JPH0716629A - Bridle roll controller for rolling mill - Google Patents

Abstract

PURPOSE:To prevent the occurrence of a slip and slip defects at the time of flying cutting in bridle rolls to be used at the outlet side of a continuous cold rolling mill. CONSTITUTION:At the time of flying cutting of a strip, specified control is carried out on the speed of the bridle rolls 3a-3d only for a specified period W1. In addition, when a snubber roll is used at the time of flying cutting, load distribution of the respective bridle rolls 3a-3d is changed and controlled for the specified period W1. Before the time t1 and after the time t8, the snubber roll 8 is separated from the bridle roll 3d by a cylinder 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a bridle roll device installed on the exit side of a rolling mill for strip such as cold rolled steel strip.

[0002]

2. Description of the Related Art On the delivery side of a cold rolling mill, there is a prior art in which a bridle roll is installed in addition to a take-up reel in order to stabilize the shape and rollability by applying a high tension to a steel strip. For example, as shown in FIG. 6, a bridle roll device 3 is installed between the rolling mill body 2 and the carousel reel 6.

Further, recently, a technique has been developed in which a welding machine 1 is provided on the inlet side of the rolling mill so as to avoid passing through the rolling mill and punching work, or by connecting to a pickling line or the like and continuously rolling. I've been In this case, a running shear 5 and a carousel reel 6 are provided on the delivery side of the rolling mill to continuously cut and wind the steel strip.

Each of the rolls of the bridle roll device 3 usually has a hardness of Shore hardness Hs80 or more in order to obtain a high tension and to prolong the life of the bridle roll device. In many cases, this is done, or thermal spraying of ceramics, cermets, etc. is performed and dull shot processing is also performed.

When the exit side bridle roll device 3 is used in the above continuous rolling mill, the following problems occur when the steel strip is cut by the running shear 5. Explaining with reference to FIG. 6, when the steel strip 7 is cut by the running shear 5, the tension between the take-up reel 6a and the bridle roll device 3 disappears, and the steel strip of the succeeding material is wound around the standby reel 6b. , This state continues. In the absence of this tension, it is difficult for the leading end of the steel strip of the succeeding material to pass through to the standby reel 6b. Therefore, a pinch roll 4 is separately provided between the bridle roll device 3 and the running shear 5, and some tension is applied. I am maintaining.

However, the tension of the pinch roll 4
Since it is not always used, the tension is usually designed to be the minimum tension, and therefore, the tension is significantly lower than the tension applied to the take-up reel 6a. For this reason, it is inevitable that the tension on the downstream side of the bridle roll device 3 (that is, the reel 6 side) suddenly changes at the moment when the running is cut. Due to this sudden change in tension, the bridle rolls 3a to 3d and the steel strip 7 may slip, causing flaws in the steel strip, which may seriously affect the quality of the product.

In the prior art for solving this problem,
Another snubber roll 8 is provided so as to come into contact with the most downstream bridle roll 3d, and the contact pressure is reduced for a certain period before and after traveling cutting, so that a tension higher than that of the small pinch roll 4 is produced. In this case, since the snubber roll 8 does not perform rolling work and only makes line contact, the bridle rolls 3a to 3c closer to the mill main body 2 than the snubber roll 8 avoid a sudden change in tension at the moment of shear running. I can't. At this time, the other bridle rolls 3 a to 3 not attached to the snubber roll 8
In c, the rolls 3a to 3c and the steel strip may slip due to this sudden change in tension, which may cause flaws in the steel strip.

As a result of various investigations, the cause of this flaw is
It was found that the high places of the roughness convex portions of the bridle rolls 3a to 3c at the time of the dull processing slipped with the steel strip 7 at the time of a sudden change in the tension at the time of traveling cutting, thereby causing a flaw.

On the other hand, when the bridle rolls 3a to 3d themselves are used for a long period of time, the dulls on the surface become worn and become smooth, so that the steel strip 7 and the bridle rolls 3a to 3d easily slip during normal operation. The required tension cannot be maintained on the outlet side of the mill body 2. Therefore, as the bridle rolls 3a to 3d themselves, it is desired to use bridle rolls having as large a roughness as possible, as long as no dull marks are left on the marks. By doing so, the replacement cycle of the bridle rolls 3a to 3d can be extended. That is,
Bridle rolls with low roughness are required to prevent flaws in steel strips due to rapid changes in tension during cutting during running.
In terms of the life of the roll itself, there is a contradictory situation that a roll with high roughness is required.

[0010]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and the bridle roll itself can have a long life without slipping when the running cut is performed. The purpose is to provide the device.

