US2554916A

US2554916A - Release cam

Info

Publication number: US2554916A
Application number: US141924A
Authority: US
Inventors: Miller Charles Willard
Original assignee: Individual
Current assignee: Individual
Priority date: 1950-02-02
Filing date: 1950-02-02
Publication date: 1951-05-29
Anticipated expiration: 1968-05-29

Description

May 29, 1951 c. w. MILLER RELEASE can Filed'Feb'; 2-; 1950 NVENT 6%az1es' M a?! ORNE 3 Patented May 29, 1951 UNITE Appiication February 2, 1950, Serial No. 141,924

This invention relates to camming mechanisms and particularly to a camming arrangement designedto effect lateral movement of a member when a second member, carrying a cam, is'moved toward or from the first member.

The subject matter of the present invention has particular utility in connection with the fabricationof metal structures in punch presses.

It is often desirable, in the operation of punch presses, to perform forming, piercing and trimming operations on metal by forcing a punch into a die to'thereby shape metal placed therebetween. It is'known in the prior art to effect transverse movement of the die member during some portion or-portionsof the punch stroke to further form or shape the product or to trim the edges thereof; In such prior art practices the die is usually provided with cam surfaces engageable with fixed cams on a die support. After the punch has entered the die and performed a preliminary shaping operation, the die moves downwardly with the punch and the interengaging cams on the die and die support cause the dies to move laterally of the punch to effect the desired operation. In such prior art struc tures' the die always moves through a predetermined cycle of lateral working movements on.

the downstroke and repeats those cycles, in

reverse, on the upstroke of the punch. The lat.-,

ter movements are non-working or idling cycles.

The present invention provides a camming,

mechanism to effect lateral cycles of movement of the dies during the downstroke of the punch but permit the dies to remain stationary during the upstroke or to return to starting position at any position of the punch.

In general, the invention comprises a pivoted cam carried by either the punch or the die and spring-held in position to engage a cam surface on the other member to effect lateral movements of one of the members during one stroke and permitting the cam to swing outwardly on the otherstroke to pass the cam surface without actuating the member upon which the cam surface is formed. When employed in connection with punch press operations, the pivoted cam element may be mounted either on the die slides or on the punch head. A special advantage of the present arrangement resides in the fact that the same cam elements may be reused for different product designs, whereas the usual prior art camming mechanism must be scrapped upon changes in product design and are not adaptable to a variety of uses.

It is, therefore; an object of this invention to claims. (Cl. 164-47 provide a cammin mechanism for causing lat eral movement. of a member when the cam;

ming mechanism ismoved in onedirection while ltis. a still further objectof this invention to provide. a camming mechanism of the type. described that may be adapted to produce various combinations of. movementswithout modification and to eliminate the. necessity of scrapping the cam structures for every change in the desired cycles .of operation. 7

it is a still further object of this invention to provide a. camming mechanism to effect lateral movement of a member when another mem oer, carrying the camming mechanism, is caused to more inv one direction and wherein the camming mechanismis. adaptable to other members havin strokes of different lengths.

Other objects, and advantages will become apparent to those skilled in the art as the descriptionv proceeds; in connection with the accompanying drawings, wherein: V r Fig. 1 is a front elevational View of a schematically shown punch press with a mechanism of the present invention attached thereto.

Fig. 2 is a side elevational view of the camming mechanism and a fragmentary portion of a driven member. Y

Figs. 3 and 4 show the camming mechanism iii-different relative positions assumed during a cycle of operation, certain parts being omitted for clarity of illustration. Fig. 5 is a front elevational view of the pivoted cam structure of Fig. 2,:ongitting the driven memher, when viewed from the right thereof. 4

Fig. 6 is a view similar to Fig. 3 but illustrating a modified ifOlm of cam element. i

a Fig. Tis a front elevational view of apparatus embodying the present invention but adaptedto operate with a different apparatus from that illustrated in the previous figures. A Fig. 1- illustrates a representation of a punch press which inciudes a suitable supporting frame it anda die supporting table l2. The frame it and table I? support an; upwardly extending frame It to which vertical guides or tracks J5 are. attached. A plunger is carries a head, 26 h vin por o s g d in the sui e a s Qr. t c

- ifitand the plunger it is'actuated by mechanisms not shown to move upwardly and downwardly to move the head 28 toward and from the table l2. The table i2 fixedly supports a transverse guide 22 in which a slide 24 is guided for lateral movement only across the top of table I2. The slide 24 may be provided with a vertical opening 28 therethrough in which a die 28 is mounted for vertical sliding movement relative to the slide 24. Suitable means (not shown) are provided for resisting downward movement of the die 28 and offering sufiicient resistance thereto to permit a preliminary forming operation on sheets of metal placed over the die. The forming of the metal takes place by forcing a relatively flat sheet into a cavity 30 of the die.

