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Publication numberUS2013976 A
Publication typeGrant
Publication dateSep 10, 1935
Filing dateSep 25, 1934
Priority dateSep 25, 1934
Publication numberUS 2013976 A, US 2013976A, US-A-2013976, US2013976 A, US2013976A
InventorsWales George F
Original AssigneeWales George F
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Adjustable perforating die
US 2013976 A
Abstract  available in
Images(1)
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Claims  available in
Description  (OCR text may contain errors)

Sept. 10, 1935. G. F. WALES ADJUSTABLE PERFORATING DIE Filed Sept. 25, 1954 Patented Sept. 10, 1935 UNITED STATES PATENT OFFICE 12 Claims.

My invention relates to adjustable perforating dies which are more particularly intended for use in press brakes, stamping, and similar presses although the same may also be employed advan tageously in other installations.

Heretofore adjustable perforating dies have been so constructed that the die elements have been rigidly mounted on the stationary bed of a press and the punch cooperating with the die mounted rigidly on the ram which moves vertically toward and from the bed. In order to adjust the punches and dies so that holes could be punched in difierent locations it has been necessary to loosen the die holder and clamp it to the bed of the press in its new location and then to loosen the punch holder and entering the punch into the die, to lower the press ram so that the punch holder could be clamped to the ram while the punch remained entered in its cooperating die. This has been a tedious and expensive operation.

The chief purpose of this invention is to provide an adjustable perforating apparatus which is so organized that no part of the punch or stripping mechanism is attached to the ram of the press but is self contained with the entire punching mechanism contained in one holder so that an adjustment of the holder locates the punch and die in its proper place in one setting.

A further objectis to provide a shoe on which the die holders are mounted and means for attaching the holders to said shoe so that a minimum of time and labor will be expended in adjusting the holders.

A further object is to provide a self contained punch and stripper which can be readily removed from the holder without disturbing any other part of the set-up. v

A further object is to provide a multiple hole die member which can be adjusted so that any one of a number of holes can be located under the punch center for the accommodation of its punch. This gives greater flexibility and economy of operation.

A further object is to provide a die member which can be readilyremoved from its position in the die holder and can be replaced with other die members having the same size or difierent size openings, without disturbing the setting of the holders on the shoe.

A further object is to provide a means for quickly adjusting each holder independently on "the shoe by mechanical means which may be locked so that the holder cannot move after being properly located.

A further object is to provide a shoe with calibrated means for locating the holders in proper relation to each other.

A further object is to provide a calibrated dial or pointer on each die holder to operate in conjunction with the calibrated scale on the shoe for 5 making accurate adjustments of the holders.

These and other objects and theseveral novel features of the invention are hereinafter more fully described and claimed and the preferred form of construction is shown in the accompanyl0 ing drawing in which:--

Figure 1 is a fragmentary'vertical section of a press brake showing an approved form of ad-. justable perforating die embodying my invention.

Figure 2 is a plan view of the removable die 15 member shown in Figure 1.

Figure 3 is a front elevation of the lower po u tion of the adjustable die holder showing the clamping arrangement for tightening the die holder to the shoe, and the scale for setting the holders.

Figure 4 shows an approved method of moving the holder in relation to the shoe by mechanical means together with a multiple hole die member.

Figure 5 is a front elevation of Figure 4 and 25 showing the calibrated scale on the shoe.

Figure 6 is a plan view of the die member shown in Figures 4 and 5.

Figure 7 is a fragmentary section of a template and nut lock. 30

In the following description the reference characters indicate like parts in the several figures L of the drawing.

Although this invention is capable of use in various installations the same is shown in the present case in the drawing as used in connection with a type of press commonly known as a press brake. It is obvious that the holders, shoes, and punching mechanism described in the drawing may be used with various types of machines, being varied in detail to suit conditions.

The numeral 10 represents the shoe whereby the punch and die holder H is supported upon the bed l2 of the press in which my invention is embodied and I3 represents the ram plate at- 45 tached to the vertically movable ram ll of the press. The numeral 15 represents the lower face of the shoe III which is attached firmly to the bed I! of the press in any conventional manner. The. height of the shoe is sufficient to allow room for 0 the loosening or tightening of the bolt l6 when the holder II is to be relocated on the shoe. The upper part of the shoe consists of a T-shaped head having a rabbet-shaped groove I! in its front upper part in which a guide l8 on the holder co- 55 operates to retain the holder in proper position so that the punch centers of all holders will be in proper relation to the vertical centerline and to each other, while at its rear upper part this T- shaped head has an angular face I 9 on which a cooperating face 20 on the holder causes guide II to automatically press firmly in its seat II.