[0011]

SUMMARY OF THE INVENTION The present invention is a bridle roll device having a bridle roll and a running shear on the rolling mill outlet side, and during normal operation, constant tension control or constant current control on the rolling mill outlet side is performed. The bridle roll control device for a rolling mill is characterized in that the strip is operated under constant speed control only for a certain period before and after the strip running.

Further, the present invention has a plurality of bridle rolls on the delivery side of the rolling mill, has a snubber roll which comes into contact with any one of the rolls, and further has a bridle roll device having a running shear, in which each ordinary bridle roll is provided. A bridle roll control device for a rolling mill, characterized in that the load distribution of each bridle roll is changed only for a certain period during the reduction of the snubber roll before and after the strip is cut while the strip is running.

Further, the present invention is characterized in that the load of the bridle roll on the most downstream side in the sheet passing direction is set to be larger than that of the remaining bridle rolls.

[0014]

According to the present invention, during normal operation, that is, during the period during which strip running is not cut, the tension on the delivery side of the rolling mill is controlled to be constant, or each bridle roll in the bridle roll device is controlled. The load current of the motor to be driven is controlled to be constant, and the speed is controlled to be constant during a certain period before and after the disconnection between running runs, so that the peripheral speed of the bridle roll and the strip passing speed are the same. It is kept at a value and therefore there is no slippage between the surface of the bridle roll and the strip, thus preventing the surface of the strip from being scratched. After the lapse of the certain period, the control mode is returned so that the tension of the strip becomes constant or the load current of the motor that drives the bridle roll becomes constant.

Further, according to the present invention, at least one roll of the plurality of bridle rolls is contacted with the snubber roll for a certain period of time before and after the strip is cut while the strip is stripped between the snubber roll and the bridle roll. The bridle roll load distribution is changed from the normal load distribution other than that for a certain period of time during which the snare roll is clamped, whereby a strip is formed in the bridle roll on the upstream side in the threading direction of the bridle roll in which the snubber roll is in pressure contact. Slippage can be prevented, which can prevent the strip from being scratched.

According to the present invention, the bridle roll against which the snubber roll is pressed is the bridle roll arranged on the most downstream side in the sheet passing direction, and the load on the most downstream bridle roll is the remaining bridle roll. Larger than this so that no slippage occurs between the upstream bridle roll and the strip.

[0017]

EXAMPLE In the cold rolling equipment shown in FIG. 1, a cold rolled steel strip 7 exiting from a rolling mill mill main body 2 from a welding machine is continuously connected to a take-up reel 6a of a carousel reel 6 via a bridle roll device 3. Has been rolled up. The bridle roll device 3 is provided with a motor 11a in order to apply a tension higher than the tension wound by the take-up reel 6a on the exit side of the mill body 2.
I'm working hard at ~ 11d. Bridle roll device 3
Has four bridle rolls 3a to 3d, and each bridle roll 3a to 3d is rotationally driven by each motor 11a to 11d. A pinch roll 4 is provided further downstream than the most downstream bridle roll 3d in the sheet passing direction, and clamps the steel strip 7. Further, a running shear 5 is provided on the downstream side. A tensiometer 9 for detecting the tension of the steel strip 7 is provided between the mill body 2 and the bridle roll 3a. This embodiment bears the same reference numbers on corresponding parts of the prior art described in connection with FIG. 6 above.

In FIG. 1, considering the moment when the steel strip is wound up to the required diameter by the take-up reel 6a and then cut by the running shear 5, the pinch roll 4 secures some tension. However, at the moment of cutting, the tension on the exit side of the bridle roll 3 suddenly drops. At this time, the motor current constant control of the normal bridle rolls 3a to 3d and the constant tension control of the tension meter 9 installed on the exit side of the mill main body 2 are performed for the motors 11a to 11d of the bridle rolls 3a to 3d.
Bridle rolls 3a-3d
It is unavoidable that the peripheral speed changes rapidly. When the peripheral speeds of the bridle rolls 3a to 3d and the speed of the steel strip are unmatched, the extreme convex portions of the dulls of the bridle rolls 3a to 3d may scratch the steel strip 7.

This situation will be further described. When the constant tension control of FIG. 1 is performed, each bridle roll 3a-
3d is rotated by each of the motors 11a to 11d, and the controller 10 performs feedback control of the signal by the tensiometer 9. As a control method, ordinary P · I (proportional / integral) control or the like is used. That is, in response to the output of the tensiometer 9, the currents of the motors 11a to 11d are controlled so that the tension becomes a target value.