The head 28 carries a downwardly extended punch member 32 which in turn carries a punch head 34 mounted thereon for limited lateral movement relative to the punch 32. A sheet of metal to be formed is placed across the die 28 overlying the cavity 38 therein. As the plunger 18 is lowered, the punch head 34 engages the metal and is of such dimensions as to readily enter the cavity 30, forcing the metal therein and causing it to assume the shape of the cavity 30. As stated previously, means are provided to prevent downward movement of the die 28 until the metal has been forced into the cavity 38. When the metal has been forced completely into the cavity 80, continued downward movement of the head 28 will cause the die 28 to move downwardly therewith in the opening 25 in slide 24 while the slide 24 remains vertically stationary. During this continuing downward movement inter-engaging cam mechanisms cause the slide 24 to move transversely of the table I2 and since the punch head 34 is within the cavity 3!], it will, of course, move laterally with the slide 24 while moving downwardly in the opening 28-. The relative positions and dimensions of the parts are such that at that time the joint between the punch head 34 and the punch 32 is substantially in the plane of the top surface of the die 28. During lateral sliding movements of the slide 24, the lowermost edge of the punch 32 will cooperate with the upper surface of the die 28 to shear oif the upstanding edges of the sheet material. The lateral shearing operations may be performed by elements shaped to produce other shapes than straight lines, all as is shown in the prior art. The present invention is directed to a camming mechanism that may be employed for causing lateral movements of the slide 24 on the downward stroke of the head 28.

As shown in Fig. 1, the slide 24 is provided with a laterally projecting portion 35 having a cam surface 38 formed thereon. A camming mechanism indicated generally at 48 is fixedly carried by the head 28 and includes a cam element 52 engageable with the cam surface 38 to force the slide 24 to the right as the head 28 descends.

Ordinarily, a spring, not shown, is provided to return the slide 24 to the position of Figs. 1 and 2. However, to insure against damaging the apparatus in the event of failure of such a spring, a safety cam 3f, attached to the head 28, is arranged to engage a cam surface 33 on the slide 24 after the slide has been moved to the position of Fig. 3 to thereby insure that continued downward movement of the head 20 will return the slide 24 to the full-line position of Fig. 4 before commencement of a new cycle of operation.

Referring now particularly to Figs. 2 and 5, the cam mechanism 48 comprise a base block or plate 42 that may be rigidly attached, by weldhaving aligned openings 46 therethrough. A

pivot pin 48 is mounted in the openings 46 and may be held in fixed position therein by means such as a set screw 50 in one or both of the brackets 44. An elongated cam element 52 is journalled on the pivot pin 48 between the brackets 44 and is provided with an end cam surface 54 and a notch 58 in it upper edge. A.

driver or stop means 58 is fixedly attached to the base block 42 and extends downwardly in position to engage, with intimate surface contact, a surface of the notch 58 when the parts are in the relative positions shown in Figs. 2 and 3.. A pin 68 and a screw 62 on the cam element and base block, respectively, constitute anchors for the opposite ends of a tension spring 84. As will be readily apparent, the tension spring 54 urges the cam element 52 to turn about the pivot pin 48 in a counter-clockwise direction as seen in Fig. 2 and will normally hold the cam element with its notch surface in abutting engagement with the bottom surface of the stop means or driver 58. When the parts are in the positions shown in Figs. 2 and 3, with the cam element in abutment with the stop means 58, the cam surface 54 of the cam element 52 is parallel to the cam surface 38 on the slide 24 and the surface 54 is directly above the cam surface 38 in the retracted or uppermost position of the head 28 and the normal or central position of the slide 24.

The lowermost corner of the cam element 52 is cut away, as at 65, and the pivot pin 48 passes through the cam element 52 on an axis displaced downwardly from the central longitudinal axis of the cam element.

