US3491437A - Scrapless method of stamping e laminations - Google Patents

Description

Jan. 27, 1970 E. R. SMALL 3,491,437

' SCRAPLESS METHOD OF STAMPING E LAMINATIONS Filed May 6, 1968 m $33 2/ 5"? I 5 .I- J "J7 T: J7a 19 2'7 \26 25 mscmueee TO FORM LAYERS DISCHARGE TO FORM LAYERS (STACK) or UNNOTCHED E'S (fSTACK) OF NOTCHED ES E LAMINATION I IE CORNER BY fi 957120]! flk yja j POBERTLK AT'TY United States Patent 3,491,437 SCRAPLESS METHOD OF STAMPING E LAMINATIONS Edward Randel Small, Fullerton, Calif., assignor to Allegheny-Ludlum Steel Corporation, Pittsburgh, Pa., a corporation of Pennsylvania Filed May 6, 1968, Ser. No. 726,939 Int. Cl. B26d 1/00 U.S. Cl. 29-602 4 Claims ABSTRACT OF THE DISCLOSURE The present invention is an improvement upon an earlier invention relating to a scrapless method of stamping E laminations from an endless strip of metal. The pattern in this particular method involves stamping four 90 corners converging about a point at periodic intervals in such endless strip. Due to the lack of geometrical perfection of a 90 die corner (under magnification such a corner shows up as rounded rather than terminating in a sharp edge), small spurs or spines of metal from the strip are created where such 90 cuts occur. The invention herein disclosed contemplates the preliminary punching out of a small aperture in the metal strip at the regions where such right angle shapes cluster. The aperture is large enough so that there is no metal in the strip from which spurs may develop.

This invention relates to a scrapless method of stamping E laminations from an endless strip of laminations material. The invention to be hereinafter disclosed is an improvement upon the application of Donald 0. Schwennesen, Ser. No. 565,897, filed July 18, 1966, for a method of making laminations without scrap. In this application, assigned to the same assignee as the present application, a stamping pattern is disclosed wherein two rows of interlocked small Es on one side of an imaginary dividing line along a strip of metal is transversely aligned with two interlocked rows of large Es on the other side of said imaginary dividing line. All Es have end legs of equal width extending laterally from similarly dimensioned bases. The center leg for the ES is twice the width of the end legs. The lengths of the legs of the large Es are the same and are longer than the lengths of the legs of the small Es which are also the same. As more fully pointed out in said application (and to be disclosed in detail here),

the stamping pattern makes it possible to use the original strip metal completely without any scrap.

Scrapless stamping of lamination metal is particularly important in the case of the rather expensive nickel-bearing alloys used in such laminations. As an example, alloys containing about 80% of nickel are frequently used for laminations. Such alloys at the present time run about $3.00 a pound. It has generally been the practice for the industry to tolerate as much as 50% scrap loss. The recovery in the way of re-sale value of said scrap is' generally about 15% of the original metal price. The result is that in practice, stamped laminations of such nickel alloys may represent a cost of substantially $6.00 per pound. The tonnage involved in such lamination manufacture is substantial.

The stamping pattern disclosed and claimed in the aforementioned Schwennesen application is highly efficient and the application of the invention to production has resulted in great savings. In connection with the preferred stamping pattern, spurs may occur at points in the stamping pattern where a plurality of shear lines meet. These points occur, in the particular stamping pattern referred to, along the imaginary dividing line marking the length of an E lamination. Such spurs will occur on the outer corners of such laminations. This invention makes it impossible for 3,491,437 Patented Jan. 27, 1970 spurs to occur. The application of the invention results in the creation of some strip metal scrap in an amount which is so small (less than 1%) that for all practical purposes, Scrapless production of laminations is still true.

The spurs interfere with automatic or manual handling of laminations. In many instances, laminations are fed to automatic facilities for assembling laminations and windings to make transformers or chokes. Such automatic facilities require that the outer corners of the E stampings be smooth and free from spurs for successsful operation. This is also true of manual assembly of laminations and windings. While a spur as a rule is no longer than about one or one and a half mils (.001) it is enough to cause cuts in fingers. It is, therefore, of great practical importance to provide laminations free of spurs but stamped in accordance with the previously identified stamping pat tern.

