PUNCH PRESS DIE HOLDER WITH HAND-OPERATED RETAINING CLAMP

FIELD OF THE INVENTION

This invention relates to the punch and die art and more particularly to an improved die holder for a punch press.

BACKGROUND OF THE INVENTION hi the punch and die art and particularly in the field of high-speed automated forming and punching equipment for punching and forming a workpiece, e.g., sheet metal and especially in the case of automated turret punch presses, the punch presses are operated by computer to rapidly perform a series of punching or forming operations sequentially. These punch presses which by themselves form no part of the present invention are typically provided with aligned upper and lower turrets that rotate and are indexed intermittently between punching operations. The turrets may hold as many as a dozen or more separate punches that are used in sequence for performing given punching or forming operations. hi prior punch press die holders, the die is simply placed into a bored opening within the die holder and held in place by means of bolts, screws, or similar fasteners. Consequently, the placement and removal of a die requires the use of hand tools and is therefore labor intensive and time consuming. Although methods have been proposed to facilitate more rapid removal of noncircular dies, i.e. those that are octagonal, rectangular, etc., these methods are not applicable to circular dies. Thus, there has been no way to manually remove or replace circular dies that are in wide scale commercial use, that is to say without the use of hand tools. In addition, the die must be inserted or removed from the side since the top of the die holder is obstructed by the upper turret. It has been calculated that in the course of a day, a typical punch press operator may

spend as much as two hours removing and replacing dies, and of course the press is out of production during this period.

In view of these and other shortcomings of the prior art, it is one object of the present invention to provide a way of reliably securing a circular punch press die within a die holder that allows removal and replacement of the die without the use of hand tools.

Another object of the invention is to provide a hand-operated retainer that is capable of enabling a circular holder die to be opened or closed manually with what can be referred to as a flick of the wrist and to make it possible for a die to be removed and replaced from the side of the die holder.

Another object is to provide a reliable hand-operated die retainer that will not accidentally release the die or allow it to slide upwardly out of its holder once locked in place manually.

Yet another object of the invention is to provide a manually operable die-retaining device that can be retrofitted into a variety of existing punch press tooling units including what is known as "thick turret" tooling as well as other tooling that employs circular dies.

Still another object is to provide a manually operable die holder that provides precision positioning, centering and angular orientation of each die, yet allows the die to be rapidly removed or replaced from the side of the die holder by means of simple hand movements.

These and other more detailed and specific objects of the present invention will be better understood by reference to the following Figs, and detailed description which illustrate by way of example but a few of the various forms of the invention within the scope of the appended claims.

BRIEF DESCRIPTION OF THE HGURES

Fig. 1 is a top perspective view of one preferred form of the invention as seen before a die is mounted therein;

Fig. 2 is a side elevational view partly in section along line 2-2 of Fig. 1;

Fig. 3 is a side elevational view of the clamp of Figs. 1 and 2;

Fig. 4 is a perspective view of the clamp with a die mounted in the die holder;

Fig. 5 is an enlarged top plan view of a swivel that is used as a part of the die holder;

Fig. 6 is a perspective view of the swivel shown in Fig. 5;

Fig. 7 is a perspective view of an upper portion of the clamp of Figs. 1-4 with the die clamp member removed;

Fig. 8 is a side elevational view taken on line 8-8 of Fig. 7; and

Fig. 9 is a diagrammatic partial plan view of the clamp fastener assembly on an enlarged scale;

Fig. 10 is a perspective view of another embodiment of the invention showing the die holder in a closed position and;

Fig. 11 is a perspective view of the die holder of Fig. 10 on an enlarged scale in an open position.

