JPH04256655A - Helper roll drive controlling method on strip process line - Google Patents

Abstract

PURPOSE:To preclude production of scratches resulting from poor performance of helper roll rotation, and prevent a helper roll driving motor from tripping which is caused by abnormal tension on a strip, by incorporating a helper roll drive control method according to the invention in the process line. CONSTITUTION:The peripheral speed of a helper roll 3 and the running speed of a strip 1 are sensed, and when the former becomes lower than the latter, or when tone line is accelerated or decelerated, a torque shall be generated in a helper roll driving motor 5. Therefore, there is no risk of producing scratches on the surface of the strip due to poor performance of helper roll rotation. By the strip 1 the helper roll driving motor 5 is turned to cause the generating operation, and there is no risk of the motor 5 tripping upon receiving from the strip 1 a torque exceeding the mechanical loss.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling the drive of a helper roll in a strip processing line such as a continuous annealing line for steel strips.

0002

[Prior Art] Usually, the conveyor rolls in the process line are
As shown in FIG.
It is equipped with a helper roll 3 for holding. The bridle roll 2 is driven by a bridle roll drive motor 4 having sufficient capacity to create tension in the strip 1. The tensions T0 and T1 before and after the bridle roll shown in FIG. 5 are T1 > T0 or T1 > T depending on the torque of the bridle roll 2
It usually changes to 0.

On the other hand, in the helper roll 3, since the purpose is not to change the tension at the front and rear of the roll,
The tension is the same value T0 before and after the roll (see Figure 6).
. Since it is used in this way, the torque given to the helper roll 3 is sufficient to compensate for the mechanical loss of the roll itself, so either the motor 5 has a small capacity enough to compensate for the mechanical loss value, or In the case of small rolls, it was customary to use a non-drive type without a motor to reduce costs.

In FIG. 4, 6 is a speed control device for the bridle roll drive motor 4, and 7 is a speed control device for the helper roll drive motor 5.

[0005]

[Problem to be Solved by the Invention] However, if a rotation failure occurs in the helper roll when the helper roll drive motor is set to non-drive, the mechanical loss of the helper roll itself increases, and the helper roll becomes unable to rotate. Scratches occur. In addition, even when driving with a helper roll drive motor, if the speed adjustment of the helper roll drive motor does not match the threading speed and the strip speed is faster than the speed of the helper roll drive motor, the motor may be This resulted in a generating operation in which the strip was rotated, and the strip received more torque than the mechanical loss, causing problems such as tripping.

The present invention solves the problems of the prior art described above,
It is an object of the present invention to provide a helper roll drive control method in a process line that can prevent the occurrence of scratches due to poor rotation of the helper roll, and can also prevent tripping of the helper roll drive motor due to abnormal tension in the strip.

[0007]

[Means for Solving the Problems] The present invention is a method for controlling the drive of a helper roll that conveys a strip in a process line that continuously processes the strip, and in which the number of rotations of the helper roll and the running speed of the strip are controlled. A method for controlling drive of a helper roll in a strip processing line, comprising: detecting that the circumferential speed of the helper roll becomes slower than the running speed of the strip, and generating torque in a helper roll drive motor when the line accelerates or decelerates. The present invention is also characterized in that the running speed of the strip is determined from the circumferential speed of the bridle roll closest to the helper roll group.

[0008]

[Operation] Detects the circumferential speed of the helper roll and the running speed of the strip, and when the circumferential speed of the helper roll becomes slower than the running speed of the strip or when the line accelerates or decelerates,
Since the helper roll drive motor is controlled to generate torque, scratches will not be generated on the surface of the strip due to poor rotation of the helper roll. Further, the helper roll drive motor is rotated by the strip and becomes a generating operation, so that the helper roll drive motor does not trip due to receiving a torque exceeding mechanical loss from the strip.

Furthermore, by determining the running speed of the strip from the circumferential speed of the bridle roll closest to the helper roll group, the running speed of the strip can be reliably determined without the need for a special measuring device, and control accuracy can be improved. will also be good.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an example of an apparatus suitable for carrying out the method of the present invention. In FIG. 1, 1 is a strip such as a steel strip, 2 is a bridle roll for generating tension in the strip 1, and 3 is a helper roll for holding the strip 1.

The bridle roll 2 is driven by a bridle roll drive motor 4 having sufficient capacity to create tension in the strip 1. Further, 5 is a small-capacity helper roll drive motor as described above, and 7 is a speed control device for the helper roll drive motor 5. In this device, a main circuit on/off device 8 is provided between the helper roll drive motor 5 and the speed control device 7. Whether the main circuit on/off device 8 is turned on or off is determined by the comparison between the traveling speed of the strip 1 and the circumferential speed of each helper roll 3, as will be described later.

