US3072001A - Methods of and apparatus for cutting strip material - Google Patents

Description

R. F. HERR METHODS OF AND APPARATUS FOR CUTTING STRIP MATERIAL Filed March 28, 1957 4 Sheets-Sheet l INVENTOR. RICHARD E HERR ATTORNEY R. F. HERR Jan. 8, 1.963

METHODS OF AND APPARATUS FOR CUTTING STRIP MATERIAL 4 Sheets-Sheet 2 Filed March 28, 1957 INVEN TOR. RICHARD F HERR Arronusv Jan. 8, 1963 R 3,072,001

METHODS OF AND APPARATUS FOR CUTTING STRIP MATERIAL Filed March 28, 1957 4 Sheets-Sheet 5 IE1 INVENTOR.

' RICHARD F HERR Q Q ATTORNEY an. 1963 R. F. HERR 3,072,001

METHODS OF AND APPARATUS FOR CUTTING STRIP MATERIAL Filed March 28, 1957 4 Sheets-Sheet 4 INVEN TOR. RICHARD F HERR United rates Fatent Q a 3,072,0ll1 METHODS OF AND AIIARATUS FGR CUTTING STRIP MATERIAL Richard F. Herr, (Icrtiand, ()hio, assignor to The Herr Equipment Corporation Filed Mar. 28, 1957, ser. No. 649,222 1 Claim. (El. 83-147) The present invention relates to material cutting, more particularly to methods of and apparatus for severing strip material to form transformer laminations, and the principal object of my invention is to provide new and improved methods and apparatus of the character described. This application is a continuation-in-part of my co-pending application Serial Number 431,551, filed May 21, 1954, and issued June 3, 1958, as Letters Patent 2,837,159.

In cutting laminations for use in building large electrical transformers, several diflicult problems are presented. One of the problems is due to the fact that the abuttin edges of respective adjoining laminations must fit together as nearly perfect as possible in order to provide an efficient, quiet transformer. It will be appreciated that cutting the laminations from relatively thin strip with the requisite degree of accuracy, particularly when each lamination may be of considerable length, is extremely difiicult.

Moreover, the strip material from which the laminations are cut is very expensive since it is made by a special process to provide certain magnetic properties. Accordingly, when cutting transformer laminations, scrap must be held to an absolute minimum since such scrap results in losses which are quite high in view of the large tonnages of laminations which are cut.

One of the prior art solutions to the problem of minimizing scrap, particularly when cutting keystone shaped laminations, is mounting one or more of the cutting dies so that it may be shifted to reverse its cutting angle relative to the longitudinal axis of the strip intermediate each cutting operation. However, this prior art solution has not been satisfactory since the use of shiftably mounted dies results in inaccuracies in cutting the laminations.

Another problem presented when cutting transformer laminations from material having special magnetic properties is that the material requires very delicate handling lest these properties be impaired. While it is possible to bend or otherwise stress the material to a certain degree, it is imperative that such stresses be held beneath a certain value. In certain cases, this value may, for example, be the elastic limit of the material; however, in other cases, this value may be materially less than the elastic limit.

While my invention is not limited to cutting transformer laminations from the strip material, it employs a novel method and apparatus which is particularly appropriate in solving the problems heretofore mentioned; and these advantages together with others will become apparent from a study of the following description and from the drawings appended hereto.

In the drawings accompanying this specification and forming a part of this application there is shown, for purpose of illustration, an embodiment which my invention may assume, and in these drawings:

FIGURE 1 is a side elevational view of apparatus embodying my invention,

FIGURE 2 is an end elevational view of the apparatus shown in FIGURE 1,

FIGURE 3 is an elevational view corresponding to the line 3--3 of FIGURE 1,

FIGURE 4 is an eleva-tional .view corresponding to the line 44 of FIGURE 1,

ances of the core being assembled).

Patented Jan. 8, IE63 FIGURE 5 is an enlarged sectional view generally corresponding to the line 55 of FIGURE 1,

FIGURE 6 is an enlarged broken fragmentary vieW generally corresponding to the line 65 of FIGURE 2,

FIGURE 7 is a still further enlarged fragmentary sectional View generally corresponding to the line 7-7 of FIGURE 6,

FIGURE 8 is a fragmentary sectional view drawn to the same scale as FIGURE 7 and generally corresponding to the line 88 of FIGURE 6,

FIGURE 9 is a fragmentary, exploded perspective view of a transformer core,

FIGURE 10 is a reduced size plan view illustrating the manner in which transformer laminations are cut from strip material by use of my invention,

FIGURE 11 is a view similar to FIGURE 10 but il lustrating a prior art manner of cutting transformer laminations from strip material,

FIGURE 12 is a fragmentary view, similar to FIG- URE 7, of another embodiment of the invention, and

FIGURE 13 is a diagrammatic view of a fluid circuit which may be employed to effect the desired operation of the embodiment shown in FIGURE 12..

