US3269238A

US3269238A - Punch stripper apparatus

Info

Publication number: US3269238A
Application number: US415250A
Authority: US
Inventors: Sr Lawrence V Whistler; Jr Lawrence V Whistler
Original assignee: Individual
Current assignee: Individual
Priority date: 1964-12-02
Filing date: 1964-12-02
Publication date: 1966-08-30
Anticipated expiration: 1983-08-30
Also published as: FR1456310A; DE1527063A1; GB1061517A

Description

30, 1966 L. v. WHISTLER, SR, ETAL 3, 69, 38

PUNCH S TRIPPER APPARATUS 2 Sheets-Sheet 1 Filed Dec. 2, 19 4 Wm vm INVENTORS, Lfiwnewca WHISTLER, SR.

L-fl UHcsrLE, J1.

BY awn-1 ATTORNEYS Aug. 30, 1966 v w s 5 ET AL 3,269,238

PUNCH STRIPPER APPARATUS 2 Sheets-Sheet 2 Filed Dec. 2, 1964 o INVENTOR 8, AM/Reva ld nsnsz 82.

Ow V S QM L mm M U J E C N E M F A M Q B United States Patent Office amazes Patented August 30, 1965 PUNCH STRIPPER APPARATUS Lawrence V. Whistler, Sr., 251 Doncaster Road, and Lawrence V. Whistler, In, 259 Doncaster Road, both of Kenmore, NCY.

Filed Dec. 2, 1964, Ser. No. 415,250 8 Claims. (Cl. 83-139) The present invention relates to new and novel punch stripper apparatus and more particularly to a stripper device incorporating a novel retainer means arrangement for mounting the stripper means in operative position in surrounding relationship to a punch and the like.

The stripper arrangement of the present invention is so constructed and arranged as to be utilized with punches such as those used in piercing, perforating, notching operations and the like, wherein the stripper device strips off the workpiece in a well known manner.

The present invention contemplates the use of a stripper device incorporating a body of elastic material such as polyurethane and the like or a more conventional type arrangement wherein compression spring means is employed.

Stripper devices of the type according to the present invention have been secured in operative position about an associated punch in a variety of manners. In some instances, the stripper device is mechanically locked in place by means of a set screw or similar arrangement. In some instances, the punch may be provided with a peripheral groove for receiving a suitable attaching means for securing the stripper device in operative position.

In the present invention, no alteration or change of a conventional punch is required, and the stripper device may be quickly and easily mounted in operative position simply by slipping the device into its operative clamping position by sliding it over the punch.

While it is highly desirable to provide a punch stripper device which can be easily moved into operative position, the same stripper device should remain in operative position, and accordingly, it is desirable to provide an arrangement whereby a considerable amount of force is required to remove the stripper device.

Additionally, it is important to provide an arrangement wherein the stripper apparatus retaining means provides constant holding power regardless of the position on the punch. In other words, the same amount of force should be required for removing the stripper device throughout the length of the portion of the punch upon which the stripper device is adapted to be mounted.

Another important consideration is the fact that punches employed in this type of operation often have the surface thereof covered with oil or grease and other kinds of lubricants. The retaining arrangement should be such that the same amount of force is required to remove the stripper apparatus once it is in operative position regardless of whether the punch is dry or is provided with some sort of a lubricating substance on the outer surface thereof.

In the arrangement of the present invention, a unique retainer means is employed which permits the stripper apparatus to be readily mounted in operative position on a punch simply by sliding the stripper apparatus into its operative position. A considerable amount of force is required to remove the stripper apparatus from an associated punch, but it can be readily manually removed preferably by twisting the apparatus with respect to the punch and pulling it downwardly away from the punch.

The retainer means of the present invention provides a constant holding power regardless of the position of the stripper apparatus of the punch, and furthermore this holding power is not aflected by the presence of lubricants on the outer surface of the punch.

The retainer means itself comprises a flat disc-like one-piece construction formed of relatively rigid resilient material wherein the inner area thereof is provided with a plurality of angularly spaced radially inwardly extending portions the inner ends of which define a central hole which is undersized to the punch for snugly receiving the punch and clamping the punch stripper apparatus in operative position on the punch. Means is incorporated in the stripper apparatus for permitting flexing of the inner part of the retainer means so that it can readily move into its operative clamping position.

