US3670613A

US3670613A - Punch stripper

Info

Publication number: US3670613A
Application number: US66363A
Authority: US
Inventors: Dominick Rienzi
Original assignee: Individual
Current assignee: Individual
Priority date: 1970-08-24
Filing date: 1970-08-24
Publication date: 1972-06-20
Anticipated expiration: 1989-06-20

Abstract

A punch stripper unit comprising an integral polyurethane body member having a steel band embedded therein which reinforces the body member and threadingly receives locking screws for securing a punch in a punch receiving hole passing through the body member. The polyurethane provides its own spring-back force when compressed during a punching operation to forcibly remove a punch member mounted in the stripper unit from a punched hole. The workpiece engaging surface of the polyurethane body does not mar workpieces being punched since polyurethane is non-abrasive. Further, an oil retaining reservoir in the form of a groove formed around the outside of the stripper unit communicates with the punch receiving hole via lubricating channels for continuously supplying lubricant between the surface of the punch receiving hole and a punch disposed therein. In addition, oil collecting means may be provided for lubricating the walls of the punching end of the punch for facilitating punching of a workpiece.

Description

[4 June 20, 1972,

[54] PUNCH STRIPPER [72] Inventor: Dominick Rienzi, 15 Jefferson St., Nutley,

22 Filed: Aug. 24, 1970 21 Appl,No.: 66,363

[52] US. Cl ..83/139, 83/169, 83/698 [51] Int. Cl. ..B26d 7/06, B26d 7/18 [58] Field ofSearch ..83/139, 169,698

[56] References Cited UNITED STATES PATENTS 2,815,814 12/1957 Taylor ..L 83/139 3,269,238 8/1966 Whistler, Sr. et a1. ..83/139 Primary Examiner-F rank T. Yost Attorney+bemen David & Littenber'g 57 ABSTRACT A punch stripper unit comprising an integralpolyurethane body member having a steel band embedded therein which reinforces the body member and threadingly receives locking screws for securing a punch in a punch receiving hole passing through the body member. The polyurethane provides its own spring-back force when compressed during a-punching operation to forcibly remove a punch member mounted in the stripper unit from a punched hole. The workpiece engaging surface of the polyurethane body does not mar workpieces being punched since polyurethane is non-abrasive; Further, an oil retaining reservoir in the form of a groove formed around the outside of the stripper unit communicates with the punch receiving hole via lubricating channels for continuously supplying lubricant between the surface of the punch receiving hole and a punch disposed therein. In addition, oil collecting means may be provided for lubricating the walls of the punching end of the punch for facilitating punching of a workpiece.

15 Claims, 7 Drawing figures 1,822,468 9/1931 Wales 1,510,008 9/1924 R17,905 12/1930 Wright ..83/169X 2,867,276 1/1959 Taylor ..83/139 3,178,106 4/1965 JoneS,Jr. ..83/169X PATENTEDmzo m2 SHEET 10F 3 27. FIG. 1

INVENTOR.

DOM/NICK RIENZI LERNER, DAVID 8 LITTENBERG AT TORNE YS PKTENTEBmzo m2 3.670.613

' sum 20F 3 INVENTOR.

DOM/NICK RIENZI L ERNER, DAVID a L ITTENBERG ATTORNEYS PATENTEBJum nan sum 3 or a;

FIG. 6"

INVENTOR.

E N M E m n R L K a m m N v w m D Q m Y u ATTORNEYS PUNCH STRIPPER BACKGROUND OF THE INVENTION Stripper units for punches and the like are of course quite well known. They are used to provide a positive punch removing force for forcing a punch out of a hole it has formed immediately subsequent to the punching operation forming the hole. In addition, they may serve to guide a punch in a desired path when mounted in, for example, a punch and dye bushing retainer unit or the like. The punch stripper unit may comprise, for example, for mounting of a punch therein, a punch receiving hole which passes entirely through the punch stripper unit and locking means for retaining the punch in a desired position within the punch receiving hole. The locking means may, again by way of example, comprise locking screws.

Known means for generating the punch removal, force for stripping a punch from a workpiece, or vice versa, comprise springs which are compressed during the punching action and, immediately subsequent to the removal of the punching force, expand forcing the punch out of the hole it has formed. In place of springs, a portion or portions of the stripper unit may be made of a resilient material, such as polyurethane. Though known stripper units employing springs have provided generally satisfactory'performance, there are always the problems inherent in such units, such as the need to replace broken springs, damage due to loosened shoulder bolts, the need to replace stripper plates, etc. Stripper units comprising resilient portions also have provided generally satisfactory performance but suffer from similar problems, except of course for the fact that there are no broken springs. In addition, there is always room for improvement in unit performance, unit life, simplicity of manufacture, and costs.

