METHOD AND APPARATUS

BACKGROUND

1. Field of Invention

This invention relates to an armature for an electric motor and to a method and apparatus using a flier-type armature winding machine for winding armature coils and for connecting the sections of wires extending to and from the wound coils to commutator segments.

2. Incorporation by Reference

The disclosures of U.S. Patents to Miller, No. 3,913,220, granted October 21, 1972, and to Banner, No. 4,633,577, granted January 6, 1987, are hereby incorporated by reference herein. These are respectively referred to herein as the Miller 220 patent and the Banner 577 patent.

3. Prior Art and Other Considerations Armatures for 2-pole and 4-pole armatures with coils wound from insulated magnet wires are commonly wound using double flier armature winding machines which have two fliers that operate simultaneously for winding coils two-at-a-time from two different strands of wire, except in those cases in which the armature has an odd number of slots in which event one flier is idle while a coil or coils is wound by the other flier. Such armatures can also be wound using single flier winders which wind only one coil at a time

from a single strand of wire.

In the armature winding art, the section of the insulated wire strand between two successively wound coils is known as a lead wire or as a wire lead. The section of the wire strand that extends from the first commutator bar to the first coil wound by a flier is also considered to be a lead wire or wire lead but is more specifically referred to as a start wire or start lead. Likewise, the section of the wire strand that extends from the last coil wound by a flier to a commutator bar, which also is a lead wire or wire lead is more specifically called the finish wire or finish lead. These various wire sections are called wires or leads although, of course, they are all part of one continuous strand of wire.

When all of the coils are wound by a single flier, the start and finish wires are connected to the same commutator segment. When using a double flier armature winder, the finish wire formed from the strand wound into coils by one flier is connected to the same commutator segment to which the start wire of the other flier is connected, and vice versa.

The Miller 220 patent describes a method and apparatus using a flier-type armature winding machine for winding an armature in which the lead wires between coils are wrapped around the armature shaft in one direction from one wound coil to the next wound coil and in which intermediate portions of the lead wires are looped around commutator tangs. This basic method is now commonly used for winding armatures for 2-pole and 4-pole universal motors.

The Miller 220 patent does not address the connections of the start wires or the finish wires to the commutator tangs. There are now in use various methods for automatically connecting the start and finish wires to commutator tangs. In these methods, the wire portion extending from the last coil wound by a flier is gripped

by wire gripper device after the finish lead is connected to a tang and that wire portion is severed at or near the tang. This enables the wound armature to be removed from the winding machine and replaced by an unwound armature. At some time after the start wire is connected to a tang of the unwound armature, the section of wire clamped by the wire gripper is severed from the armature being wound. The remnant portion of wire clamped by the gripper is thereafter discarded. An apparatus for connecting start and finish wires is disclosed in the aforementioned Banner 577 patent.

Although the Miller 220 patent is directed to the manufacture of armatures having commutators with segments or bars provided with the tangs, the wrapping of the lead wires between coils in one direction around the armature shaft disclosed in the Miller 220 patent is also useful in the manufacture of armatures in which the commutator segments have wire-receiving slots instead of tangs. Commonly-owned U.S. patent application of Bradfute, Serial No. 08/051,022, filed April 21, 1993, shows such a method, and in addition, includes methods for connecting start and finish wires to the slotted commutators.

After a wound armature is removed from the winding station, the lead wire connections to the commutator are secured by a process referred to as commutator fusing or hot staking. During this process, the commutator segments and the coil lead wires are subjected to heat and pressure so that the insulating coating of the magnet wire in the area of the commutator segments is burned off and the commutator segments and the lead wires are fused together.

In the event that the coil lead wires extending to adjacent commutator segments are so close together that any portions of two lead wires from which the insulating coating has been burned off during the fusing operations engage one another, an electrical short will

be created and the armature rendered defective. The possibility of a short occurring is especially of concern in the areas in which the start and finish wires are connected to the same tang because, following conventional practice, portions of the finish lead must cross over the start wire looped around the same tang, whereby the finish wire is forced to lie in a path that brings it closer to the lead wire connection to the adjacent commutator tang than is the case of lead wires looped around adjacent tangs. Occasionally, the finish wire will be so close to the adjacent lead wire that there is a substantial probability that the armature windings may be shorted out.

