US2221687A - Transformer assembling method and apparatus - Google Patents

Description

Nov. 12, 1940. s. qEvAr s' I 2,221,687

TRANSFORMER ASSEMBLING Margo]; AND APPARATUS Filed Aug. 23; 1939 Invehto'r: Sidle 0. Evans,

' Hi: XXttcwwwey Patented Nov. 12,1940

PATENT OFFICE msnsroamza assnrmnmc m'zrnon Amp APPARATUS I Sidiey 0. 1mm, Pittsfleld, m, assignor to Gen. eral Electric Company, a corporation of New- York- Application August 2a, 1939, Serial No. 292,115 I h 3 Claims. -(c1. 242-4) My invention relates to methods and apparatus for assembling transformers, reactors, and other stationary induction apparatus and concerns particularly apparatus of the wound-strip-core type. 6 In United States Patents 2,160,588Granfleld 'Electro-magnetic induction apparatus and methd of making the same, and 2,160,589-Grah- 'fieldApparatus for makingstrip wound magnetic cores-there are disclosed methods and apl0 paratus ,for applying magnetic cores of the wound-strip type to conductive winding structures. One of the steps in the Granfleld process involves the unwinding of a coil of magnetic strip into a larger loop, which larger loop is passed through the window-of a conductive winding in order that the strip may be unwound from the original coil and simultaneously rewound around the. conductive-winding leg, it being important to avoid excessive str 0! the magnetic strip material. Excessive tortion of the larger loop must'accordingly be avoided. In certain types of conductive-winding structures; such as socalled two-group or three-legged conductivewinding structures and winding structures hav--- ing more than two groups and more than three legs, the space into which such a larger loop may be passed while winding it around the center leg of the winding structure tends to become rather restricted so as to make it diflicult to pass the larger loop around the center leg of the winding structure without excessive distortion of the larger loop.

It is an object of my invention to provide arrangements for avoiding such distortion and to provide modifications. in the arrangement oi the aforesaid Graniield patents to'adapt Granflelds core-applying method to two-unit three-legged winding structures and winding. structures having more than two units or more than three legs.

40 Other and further objects and advantages will become apparent as the description proceeds.

My invention may be understood more readily from the following detailed description when considered in connection with the accompanying drawing and those features oi. the invention which are believed to be novel and patentable will be pointed out in the claims appended hereto.

In the drawing, Figure lis a diagram illustrating one step in the process of app y n a wound core to a conductive winding structure in accordance with one embodiment of my invention.

Figure 2 is a diagram illustrating a more advanced step in the process represented in Figure 1. Figure 3 is a diagram representing-a still more advanced step in the same process, showing the beginning of the application of the strip to the center leg of a three-legged or two-unit conductive-winding structure. Figure 4 is a view partially insection. of the completed transformer illustrating the final step in the process represented in Figures 1 to 3 inclusive. Figure 5 is a diagram illustrating a step in the beginning of apro'cess constituting .another embodiment of my invention. Figure 6 is a diagram illustrating a more advanced step in the process represented in Fig- 10 ure 5, and illustrating also a form of machine which may be employed in carrying out the. process, and Figure 7 is a diagrammatic representation of a machine which may be employed in carrying out theprocessnof Figures 1 to 4, inclu- 1 sive. Like reference characters are utilized throughout the drawing to designate like parts.

My invention is concerned with the application of a hollow cylindrical, flatwise spirally wound core or magnetic strip material to a con- 20 ductive-winding structure of the three legged or radial type in which there is more than one group of coils. Conductive windings of this type have usually a center leg which is common to all of the groups of coils and around which-the mag- 25 there are only two coil groups I! and." radiat- 35 ing from the center so that a three-legged wind ing structure results consisting of the center leg Ii and the outer legs I and IE; but if additional coil groups were employed there would be so many additional outer legs radiating from a center leg, T

