US2715959A - Multiblock wire-drawing apparatus and method - Google Patents

Description

Aug. 23, 1955 w. E. ZELLEY 2,715,959

MULTIBLOCK WIREDRAWING APPARATUS AND METHOD Filed Feb. 17, 1951 2 Sheets-Sheet 1 FIGJ INVENTOR. WILLIA M E. ZELLEY QCQQW ATTORNEY.

Unite rates Patent nice bud

MULTIBLOCK WIRE-DRAWING APPARATUS AND METHOD William Elwood Zelley, Columbus, N. 3., assignor, by

mesne assignments, to John A. Roeblings Sons Corporation, Trenton, N. J., a corporation of Delaware Application February 17, 1951, Serial No. 211,523

3 Claims. (Cl. 205-44) This invention relates to continuous wire-drawing machinery and to problems peculiar to that art. it is particularly concerned with machines of the type having a series of dies through which the wire stock is drawn by rotating blocks or drums to effect successive reductions of the stock into wire of desired diameter.

Continuous wire-drawing machines have long been known wherein the blocks (except the final one) are driven faster than the wire so that they act as slipping capstans, with only a minor amount of tension (or back pull) on the wire entering the dies. The tension or back pull on the wire going from a block or capstan to the next die depends upon the number of wraps of wire around the capstan and can be made quite small.

Other continuous wire-drawing machines are available which drive the blocks without slip, pulling the wire from the preceding die at high tension and delivering it to the next die at low tension, sufiicient only to prevent slip on the block. Since slip does not take place, many more turns of wire may be put on the block, sufiicient to provide cooling of the wire between the dies. To assist cooling, the blocks may be water-cooled and/or.air cooled, and the dies may also be water cooled. The speed possibilities of the machine depend in some measure upon the need for cooling the wire between the dies.

Another type of continuous wire-drawing machine operates the block-motors (except the motor for the final block) at torques sufiiciently low that all of the blocks except the last one try to run slower than the wire. However, the capstan effect of the blocks prevents them from slipping and they are partially driven by the substantial pull on the wire between the block and the next die ahead (i. e., back pull). it has been established that wire drawing with substantial back pull has certain advantages, the principal ones of which are reduction in friction between the die and the wire resulting in less generation of heat, reduction in power required, and longer die life.

An important feature of the present invention is the provision of a continuous wire-drawing apparatus having means for rotating certain of the blocks faster than the wire to provide slippage therebetween, or to rotate the blocks at substantially the speed of the wire without slippage, or to operate the blocks to provide substantial back-pull or tension on the outgoing wire. So far as I am aware, I am the first to provide for the attainment of these three modes of operation at the option of the attendant in a single wire-drawing machine.

My invention further provides marked advantages with respect to each of the aforementioned modes of operation.

In conventional machines which provide for slippage between the capstans and the wire, the capstans are driven at speeds which increase in successive blocks at a fixed ratio. For example, a machine may be made so that the block speed increases correspond with a length increase which occurs when wire is reduced in area 15% per die. Such a machine is suitable for use where the reductions in area per hole exceed 15% but will break the wire if the reduction in area is less than 15%. In practice, in order to allow for normal variation and wear in die sizes, such a machine would be used for 20% reduction in area per hole. Since the slip is cumulative, excessive slip occurs on the first few blocks. In cases where ten or more blocks are used it is common for such slip to exceed 106%. T his causes excessive wear of the blocks and generates excessive heat, usually requiring external liquid cooling of the blocks (so called wet drawing). With the present invention each block may be adjusted to a minimum of slip, no matter what the reduction in area of the wire may be at each die. This arrangement permits slipping without excessive heating or wear and makes it possible to draw without external liquid cooling of the blocks if so desired.