This construction also permits the holding force to be predetermined and the holding force of the retainer means can be varied by changing certain critical dimensions thereof thereby affording great versatility to this arrangement.

A particularly important economic advantage of the present invention is the fact that the structure for holding the stripper apparatus in operative position is extremely simple and inexpensive so that it alfords considerable savings in cost while at the same time affording maximum utility and a most practical arrangement.

An object of the present invention is to provide new and novel punch stripper apparatus for stripping off work from punches utilized for example in piercing, perforating and notching operations and the like.

Another object of the invention is the provision of punch stripper apparatus incorporating retaining means for quickly and easily mounting the stripper device on a punch and for securely retaining the stripper device in operative position.

Still another object of the invention is to provide punch stripper apparatus incorporating retainer means which provides a substantially constant holding power regardless of the position of the stripper apparatus on the punch, and further wherein considerable force is required to remove the stripper apparatus from the punch.

Still another object of the invention is the provision of punch stripper apparatus incorporating retainer means providing a substantially constant holding power on the punch which is not materially aflFected by the presence of lubricants or the like on the outer surface of the punch.

Still another object of the present invention is to provide punch stripper apparatus incorporating retainer means of such a construction that the holding force can be predetermined and readily obtained by altering the dimensions of the retainer means.

A still further object of the invention is the provision of punch stripper apparatus which is quite simple and inexpensive in construction and yet is at the same time eificient and reliable in use.

Other objects and many attendant advantages of the invention will become more apparent when considered in connection with the specification and accompanying drawings, wherein:

FIG. 1 is a vertical section through punch stripper apparatus according to the present invention prior to its installation on an associated punch;

FIG. 2 is a sectional View through a punch and die assembly with the stripper apparatus of the present invention illustrated in operative position on the punch of the arrangement;

FIG. 3 is a sectional view taken substantially along line 33 of FIG. 1 looking in the direction of the arrows;

FIG. 4 is an enlarged sectional view of a portion of the punch stripper apparatus of the present invention illustrating the manner in which the retainer means is adapted to flex into its operative clamping position;

FIG. 5 illustrates the position of the retainer means as the punch stripper apparatus of the present invention is being removed from an associated punch;

FIG. 6 is a vertical section through a modified form of the invention; and

FIG. 7 is a sectional view taken substantially along line 77 of FIG. 6 looking in the direction of the arrows.

Referring now particularly to FIGS. 1-5 inclusive, a first modification of the invention is illustrated wherein a punch holder 10 supports a punch retaining pad 12, retaining screws 14 being employed for holding the punch retaining pad in operative position, and dowel pins 16 being provided for properly aligning the punch retaining pad in a conventional manner.

A punch indicated generally by reference numeral 20 is inserted in the usual punch receiving hole 21 provided in punch retaining pad 12, a hardened back-up plate 22 being provided against which the upper end of the punch rests. The punch may be retained within the punch retaining pad in any suitable conventional manner (not shown) such as a set screw or the like for holding the punch in position.

Punch 20 includes a general cylindrical portion 26 and a lower working end portion 28 as seen in FIG. 2, and the punch stripper apparatus of the present invention is illustrated generally by reference numeral 30 and is adapted to be mounted in surrounding relationship to the punch.

A die holder 32 is adapted to support a die retaining pad 34, the die retaining pad being held in place by retaining screws 36 and properly aligned by dowel pins 38 in the usual manner. A die bushing 40 is mounted within the usual hole 42 provided in the die retaining pad 34. The construction and arrangement of the punch and die mounting means is of a conventional construction, and forms no part of the present invention.

The novel punch stripper apparatus of the present invention indicated generally by reference numeral 30 includes a first relatively rigid end portion 50 and a second relatively rigid end portion 52, a resilient means 54 being interposed between the opposite end portions and in engagement therewith. The body of elastic material 54 may comprise a polyurethane plastic which is of generally annular construction having an outer cylindrical configuration with a longitudinally extending bore 56 formed therethrough.

The end portion 50 is provided with a recess 60 opening downwardly therefrom as seen in FIG. 1, a bead 62 being formed peripherally about the bottom portion of the recess and extending inwardly therefrom so as to retain the upper portion of the elastic body portion 54 snugly within the recess in the end portion 50 and to lock the end portion onto the body portion 54. The recess 60 includes a bottom wall portion 64 which is substantially flat for a purpose hereinafter described, and end member 50 is provided with a central hole 66 formed therethrough which is in communication with the recess 60.