such as the leg Ii, which would include one side of each or the coil groups. In the apparatus illustrated, taking the form of a transformer, each coil group consists of a pair of concentric windings It and ILone surrounding the other, and 5 one being the primary winding and the otherheing the secondary winding. It will be under! 'stood, of course, that this method of assembly may be used equally well for conductive wind-r ings which are of the interleaved or pancake typ 50 It will be observed also that the cross-sectional shapes oi the componentwindings are so chosen that when the various coil groups are fitted-together, a center. leg II is formed which is of a. shape tending substantially to fill a circular open- I- ing IS in the magnetic core so that the mean] The larger loop 2| is thereupon placed over the length of turn of core still is as short as possible, with a resultant saving in steel. In the case illustrated, theceuter leg H has a cruciform section.

A step in theprocess described in the Granfleld Patent 2,160,588 involves the simultaneous unwinding of a coil of magnetic strip material,

such as the coil ,20 in Figure 1, the rewindingof the material into a larger loop, such as the loop 2| in Figures 1 and 2, the larger loop being wound about the conductive winding leg in the arrangement described by Granfleld. It will be observed, however, that in connection with a conductive winding, such as that shown in my drawing, it would be difficult to pass a larger loop, such as the loop 2|, around the center leg- .without distortion thereof owing to the restricted space provided by the winding windows 22 and 2t (Fig. 3') owing to the spacial relationship betweeh. the center leg I and the outer less It and I5. In order to .avoid distortion of the larger loop 2|, and in order to permit the conductive winding structure to be fully assembled with the center leg completely taped and insulated before the application of the core strip is begun, I increasethe number of steps in the process shown in the Granfield patents,.but I divide the step of forming the larger loop around the conductive winding leg into-two steps. I first form the larger loop, and after it has been formed, 1 rewind the materialfrom the larger loop into a smaller loop around the center leg of the winding,

The complete process may be described more in detail as follows. As in the arrangement de-\ scribed in the Granfield patent the actual process of application of the coil of strip to the conductivewinding structure begins after a coil of strip 20 has been formed, which is in the shape of a hollow cylinder composed of a plurality of turns of strip material tightly wound flatwise spirally and having the exact shape and size which the finished core I9 (Figure 4) is to have in the completely'asse'mbled apparatus. It will be under- 45 stood that this initial coil of strip 20 hasv been subjected to suitable heat treatment-so as to reduce its watt losses and magnetizing current,

to remove strains within and beyond the elastic limit and leave it with a permanent set, tending to retain it in the shape and size shown. The coil ofstrip 20 is unwound into a larger loop2l by drawing off the length of strip from the outside turns of the coil 20 and bringing the end 20 of the strip backupon the next lower adjacent layer of strip, as illustrated in Figure l. The end of the strip 2% is preferably secured to the adjacent layer of strip in some suitable manner, 'as by spot welding in order to prevent collapse of the larger loop, since the coil, aspreviously explained,

has apermanent set tending to return it to the diameter of the successive turns in the coil 20. The originalcoil 20 and'the: larger loop 25 are rotated so as to transfer the material from the coil 20 to the larger loop 2| and one will observe 5 that the turns are in the same sequence in the coil 20 and the larger loop 2i. If desired, a pair of rollers 2s and 2e, biafsed toward each other so as to engage the strip frictionally may be employed' for performing the unwinding and re- 70 winding operation. It will be unde that suitable driving means, not shown, may be. con- 'nected to one or both of the rollers iii and 26.

After very nearly all of the material has been transferred to the larger loop 2 i the larger loop conductive winding structure 21, as, illustrated in Figure 3, or vice v'ersa,such a winding structure may be placedwithin the larger.loop II, The inner end 28 of the strip of material in the larger loop 2| is allowed to loop around the center leg I I of the conductive winding structure .21 and the direction of rotation of the larger loop 2|- is then reversed so that the smaller loop 29 is permitted to wind around the center leg I I. The

