US2293264A

US2293264A - Punch and die set holder

Info

Publication number: US2293264A
Application number: US394971A
Authority: US
Inventors: Freeland H Leslie
Original assignee: Individual
Current assignee: Individual
Priority date: 1941-05-24
Filing date: 1941-05-24
Publication date: 1942-08-18
Anticipated expiration: 1959-08-18

Description

18, 1942. F. H. LESLIE 2,293,264

' BUNCH AND DIE SET HOLDER Filed May 24. 1941 Fig.1.

. 2a. 20 14 22 15 m1 A4 IIHTIIIII 10 13 I mm I I A MHHIMWIIII" I, WW I "WWII" INVENTOR.

Patented Aug. 18, 1942 UNITED STATES PATENT OFFICE PUNCH AND DIE SET HOLDER Freeland H. Leslie, Chicago, Ill.

Application May 24, 1941, Serial No. 394,971

9 Claims.

This inventionrelates to punch and die set holders, which frequently are referred to as subpresses. This is a continuation in part of applicants co-pending application, Serial No. 276,- 247, filed May 27, 1939.

The primary object of this invention is to provide a punch and die set holder which does not become inaccurate due to use. In the conventional punch press today, a leader pin die set comprising pins mounted on a punch plate holder and penetrating the die shoe so as to maintain alignment between a punch and a die mounted in the leader-pin die set is subjected to all the distortional strains caused by the punch entering the workpiece because the die shoe of the leaderpin die set is rigidly fastened to the bolster plate of the punch press while the punch plate holder of the leader-pin die set is rigidly fastened to the bottom of the ram. Misaligning forces produced by the punch entering the workpiece cause Wear of the pins of the punch and die set, as also wear of the slides and ways which guide the stroke of the ram. g

The principal feature of this invention is the positioning of two substantially inflexible members in side by side relationship and fastened together at one end, together with means for permitting the flexing of the free end ofone of the members toward the free end of the other member so that the space between the two free ends may be defined as a punching zone anda punch and a die may be mounted in opposed relationship on the free ends of the two substantially parallel members. 'By establishing the point of flexing at a substantial distance outside of the punching zone, a punch and die set holder of great accuracy is provided. Upon a penetration of a punch into the die of one-eighth of an inch, where the pivotal point is from twelve to fifteen inches away from the punching zone, an accuracy of 710000 of an inch is obtained.

Another objectof this invention is to assure pivoting or flexing of the movable leaf at a very limited point. Where flexing is permitted throughthe entire length of one'of the members, accurate alignment of the punch and the die is not obtained with the result that a tearing action is obtained in the cutting operation.

Another object of this invention is to provide an independent flexing means at the point of flexing in order to avoid crystallization of the steel of one of the parallel holding members during use.

A further object of this invention is to provide a new and improved means for mounting a con- 5 ventional punch holder in one of the parallel members constituting a subpress. In applicants particular type of subpress, the spacing between the free ends of the leaves can be varied only through a comparatively limited range. Inasmuch as a conventional punch holder has a two or three inch lug extending upwardly, it is frequently difficult to mount such a punch holder in applicants type of punch and die set. Toward overcoming this difliculty, one of the features of this invention is the slotting back of the punch plate holder so as to permit the insertion of the lug on a punch holder from the side together with the provision of means for holding the lug and the punch plate in the punch plate holder.

These and such other objects as may hereinafter appear'are attained in the embodiments of the invention described belowand set forth in the drawing, comprising one sheet, wherein:

' Figure 1 is a side view in elevation of one form of this invention; v

Figure 2 is a perspective view of a second form of this invention;

Figure 3 is a perspective View of the third form of this invention; and

Figures 4 and 5 are schematic views to illustrate certain principles.

Continuing to refer to the drawing and particularly to Figure 1, It! identifies a base which depending upon the loading capacity of the subpress is substantially rigid. At one end is a spacer member 12 upon which is mounted a leaf [4 which depending upon the load capacity may be flexed at its free end with respect to the base 10. The leaf I4 is fastened to the spacer member l2 and to the base In by any suitable means such as bolts It. The space indicated by the lead line from the numeral I8 identifies the punching zone and it is contemplated as shown in other figures that a punch holder and die shoe will be mounted in the space between the two free ends of the members IQ and M in the punching zone I8.

The leaf member It carries a reinforcing member 20 which extends from a point above the punching zone [8 to a point 22. This point 22 identifies a portion of the leaf I4 which may be referred to as the flexing point orflexing zone of the leaf I l. The reinforcing member 26 is rigidly fastened throughout its length to the leaf I4 and has the effect of limiting flexing of the leaf I4 due to a force applied as indicated by the arrow 21 to this flexing zone.