By virtue of the cut-away portion 55 and the lateral displacement of the axis of pin 48, it will be readily apparent that the center of pressure of the surface 54 is eccentric to the end of the cam element 52, and a line such as indicated at A in Fig. 2, extending from the center of pressure of the surface 54 to the axis of the pin 48 is not perpendicular to the surface 54 but extends therefrom at an acute angle, measured on the side of the line A opposite the side on which the stop means 58 and the notch 58 are located. By this arrangement it will be apparent that the reaction pressure on the cam element 52 during its slide-driving cycles will act along line B, normal to the surface 54 at the center of pressure, and introduce a moment tending to rotate the cam element counter-clockwise about the pivot pin 48, thus insurin that element 52 is held against the said stop 58.

Fig. 2 illustrates the relative positions of the cam mechanism and the slide at approximately the time when the cam element 52 engages the surface 38. At this time the cam mechanism is moving downwardly and it will be obvious that such downward movement, acting through the

surfaces

54 and 38, will cause the slide 24 to move to the right. Continued downward movement of the cam mechanism will cause the parts to move to the relative positions shown in Fig. 3 wherein the surface 54 has passed almost completely oil the lowermost edge of the surface 38, forcing the slide 24 a substantial distance to the right. Continued downward movement of the head 20 and cam element 52 will cause the tip 10 of the element 52 to pass completely ofi the surface 38 and ride along the vertical surface 72 of the slide 2 3. The tip 10 of the element 52 is preferably slightly rounded, as shown, to facilitate smooth passage over the edge of the surface 38. During movement of the tip 10 over the surface 72, no motion is imparted to the slide 24 by that particular cam element. During this'time, however, the slide 2d may be moved to the left by any suitable means, such as a spring or another cam mechanism similar to that just described but acting upon the opposite side of the slide. Fig. l illustrates the fact that the slide 2 may move to the left from the dotted line position to the full line position, or farther to the left, with no substantial resistance from the cam element 52. During such return movement of the slide 24, the cam element 52 may pivot about the pivot pin 28 in a clockwise direction against only the action of spring 6d and the notch 5% will move away from the lowermost face of the stop means 58, all as clearly illustrated in Fig. 4. The return movement of the slide 2% may be effected when the plunger i8 is at its lowermost position or during continued downward movement of the said plunger and the head Mi from the position of Fig. 3. Thus, a complete cycle of operation of the slide 24 may be accomplished during the downward stroke of the plunger and no movement will be imparted to the slide on the upward or return stroke of the plunger and head 28. During the upward or return stroke, the cam element 52 will freely swing to the left to clear anyobstacles or obstructions in its path and the spring 64 will return the element 52 to the position of Fig. 1 before commencement of the next following downward stroke.

Preferably the lowermost end of the stop means 58 is provided with a flat surface substantially normal to the direction of movementof the plunger It and engages a mating fiat surface defining an edge of the notch 56.

Return movements of the slide 2a to the full line position of Fig. 4 and further movement therebeyond may, as stated previously, be accomplished by additional camming mechanisms 69 fixed to the head 2B, but such additional mechanisms will necessarily be displaced from the position of the mechanism shown in Fig. 1 in a direction downwardly or upwardly therefrom so that different camming mechanisms will engage the slide is in successive intervals of the downward stroke. Clearly, additional camming mechanisms may act on the slide 24 to cause movements in a direction transverse to that shown in Figs. 2 to 4. Movements in directions at right angles to each other may be accomplished simultaneously, if desired.

It will be readily apparent that instead of supporting the camming mechanism 40 on the plunger head 20 it could, as effectively, be supported on the slide 24 and the head 20 could be provided with a suitable cam surface, corresponding to the surface 38, and the operations described above would result since they depend merely upon relative movement of the head 20 and the slide 24.