FIG. 2 shows a situation in which the steel strip is cut by the running shear 5 while the constant tension control is being performed. The tension at the exit side of the mill is controlled to be constant until just before the cutting during running, and the peripheral speed of the bridle roll and the bridle roll current are relatively stable. FIG. 2 (1) is a diagram showing the tension of the steel strip 7 on the delivery side of the mill main body 2.
(2) is a diagram showing the peripheral speed of the bridle roll 3d,
FIG. 2C shows a motor 1 for driving the bridle roll 3d.
It is a figure which shows the load current of 1d, and FIG. 2 (4) shows the supply speed from the mill main body 2 of the steel strip 7. Before time t1,
Normal rolling work is being performed, and when the time to cut at the running shear 5 approaches, the tension is reduced and time t2 is reached.
After that, the tension is kept constant.

Conventionally, after the running cut is performed at the time t4, the tension on the delivery side of the mill is instantaneously reduced to only the tension applied by the pinch roll 4. At this time, since the bridle rolls 3a to 3d have reduced tension,
There is a command to increase the current. On the other hand, the roll peripheral speed is lost by the running cut, while the rotational torque was assisted through the steel strip by the reel tension of the motors 11a to 11d themselves. Therefore, the speed drops a little, and after this,
The speed is increased by the feedback of the tension control.
During this time, this occurs even if the speed of the steel strip on the mill exit side is unchanged. That is, the bridle roll 3a-
Since the speed change of 3d is not synchronized with the speed of the steel strip, a slip between the steel strip and the bridle roll occurs. The operation in such a prior art is as shown by the solid line in FIG.

As a measure against this problem, according to the present invention, the operation is performed as shown by the broken line in FIG. 2, and in order to perform such operation, the control circuit as shown in the flow chart of FIG. Add 10. In step n1,
It is determined whether or not it is a predetermined period W1 before and after the shear cut that is from time t3 to t6. This period W1 means a certain time before the cutting during running, or a certain length after the cut point of the steel strip reaches the shear 5, a certain time after the reel winding is completed, or the cut point of the steel strip reaches the reel. It is between the arrival and the winding of a certain length. The welding position of the coil of the steel strip by the welding machine along with the traveling of the steel strip 7 can be calculated and obtained by detecting the traveling distance, whereby the time W1 can be obtained.
Can be calculated and obtained. Further, if the determination that the period is W1 is YES, step n2
If NO, go to step n3. In step n3, the tension of the steel strip 7 is set to be constant at each target value and negative feedback control is performed by all the bridle rolls 3a to 3d. In step n2, all bridle rolls 3a to 3d are controlled to a constant speed control.

By doing so, the bridle rolls 3a to 3 which have conventionally been generated from after the cutting of the running to the completion of the winding.
The slip caused by not synchronizing the speeds of d and the steel strip 7 is eliminated. As a specific content of the constant speed control, each bridle roll speed at the start of the constant speed control is held as a target value as it is. That is, each bridle roll 3a-3d
A speed detector for detecting the speed of
During a period W1 of t6 to t6, the speeds of the bridle rolls 3a to 3d detected at time t3 are stored as target values, and the motors 11a to 11d are stored so that the target values are maintained.
11d is controlled by negative feedback.

As another embodiment, the mill outlet steel strip speed is detected by another means so as to have the same value. That is, a speed detector for detecting the speed of the steel strip 7 is provided on the outlet side of the mill body 2, and the speed detected at time t3 is set as a target value.
The speed of d is negatively feedback controlled.

After the running-off period W1 has passed, time t
Return to the original tension feedback control after 6
After the time t8, the original bridle rolls 3a to 3d are provided with the mill exit side tension increase, which is the function of the original bridle rolls 3a to 3d.

In another embodiment of the present invention, the snubber roll 8 of FIG. 1 is further provided. This roll 8 is subjected to contact pressure reduction for a certain period before and after cutting during running, and the bridle rolls 3a to 3
Along with d, the tension from the traveling cutting to the completion of winding is maintained as much as possible to secure the required outlet tension of the mill main body 2. Even in the case of the bridle roll device 3 having such a configuration, the bridle rolls 3a to 3c upstream of the bridle roll 3d having the snubber roll 8 have been conventionally configured as shown in FIG.
The situation shown by the solid line in Fig. 2 may occur, causing slippage.

As a countermeasure at the time of running cut using the snubber roll 8, a motor 11 for rotating the bridle roll 3d which does not slip with the steel strip 7 under the pressure of the snubber roll 8 is produced.
Motor power is distributed with emphasis on d. At this time, the other rolls 3a, 3b, 3c without the snubber roll 8 give load distribution to the extent that slipping does not occur. By doing so, the bridle rolls 3a to 3d can be used to the maximum during the period W1 from immediately before shear cut to the completion of winding of the take-up reel, and the original bridle roll function, that is, the tension on the delivery side of the mill can be increased.

