US1788023A - Punching device - Google Patents

Description

Jan. 6, 1931. H. HOCHREINER 1,738,023

' PUNGHING DEVICE Filed Jul 3.9, 1927 ATTORNEYJ 4 sive to make, and this is especially thee ltlateirized Jan 6, 1931 UNWEEE fsrerss rATENro F cE- I ans nocnaninnnbr Emi ma, NE JE SEY, ASSIGNQR TO cTno Dynam c .ooMraNY, orsaronnn, ivnwar esnr, A oonronarron or NEW mass solver-nus DEVIC Application filed. 5111 19,

This invention relates to punches for making apertures or openings in materials'such as sheet metal, and has particular reference to punches ofa complex shape such as those each of which are adapted to register with corresponding apertures or openings in the next adjacent laininations so as to form slots or grooves for the reception of the dynamo windings; g Y

Fornierlmall of theseapertures or openings awere punched in'the rotor and stator blanks simultaneously or in relatively large groups, thus necessitating the use of large punchblocks or plates having the individual itun'ches formed" thereon. This form "of punch was obviously very expensive and laborious to make, and any defects which developed therein, such asthose caused by the breakage or Warping of certain" portions during heat treatment or use, made itauseless, so that theentire punch block or plate had to be replaced at great expense. Art the 1 present t-nne, especially 'i'nltorn'nng the lam} inations for the larger-sized rotors and stators, one or more individual punches and. the

corresponding dies are indexedaround the sheet metal blank or the blank is indexed around the stationary punch and die; or

punches and diesi ,3 c

In thisway fewer puncnes ,and lessmanufacturing expense no the individual punches are still very ex where the punches include relativelyrlth'in curved blades such as are provided for the purpose of. separating the rotor blank from the stator blank simultaneously rth the forg- Q mation of the winding slot apertures, this "ternal' strains which are set up in the metal,

- not; This has not been possible to any extent heretofore employed. Among the other ob- 1e27. Serial my 206,814.

separation also formingthe' clearance b etween the, finished rotor and stator when they are operated in the dynarno-electric machine. lnorder to obtain this proper clearance the cutting-0E blade pcrtionof the punch must necessarily bethinr frequently not exceedingtwenty thousandths of aninchflinthickness. This thin blade portion of the punch. is not only very susceptible to breakage and distortion in handling and use due to the thinnessand brittleness of the hardened metal; but frequentlybe comesWarped and cracked during the heattreating process because of the unequal in- W O and consequently theentire puncl 'must be scrapped since it is useless for the purpose intended; I e Furthermore, inasmuch as a great number of winding slot openings or apertures are required ineach rotor and stator lamination, and as great n'umber of laminations are'necessary to makeup the completed rotor and-stator units each punch should be capable of producing a sufficient number of punching operations Without undergoing any appreciable impairment, in order to equalize tliecost; of making the punch as compared to the value of the finished prodheretofore unless especially fine steels were used, and mostacc urate tool Work and eljab0- rate-heat? treatment were resorted to, but these elaborate precautions, although in- ,creasing'the life of the punch somewhat, also increased thcfcostthereof so that these precautions Were no "inore'warranted than the more frequent 1 change of punches made in the usual-manner;

' It is the principal ob ect of this invention 3' -to,;obviate theseyobjectigons byfprovidinga p-punclnn'g apparatus .--Wl1 ich1s more rugged, has-fa longer hffe,"1s less expensive, and wl'neh is more efficientthan thepunching apparatus jects of-the inventionis to provid'ea punch which isybuilt upin e'oacting sections, each section being a separate element' which contributesto the composite Whole punching'lunit. 7 Accordingly, 3 each section'being interchange able, may be replaced when worn or broken, and is heat-treated separately,.so that whatevcr breakage occurs, due tointernal strains set up in the metal during heat treatment,

does not affect the remainder of the punch.-

In this way the cost of making and-replacing I punches is reduced to a minimum and variations indimensions of the product cut by the punch is avoided, as well assecuring the'de sira b'le' interchangeability of punch parts in a simple manner; 7

In addition to the solution of the problem.

of readily handling the thin blade-like parts of a punch in the manner described, the punch of this invention may be so' formed that these thin'blade-like' portions may be formed in the punch hlockto various'shapes, such as curved or angular, without the necessity of cutting these shapes out of a solid block of steel; This facilitates and decreases the costof making and assembling, as well as procuring a'ver'y efiicient and durable tool;

Furthermore, the division of the punching unitinto several sections maybe effected in the most economical way, taking into consideration facility with which the different sections may be made. This is also of especial value from the standpoint of heat treatment,

since the more regular in shape that the dif ferent sections are, the better'the heat-treat:

ment,'i.- 'e.',,the heat penetration is more uniform and the internal strains are less, thus resultlng n less distortion of the finished punch. I V 1 g V p 7 Another objectwof the lnvention is to pro 'vide a punch which has a longer life than those heretofore employed, which is especially valuable where the nature ofthe work re quires that each punch be capable of a great numherof punching operations in order to justify'its original cost as compared to they valueof the finished product. As pointed out above, this 1S especlally desirable in punching lamination, blanks for rotors and stators of dynamoclectric machines wherea great number of the same punchingoperations are required to form a singlerotor orstat'or unit.