The invention contemplates pre-punching small apertures through the endless metal strip along the imaginary dividing line in the stamping pattern at intervals corresponding to the length of an E base at the intersection of the transverse lines of metal shear and the imaginary dividing line. This removes the strip metal at regions which may be sources of spurs during the stamping or punching procedure.

For an understanding of the invention reference will now be made to the drawings wherein FIG. 1 is a plan view of a stack of E laminations from the inner rows of Es, the outer corners of the layers, each consisting of a small and large E, being notched.

FIG. 2 shows a plan view of a stack of E laminations, derived from the outer rows of Es and being free of notches. 7

FIG. 3 is an enlarged plan view of a length of lamination metal illustrating a stamping pattern in connection with which the invention is useful.

FIG. 4 is a plan view of a multi-station punching procedure utilizing the stamping pattern illustrated in FIG. 3, this view also illustrating selective discharge paths of the inner and outer E rows.

FIGS. 5a and 5b are greatly magnified details illustrating the problem encountered toward which the present invention is directed.

Metal strip 10 is endless and is of lamination metal whose overall width is designated as 11. Extending longitudinally of strip 10 is imaginary dividing line 12 between inner row 14 of successive small ES and inner row 15 of successive large Es, these two inner rows being disposed in back to back relation on opposite sides of imaginary dividing line 12. Interlocked with inner row 14 of small BS is outer row 16 of successive small Es, the outer edge 18 of this row constituting the outer edge of the strip. Similarly, inner row 15 of successive large Es is interlocked with outer row 17 of successive large E5, the outer edge 19 of the outer row constituting the remaining edge of endless strip 10.

It is understood that the showing of FIG. 3 is illustrative of a stamping pattern. At spaced intervals along imaginary dividing line 12, and meeting the same at right angles thereto, are transverse shear lines 21a and 21b. Shear line 21a extends across inner row 14 of small Es while shear line 21b extends across inner row 15 of large Es. While shear lines 21a and 2112 should form one continuous line extending across imaginary dividing line 12 at points 22, this does not actually occur in the idealized geometry of the stamping pattern. The actual shearing of the metal about point 22 will occur at different times. Transverse shear lines 21a and 21b do not form one continuous shear line with real dies (although in transverse alignment) and do not intersect imaginary dividing line 12. This is due to the lack of geometrical precision of a die cutting edge (shown in FIG. 5 as a rounded tip rather than a true point).

Dividing line 12 is imaginary only as part of a stamping pattern considered with respect to the endless strip prior to stamping or punching. Actually the separation between the back to back Es in inner rows 14 and 15 does occur along dividing line 12 although it is understood that separation along line 12 occurs at any one time only between adjacent points of intersection 22. Simillarly adjacent Es along the outer rows are sheared at lines 23:: and 23b and this may occur either simultaneously or successively as will appear later in connection with the stamping procedure.

Between adjacent interlocked roWs 14 and 16 of small Es is a square wave line of shear 25. Similarly interlocked large B rows 15 and 17 have a square wave line of shear 26. The complete width 11 of strip consists of the length of a leg from the large E plus the length of a leg from the small E plus four times the width of the base or back portion of an E (this being that portion bordering on dividing line 12 or outer strip edges 18 and 19). In the stamping pattern, the width of an end leg is equal to one half of the width of a center leg for both large and small Es. The widths and lengths of the base of all the ES are similar.

Geometrically, intersection points 22 of shear lines 21a, 21b and dividing line 12 should have no finite dimensions. In practice, the lack of absolute perfection of the 90 angles clustered about points 22, particularly the minute curvature of the die edges, result in spurs created near points 22 during stamping. Instead of two die edges meeting at a theoretical point, the die edges (as seen in plan) meet to form a rounded curve. This becomes visible under magnification. In accordance with the present invention, the stamping pattern illustrated in FIG. 3 is modified from that disclosed in the Schwennesen application previously identified by having small region 22a about each point 22 where metal is punched out about each imaginary point 22. The shape of aperture 22 may vary but a small circular aperture is preferred. The diameter of such aperture is not critical and should be large enough to prevent the formation of spurs. In practice, apertures 22a are too small to be used for piloting. For example, in an endless strip of metal having a width of one inch, an aperture having a inch diameter is ample. There is no particular relation between aperture diameter and strip width and it is not necessary to change the aperture diameter to match any strip width. It is apparent, however, that the spacing between adjacent apertures 22 along strip 10 may vary with strip width due to geometrical considerations.