This T-shaped head may or may not be equipped with a calibrated scale 2|, depending upon the requirements of the user. If the scale is used the holders may be set in properly spaced relation to each other by setting the same so that corresponding points on each holder, as for instance edge 52, are at desired distances from each other, thereby setting the punch centers the same distances apart, as the edge 52 is the same distance from the centerline of the punch on all holders preferably of the same size. The numeral represents the lower base and 22 the upper head which form the main parts of a holder whereby the operating parts of the perforating device of my invention are supported. This base and head are stationary while in use and are separated at their front opposing ends by an intervening gap 23 while their rear ends are held apart from each other by means consisting preferably of a foot 25 formed on the under side of the rear part of the head 22 and resting against the rear part of the upper side of the base H as shown in Figure 1. These two members of the holder are preferably detachably connected with each other and held against relative movement in a horizontal direction by means of screws 24 passing downwardly through the head 22 into the base II and also by means of dowels 26 engaging with corresponding openings in the rear parts of the base II and head 22 as shown in Figure 1.

In the front part of the upper side of the base II, the same is provided preferably with a rabbet having an upwardly facing seat 21 and an angular face 28 into which a longitudinal hole is bored to accommodate a dowel pin 29 which is driven or screwed into same so that an extension 30 of said pin projects forward into said rabbet. This dowel pin is preferably mounted in the holder although the pin may be mounted on the die member 3| which pin would then be inserted into the hole bored in the holder. In either case the dowel is preferably on the longitudinal centerline of the holder I l, as shown in Figure 2. As shown in Figures 1 and 2, a die member 3| which fits into said rabbet is provided with a hole bored to accommodate the extension 30 of dowel pin 28. On the longitudinal centerline this die member is provided with a die opening 32 extending vertically through said die member, the vertical centerline of this die opening being the vertical axis of its cooperating punch which will be referred to later. The front portion of the die member 3| is provided with another hole 33 which may be of various forms but is shown in Figure 1 to be tapered to accommodate a taperheaded screw 39 which when tightened into the holder by means of the screw thread 34 serves to clamp the die member firmly to the holder and also to locate said die member so that the die opening 32 will always line up directly on the axis of the punch. This taper-headed screw is located on the longitudinal centerline of the die member and holder in such manner that it may be inserted or removed without being interfered with by the upper head 22.

Lower base II is provided with a discharge chute 35 which opens at its upper end in seat 21 on the same center with die opening 32 and communicating therewith, while the lower end of the chute 35 extends at an angle toward the rear of the base and terminates at the under surface of same at a point far enough back to clear the taper face l9 of shoe l6, thereby allowing the punched-out slugs to fall freely onto the bed I 2 of the press or to otherwise be disposed of.

By extending die member 3| above the base of the holder the die may be sharpened at the top when the same becomes dull.

The front under part of lower base II is provided with a groove 36 in which a clamp 31 is guided. Clamp 31 is provided at its lower rear part with a backwardly extending flange 38 which engages with the under side of the T-shaped head of shoe l0 so that when clamping screw I6 is tightened it causes a locking which prevents the lower base I from moving from its position in relation to shoe I0. In order to assure this locking action there is a slight clearance between the clamp and lower base as shown at 40 and 4| in Figure 3.

The front part of the head 22 of the holder is provided with a vertical guideway 42 of circular form which is axially in line with the die opening 32 of the die member 3|. Within this guide opening 42 is arranged a punching unit which is so organized that the same is capable of sliding vertically in this opening toward and from the die member 3| and adapting the same to the upper surface of the sheet of material which is being punched, and also to permit of driving the punching element downwardly through the sheet metal and into the die, and also to enable this punching device to be removed as a unit from the head of the holder and replaced by one having a different size of punch. The particular organization of this punching device, as shown in Figure 1, is constructed as follows.