SUMMARY An object of this invention is to provide an improved armature, an improved method for winding armatures, and an improved armature winding machine.

More particularly, this invention reduces the likelihood of creating an electrical short between a finish lead and an adjacent lead wire of an armature.

An armature in accordance with this invention may be entirely conventional except that each finish lead is extended from the last coil around the armature shaft to a start/finish commutator tang in a direction opposite to the direction in which the other leads are extended around the armature shaft and the finish lead is at least partially looped around the start/finish tang in a direction opposite to the direction in which the start lead is looped around the same tang. In the method of this invention, the armature may be wound using a conventional series of flier movements, commutator shield movements, lead guide movements, and armature rotations through the winding of the last coil or pair of coils to be wound. Thereafter, the armature is rotated in a direction opposite to its

normal direction of rotation in order to extend the finish wire or finish wires around the armature shaft in a direction opposite to which the start wires and other lead wires are extended. The reversely extended lead wire or wires are then reversely partly looped around the start/finish tangs. The effect of these operations is to at least partly loop the finish wire around the start/finish tang without extending the finish wire over the start wire segment leading from the same tang to a first wound coil.

The apparatus of this invention may also be essentially conventional except that the machine is provided with hooks or teeth for temporarily holding a finish wire extending from the coil last wound by its associated flier while the armature is rotated in a direction reverse from its normal direction of rotation to prevent a slack wire condition. An improved wire cutter arrangement may also be employed in the machine of this invention. This invention is intended primarily for use in the manufacture of armatures for 2-pole and 4- pole universal motors, having commutators with tangs but aspects of this invention may be useful for the manufacture of other types of armatures, such as 6-pole armatures and armatures having commutators with lead- receiving slots rather than tangs.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a wound armature in accordance with the prior art. FIG. 2 is a perspective view of an armature having the same general construction as the armature of FIG. 1 but which has lead wire connections in accordance with the present invention.

FIG. 3 is an exploded, fragmentary perspective view of a double flier armature winding machine in accordance with this invention and showing, in simplified

form, an armature which may be wound using the winding machine.

FIG. 4 is an enlarged, fragmentary, exploded perspective view of an inner commutator shield and a cutter of the machine of FIG. 3.

FIG. 5 is an enlarged, fragmentary perspective view of a wire hook mounted on the outer shield of the machine of FIG. 3.

FIG. 6 is an fragmentary perspective view of the double flier armature winding machine of FIG. 3 showing the armature after it has been wound with coils but before the finish wires are connected to commutator tangs, and shows the first steps in the connection of one of the finish wires. FIG. 7 through 11 are each fragmentary perspective views of the same portion of the armature winding machine shown in FIG. 4 showing, in seguence, subseguent steps in the connection of one of the finish wires. FIG. 12 is a fragmentary, exploded perspective view of a modification of the inner commutator shield and the cutter shown in FIG. 4.

FIG. 13 is a fragmentary perspective view of the outer shield provided with a modification of the wire hook illustrated in FIG. 5.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring to FIG. 1, an armature, generally designated 18, for a 4-pole universal motor, comprises an armature core 20 having a plurality of circumferentially- spaced, radially extending, coil-receiving slots 22 and a commutator 24 having plurality of circumferentially spaced bars 26, each of which is provided with a tang 28 are shown mounted on an armature shaft 30. Plural coils 32 wound from magnet wire are formed in pairs of the armature core slots 22 and each of the lead wires, designated 34, between successively wound coils are

connected to a respective one of the commutator tangs 28. The coils 32 of FIG. 1 are representative of those wound two-at-a-time by a double flier armature winding machine. The start wire, designated 36, of the coils wound by one flier (not shown) is looped around one of the tangs, referred to herein as the start/finish wire tang 28A, and the finish wire, designated 38, of the coils wound by the other flier (not shown) are partially looped around the same tang 28A. Of course, there is another tang (not shown) about which a different start wire and a different finish wire would be looped, but these parts are hidden from view in FIG. l. If the coils had all been wound one-at-a-time by a single flier, there would only be one start wire and one finish wire and they would both be part of the same strand of wire.