' simultaneous rotation of the larger loop 2| andthe smaller loop 20 causes the smaller loop 29 to circle around the leg building up progressively with material from the innerl yer of the larger loop 2| passing to the outer! yer of the smaller loop 28. After all of the material in the larger loop 2| has been transferred to the smaller 'loop 20, a core, such as the core i0, shown in Figurei'i, is formed. It, will be understood, 0! 'course, that if the loop 2| is turned over 180 de- 20 grees around one of its diameters, in going from the step represented in- Figure 2 to that repre-'- sented in Figure 3, it will be unnecessary to reverse the direction of rotation. of the driving . rollers 25 and 26. Owing to the frictional engagement' between turns and with supporting structure, not shown, there may be a tendency for the turns of the smaller loop 20 not to return completely to the original shape and diameter of the corresponding turn in the original coil. of strip, and it may be necessaryto overcome friction and tightenthe turns of strip in the smaller loop 29 by hand or by means of col-. lapsing rollers, such as the rollers 23 and 24, illustrated in Granfield Patent 2,160,589. This last step in the process, however, not being peculiar'to my invention, need not be described or illustrated in'detail.

It will be understood that the conductive winding structure 2'! is supported in the position indicated by suitable means, not shown, and that the process may be carried out with the axes of the loops 2| and 29 eithervertical or horizontal, in which latter case the roller 25, together with guide rollers 30 and 8| would serve as a support for the strip material in the loop 2|. The guide rollers 30 and 8|, together with an additional guide roller efi serve to prevent collapse of the larger loop 2|. 0n the other h nd, if 'the process is carried out with the axes of he loops II and 29 vertical, a suitable table, not shown, will'be provided for the support ofthe loop 2|, asdisclosed in the Granijield Patent 2,160,589, and a slot in the table will be provided to receive the conductive structure 21.

In connection with the assembly of apparatus r. of relatively large size, the core material tends to become relatively heavy and the friction of the strip 2| upon a supporting table may become ex oessive when the operation is performed with the axis of the loop 2| vertical. In order to overcome suchfriction and cause the loops 2| and 29 to be rotated more easily.v and with equal peripheral velocities, the machine disclosed in Figure '1 may be employed. In Figure 7 the apparatus is seen from the top. Planes through the edges of strip 7 in the *iarger and smaller loops 2i and 29 are horizontal. Relatively long cylindrical rollers.

88 are provided for the support of the strip material and guide rollers u are provided to guide the l rger. loop 2| upon the rollers .33 and prevent premature collapse of the larger loop 2|. The rollers 33 have, as indicated, horizontal. axes'and are radially disposed about the center leg ll,

to support the smaller loop 29 and extending sufficiently far outwardly to support the larger loop 2|. Although the rollers 33 need be continuous from the inner ends supporting the smaller loop 29 to the outer ends supporting the larger loop 2| they may conveniently be continuous since in this manner assurance is provided that the peripheral velocities of the inner and outer legs will be the same and material will be fed to the inner loop as fast as it is withdrawn from the outer loop. In connectionwith strip exceptionally sensitive to strain, it will, of course, be advantageous to have the supporting rollers 33 at the positions 35, at the left-hand'side, continuous in order that the portion of strip leaving the outer loop and approaching the inner loop may have support. The rollers 33 are, of course, rotatably mounted upon suitable bearings which need not be shown, and,in order to avoid manual labor, motor driving means, are provided for rotating all of the rollers 33, preferably at uniform speed, any desired mechanical connection or gearing being used for this purpose.

For example, a driving motor 4| may be provided connected to the shaft of one of the rollers 33. For causing all the rollers to be driven uniformly, there may be provided a ring gear 42 (shown fragmentarily) engaging pinions 43 forming extensions of the rollers 33.