The opposite end portion 52 is provided with a recess 70 for receiving the lower end of the body portion 54, and a radially inwardly extending beam 72 extends peripherally around the upper portion of the recess as seen in FIG. 1 for retaining the end portion 52 on the lower end of the body portion 54. End portion 52 is also provided with a central hole 74 formed therethrough. It will be noted that the bore 56 as well as the

holes

66 and 74 are aligned with one another so as to receive a punch therewithin when the stripper apparatus is mounted in operative position as shown in FIG. 2. Each of the

end portions

50 and 52 may be formed of a suitable relatively rigid material such as mild steel. The retainer means of this modification is indicated generally by reference numeral 80, the retainer means being formed for example of tempered spring steel having a thickness of approximately .005 of an inch.. Accordingly, this retainer means is formed of a relatively rigid yet resilient material and comprises a flat, disc-like one-piece member. This flat member is adapted to rest against the flat bottom wall 64 of recess so as to normally hold the retainer means in a flat planar position as seen in FIG. 1.

Referring particularly to FIG. 3, the configuration of retainer means may be seen more clearly. The retainer means has an outer periphery which is generally smaller than the periphery of the inner wall 78 of the recess 60. The retainer means is provided with a plurality of outwardly extending projections 82 shown as being three in number and angularly spaced an equal amount from one another, these projections 82 engaging the wall 78 for holding the retainer means in proper centered relationship within the recess. The retainer means is preferably a slip fit within the recess 60.

The inner area of the retainer means is provided with a plurality of radially extending slots 83 which divide such inner area into a plurality of angularly spaced radially inwandly extending portions 84, the inner ends 86 of which define a circular area within which the punch is adapted to fit. This central hole defined by the inner ends 86 of the portions 84 of the retainer means is slightly undersized to the punch .so as to snugly fit thereon.

In a typical example wherein the punch portion 26 has a diameter of .500' inch, the hole 66 in end portion 50 may have a diameter of approximately .502 inch, and the bore 56 formed within the elastic body portion 54 may have a diameter of approximately .510 inch, while the central hole defined within the retainer means for receiving the punch may have a diameter of approximately .497 inch.

When the punch stripper apparatus is moved into the operative position illustrated in FIGS. 2 and 4 wherein the upper surface of end portion 50 is disposed against the undersurface of punch retaining pad 12, the retainer means 80 is caused to move into the position shown in FIGS. 2 and 4 wherein the inner parts of portions 84 of the retainer means are flexed downwardly, the resilient material of body portion 54 permitting such flexing into the position shown in FIGS. 2 and 4. It will be noted in this position as shown in FIG. 4 that the relatively sharp edges 80 formed at the upper part of portions 84 engage the outer surface of the punch for retaining the stripper apparatus in operative position. When the stripper apparatus is pulled downwandly to remove the stripper apparatus from the punch, the retainer means moves into the position shown in FIG. 5 wherein it tends to become substantially flat, the flat bottom wall 64 of the recess serving to prevent the retainer means inner portions from flexing into an opposite position from that shown in FIGS. 2 and 4, and causing a considerable amount of force to be required for removing the stripper apparatus.

Referring now to FIGS. 6 and 7 of the drawings, a modified form of the invention is illustrated wherein a punch retainer is provided, this punch retainer being of a magnetic type which is adapted to be magnetically adhered to the punch holder. A piercing punch 102 is provided which may be substantially identical with the punch 20 previously discussed. The punch is provided with a suitable notch 103 formed in one side thereof for receiving a set screw 104 threaded within a suitable opening provided in the punch retainer 100 for securing the punch in operative position within the punch retainer in a well known manner.

The stripper apparatus itself is indicated generally by reference numeral and includes a stripper adaptor 112. A plurality of retainer bolts 114 are slidably mounted within suitable countersunk openings 115 provided in the stripper adaptor, the retainer bolts 114 supporting at the lower ends thereof a stripper plate 116. Conventional coil springs 118 are provided around the retainer bolts and are adapted to urge the stripper plate 116 in a downward direction after it has been moved upwardly during a piercing operation so as to subsequently strip off the workpiece. Stripper adaptor 112 and the stripper plate 116 are provided with aligned

openings

120 and 122 formed therethrough for receiving the adjacent portions of the punch.