SUMMARY OF THE INVENTION

The invention provides a die holder assembly for a punch press that includes an annular die holder body with a circular rim which surrounds a die receptacle or socket within the die holder body. The receptacle is dimensioned to receive a punch press die, especially of any various circular dies now in wide scale commercial use. At the bottom of the receptacle is a die- supporting surface for limiting the downward movement of the die during operation. A moveable

clamp member is provided as a part of the die holder. The clamp member has a centrally directed circular clamping surface which is constructed to forcefully engage the die when the die is in place within the receptacle. A manually moveable fastener is operatively connected to the clamp member to hold the clamp member in a closed position so as to prevent movement of the die but is able to be moved by hand to an open position for releasing the clamp member so that it can be removed bodily or swung to one side to permit lateral removal of the die from the die holder. In a preferred form, the clamp member is an arcuate element which comprises a segment of the rim of the die holder that surrounds the die. The clamp member preferably comprises a segment of a circle having the same inside diameter as the outside of the die. The ends of the clamp member are each connected to an adjoining portion of the rim. A connection at one end of the clamp member comprises the manually operable fastener. The other connection comprises a pivot or an easily separated connection such as a hook and socket connection between the end of the clamp member and an adjacent portion of the rim. In one form, the clamp member is provided with a hook, e.g. at its left end, that is engaged in a complementary shaped socket provided in an adjacent fixed portion of the die holder. A preferred fastener comprises a manually movable cam member at one end of a locking handle connected between the opposite end of the clamp and the die holder for forcefully moving the clamp to a closed position for holding the die in place when the cam is moved manually to a locking position.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Refer now to the Figs., and particularly to Figs. 1-4 which show a punch press die holder assembly 10 having an annular die holder body 12 with a circular rim 14 surrounding a generally cylindrical die receptacle or die socket 16. The die holder 10 is mounted on the punch press (not

shown) in any suitable manner, e.g. using a base plate 13 of conventional well-known construction. The die holder 10 has a downwardly extending inner sleeve 11 of conventional construction that is journaled for rotation in the base plate 13. Sleeve 11 can be secured to the lower portion of receptacle 16 by fasteners such as cap screws 15 (Fig. 1). The receptacle 16 is dimensioned to receive the circular punch press die 18 (Fig. 4). At the bottom of the receptacle 16 of the die holder assembly 10 is a circular die-supporting surface 20 (Figs. 1 and 7) for limiting the downward movement of a die 18 when the die is mounted for operation within the receptacle 16 as shown in Fig. 4. Receptacle 16 has a centrally projecting locating pin 17 that fits into a slot 19 (Fig. 4) for holding the die 18 at the desired angular orientation. The die holder 12 has a rim 14 that is divided into two parts including a fixed portion 14a that is an integral part of the die holder 10, having a left end 14b and at the right end is provided a clamp hook 14c. The fixed rim 14 encircles approximately half of the die 18. The other half is encircled by a removable segment which comprises an arcuate clamp member 22. The clamp member 22 has a centrally directed preferably circular clamping surface 22a which is constructed to contact the die 18 when the die is in place and is equal in diameter to the outside diameter of the die. A manually operable fastener assembly is removably connected to the clamp member 22 to hold the clamp member 22 in place when in a locking position but is capable of being moved by hand to an open position for releasing the die from the die holder 10.

The clamp member 22 is in one form shown in Figs. 1-9, a removable segment of the riml4 of the die holder 10. In this embodiment, at the left end of the clamp member 22 is a connection comprising centrally directed hook 22b that is engaged in an outwardly opening socket 14d at one end of the rim segment 14a to provide a secure pivotal connection that is easily separated to permit bodily removal of the clamp member 22. At the right end 22c of the clamp

22 as seen in the Figures is the manually operable fastener assembly 24. The centrally projecting hook member 22b is dimensioned to fit within the outwardly facing socket 14d in the rim segment 14a. As shown in Fig. 8, the socket 14d has a pair of generally upright sidewalls 14e and 14f. The wall 14f, which is closest to the end 14b, is not vertical but is tilted with its lower end closer to the clamp member 22. It can be inclined typically at an angle of about 2° to about 10° from a vertical line at 30 shown in Fig. 8. The mating wall of the hook 22b is similarly inclined to cooperate with the inclined wall 14f of the socket for preventing the clamp from sliding upwardly or moving when locked in place by a clamp fastener assembly 24 (Figs. 3, 4 and 9) which will now be described while also allowing clamp 22 to be completely removed.