Although I have shown in Figures 1 and 3, and have explained in connection therewith a core applying arrangement in which the larger loop 2| entirelysurrounds the multl-unit conductive winding structure 21, it will be understood that my invention is not limited thereto, and includes any arrangements in which an intermediate step in the process consists of encircling two or more of the legs of the conductive winding structure, but not necessarily all of the legs of the winding structure, as shown in Figure 3. A subsequent step consists of rewinding the strip around the winding leg which is tobe'linked by the core in the finally assembled apparatus. For example, as illustrated in Figure 5, the original coil of strip 20 may be unwound and simultaneously rewound into a larger loop 36 which does not surround all three of the legs ll, 14 and I5 of the conductive winding structure 21, but instead surrounds only the center leg H and one of the outer legs l5,

and passes through the winding window 23. In

this case, of course, as the coil of strip 29 is unwound it must simultaneously be rewound into the winding structure 21, and-a larger loop cannot subsequently be placed around the winding structure 21, as in Figure 3. As explained in connection with Figure 2, however, the outer end 24 of the strip is preferably fastened down to the adjacent layer of strip and the rotation of the rollers 25 and 26, the coil 26, and the loop 36 are carried out until all of the material has been transferred to the larger loop 36. Thereupon, the inner end 28 of the strip is led around the center winding leg H and allowed to circle therearound forming the smaller loop 29. The direction of rotation of the driving rollers 25 and 26 and the larger loop 36 is then reversed, causing the ma-- terial from the inner layer of the larger loop 36 to be transferred to the outside of the smaller loop 29, simultaneously rotating the smaller loop 29 and causing it to build up to form the finished core [9, as explained in connection with Figures 3 and 4.

If desired, a machine similar to that shown in Figure 7 may be employed for causing the rotation of the larger and smaller loops 29 and 86 of Figure 6 and supporting them during the winding process. In this case, however, two sets of rollers will be required since the loops 29 and 36 are not concentric. For example, a set of rollers 31 and 38 may be provided for supporting and rotating the smaller loop 29, the rollers 38 serving also to support and rotate the larger loop 36, and a set of rollers 39 may be provided -help-' ing to support and rotate the larger loop 36, all of the rollers preferably being driven at substantially the same peripheral speed. As in Figure '7 the rollers 31, 38 and 39 have horizontal axes of rotation. The gripping or driving rollers 25 and 26 may either be retained or omitted, as desired in the arrangements of both Figure 6 or '7. I'f're-' tained, their peripheral speed is preferably substantially. the same as that of the rollers 33, 31, 38 and 39.

For removably supporting the winding structure 21 during rewinding and winding operations, suitable adjustable clamps may be provided similar to the clamps 31 and 38 of Granfield Patent 2,160,589, for example. As shown in Figure 5, the winding structure 21 rests between rubbercovered rollers 40 of the lower clamp and similar rollers of an upper clamp, omitted from the drawingfor the sake of clarity. -A similar adjustable supporting mechanism may be employed for the winding structure in the assembling machine of Figure '7, but is not shown in either Figure '7 or 6 to avoid confusion in the drawing. It will be understood that the core-supporting rollers 33, 31 and 38 are removable to'permit mounting and removing the winding structure 21.

Ihave herein shown and particularly described certain embodiments of my invention and certain methods of operation embraced therein for the purpose of explaining its principle and showing its application but it will be obvious to those skilled in the art that many modifications and variations are possible and I aim, therefore, to cover all such modifications and variations as fall within the scope of my invention which is defined in the appended claims.

What I claim as new and desire to secure by Letters Patent of the United States is:

l. A method of assembling a wound strip, magnetic core with a two-group conductive-winding structure having a center leg, which method comprises the steps of forming'a strip of magnetic material into a hollow cylinder of turns spirally wound flat-wise with a permanent set in sub-- stantially the shape and size which the core is to have in the assembled apparatus, unwinding said cylinder into a larger loop with the turns in the same sequence, bringing said larger loop en tirely around a conductive winding structure with which the core is to be assembled, looping the inner end of said larger loop of strip around the center winding leg to form a smaller loop encircling the said leg, and'rotating the loops of strip to transfer the strip to the smaller loop around the winding leg.

