JPS643783B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an unwinding machine for winding a strip material, a winding machine for winding the strip material of the unwinding machine, and a braking device for applying braking force during unwinding. The winding machine is rotationally driven by a DC shunt motor, and the DC shunt motor is controlled by voltage control so that its terminal voltage is constant, and by field control so that the back electromotive force is constant. In systems where the excitation current is controlled and the winding speed and tension of the strip across the winder are constant, such as slitting lines and small rolling lines, the tension of the strip across the winder is constant. This invention relates to a control device that keeps the constant constant.

In systems of this type, it is very important to maintain constant tension in the strip. For example, if the tension changes during the rolling operation on a rolling line, the thickness of the product will change, and if the tension changes in a slitting line for aluminum foil or the like, the foil will wrinkle. Therefore, in the past, a detector for the unwinding tension was provided beside the unwinding machine for the strip material, and the braking force of the unwinding machine was controlled based on the detected tension. The tension detector consists of three rolls that meander the strip material to be rewound, and a pressure detector that detects the force applied to the central roll of these rolls. This tension detector is expensive to install, and the roll comes into direct contact with the strip material.
There is a risk that scraps of the strip material may adhere to the roll and cause damage to the strip material. In order to prevent this, it is necessary to periodically inspect the rolls for scratches and adhesion of crumbs to the rolls.

In addition, a touch roll is brought into contact with the strip material being wound around the unwinding machine, and the amount of unwinding is detected based on the amount of displacement of the touch roll. Based on this detection, the unwinding machine is Some control braking force. This method has the advantage of being relatively inexpensive, but depending on the type of strip material, it may
They have the disadvantage that rolls cannot be used in some cases, and the touch rolls come into direct contact with the strip, resulting in the same problems as above.

The present invention provides a constant tension control device for an unwinding machine that has a simple configuration, can be provided at low cost, can be applied to any kind of strip material, does not cause damage to the strip material, and does not require periodic maintenance and inspection. The purpose is to provide.

Hereinafter, embodiments in which the present invention is applied to a rolling line will be described in detail with reference to the drawings.

In FIG. 1, an unwinding machine 1, a rolling mill 3, and a winding machine 2 are arranged in a straight line. Both the unwinding machine 1 and the winding machine 2 are equipped with rotating drums, and the strip material S wound around the drum of the unwinding machine 1 is sent to the winding machine 2 through the compression section 3 and then rolled onto the drum. It is wound up by the rotation of. The drum of the winder 2 is rotationally driven by a DC shunt motor 5 controlled by a static Leonard method (voltage control) and field control, and is controlled so that the winding speed and tension T2 are constant. The rewinding machine 1 is equipped with an air brake 4 as a brake, and this brake 4 applies braking force to the drum of the rewinding machine 1. The braking force of air brake 4 is determined by brake 8
controlled by. A detection signal from a field current detector 7 that detects a field current If flowing through the field winding 5a of the electric motor 5 and a setting output from the tension setting device 9 are input to the controller 8. The output of the controller 8 is sent to an electro-pneumatic converter 6, and the air brake 4 is operated by the compressed air output from the converter 6.
The electro-pneumatic converter 6 has a built-in solenoid valve that is controlled by, for example, an output signal from the controller 8, and the amount or pressure of compressed air sent to the converter 6 is regulated by the solenoid valve. Ru.

Now, in the unwinding machine 1, the radius of the strip material wound around the drum of the unwinding machine 1 (this is referred to as the unwinding diameter) is R1. Tension T1 is applied to the strip material S being rewound.
In order to work, it is necessary to apply a braking torque τ1 given by the following equation to the rewinding machine 1.

τ1=T1・R1 …(1) In order to keep tension T1 constant, braking torque τ1
may be increased or decreased in proportion to the unwinding diameter R1.

In the winding machine 2, the DC shunt motor 5 is controlled by voltage control so that its terminal voltage V is constant, and the exciting current If is controlled by field control so that the back electromotive force E is constant. speed v
When the tension T2 of the strip material S on the side of the winder 2 is constant, the field current If of the electric motor 5 is the radius R2 of the strip material wound around the drum of the winder 2.
(This is called the winding diameter.)

If∝R2 …(2) The reason for this will be explained below.

The electric motor 5 is controlled by the static Leonard method so that the terminal voltage V is constant. Further, the electric motor 5 controls the tension T2 of the winding machine 2 by field control.
is controlled so that it remains constant.

When the rotational speed of the electric motor 5 is N and the winding speed is v, the rotational speed N of the electric motor 5 is expressed by the following equation.

N=v/(2π·R2) (a) Since the strip material S is mechanically connected to the rolling mill 3, the winding speed v is constant. Therefore,
The rotational speed N is inversely proportional to the winding diameter R2 (N∝1/
R2) Do.

When the torque of the electric motor 5 is τ2, the armature current is I, and the back electromotive force is E, the torque τ2 is expressed by the following equation.

τ2=I・E/(2πN) (b) Furthermore, when torque τ2 is expressed by tension T2 and take-up diameter R2, τ2=T2・R2 (c).

From formulas (a) to (c) above, T2・R2=I・E/(2πN) =R2・I・E/v (d) Therefore, T2・v=I・E (f) Back electromotive force If E is controlled so that it is proportional to the winding speed v, the tension T2 becomes proportional to the armature current I. Therefore, by keeping I constant, constant tension control can be achieved.

Since the winding speed v is constant, in order for the back electromotive force E to be proportional to the winding speed v, the back electromotive force E may be made constant.

Also, if the armature resistance is r, then the armature current I
is I=(V-E)/r (g), and since the terminal voltage V is controlled to be constant, when the back electromotive force E is controlled to be constant, the armature current I becomes constant.

