JPH0217615B2 - - Google Patents

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a method for controlling tension in a metal strip threading machine, and in particular, in a metal strip threading machine in which a dancer roll is installed before or after a bridle roll. The present invention relates to a tension control method for reducing tension fluctuations and dancer roll position fluctuations.

[Conventional technology]

When passing a strip through a continuous processing line such as a continuous annealing furnace, for example, in order to prevent surface flaws, heat buckles, walking, or plate breakage, etc.
It is necessary to suppress tension fluctuations in the strip.

In a conventional method for suppressing tension fluctuations, tension fluctuations are suppressed by feeding back a tension signal from a strip tension detection device to a power control system that controls tension in a dancer roll.

In addition, the position of the dancer roll, which has changed to suppress tension fluctuations, is controlled by feeding back the position signal to the speed control system of the bridle roll (for example, in Japanese Patent Application Laid-Open No. (Refer to Publication No. 52-71320).

[Problem that the invention seeks to solve]

However, in this conventional method, since there is hysteresis in the movement of the dancer roll (that is, the amount of current required to maintain a predetermined tension differs depending on the direction in which the dancer roll moves), the movement of the dancer roll is There was a problem in that it could actually induce tension fluctuations. For this reason, especially when it is necessary to suppress tension fluctuations to a small level, this conventional method of suppressing tension fluctuations cannot be applied.

An object of the present invention is to perform control to minimize the movement of the dancer roll in a metal strip threading device in which a dancer roll is installed before or after the bridle roll, and to reduce fluctuations in tension of the strip and fluctuations in the position of the dancer roll. shall be.

[Means for solving problems]

In order to achieve the above object, in the present invention,
In a metal strip threading machine with a dancer roll installed before or after the bridle roll: The detected strip tension before or after the dancer roll is input to the dancer roll tension control device, compared with the tension setting value, and the difference is calculated. The corresponding signal is output as a tension control signal to the dancer roll drive current control device to drive the dancer roll in the direction where the error becomes zero; the dancer roll position control output, bridle roll speed detection value, and bridle roll speed setting value are input. The tension control signal from the dancer roll tension control device is input to a bridle roll speed control device that controls the bridle roll speed to control the bridle roll speed in a direction in which the error becomes zero.

[Effect]

According to this, when the tension detection value deviates from the tension setting value, the dancer roll is driven in a direction to correct it, that is, in a direction to make the deviation zero, and the bridle roll speed is changed. That is, the strip tension is corrected to the tension setting value in both the dancer roll driving force adjustment and the bridle roll speed adjustment. This results in a reduction in the dancer roll driving force and travel amount to compensate for the tension deviation, and reduces the hysteresis of the dancer roll.

Because the dancer roll and the drive system connected thereto have a large inertia, small deviations will substantially compensate for tension deviations by adjusting the bridle roll speed. That is, small tension fluctuations are absorbed by the bridle roll speed adjustment, and large tension fluctuations bring about the dancer roll driving force adjustment. Movement of the dancer roll is therefore minimized. Therefore, with the conventional tension control using only the dancer roll, there is no problem that the movement of the dancer roll itself induces tension fluctuations, and tension fluctuations are reduced. This makes the threading of the strip highly stable, reduces the occurrence of surface flaws and heat buckles, and eliminates the occurrence of walks.

〔Example〕

FIG. 1 shows a metal strip threading apparatus embodying one aspect of the present invention. The metal strip 8 extends from the left side in FIG. 1 to the bridle roll 1, goes around it approximately halfway and reaches the dancer roll 2,
It goes around half a circle to reach the tension detection roll 5, and goes around around half a time to reach the continuous annealing furnace 7. The bridle roll 1 is rotationally driven by a motor 9 in a direction to deliver the metal strip 8 to the dancer roll 2.
The dancer roll 2 is suspended by one end of a wire 28 stretched between rollers 26 and 27. wire 28
A counterweight 4 is suspended from the other end. The roller 27 is rotationally driven by the motor 10, and the dancer roll 2 moves upward or downward.

A dancer roll current control device, which is a servo driver, energizes the motor 10, and the motor 10 rotates forward or reverse depending on the polarity of the energized current.
The rotational torque of is proportional to the absolute value of the current.

The tension detector 6 detects the position of the tension detection roll 5, converts this into a tension value, and sends a signal indicating the tension value, that is, a tension detection signal 12, to the tension control device 1.
Give to 1. The tension control device 11 generates a tension detection signal 12 in response to a set tension signal 13 indicating a set tension value.
A difference signal 14 indicative of the deviation (positive, negative) is applied to the dancer roll current control device 15 and the bridle roll speed control device 23. The dancer roll current control device 15 energizes the current motor 10 corresponding to a signal obtained by subtracting the difference signal 14 from the set tension signal 13 . That is, the motor current feedback signal 16
The motor current is controlled so that the subtracted signal becomes equal to the subtracted signal.

The position of the dancer roll 2 is detected by the position detector 3, and a position detection signal 18 indicating the detected position is given to the dancer roll position control device 19. The position control device 19 outputs a position setting signal 17 indicating the set position.
A position difference signal 20 indicating the deviation (positive, negative) of the position detection signal 18 with respect to the position detection signal 18 is provided to the bridle roll speed control device 23. Bridle roll speed detector 2
5 is a speed detection signal 2 indicating the rotational speed of the motor 9
2 to the bridle roll speed control device 23.