Referring first to FIGURE 9, wherein a conventional transformer core is fragmentarily shown, it is to be understood that the present invention is particularly, although not necessarily, adapted to cut generally keystone shaped transformer laminations T which are adapted to be assembled together to form a transformer core.

When building a transformer core from laminations T (see FIGURE 9), it is to be understood that laminations will be clamped together to provide a rigid, unitary structure. Particularly in the larger sized cores, the laminations will have to be forced toward the position they will occupy since it is virtually impossible to insure that each lamination will he perfectly flat and without camber. However, in assembling the core, it is of the greatest importance that the force exerted on the laminations will be less than that which would impair their magnetic properties. In other words, the laminations will be clamped or otherwise urged together with the desirable end that the laminations will be flat and with their edges in alignment; however, the force exerted in so urging the laminations will be less than that which would impair their magnetic properties.

Stated another way and assuming, for the sake of illustration, that it is desirable for the laminations to be straight and flat, if they cannot be straightened and flattened by the use of the aforesaid limited force, they will be assembled by the use of such limited force in a somewhat than straight or flat condition (providing, of course, that in such condition the laminations will be sufiiciently straight and flat to meet the dimensional toler- My invention, as will later be described, is adapted to accurately cut laminations from strip material with a minimum of scrap (see FIGURE 10) and without impairing their magnetic properties.

As seen in FIGURE 1, the apparatus therein illustrated which embodies my invention comprises apparatus Ill which is adapted to cut the laminations T and apparatus 11 which is adapted to feed strip material 8 to apparatus it).

In the present embodiment, apparatus Iii) comprises a suitable press 12 raving the usual bed 13 and the usual ram 14 (see FIGURES 2, 7 and 8). The press 12 is herein shown to be of the inclined bed type for a purpose which will later become clear and secured to the bed 13 in spaced-apart relation by any suitable means are a pair of dies 15, s which are adapted to cut the strip material S.

As shown in FIGURE 7, die 15 comprises a lower plate 17 suitably secured to the bed 13 of the press 12 and an upper plate 18 guided for movement toward and away from the lower plate by the usual die pins 19. Springs 20 are positioned about the pins 19 and these springs yield-ably urge the upper and lower portions of the die apart as shown. The lower plate 17 of the die supports a stationary cutting blade 21 and the upper plate 13 supports a movable cutting blade 22. It will readily be apparent that as the die plates are moved together by the press ram 14, blades 21, 22 will sever the strip S.

Die 16 is similar to die 15 and similar parts are therefore identified by the same reference numerals but with the suffix a added. However, it will be noted that the cutting blades 21a, 22a of die 16 (see FIGURE 6) are arranged to square off a part of the end of the lamination so as to form it to the shape shown in FIGURES 9 and 10.

Means are provided for guiding the strip S intermediate the spaced-apart dies 15, 16 and as shown in FIGURE 7, such means may comprise a plate-like member 23 which extends between the lower plates 17, 17a of the respective dies and whose upper surface lies in the same plane as the upper surface of the respective lower plates.

A presser plate 24 is supported in spaced relation above the plate 23 and the respective upper surfaces of the lower plates 17, 17a of the dies and extends between the movable knives 22, 22a for a purpose to be shown. In the embodiment shown in FIGURES 7 and 8, plate 24 has guide pins 25 secured thereto and certain of these pins are slidable in respective upper plates of the dies and certain other pins are slidable in brackets 26 which depend from the ram 14 of the press. Springs 27 surround the pins 25 and such springs yieldably urge plate 24 toward plate 23 to clamp the strip therebetwcen when the ram 14 descends.

It will be noted that the springs 27 adjacent brackets 26 are spaced from the brackets in the position of parts shown in FIGURE 7. This space is provided so that all of the springs 27 will be compressed substantially simultaneously as the ram descends. Any suitable means may be employed to maintain the presser plate 24 spaced from the lower plate of the dies and the plate-like member 23 when the dies are open. For example, the pins 25 which are slidable in the upper plates of the dies may have heads 25a which seat in counterbores 25b formed in the respective upper plates of the dies.