The numeral 43 represents the lower or working end of a punch, having a cylindrical body 44 smaller in size than said working end, thus forming an upwardly facing shoulder 45. On its upper end this punch is again reduced in size to 45 form a second upwardly facing shoulder 46 and this upper end then provides a seat 41, on which an upper abutment disk 48 is mounted and also provides threads 5| on which lock nuts 49 and 50 are tightened to hold said upper abutment 50 disk 48 securely against said shoulder 46, while surrounding the lower end 43 of the punch is a bearing disk 53 having a downwardly facing shoulder 54 engaging the upwardly facing shoulder 46 of said punch. The under side of this 55 bearing disk 53 extendsslightly beyond the lower surface of the punch and is rounded or beveled as shown by numeral 55. Surrounding the body 44 of the punch is a helical spring 56 which bears at its lower end against the upper side of the 60 bearing disk 53 while its upper end bears against the underside of the abutment disk 48. This spring between the bearing and abutment disks tends to keep the disks separated and also serves to withdraw or strip the punch from the work piece 51 after a hole has been punched into the same, as will presently appear. The movement of the bearing disk and abutment disk away from each other is limited by engagement of the shoulders 46 and 54 of the punch and bearing disk.

This punching unit is capable of floating readily within the guide opening 42 in the upper head 22 of the holder and when the press is not in operation the-lower rounded end ll of the bearing disk I! rests on the upper side of the die 3|.

Upon pushing or feeding a sheet ll of the metal or other sheet material constituting the work 5 piece into the gap 23 of the punch and die holder preparatory to being perforated, the engagement of this sheet with the rounded lower end ll of the bearing disk operates to lift the latter together with the other elements of the punching unit due to the stiffness of the spring it. After the work-piece I1 has been properly placed between the die and punch of the perforating mechanism the ram H of the press descends with a working stroke and by engaging with the upper end of the nut ll causes the punch to be pushed downwardly so that its lower end punches a hole through that part of the sheet immediately below the lower bearing disk 53 and forces the same through the opening 32 in the die member, from which latter, the punched out slug is delivered by the chute to the exterior of the die and punch holder,

When assembling the various elements associated with the punching unit the spring 58 is placed under an initial compression so as to enable the same together with the added compression which is imparted thereto during the punching operation to effectively withdraw the punch from the opening which the same has formed in the sheet material and thereby strip the latter from the punch.

During the punching operation the punch and abutment disk descend independently of the bearing disk 53 and at this time the spring 58 is compressed to a greater extent than that which was initially imparted to the same when assembling the several parts of the punching device preparatory to using the same in the press.

As the ram it rises and is withdrawn from the upper side of the nut 50 the resilience of the spring 56 operates to strip the punch from the opening in the work piece 51 thereby leaving the latter free to be withdrawn from the gap 23 of the holder and the die and punch which are mounted in same.

For the purpose of punching holes of a different size in sheet metal or other material the die member 3| and the punch and bearing disk 53 may be replaced by other corresponding members adapted for punching holes of either larger or smaller sizes. This change is readily efiected by withdrawing the punching unit from the head of the holder and unscrewing the nuts 49 and 50 so that a new punch and bearing disk to fit it may be assembled with the spring, abutment disk, and lock nuts previously used. Or an entire new punch and stripping guide assemblage with a different size punch may be inserted in the holder. To'change the die member 3|, screw 3! is removed, thus permitting the die member to be withdrawn from its position on dowel pin extension 30. In placing a die member in the holder it is first necessary to enter the dowel pin extension into the cooperating hole in the die memmember and then by tapping lightly on the outer end of said die member, to force it home so that its back face is snug against its angular seat 28. The taper screw 39 is then put in place and screwed down tightly so that the tapered head seats both in the die member and lower base as shown at 39 and 58 in Figure 3, thereby causing the die member to line up with the die opening 32 directly under its cooperating punch end 43.

If now it is desired to punch a number of holes in one work piece 51, at say six inches apart, the

first punch and die holder is set with edge '2 at any position on the shoe. In the drawing edge I! is shown set at 4 inches on the scale 2|. The second holder is then set at inches, the

third at 16H inches etcetera, and this arrange- 5 ment would produce the required work pieces, with holes six inches apart, after the punching .operation had been performed as explained previously. In many instances work pieces are required with the holes at more exact center distances than can be obtained by the scale settings. when this accuracy is desired any of the conventional measuring instruments or methods may be used to correct the settings made by use of the scale, or an accurately made spacing templet preferably as shown at 66 in Figures 4 and 5, and described later, may be used.

Figures 4, 5 and 6 show another variation in the construction of the punching device which comes within the scope of this invention and also a variation of the means for moving the punch and die holder laterally on the shoe for quick and accurate adjustments.

