Title:
PERFORATING DEVICE
United States Patent 3715947


Abstract:
A perforating device of improved construction is disclosed comprising a C-shaped holder having an upper arm carrying the usual punching and stripping assembly and a lower arm which is provided with a horizontal slot to leave a portion of this lower arm above the slot to embrace the usual die button about its full circumference, an apertured plate-like member composed of a harder material than the holder being removably arranged in said slot to provide an upwardly facing annular seat for the die button, this member backing up the die button and being in turn supported over a larger area on the lower portion of said lower arm which thereby acts as a base for said member.



Inventors:
Weisbeck, Ralph L. (Buffalo, NY)
Daniels, Dennis (Williamsville, NY)
Application Number:
05/101583
Publication Date:
02/13/1973
Filing Date:
12/28/1970
Assignee:
UNIPUNCH PROD INC,US
Primary Class:
Other Classes:
83/685, 83/698.91
International Classes:
B21D28/24; B21D28/34; (IPC1-7): B26F1/14
Field of Search:
83/685-691,698,700,140
View Patent Images:
US Patent References:
3079824Punching device having a spring biased stripperMarch 1963Schott
2364401Interchangeable punch and die and retainer for sameDecember 1944Stellin
1621811Punch and die retainerMarch 1927Richard et al.
1279362N/ASeptember 1918Krueger



Primary Examiner:
Meister, James M.
Claims:
What is claimed is

1. In a perforating device including a holder having an upper stationary arm spaced above a lower stationary arm to provide a clearance therebetween, said upper arm having a bore for a punching and stripping assembly movable toward and from said clearance, said lower arm having front end and side faces, the improvement which comprises means providing a slot in said lower arm spaced below said clearance and extending fully across said lower arm between its said side faces and opening to its said front face to leave an upper portion of said lower arm above said slot and an integral lower portion of said lower arm below said slot, said upper portion having a circumferentially continuously enclosed die receiving opening extending between said clearance and slot, said lower portion having a slug-ejection opening extending from said slot, an apertured die back-up member insertably and removably arranged in said slot and having an upwardly facing annular die-supporting surface, said member being composed of a harder material then said lower arm, and die-disassociated means removably securing said member to said lower arm.

2. A perforating device according to claim 1 wherein the aperture of said member has a first counterbore, said opening in said lower portion has a second counterbore, and such securing means includes a split ring element arranged in said counterbores.

3. A perforating device according to claim 1 which further comprises means arranged in said upper portion for removably locking a die in said die-receiving opening.

4. A perforating device according to claim 1 wherein said member is a plate having an upper plate surface and a lower plate surface, said lower portion having an upper plate-supporting surface engaged by said lower plate surface over substantially the full area of the latter, and a part of said upper plate surface providing said die-supporting surface and being of smaller area than said full area.

5. A perforating device according to claim 4 wherein the lower portion of the aperture of said plate has a first counterbore, the upper portion of said opening in said lower portion of said lower arm has a second counterbore, and such securing means includes a split ring element arranged in said counterbores.

6. A perforating device according to claim 5 which further comprises means arranged on said upper portion of said upper arm for removably locking a die in said die-receiving opening.

Description:
The present invention relates to improvements in a perforating device, and more particularly to a unit punch and die holder used in association with a press to punch a hole in a workpiece.

Such a holder includes an upper arm on which a punching and stripping assembly is mounted, and a lower arm supporting a die concentrically arranged with the punch of said assembly. Heretofore the lower arm of the holder was usually formed with an upwardly facing annular seat or shoulder for the lower end of the die which was cylindrical in form. The constant pounding of the punch against the workpiece, and the latter against the die in time distorted the die seat causing misalignment between the punch and die, resulting in excessive wear of the punch and die and generally unsatisfactory perforating. As well, such an arrangement limited the size of hole that could be punched on a given size of holder.

The present invention provides an improved perforating device or punch and die holder which overcomes the aforementioned disadvantages.

Accordingly, the primary objects of the present invention are to provide such a device or holder which affords stronger back up for the die so as to avoid distortion of the die seat, which is durable, which allows the die seat if it becomes excessively worn to be easily replaced without necessitating replacement of the entire device or holder, which prolongs the life of the punch and die, which is simple in construction and hence relatively inexpensive, and which allows larger perforations to be punched on a holder of a given size.