The clamp fastener assembly 24 includes a tension element, e.g. a cap screw 32, or other elongated fastener which extends through a slot 15a (Fig. 7) in the die holder, then through a bored opening 22d in the clamp 22, next through a washer 34 and a swivel 36. The swivel 36 includes a vertical bore 36a (Figs. 5 and 6) for two vertical pivot pins 40 and 42 and a horizontal threaded bore 36b for the screw 32. The open top of slot 15a and connection with the clamp hook 14c enable the clamp 22 to be removed from the side of the die holder 10 to permit side replacement of dies since the die receptacle is normally inaccessible from the top. The screw 32 and swivel 36 are secured to a cam member 38 by the vertically aligned upper and lower pivot pins 40 and 42. In this way, the cam 38 is mounted for pivotal movement on the pins 40 and 42.

During use, the cam 38 can be positioned manually by an extension comprising an integral locking handle 38a which, as shown in Fig. 1, is of arcuate shape to conform to the outer surface of the clamp 22 when in a closed position (Fig. 1). The right end of cam member 38 is bifurcated to provide similarly contoured upper and lower cam elements 38b and 38c (Figs. 1 and 2).

The axis 38d of the cam lobe, i.e. the high point 39 of the cam 38 (Fig. 9), is positioned to pass somewhat beyond the center of screw 32 to an over center position when the cam 38 is in its closed position thereby locking the clamp member 22 in place and causing it to apply pressure against the adjacent face of the die 18.

To assemble the clamp fastener assembly 24, the screw 32 which has an adjustment nut 46 near the head is passed through the bore 22d of the clamp 22, is then threaded into the swivel 36 and is preferably bonded therein, e.g. with Loctite®. The swivel 36 is then placed between the bifurcated ends 38b, 38c of the cam and pins 40 and 42 are inserted. The screw 32 is placed in slot 15a and the adjustment nut 46 is then tightened against the bearing surface 15c of the clamp hook 14c to be almost tight when the locking handle 38a is in and "open" dotted line position of Figs. 3 and 4. Before the clamp 22 is mounted on the die holder 10, the die 18 is placed in the receptacle 16 from the side. The clamp 22 is then placed over the die 18 and the locking handle 38a is moved manually to the closed position (from left to right as seen in Fig. 1 of Figs. 1, 2 and 4) thereby drawing the right end of the clamp 22 toward the right in the Figs, as its left end pivots about the hook and socket connection so that the inner surface 22a of the clamp 22 provides firm pressure against the abutting outer cylindrical outer wall of the die 18 as the cam 38 locks the clamp 22 in place, thereby securely retaining the die in place within the die holder 10.

Refer now to Figs. 10 and 11 wherein the same numerals refer to corresponding parts already described. These Figures show a modified form of the invention which includes a pivoted handle extension and an additional handle locking feature, hi this embodiment, the curved locking handle 38a is provided with a longitudinally extending centrally located slot 38b to accommodate a curved handle extension 100 that is held in place at its proximal end, at the

left in this case, by means of a vertical pivot pin 102 that is able to slide longitudinally with respect to handle 38a, i.e. horizontally through upper and lower vertically aligned slots 104 and 106 in the handle 38a. A ball plunger 108 can be provided in extension 100 to act as a detent for holding the handle extension 100 in its inactive or closed position (Fig. 10) by yieldably biasing balls upwardly and downwardly into sockets, only one of which is shown at 110 in the handle 38a. It can be seen that the die holder 10 is provided with a slot 112 that opens upwardly and toward the free end of clamp 22 to accommodate the lower end of the pin 102 for securely holding the handle 38a in a closed position as shown in Fig. 10 when the handle extension 100 is shifted toward the free end of handle 38a. Handle 38a is then pivoted inwardly to the closed position of Fig. 10.

