US3822575A

US3822575A - Non-slip non-accumulating continuous wire drawing machine

Info

Publication number: US3822575A
Application number: US00271724A
Authority: US
Inventors: L Hoorelbeke
Original assignee: Bekaert NV SA
Current assignee: Bekaert NV SA
Priority date: 1971-07-16
Filing date: 1972-07-14
Publication date: 1974-07-09
Anticipated expiration: 1991-07-09
Also published as: FR2146285B1; NL7209669A; ES404871A1; BE770100A; FR2146285A1; IT965912B; GB1400176A

Abstract

A wire drawing machine has a plurality of drawing dies each associated with a drawing block powered by a direct current electric motor, all the motors being connected in parallel and having current supply controlling circuitry which insures that the sum of all of the motor speeds are constant and that all torques are equal except for a proportionality factor.

Description

United States Patent Hoorelbeke [451 July 9, 1974 1 NON-SLIP NON-ACCUMULATING CONTINUOUS WIRE DRAWING MACHINE Inventor: Luc Hoorelbeke, Kortrijk, Belgium Assignee: N. V. Bekaert S.A., Zwevegem,

Belgium Filed: July 14, 1972 Appl. No.2 271,724

[30] Foreign Application Priority Data July 16, 1971 Belgium 770100 US. Cl 72/288, 72/289, 72/19 int. Cl. B2lc 1/12 Field of Search 72/19, 29, 279, 280, 288,

References Cited UNITED STATES PATENTS Vicaire 72/2 88 1,914,833 6/ 1 933 Nacken 2,124,518 7/1938 Marquart.... 2,321,612 6/1943 Nye 2,708,024 5/1955 Bryden 2,759,139 8/1956 Few 3,518,859 7/1970 Brinkeborn 3,586,221 6/197 1 Rosen 226/1 Primary Examiner-Charles W. Lanham Assistant ExaminerM. J. Keenan Attorney, Agent, or FirmShlesinger, Arkwright, Garvey & Dinsmore 1 ABSTRACT A wire drawing machine has a plurality of drawing dies each associated with a drawing block powered by a direct current electric motor, all the motors being connected in parallel and having current supply controlling circuitry which insures that the sum of all of the motor speeds are constant and that all torques are equal except for a proportionality factor 4 Claims, 1 Drawing Figure ws Win S5 [Sn This invention relates to a non-slip non-accumulating continuous wire drawing machine with adjustable back-pull containing a number of drawing dies and drawing blocks, whereby each drawing block is driven by a direct current motor with external excitation and whereby the interconnection of the motors and the design of the control mechanism are such that the sum of the speeds of all motors remains constant and that, except for a proportionality factor, the torques connected to the motors remain equal to each other. Nonaccumulating means that the wire is not pulled over transfer pulleys between the successive blocks in order to carry out speed regulations.

This invention also relates to other kinds of machines, such as hot and cold rolling mills, and so on b. the torques remain equal to each other except for a proportionality factor: Q C, r C2 l c,.=k,.c.

.Since externally'excited current motors are used for driving the various blocks of the wire drawing machine, and takinginto account the basic equation of the externally excited direct current motor, equations (1) and (2) may also be expressed as follows basic equation of direct current motor:

"I l 1 1a 2 2/ 2 2 "n ll Il (I) where U, U,, are the terminal voltages of the motors m I D are the fluxes generated by the field windings of the motors m m,, k, k are constants. KICDIII C2 2 2 2 u n n n ("l n constant In order to obtain the above-mentioned advantages, viz, automatic compensation, or to obtain a differential wire drawing machine, equations l and (2) must always be met. Asimilar wire drawing machine for which equations (1') and (2) are always met, is known, viz, a wire drawing machine with series-connected driving motors m, m, m,,, such as described in theBelgian Pat. No. 481.842.

However, this known machine has important disadvantages, viz,:

In case of wire breakageduring the drawing process, threading-up is accomplished, after welding the wire, by an appropriate change of the torques acting on the motors. This change is effected by altering the field current in the field windings of these motors. So, the torques connected to each motor for a certainstationary regime must be changed and readjusted in order to reobtain the stationary regime. This is a complicated and time-absorbing process.

In the case of series-connected drivingmotors, it is necessary to use special transformers for the classic motors (440 volts), and to develop special low tension motors; this is the most used solution.

In addition, since the current in series-connected moto'rs is very high, the lives of the motors is prejudiciallyinfluenced'. Indeed, the necessary power P U]. As U is generally low, a high current I is used.

The danger of racing of the motors in case of wire breakage is also a disadvantage. In case of breakage'all motors stop, whereas one of the motors starts racing. In stationary regime, the total applied voltage U is distributed over the motors or a volt age U/n is applied to each motor.