Apertures 22 may ordinarily be too small to function as pilot apertures for feeding strip 10 through a press. However, it is possible to enlarge apertures 22 suificiently for pilot purposes. In such case, depending upon strip width, the metal punched out will be scrap and the percentage of scrap may rise to a small but appreciable value. The punching of each aperture 22 will occur at a station ahead of any E punching station.

For pilot purposes, the arrangement disclosed in the Schwennesen application, wherein windows created when one or more Es are punched out is used, functions satisfactorily.

Referring now to the procedure for stamping or punching out Es in accordance with the stamping pattern illus trated in FIG. 3, FIG. 4 illustrates in diagrammatic form a stamping pattern for applying the invention. The gen eral stamping or punching procedure is similar to that diss closed in FIG. 4 of the Schwennesen application. As illustrated here in FIG. 4, seven stations for operating on the metal strip are illustrated. It is understood that in a progressive die, the metal will be fed intermittently through successive stations.

Station 1 is where aperture 22a is punched along imaginary dividing line 12 of strip 10. It is understood that the actual punching station extends somewhat beyond the regions where aperture 22a is punched out, the actual punching occurring at a desired location within station 1. Strip 10 is fed progressively to station 2, the amount of travel of the strip being accurately controlled once punching has been initiated, so that aperture 22a is moved into station 2. At station 2 a suitable punch cooperating with a suitable die on opposite sides of strip 10 will punch out inner large E 150. When E 15a is discharged after the punching operation, originally round circles 22a be come mutilated to notches. Thus, circular aperture 22a when it first reaches station 2 (at the right end of the station) will have a tiny substantially portion of the circle removed. At the far end of station 2 (between stations 2 and 3), the notch is still further reduced from about 270 to substantially 180.

As a strip progresses to station 3, pilot member 25 will engage the opposite sides of the window where the full width center leg of lamination 15a was originally located. Proceeding to station 4, small inner E lamination 14a is punched out. Inner E rows 14 and 15 now have been eliminated by removal of the inner E laminations on opposite sides of dividing line 12. Pilot member 26 in station 4 is similar to pilot member 25 in station 3 and cooperates with the outer large Es of row 17 in the same manner as pilot member 25.

At station 5, pilot member 27 is provided extending between transversely aligned spaces between adjacent legs of the BS in outer rows 16 and 17. This pilot member 27 extends across the prolongation of dividing line 12 which by now has disappeared due to the absence of metal from the rows abutting dividing line 12. Suitable guides may be provided adjacent outer edges 18 and 19 of the original strip metal for properly positioning outer E rows 16 and 17 in predetermined lateral position. The guided metal strips making up rows 16 and 17 of the outer Es may be severed or sheared into individual Es 16a and 17a at the same station or at successive stations.

Es 14a and 15a have their outer edges (the edges at the ends of the base or back of each E originally along dividing line 12) notched. Circular aperture 22a is large enough so that removal of strip metal about point 22 will eliminate the possibility of spurs 28 being generated during stamping. Notched Es 14a and 15a are discharged from the press to form a lamination layer wherein the legs of the two Es extend toward each other in abutting relation. Preferably the Es in adjacent lamination layers are staggered or reversed. One layer has small E 14a and large B 15a as illustrated in full lines in FIG. 1, the small B being above the large B in the plan view. The adjacent layer will have this relationship reversed so that the small B will be below the large E, as illustrated in dotted lines in FIG. 1. This staggering is well-known in the art and the means for discharging such laminations to produce such a stack of lamination layers is well-known. It should be noted that in FIG. 1, Es 14a and 15a have theirouter edges notched, each such notch having the shape of a quadrant of circular aperture 22a.

Similarly Es 16a and 17a are discharged from the press also in position to form a layer with legs extending toward each other and adjacent layers being staggered to alternate the long and short legs in a stack. These E layers, illustrated in FIG. 2, are free of notches.

The separation of the notched and un-notched laminations as illustrated here may or may not be desirable, depending upon the customer's wishes. It is clear that if notched and un-notched Es are mingled, then reversing or staggering the position of adjacent layers is greatly simplified. Thus, the notched Es when discharged from stations 2 and 4 may travel down a chute and end up with legs facing each other. The BS from station 7 (or 6 and 7, if necessary) may be arranged to travel to the same stack as from stations 2 and 4 in which case alternate layers will be notched and Lin-notched.