For a purpose to be disclosed, it is desirable that the pressure exerted by plate 24 on the strip material S be adjustable; accordingly, it is contemplated in this embodiment that the springs 27 may be replaced with stronger or weaker springs, as the case may be, when it is desired to change the pressure. Another manner of varying the pressure might be to provide a shim (not shown) beneath each spring, which shims could be increased or decreased in thickness by adding or removing shim members as required.

Means are also provided for locating the edge of the strip S transversely of the dies 15, 16 and such means are presently shown to comprise a plurality of locating pins 28 positioned, in the embodiment disclosed, in a straight line along one side of the strip (see FIGURES 6 and 8). At the present time, three locating pins are employed, one adjacent each pair of cutting knives and one intermediate the dies. As will be understood, pins 23 are shiftable from the extended position shown in FIG- URE 8 wherein they are engageable with the strip S to a retracted position wherein they are clear of the strip and such shifting movement may be accomplished by any suitable means such as by means of fluid cylinders 29.

As also seen in FIGURES 6 and 8, means are provided for urgin the strip material toward engagement with each of the locating pins 28 and such means may comprise plungers 32) which are presently shiftable toward and away from the strip by means of fluid cylinders 31. As best shown in FIGURE 6, each plunger 30 is preferably in opposed relation with a respective pin 28 and each is movable by its respective cylinder to urge the strip material toward engagement with locating pins 28 to thereby apply a force edgewise of the strip tending to straighten it in the event it is cambered.

Cylinders 31 are preferably air actuated and are connected to a source of air pressure by means of a suitable valve (not shown) which controls flow of air thereto and therefrom. A pressure regulator valve (see FIGURE 6) is interposed in the line between cylinders 31 and the source or" air pressure to provide for adjustment of the pressure exerted by such cylinders for a purpose to be disclosed.

Operation of apparatus 10 thus far disclosed will now be described. Assuming that the respective upper and lower plates of the dies 15, 16 are separated as shown in FIGURES 7 and 8 and that the pins 28 are extended and plungers 30 retracted .as shown in FIGURE 8, a piece of strip 5 will be fed between the dies by means later to be disclosed.

The strip will be guided longitudinally on .one edge by means of the pins 28 and on the other edge by means of a shoulder 32 which extends upwardly from and forms a part of guide plate 23.

After the strip has been positione d between the dies, cylinders 31 will be actuated to move plungers 39 into engagement with the edge of the adjacent strip portion. This will crowd the edge of the strip portion toward engagement with each of locating pins 28, thus tending to remove, in the present case, any camber (or curvature) which may exist in such edge portion. It is to be understood that the regulator Valve in the line feeding cylinders 31 will be so adjusted that the force exerted by the cylinders on the strip portion will not exceed the force which will be exerted on the finished lamination at its assembly into the transformer core. By thus limiting the force exerted by the cylinders, the strip will not be stressed an amount whereinits magnetic properties would be impaired.

The press 12 will now be actuated to move ram 14 toward the bed of the press. As the ram 14 engages the respective upper plates of the dies 15, 16 and moves them downwardly toward their respective lower plates, presser plate 24 will first engage the adjoining side of the strip portion and firmly clamp such portion against the upper surfaces of the lower Plates of the dies 15, 16 and the upper surface of the plate 23. This will tend to straighten out the strip and insure accurate cutting thereof. It should be pointed out that springs 27 will be so chosen (or their effectiveness adjusted by means of shims or the like as before mentioned) that the flattening force exerted on the strip by pressure plate 24 will not exceed that which will be applied to the finished lamination at asembly into the transformer core to insure against an impairment of the laminations magnetic properties.

Continued movement of the ram 14 will cause each die to sever its respective end of the strip portion substantially simultaneously, and retraction of the ram will permit the dies to once again spring open. Pins 28 will then be retracted by cylinders 29 and this will permit the severed portion of strip (now out to form a lamination T) to fall from the dies since the press is of the inclined type. The pins 28 will then be extended by cylinders 29, the plungers 30 retracted by cylinders 31 and the strip fed between the dies once again.

In the embodiment shown in FIGURE 12 wherein similar parts are identified with the same reference characters but with the suffix 1) added, springs 27 and pins 25 have been replaced by fluid cylinders 161 carried by the respective upper die plates and the brackets which depend from the press ram. Cylinders 101 are preferably air actuated in a manner to be disclosed and each has a piston rod 102 whose free end is secured to the pressure plate 24b.

