GB2104555A - Wire tension apparatus - Google Patents

Abstract

Wire is dereeled at high speeds through a tension assembly (44) having a pair of friction pads (46) between which the wire passes. The clamping pressure applied to the friction pads (46) is controlled by adjustable clamp means (48, 52, 66). The wire then extends around a pulley (70) and through a tensioner (94) including a pair of spaced, fixed eyelets (100, 102) and an eyelet (104) on the end of a lightweight dancer arm (106) surrounding the wire spanning between the fixed eyelets to take up slack wire. Adjustable bias means (124) is applied to the dancer arm to cause it to pull the wire out of a straight line path between the two fixed eyelets. Wire breakage is detected by monitoring the rotation of the pulley (70). <IMAGE>

Description

SPECIFICATION Wire tension and take-up apparatus This invention relates to wire tension and takeup apparatus especially adapted for use in armature-winding machines wherein fine wires are wound into coils at high speeds. The invention may also be used with other machines for winding coils including stator winding machines, and in general, wherever wire is unreeled in response to an uneven demand at high speeds.

Several types of unreeling or dereeling devices have been proposed and used. These devices are generally mounted closely adjacent to a spool of wire and are designed to exert some tension on the wire. They are also typically provided with some means for levelling out the tension depending upon the demands of the machine with which the wire is to be used. Available unreeling or dereeling devices may be satisfactorily used in a variety of applications. However, no entirely satisfactory dereeling device is available for use in very high speed winding of coils from fine wire for use in association with armature winding machines because of the rapidity with which the device must respond to varying wire demand during the winding of a coil and while commutator connections are being made between the winding of the coils.Problems associated with dereeling devices are especially severe in connection with the winding of armatures from fine wire which breaks easily due to the uneven tension placed thereon which may result in the wire becoming kinked or snarled or simply being placed under greater tension than the wire can withstand. The problems associated with winding such armatures are compounded by the typical need for winding a large number of turns for each coil. For example, it would not be uncommon to wind coils in excess of 1,500 turns using very fine wire, for example No. 40 gauge. Armatures of this type might be wound on double flier type armature winding machines with flier speeds in excess of 3,000 rpm.

Considering that the wire is guided into the armature slots by tooling which of necessity creates different wire demands as each coil turn is wound, there usually being two intervals of peak high wire demand and two intervals of peak low or no wire demand per turn, the dereeler device must be capable of responding to differences in wire demand at a rate in excess of 10,000 peaks per minute while a coil is being wound. The dereeler device must also be capable of responding to relatively large changes in wire demand during the intervals between the winding of coils in which the lead wire connections are formed.

In accordance with this invention, a wire tension and take-up apparatus is provided for use as a dereeler capable of handling very fine wire wound into coils at high speeds in armature winding machines. The apparatus of this invention is inexpensive to manufacture, simple and rugged in operation, and comprises a relatively simple wire tension assembly which includes a pair of friction pads so mounted that the wire is coursed therebetween and the pads frictionally resist movement of the wire. The pads have a relatively large surface area so that the wire is engaged therewith over a fairly substantial length. Clamp means are provided for urging the pads toward one another, the clamp means being adjustable so that the frictional forces acting on the wire may be adjusted.After initial adjustment of the clamping pressure for a particular winding operation, further adjustment of the clamping pressure is normally not needed. The friction pads provide the only substantial tension applied to the wire so that frictional resistance to the wire movement is substantially uniform.

The apparatus of this invention further includes a wire take-up assembly including a lightweight dancer arm pivoted adjacent one end and having an eyelet at its other end through which the wire passes. A bias acting on the dancer arm is provided to draw the wire during intervals in which there is a slack demand resulting from operation of the armature or other device which draws the wire. The bias may be in the form of a weight mounted on the dancer arm. The weight may be all that is needed for use with very fine wire, such as 43 gauge wire. A spring connected to the weight is used to increase the bias for use when dereeling heavier gauge wire.

