CA1123586A - Method and apparatus for assembling dynamoelectric machine stators - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
Method and apparatus for forming a stator for a dynamoelectric machine by inserting prewound coils into a slotted stator core in-cludes enlarging the slot openings or gap between certain adjacent pairs of stator teeth, placing the prewound stator windings in se-lected stator core slots and thereafter reducing the slot opening or gap between those certain adjacent pairs of teeth. The disclo-sure apparatus includes a stator bore support and a series of punches to be placed in stator slots and collapsed radially in-wardly to bend the stator teeth tips to conform to the bore sup-port. An otherwise conventional coil inserting or injecting machine has unique blades, each of which has a pair of elongated depres-sions for accepting the respective formed stator teeth tips, and a pair of ribs outside the depression for spanning the corresponding tooth. Reforming of the stator teeth so as to provide a cylindri-cal bore stator may be accomplished by a plurality of cylindrical rollers which simultaneously engage the stator bore and traverse that bore interior surface to displace the stator teeth tips ra-dially outwardly, thereby providing a wound stator for further processing having a substantially reduced iron gap or for a given iron gap containing windings of a larger wire size than normally insertable in a stator having that iron gap. The slot openings may be enlarged either by mechanical forming of the stator tooth tips or the stator laminations may be initially stamped with this deformation so that the stator core or stack of such laminations need not be mechanically formed to increase the iron gap available for the wire insertion process.

Description

B~CKGRoU~aD _F TH:E: IMVF.NTION
The pxesent invention relates generally to apparatus and tech-niques for producing electromagnetic devices and more particularly to such techniques and app2ratus for making stators for dynamo-electric machines.
In the manufacture of a dynamoelectric machine stator, a num-ber of relatively thin stator laminations are punched or stamped from a strip of m~terial and stacked together to form a stator core typically having a centrally disposed axially extending generall.y cylindrical bore with a plurality o~ axially elongated slots com-munica-ting with ~hat bore as defined by a like plurality of statQr teeth separating adjacent slots. The stator teeth frequentl~ have tips near the stator bore extending toward one another, formi.ng a gap where the slot communicates with the bore. T~indings are then disposed in the stator slots hy either in-slot winding techniques or by ~orming the windings and then axi.ally or xadially inserting those windings into the appropriate core slot.
The size wire which may be used in a stator winding is lim-ited by the gap between adjacent pairs of stator teeth, or stating the same ~act in a different manner, for a given size wire the gap between adjacent stator teeth must be sufficiently large to admit that si~e wire. While different considerations prevail for the different techniques of placins the windings in the stator core slots, th~ slot gap still limits the wire size, or the wire size limits the slot gap, and this gap cannot be further reduced, or the wire size increased, according to the known stator fabricating techniques.
SUMMA.~Y Ul' Among the several objects o this invent.ion may be noted the provision of a dynamoelectric machine stator fabricating techni-que for increasing the wire size and~or decreasing the gap between adjacent stator teeth as compared to the known fabricating tech-~23~

niques; -the provis~on of method and apparatus Eor improving dynamoelectric machine efficiency; the provision of an improved process Eor inserting prewound coils into the slots of stat~ cores; and the provision of a method for making a stator for a dynamoelectric machine which overcomes the limitation imposed by the dimension of the gap hetween ad~acent stator teeth.
In general~ a process for inserting prewound coils into the slots of stator cores, in one form of the inventi.on, includes enlarging certain of the core slot openings, passing prewound coils through selected enlarged slot openings, and reducing the certain slot openings to provide the wound stator.
In a specific embodiment of the invention there is provided a method o:E making a stator for a dynamo~
electric machine having a stator core with a centrally disposed axially extendinq generall~ cylindrical bore, and with a plurality of axiall~ elongated slots communicatin~
with that bore, and a like plurality of stator teeth separating adjacent slots, with adjacent tips of the stator teeth forming a ~ap where the slots co~unicate with the bore, in one form of the invention, includes enlarging the gap between at least certain ad~acent pairs of teeth, placing stator windings in selected slots, and reducing the gap between the at least certain adjacent pairs of teeth.
According to another aspect of the present invention there is provided an apparatus for assembling coils into the slots of stators and the like, the apparatus having a stator bore support Eor engaginq and supporting a stator core with means for forming stator teeth tips radiall~ inward to conform the teeth to the mb/ - 2 -bore support. A pl~rality of qenerally circular disposed parallel extending ~lades are provided for supporting coils and a stator sore with means heing movable along the hlades for forcing coils along the hlades and into stator core sl~ts. Means is provided for reforminq stator teeth tips r~dially outward to provide a cylindrical bore stator.
In a specific embodiment of the invention, there is provided a~ apparatus for assembling coils in the slots of stators and the like, the apparatus including a stator ~ore support for enqaginq and supportinq a stator core, alonq ~ith punches or other means for forming stator teeth tips radially inwara to conform tlle teeth to the bore support. A plurality of ~enerally circularly disPosed parallel extendinq hlades support the coils and stator core while a stripper or other member moves alonq the blades for forcing coils along the blades and into stator core slots. The stator teeth tips are then reformed radially outward to provide a cylindrical bore stator by, for example, a plurality of cylindrical rollers, which simultaneous- -mb/~,,~i - 2a -~ ` .
j,:

ly enyage and traverse the stator bore interi~r, displacing the stator teeth tips radially outwardly to the positions they occupied prior to forming.