Conventional machines for use without slip frequently have a jockey pulley between the blocks and the succeeding dies, movement of which is used to control the block speed in order to prevent slip. Such an arrangement has disadvantages for drawing at very high speeds because of hunting of the jockey pulleys. Also it is not suitable for very heavy material such as copper or bronze trolley wire which is so stiff that it cannot be bent conveniently around jockey pulleys.

In the present invention there are no jockey pulleys. The wire passes directly without bending from the block to the die, to the next block. The invention is therefore suitable for drawing heavy material or for drawing lighter material at high speeds.

A machine now on the market for drawing with back pull has the motor armatures in series and as a result, acts somewhat like a differential gear in that if one block becomes unloaded for any reason, the motor will speed up and run away. 0verspeed protection is provided to prevent the motor from bursting from centrifugal forces. Such running away occurs if the wire breaks or if the back pull is reduced to a point where the block can slip.

With the invention here described the motors do not run away when the wire breaks and the back pull may be reduced any amount, accidentally or otherwise, without danger of the motors running away.

Furthermore, with this invention great flexibility of wire drawing is possible. For example, any desirable reduction of area of the wire may be obtained at any die and at the same time the machine may be adjusted for slipping blocks, non-slipping blocks without much back pull, or for non-slipping blocks with substantial back pull, as may be desired. Also the machine is provided with indicating instruments which show the mode of operation being used.

A further advantageous feature of my invention resides in provisions for controlling the spooler so that it may receive wire from any of the wire-drawing blocks.

Other features and advantages of the invention will be hereinafter described and claimed.

in the accompanying drawings:

Fig. 1 is a diagrammatic plan view of a continuous wire-drawing apparatus having four dies and four blocks, together with a spooler, operable in accordance with my mvention.

Fig. 2 is a wiring diagram illustrative of electrical connections suitable for carrying out the invention.

Referring to Fig. 1, the wire 1 passes from a conventional pay-off device, such as a swift (not shown) through the first die 2 to the first block or capstan 3, thence through the second die 4 to the second capstan 5, through the third die 6 t0 the third capstan 7, and then through the fourth die 8 to the fourth capstan 9. It then passes through the customary fleeting guides 10 to the take up spool 11. The capstans may be water and/or air cooled and the dies may be Water cooled, if desired, as in prior practice.

Motors 12, 13, 14, i5, and i6 drive the respective capstans and take-up spool through conventional speed reducing gearing R7, l3, i9, 26 and 21 respectively. The fleeting guides 16 are driven through reducing and reversing gears of conventional design (not shown) arranged to traverse the wire back and forth across the spool in the usual manner.

Turning now to Fig. 2, it will be noted that power is supplied to the various motor armatures by a motorgenerator set comprising a motor 25 and a generator 26. An eXciter 27 also driven by motor 2'5 supplies current to the field 28 of said generator. The amount of current in said field is controlled by an adjustable resistance 29, which is part of a gang rheostat for con.- trolling the speed of wire drawing. The exciter is shown provided with a series field 30 and a shunt field 31, the latter being controlled through an adjustable resistance 32.

The armatures of the respective block motors 12, 13, 14, and 15 are connected in parallel across the mains 33 and 34 supplied with current from the armature of generator 26. For convenience in reading the drawings said armatures are also designated in Fig. 2 as the No. 1 Block Motor, No. 2 Block Motor, No. 3 Block Motor, and No. 4 Block Motor, respectively. Said motors are provided with series fields 35, 36, 37, and 33, and also with fields 39, 41, and 42, the latter fields being connected across the leads 43 and 44 supplied with current from the armature of the exciter 27. Thus each of said motors has compound field windings, and these windin s (i. e., the series winding and the winding across the exciter mains) are cumulative in their action. in other words, they reinforce each other, so that moderate changes in speed result from changes in torque or load.

The current through the field windings 39, 40, 41, and 42, respectively, may be varied by adjustment of the corresponding resistances 45, 46, 4-7, and 48 in series therewith. Also in series with said windings 39, 4d, 41, and 42 and with the corresponding resistances 45, 46, 47, and 4%, are other resistances 49, 5t), 51, and 52, respectively, which form parts of the aforementioned gang rheostat.