The wire path through the tension assembly is vertical and the wire path in the take-up area is preferably horizontal, the change in direction being provided by a wire pulley. Further in accordance with this invention, a sensor is provided for monitoring rotation of the wire pulley, so that in the event of wire breakage the cessation of pulley rotation will be sensed. This event may be used to energize an alarm or to discontinue operation of the machine with which the apparatus of this invention is being used.

An object of this invention is to provide a simple, rugged, and inexpensive wire tension and take-up apparatus as described above, and also to provide such an apparatus which may occupy a minimum space. All the mechanical parts of this invention may be mounted upon a single plate which need be no larger than 8" x 8". The sensor for monitoring the rotation of the pulley and thus the wire breakage as described above may be mounted on the same plate.

Further in accordance with this invention, very simple means is provided for maintaining control of the wire to retain it on the wire pulley. This is done by the simple expedient of mounting a brush with bristles overlying the pulley which prevent the wire from jumping out of the pulley groove.

Other objects and advantages will become apparent from the drawings and the following description.

Figure 1 is a front elevational view with parts broken away, of the wire tension and take-up apparatus of this invention shown in association with a schematically illustrated flier and flier drive and control circuitry for an armature winding machine. Figure 1 also illustrates a portion of a wire guide cone used to restrict the wire in its path from a supply spool and a portion of a shaft for mounting the apparatus of this invention to the bed of an armature winding machine.

Figure 2 is a side elevational view of a portion of the apparatus of Figure 1 as indicated by arrows 2-2 thereof, and particularly illustrating a wire tension assembly.

Figure 3 is a cross-sectional view of a portion of Figure 1 indicated by arrows 3-3 thereof, and showing particularly a dancer arm pivot assembly.

Fiugure 4 is a top plan view of a portion of the apparatus of Figure 1 as indicated by arrows 4-4 thereof, and illustrating in particular a wire pulley, apparatus preventing the wire from jumping out of the pulley groove, and a sensor for monitoring rotation of the pulley. Figure 4 also schematically illustrates wire breakage detector circuitry electrically connected to the sensor.

Figure 5 schematically illustrates the wire pulley and sensor as viewed from the rear face of the pulley.

Figure 6 is a partially exploded perspective with parts broken away, of the apparatus and associated machine part shown in Figure 1 and further illustrating a wire supply spool.

With reference to Figures 1 and 6, the apparatus of this invention is generally designated 10, and as illustrated used to guide insulated wire from a wire supply spool 12 located in an open ended canister 14 to the hollow spindle 1 6 of a flier assembly, generally designated 1 8. Those familiar with armature winding machines will recognize that the wire is coursed from a flier pulley 20 at the free end of a flier arm 22 to the armature core (not shown) being wound.

The wire tension control apparatus of this invention may comprise a single support plate 24 mounted on a shaft 26 fixed to the bed (not shown) of the winding machine and held at a desired position thereon by a set screw 28 in a mounting block 30 affixed to the rear of the support plate 24 by screws 32.

Wire drawn from the spool is prevented from excessive ballooning by a wire cone 34 and extends into a vertically extending wire straightening tube 36 supported in a wire straightening bracket 38 mounted on the lower front face of the support plate 24 as by screws 40.

The wire cone 34 may be supported on the bracket 38 by a support assembly 42. The straightening tube 36 functions as an entrant wire guide to the tension and take-up apparatus of this invention. As those familiar with the art may be aware, the wire straightening tube 36 is preferably provided, at least at its lower end, with a tungsten carbide eyelet because the wire entering through the lower end of the straightening tube 36 does so in spiral fashion and could cause considerable abrasion at the lower end of the straightening tube 36.