Because all motors stop except one, the latter will try to reach such a speed that its E.M.F. is equal to the totalvoltage U or, in other words, this motor will try to runn times faster.

In the case of series fed motors, it is necessary to stretch the wire between the successive blocks so that the machine may start again after having been stopped when the wire hung loose or sagged between the successive'blocks. This happens by a change of the torques acting on the motors. This change is effected by altering the field current in the field windings. Also this is a complicated and time-absorbing process.

Working with less passes than normally provided for the machine also entails important difficulties. For example, a principal n-hole machine from which three passes are eliminated. In case of series feed, each motor to be eliminated must be bridged by means of a contactor which must be able to deviate the large series current.

It is an object of the invention to provide a wire drawing machine of the aforesaid type wherein also equations (1") and (2) are always met and, moreover, wherein the aforesaid disadvantages of the known machines are eliminated.

' Therefore, it is proposed that for a wire drawing machine of the aforesaid type, these direct current motors m, m, are connected in parallel, whereby each motor m m,, is provided with a self-controlled rectifier G G for converting the feed from the al' temating current system, so that each motor m m is provided with a direct voltage output circuit 0 a m, up to m,- in position III, all motors m,,t,

0,, for the separation of the terminal voltages U U,,, whereby the output terminals of these transformers O, 0,, are connected in series for summing up or obtaining EU, and that the regulating mechanism of the assembly is provided with an adjustable direct current source U for the determination of a reference voltage U and, furthermore, with an amplifier P, whereby the input of the amplifier is determined by the difference U EU, and the output of this amplifier is transferred to the control circuit of the rectifiers G, (7,, or is used as reference value I, for the determination of the currents I, I,,. i

The regulating mechanism of a wire drawing machine according to the invention, of which the motors m, m,, are connected in parallel, is designed in such a way that when making a correction in order to meet equation l or EU, constant, equation (2') is automatically met, or, in other words, in order to meet EU, constant (-1 a correction is made by changing the currents I, I 1,, in the motors m, I m,, in such a way that equations (2) are always met. This is obtained by taking the output value of amplifier P as a reference value for the determination of currents], 1,, in the motors m, m,,, or, in other words, this signifies that the control circuits of the rectifiers G, G,, are connected in parallel'on the output of amplifier P.

In a wire drawing machine according to the invention, a switch S S,, is provided between the output of amplifier P and the input of each control circuit of the rectifiers of the motors, and the control mechanism of each motor m, m,, isprovided with a handle H, H,, having four positions, I (up), II (down), Ill (left), and IV (right), whereby these switches S, S,, and this handles H, H,, are mutually connected by means of known relay connections in such a manner that for any motor m,, only motor m, is energized in position I, all motors m, m,, in position II, all motors p to m,, in position IV, and that, when released, each handle H, automatically takes the zero position.

A wire drawing machine as set forth in the invention offers the following advantages:

When wire breakage occurs, wire threading after welding can be done by connecting only the motors that serve for carrying out this operation, since the control circuit of each motor can be easily interruptcd. This happens by moving the handles H, H,, or in other words by controlling the switches S, S,,. The torques C, C,, acting on these motors are no longer altered by a change of the cur rent in the field windings. This considerably simplifies the service of the machine.

Because of the parallel feed of the motors, the threephase alternating current system (380 volts) can be used without using transformers for the classic direct current motors (440 volts).

The parallel feed of the motors also pennits maintaining the current in each motor at a low level, which is of importance for a long motor life.

In case of wire breakage, there is no danger for racing of the motors. A classic motor (440 volts) will maximally run percent above its normal working "speed, since the applied voltage can maximally be 510 volts in a three-phase alternating current system of 380 volts.

Since each motor m, m,, has a proper current control with its own time constant, the machine according to the invention may run in with somewhat loose wires on various blocks. This saves time and difiiculties when starting.

Working with a smaller number of passes than normally provided for the machine does not entail any difficulties. It is only necessary to interrupt the control circuit of the motors 'or blocks to be isolated.

The invention will now be described in greater detail, with reference to the accompanying drawing, the single FIGURE of which is a circuit diagram of the machine as set forth in the invention.

The machine illustrated in the drawing is a non-slip non-accumulating continuous wire drawing machine with adjustable back-pull containing n drawing dies T,

...T,-. .T andndrawingblocksW, ..W,-...W,,. Each block W, W,- W,, is driven by a separate direct current motor m, m, m,, with external excitation. These motors m, m,, are connected in parallel. The nominal voltage of these motors is for example 440 volts. Each motor m, m,, is provided with a self-controlled rectifier G, G,, for converting the feed from the three-phase alternating current system, for example an alternating voltage of 380 volts. The rectifiers G, G,, are controlled by means of a thyristor circuit. It is assumed that for a certain stationary regime, the motors m, in, m,, should produce torques C,.. .C, C,, at speeds n, n,- n,,. Except for a proportionality factor, these torques are determined by the product of the fluxes I 1 4 produced by the field windings P, P, P,, and the armature currents I, I, 1,, or C, =k,l ,1, ..C,-

=k, I ,-I,- and C,, =k,, I ,,I,,. The fluxes I 1 CI in the field windings P, P, P,, are determined by using the resistors R, R, R,, of these windings and the armature currents I, I, 1,, in the motors by current amplification of the adjustment.