. This object isaccomplishedin the present invention by shaping-the working surface of the punch 111 such away that the scrap metal which. is punchedout of the blank does not drag upon the. cutting'edges of the punch,

but is bent out of the way to afford clearance. Tests have proven in a number of typi ml instances, th at the life of a punch thusformcd is increased from 20,000to140g000: punching operations, which procuresafgre'at saving without exercising extraordinaryicarefin making, employing relaborate'lhe'at treatment, orusingspecial'toolsteeL \Vhile thedescription an'd'operation of the punch of this invention: isipresented" in' 'connection with the forining of dynamo-electric .machine'lamination blocks-fon rotors and stators, it is to :be "understood: that the'punch very expensive.

is not limitedto that particular use but applies equally well to use in punching various 7 shapes for different purposes from blanks of sheet or heavier material.

For a better understanding of the inventionreference is made to the accompanying drawings in which 7 Figure 1 is'a. diagram indicatingthe arrangement of the perforations commonly made in rotor and stator lamination blanks and illustrating the manner in which the ro- V tor and stator blanks are separated simultaneously with the punching operation; .7 Fig. 2 is a face View of a composite punch embodying the invention;

Fig. 3 is a vertical section of the same'which also shows its operation in connectionwith the sheet metal blank and the cooperating die; I V V V Fig. 4 is, an end elevation of'the punching unit illustrated in Fig. 2; and

Fig. 5 is an enlarged perspective cross section of one of the punching elements taken along line 55 of Fig. 2. 1

In these drawings,the numeral 10 designates the blank of sheetmetal from which the rotor and stator lamination's are stamped or punched. In forming these laminations, the J tions. The winding slots 15 in the stator lam:

inations are punched in a similar manner.

In performing punching operations of the type described, it is evident thatin order to obtain laminations of the proper shape with the proper clearance between the rotor and stator units when they are assembled into the finished product, punching element 13 must be curved according to the are of the clearance between the rotor and stator and also must be of suliicient thinness to maintain the proper clearness between the rotor and stator. In punches made for this purpose heretofore, it has been the practice to shape the entire punching unit out of one piece, thus necessitating a great deal of machine work which. is

ing unit was properly shaped, the thin blade like portion subjected to breakage or rli'" tort-ion due to usage, unequal strains of heat treatment and the'hke. Consequently when breakage occurred, the whole punching unit hadto be scrapped which obviously entailed z t considerable lossJ I V Y In the present invention these objections are obviated'bymal-ring thefpunching unit out of a number of punching elements wlnchiwhen lac However, after the punchof-such shape that they may be properly assembled co-act to form a punching unit.v In this way, punching elements which i are broken or worn may be.. replaced and are readily made from standard stock. i 1 Referring to Fig. 2, the piu1ching element 11 is inserted in a'slo t"provided-in base-16 upon which isniounted a U-shaped block 17-. by means of screws 18., Thus. U shaped' block 17 embraces the sides of puncl'iing element 11 and holds it in place by means of screw orpin 19.. The stripper plate 20- is slidable on punching element 11 and'ismounted on 'the base 16 by means of pins'or studs 21j=sur- .mg element 11 springs 22..

Accordingly, a minimum amount of mach-inroundedby springs 22 in the usual manner.

.VVhen not in-use clips 23 hold the stripper plate 20 in position butthese clips 23 are re- .moved when the punchingunit is inuse so thatstripperplate 20 may slide upon punchagainst the tension of Block 17 is provided with a recess for the reception of plug 24 which is held in'place by meansof screws 25. The surface of plug 24-,which engages the vertical portion of block 17 is curved to the same extent thatthe clear ance space between the rotor and stator laminations iscurved. A slot having a similar curvature is provided in stripper plate 20 folthe reception of punching element 13.

Punching element l3, however, is initially a. stra ght and flat piece of steel but when it is clampedbetwe'en the curved surfaces of plug '24 and block 17, it is forced into'a curved.

shape such as illustrated in the drawings. In this way punching element 13n ay be. shaped as desiredwithout being machine shaped and at the same time forms a rigid punching element which co acts with punching element 1-1to make ajcomposite punch;

ing is required and both punching elements 11 and 13 may be removed and replaced merely by removing screws 19 and 25, respectively.

I 20,000 to:140,000 punching operations. This increasedoperating time isprocured by re cessing or grooving the operating face of the punch in the mannerillustrated by Fig; 5; Fig. 5 is an exaggerated cross section. oi punclnngelement 11 taken along theline 5+5 of Fig. 2 and shows the longitudinal recess or groove 26 which is ground therein.

heavier and thicker blades.