A constant air pressure is adapted to be maintained on cylinders 101 to resiliently maintain pressure plate 241) in the position illustrated and as seen in FIGURE 13, cylinders 101 are Connected to a source of air pressure via an air storage tank 103, a check valve 164 and a constant pressure regulator valve 105. Valve 105 will be so adjusted that the force exerted by cylinders 101, which force is in turn transmitted to the strip by means of pressure plate 24b when the press ram descends, will not exceed the force which will be exerted on the finished lamination at its assembly into the transformer core to thus insure against an impairment of the laminations magnetic properties.

As the press ram descends, pressure plate 24b will tend to flatten the strip until such flattening force exceeds the pressure exerted by cylinders 101. When this point is reached, piston rods 102 will be forced upwardly in their cylinders, against the air pressure within the cylinders, to absorb the overtravel of the press ram. The pressure exerted by cylinders 101 will be substantially constant and will not materially increase as the piston rods are forced upwardly since the relatively large storage tank 1493 will absorb the air displaced from the cylinders. Check valve 104, of course, will prevent flow of air in a reverse direction to the regulator valve Hi5.

Normally, if the strip were fed to the apparatus in the conventional manner, considerable waste strip would result (see portions W in FIGURE 11). However, the present invention reduces to a minimum the amount of scrap formed by turning the strip side for side about its longitudinal axis, intermediate each cutting operation.

Referring once again to FIGURE 1 wherein apparatus 11 for feeding the strip to the press 12 and for turning the strip in the manner mentioned is illustrated, it will be seen that such apparatus comprises a barrel-like structure 33 which is rotatably supported by flanged rollers 34 which are rotatably carried by respective roller supports 35.

As shown in FIGURES 1 and 4, strip feeding means 36 is suitably supported within the structure 33 and such means is preferably, although not necessarily, of the type disclosed in my co-pending application for Letters Patent, Serial Number 374,903, now US. Patent No. 2,819,070, issued Jan. 7, 1958, and U.S. Reissue No. 24,883, issued Get. 11, 1960, entitled Mechanical Movement Particularly for Feed Apparatus. Such feeding means comprises juXtaposed rolls 37, 37 which provide a pass for the strip material and which are adapted to be rotated by means such as disclosed in the aforementioned copending application to feed a predetermined length of strip through the pass. It should be sufficient to disclose thta the rolls 37, 37 grip the strip tightly and are adapted to be rotated a predetermined amount and thereafter stopped so as to firmly hod the strip in position. It is to be understood, however, that the particular feeding means shown is disclosed for purpose of illustration only and that any other suitable feeding means may be employed.

The strip S is adapted to be guided through the center, or axis of rotation, of the structure 33 to the feeding means 36 by means of rolls carried by spaced-apart roll stands 38 and 39. As best seen in FIGURE 3, rolls 4'1 43 provide a pass for the strip and are rotatably supported by the roll stand 38 in any suitable manner.

In order to prevent excessive twisting of the strip, the rolls 4t 49 are so positioned that the pass provided thereby holds the strip in a position which is normal to the position of the strip when it is aligned with the dies of the press 12 (compare FIGURES 2 and 3). In this manner, although the strip is turned from side to side about its longitudinal axis through an angle of 180 degrees by means to be disclosed, the strip will be twisted through an angle of only 90 degrees in either direction with re- 6 spect to the position in which it is supported by the rolls 40, 40.

Furthermore, since the present invention is adapted for use with strip which requires particularly gentle handling the amount that the strip is twisted, the width of the strip and the length of strip through which such twisting occurs preferably is so proportioned that the stresses set up in the strip by such twisting will be less than that which would impair the magnetic properties of the strip.

Roll stand 39 is similar to roll stand 38 in that it rotatably supports a pair of rolls which provide a pass for the strip. However, in the present embodiment, the axes of the rolls carried by roll stand 39 and the pass provided by the rolls are horizontal.

As shown in FIGURES 1, 4 and 5, roller supports 35 are secured to a slide 41 which is slidable in a guideway 42 supported by the floor or other supporting surface. For a purpose to be disclosed, means are provided for shifting the slide and its supported structure 33 longitudinally of the axis of the strip and such means presently comprises a fluid cylinder 43 (see FIGURE 1) secured to the slide 41 and having a piston rod 44 which is anchored to the floor or other supporting surface by means of a suitable bracket 45. Reciprocation of cylinder 43 rela tive to the piston contained therein will efiect reciprocation of the slide 41, structure 33 and the feeding mechanism 36 carried thereby.