At the left end of the handle 38a is provided a vertical pivot pin 41 that extends through an enlarged head 116 of an eyebolt 118. Threaded on the free end of the eyebolt 118 is a contoured nut 120 for holding the clamp member 22 in a closed die locking position when eyebolt 118 is placed within the slot 15a of the clamp hook 14c. Nut 120 should be turned to adjust the clamping force of handle 38a to about 25 lbs. Located approximately below the center of the clamp 22 is a finger slot 122 that is cut into the body of the die holder. As can be seen, the finger slot 122 opens upwardly as well as horizontally toward the position taken by the operator for enabling the operator's finger to be inserted beneath the die 18 when the die is to be removed. Connected by means of a clamp adjustment screw 129 to the left end of rim 14 is a moveable clamp adjustment base 131 which allows the clamp 22 to be moved to the left or right, i.e. toward or away from the left end of the rim 14 by turning the clamp adjustment screw 129. It will also be noted that the clamp member 22 is in this case provided with a clamp link 124 which

is connected to the clamp 22 by means of a pivot pin 126 and to the clamp adjustment base 131 by means of a second pivot pin 128.

When a die 18 is to be to removed, the die clamp arm extension 100 is swung outwardly to a releasing position (Fig. 11) about the pivot pin 102 and by grasping the extension 100, the pin 102 is shifted toward the right in the Figures out of the retaining slot 112 thereby releasing the locking handle 38a which can then be pivoted outwardly (counterclockwise) as shown in Fig. 11 about pivot pin 41 thereby releasing tension on the eyebolt 118 and allowing the bolt head 120 to be released from the clamp hook 14c. It will be seen that an opening 130 which extends through the free end of the clamp 22 to accommodate the eyebolt 114 is elongated vertically for enabling the bolt 118 to pivot upwardly out of slot 15a as the locking handle 38a is pivoted downwardly as seen in Fig. 11 thereby freeing the clamp 22 so that it can be swung outwardly to an open position as shown in Fig. 11 so as to enable the die to be slid manually by the operator out of the die holder (toward the left in Fig. 11) without moving it either up or down. This operation can be assisted by placing one finger in the finger slot 122 below the die 18 to allow a slight lifting of the die to release it so that it does not stick to the bottom due to oil suction. In this way the die can be quickly removed by sliding it horizontally to one side even though the upper turret of the punch press (not shown) is closely spaced above its upper surface. The link 124 by allowing more extended opening facilitates removal of the clamp 22 and provides a wider opening for the removal or replacement of the die.

To close the clamp 22 after the die 18 has been inserted, the clamp is moved to the position shown in Fig. 10, the eyebolt and nut 120 are then lowered by raising the free end of the clamp arm extension 100 so as to place the eyebolt 118 in the slot 15a. The locking handle 38a is then pushed inwardly to the closed position shown in Fig. 10 so that the camming action of the

cam lobe 38b at its right end as already described above in connection with Fig. 9, draws the eyebolt 118 toward clamp 22, i.e. toward the left in the Figures thereby causing the clamping nut 120 to be forced tightly against the clamp hook 14c. The clamp arm extension 100 is slid to the right so that it can then be then pivoted inwardly to the closed position shown in Fig. 10. The extension 100 and pin 102 are then shifted to the left into the retaining slot 112 thereby securely locking the clamp arm 22 in the closed position.

The invention is rugged in construction, reliable in operation, and will securely hold circular dies 18 in the die holder but yet can be opened quickly with a flick of the wrist using no tools by manually pivoting the free end of the locking handle 38a outwardly to remove tension on screw 32 or bolt 118 thereby relieving the compressive force applied by the clamp member 22 against the adjoining wall of the die 18. When the clamp 22 is swung away from body 12 of the die holder, the die 18 can be easily withdrawn and replaced from one side whenever required. The handle extension 100 makes possible two important results at the same time; it acts as a lock when the pin 102 enters the recess 112 and the ease of opening and closing the die holder is substantially improved since the extension 100 is provided a greater moment arm. It was also found that the finger hole enables the die to be readily grasped for easy removal by the operator.

The directions; up, down, horizontal, left, right, etc. herein are used in a relative sense without limiting the spatial orientation of the die holder.

Many variations of the present invention within the scope of the appended claims will be apparent to those skilled in the art once the principles described herein are understood.