The die holder and shoe shown in Figures 4,

5 and 6 is substantially like that shown in Figures l, 2 and 3 but differs therefrom as follows.

In Figure 4, the shoe III, has firmly attached to the front under side of its T-shaped head a gear rack 59, preferably by means of screws 60, said rack extending substantially the entire length of said shoe. Lower base I l of the punch and die holder is substantially like that shown in Figure l but differs therefrom in that an apron 6| extends downward in front of the T-shaped head of theshoe, so as to provide a bearing 62 for the gear shaft 63 of a preferred means for mechanically moving said holders laterally on the shoe and which is constructed as follows.

In order that the teeth on gear rack 59 and pinion 64 engage witheach other in a manner prohibiting any play or lost motion between them, the bearing hole 62 is bored in the apron 6| at an exact distance below said rack. Into this bearing hole 62 a shaft 63 slightly smaller in diameter than said hole, and having a geared 5 pinion 64 as an integral part thereof, is inserted so that the teeth on the gear pinion engage with the rack teeth. Shaft 63 is slightly shorter than the thickness of apron 6| in order to allow the tightening of nut 68 on the threaded extension 69 of said shaft to cause a binding action between the inner surface I0 of said gear pinion, washer 61, and said apron. This gear shaft is further provided with an extension II to accommodate a wrench for turning same. Thus when nut 68 is loosened on shaft 69 it relieves the clamping pressure on the apron and a wrench applied to extension 1| turns the pinion and causes the entire holder II to move longitudinally in relation to rack 59. The holders are thus set in relation to each other, being spaced properly by means of scale 2 l As each holder is placed in position the nut 68 is tightened on screw 69 thus causing the binding action between the face III of the pinion and washer 61, on both sides of the apron 6!, which locks the holders in position.

In some instances a certain setting of the holders is repeatedly required and in order to save time in such cases each holder is provided with a pin 66 which projects sufliciently out of 70 the holder to accommodate a strip template having holes bored slightly larger than the pin diameters and at the proper center distances. As the holders are moved until the pins enter the holes in the template and are then looked in position as described above the setting may be done rapidly. The template may then be removed or allowed to remain in position, in which case the pins 12 are threaded into the holder and also to accommodate a nut 13 which when screwed on the outer end of the pin or stud holds the template in position as shown in Figure 7.

In Figures 4, and 6 is shown an alternate die member 14 having a number of diiferent size holes. This die member is held in position by being dove-tailed into the holder as shown at 15 Figure 5 and also by means of screws 16. Thus the die member may slide in its dove-tailed seat in the holder until any one of the die openings is located under the centerline of the punch, which being changed to match the hole in the die enables a hole of that size to be punched. When another size hole is required the die member is reset to the size required and the punching unit in the upper arm changed to match.

In assembling the holder assemblage on the shoe III as shown in Figure l a loosening of clamp bolt l5 enables the holder to be hooked onto the T-shaped head of the shoe, whereas the holder as shown in Figures 4 and 5 have to be started from the end of the shoe because of the gear pinion and rack.

In the above specification I have described one form of my invention, but it will be understood that the same is capable of further modification without departing from the spirit and scope of the invention as defined by the following claims.

I claim as my invention:

1. In a machine having a stationary bed and reciprocating ram, an adjustable perforating apparatus comprising a rail mounted on said bed, a holder having a lower base and upper head slidably mounted on said rail, means for adjustably locking said holder on said rail, 9. perforating die mounted on said base and a punching device mounted and guided on said head as a punching unit including a punch cooperating with said die upon pressure being applied on said punch by said ram, and a spring stripping means for withdrawing the punch from the material worked upon.

2. In a machine having a stationary bed and reciprocating ram, an adjustable perforating apparatus comprising a rail mounted on said bed, a holder having a lower base and upper head slidably mounted on said rail, means for adjustably locking said holder on said rail, a perforating die mounted on said base and a punching device mounted and guided on said head as a punching unit, which unit is capable of floating freely on said head and is also capable of being freely assembled with said head and removed therefrom and including a punch cooperating with said die upon pressure being applied on said punch by said ram, and a spring stripping means for withdrawing the punch from the material worked upon.