Stripper adaptor 112 is provided with a recess 130 in the upper surface thereof which is adapted to receive a retainer means indicated generally by reference numeral 132. This retainer means is also of a fiat disc-like onepiece construction and is formed of a material similar to the retainer means 80 previously discussed. A flat retainer cap 134 is disposed over retainer means 132, the flat undersurface of cap 134 engaging the upper surface of the retainer means. Retainer cap is retained in position by means of flat head screws 136 extending through suitable openings provided in

members

134 and 112, and.

a central hole 138 is formed through cap 134 for receiving the punch.

As seen particularly in FIG. 6, the upper inner portion of stripper adaptor 112 is cut away or beveled as indicated by reference numerals 140 so as to provide an annular downwardly tapering shoulder which is in communication with the central part of recess 130. This cut away portion 140 permits downward flexing of the inner part of the retainer means so that it can move into the operative position shown in FIG. 6 which is similar to that previously discussed wherein the inner portions of the retainer means are flexed downwardly when the retainer means is in operative clamping position about a punch.

Referring now particularly to FIG. 7, the configuration of the retainer means 132 may be more clearly seen. The outer peripheral surface of the retainer means is of substantially elliptical configuration so that the outer surface of the retainer means engages the inner wall of the recess 130 at two diametrically opposite points of the substantially circular recess. Here again, the retainer means is substantially a slip fit within the recess provided in the stripper adaptor. The inner area of the retainer means 132 is provided with a plurality of radially extending slots 144 which divide this inner area of the retainer means into a plurality of angularly spaced radially inwardly extending portions 146 the inner ends 148 of which define a central circular hole for receiving a punch. As in the previous modification, the central hole provided within the retainer means is undersized to the punch so that the punch may be tightly gripped by the retainer means for holding the punch stripper apparatus in operative position.

It will be apparent that in each of the modifications, the provision of the radially extending slots in the retainer means provides greater resilience to the inner area of the retainer means so that it can flex into the operative position as illustrated in the drawings. It should also be understood that each of the modifications of the invention operates in a similar manner to provide the new and improved results as aforesaid.

It is apparent from the foregoing that there is provided according to the present invention new and novel punch stripper apparatus for stripping ofl work from punches utilized in piercing, perforating, notching operations and the like. The invention incorporates retainer means for permitting quick and easy mounting of the stripper apparatus on the punch and for securely retaining the stripper apparatus in operative position. The retainer means of the present invention provides a substantially constant holding power regardless of the position of the stripper apparatus of the punch, and considerable force is required for removing the stripper apparatus from an associated punch. In addition, the holding power of this type of retainer means is not materially affected by the presence of lubricants and the like on the outer surface of the punch. The holding force of the retainer means may be readily adjusted by varying the size of the hole defined in the central area of the retainer means or by increasing or diminishing the thickness of the retainer means. It is accordingly apparent that slight changes in the dimensions of the retainer means can be made so as to substantially alter the amount of holding force of the retainer means. In a typical example, wherein the dimensions are as aforesaid, regarding the diameter of the punch and the hole provided in the retainer means, and wherein the retainer means has a thickness of approximately .005 of an inch, a force of 30 to 40 pounds is required for removing the stripper apparatus from an associated punch. It is also apparent that the arrangement of the present invention is quite simple and inexpensive in construction, and yet is quite efiicient and reliable in use.

As this invention may be embodied in several forms without departing from the spirit or essential characteristics thereof, the present embodiment is therefore illustrative and not restrictive, and since the scope of the invention is defined by the appended claims, all changes that fall within the metes and bounds of the claims or that form their functional as well as conjointly cooperative equivalents are therefore intended to be embraced by those claims.

We claim:

1. Punch stripper apparatus comprising a first relatively rigid end portion and a second relatively rigid end portion spaced from said first end portion, each of said end portions having a central hole formed therethrough for receiving a portion of a punch, resilient means interposed between and engaging said first and second end portions, said resilient means defining a central clearance area for receiving a punch, and retainer means adjacent said first end portion for retaining the stripper appaartus on a punch, said retainer means being formed of a relatively rigid resilient material, said retainer means comprising a substantially flat sheet-like means defining a central hole for snugly engaging an associated punch and being of such thickness that it is adapted to flex in opposite directions while in .gripping engagement with an associated punch, said retainer means defining a first surface facing toward said second end portion and an opposite surface facing toward said first end portion, and a flat surface engaging said opposite surface of the retainer means, said retainer means extending radially inwardly of said fiat surface only a very small distance whereby said flat surface tends to prevent flexing of said retainer means in a direction to release the stripper apparatus from an associated punch.