In accordance with the present invention, a perforating device including a holder having an upper stationary arm spaced above a lower stationary arm to provide a clearance therebetween, said upper arm having a bore for a punching and stripping assembly movable toward and from said clearance, is improved by providing a recess in said lower arm spaced below said clearance to leave an upper portion of said lower arm and a lower portion of said lower arm below said recess, said upper portion having a circumferentially continuously enclosed die-receiving opening extending between said clearance and recess, said lower portion having a slug-ejection opening extending from said recess, and an apertured die back-up member arranged in said recess and having an upwardly facing annular die-supporting surface.

Other objects and advantages of the present invention will be apparent from the following detailed description of a preferred embodiment illustrated in the accompanying drawings wherein:

FIG. 1 is a side elevational view, partly in section, illustrating a perforating device constructed according to the principles of the present invention.

FIG. 2 is a fragmentary enlarged horizontal sectional view thereof taken on line 2--2 of FIG. 1.

FIG. 3 is an enlarged exploded vertical sectional view of the lower arm of the holder and associated parts shown in FIG. 1.

FIG. 4 is a still further enlarged perspective view of the die back-up member and retaining ring shown in FIGS. 1.varies.3 but illustrated in a separated condition in FIG. 4, taken from a point of view looking upwardly at the bottom of this member and ring and located to one side of the same.

The number 10 represents generally a perforating device improved according to the present invention and is shown as including a holder 11 having an upper stationary horizontal arm 12 spaced above a lower stationary horizontal arm 13 to provide a clearance 14 therebetween at their free or separated ends and connected at their opposite ends by an integral connecting portion 15. Thus holder 11 is generally C-shaped in side appearance as viewed in FIG. 1. It is also preferably of uniform width in a horizontal transverse direction.

The free end portion 16 of upper arm 12 is shown as being offset downwardly slightly in relation to the main extent or length of this arm, and provided with a vertical through bore 18 in which is arranged a punching and stripping assembly, represented generally by the numeral 19, of any suitable construction. As shown, such assembly 19 includes a tubular guide 20 slidable in bore 18 between limits provided by the lower face of a flange 21 on the upper end of this guide and the upwardly facing lower end of a keyway or longitudinal slot 22 formed in the outside of this guide. A retainer 23 arranged in a recess 24 in the upper surface of arm end portion 16, and secured thereto as by a screw 25, has a key part projecting into keyway 22. The upper limit of movement of guide 20 is determined by retainer 23 engaging the lower end of keyway 22, as shown in FIG. 1, and the lower limit of movement of this guide is determined by this retainer engaging the lower face of flange 21.

Slidably arranged in the bore of guide 20 is a punch 26 having a reduced lower end portion 28, shown as being cylindrical, and a head 29 on its upper end. Arranged between head 29 and flange 21 is a stripping spring 30 helical in form and surrounding punch 26. Arranged between flange 21 and the upper surface of arm end portion 16 is a spiral lift spring 31 which surrounds guide 20.

The free end portion of lower arm 13 is shown as having an integral upwardly extending part indicated at 32. Extending horizontally across this part 32 the full width thereof between its vertical parallel side faces 37 and inwardly from the outer or front vertical end face 33 and terminating short of the inner or rear inclined end face 34, is a recess or slot 35. This forms an upper portion 36 and a lower portion 38 on lower arm 13. This slot 35 has a horizontal downwardly facing upper surface 39 and a horizontal upwardly facing lower surface 40.

Arm upper portion 36 is provided with a vertical cylindrical opening 41 extending therethrough from the top of raised arm part 32 to upper slot surface 39. This opening 41 receives a die 42 of cylindrical form having a vertical stepped bore 43 extending therethrough, the upper reduced portion 44 of which is concentric with the lower end portion 28 of punch 26 and is adapted to receive the same. It is to be noted that arm upper portion 36 circumferentially continuously surrounds die 42 when positioned in opening 41. This die 42, sometimes referred to as a die button in the trade, can be held against longitudinal and angular movement relative to the cylindrical wall of die-receiving opening 41, by a set screw 45 arranged in a threaded horizontal hole 46 in arm upper portion 36 arranged radially with respect to opening 41. When tightened, set screw 45 bears against the periphery of die 42.

Referring to FIG. 3, arm lower part 38 is shown as having a slug-ejection opening 48 extending vertically downwardly from slot lower surface 40. This opening 48 is shown as being cylindrical in shape, concentric with but of smaller diameter than die-receiving opening 41, and has a counterbored upper portion 49 still of smaller inside diameter than opening 41 for a purpose to be explained later herein. The lower end of opening 48 communicates with a recess 50 formed in front face 33.

