JPH0919708A - Constant torque controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control load torque of a roll with which a steel sheet is transported by speed control constant by providing a circuit for controlling the torque of a steel sheet transporting equipment which is apt to generate roll slip in a process line constant. SOLUTION: Generally, the generated torque of a motor is proportional to the product of the armature current which flows through the motor and a field magnetic flux. To control the torque constant, the product of the field magnetic flux and the armature current controlled so as to become constant. Then, the constant torque control is controlling the armature current constant. At the time of accelerating and decelerating a line speed, it is necessary to compensate the moments of inertia of the roll and motor, this compensation is determined by calculating the armature current corresponding to the torque determined by the equation and adding it to the command value of the armature current and looseness caused by deficient tension and overtension are prevented. In the equation, Tacc shows acceleration torque, GD<2> the moment of inertia and dN/dt the changing rate of the number of revolution.

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 controlling a load torque of a roll which conveys a steel sheet by speed control in a process line to be constant.

[0002]

2. Description of the Related Art Conventionally, in order to convey a steel sheet in a process line, a line speed command is given to a leonard device (drive equipment) such as a helper roll or a pinch roll that constitutes a drive equipment so that the line speed and the roll circumferential speed are The speed is adjusted by adding roll diameter correction and tension correction functions to the speed command value. However, an analog amplifier is often used in the control calculation unit of the Leonard device, and a calculation error increases due to temperature drift, deterioration over time, and the like, and variations in speed among the Leonard devices increase. When the variation in the speed becomes large, the tension between the respective leonards becomes loose, and it appears as a scratch on the surface of the steel sheet due to the roll slip, which makes the operation impossible.

[0003]

An example of the analog amplifier used in the speed control calculation unit of the Leonard device is as shown in FIG.

Normally, this analog amplifier causes a temperature drift of ± 50 mv to ± 100 mv due to a change in ambient temperature. Assuming that the 100% speed is the 10V command value, the speed change due to this temperature drift corresponds to the speed of 0.5% to 1%, and the speed variation of the Leonard control will occur due to the characteristics of each amplifier. Abnormal tension and looseness will occur. Therefore, in the past, the speed command value was finely adjusted according to the change in the temperature in spring, summer, autumn, and winter to match the circumferential speed of the roll.

[0005]

SUMMARY OF THE INVENTION In the present invention, a circuit for constant control of the torque of a steel sheet conveying facility in which a process line roll slip easily occurs is provided.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a constant torque control loop is newly provided in addition to the conventional speed control closed loop in order to automatically correct the speed change due to temperature drift and match the circumferential speed between rolls. . The constant torque control can be applied to a process line in which the friction torque generated when the steel sheet is conveyed is much smaller than that of the drive motor. That is, torque control becomes possible by controlling the motor current in equipment where the current flowing through the motor has a small amount of friction torque and can be converted into drive torque.

[0007]

FIG. 2 shows an example of actual application of the constant torque control circuit.

It is generally known that the torque generated by the electric motor is proportional to the product of the armature current flowing in the motor and the field magnetic flux.

T = K · Ia · φ (1) where T is torque, K is a constant, Ia is armature current, and φ is field magnetic flux.

To control the torque to be constant, the product of the field magnetic flux and the armature current may be controlled to be constant. Of these, the field magnetic flux has a constant value. Therefore, the constant torque control is a constant control of the armature current. Also, when accelerating and decelerating the line speed, it is necessary to compensate for the moment of inertia of the roll and the motor, but this compensation amount calculates the armature current corresponding to the torque in equation (2), and the armature current is calculated. By adding to the current command value, it is possible to prevent loosening and overtension due to insufficient tension.

[0011] ^{_{T acc = (GD 2/375}} ) · (dN / dt) ... (2) where T _acc acceleration torque, GD ² is the moment of inertia, d
N / dt is the rotational speed change rate.

When the line speed command is constant, if the armature current is set to a range that does not cause roll slip on the power running side, the tension between the rolls will be kept constant through the steel sheet conveyed.

If the armature current command is set to a large value, when the roll slip occurs, the output of the torque control calculation amplifier is limited and the overspeed is prevented.

[0014]

As described above, according to the present invention, it is possible to control the load torque of the roll that conveys the steel sheet in the process line by speed control to be constant.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a constant torque control device of the present invention.

FIG. 2 is a diagram showing an application example of a constant torque control circuit of the present invention to an actual machine.

FIG. 3 is a speed calculation circuit diagram.

Claims (1)

[Claims] 1. A constant torque control device comprising a circuit for constant control of the torque of a steel sheet conveying facility that is prone to roll slip in a process line.