In addition to the modification suggested in the paragraph above, the parts may be so arranged that the slide 24 is caused to move vertically with the die member 28, in which case the

surfaces

38 and 33 would face downwardly and the camming mechanism 40 would be fixed to the table l2 in an inverted position. Thus relative movement between the slide 24 and the table l2, in a downward direction, would result in the same transverse movement of the slide 24;

Fig. 6 illustrates a modified form of cam element 52' wherein the cam surface engaging means comprises a roller 14 journalled to the end of the element 52 on an axis parallel to the axis of pivot pin 48. The point of contact between the roller 74 and the surface 38 is displaced laterally of the element 52 in the same manner and for the same purpose as described in connection with the lateral displacement of the center of pressure of the surface 54 of the Fig. 2 embodiment. A line A extending from the axis of the pivot pin 48 to the point of contact betweenthe roller 7A and the surface 38 extends from the said surface at an acute angle measured on the side of the line opposite the stop means 58. In the same manner as described in connection with Fig. 2, the reaction pressure exerted by the surface 38 on the element 52 will act along the line indicated at B to hold the element 52 firmly against the stop means 558 during all slide-actuating cycles.

The camming mechanism herein described may obviously be employed when producing a diverse variety of shapes involving the use of different punch and die members without alteration of the camming mechanism structure. At most, only repositioning thereof will be necessary. Upon a change in the design of the article to be produced, the present camming mechanism need not be scrapped, as is the case with known camming structures of the prior art. If a different shape of cam element 52 is required, it is only necessary to loosen set screws 58 and remove pivot pin 88, whereupon a differently shaped cam element may be inserted.

In the modification shown in Fig. 7, all parts identical to those of the previously described embodiments are identified by the same reference numerals. In this modification, however, a different type of die is used to perform a somewhat different operation than that described above. A support MB is mounted upon the table 52 and provided with a shoulder I92 defining a relatively sharp edge at its exterior periphery and an upstanding positioning member Hit. The positioning member Hi l is arranged to support and position a work piece it thereon with a scrap edge portion H38 extending outwardly over the edge I02. The work piece Hi5 will have been formed by a previous operation on another machine. One side of the member file-i515 is provided with a cut-out i it of such contour as to present the desired outline to the outer periphery of the portion m l. Suitable guiding means H2 are fixed to the table l2 and guide a punch carrier li t for rectilinear movement toward and from the support mil. The punch carrier I It carries a laterally extending punch i H3 of a size and shape complementary to the cut-out Ill) and is also provided with inclined cam surfaces H8 and i221. A camming mechanism 6'3, identical to that previously described, is mounted on a block E22 fixed to the head 28 in such position that it engages the cam surface M8 on the carrier M4 to force the carrier lid to the left as seen in Fig. 7 upon downward movement of the head 26 to thereby cause the punch H6 to perforate or out the work piece it to a shape determined by the contour of the punch HS and the cut-out lit. The cam surface iZti on the carrier H4 cooperates with a safety cam I24 in exactly the same manner described in connection with the safety cam 3I and surface 33 of Fig. 1.

A die member I30 is fixed to the head 20 which die member is provided with a bore I32 defining a peripheral wall having a relatively sharp inner edge corner I34 of such shape and configuration as to receive the member I therein with only shear clearance between the edges I34 and I02. Upon downward movement of the head 20 to its lowermost position it will be apparent that the edges I02 and I34 will cooperate to shear the waste material I08 from the work piece I06.

During operation of the device shown in Fig. 7, downward movement of the head 20 from the position shown will first cause the carrier H4 and punch lit to move inwardly and perforate the work piece. As soon as the camming mechanism 50 reaches a position comparable to that shown in Fig. 4 of the drawings, a spring or other suitable means (not shown) returns the slide a outwardly to its starting position as suggested by the full line of Fig. 4. In the event of failure of such spring, the safety cam I24 cooperating with the surface I20 insures return of the carrier to a position where the end of the punch H6 is clear of the path of movement of the die I30. Lateral perforation of the work piece and return of the carrier to its outermost position is accomplished before the lowermost end of the die I30 reaches the top of the punch II5 so that continued downward movement of the head 23 will have no further effect on the carrier H4 but will cause the die I30 to shear the waste material from the work piece. During the upward stroke of the head 20 the camming mechanism 40 will be merely withdrawn and the arm 52 thereof will be permitted to return to the position of Figs. 1 and 2 relative to the rest of the camming mechanism. After completion of each cycle of operation, the trimmed work piece I06 may be removed and a new work piece placed upon the support I30.

The camming mechanism of the presentinvention has been described in connection with a metal fabricating punch press merely for purpose of illustration and it will be obvious that the mechanism may be employed in many other machines without departing from the spirit of the present invention.