Therefore, the operation as shown in FIG. 4 is performed by the control circuit 10. At step m1, it is judged whether or not it is W1 for a certain period before and after the shear cut. This period is the same as n1 in FIG. 3, and the condition that “the snubber roll 8 is under pressure” is determined. Furthermore, if the determination in step m1 is YES, step m2
If NO, the process proceeds to step m3. In step m2, assuming that the bridle rolls 3a to 3d after running cut have no tension on the exit side, the load is concentrated on the motor 11d, and the remaining rolls 3a to 3c are loaded to such an extent that no slip occurs. Give allocation. After this period W1,
Return to original feedback control. That is, when the snubber roll 8 is used before and after the running cut, the load of each bridle roll 3a to 3d is changed and controlled at the same timing as described above. The flaw is gone.

For load distribution, constant tension on the outlet side of the mill is controlled as follows. The loads of the motors 11a to 11d, that is, the load currents are indicated by reference signs a, b, c, and d, respectively. During normal operation, that is, before the time t1 in FIG. 2 in which the inter-running disconnection is not performed, the period from the time t2 to t3, the period from the time t6 to t7, and the time t8 or later, it is determined as shown by the solid line in FIG.

A <b <c <d (1) These loads a to d are approximately approximate values.

In the period W1, the loads a to d are set as shown by the solid lines in FIG. 5, that is, d >>a>b> c (2) In the equation 2, the loads a, 11a to 11c of the motors 11a to 11c. b, c
Is an approximate value, and the load d of the motor 11d that drives the bridle roll 3d on the most downstream side in the sheet passing direction is selected to be a sufficiently large value as compared with them. This can prevent the steel strip 7 from being damaged by the bridle rolls 3a to 3d.

In an experiment conducted by the present inventor, in a continuous cold rolling mill having a welding machine on the inlet side of the mill body 2, bridle rolls 3a to 3d on the outlet side, and subsequently a carousel reel 6, the bridle roll 3 was , 800mmφ is used in a set of 4. With this equipment, when the shear cut position of the steel strip reached the mill main body, switching to constant speed control as described above, and performing control to return after reeling 3 reels after reel winding, it has occurred conventionally. In addition, the defect due to the slip of the bridle roll 3 disappeared.

[0033]

As described above, by carrying out the present invention in a continuous cold rolling mill having a bridle roll device, slip between the bridle roll and the steel strip and the resulting flaw in the strip during cutting during running can be prevented. It will not occur.

Further, according to the present invention, it is possible to employ a bridle roll having a relatively rough surface, and it is possible to reduce the cost of exchanging the bridle roll and processing.

Further in accordance with the present invention, snavalol is
By changing the load distribution of the bridle rolls during the period before and after the strip is cut so as to be different from the load distribution of the bridle rolls in the other period while being pressed against at least one of the plurality of bridle rolls. Can be utilized to the maximum and contribute to the quality improvement of steel strip.

The snubber roll 8 is driven by, for example, a double-acting hydraulic cylinder 12. This snubber roll 8
It may be provided in association with the other bridle rolls 3a to 3c.

[Brief description of drawings]

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

FIG. 2 is a diagram for explaining the operation of the embodiment shown in FIG. 1 and for explaining the operation of the prior art.

FIG. 3 is a flow chart for explaining an operation when the operation is performed with a constant speed control in a constant period W1 before and after the running cut of the steel strip 7 in one embodiment of the present invention.

FIG. 4 shows the operation of driving the snubber rolls 8 during a certain period W1 before and after the running of the steel strip 7 in another embodiment of the present invention, and setting the load distribution of the bridle rolls different from the remaining period. It is a flow chart for explaining.

5 is a diagram showing load distribution of motors 11a to 11d driving bridle rolls 3a to 3d in the embodiment shown in FIG.

FIG. 6 is a block diagram showing an overall configuration of a prior art.

[Explanation of symbols]

 1 Welding machine 2 Mill body 3 Bridle roll device 3a-3d Bridle roll 4 Pinch roll 5 Running shear 6 Reel 7 Steel strip 8 Snubber roll 9 Tensiometer 10 Controller 11a-11d Motor

Claims (3)

[Claims] 1. A bridle roll device having a bridle roll and a running shear on the delivery side of the rolling mill, during normal operation, constant tension control or constant current control on the delivery side of the rolling mill is performed to control the strip before and after strip running. A bridle roll controller for a rolling mill, which is operated by constant speed control only for a certain period. 2. In a bridle roll device having a plurality of bridle rolls on the delivery side of the rolling mill, a snubber roll in contact with any one of the rolls, and a running shear, a load of each ordinary bridle roll is provided. A bridle roll control device for a rolling mill, characterized in that the load distribution of each bridle roll is changed only for a certain period of time during the reduction of the snubber roll before and after the strip is cut while running. 3. The bridle roll control device for a rolling mill according to claim 2, wherein the load of the most downstream bridle roll in the sheet passing direction is set to be larger than that of the remaining bridle rolls.