'The edgesof tl1is recess are'spaced as indicated at. 27 from the edges of the punching element. "This spacing of the edges of the groove from the edges of the punching element is important inasmuch as the recess 26 is not intended to cooperate with the cutting .eclges,'oftlie punch in the way of increasing the cutting..-angle or sharpening the cutting edges but isadaptedto impart a curve or bend to the-piece of scrap when it is cut from the blank ,lOflThis bending of the scrap causes the edges thereof to be drawn away from the cutting edges of the punch, the edges of: the aperture formed in the blank 10 and the'sides of the die 28 shown in Fig. 3/ In this way,-,th e usual drag of the scrap is eliminated and since this drag has .a harmful effect upon the cutting edges of the punch andithe die, their effectiveness is prolonged to a considerable degree. While punches such as rivet hole punches have been formed withrecesses heretofore, these recesses extend to the cutting edges of the punch and wereformcd for the primary purpose of increasing the. cutting angle of the cutting'edge and sharpening the Lil cutting edge; This expedient, while increasing the cutting efficiency and cutting rapidity the life thereof. Thisiwas due to the fact that sharper'edges andthinner blades of the same kind of materialhave a shorter life than The new man- 'of the-punch decreased instead of increased ner of forming punches,as illustrated particularly in Fig.5 of the drawings, is accordingly of considerable advantage in the way of increasing the efliciency and the length of life of the punch thus formed. r

In'Fig. 3 i illustrated he customary man ner* of operating the punch in which the blank "10 is inserted between the punching :ez P apparatus mounted on base- 16 and the die "28: mounted 1n plate 29; The punch is re- 8 'ciprocated so that the mnching unit comprising punch ng elements 11 and '13 perforatesblank 10 as indicated at 12 1n Fig.

through blank 10, stripper plate 20 engages ,blanklO and is retracted against the pres- ;sur'eo'f spr ngs 22. Accordingly, when the punch is withdrawn, stripper plate 20 tends T to return to its original position and thus forces the blank 10 fromthe punching ele ments 11 and'13. As illustrated in Fig. 1,,

when either the punching apparatus orthe "blanklO are'indexed a-rounch punchingele- (luf /S ment. in its successive pcsitions opei to form clearance groove or space 14. and

"at the same'time to separate the rotor and stator 'laminations from blank 10. Apertures 15 in the stator may be made in asimi- After: thepunching unit has penetrated.

lar manner either simultaneously with or .7

subsequently to the punching of. apertures 12 andgroove 142.1,, Y

The new pun ching apparatus accordingly 1 procures increased 'efliciency at decreasedexpense especially in puncl involve a great numbenot' l tions such as the formatien .oif l'aminations "for rotors and stature, of dynamo-electric distortion". 01

3 elements posit-ion;

1 a ElliS which 4 operamachines. T] e accuracy and interchangeability of the separate punching elements which make up the composite punchingunit permit replacement; of gparts, broken, or vdamaged and avoid losses Which etherwise 'ec'cui through V the necessity of duplicating parts Which'are not Worn because other; parts have been injured in use. By dividing the Whole punching unit into-numerous punchlements which are so tormeelas to make th 11' originalmachining V sible, very complicated punching shapes may be formed Without requiring the expensive and difficult machining" operations usually attending the manufacture ofsuch punches. Furthermore, by providingmeens whereby the thin portions of punching units may be separately made and shaped into the rcquii-edpunchin shape, a further saving in nnichining procured, aswvell as the elimination of the losses caused by cracking and these thin parts during the heat treatingprocess.: All of these various features contribute to the increased efficiency and life ofthe punch of this invention.

lclaimz V In a punching device, the combination id punchingelement, a frame having tor receiving the element, a flexible element adapted to form-a come e L y c'iing unit With the first element second slot in the frame termed to a preetermine-d shape for bendingthe flexible element to the predetermined shape,-'and ind epenclent means for removably holding the 2. In apunchingdevice; the combinetion at a rigid punching element, a flGXlblG punch ing'elemcnt adapted to be bent against-a portion of the rigid element and cooperate as simple as poshaving a cutting face formed \vithwa sl'lalloiv depression speced from the cutting edges thereof, a fiexiblepunching element adapted to be bent into cooperating relationshipwvith the rigid element to form a compositepunching unit, and a. frame for holding the flexible 7 holding'the elements in said shape to form a composite'punching unit; and means form- 111g part of the frame for permitting 111(k) pendent removal and replacement of 'each element. In testimonywhereof I afiix my signature.

A HANS HOCHREINER,

therewith to term a compositepunching unit,

a frame having for bending the flexible clement into the predeterminec shape and tor-holding the elen'lents in rigid cooperating relationship and means forming pert-of tine irame'for permitting the removal. and

Eng element vadapt-ed to be bent over alporv tien of the ri 1 element and cooperate to form a comnosite mnchine' unit at :t'ramc l e =9 V 1 having slots snaped to receive the elements in'tl. 7' final arrangement, means ceoperat-' mg'wiih the ir'ame for holding the flexible element n bent relation to the firstielement,

and securing means passing'through each element. l n v 4;. In a punching device, the combination ;;of ai'igid punching element, ,saidn e'mnient

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