JPS602558A - Control of tension of strip - Google Patents

Abstract

PURPOSE:To keep the tension of a strip at a constant value by maintaining the speed of said strip in proportion to the reverse electromotive potential of a direct current motor which drives a winder for winding and unwinding of said strip. CONSTITUTION:The invention relates to a control method for the tention of a strip wherein the tension of said strip is kept at a constant value by maintaining the speed V of said strip in proportion to the reverse electromotive potential of a direct current motor 18 which drives a winder 16 for winding and unwinding said strip, the tension of said strip is kept at a constant value in such a way that the reverse electromotive potential signal Ea is obtained from the terminal potential signal of the armature of a direct current motor and the resistance potential decrease signal of said armature, the speed signal of said strip is obtained by multiplying the rotation speed signal of a roller 12 by the proceeding rate or the receding rate which can be defined from the potential decrease rate and the tension of said strip, and the field current Ib of said direct current motor is controlled so that the speed signal of said strip may be maintained in proportion to said reverse electromotive potential signal.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for controlling strip tension, and in particular to a method for controlling strip tension and a back electromotive force in a DC motor that drives a winder for winding or unwinding a strip. This relates to a method of controlling strip tension in which the strip tension is maintained constant by maintaining a proportional relationship.

The strip tension is expressed by the armature current of the DC motor for driving the winder, when the back electromotive voltage of the DC motor for driving the winder is matched with the strip conveyance speed (hereinafter simply referred to as strip speed). Control using this relationship is called winder back electromotive voltage control.

That is, to briefly explain this back electromotive force control, the winding tension (= strip tension) F (kg) is defined as the winding radius at that point r (m), and the winding moment FXr is the DC motor. It should be equal to the generated torque l-m (kg-■), so it can be written as equation (1).

F = Tm/, r---(1) On the other hand, the armature terminal voltage of the DC motor is (times/5ec), the magnetic flux generated by the field current I[(A) is expressed as φ(wb), the generated torque Tn+(kg-m) of the DC motor, the back electromotive force [:a (v
olt) can be obtained as shown in equations (2), (3), and (4) using the constants vik+ and k2, as is well known.

Tl1l = +φIa---, (2> Ea = V-IaR---(3) = k2φN...(4) Here, the number of rotations of the winding machine at that point is 1) (times/ se
c), since n is proportional to the armature rotation speed N,
It can be written as equation (5) using 3 as a constant, and since the strip speed v (m/sec) can be calculated as shown in equation (6), equations (7) and (8) hold true.

n=kaN・・・・・・(5) V yo 2πrn contest Φ・Contest number・(6) −2πrk3N・・・(7) r=v/2yrk 3N−・(8) In equation (1), (2
Substituting the relationship in equations >(4)<8) yields equation (9).

F-1-m/r -1ku 1 φ la / (V /27rk 3 N
＞=k + X (Ea /k 2 N)X Ia
/ (V /27rk 3N) = 2k 1k 37r/
k 2 xEa /v
) can be expressed as equation (11).

Ea/V=ka (k< is a constant)---(10)F-2
k l k 3π/k 2 Xk, 4 X 1a=K
Ia (K is a constant)---(11) This (10)
Equation (11,) shows that if the back electromotive force Ea is made to follow the stripping speed V to maintain a proportional relationship -4, the strip tension F can be controlled to an arbitrary magnitude proportional to the armature current 1a. It means seven. Back electromotive force control utilizes this relationship.

In the strip tension control method that employs the conventional back electromotive voltage control method, in order to detect the stripping speed, the stripping speed must be set to the lowest possible value with less slip on the strip and with as little detection error as possible. It can be determined by detecting the rotational speed of the rolling roll, which is thought to reflect [.

However, the actual stripping speed varies depending on the rolling reduction rate, friction coefficient, material, etc. (equivalent to the advance rate in the winder and the backward rate in the unwinder), and especially in strip tension control. Large tension disturbances occurred during transient conditions such as acceleration and deceleration.

The present invention has been made by focusing on these conventional problems, and enables more accurate tension control of the strip by accurately detecting the strip speed and controlling the original back electromotive force. Its purpose is to write.

The present invention provides a strip tension control method using a back electromotive voltage control method, in which a back electromotive voltage signal is obtained from an armature terminal voltage signal of a DC motor and an armature resistance voltage drop signal, and a rotational speed signal of a rolling roll is obtained. is multiplied by an advance rate or a backward rate determined by the rolling reduction rate and strip tension, etc. to obtain a strip speed signal, and the DC motor is controlled so that the strip speed fg and the back electromotive voltage signal maintain a proportional relationship. The above object is achieved by controlling the field current of the strip to maintain a constant strip tension.

Embodiments of the present invention will be described in detail below based on the drawings.

FIG. 1 shows an example of a strip tension control device in which an embodiment of the method of the present invention is adopted.