2. Apparatus as defined in claim 1 wherein said retainer means includes an inner area defining a plurality of spaced portions the inner surfaces of which are spaced to provide said central hole.

3. Apparatus as defined in claim 2 wherein said spaced portions of said inner area comprise a plurality of inwardly extending portions which are angularly spaced from one another and which have a greater degree of flexibility and resiliency than the port-ions of the retainer means disposed outwardly thereof.

4. Apparatus as defined in claim 1 wherein said resilient means comprises a body formed of elastic material, each of said end portions having a recess formed therein for receiving one end portion of said body, said retainer means being disposed within the recess of said first end portion and being interposed between said body of elastic material and the associated end :portion.

5. Apparatus as defined in claim 1 wherein said resilient means comprises compression spring means, means for limiting movement of said end portions away from one another, said retainer means being clamped in operative position in contact wth said first end portion.

6. Apparatus as defined in claim 5 wherein said first end portion is provided with a cutaway portion adjacent said retainer means for permitting flexing of the inner portions of the retainer means when in gripping engagement with an associated punch.

7. Apparatus as defined in claim '1 wherein said one end References Cited by the Examiner portion ineludes a recess, said retainer means being dis- UNITED STATES PATENTS posed within said recess and including a plurality of spaced 5 42 2/ 4O 1 83 6 outwardly extending projections which are in engagement 2,22 1 19 t 13 2,712,262 7/1955 Knohl 8536 with the wall of said recess. 5 2 60 8 8. Apparatus as defined in claim 1 wherein said one end 1 ffg 2 7*115 portion is provided with a recess, said retainer means $102,508 9/ 9 3 85 36 being disposed within said recess, the outer periphery of 3211035 10/1965 Whistler et 83 139 said retainer means being substantially elliptical in configuration and engaging spaced portions of the wall of 10 WILLIAM DYER Primary Exammer' said recess. L. B. TAYLOR, Assistant Examiner.

Claims

1. PUNCH STRIPPER APPARATUS COMPRISING A FIRST RELATIVELY RIGID END PORTION AND A SECOND RELATIVELY RIGID END PORTION SPACED FROM SAID FIRST END PORTION, EACH OF SAID END PORTIONS HAVING A CENTRAL HOLE FORMED THERETHROUGH FOR RECEIVING A PORTION OF A PUNCH, RESILIENT MEANS INTERPOSED BETWEEN AND ENGAGING SAID FIRST AND SECOND END PORTIONS, SAID RESILIENT MEANS DEFINING A CENTRAL CLEARANCE AREA FOR RECEIVING A PUNCH, AND RETAINER MEANS ADJACENT SAID FIRST END PORTION FOR RETAINING THE STRIPPER APPARATUS ON A PUNCH, SAID RETAINER MEANS BEING MEANS OF A RELATIVELY RIGID RESILIENT MATERIAL, SAID RETAINER MEANS COMPRISING A SUBSTANTIALLY FLAT SHEET-LIKE MEANS DEFINING A CENTRAL HOLE FOR SNUGLY ENGAGING AN ASSOCIATED PUNCH AND BEING OF SUCH THICKNESS THAT IT IS ADAPTED TO FLEX IN OPPOSITE DIRECTIONS WHILE IN GRIPPING ENGAGEMENT WITH AN ASSOCIATED PUNCH, SAID RETAINER MEANS DEFINING A FIRST SURFACE FACING TOWARD SAID SECOND END PORTION AND AN OPPOSITE SURFACE FACING TOWARD SAID FIRST END PORTION, AND A FLAT SURFACE ENGAGING SAID OPPOSITE SURFACE OF THE RETAINER MEANS, SAID RETAINER MEANS EXTENDING RADIALLY INWARDLY OF SAID FLAT SURFACE ONLY A VERY SMALL DISTANCE WHEREBY SAID FLAT SURFACE TENDS TO PREVENT FLEXING OF SAID RETAINER MEANS IN A DIRECTION TO RELEASE THE STRIPPER APPARATUS FROM AN ASSOCIATED PUNCH.