That is, if the excitation current If is controlled by field control so that the armature current I is constant, the back electromotive force E becomes constant.

The back electromotive force E is expressed as follows, assuming that the magnetic flux is Φ (Φ∝If). E=K0・Φ・N (h) (K0 is a constant).

Since the back electromotive force E is kept constant, the magnetic flux Φ is inversely proportional to the rotational speed N (Φ∝1/N).

As described above, since the rotational speed N is inversely proportional to the winding diameter R2 (N∝1/R2), the magnetic flux Φ is directly proportional to the winding diameter R2 (Φ∝R2). That is, the exciting current If is directly proportional to the winding diameter R2 (If∝R2).

The method of controlling the back electromotive force E to be constant as described above is called constant back electromotive force control, and is a control method that has been widely used in the field of rolling mill control (Mitsubishi Electric Techniques Vol. .38, NO, 8,
1964, pp. 45-48).

As the winding of the strip S by the winder 1 progresses, the winding diameter R2 increases and the unwinding diameter (R1) decreases, so the winding diameter R2 and the unwinding diameter R1 are similar to each other in inverse proportion. They have a similar relationship.

Therefore, by controlling the braking torque τ1 of the rewinding machine 1 so that the relationship τ1∝T0(1-K・If)...(3) is satisfied, where T0 is the required tension setting value and K is a constant. , tension of one side of unwinding machine
T1 is always kept almost constant.

The controller 8 performs the calculation of equation (3). The field current If detected by the field current detector 7 is amplified by the amplifier 11 and becomes K1·If.
The required tension T0 is set by the tension setting device 9, and this tension T0 is amplified by the amplifier 12.
It becomes K2・T0. The multiplier 13 includes both amplifiers 11,
It multiplies the output of 12, and the output is K1・
It becomes K2・T0・If. The subtracter 14 is the amplifier 12
The output of the multiplier 13 is subtracted from the output of
The subtraction result is K2・T0(1−K1・If),
Corresponds to the right-hand side of equation (3). The output of this subtractor 14 is sent to the electro-pneumatic converter 6 to control the compressed air pressure, so the braking torque of the air brake 4 is
It is controlled to have a value τ1 that satisfies the formula. Strip material S
With the winding and unwinding, the field current If, unwinding diameter R1, winding diameter R2 and braking torque
Changes as shown in the figure.

In this embodiment, it is sufficient to provide only the field current detector 7 as a detector, and there is no need for expensive and large-scale equipment as in the past.
It can be provided at low cost and can be made compact. Further, as the tension setting device 9, for example, a variable resistor can be used, and the configuration is also simple from this point of view. In addition, since the tension T0 can be arbitrarily set by just a knob operation, operation and adjustment are easy.

In the above embodiment, equation (3) is employed to control the braking torque τ1, but this can be done using the following equation, for example.

τ1∝K·T0/If (4) In this way, various calculation formulas for braking torque control can be considered.

A constant tension control device for an unwinding machine according to the present invention includes an unwinding machine around which a strip material is wound, a winding machine on which the strip material of the unwinding machine is wound, and a device for applying braking force to the unwinding machine. The winding machine is rotationally driven by a DC shunt motor, the DC shunt motor is controlled by voltage control so that its terminal voltage is constant, and the back electromotive force is kept constant by field control. In a system where the excitation current is controlled so that the winding speed and the tension of the strip material beside the winder are constant, the unwinding machine is controlled so that the tension of the strip material beside the unwinding machine is kept constant. A device for controlling the braking device of the DC shunt motor, which includes a field current detector for the DC shunt motor, a tension setting device for setting the tension of the strip material next to the unwinding machine,
Based on the detected current detected by the field current detector and the set tension set in the tension setting device, the unwinding machine is controlled so that the tension of the strip material on the side of the winding machine becomes equal to the set tension. It consists of a calculation device that calculates the power, and a control device that controls the braking device so that the braking force of the control device is equal to the braking force calculated by the calculation device, so the tension of the strip material next to the unwinding machine is can always be kept constant. Moreover, the structure is simple and can be provided at low cost, and it can be applied to all kinds of strip materials. Furthermore, there is no risk of damaging the strip material, and regular maintenance and inspection are not required.

[Brief explanation of drawings]

Figure 1 is a block diagram showing the overall configuration of a constant tension control device applied to a rolling line, Figure 2 is a block diagram showing the configuration of the controller, and Figure 3 is a diagram showing various variables associated with winding of a strip material. It is a graph showing changes in. 1... Rewinding machine, 2... Winding machine, 4... Air brake, 5... DC shunt motor, 5a... Field winding, 6... Electro-pneumatic converter, 7... Field magnet current detector,
8... Controller, 9... Tension setting device, 13... Multiplier, 14... Subtractor, S... Strip material.

Claims (1)

[Scope of Claims] 1. An unwinding machine for winding a strip material, a winding machine for winding the strip material of the unwinding machine, and a braking device for applying braking force to the unwinding machine, The winding machine is rotationally driven by a DC shunt motor, and the DC shunt motor is controlled by voltage control so that its terminal voltage is constant, and the exciting current is controlled by field control so that the back electromotive force is constant. In a system in which the winding speed and the tension of the strip material across the winder are constant, the braking device of the unwinder is controlled to keep the tension of the strip material across the unwinder constant. A device comprising: a field current detector for a DC shunt motor; a tension setting device for setting the tension of the strip material on the side of the unwinding machine; and a detection current and tension detected by the field current detector. A calculation device that calculates the braking force of the unwinding machine so that the tension of the strip material on the side of the winding machine becomes equal to the set tension based on the set tension set on the setting device, and a control device that calculates the braking force of the control device. A constant tension control device for an unwinding machine, comprising: a control device that controls a braking device so that the braking force is equal to a braking force calculated by the device.