During threading up of the machine, the blocks are operated at slow speeds, and the speed of each block motor is individually adjusted by varying the associated field resistances 45, 46, 47, or 48. After said resistances have been suitably adjusted individually for slow speed, the speeds of the block motors are increased by rotating the gang rheostat, which may be of any suitable or conventional type. Rotation of the gang rheostat first decreases the resistance 29 in circuit with field 28, bringing the generator 2-6 up to full voltage and thereby bringing the block motors up to base speed. It then increases the resistances 49, 5%, 51, and 52 in circuit with the fields 39, 40, i1, and 42 of the block motors, weakening said fields and thereby further increasing the speeds of said motors.

The torques exerted by the wire drawing blocks are indicated by torque meters 54-, 55, 56, and 57, each comprising an instrument of the dynamorneter type having relatively movable coils, one connected across a fixed resistance shunt which is in series with the armature of a block motor and the other connected across the corresponding motor field windings 39, 4t), 41, or 42. The readings of each torque meter are proportional to the product of the armature and field currents, which in turn are approximately proportional to the torque developed by the associated block motor.

In addition, each of the block motors drives a corresponding one of a plurality of tachometer generators 58, 59, 6t), and 61 supplying current to speed-indicating meters 62, 63, 64, and 65, respectively. The latter may be of conventional type and may be calibrated to show the surface speed of the blocks in feet per minute.

In Fig. l the spooler 11 is shown as receiving wire from the fourth block of the series, i. e., the block designated 9. If, however, less than four blocks are to be used, the spooler receives the wire from whichever block is the final one of the series. In that connection I have provided for the control of the speed of the spooler motor 16 by whichever one of the blocks is selected as the final one.

The spooler motor armature is shown connected across mains 67 and 68, which are supplied with current from the generator 79 of a motor-generator set 69, 70. Said spooler motor has a series field 71, and also a field 72 supplied with current from generator 74 of another motor-generator set 73, 74.

The generator 70, which furnishes current to the spooler motor armature, has a series field 75 and also a field 76 in circuit with a variable resistance 76. Said I field 76 receives current from a generator 78 of a motor-generator set 77, 78.

The generator 78 is provided with three fields, designated 79, Si and 81, respectively. Field 79 is in series with the armature of said generator. Field 80, termed a pattern field is connected to a selector switch arm 82 adapted to be manually shifted into engagement with any of four contacts at the ends of wires 83, 84, 35, and 86 each connected to a corresponding one of the tachometer generators 58, 59, 60, and 61. The opposite terminal of said field is connected to a wire 87 which forms a common return from said tachometer generators. It will thus be apparent that through the selector switch arm 82 the pattern field 80 of generator 78 may be connected to any desired one of the tachometer generators aforementioned.

The field 81 of generators '78, termed a pilot field, is connected across the mains 67 and 68 supplied by generator 70, and is in series with an adjustable resistor 88. Said field 81 is wound so as to oppose the pattern field winding 80. The voltage of the tachometer generator to which said pattern field winding is connected is thus compared with the voltage supplied by generator 70. Since the voltage of said tachometer generator is proportional to the speed of the block motor which drives said generator, the speed of said block motor is compared with the voltage output of the generator 70 which is impressed upon the spooler motor armature and its series field 71. Variations in the speed of said block motor thus produce variations in voltage supplied by the generator 78, and corresponding variations in current through the field winding 76 of generator 70. The voltage impressed by the latter upon the spooler motor armature and its series field 71 is thus varied in accordance with variations in speed of the block motor, to vary correspondingly the speed of said spooler motor. In short, by this arrangement the field 76 of generator 70 is varied so that the pilot field 81 of generator 78 matches the pattern field 80 at all times and thereby the speed of the spooler motoris caused to correspond with that of the finishing block selected by the switch 82.