An apertured die back-up member 51 is arranged in recess or slot 35. This member 51 is shown as being a plate having parallel upper and lower flat surfaces 52 and 53, respectively, and having a rectangular outline in plan formed by a parallel front and rear end faces 54 and 55, respectively, and parallel side faces 56. When in operative position in recess or slot 35, plate-like member 51 has its side faces 56 coterminous with side faces 37 of portion 32 of lower arm 13, as shown in FIG. 2, and its front face 54 coterminous with front face 33 of this portion as shown in FIG. 1.

The aperture in plate-like member 51 is a substantially central vertical through hole 58 having a counterbored lower portion 59 which extends for about half the thickness or height of this member. Hole 58 is shown as having the same diameter as opening 48. Counterbored portions 49 and 59 are shown as having the same diameter.

Means for removably securing member 51 to lower arm 13 are provided. While these means may be variously constructed the same is shown as comprising a split ring element 60 in the form of a split band. This band 60 has a height substantially that of the sum of the axial depths of counterbored portions 49 and 59 so that it may be arranged between the opposing shoulders thereof as shown in FIG. 1. In this position, band 60 straddles the joint formed by opposing and contacting surfaces 40 and 53 and prevents withdrawal of member 51 from recess or slot 35. Preferably as shown, band 60 has a wall thickness no greater than the radial depth of counterbored portions 49 and 59 so that it will not project inwardly of aligned openings 48 and 58.

Split band 60 may be inserted and removed through either opening 48 or 58 by collapsing the band to reduce its outside diameter enough to pass through either opening 48 or 58. When opposite counterbored portions 49 and 59 and released, the inherent resilience in band 60 will cause it to enlarge or expand diametrically and fit into these counterbored portions in interlocking fashion.

Referring to FIGS. 1 and 3, it will be seen that the lower flat end face 47 of die 42 is adapted to sit on or engage an annular upper surface portion 52' of member 51 surrounding aperture 58 therein. This portion 52' provides a seat for die 42.

Lower arm 13 may have one or more pilot pins 61 for positioning the holder 11 in a template (not shown).

As is understood by those skilled in the art, one or more devices 10 arranged in predetermined spaced relation may be placed between the bed and ram of a press (not shown) so that with a workpiece (not shown) interposed between die 42 and assembly 19 when the press is operated the ram will engage punch heads 29 driving each assembly downwardly and through spring 30 also guide 20 compressing lifter spring 31 until this guide engages the workpiece. Following this continued downward drive on the punch compresses spring 30 and projects the lower end 28 of the punch from guide 20 into and through the workpiece and into die hole 44, thereby striking out a slug of material which falls through openings 43, 48 and 50. During such punching operation, it will be noted that the punching force is resisted by die seat 52'. Raising the ram allows stripper spring 30 to withdraw the previously projected lower end 28 of punch 26 from the hole punched in the workpiece and into guide 20. Lifter spring 31 then expands to raise assembly 19 as a whole relative to upper arm 12 and restore this assembly to the condition depicted in FIG. 1.

An important feature of the present invention is to construct die back-up member 51 of a material harder and stronger than that of which holder 11 is composed. For example, cast iron is one material from which to make holder 11 because it is relatively easy to machine and provides a good wear surface for bore 18 for guiding assembly 19. However, a die seat 52' made of cast iron will break. If a substitute material such as cast steel is used for the holder, it is more difficult to machine and also will yield and deform if providing die seat 52'. Providing a holder entirely of a hardened steel material is 163 prohibitively expensive. In order to overcome this dilemna and in accordance with the present invention the main body of holder 11 is made of a suitable and economically feasible material such as cast iron, aluminum alloy for reduced weight if desired, or is pressure cast from zinc alloys, or is molded from high strength plastic material, while die back-up member 51 is provided composed of a harder or stronger material such as a hard steel. While the lower end face 47 of die 42 is supported by seat surface 52', this surface in area is smaller than that of the back-up area 40 for member 51 which engages the full area of its lower surface 53. Thus the member 13 made of the softer and weaker material backs up over a larger area (surface 40) the member 51 having the harder and stronger material effective over the small area (seat 52') for backing up the die 42, in opposing the punching load or force.