In FIG. 1 it will be observed that the finish wire 38 is closely adjacent to the lead wire, designated 34A, looped around the commutator tang 28 next adjacent the start/finish wire tang 28A. With the finish wire 38 so close to the adjacent lead wire 34A, there is a significant danger that the parts of these wires will come into contact with one another after the fusing operations have removed their insulating coatings and create an electrical short. This problem is created by the manner in which start and finish wires are connected to the same start/finish tang using a method such as that taught in the Banner 577 patent in contrast to the manner in which lead wire between successively wound coils are made in accordance with method described in the Miller 220 patent. In accordance with the Miller 220 patent teaching, each lead wire segment extending from a wound coil is looped at least partly around the armature shaft in a first direction past the tang to which it is to be connected, then reversely extended over the same tang. The lead wire is then extended to the beginning of the next coil in the first direction around the armature shaft. Accordingly, inherently as a result of the

practice of the method of the Miller 220 patent, the lead wire segment leading from a tang to the start of the next coil crosses over the top of its associated lead wire segment leading from the end of the next previously wound coil to the same tang. One of the benefits of the Miller 220 method is that the looped lead wire segments cross over one another close to the tang around which they extend and are sufficiently remote from adjacent lead wires that electrical shorting between adjacent lead wires is unlikely.

In contrast to the Miller 220 method, in the practice of the known methods for automatically forming start and finish wire connections for armatures otherwise wound in accordance with the method of the Miller 220 patent, of which the method disclosed in the Banner 577 is representative, a start wire leading to the first coil is itself looped around a start/finish wire tang and extended from that tang around the armature shaft in the first direction, i.e. the same direction that all other lead wires are extended around the shaft, to the first coil to be wound by the associated flier. The start wire must extend around the shaft in the same direction as the lead wires between coils to avoid interference with the subseguent coil winding and lead wire connecting operations. In accordance with prior practice, a finish wire is extended in the same, first, direction around the armature shaft and crosses over, rather than under, the start wire, and is at least partially looped around a start/finish tang in the same direction as the start wire loop. The portions of the finish wire that cross over and loop around the start wire are, accordingly, forced to follow a path that brings it closer to the lead wire connection to the adjacent commutator tang than is the case of lead wires looped around adjacent tangs. Occasionally, the finish wire will be so close to the adjacent lead wire that there is a substantial probability that the armature windings may be shorted

out.

The problem discussed above is overcome in accordance with this invention by extending the finish wire from the last coil wound by a flier around the armature shaft in the direction opposite to the first direction that all of the other lead wires are extended around the shaft, and looping the finish wire about a start/finish wire tang in a direction opposite to the direction that a start wire is looped around the same start/finish wire tang. FIG. 2 shows an armature, generally designated 40, having the same core, commutator and shaft as the armature 18 of FIG. 1, and to which like parts are identified by like reference numbers. The armature 40 of FIG. 2 has the same coil windings and lead wire connections as the armature 18 of FIG. 1, except that the finish wire, designated 42 in FIG. 2, is extended around the armature shaft 30 in the second direction opposite to the first direction in which the start wire 36 and all of the other lead wires 34 are extended around the shaft 30. In addition, the finish wire 42 is extended past the start/finish tang 28A in the second, opposite direction and then partly looped around the start/finish tang 28A in a direction opposite to the direction in which the start wire 36 is looped about the same tang 28A.