Wire exiting from the upper end of the straightening tube 36 passes through a wire tensioning assembly generally designated 44 comprising, as best seen in Figures 2 and 6, a pair of circular mutually confronting and engaging friction pads 46 mounted between a pair of circular clamp members comprising a cup-like friction pad base member 48 and a spool shaped housing member 50 having a cup-like larger end portion 52 confronting the base 48 so that the base 48 and the larger end 52 of the housing 50 cooperate to firmly retain the friction pads 46 therebetween. The friction pad housing 50 further includes a smaller end portion 54 having an outwardly projecting cylindrical boss 56 designed to interfit within a coil spring 58.The friction pads 46, the base 48, and the housing 50 all have aligned apertures coaxial with a coil spring 58 for receiving an elongate threaded mounting stud 60 that extends therethrough and projects perpendicularly from the front face of the support plate 24. One end of the stud 60 extends through an aperture 62 and the support plate 24 and is threadedly engaged by a nut 64 at the rear face of the support plate 24. The opposite end of the stud 60 is threaded to be threadedly engaged by a pair of knurled adjustment nuts 66 and 68. As is apparent, the adjustment nut 66 may be rotated to place the spring 58 under greater compression and thereby cause the housing 50 to apply greater clamping pressure to the friction pads 46 to thereby increase the frictional resistance to movement of the wire W therebetween.

The friction pads could be made from various materials that may be relied upon to create a frictional resistance to wire movement without substantially abrading the insulating coating on the wire. Different materials may be useful for different types of wire. For very fine wire applications, in the range of approximately 36 to 43 gauge, a dense felt material is presently preferred. Pads 46 constructed of dense felt can be clamped in mutual engagement with the wire passing therethrough. Because felt is resilient, felt pads have a good wear resistance.

It may be noted that the construction of the housing 50 makes it easy for a workman to manually pull the housing 50 away from the support plate 24 against the bias of the spring 58 to separate the pads 46. When this is done, such as when an exhausted supply spool is replaced by a full spool, one may also, because of the manner in which the tension assembly parts are mounted on the stud 60, rotate the housing 50 and with it the adjacent pad 46 to thereby change the relative position of the outermost pad relative to the wire path and thus minimize wear on the pad. Of course, both pads could be manually rotated when the housing 50 is pulled away from the support plate 24.

It has been found that a relatively long length of the pad 46 should be engaged by the wire. if too short a length is engaged, the wire between the supply spool 12 and the tension assembly 44 may become unduly twisted and may kink, become snarled, and may break. For this reason, the axis of the stud 60 is as close as possible to the vertical path of the wire without interfering with the wire movement. For fine wire winding it has also been found that circular pads 46 made from heavy felt and having a diameter of approximately 2-1/8", so that the wire engages along approximately 2" of the pads, are satisfactory. Pads of a substantially smaller diameter, such as 1", would be unsatisfactory.

From the wire tension assembly 44, the wire W is guided along a path around a wire pulley 70 mounted by a roller bearing 72 on an axle 74. Axle 74 may conveniently be in the form of a screw having a large head abutting against the inner race of the bearing 72 and having a threaded end extending through an aperture 76 in the support plate 24 and engaged by a mounting nut 78. The pulley 70 is held in a spaced relation from the front face of the support plate 24 by a spacer 80 surrounding the axle 74.

The pulley 70 is so mounted on the support plate 24 that its wire receiving groove 82 is aligned vertically with the vertical axis of the wire straightening tube 36 to define the vertical path of the wire W, and horizontally with the axis of a flier spindle pulley 21. Because the wire changes direction at the pulley 70, there will be a tendency, in view of the high speed of operation of the armature winding machine, for the wire to jump out of the pulley groove 82. To prevent this from happening, a wire retaining member in the from of a brush 84 provided with bristles 86 is mounted by a screw 88 extending through an aperture in the brush 84 and an aligned tapped hole 90 in the support plate 24, the brush 84 being held in spaced relation to the front face of the support plate 24 by a spacer 92.The bristles 86 generally overlie the pulley 70 along the horizontal path of the wire exiting therefrom. Preferably, the bristles nearly or else lightly engage the wire to prevent it from jumping out of the pulley groove 82.

As noted above, the wire tension assembly 44 creates a substantially uniform tension on the wire W to provide the resistance necessary to enable proper operation of the flier assembly 1 8. During those intervals in which the wire demand created by rotation of the flier 18 is at a minimum or has ceased, the relatively slack wire condition is relieved or taken up by a take-up assembly generally designated 94 comprising a pair of spaced wire guides 96 and 98 having eyelets 100 and 102, respectively, which are aligned coaxially with the horizontal wire path extending from the wire pulley 70 to the flier spindle pulley 21. The wire guide assemblies 96 and 98 may comprise weldments with studs or the like (not shown) extending through apertures in the support plate 24 and mounted thereon in any suitable fashion.