A limited number of specific embodiments have been described herein but it is to be understood that the invention is not limited thereto, such description being merely illustrative. The invention disclosed herein is to be limited only by the scope of the appended claims.

I claim:

l. A camming mechanism comprising, a pair of members relatively movable along a predetermined rectilinear path, one of said members being mounted for independent rectilinear movement transversely of said path, a certain one of said members being provided with a cam surface, the othe of said members carrying a cam mechanism having a cam element movable into engagement with said cam surface when said members are relatively moved along said path, to effect transverse movement of said one of said members, said cam element beingpivotally mounted on said mechanism, stop means on said mechanism, resilient means urging said pivoted cam element into engagement with said stop means, said stop means being so positioned as to prevent pivotal movement of said cam element away from said .cam surface when said element is in driving engagementwith said surface, said cam surface being fiat and extending diagonally of said path and said cam element being provided with a fiat surface for engaging said cam surface, said flat surface being parallel to said cam surface when said cam element engages said stop means, the arrangement being such that a line from the pivotal axis of said cam element to the center of said flat surface forms an acute angle with said surface on the side of said line opposite said stop means.

2. A mechanism as defined in claim 1 wherein said stop means and said cam element are provided with mating fiat surfaces substantially normal to said path when said surfaces are in engagement with each other.

3. A camming mechanism comprising, a pair of members relatively movable along one path and relatively movable along another path transverse to said one path, one of said members having a cam surface thereon extending diagonally of said one path and said other path, an elongated cam element pivoted adjacent one end thereof to the other of said members on an axis substantially normal to both said paths, cam surface engaging means at the other end of said cam element, stop means on said other member, resilient means pivotally urging said cam element into engagement with said stop means, said cam element engaging said stop means when said cam element lies nearly perpendicular to said cam surface.

4. A mechanism as defined in claim 3 wherein said parts are so arranged that said stop means prevents pivotal movement of said cam element away from said cam surface when said element engages said cam surface during movement of said members in one direction along said one path whereby said cam element will be effective to move said one member in one direction along said other path.

5. A mechanism as defined in claim 3 wherein a line extending from the center of contact between said cam element and said cam surface to the said axis is oblique to said cam surface.

6. A mechanism as defined in claim 3 wherein the center of contact of the said cam surface engaging means at the said one end of the cam element is transversely displaced from a radial line extending from said axis normal to said cam surface, said displacement being in a direction toward said stop means.

7. A mechanism as defined in claim 3 wherein the cam surface engaging means of said element is a fixed surface parallel to said cam surface when said element is in engagement with said stop means.

8. A mechanism as defined in claim 3 wherein the cam surface engaging means of said element comprises a roller journalled to said cam element at the said other end thereof.

9. A camming mechanism comprising, a pair of members relatively movable along one path and relatively movable along another path transverse to said one path, one of said members having a cam surface thereon extending diagonally of said one path and said other path, an elongated cam element pivoted adjacent one end thereof to the other of said members on an axis substantially normal to both said paths, cam surface engaging means at the other end of said cam element, the arrangement being such that when said engaging means of said element engages said cam surface a line normal to said cam surface and passing through the center of pressure of said cam surface engaging means passes to one side of said pivotal axis, stop means carried by said other member on said one side of said axis and in position to engage said element and limit pivotal movement thereof about said axis, and yieldable means urging said element toward said stop means.

10. In a punch press having a plunger movable toward and from a die along a predetermined path, said die being mounted for independent movement transversely of said path and being provided with a cam surface, the said plunger carryinga cam mechanism having a cam element movable into engagement with said cam surface when said plunger is moved along said path in one direction, to effect transverse movement of said die in a first direction, said cam element being pivotally mounted on said mechanism, stop means on said mechanism, resilient means urging said pivoted cam element into engagement with said stop means, said stop means being so positioned as to prevent pivotal movement of said cam element away from said cam surface when said element is in driving engagement with said REFERENCES CITED The following references are of record in the file of this patent UNITED STATES PATENTS Number Name Date 1,717,612 McNeil June 18, 1929 1,848,201 Rook Mar. 8, 1932 20 2,507,637 Krize May 16, 1950 FOREIGN PATENTS Number Country Date 836,683 France Jan. 24, 1939