FIG. 3 shows parts of an armature winding machine, generally designated 44, in accordance with this invention. Machine 44, which may be programmed to operate as described below using conventional machine controls (not shown) , includes two fliers 46 and 48 mounted on spindles 50 and 52, respectively, that rotate about a common horizontal axis extending perpendicularly through the center of the armature core, for simultaneously winding two coils, one by each flier, onto an armature subassembly 54. The subassembly 54 is shown in simplified form because it does not include slot insulators in the armature core slots 22 and insulating

end plates or laminations at the ends of the armature core 20, such being well known to those familiar with the art. When the fliers 46 and 48 are rotating to wind coils into pairs of armature core slots 22, two strands of magnet wire, designated Wl and W2, are drawn from separate sources (not shown) of wire under tension, through the flier spindles 50 and 52, respectively, and into spaced core slots 22. During each winding operation, the armature shaft 30 is held with its axis perpendicular to the axis of rotation of the fliers 46 and 48 by a rotatable collet (not shown) surrounded by an inner commutator shield 56. The collet is rotatably driven about its axis by an armature rotator (not shown) as needed to index the armature subassembly 54 to present new pairs of slots 22 in position to have coils 32 wound in them and to connect the lead wires, including the start and finish wire 36 and 42, to the commutator tangs 28. The armature rotator is conventional and may be of the type shown in the Banner 577 patent, but preferably driven be a servomotor, such as an armature rotated presently marketed by Globe Products Inc. of Huber Heights, Ohio, the assignee of the present application. During the winding of a pair of coils 32, a pair of chucks or winding forms 58 centered on the horizontal axis of rotation of the fliers 46 and 48 tightly grip the sides of the armature core 20 and guide the wires into the core slots 22 to form coils 32 therein. One of the winding forms 58, in this case the right side (as viewed in FIG. 3) winding form 58 has a spring-biased stop dog 60 which enters one of the core slots 22 to assist in obtaining the precise desired angular orientation of the subassembly 54 at the outset of the winding procedure. The stop dog 60 operates in one direction only to stop rotation of the subassembly 54. At the beginning of the winding procedure, the armature rotator rotates the armature subassembly 54 in a direction opposite to the direction the armature subassembly 54 is normally rotated

throughout the remainder of the winding operations. During such reverse rotation, the stop dog 60 enters one of the core slots 22 and prevents further reverse rotation. Since the stop dog 60 is ineffective to prevent the normal or forward direction of rotation of the armature subassembly 54, it is otherwise not used during the winding of an armature.

When winding armatures for 4-pole motors, the wires Wl and W2 are also guided by upper and lower center wire guides 62 and 64 which are centered on a vertical axis extending perpendicularly through the armature core 20 and which have wire guiding surfaces 66 that assist in directing the wires into the appropriate armature core slots 22. Each of the center wire guides 62 and 64 in accordance with this invention has a vertically extending tooth 68 that extends toward the horizontal plane that contains the axes of rotation of the flier spindles 50 and 52 and the armature shaft 30 and which is spaced to one side or the other of the vertical plane which contains the axis of the armature shaft 30. The precise positions of the hooks or teeth 68 can be determined by trial and error so that they may function as described below.

The particular center wire guides 62 and 64 shown in FIG. 3 have associated with them tampers 74 driven by air actuators 76 which tamp the ends of the coils 32 radially inwardly toward the armature shaft. The use of such tampers is well known and understood. Since they are not involved in the instant invention, they are not completely illustrated or further described herein.

As is conventional, the inner shield 56 has diametrically opposed notches 78 that expose a pair of tangs 28. Only one of the notches 78 is illustrated in the drawings. When coils 32 are being wound, the inner shield notches 78 are covered by an axially movable outer shield 80 so that the exposed tangs 28 do not engage the

portions of the wires being wound into coils 32. When appropriate during a winding cycle, the outer shield 80 is retracted so that the tangs 28 exposed by the inner shield notches 78 can have lead wires looped around them.