BRIEF DESCRIPTION OF T~E DRAWING
Fig. 1 is a partial end view of a dynamoelectric machine stator core comparing the techni~ues of the present invention to known prior art;
Figs. 2A, 2B, 2C and 2D illustrate apparatus for enlarging the iron gap between certain adjacent pairs of stator core teeth;
Fig. 3 illustrates a s~ator portion with enlarged gap in posi-tion on modified coil inserting equipment;
Fig. 4 is a perspective view of a stator and one device for reducing the previously enlarged gap bPtween certain adjacent pairs of stator core teeth;
Figs. SA and 5B are end and partial section viaws respectively of a portion of a stator in conjunction with another device for re~
ducing the gap between certain adjacent: pairs of stator core teeth;
and Fig. 6 is a bloc~ diagram illustrating one method of stator fabrication according to the present invention.
Corresponding reference characters indicate corresponding parts throughout the several views of the drawing.
The exempiifications set out herein illustrate the invention in one form thereof and such exemplifications are not to ba con-strued as limiting in any manner the scope of the invention.
DESCRIP~ION OF T~E PREFERRED E~BODIMENT
In Fig. 1 a stator core 11 has slots 13 J 15 and 17 into which windings are to be pl~ced eithex by directly winding in the selected slots or by preforming the winding and axially or radially placing that preformed winding in the slots. Each adjacent pair of slots has one side thereof deined by a stator tooth such as 19 or 21, and adjacent pairs of such stator teeth have tips 23, 25, 27, 29, 31 and 33~ which define therebetween an ixon gap through which the wire or winding must pass to be placed in the stator cor~
A conventional iron gap I is depicted between the tips 27 and ~9~
For the axial insertion of prewouna coils, a stator core is placed on a plurality of genera7ly circularly disposed parallel ex-tending blades which 5upport coils as well as that stator core, and a stripper or other device moves along the blades, moving the coils therealong and into stator core slots. Such axial insertion of pre-wound coils i5 illustrated, for example, in Uni~ed States Patent

2,432,267 to Adamson, United States Patent No 3,324,536 to ~Iill, and United States Patent No. 3,402,462 to Walker, et al. A representa-tive pair of such blad~s 35 and 37 are illustrated in Fig. 1, and such blades typically have lips 39 and 41 which overlie the respec-tive stator teeth tips 23 and 25 to protect the winding from the relatively rough stator core during the insertion processO Thus, such inserter blades, and particularly the lips 39 and 41, reduce the gap available for the insertion process rom the iron gap I
down to the blade gap B, as illustrated. A larger blade gap~ of course, ~acilitates the insertion process and allows w.indings of a larger wire size to be inserted, if desired. The larger blade gap, of course, necessitates a greater iron gap r which greater iron gaps may lead in the resultant motor to decreases in operating eficiency.
Greater blade gap without a concomitant increase in iron gap and/or a decreased iron gap without a concomitant decrease in blade gap may be achieved by orming ~he stator teeth tips r a~ illustra-ted, by tips 31 and 330 The iron gap I and blade gap B for slot 13, as depicted, illustxate the conventional approach to this prob-lem, however, an iro~ gap, as i~lustrated for slot 15, nearly the s~me as the blade gap B illustrated for slot 17/ may be achieved by deformincJ the tooth tip9 to a new wider iron gap I in the manner ~ $ ~3 illustrated for 510t 17. This deformation, as illustrated for tips 31 and 33/ may of course be provided by the stator lamination punch-ing or stamping die, with no enlarging of the gap between certain adjacent pa.irs of teeth occurring after the stator lamination is formed, however since blanks for rotor laminations are frequently formed from the central portion stalnped out of the stator lamina tion, such a die configuration may be undesirable r in which event the enlarging of the gaps between the pairs of ~eeth may ~ake place after initial stamping of the s-tator laminations.
In Fig. 2, a punch 51 has been axially inserted into the stator slot 45, and when forced radially inward to the position illustra-ted as 51', functions to deflect the adjacent stator teeth tips 47 and 49 toward the stator bore and into the positions 47' and 49', there-by increasing the iron gap. In practice, a number of such punches, such as 51, would be generally circularly disposed, and alignable and ax.ially insertable into the appropriate stator slots simultane-ously. To enlarge the several slot ope'nings, pairs of wedge shaped members, such as 53 and 55, are relativel,y moved to urge the respec-ti~e punches in a collapsing or radially inward direction to simul~
taneously fQrm as man~ tooth tips as desirea for the particular winding .insertion process. Wedge shaped member 55 may be affixed to a base 57, which base fixedly supports a bore support member 5~, and which supports the several punches, such as 51, in a movable manner. A second frame member 61 may movably support the several wedges, such as 53, with wedges 53 and punches 51, for example, bei~g spring loaded in a radial c>utwaxd dixection. Proper align~
ment of a stator core 63 and the upper and lower frame members 57 and 61 allows the simultaneous alignment of a punch ancl pair of wedge shaped members in each stator slot and forcing the frame po.r tions 57 and 61 toward one another, si.multaneously deforms each pertaining pair of tooth -tips. The actual bend or defvrmation given a tooth tip in this process, o~ cvurse/ depends upon the configura~