Each motor m, m,, is provided with a direct tension direct tension transformer O, 0,, for the galvanic separation of the terminal voltages U, U,,-of the motors, whereby the output clamps of these rectifiers O, 0,, are series-connected, so that except for a proportionality factor, the sum or 2U, tained.

The regulating mechanism of the machine is provided with an adjustable direct tension source U for the determination of a reference tension U which corresponds to a certain sum of the speeds n, n, ...+n,,or2U,

Furthermore, the control mechanism is provided with an error amplifier P, whereby the input value of the amplifier is determined by the difference U EU, and the output value of this amplifier is transferred to the control circuit of the rectifiers G, G,,. This means that the output value of the amplifier P is used as reference value 1,, for the, determination of currents I, I, 1,, in the motors.

Switches S, S,- S,, are provided between the output of amplifier P and the input of each control circuit of the motors. Moreover, each motor m, m, m,, is provided with a handle H, H,- H, having four positions, I(up), II(down), III(left), IV(right). The switches S, S,, and these handles I-I, H, are connected by means of known relay connections in such a way that for any motor m,- only motor m, is energized in position I, all motors m, m,, in position II, all motors m, up to m,- in position III, and all motors m,,, up

to m in position IV. When released, each handle H,- automatically takes the zero position, or, in other words, the associated switch S,- is automatically opened.

f. power supply means for supplying electrical energy to each of the electrical motors and to which they are connected in parallel,

g. the power supplymeans having a variable electrical output which is dependent upon a control voltage supplied thereto,

h. the total speed output signal of the summing means being applied to the power supply means as a control voltage to control the electrical energy output to the electrical motors. 2. The plural stage processing assembly as set forth in claim 1, wherein:

tween switches S S and the associated handles Hi H in order to obtain other controls from switches S S in other handle positions.

What we claim is:

l. A plural stage processing assembly for a length of metal, comprising;

a. a plurality of metal deforming stations through which a length of metal is successively passed,

b. takeup and drawing means at each deforming station and in engagement with the length of metal,

c. a separate electrical driving motor connected to each of the takeup and drawing means,

(1. motor speed measuring meas connected to each motor for measuring the speed thereof and producing an output signal dependent on motor speed,

e. summing means to which the outputs of all of the motor speed measuring means are interconnected for producing a total motor speed signal representing the sum of all of the output motor signals,

a. the power supply means is an amplifier through which alternating current is supplied,

b. each of the electrical motors is a direct current motor,

c. each of the motors has a self-controlled rectifier means connected between the source and the motor.

3. The plural stage processing assembly as set forth in claim 1, wherein:

a. each metal deforming station is a wire drawing die,

h. each of the takeup and drawing means is a drawing block. 4. The plural stage processing assembly as set forth in claim 1, wherein:

a. automatic switch means is provided in each of the motor circuits for either energizing or deenergizing the motor.

Claims

1. A plural stage processing assembly for a length of metal, comprising: a. a plurality of metal deforming stations through which a length of metal is successively passed, b. takeup and drawing means at each deforming station and in engagement with the length of metal, c. a separate electrical driving motor connected to each of the takeup and drawing means, d. motor speed measuring meas connected to each motor for measuring the speed thereof and producing an output signal dependent on motor speed, e. summing means to which the outputs of all of the motor speed measuring means are interconnected for producing a total motor speed signal representing the sum of all of the output motor signals, f. power supply means for supplying electrical energy to each of the electrical motors and to which they are connected in parallel, g. the power supply means having a variable electrical output which is dependent upon a control voltage supplied thereto, h. the total speed output signal of the summing means being applied to the power supply means as a control voltage to control the electrical energy output to the electrical motors.

2. The plural stage processing assembly as set forth in claim 1, wherein: a. the power supply means is an amplifier through which alternating current is supplied, b. each of the electrical motors is a direct current motor, c. each of the motors has a self-controlled rectifier means connected between the source and the motor.

3. The plural stage processing assembly as set forth in claim 1, wherein: a. each metal deforming station is a wire drawing die, b. each of the takeup and drawing means is a drawing block.

4. The plural stage processing assembly as set forth in claim 1, wherein: a. automatic switch means is provided in each of the motor circuits for either energizing or de-energizing the motor.