It is the general object of this invention to provide a stripper unit which does not suffer from the above-noted disadvantages. It is a further general object of this invention to provide such a stripper unit which will have improved operating characteristics, such as automatic lubrication and non-abrasiveness, will be simple and relatively inexpensive to manufacture, and will have a long useful life.

SUMMARY OF THE PRESENT INVENTION preferred that the plastic material be of the type which will not abrade so that highly polished pieces, such as polished brass, can be punched without scratching or marring the surface thereof. Polyurethane has been found to be particularly desirable because of its many desirable characteristics, such as its durability, resiliency, imperviousness to heat, cold, oils, 6iC..

According to the present invention, the integral stripper unit as described directly above may be formed with a metal reinforcing band embedded in the plastic material and provided with threaded holes for receiving locking screws. Still further, the stripper unit of this invention may be provided with a lubrication reservoir communicating with a punch receiving hole thereof via lubricant channels for continuously supplying lubricant to the space between a punch disposed in the hole and the inner surface of the punch receiving hole. The lubricant can be for reciprocal movement of the punch relative to the stripper unit and/or for facilitating punching of a hole in a workpiece. In the first instance, the lubricant would be supplied between the punch body and the stripper unit while in the second instance the lubricant would be supplied to the punching end of the punch so that the portion engaging the workpiece would be lubricated.

More specifically, according to the present invention, there is provided a punch stripper unit comprising an integral body member made of substantially rigid, resilient plastic material, said body member comprising a punch receiving portion and a BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a first embodiment of a punch stripper unit in accordance with the present invention;

FIG. 2 is a side elevational cross-sectional view of the punch stripper unit of FIG. 1;

FIG. 3 is a cross-sectional view of a second embodiment of a punch stripper unit in accordance with the present invention taken along the lines 33 of FIG. 4;

FIG. 4 is a plan view of the punch. stripper unit of FIG. 3;

FIG. 5 is a side elevational view of a punch adapted for use with the punch stripper unit of FIGS. 3 and 4;

FIG. 6 is a cross-sectional view of a third embodiment of a punch stripper unit in accordance with the present invention taken along the lines 6-6 of FIG. 7; and

FIG. 7 is a plan view of the punch stripper unit of FIG. 6.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings in which like reference numerals refer to similar parts throughout, a presently preferred embodiment of a cylindrical punch stripper unit 10 in accordance with the invention is shown in FIGS. 1 and 2. Punch stripper units in accordance with the invention may of course take many different forms, such as square, rectangular, oblong, and irregular form,etc. The unit 10 comprises an integral body member 1 1 made of substantially rigid, resilient plastic materi a]. The presently preferred body member 11 is made of polyurethane.

The body member 11 is formed with a substantially circular punch receiving and retaining hole 12. The unit 10 is also formed with a metal band 13 embedded in the plastic material of the body member 11 and symmetrically and annularly disposed about punch receiving hole 12. Four lock screws 14 (only three being shown) are disposed in screwdriver or the like receiving holes 16 symmetrically positioned about punch receiving hole 12 to symmetrically grip a punch (not shown) which may be disposed within the punch receiving hole 12. Number, size andtypes of screws and their locations may vary whether placed symmetrically or otherwise.

The unit may be made in any well known manner, such as by molding the body member 11 with the metal band 13 held machined to its desired configuration. The top of the unit.

where the metal band 13 is may be machined down to the band and the exposed surface of the: band used for the stamping of identifying indicia thereon. As indicated, other known and acceptable methods of manufacture may be employed.

The metal band 13, which in the preferred embodiment is made of steel, has threaded holes 18 which threadingly receive the lock screws 14 thus providing a secure means for mounting of the lock screws 14. In addition, the metal band 13 strengthens the unit 10.

The metal band 13 is embedded in an upper portion 20 of the body member 11 which is largerin cross-section than the remainder of the unit 10. The upper portion 20 may be formed, for example, to be matingly and slidingly received in a be deposed with its punching end extending below the unit or disposed within the unit itself since upon compression of the unit, the punching end would extend below the unit. The punch would also have a clamping end which would extend above the unit 10 and be used for clamping of the assembled punch and unit 10 in a punch retainer unit. During a punching operation, the assembled punch retainer unit, punch stripper unit 10, and punch would be moved towards a workpiece causing the punch to punch a hole in the workpiece at which time the lower or workpiece engaging surface 22 of punch stripper unit 10 engages the workpiece surface.

The body member 11 will be compressed during the punching movement. Upon removal of the punching force, the body member 11 springs back to its original shape popping the punch out of the punched hole. This is commonly called stripping in that the workpiece is stripped from the punch or vice versa.