For purposes of automatically connecting the start and finish wires to the start/finish tangs 28A, a pair of movable wire clamps or grippers 82 are provided adjacent the commutator shields 56, 80 and the inner shield 56 has a cutting blade 84, and a pair of wire traps or fingers 86 are mounted on the free end of the outer shield 80. The functions of these parts will be described below. Briefly, it may be noted that the Banner 577 patent describes a start and finish wire connecting and trimming or cutting method in which the start and finish wires are severed by moving wire grippers, similar to the grippers or wire clamps 82 illustrated in FIG. 3 hereof, to draw wire segments across a knife edge that is separate from the inner shield. Corey et al. patent 5,187,856 shows an improvement on the Banner 577 method in this regard. Such a method could be practiced with aspects of this invention, but such a method is not well suited for use with armatures wound from wires having relatively large diameters. The method described herein is better to suited for use with large wire sizes.

With reference to FIG. 4, the cutting blade 84 comprises a generally Z-shaped plate having a center, axially extending leg 88 received within an axially extending recess 90 in the inner shield 56 and two circumferentially extending legs 92, one at each end of the center leg 88. Each circumferentially extending leg 92 has a sharp cutting or knife edge 94 which may be exposed in an opening or 95 in the inner shield 56. One of the circumferential legs 92 is exposed to the front of the inner shield 56 and the other is located within a transversely extending recess 96 located in the inner

shield 56 at the inner end of the axially extending recess 90. As is apparent, the blade 84 may be reversed to expose one or the other of the cutting edges 92 at the free end of the inner shield 56. The center leg 88 has a rectangular, downwardly projecting lug or key 98 at its mid-section and a counterbored bore 100 passing centrally through the blade 84 and the key 98. A milled groove 102 is cut transversely across the axially extending recess 90 to a depth greater than the depth of the axially extending recess 90. A tapped hole 104 is formed centrally of the milled groove 102 and a flat head screw 106 extends through the bore 100 and threadedly engages in the tapped hole 108 to secure the cutter blade 84 in position in the inner shield notch 95 and also to secure the key 98 in the transverse groove 102. This type of cutter blade mounting is not new, having been shown for a cutter blade having a different shape in U.S. Patent 4,827,601.

With reference to FIGS. 3 and 5, each wire trap or finger 86 comprises, as conventional, an elongate bar 110 mounted on the outer shield 80 so that it extends axially along the outer shield 80, and has a circumferentially extending notch 112 formed at its outer end through which a lead wire may be extended so that, when the outer shield 80 is retracted, the lead wire 34 is forcefully pulled over the sharp edge 94 of the cutter blade 84 to sever the lead wire 34. In accordance with this invention, the inside leading edge of the bar 110 has a groove 114 to better position the lead wires during cutting operations.

In operation of the apparatus of this invention to produce the armature 40 of FIG. 2, the start wires 36 may be connected to the start/finish tangs 28A in a conventional manner using, for example, a procedure similar to that disclosed in the Banner 577 patent using, however, the cutter blades 84 and the wire traps or fingers 86. Also, the winding of the armature and

lead wire connections to the tangs can progress 28 as conventional, using combined motions of the fliers 70 and 72, the armature rotator and the outer shields 80, up to the point in the winding cycle when all of the coils 32 have been wound but the finish wires 42 have not yet been connected to the start/finish tangs 28A. This is the beginning point in the portion of the winding cycle represented in FIG. 6.

FIGS. 6 through 11 illustrate a series of steps to effect connection of a finish wire 42 to a start/finish tang 28A, using the left side flier 70. It will be understood that the other flier 72 will undergo the same series of motions to connect the other finish wire 42 to the other start/finish tang 28A. In FIG. 6, the left flier 70 is shown by phantom lines in its forward stop position at the end of the winding of the last coil 32, which was wound in a clockwise direction as viewed in FIG. 6. At this time, the flier 70 is reversely rotated to a reverse stop position shown by full lines in FIG. 6, causing the finish wire 42, which extends directly from an armature core slot 22 containing the last coil wound, to be hooked to the tooth 68 projecting downwardly from the upper center wire guide 62. After the parts reach this position, the chucks 58 are spread apart by a conventional chuck positioning cylinder (not shown) to enable the armature to be rotated in a direction which is reverse to the direction in which it is rotated during the preceding winding operations. If the chucks 58 were not separated from the armature at this time, reverse rotation of the armature would be prevented by the stop dog 60. The hooking of the finish wire 42 by the tooth 68 is important at this time because, if not so hooked, the reverse rotation of the armature would cause the finish wire 42 to go slack and possibly unravel out of the armature core slot 22. (The lead wires 34 between successively wound coils 32 do not become hooked by the tooth 68 upon reverse rotation of

the flier 70 because they follow a different path, extending to the flier 70 from a commutator tang 28 instead of directly from an armature core slot 22.