As discussed in theco-pending application, this reinforcement of the leaf l4 so as to limit the flexing zone to a point close to that place where the leaf is fastened to the base I8 is of the utmost important where off-center loading occurs. Referring to Figure 4, the cam H8 applies force at the point I28 and while this force may move laterally, that is, lengthwise of the leaf I84 for practical purposes, the force is applied at right angles to the punching zone. In this figure, a punch I24 together with a die shoe I26 is mounted in front of a vertical line passing through the point I28 with the result that where a leaf I34 is of uniform strength throughout its length, it will then tend to assume the configuration of the curved line I85 and thereby cause misalignment of the punch and the die.

On the other hand, referring to Figure 5, where the punch I34 and the die I38 are mounted behind a vertical line passing through the point I28, a leaf which is not reinforced tends to take the form indicated by the line I01, and again causes misalignment of the punch and the die. It will be understood that the lines I and I01 are exaggerated. The effect of a subpress so constructed is to cause the punch to tear the workpiece. Returning to Figure l, the reinforcing member 28 completely eliminates this defect. This flexing zone 22 becomes in reality a pivotal point so that when the punch and the die are once aligned the punch moves through an arc regardless of whether it is passed through a workpiece into the die.

An improved embodiment of this invention is illustrated in Figure 2 wherein the leaf member 26, which itself constitutes the punch plate holder, has an offset portion 28. 38 with punch 32 is mounted on the leaf 28 while a die 34 is disposed on the base member I I) by any suitable means. The purpose of the offset portion 28 is to make it possible to establish a common plane for the flexing point 36 and the points at which the punch 32 enters the die 34. Reverting for the moment to Figure 1, it will be understood that if a conventional punch and a die are positioned in the punching zone I8, the point at which the punch enters the die will be below the flexing zone 22 with the result that the plane defining the points in which the punch enters the die does not contain a radius of a circle having the pivotal point 22 as the center. The result is that the punch and the die either must be tilted or misaligning movement will occur. By the construction shown in Figure 2, however, the plane in which the punch enters the die includes the pivotal point 28 or does so approximately with the important result that the side walls of the punch are moving substantially parallel with the side walls of the die. The stroke is very short in this type of press and advancing the punch into the die by one-eighth of an inch causes no appreciable wear between the two. Where the pivotal point 22 is twelve to fifteen inches from the punching zone I8, the departure of the punch from the vertical in a one-quarter inch stroke is less than $4 of an inch.

The embodiment shown in Figure 2 further departs from the embodiment shown in Figure 1 by substituting for the leaf I4 and reinforcing member 20 a single heavy substantially inflexible member 26 which, however, is weakened at the point 38. This constitutes an improvement over the first form from the standpoint of construction. Moreover, the upper leaf 26 has a better appearance than the reinforced leaf l4.

A punch holder In Figure 3, a very important feature of ap plicants subpress is disclosed. It will, of course, be understood that the primary object of this type of subpress is to handle shallow drawing and punching, the punches being either straight or of the sheared type. Because of the need for establishing a very rigid relationship between the base such as I8 and the punch holder and of the leaf, such as 38, in the punching zone I3, it is necessary to limit the degree of flexing that may take place in the flexing or pivotal zone 48. Consequently, the free end of the leaf 38 cannot be spread a very great distance from its normal position with respect to the base. It is quite difficult to mount a punch holder on the leaf 38 because the average punch holder has a heavy lug extending upwardly for from two to three inches, a construction developed in the punch press art over a long period of time. In order to avoid spreading the leaf 38 excessively, applicant provides a slot 42 out back from the front of the punch plate holder, which may either be the free end of the leaf 38 or a separate plate of metal rigidly fastened to the leaf 38. The slot 42 extends to a point containing a vertical line passing through the punching zone I8. A lug 44 on the punch holder may be inserted from the front of the press into the slot 42 and held tightly thereto by a locking member 46 by any suitable means, such as bolts 48 and 58.

It will be appreciated that the need for this slot 42 is dependent upon the mounting of the punch plate holder 52 on the leaf 38 and upon the leafs 38 mounting on the base I0. It would be possible to remove the leaf from the base and mount the punch holder therein or the punch plate holder 52 from the leaf 38, as would be possible in Figure 3 where the punch plate holder 52 is held to the leaf 38 by removable means such as bolts 54. As indicated, however, it is desirable to maintain the leaf, the punch plate holder and the base in a somewhat permanent relationship and consequently the punch plate holder is frequently integral with the leaf by being a part of the original piece of metal or is welded thereto.