The integral body member 11 further comprises a reduced diameter portion 25, an annularly flanged portion 24, and a bottom portion 27. The flanged portion 24 has an annular groove 26 formed in its upper surface as viewed in the drawings. The groove 26 may serve as a lubricant reservoir, such as an oil reservoir. In this regard, it will be noted that the outside diameter of the annular portion 24 is approximately equal to the outside diameter of the upper portion 20. Thus, if, for example, oil is disposed in the groove 26 and the stripper unit 10 is retained in a mating cylindrical hole of a punch retaining unit or the like, the oil in the groove 26 will be retained in the chamber formed by the wall of the mating cylindrical hole, the lower surface of upper portion 20, the outer surface of reduced diameter portion 25, and the upper surface and groove 26 of flanged portion 24.

Lubricant channels 28 lead from groove 26 to lubricant holes 30 in the surface 32 of punch receiving hole 12. By means of the groove 26, lubricant channels 28, and lubricant holes 30, lubricant in groove 26 will be continuously fed between the surface of a punch disposed within punch receiving hole 12 and the hole surface 32.

A second presently preferred embodiment of a punch stripper unit 34 in accordance with the invention is shown in FIGS. 3 and 4. The unit 34 differs from the unit 10 in that there is no bottom portion 27 disposed below the annularly flanged portion 24. In addition, and more importantly, an annularly inwardly extending portion 36 partially seals the bottom of punch receiving hole 12. The lubricating channels 28 lead to a groove 30 formed in the annular portion 36. This leaves a raised portion 37 extending about a punch end guiding hole 13 defined by annular portion 36.

A punch 39 adapted for use with punch stripper unit 34 is shown in FIG. 5. Punch 39 comprises a main body portion 47 having a recessed portion 41 formed therein for facilitating movement of punch 39 within a closely fitting cylindrical cavity, such as the cavity presented by punch receiving hole 12. Punch 39 further comprises a greatly reduced diameter punching end 43 which is connected to the main body portion 47 by a smoothly contoured portion 45.

When the punch 39 is disposed within punch receiving hole 12 of unit 34, punch end 43 extends slightly below or above workpiece engaging surface 22. During compression of unit 34 upon punching of a workpiece, lubricant in groove 38 is forced out of the groove and into contact with the contoured portion 45 of punch 39. This occurs during each punching operation and thereby repeatedly and thus continuously lubricates the contoured portion 45 and thereby the punch end 43 during continuous punching operations to provide improved punch performance. Thus, lubricant is directly and automatically and continuously supplied to the punching end 43 and contoured portion 45 when utilizing unit 34. It is to be noted in this regard that lubricant also reaches the punching end of a punch when utilizing unit 10 shown in FIGS. 1 and 2 since it will work its way down the punch due to the force of gravity.

A presently preferred third embodiment of a punch stripper unit 40 in accordance with the present invention is shown in FIGS. 6 and 7. Unit 40 differs from unit 10 in that it is adapted to accommodate five separate punches in punch receiving holes 12. Further, recesses 50 have been formed in body member 11 to take up compression and avoid binding of the unit 40 in a punch and dye retaining unit or the like during a punching operation. It will be appreciated in this regard that the material, such as polyurethane, of the body 11 expands outward during axial compression. This outward expansion is accommodated in all of the units by the reduced diameter portion 25. In the multi-prone unit 40, the recesses 50 are additionally provided to aid in preventing distortion of any of the plurality of punch receiving holes 12.

The smaller four holes 12 surrounding the larger hole 12 comprise counterbored portions 44 and 46 which leave an annular portion 48 defining a punch guiding surface 42. The counterbored portions 44 and 46 are provided to take up compression and avoid binding of a punch disposed within their respective holes 12.

Lubricating channels 28 leadfrom a common groove 26 to all of punch receiving holes 12. However, lock screws 14 are only provided for cooperation with a punch disposed within the larger central punch receiving hole 12. Mounting of the unit 40 on a punch disposed in the larger central punch receiving hole 12 would automatically align the remaining four punches in the remaining smaller holes 12.

Punch stripper units made in accordance with the present invention have been found to possess many advantages over present stripper units. For example, they have much longer useful lives (up to two times longer than the best known present stripper units); they can be used to strip varied metal thicknesses; they provide greater compression travel than possible with present stripper units; they are extremely safe (they are light weight and have no sharp edges); they greatly reduce punch noise; they do not mar workpiece surfaces, and they can withstand rough handling without damage.

The present description has been by way of example and is not intended, in any way, as a limitation to the scope of the invention as defined in the appended claims. For example, it may be that a punch stripper unit in accordance with the present invention may be made of a plastic material having properties which will obviate the need for a metal band member. Similarly many different shapes of the unit 10 and oil reservoir 26 are possible within the spirit and scope of the invention.