The generator 74 controls the tension applied by the spooler motor. To that end the pilot field 90 of said generator 74 is connected across a resistance 91 in series with the armature of the spooler motor, so as to respond to the current through said armature. The pattern field 92 is connected across the mains 43, 44 supplied by the exciter 27, and may be set manually to a desired value by adjustment of a resistance 93. The series field 94 is energized by said generator 74 and may be manually adjusted by varying the resistance 95. Said field 94 is also in series with the spooler motor field 72.

As the spool fills, the torque of the spooler motor is increased to maintain constant tension. This is accomplished by measuring the armature current through the pilot field 9i), and matching it against the pattern field 92, which is wound to oppose the pilot field winding.

r, Variation in the armature current is thus reflected in variation of output of the generator 74 and thus in current through the field 72 of the spooler motor, which in turn acts to restore the armature current to its previ ous value. In other words, the field 72 of the spooler motor is varied to maintain a match between the pilot and pattern fields of generator 74 and thereby to maintain substantially constant the current through the armature of the spooler motor. By maintaining said current substantially constant, the spooler motor is caused to deliver substantially constant horsepower, and thus to maintain substantially constant tension in the wire, as the spools fills up. The spooling tension may be adjusted by changing the pattern field 92 through manual adjustment of the resistance 93. Said tension is indicated by the watt meter 96, one coil of which measures the current through the armature of the spooler motor and the other of which measures the voltage applied to said motor by the generator 70.

When it is desired to operate the machine with slippage between the wire and the first three blocks and only minor back pull, the block- speed controlling rheostats 45, 46, and 47 are manually adjusted to increase the speed of said blocks until they are travelling faster than the wire. This condition may be observed, and the amount of it determined, from observation of the meters 62, 63, and 64. It may also be seen by observing the curvature of the wire coming off a block and going into the next die. Because of the natural curvature of the wire and the low tension or back pull during slipping operation, noticeable curvature is present. The blocks act as capstans; and the amount of back pull (pull between a block and the next die) is determined by the number of wraps on the blocks, and can be made quite small.

When operation with no slippage on the blocks, and

minor back pull, is desired, the aforementioned resistances 45, 46, and 47 are adjusted to reduce the speed of said blocks until they just reach the point of no slippage. This condition may be readily ascertained by observing the torque meters as the speed is reduced. So long as the blocks are slipping the torque is constant, but as soon as the speed is reduced below the slipping point the torques decrease because some of the pull for the wire drawing is supplied as back pull. Thus, for this condition of operation the blocks are run as slowly as possible without causing a decrease in torque. The finishing block is, of course, run at the required finishing speed; and the spooler tension adjusted sufiiciently high to prevent slipping on this block. The finishing block should not show an increase in torque as the other blocks are slowed.

It may be noted that as the condition of no-slippage operation with minor back pull is reached, the curvature of the wire between a block and the next die is reduced slightly but is still present.

To obtain the third condition, i. e., no slippage on the blocks and major controlled back pull, the speeds of the blocks (other than the finishing block) are further reduced. This condition is shown by the disappearance of the curvature in the wire. It is also shown on the aforementioned meters 62, 63, and 64, which fail to show a reduction in speed in spite of the fact that the resistances 45, 46, and 47 are moved to reduce speed (provided that the finishing block is maintained at constant speed). Under this condition the tension supplied by the finishing block drives the preceding block motors faster than they would otherwise run.

This third condition above mentioned may also be observed from the torque meters; since the torques of all blocks except the finishing block are reduced, and the torque of the finishing block is increased to compensate for the reduction of the others. The change in torques is due to back pull between blocks and the succeeding dies and may be used to measure and control the amount of back pull.

Among further advantages presented by the embodiment of my invention herein disclosed, it may be noted that by providing a separately excited field for the generator 26, said field is not subject to variations in generator current supplied to the motors. Also, by having the block motor fields 39, 40, 41, and 42 excited separately from the generator 26 which supplies current to the motor armatures, said fields are not subject to fluctuation by variations in said generator current during variations in the speeds of said motors.