tion of punch 43, as well as the configuration of the adjoining bore support portion of bore suppor~ 59. After forming in ~his manner, the stator core has the tooth configllration illustrated in Fig. 3.
In Fig. 3, the windings to be inserted are placed over inser-ter blades, such as 65, 67 and 6g, which are circularly disposed and parallel extendin~ blades similar to ~hose disclosed in the aforementioned United States Patents Nos. 3,324,536 and 3,402,462 with insertion occurring in the manner disclosed therein. It will be notedr however, that these blades differ from those of the prior art in having a pair of elongated depressions 71 and 73 for accep-ting the respective formed stator teeth tips 75 and 77, as well as a pair of ribs 79 and 81 outside the depressions 71 and 73 for spanning the corresponding tooth 83. A stripper 85 is then passed through the stator bore to axially insert the windings in a con-ventional manner.
With windings, such as 87, disposed in the stator slots, stator 89 of Fig. 4 may simply be passed over a cylindrical ~orm-ing tool 91 to deform the stator teeth tips radially outwardly to return the stator bore to its cylindrical configuration, while reducing th~ gap be~ween adjacent pairs of teeth, providing more narrow slot openings than would be otherwise achievable. Forming tool 91 would, of course, have the diameter o its maln cylindrical por~ion nearly identical to the diameter of the finished stator bsre and may include a tapered portion 93 to aid the passage of the stator c~er the tool and to cause the reforming of the stator tooth tips to be somewhat progressive.
The stator bore may he returned to a cylindrical confi~uration and the gap between adjacent pairs of teeth reduced by reforming the previously de~ormed tips employing rollers, such as 117, 11~, 121 and 123 in Figs. 5A and 5B. The rollers engage and rollingly traverse the stator ~ore interior to displace the stator teeth tips, 5~6 5uch as 101, radially outwar~ly to their final position. The rol-lers may be cylinclrical and rigidly positioned about a circle so that their outermost surfaces coincide with the completed stator bore. If ~he rollers are ixed in location, they are spaced and sized so that a stator may be placed thereover with the deformed tips falling between rollers, whereupon the stator revolves relative to the rollers to deform the stator teeth tips. Alternately, the rollers 117, 119, 121 and 123 may be tapered and movable outwardly generall~ perpenclicular to their respective axes by cams or the ta-pered roller 133 or otherwise to create a progressive reforming of the stator teeth tips, as desired.
The reforming of the stator teeth is rather easily achieved by the apparatus illustrated in Figs. 5A and 5B. The stator 89 with its deformed stator tooth tips is placed over the our tapered rollers 117, 119, 121 and 123, and thereafter the tapered central roller 133 is forced toward the several opposingly tapered rollers to urge those four rollers outwardly to reform the stator bore.
The ~our outer rollers haYe their axlesl such as 125, disposed in elongated slots, such as 129 r at either end of each roller so as to allow the free radial movement of those four rollers when urged out-wardly ~nd into engagement with the stator bvre.
From the foregoing it is now appar~nt that a novel method and apparatus for fabricating dynamoelectric machine stators has been presented meetin~ the objects and advantageous features set out hereinbe~ore as well as others. Numerolls modifications will readily sugges~ themselves to those of ordinary skill in this art. For ex-ample, insulative slot liners 103 and bore wedges 105 may be inser-ted in the stator in the conventional manner and numerous techniques may be employed in deforming and reforming the pertaining stator tooth tips. Thus, or example in the process depicted in Fig. 6, the step 107 of deforming these teeth tips may be incorporated into the step 109 of stamping the stator laminations, as earlier discussed.

" ', : .