A further feature of this invention is illustrated in Figure 3 and relates to the piece of metal identified by the numeral 58. Unlike the other two embodiments of the invention, the leaf 38 is not fastened to the base member ID and consequently it may be of whatever strength and of whatever material may be necessary to establish rigidity. Relative movement between the leaf 38 and the base I0 together with the normal relationship therebetween is established by the plate 58 and all flexing occurs in the flexing zone 40. The adoption of the plate 58 was necessitated by the use of this subpress in conventional power presses. Leaves, such as I4 and 26, in Figures 1 and 2, having the requisite strength were generally of a type of steel which became crystallized and brittle due to bending at the pivotal or flexing point. Returning to Figure 3, the plate 58 is made of spring steel which is designed specifically to flex without crystallization. Moreover, the comparatively short length of flexing point permits the comparatively thin plate 58 to resist any distortional forces because these forces are always acting substantially horizontally and the plate 58 will act as a column in resisting such forces.

The foregoing sets forth the features of the new and improved punch and die set holder. Under normal conditions is is contemplated that closed is comparatively light.

the leaf having the flexing portion will be for the most part permanently mounted With respect to the base and that the punch and die set will be used in much the same way as the leader pin die set in common use today. In many instances a lead pin die set carries a particular punch and die which will be used quite regularly and consequently the punch and the die will never take out of the leader pin die set. The leader pin die set is removed from the punch press between operations.

It will be noted that the punch and die set dis- The distortional forces acting between the upper leaf and the base are comparatively few. It is not contemplated that the upper leaf be rigidly fastened to the ram of the press, but that a sliding relationship be established therebetween. In consequence of this, this type of punch and die set holder may be considerably lighter than a leader pin die set of equal capacity.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

l. A subpress to be used in association with a punch press comprising, in combination, a substantially inflexible member having aflixed to one end thereof a complementary substantially inflexible member, and said latter member being offset so that a substantial space is created between the free ends of said members whereby to receive a punch plate and die shoe, and said second substantially inflexible member having a weakened portion adjacent the point of joinder of the two members.

2. A subpress to be used in association with a punch press comprising, in combination, a substantially inflexible member having affixed to one end thereof a complementary substantially inflexible member, said latter member being offset so that a substantial space is created between the free ends of said members, whereby to receive a punch plate and a die shoe, said second substantially inflexible member having a transverse weakened portion capable of flexing when pressure is applied to the free end of the member, said transverse flexing portion being in approximate alignment with the top of any die mounted on the die shoe.

3. A subpress comprising a substantially inflexible member, a second substantially inflexible member held at one end in substantially parallel relationship to one of the first members so as to form a punching zone between the free ends of the two members, and means for permitting movement of the free ends of the two inflexible members relatively to each other, said means comprising a flexible portion in the second substantially inflexible member disposed approximately in a plane including the top of a die that may be positioned in said punching zone.

4. A subpress comprising a base, a punching zone above a portion of said base, a flexible member mounted on said base outside the punching zone, a substantially inflexible member having one end attached to said flexible member and having its free end extending into the punching zone, means on the base adjacent the punching zone for supporting a die shoe, and means on the free end of the substantially inflexible mern-- ber for holding the punch holder.

5. A subpress comprising a base member, a punching zone above one end of said base member, means at said end for supporting a die, means at the other end of said base member for supporting a second member at approximately the level of the top of a die mounted on said base member, a flexible member mounted on said last named supporting means, a substantially inflexible member having one end attached to said flexible member and having its free end extending into the punching zone, and means on the free end of said substantially inflexible member for holding a punch holder.

6. In that type of punch and die set holder comprising two substantially parallel members having means at a common end of the parallel members fOr maintaining such parallel relationship and having a punching zone between the free ends thereof, a slot cut into one of the two substantially parallel members to permit the insertion of a lug on a punch holder, and means for locking such a lug in said slot.

7. In that type of punch and die set holder which comprises two substantially parallel members having means at a common end for maintaining such parallel relationship therebetween and having a punching zone between the free ends thereof, a slot cut into the end of one of the two substantially parallel members so as to permit endwise insertion of the lug of a punch holder, and means for locking said lug in said slot.

8. A subpress comprising two substantially parallel spaced arms held in assembled relationship at a common end thereof so as to form a punching zone between the free ends, and a weakened portion in one of the spaced arms disposed between that end of said arm which forms the punching zone and the other end of said arm held in assembled relationship to the other arm, whereby the free end of said arm may be moved about the weakened portion toward the other arm.

9. A sub-press comprising a pair of substantially inflexible members assembled in spaced relationship to provide a punching zone therebetween for receiving on one of said member a plurality of dies having their cutting surfaces coincident with a plane extending lengthwise of the substantially inflexibl members, and means joining the said substantially inflexible members for holding the same in said assembled relationship and for permitting movement of the members toward and away from each other in the punching zone, said last named means being positioned approximately in said plane.

FREELAND H. LESLIE.