The strip 14 leaving the rolling roll 12 of the rolling mill 10 is
It is wound up at a speed V by a winding machine 16.

The DC motor 18 that drives the winder 16 is current-controlled, and the armature current 1a is maintained at a predetermined value -C.

Note that 201 is an Iristor power supply device.

Here, the back electromotive force Ea is based on the above-mentioned equation (3). That is, first, the armature terminal voltage V at the terminal of the parallel resistor 22
The armature current Ia is detected at the terminal of the series resistor (or shunt resistor) 24. And this armature current 1a
is multiplied by the armature's internal resistance R in the multiplier 26 to obtain the armature resistance voltage drop IaR, and both voltage signals V and Ia
The adder 28 adds R and calculates V-IaR to calculate the back electromotive force Ea.

On the other hand, the strip speed V is determined as follows. That is,
First, a pulse generator (PLO) 30 generates a pulse corresponding to the rotational speed of the rolling roll 12, and a pulse counter 32
After performing appropriate digital/analog conversion, this is referred to as a voltage signal vr. Next, an advanced rate setter 34 multiplies this rotational speed signal vr by a predetermined advanced rate set value fs in a multiplier 37. This advanced rate setting value fs is
For example, 31 and F o as shown in the following formula
It can be calculated from an approximate expression of the expression of rd.

[: Advance ratio T: Reduction ratio μ: Friction coefficient h: Output side plate thickness (mm) R' double flat roll diameter (made) [f: Front tension (kg/■a) Lb: Backward tension (kg/■ ()) Kp: Deformation resistance (kg/i()) Strip tension control is performed as follows.First, measure the appropriate ratio of each signal corresponding to the back electromotive force Ea obtained above and the strip speed. Multiplier 3 for minutes
6.38, and the adder 40 joins the two together. When the stripping speed v and the tension F are stable, the deviation ε=O is input to the back electromotive force control device 42, and a predetermined field current Field of DC electric VA18 from thyristor power supply 46
The signal is controlled so that it flows to the file 48.

Now, for example, when the strip speed ■ becomes faster.

The strip 14 becomes loose and the tension is reduced. This poetic method works. First, since the signal side of the stripping speed ■ becomes large, a deviation ε occurs in the matching at the adder 40. The back electromotive voltage controller @42 increases the field current lf supplied from the field thyristor power supply 46 to the field coil 48 via the field current controller 44 so as to eliminate the deviation ε. . As a result, in the relationship of equation (2) above,
Since the armature current 1a is current-controlled, the magnetic flux φ increases in accordance with the increase in the field 11 current If to the field coil 48, and the back electromotive force Ea increases, so that Ea/V always maintains a proportional relationship. This will result in feedback. As long as this Ea/v maintains a proportional relationship, the strip tension F is controlled to a constant value according to the armature current 1a based on the relationship of equation (11).

In this embodiment, the processing of various calculations is done in analog, but it is possible to do it digitally. It is ideal to actually measure and detect online, but
Since each calculation element is considered to be almost constant, considering that the advanced rate setting value is originally for correction, it is only necessary to set it as a variable before each rolling schedule. There is no need to actually measure online.

It goes without saying that when the present invention is applied to the rewinding side, the backward rate is used instead of the forward rate.

As described above, according to the present invention, the strip speed can be determined extremely accurately, and the strip tension can be accurately controlled based on the original back electromotive force control.

[Brief explanation of drawings]

FIG. 1 is a block diagram including a partially schematic sectional view showing a strip tension control device based on a back electromotive force control method, in which an embodiment of the method of the present invention is adopted. F (kg)... Winding tension (-strip tension), rm
<Tsum・m)...Torque generated by a DC motor, ■(vo
lt)... Armature terminal voltage, Ia (A)... Armature current, 1aR ('vo 口)... Armature resistance voltage drop, y (
m/sec)...Strip speed, V I" (
VOlt)... Voltage signal equivalent to the rotational speed of the rolling roll, 12... Rolling roll, 14... Strip, 16... Winding machine, 18... DC motor, 34... Advanced rate setting equipment, fs...Advanced rate setting value. Agent Takaya Ron (and 1 other person)

Claims (1)

[Claims] (1) By maintaining a proportional relationship between the speed of the strip and the back electromotive force in the DC motor that drives the winder for winding or unwinding the strip, the tension of the strip can be increased. In the method of controlling the strip tension to maintain constant the voltage, a back electromotive force signal is obtained from the armature terminal voltage signal of the DC motor and the armature resistance voltage drop signal, and the rotational speed signal of the rolling roll is and a forward rate or a reverse rate determined by the strip tension, etc. to obtain a strip speed signal, and control the field current of the DC motor so that the strip speed signal and the back electromotive voltage signal maintain a proportional relationship. A strip tension control method characterized by maintaining the strip tension constant.