The section of wire W spanning between the wire guide eyelets 100 and 102 extends through a dancer arm eyelet 104 at the end of a dancer arm 106 pivotally mounted upon the front face of the support plate 24 by a dancer arm pivot assembly 108 which as best shown on Figure 3, comprises a mounting shaft 100 rotatably mounted in a needle bearing 112 trapped within an aperture in the support plate 24. The shaft 110 has an enlarged head 11 4 with a transversely extending aperture 116 for receiving the dancer arm 106.

The front face of the enlarged head 114 has a hollow, threaded bore for a set screw 11 8 used to clamp the dancer arm 106 to the pivot assembly 108. A retaining collar 120 privided with a set screw 1 22 for holding the same to the shaft 110 is mounted on the shaft adjacent the rear face of the support plate 24. With proper lubrication, the pivot assembly 108 provides a freely rotating mounting for the dancer arm 106.

For best performance, the dancer arm 106 is preferably made as light weight as possible so that it can quickly move to the position illustrated in Figures 1 and 6 with its eyelet 104 aligned with the fixed wire guide eyelets 100 and 102 in response to wire being drawn by the flier assembly 1 8. One suitable dancer arm has been made from .035" piano wire provided with a small tungsten carbide eyelet having a 5/32" inside diameter.

The lightweight construction of the dancer arm 106 and the pivot assembly 108 combine to render the dancer arm 106 quickly responsive to increased tension in the wire passing between the wire guide eyelets 100 and 102. To also enable the dancer arm 106 to rapidly take up wire when it becomes slack, by movement of the dancer arm eyelet 104 downwardly from the horizontal wire path, the dancer arm 106 is biased to rotate in a clockwise direction as viewed in Figure 1 by bias means comprising a weight 124 that may be in the form of a short section of cylindrical metal rod having a transversely extending aperture through which the dancer arm 106 extends and having a tapped hole in one end thereof for receiving a set screw 126 for affixing the same to the dancer arm 106.The weight 124 further includes an aperture for receiving one end of a coil spring 128, the other end of which is received within one aperture 1 30 of a spring arm 1 32 that is mounted on the support plate 24 by one of the aforementioned mounted screws 32 and spaced from the front face of the support plate 24 by a spacer 1 34. The spring arm 1 32 is provided with several spaced apertures 1 30 to provide for additional adjustment of the spring tension applied to the dancer arm 106. Further adjustment may be obtained by loosening of the set screw 1 26 and moving the weight 124 therealong. In some applications, particularly when using very fine wire such as 43 gauge, the coil spring 28 may be unnecessary, the weight 124 being sufficient to provide the desired take-up.As will be apparent to those familiar with the art, dancer arm 106 will rotate in a clockwise direction as viewed in Figure 1 as needed to remove the slack created during intervals of flier rotation and at intervals when the fliers stop or are reversely rotating when lead wire connections are being formed. The maximum clockwise throw of the dancer arm 106 may be limited by a stop 1 36 which may comprise a roll pin inserted into an aperture in the support plate 24. Thus it is seen that the take-up assembly generally designated 94 provides for a widely adjustable bias to be applied to the dancer arm 106 which advantageously is provided with an eyelet 104 for taking up slack.The use of an eyelet 104 is considered necessary in view of the very high speeds at which the armature winding machine may operate to insure that the wire does not become disengaged from the dancer arm.

Further in accordance with this invention, the wire pulley 70 may be used in a system for detecting wire breakage that may be used to cause an alarm to be energized and/or to stop operation of the winding machine. With reference to Figures 5 and 6, the pulley 70 may comprise a nylon or other suitable plastic, non-conductive material having a metal foil or the like covering 138 over a circular segment of the rear face thereof. A proximity detector or other suitable probe 140 is mounted on the support plate 24 by a mounting plate 1 42 affixed to the rear face of the support plate 24 by the pulley axle 70 and its mounting nut 78 and by a mounting screw 144 threaded into a tapped hole 146 in the support plate 24.Preferably, the support plate 24 has a notch 148 formed therein through which the sensing probe 1 40 partly extends so that it may abut closely to the rear face of the wire pulley 70.