2. A method of assembling a flatwise spirally wound hollow cylindrical coil of magnetic strip with a two-group conductive-winding structure having a. center leg and a pair of winding windows, which method comprises the steps of unwinding the strip from the coil and simultaneously rewinding it into a larger loop passing through one of the winding windows and surrounding two of the legs of the conductive winding as well as the axis of the coil, rotating the '3 coil and loop to transfer the strip materialfrom the outside of the coil to the inside of the larger loop, until all of the strip material has been transferred to the larger loop, looping the inner end of the larger loop around the center leg of the conductive winding structure to form a smaller loop and reversing the direction of rotation of the larger loop to transfer the strip mate-- rial from the inside of the larger loop to the outside of the smaller loop and thereby form a magnetic core surrounding said center winding leg.

3. A method of assembling a flatwise spirally wound hollow cylindrical coil of magnetic strip around a leg of a conductive winding having a plurality of legs and winding windows, which method comprises the steps of bringing a rela-- tively large coil or loop of magnetic strip around a plurality of the legs of the said conductive winding structure including said first-mentioned leg, looping the inner end of the large loop around said leg of the conductive winding structure through two adjacent winding windows to form a smaller loop and rotating the large loop, together with the smaller loop, in such a direction as to transfer the strip material from the inside of the large loop to the outside of the smaller loop and thereby form a magnetic core surrounding said first mentioned winding leg.

4. A machine for applying a wound-strip magnetic core to a conductive-winding structure consisting of two or more groups and having a center leg, said machine comprising means for supporting such a multi-group winding structure with its center leg vertical, a plurality of cylindrical rotatably mounted rollers with axes in a horizontal plane and radially disposed with respect to the position in which the center leg is supported and of suflicient length to support both a loop of magnetic strip surrounding the center leg of the conductive winding structure and a loop of such strip entirely surrounding the conductive winding structure, vertical guides positioned to prevent collapse of the larger loop upon the smaller, and means for rotating said rollers.

5. A machine for applying a wound-strip magnetic core to a conductive win'ding structure consisting of two or more groups and having a center leg, said machine comprising means for supporting such a multi-group Winding structure with its center leg vertical, a pluralityof cylindrical rotatably mounted rollers with axes in a horiof such strip entirely surrounding the conductive winding structure.

6. A machine for applying a wound-strip magnetic core to a multi-group conductive winding structure having a center leg, said machine comprising means for supporting such a multi-group winding structure with its center leg vertical, a set of cylindrical rotatably mounted rollers with axes in a horizontal plane radially disposed with respect to the position in which the center leg is supported and extending relatively close thereto, a set of rotatably mounted rollers with axes in the same horizontal plane radially disposed about a point off center with respect to the position in which the center leg is supported and of suflicient length to support a relatively large loop of magnetic strip surrounding a plurality of the legs of the conductive winding structive, and means for rotating loops ofmagnetic strip material supported by said rollers to transfer material from the inside of the large loop to the outside of a smaller loop carried by the first set of rollers.

7. A machine for applying a wound-strip mag-v netic core to a multi-group conductive winding structure having a center leg, said machine comprising means for supporting such a multi-group winding structure with its center leg vertical, a set of cylindrical rotatably mount-ed rollers with axes in a horizontal plane radially disposed with respect to the position in which the center leg is supported and extending relatively close thereto,

a set of rotatably mounted rollers with axes in the same horizontal plane radially disposed about a point ofi center with respect to the position in which the center leg is supported and of sufliclent length to support a loop of magnetic strip surrounding a plurality of the legs of the conductive winding structure, and means for rotating said rollers with uniform peripheral velocities.

8. A machine for applying a wound-strip magnetic core to a multi-group conductive winding structure consisting of a plurality of Winding legs including a center leg, said machine comprising means for supporting such a multi-group winding structure with its center leg vertical, cylindrical rotatably mounted rollers with axes in a horizontal plane, said rollers being so positioned in relation to the winding supporting means as to be adapted to support a loop of mag netic strip material surrounding only said center leg, and to. support a loop of such material surrounding a plurality of legs on the winding structure including said center leg, respectively, and

means for rotating said rollers with uniform peripheral velocities.

SIDLEY O. EVANS.

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