The advantages of the stamping pattern and procedure disclosed and claimed in the Schwennesen application are retained in the present application irrespective of the manner in which the Es are assembled (having all notched Es in one stack and un-notched Es in another stack or alternating notched layers with un-notched layers). In either case, a stack or two stacks of laminations will have adjacent layers from metal whose position in the original strip is also adjacent along the length of such strip metal and not indiscriminately mixed.

The tiny pieces of metal punched out of strip will be discharged and theoretically will constitute some scrap. In practice, however, the present invention may be easily applied to the procedure and stamping disclosed in the Schwennesen application, it only being necessary to add a punching step corresponding to station 1 in FIG. 4 to the progressive stamping procedure disclosed in the Schwennesen application.

What is claimed is:

1. In the art of making transformer lamination from a continuous strip of magnetizable material, wherein a complete lamination layer consists of large and small opposed complementary Es, each E having a base and legs extending laterally from the front edge of the base, each outer leg having a width equal to half the width of the center leg and being equally spaced therefrom, the legs of a large E being equal in length, the legs of a mating small E being equal in length, the bases of both Es being equal in width and length, a pair of complementary Es in a lamination layer being disposed with their legs extending toward each other in abutting relation and the bases being parallel with the rear of each base being on the outside of one lamination layer; said continuous strip of material having its width equal to two component widths, one component width being equal to twice the width of the base of one E plus the length of the leg thereof, the other component width being equal to twice the width of the base of the other complementary E plus the length of the leg thereof, the width of such strip being constant and an imaginary dividing line between such component widths being straight and extending longitudinally of the continuous strip parallel to the strip edges; there being on one side of such dividing line said one component strip portion accommodating a pattern having two rows of interlocked equal Es, the rows extending longitudinally of the strip and the ES of the outer row having their bases extending continuously along the strip edge and the bases of the Es in the inner row extending continuously along the dividing line and all the legs extending transversely of the strip; said other component strip portion accommodating a pattern having two rows of complementary equal Es arranged in the same manner as in the one component strip pOrtiOn, the E pattern being such that the legs of the Es in the two outer rows extending along the outer edges of the entire magnetizable material strip extend toward each other in transverse alignment; the inner rows of Es having their legs aligned but extending away from each other, the method which (b) stamping, from one large inner E row and one small inner E row on said strip, one large B and one small E, originally in transverse alignment on said strip with the transverse ends of said stamped Es terminating at said small apertures to leave Es in the remaining two outer rows attached to each other in succession,

(c) piloting the strip metal through successive stamping stations by pilot members extending through the strip metal at regions where metal has been removed,

(d) shearing Es from the remaining outer rows along transverse lines coincident with the positions of the ends of the original inner row of E5,

(e) controlling the discharge and stacking of stamped Es so that a small E and complementary large E, originally transversely aligned in the original strip are paired to make a lamination layer.

2. The method according to claim 1 wherein the Es from the inner rows are discharged so that they are paired to make one lamination layer, such layer having the base ends of the ES notched where the original strip metal had been apertured, guiding such notched E layers for stacking, discharging the BS from the outer rows so that they are paired to make an nn-notched lamination layer and guiding such un-notched layers for stacking.

3. The method according to claim 1 wherein stamping of the large and small Es of the two inner rows occurs at two separate stations with an intervening station therebetween, and wherein piloting occurs in the large B windows of the inner row at said intervening station and at the adjacent station where the last inner row E is stamped, said piloting for both large and small outer row Es occuring simultaneously at an additional station prior to the shearing of the outer row Es, said original strip apertures each having a diameter just large enough so that departures from perfection at the intersection of lines of the imaginary dividing line and the lines defining the ends of the inner row Es will not result in creation of spurs of strip metal at the corners.

4. The method according to claim 3 wherein one large and one small E from the inner rows are discharged so that they are paired to make one lamination layer, said layer having the base ends of the ES notched where the original strip metal had been apertured, guiding such notched E layers for stacking, discharging the Es from the outer rows so that they are paired to make an unnotched lamination layer and guiding such layers for stacking.

References Cited UNITED STATES PATENTS 509,770 11/1893 Scott 29609 X 1,962,431 6/1934 Daley 83-41 X 2,630,175 3/1953 Dickerman 834l JOHN F. CAMPBELL, Primary Examiner CARL E. HALL, Assistant Examiner US. Cl. X.R.

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