Means are provided for effecting rotation of structure 33 about its axis and the coinciding longitudinal axis of the strip and such means comprise a sprocket 46 supported at one end of the structure by suitable supports 47. A chain 48 has an intermediate portion trained over sprocket 46 and end portions trained over respective sprockets 49 which are supported by respective brackets 50 secured to slide 41 (see FIGURE 5). Each end portion of chain 48 is also trained over respective sprockets 51 each of which is rotatably secured to a respective end of a piston rod 52 which extends from opposite ends of a fluid cylinder 53. Fluid cylinder 53 is secured to the slide 41 by any suitable means and each extreme end of chain 48 is anchored to a respective adjoining bracket 50 by any suitable means.

When piston rod 52 is shifted to the right as viewed in FIGURE 5, chain 43 will effect rotation of structure 33 in the direction of the arrow. Since sprocket: 46 is in the form of a ring, strip may be passed through the center thereof without interfering with rotation of the sprocket.

Operation of the present invention is as follows: Strip S will be fed between the rolls carried by roll stand 39, then between the rolls 40, 46 carried by roll stand 38, through the center of sprocket 46 and to the feeding means 35. The feeding means will then be actuated by any suitable means to feed a predetermined length of strip to the open dies 15, 16 of the press 12 and operation of the press will thereupon be initiated to sever the strip as heretofore described.

After the press has completed its cycle and a piece has been severed from the strip, the severed piece will fall from the dies as previously described and cylinder 43 will be actuated to shift structure 33 in a direction away from the press from the full line position shown in FIGURE 1 to the dot-dash line position. It is to be understood that such movement of structure 33 will withdraw the end of the strip from the die 15 for a purpose to become clear since the strip is tightly gripped by the rolls 37, 37 of the feeding means 36.

After cylinder 43 has shifted structure 33, any suitable means may be employed to effect operation of cylinder 53 to rotate structure 33 an amount sufficient to turn the strip side for side about its longitudinal axis. Since the strip has been withdrawn from the die 15, it may be freely turned. After the strip has been turned, cylinder 43 will return structure 33 to its full line position and feeding means 36 will operate to feed another predetermined length of strip to the press.

It is to be understood that the amount of material fed at each operation of the feeding means is suflicient to extend only a slight amount beyond the cutting knives 21a, 22a of die 16 to minimize scrap. By way of example, suflicient strip may be fed at each operation of the feeding means to extend approximately one-eighth of an inch beyond the knives of die 16. This is indicated in FIGURE 10.

It will now be clear that turning the strip side for side intermediate each cutting operation permits the cut made by die 16 to be positioned close to and parallel with the cut made by die 15 at the preceding press operation to thereby minimize scrap.

While it is preferable in the presently disclosed embodiment to employ two dies for cutting the strip material in order to insure cutting accuracy, it will be understood that under certain circumstances it may be desirable to employ only one die. In such event, turning the strip side for side intermediate each cutting operation will reverse the relationship of the cut end of the material and the cutting die and will permit generally keystone shaped pieces to be cut with a single die.

In view of the foregoing it will be apparent to those skilled in the art that I have accomplished at least the principal object of my invention and it will also be apparent to those skilled in the art that the embodiments herein described may be variously changed and modified, without departing from the spirit of the invention, and that the invention is capable of uses and has advantages not herein specifically described, hence it will be appreciated that the herein disclosed embodiments are illustrative only, and that my invention is not limited thereto.

1 claim:

Apparatus for cutting sheet-like material comprising a pair of spaced-apart cutters for cutting material in operable relation therewith, clamping means intermediate said cutters and having spaced portions engageable with respective opposed side edges of the material for clamping the latter position prior to cutting thereof with one of said material side edges disposed at a lower level than its opposite side edge, and means for moving that clamping means portion engaged with said one material side edge in a direction flatwise of the material and away from engagement with the latter following cutting thereof to provide for gravitation of the cut material away fro-m said cutters.

References Cited in the file of this patent UNITED STATES PATENTS 1,381,110 Dyblie June '14, 1921 1,982,880 Pachter Dec. 4, 1934 2,017,752 Fisher Oct. 15, 1935 2,165,614 Cook et a1 July 11, 1939 2,699,209 Norton Jan. 11, 1955 2,766,825 Pater et a1. Oct. 16, 1956 2,815,074 Dehn Dec. 3. 1957 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent N00 3,072,001 January 8, 1963 Richard F, Herr It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

column 2, line 61, for "material 8" read material S column 8, line 11, after "latter" insert in Signed and sealed this 6th day of August 1963.,

(SEAL) Attest:

ERNEST w. SWIDER DAVID LADU Attesting Officer Commissioner of Patents

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