The terms and expressions which I have employed are used as terms of description and not of limitation, and I have no intention, in the use of such terms and expressions, of excluding any equivalents of the features shown and described or portions thereof, but recognize that various modifications are possible within the scope of the invention claimed.

I claim:

1. A multiple-die wire-drawing machine comprising a plurality of dies and pulling blocks alternately arranged so that the wire passes directly from a die to its pulling block and thence directly to the next die, separate electrical motors for driving said blocks without variation in wire storage during wire drawing, the armatures of said motors being connected in parallel across a first electrical power supply and the shunt field windings of said motors being connected in parallel across a second electrical power supply, means for varying field resistances of all of said motors concurrently to vary the motor and block speeds in substantial unison, means for varying field resistances of said motors individually to vary the speeds of the respective motors thereby selectively to operate the corresponding blocks faster than the wire to provide slippage between the blocks and the wire, to operate the blocks at substantially the speed of the wire without slippage or to operate the blocks with a selected tension on the outgoing wire, and means for determining the operating condition of said blocks comprising an individual speed indicating means for each of said blocks and individual means for indicating the torque imparted to said blocks by said motors.

2. A multiple-die wire-drawing machine comprising a plurality of dies and pulling blocks alternately arranged so that the wire passes directly from a die to its pulling block and thence directly to the next die, a first generator providing a source of electrical power supply, a second generator providing a second source of electrical power supply, said first generator having a field winding connected across said second electrical power supply, separate electrical motors for driving said blocks without variation in wire storage during wire drawing, the armatures of said motors being connected in parallel across said first electrical power supply and the shunt field windings of said motors being connected in parallel across said second electrical power supply, means comprising a gang rheostat operable first to vary the resistance of said generator field and then to vary the resistances of said motor fields in substantial unison with each other thereby to vary the motor and block speeds in substantial unison, and means for varying field resistances of said motors individually to vary the speeds of the respective motors thereby selectively to operate the corresponding blocks faster than the wire to provide slippage between the blocks and the wire, to operate the blocks at substantially the speed of the wire without slippage or to operate the blocks with a selected tension on the outgoing wire.

3. A multiple-die wire-drawing machine comprising a series of dies and pulling blocks alternately arranged so that the wire passes directly from a die to its pulling block and thence directly to the next die, separate electrical motors for driving said blocks without variation in. wire storage during wire drawing, the armatures of said motors being connected in parallel across a first electrical power supply and the shunt field windings of said motors being connected in parallel across a second electrical power supply, means for varying field resistances of all of said motors concurrently to vary the motor and block speeds in substantial unison, means for varying field resistances of said motors individually to vary the speeds of the respective motors thereby selectively to operate the corresponding blocks faster than the wire to provide slippage between the blocks and the wire, to operate the blocks at substantially the speed of the wire without slippage or to operate the blocks with a selected tension on the outgoing wire, a spooler for receiving wire from the final block of the series, a motor for driving said spooler, speed-responsive means for controlling the speed of the speoler motor, means for maintaining the horsepower of the spooler substantially constant to maintain substantially constant tension in the wire passing on to said spooler, and means for selectively placing said it speed-responsive means under the control of any one of a plurality of the block motors.

References Cited in the file of this patent UNITED STATES PATENTS 1,281,439 Vicaire Oct. 15, 1918 1,916,447 Stokes July 4, 1933 1,930,246 Long Oct. 10, 1933 2,185,416 Morgan et al. Jan. 2, 1940 2,237,112 Parvin Apr. 1, 1941 2,242,435 Parvin May 20, 1941 2,315,869 Montgomery Apr. 6, 1943 2,557,215 Bruestle June 19, 1951 2,567,635 Bundy Sept. 11, 1951

Images