I claim as my invention:

1. A punch stripper unit comprising an integral body member made of substantially rigid, resilient plastic material, said body member comprising a punch receiving portion and a work piece engaging portion, means for retaining a punch in said punch receiving portion, said punch retaining means comprising lock screws and metal means for threadingly receiving said lock screws.

2. A unit according to claim 1, wherein said metal means comprises a metal band embedded in the plastic material of said body member.

3. A unit according to claim 2, wherein said metal band is made of steel.

4. A unit according to claim 3, wherein said punch receiving portion of said body member comprises a substantially circular hole formed therethrough, and said metal band is symmetrically disposed within said body member about said hole.

5. A punch stripper unit comprising an integral body member made of substantially rigid, resilient plastic material, said body member comprising a punch receiving portion and a work piece engaging portion, means for retaining a punch in said punch receiving portion, said punch receiving portion comprising a punch receiving hole passing through said body member, and said body member further comprising lubricant storage means for storing lubricant and continuously supplying it to the innersurface defined by said punch receiving hole.

6. A unit according to claim 5, wherein said lubricant storage means comprises a groove formed in said integral body member and lubricant channels leading from said groove to lubricating holes formed in the inner surface defined by said punch receiving hole.

7. A unit according to claim 6, wherein said punch receiving hole is substantially circular in cross-section, said body member comprises an upper portion which is substantially annular in cross-section, a reduced outer diameter annular middle portion adjacent said upper portion, and a lower flangelike annular portion adjacent said middle section and having an outer diameter substantially equal to the outer diameter of said upper portion, and said groove is formed in the upper sur face of said flange-like portion.

8. A unit according to claim 7, wherein said lubricating channels comprise channels leading downwardly from said groove to said lubricating holes.

9. A unit according to claim 6, wherein said body member comprises an upper portion; a middle portion adjacent said upper portion and having a reduced outer periphery in relation to said upper portion, and a lower portion adjacent said middle portion and having an outer periphery substantially congruent with that of said upper portion, and said groove is formed in the upper surface of said lower portion which surface is defined by the differences between the outer peripheries of the middle and lower portions.

10. A unit according to claim 9, wherein said plastic material is polyurethane, said punch retaining means comprises lock screws and a metal band embedded in said plastic material and threadingly receiving said lock screws, said metal band being disposed about said punch receiving hole, and said workpiece engaging portion comprises a bottom portion disposed adjacent said lower portion which bottom portion comprises a flat lower workpiece engaging surface.

11. A unit according to claim 5, wherein said lubricant storage means further comprises means for supplying lubricant to the punching end of a punch disposed within said punch receiving hole.

12. A unit according to claim 11, wherein said means for supplying lubricant to said punching end of a punch comprises an integral inwardly extending portion of said body member which partially closes off the punching end receiving end of said punch receiving hole, said integral inwardly extending portion defining a punch end guiding hole.

13. A unit according to claim 12, wherein said integral inwardly extending portion further comprises a recess for retaining lubricant and said inwardly extending portion is adapted to cooperate with said recess to supply lubricant to said punch end guiding hole during axial compression of the said punch stripper unit.

14. A punch stripper unit comprising a punch receiving portion defining a punch hole, a work piece engaging portion, means for retaining a punch in said punch receiving hole, lubricant storage means for storing lubricant and continuously supply it to said punch receiving hole, said lubricant storage means comprising a groove formed in said punch receiving portion and lubricant channels leading from said groove to said punch receiving hole. r

15. A unit according to claim 14, wherein said groove is formed in an upper surface of said punch receiving portion.

Claims

3. A unit according to claim 2, wherein said metal band is made of steel.

7. A unit according to claim 6, wherein said punch receiving hole is substantially circular in cross-section, said body member comprises an upper portion which is substantially annular in cross-section, a reduced outer diameter annular middle portion adjacent said upper portion, and a lower flange-like annular portion adjacent said middle section and having an outer diameter substantially equal to the outer diameter of said upper portion, and said groove is formed in the upper surface of said flange-like portion.

9. A unit according to claim 6, wherein said body member comprises an upper portion, a middle portion adjacent said upper portion and having a reduced outer periphery in relation to said upper portion, and a lower portion adjacent said middle portion and having an outer periphery substantially congruent with that of said upper portion, and said groove is formed in the upper surface of said lower portion which surface is defined by the differences between the outer peripheries of the middle and lower portions.

14. A punch stripper unit comprising a punch receiving portion defining a punch hole, a work piece engaging portion, means for retaining a punch in said punch receiving hole, lubricant storage means for storing lubricant and continuously supply it to said punch receiving hole, said lubricant storage means comprising a groove formed in said punch receiving portion and lubricant channels leading from said groove to said punch receiving hole.