The bridle roll speed control device 23 generates a position difference signal 20 from the sum of the deceleration setting signal 21 and the difference signal 14.
The signal obtained by subtracting is set as a target value (speed instruction value), and the motor 9 is accelerated or decelerated by controlling the motor current 24 so that the speed detection signal 22 becomes this target value.

With the above configuration, when the tension detection signal 12 becomes larger than the set tension signal 13, the difference signal 14 is positive and its absolute value becomes large, and the current flowing through the dancer roll drive motor 10 becomes small, causing the dancer roll 2 to The upward pulling torque becomes smaller.
That is, the tension in the metal strip 8 is reduced.
On the other hand, the target value increases in the bridle roll speed control device 23, the rotational speed of the bridle roll drive motor 9 increases, and the tension in the metal strip 8 decreases. When the tension detection signal 12 becomes smaller than the set tension signal 13, the difference signal 14 is negative and its absolute value increases, the current flowing through the motor 10 increases, and the torque that pulls the dancer roll 2 upward increases. . That is, the tension in the metal strip 8 increases. On the other hand, the target value in the bridle roll speed control device 23 becomes smaller, the rotational speed of the motor 9 decreases, and the tension of the metal strip 8 increases.

Through such an operation, the tension of the metal strip 8 is controlled to a tension determined by the set tension signal 13.
In this way, the pulling torque control of the dancer roll 2 and the speed control of the bridle roll 1 are performed so that the difference signal 14, that is, the tension deviation, is zero (the tension control by the speed control of the bridle roll 1 is added). ), when a tension deviation occurs, the compensation operation to make it zero becomes faster, and the amount of change in the dancer roll driving force and movement amount for compensation becomes smaller, which reduces the hysteresis of the dancer roll 2. It turns out.
Furthermore, since the responsiveness of the speed control of the bridle roll 1 is higher than the responsiveness of the tension control of the dancer roll 2, when the tension deviation (difference signal 14) is small, the bridle The tension control effect by speed control of the roll 1 appears, the difference signal 14 becomes zero, and the tension control by the dancer roll 2 has no effect. That is, small tension fluctuations are absorbed by the speed control of the bridle roll 1, and the movement control of the dancer roll 2 is not performed. If there is no movement of the dancer roll 2, there will be almost no large tension fluctuations, and the threading of the strip 8 will be extremely stable.

FIG. 2 shows an example of test results showing the control effect obtained by applying the method of the present invention.

In this test, a strip having a thickness of 0.6 mm and a width of 1200 mm was passed through a continuous annealing furnace 7 as shown in FIG. 1 at a target threading speed of 200 m/min.

In FIG. 2, A on the left is a graph showing strip tension and dancer roll position when conventional tension control is used, and B on the right is a graph showing strip tension and dancer roll position when the present invention is implemented as described above. It is a graph. represents the dancer roll position, represents the tension of the metal strip 8 in the continuous annealing furnace 7, and represents the tension of the dancer roll 2. Comparing A (conventional) and B (invention), it can be seen that according to the invention, the variation in strip tension is reduced, and the variation in the position of the dancer roll is also reduced.

〔Effect of the invention〕

As described above, in the method of the present invention, the positional fluctuation of the dancer roll is almost constant, the tension fluctuation is extremely small, and the tension control is performed extremely well. The amount of movement of the dancer roll is kept to a minimum. In other words, all small tension fluctuations are absorbed by the tension control by speed control of the bridle roll, and only when a large tension fluctuation occurs, the tension control system by current control of the dancer roll is activated, causing the dancer roll to move. Therefore, the movement of the dancer roll itself does not induce tension fluctuations, which is a disadvantage of tension control using only dancer rolls, and it is possible to minimize tension fluctuations in tension control of metal strip threading equipment. can.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a metal strip threading device implementing the present invention in one embodiment, and FIG. 2 is a graph showing test results B in which the present invention was implemented in one embodiment together with test results A based on the conventional method. be. 1: Bridle roll, 2: Dancer roll,
3: Dancer roll position detector, 4: Counterweight, 5: Tension detection roll, 6: Tension detector, 7: Continuous annealing furnace, 8: Metal strip, 9:
Bridle roll drive motor, 10: Dancer roll vertical drive motor, 11: Tension control device, 1
2: Tension detection signal, 13: Setting tension signal, 14:
Difference signal, 15: Dancer roll current control device, 1
6: Motor current feedback signal, 17: Position setting signal, 18: Position detection signal, 19: Dancer roll position control device, 20: Position difference signal, 21:
Speed setting signal, 22: Speed detection signal, 23: Bridle roll speed control device, 24: Motor current,
25: Bridle roll speed detector, 26,2
7: Roller, 28: Wire.

Claims (1)

[Claims] 1. In a metal strip threading device in which a dancer roll is provided before or after a bridle roll: A detected value of the strip tension before or after the dancer roll is input to a tension control device for the dancer roll,
It compares the tension with the set tension value and outputs a signal corresponding to the difference as a tension control signal to the dancer roll drive current control device to drive the dancer roll in the direction where the error becomes zero; dancer roll position control output, bridle roll speed The tension control signal from the dancer roll tension control device is input to a bridle roll speed control device that receives the detected value and the bridle roll speed setting value and controls the bridle roll speed, and controls the bridle roll speed in the direction in which the error becomes zero. Tension control method for metal strip threading equipment.