 26 arithmetic circuit 27 Seam detecting means 29,34 Work roll speed detecting means 33 Holding circuit 36 Motor 37 Drive circuit ST1 to ST4 Stand

Claims (3)

(57) [Claims] 1. A plate thickness detecting means for detecting a strip plate thickness h0 on an inlet side or an outlet side of a tandem rolling mill, and a first speed detection for detecting a strip velocity v0 at the same place as the plate thickness detecting means of a tandem rolling mill. Means, a second speed detecting means for detecting a speed vi on the exit side of each of the plurality of stands of the tandem rolling mill, a plate thickness detecting means, and a plate in response to outputs from the first and second speed detecting means. The thickness hmi, ## EQU1 ## hmi = (v0.h0) / vi is calculated, and the difference Δhi (= h from the predetermined target plate thickness h0i
mi-h0i), a motor for driving the work roll of each stand, a means for controlling the speed of the motor so that the thickness difference Δhi becomes zero, and a gain of the control means. A plate thickness control device for a tandem rolling mill, comprising: a gain changing unit that changes so as to increase with time from the start of control and brings a predetermined constant value. 2. A plate thickness detecting means for detecting a strip plate thickness h0 on an inlet side or an outlet side of a tandem rolling mill, and a first speed detecting for detecting a strip velocity v0 at the same place as the plate thickness detecting means of the tandem rolling mill. Means, a second speed detecting means for detecting a speed vi on the exit side of each of the plurality of stands of the tandem rolling mill, a plate thickness detecting means, and a plate in response to outputs from the first and second speed detecting means. The thickness hmi, hmi = (v0 · h0) / vi is calculated, and the difference Δhi (= h from the predetermined target plate thickness h0i is obtained.
mi-h0i), a motor for driving the work roll of each stand, a means for controlling the speed of the motor so that the thickness difference Δhi becomes zero, and a gain of the control means. A plate thickness control device for a tandem rolling mill, comprising: a gain changing unit that changes so as to decrease when the speed vi detected by the second speed detecting unit increases. 3. A strip thickness detecting means for detecting the strip strip thickness h0 on the inlet side or the outlet side of the tandem rolling mill, and a strip speed v0 at the same place as the strip thickness detecting means of the stand.
A first speed detecting means for detecting the speed, a second speed detecting means for detecting the speed vi on the exit side of each of the plurality of stands of the tandem rolling mill, a plate thickness detecting means, and a first speed detecting means and a second speed detecting means. In response to the output, the plate thickness hmi, hmi = (v0 · h0) / vi, is calculated, and the difference Δhi (= h from the predetermined target plate thickness h0i is obtained.
mi-h0i), a motor for driving the work roll of each stand, a means for controlling the motor speed so that the thickness difference Δhi becomes zero, and a stand work roll speed vRi. In response to the outputs of the work roll speed detecting means, the second speed detecting means and the work roll speed detecting means, the advanced ratio A, A = (vi-vRi) / vRi is calculated. A tandem rolling mill comprising: a means for obtaining the advance rate A; and a means for holding the gain of the control means at a predetermined value when the advance rate A is negative and the absolute value thereof is equal to or more than a predetermined value. Thickness control device.