3. In a machine having a stationary bed and reciprocating ram, an adjustable perforating apparatus comprising a rail mounted on said bed, a holder having a lower base and upper head, slidably mounted on said rail, means for adjustably locking said holder on said rail, a perforating die mounted on said base and a punching device mounted and guided on said head as a punching unit, which unit is capable of being freely assembled with said head and removed therefrom and is also capable of floating freely on said head and includes a lower bearing disk, a punch projecting upwardly through said bearing disk and having an upwardly facing shoulder engaging with a downwardly facing shoulder in said bearing disk, which disk surrounds said punch and extends flush with or slightly below its cutting 5 face and includes an inclined lower face adapted to be engaged by the work upon pushing the latter between said bearing disk and die member and thus automatically raising said unit, an upper abutment disk engaging with an upwardly facing shoulder on the upper end of said punch, said abutment disk being held concentric with said punch by fitting around a seat on the latter and being held firmly against said shoulder by means of lock nuts threaded on the uppermost end of said punch, and a spring surrounding said punch and hearing at its opposite ends against said bearing and abutment disks thus exerting a strong initial pressure on said bearing disk for stripping the punch from the material worked upon.

4. In a machine having a stationary bed and reciprocating ram, an adjustable perforating apparatus comprising a rail mounted on said bed,

a holder having a lower base and upper head slidably mounted on said rail, said lower base being provided on its front upper face with a seat, a die member removably mounted in said seat, and means for centering the die opening in said die member on the vertical axis of the punching unit which floats in a guideway bored in said upper head, said lower base being provided with a chute extending from beneath the die opening in said member to the rear lower side of said base thus causing the punched out slugs to be disposed of in the rear of said machine.

5. In a machine having a stationary bed and reciprocating ram, an adjustable perforating apparatus comprising a rail mounted on said bed, a holder having a lower base and upper head slidably mounted on said rail, means for adjustably locking said holder on said rail, said lower base being provided on its front upper face with a seat, a die member removably mounted in said seat, and means for centering the die opening in said die member on the vertical axis of the punching unit, including a dowel pin projecting from said seat, an aperture in said die member engaging said dowel pin, and a locating and clamping bolt projecting through a companion opening in the die member and into said base, said base projecting beyond the front face of said upper head to provide clearance in the assembling and removing of said bolt, and a punching unit including a punch cooperating with said die opening and spring stripping means for withdrawing the punch from the material being worked upon.

6. In a machine having a stationary bed and reciprocating ram, an adjustable perforating apparatus comprising a rail mounted on said bed, a holder having a lower base and upper head, slidably mounted on said rail, means for adjustably locking said holder on said rail, a perforating die mounted on said base and a punching device mounted and guided on said head as a punching unit including a punch cooperating with said die upon pressure being applied on said punch by 6 said ram, and a spring stripping means for withdrawing the punch from the material worked upon and means for locating said perforating dies at desired distances including marked measure- 70 ments on said rail to which said holders are set.

7. In a machine having a stationary bed and reciprocating ram, an adjustable perforating apparatus comprising a rail mounted on said bed,

a holder, having a lower base and upper head, 75

slidably mounted on said rail and means for adjustably moving said holder longitudinally on said rail, including a geared rack attached to said rail, a pinion engaging said rack and provided with a shaft extending through a bearing in said lower base and means for revolving said shaft and pinion including a wrench seat at the endof the shaft opposite said pinion, and provision for locking said holder after said adjustment, by preventing said shaft from turning, including an external thread on the portion of the shaft between the wrench seat and outer face of said bearing and a nut on said thread for tightening against said face, said lower base being provided with a perforating die, a punching device mounted and guided on said head as a punching unit, including a punch cooperating with said die upon pressure being applied on said punch by said ram, and a spring stripping means for withdrawing the punch from the material worked upon.

8. In a machine having a stationary bed and reciprocating ram, an adjustable perforating apparatus comprising a rail mounted on said bed,

a holder, having a lower base and upper head,

slidably mounted on said rail and means for adjustably moving said holder longitudinally on said rail, including a geared rack attached to said rail, a pinion engaging said rack and provided with a shaft extending through a bearing in said lower base and means for revolving said shaft and pinion including a wrench seat at the end of the shaft opposite the pinion, and provision for locking said holder after said adjustment, by preventing said shaft from turning, including an external thread on the portion of the shaft between the wrench seat and outer face of said bearing and a nut on said thread for tightening against said face, said lower base being provided with a perforating die, a punching device mounted and guided on said head as a punching unit, including a punch cooperating with said die upon pressure being applied on said punch by said ram, and a spring stripping means for withdrawing the punch from the material worked upon, and means for repeatedly locating a number of said perforating dies in the same relation to each other including a dowel pin projecting from said holders and an independent templet providedwith holes at the desired intervals in which said dowels enter, upon said holders being moved longitudinally to engage same.