The laminations may be assemblecl at 111 to form a stator core by tlle conventional welding or bolting together of those laminations or by clea-tin~ techniques currently in use in the stator core fab-ricating art. ~he step o~ inserting stator windings at 113 may include ~he insertion of insulating and bore wedges, and may be a single in~ertion step of a single winding, or several inslertion steps of different windings, or may even be the con~emporaneous insertion of a plurality of different windings. The present in-vention may also be advantageously employed with other winding techniques such as in-slot and hand-placed winding. Two techniques, both of which deviate the stator tooth tips radially inwardly, have been disclosed, however, those tooth tips may be deviated in other ways or in other directions, as desired, so as to increase the iron gap therebetween. TWQ techniques for the reforming step 115 have been disclosed, however, other approaches could be employed. These and other modifications may be made by those having ordinary skill in the art without departing from the s,pirit of the invention or the ~cope thereof as illustrated by the~ claims which ~ollow.

2~

Claims (16)

The embodiments of the invention in which an exclusive prop-erty or privilege is claimed are defined as follows:

1. A method of making a stator for a dynamoelectric machine having a stator core with a centrally disposed axially extending generally cylindrical bore, a plurality of axially elongated slots communicating with the bore and a like plurality of stator teeth separating adjacent slots, adjacent tips of the stator teeth forming a gap where the slots communicate with the bore and comprising the steps of:
enlarging the gap between at least certain adjacent pairs of teeth throughout substantially the entire axial extent thereof;
assembling stator windings in selected slots including slots the associated gap of which has been enlarged; and reducing the gap between the at least certain adjacent pairs of teeth throughout substantially the entire axial extent thereof.

2. The method of Claim 1 wherein the gaps which are enlarged and then reduced include at least all those gaps associated with the selected slots.

3. A method of making a stator for a dynamoelectric machine having a stator core with a centrally disposed axially extending generally cylindrical bore, a plurality of axially elongated slots communicating with the bore and a like plurality of stator teeth separating adjacent slots, adjacent tips of the stator teeth form-ing a gap where the slots communicate with the bore and comprising the steps of:
enlarging the gap between at least certain adjacent pairs of teeth by deforming adjacent stator teeth tips radially inward;
assembling stator windings in selected slots including slots the associated gap of which has been enlarged; and reducing the gap between the at least certain adjacent pairs of teeth.

4. The method of Claim 3 wherein the gaps are reduced by reforming the stator teeth tips radially outward to return the stator bore to a cylindrical form.

5. The method of Claim 3 wherein the step of enlarging includes radially supporting stator teeth between the teeth tips.

6. A process for inserting prewound coils into the slots of a stator core having an axially extending bore and slot openings about the periphery of the bore comprising the steps of: enlarging certain of the slot openings throughout substantially the entire axial extent thereof; passing prewound coils through selected enlarged slot openings; and reducing the certain slot openings throughout substantially the entire axial extent thereof.

7. The process of Claim 6 wherein the step of enlarging includes passing a number of punches axially each into a separate stator slot, collapsing the punches radially inward to deflect the tips of adjacent stator teeth toward the stator bore, and axially removing the number of punches from the stator slots.

8. The process of Claim 7 wherein the step of reducing includes forcing the deflected stator teeth tips radially outward to form a cylindrical stator bore.

9. A process for inserting prewound coils into the slots of a stator core having an axially extending bore and slot openings about the periphery of the bore comprising the steps of:
enlarging certain of the slot openings by deforming adjacent stator teeth tips radially inward;
passing prewound coils through selected enlarged slot openings; and reducing the certain slot openings.

10. The process of Claim 9 wherein the slot openings are reduced by reforming the stator teeth tips radially outward to return the stator bore to a cylindrical form.

11. The process of Claim 9 wherein the step of enlarging includes radially supporting stator teeth between the teeth tips and deforming adjacent teeth tips.

12. Apparatus for assembling coils into the slots of stators and the like comprising:
a stator bore support for engaging and supporting a stator core;
means for forming stator teeth tips radially inward to conform the teeth to the bore support;
a plurality of generally circular disposed parallel extending blades for supporting coils and a stator core;

means movable along the blades for forcing coils along the blades and into stator core slots; and means for reforming stator teeth tips radially outward to provide a cylindrical bore stator.

13. The apparatus of Claim 12 wherein each blade engages a corresponding stator tooth with gaps between adjacent blades aligned with corresponding stator slots, each blade having a pair of elongated depressions for accepting the respective formed stator teeth tips, and a pair of ribs outside the depressions for spanning the corresponding tooth.

14. The apparatus of Claim 12 wherein the means for forming includes a number of punches each disposable in a stator slot, and means for forcing each punch toward the corresponding stator teeth tips.

15. The apparatus of Claim 12 wherein the means for reforming includes a plurality of cylindrical rollers for simultaneously engaging the stator bore to rollingly traverse the bore interior and displace the stator teeth tips radially outwardly.

16. The apparatus of Claim 13 wherein the formed stator teeth tips are simultaneously forced radially outwardly to the positions they occupied prior to forming.