Here, the circumferential speed of each helper roll 3 is determined by a speed detector 9 attached to the helper roll drive motor 5. Note that since it is practically difficult to directly measure the running speed of the strip 1, the circumferential speed of the bridle roll 2 closest to the 3 groups of helper rolls is taken as the running speed of the strip 1. The circumferential speed of the bridle roll 2 may be determined by a speed detector 10 attached to the bridle roll drive motor 4.

The circumferential speed of the bridle roll 2 and the circumferential speed of each helper roll 3 are compared by a speed comparator 11, and the following control is performed based on the result. If the circumferential speed of the helper roll 3 is slower than the circumferential speed of the bridle roll 2 by a certain amount or more, it is determined that the helper roll 3 needs to be driven, the main circuit on/off device 8 is turned on, and the helper roll 3 is driven. Start. When the driven helper roll 3 starts rotating faster than the peripheral speed of the bridle roll 2, that is, the running speed of the strip 1 by a certain amount or more, it is determined that the drive of the helper roll 3 is no longer necessary. The main circuit on/off device 8 is turned off to prevent abnormal current from flowing due to generating.

On the other hand, when the circumferential speed of the helper roll 3 does not become slower than the circumferential speed of the bridle roll 2 by more than a certain amount, the mechanical loss of the helper roll 3 is minute, and the torque corresponding to the mechanical loss is It is determined that the strip 1 is being fed smoothly to the helper roll 3, and the operation is continued with the main circuit on/off device 8 kept in the OFF state.

In addition to the above-described control, generation of scratches due to poor rotation of the helper roll 3 can be prevented by generating torque in the helper roll drive motor 5 when the line is accelerated or decelerated. Next, a specific example of the present invention will be described in comparison with a conventional example. Fig. 2 shows an example of the helper roll speed and current pattern when the present invention is used in a steel strip process line, and Fig. 3 shows an example of the helper roll speed and current pattern using the conventional main control system. Each is shown below.

In the conventional control system of FIG. 3, the helper roll attempts to rotate according to the same speed criterion as the bridle roll. When the steel strip accelerates, the helper roll also accelerates, and when the steel strip decelerates, the helper roll also decelerates. Furthermore, if the mechanical load on the helper roll increases, the load current is increased to keep the rotation speed constant. Also, when the helper roll is operating smoothly, only a small load current flows. In this way, there is no problem during normal operation, but if a disturbance occurs in the line and the tension of the steel strip increases abnormally, the steel strip turns the motor, causing an abnormal regenerative current to flow. become. As a result, the circuit trips and the control device recognizes that an abnormality has occurred and stops the line.

In the case of the method of the present invention shown in FIG. 2, the main circuit of the helper roll is closed only when a load is applied during acceleration and deceleration, and the main circuit is opened and free-run when no load is applied. Driving. If the speed of the helper roll becomes slow for some reason, it is determined that it is necessary to drive the helper roll, and the main circuit is closed and current is applied to drive the helper roll. Furthermore, even if a disturbance occurs in the line and abnormal tension occurs, as long as the helper roll is free running, no abnormality such as tripping will occur and smooth operation can be continued.

[0018]

[Effects of the Invention] As explained above, according to the present invention, in the strip processing line, only when necessary,
Mechanical losses in the helper roll can be compensated for, and scratches caused by poor rotation of the helper roll can be prevented. Further, it is possible to prevent tripping due to abnormal current generation in the helper roll due to abnormal tension in the line, and the line can be operated stably.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an example of a device suitable for carrying out the method of the present invention.

FIG. 2 is a graph showing a specific example of the present invention.

FIG. 3 is a graph showing a specific example of a conventional control system.

FIG. 4 is an explanatory diagram of an example of a conventional process line device.

FIG. 5 is an explanatory diagram showing the tension acting on the strip before and after the bridle roll.

FIG. 6 is an explanatory diagram showing the tension acting on the strip in the helper roll.

[Explanation of symbols]

1 Strip 2 Bridle roll 3 Helper role 4 Bridle roll drive motor 5 Helper roll drive motor 6 Bridle roll speed control device 7 Helper roll speed control device 8　Main circuit on/off device 9 Speed detection device 10 Speed detection device 11 Speed comparison device

Claims (2)

[Claims] 1. A method for controlling the drive of a helper roll that conveys a strip in a process line that continuously processes the strip, the method comprising: detecting the rotational speed of the helper roll and the running speed of the strip, and controlling the peripheral speed of the helper roll; 1. A method for controlling a helper roll drive in a strip processing line, the method comprising: generating torque in a helper roll drive motor when the running speed of the helper roll becomes slower than the running speed of the strip and when the line is accelerated or decelerated. 2. The helper roll drive control method in a strip process line according to claim 1, wherein the running speed of the strip is determined from the circumferential speed of the nearest bridle roll in the helper roll group.