After the chucks 58 are retracted as indicated by the arrows in FIG. 6, the armature rotator causes the armature 40 to reversely rotate (in a top coming direction as indicated by the curved arrow in FIG. 7) through a significant portion of one complete 360 degree rotation into the position shown in FIG. 7. As the armature rotates in the reverse direction, the finish wire 42 is cammed by end turns of the wound coils 32 toward the shields 56 and 80 and therefore becomes unhooked from the tooth 68, as is also shown in FIG. 7. After completion of the reverse rotation of the armature, the chucks 58 are extended to again tightly engage the armature core 20 as indicated by the straight arrows in FIG. 7.

With reference to FIG. 8, the wire is now partly looped around a start/finish tang 28A by retracting the outer shield 80 to expose the start/finish tangs 28A, moving in a pair of lead guides 118 and rotating the flier 70 in the forward going direction, as indicated by the curved arrow in FIG. 8, to the forward stop position as shown by phantom lines in FIG. 8. The lead guides 118 function to insure that the lead wires, including the start and finish wires are guided around or behind the commutator tangs. Lead guides are conventional and not otherwise disclosed or described herein. Reference may be had to U.S. patent 3,713,598, which explains the purpose of wire or lead guides such as the lead guides 118.

With reference to FIG. 9, after the finish wire 42 is partly looped around the start/finish tang 28A, the lead guides 118 are retracted, the outer shield 80 extended to again cover the inner shield notches 78 and the flier 70 returned to its reverse stop position as shown in FIG. 9. The pressure on the chucks 58 is

relieved so that the armature can be rotated without interference from the chucks 58, and the wire clamps or grippers 82 are moved into positions close to the center wire guides. The armature is now rotated by the armature rotator in its forward or top going direction of rotation as shown in FIG. 10 to bring the finish wires 42 into the jaw of the wire gripper 82. The chucks 58 are then again placed under pressure to tightly grip the armature core 20, and the wire grippers 82 closed to grip the finish wire 42 as also shown in FIG. 10. With the finish wires 42 securely clamped by the wire grippers 82, the chucks 58 may again be opened to permit of a reverse rotation of the armature, as indicated by the dotted line arrow in FIG. 10, to the optimum position for cutting the finish leads 42 free from the sections of wire clamped by the grippers 82. The outer shield 80 is then retracted as shown in FIG. 11 to cause the finish leads 42 to be cut by the cutter blades 84.

The purpose of having the cutting edges 94 of the cutter blades 84 extend through a substantial circumferential distance is to enable the start wire 36 to be cut against a different portion of the cutting edge 94 than the finish wire 42. This may not always be used but can in some cases be of considerable importance in order to leave the least possible length of cut wire extending from the start/finish tangs. In order to better locate either a start or a finish wire, it can be aligned with the groove 114 in the wire trap notch 112 so that, as the wire trap 86 is retracted to sever the start or finish wire, the wire is forced by the groove 114 into a predetermined position relative to the cutter blade 84.

FIG. 12 shows a modified cutter blade 120, which is L-shaped and has only one cutting edge, designated 121. FIG. 13 shows a modified wire trap 122 which has a vertically extending groove in its notch 126. It may noted that one of the start and finish wires may be located in the vertical groove 124 and the other could

be located deeper in the notch 126 for cutting the start and finish wires at different positions.

While the invention has been particularly shown and described with reference to the preferred embodiments thereof, it will be understood by those skilled in the art that various alterations in form and detail may be made therein without departing from the spirit and scope of the invention.