Signals from the probe 140 may be applied to suitable wire breakage detector circuitry schematically illustrated at 1 50 to monitor the pulley rotation, such signals being utilized by the detector 1 50 to determine whether the pulley 70 is still rotating, and in the event it stops rotating during an interval in which it should be rotating, which could be caused by wire breakage, a suitable alarm can be energized or the detector 1 50 could include circuitry, all as well known to those familiar to the art, which would cause interruption of the operation of conventional flier drive and control circuitry, schematically illustrated at 1 52 in Figure 1, used to control operation of the flier assembly 18.To insure that the pulley 70 constantly rotates while the wire W is being drawn from the supply spool 12, it may be necessary to loop the wire W completely around the pulley 70. In other cases, simply coursing the wire over the pulley 70 will be sufficient.

A suitable support plate 24 in accordance with this invention need be no larger than 8" x 8". All wire guide parts mounted on the support plate 24 are preferably spaced therefrom by a distance which causes the longitudinal axes of the entire stretch of wire from the lower end of the straightening tube 36 to the flier spindle pulley 21 to lie in a common vertical plane to minimize the forces acting on the wire as it travels through the apparatus of this invention.

As previously mentioned, the eyelet at the lower end of the straightening tube 36 and the dancer arm eyelet 104 are preferably made from tungsten carbide. This is because of its abrasive resistence. The same is true of the wire eyelets 100 and 102 and the dancer arm eyelet 104.

Claims (11)

1. A wire tension and take-up apparatus for use with wire being dereeled from a supply spool at high speeds which comprises: entrant wire guide means adjacent said spool through which wire therefrom passes; a take-up assembly comprising a pair of mutually spaced guide means engaged by said wire and defining a path along which said wire passes, a dancer arm including a dancer arm eyelet through which the section of wire spanning between said path defining guide means passes, and bias means for biasing said dancer arm to pull said last-mentioned section of wire out of said path defined by the guide means as needed to take up slack; and a wire tension assembly comprising friction means engaging the wire between said entrant guide means and said take-up assembly and further comprising adjustable clamp means for applying pressure to said friction means to create an adjustable frictional resistance to wire movement through said tension assembly.

2. Apparatus according to claim 1, wherein said friction means comprises pad means adapted to engage said wire over a length thereof so as substantially to prevent wire exiting from the spool from becoming twisted or snarled.

3. Apparatus according to claim 2, wherein said pad means comprises a dense felt material.

4. Apparatus according to claim 2 or 3, wherein said pad means comprises a pair of friction pads.

5. Apparatus according to claim 4, wherein the friction pads have aligned openings for receiving a stud projecting from a support plate, said adjustable clamp means comprises a clamp member engaging one of said pads and slidably mounted on said stud, a coil spring encircling said stud and engaging said clamp member, and an adjusting nut threadedly mounted on said stud and engaging said spring for compressing said spring.

6. Apparatus according to any one of the preceding claims, wherein said bias means includes a weight slidably moveable along said dancer arm and means for releasably clamping said weight to said dancer arm.

7. Apparatus according to claim 6, wherein said bias means further comprises a spring connected to said weight.

8. Apparatus according to any one of the preceding claims, which comprises direction change means aligned with said entrant guide means for causing said wire to move in a substantially vertical path between said entrant guide means and said direction change means, and said guide means cooperating with said direction change means to cause said wire to move in a substantially horizontal path as it moves past said direction change means.

9. Apparatus according to claim 8, wherein said direction change means comprises a pulley around at least a portion of which the wire extends.

10. Apparatus according to claim 9, which comprises means for monitoring the rotation of said pulley to detect wire breakage.

11. Apparatus according to claim 1, substantially as herein described with reference to any one of the figures of the accompanying drawings.