9. In a machine having a stationary bed and reciprocating ram, an adjustable perforating apparatus comprising a rail mounted on said bed, a holder, having a lower base and upper head, slidably mounted on said rail and means for adjustably moving said holder longitudinally on said rail, including a geared rack attached to said rail,.

a pinion engaging said rack and provided with a shaft extending through a bearing in said lower base and means for revolving said shaft and pinion including a wrench seat at the end of the shaft opposite said pinion, and provision for locking said holder after said adjustment, by preventing said shaft from turning, including an external thread on the portion of the shaft between the wrench seat and outer face of said bearingand a nut on said thread for tightening against said face, said lower base being providedwith a perforating die, a punching device mounted and guided on said head as a punching unit, including a punch cooperating with said die upon pressure being applied on said punch by said ram, and a spring stripping means for withdrawing the punch from the material worked upon and means for repeatedly locating a number of said perforating dies in the same relation to each other including a dowel pin projecting from said holder and a templet provided with holes at the desired intervals in which said dowel pins enter upon said holders being moved longitudinally to engage same, and provision for holding said templet as an attachment to said holders including a thread on the projecting end of said dowel and a nut on said thread for holding said templet against said holder.

10. In a machine having a stationary bed. and reciprocating ram, an adjustable perforating apparatus comprising a rail mounted on. said bed, a holder, having a lower base and upper head, slidably mounted on said rail and means for adjustably moving said holder longitudinally on said rail, including a geared rack attached to said rail, a pinion engaging said rack and provided with a shaft extending through a bearing in said lower base and means for revolving said shaft and pinion including a wrench seat at the end of the shaft opposite said pinion, and provision for locking said holder after said adjustment, by preventing said shaft from turning, including an external thread on the portion of the shaft between the wrench seat and outer face of said bearing and a nut on said thread for tightening against said face, said lower base being provided with a perforating die, a punching device mounted and guided on said head as a punching unit, including a punch cooperating with said die upon pressure being applied on said punch by said ram, and a spring stripping means for withdrawing the punch from the material worked upon, and means for locating said perforating dies at desired distances including a measuring scale on said rail to which said holders are set.

11. In a machine having a stationary bed and reciprocating ram, an adjustable perforating apparatus comprising a rail mounted on said bed,

a holder, having a lower base and upper head,

slidably mounted on said rail, means for adjustably locking said holder on said rail, an adjustable multiple hole perforating die member mounted on said base and a punching device mounted and guided on said head as a punching unit including a punch cooperating with said die upon pressure being applied on said punch by said ram, and a spring stripping means for withdrawing the punch from the material worked upon.

12. In a machine having a stationary bed and reciprocating ram, an adjustable perforating apparatus comprising a rail mounted on said bed, a holder, having a lower base and upper head, slidably mounted on said rail, means for adjustably locking said holder on said rail, an adjustable multiple hole perforating die member mounted on said base and provision for tightening same in said base, including a dovetail shaped seat in said base, a dovetail shape on said die member cooperating with said seat, and locking screws in said base which upon being tightened press against said die member locking same in said seat, and a punching device mounted and guided on said head as a punching unit including a punch cooperating with said die upon pressure being applied on said punch by said ram, and a spring stripping means for withdrawing the punch from the material worked upon.

GEORGE F. WALES.

Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US2553615 *Mar 19, 1943May 22, 1951Wales George FMethod and apparatus for perforating sheet material
US3077134 *Dec 4, 1958Feb 12, 1963Baldwin Lima Hamilton CorpShear for cutting billets, beams, and the like
US3114280 *Dec 14, 1960Dec 17, 1963Houdaille Industries IncPunching device
US4440052 *Sep 12, 1980Apr 3, 1984Unipunch Products, Inc.Punch assembly with unitary stripper spring assembly
Classifications
U.S. Classification83/143, 83/616, 83/560, 83/165, 83/549
International ClassificationB21D28/26, B21D28/24
Cooperative ClassificationB21D28/265
European ClassificationB21D28/26B