US3863486A

US3863486A - Transfer press

Info

Publication number: US3863486A
Application number: US430883A
Authority: US
Inventors: Donald Richard Lassy
Original assignee: Individual
Current assignee: Individual
Priority date: 1974-01-04
Filing date: 1974-01-04
Publication date: 1975-02-04
Anticipated expiration: 1992-02-04

Abstract

A transfer press has a plurality of individual cam-operated plungers supported for vertical reciprocating movement. Each plunger has associated downstroke and lifting cams. Upward motion of the plunger is controlled by the lifting cam which engages an associated lifting rod mechanism connected to the plunger. An adjustable friction device mounted on the machine frame above the upper cross member thereof frictionally engages the lifting rod mechanism to further control plunger movement. The lifting rod mechanism has an adjustable limit stop assembly associated therewith to accurately control the downstroke of its associated plunger.

Description

United States Patent 3,863,486

Lassy Feb. 4, 1975 TRANSFER PRESS [57] ABSTRACT lnvemofl Donald Richard 22 Matthews A transfer press has a plurality of individual camw Terri/V1116, Conn- 06786 operated plungers supported for vertical reciprocating [22] Filed: Jam 4, 1974 movement. Each plunger has associated downstroke and lifting cams. Upward motion ofthe plunger is con PP .1 3 ,833 trolled by the lifting cam which engages an associated lifting rod mechanism connected to the plunger. An

52 US Cl. "12/405,72/452 adjustable friction device mounted the machine 51 int. Cl B21j 9/18, B21 j 13/00 frame ahOve the h P memher hereof {fiction- [58] Field of Search 72/405, 452, 404 ally engages the hfhhg mechamsm further trol plunger movement. The lifting rod mechanism has [56] References Cited an adjustablle limit stlot;l assembly ;als(s0citated therewitg to accurate y contro t e ownstro e 0 its associate UNITED STATES PATENTS plungen 3,199,358 8/1965 Bradlee 72/452 X 3,596,498 8/197l Bradlee 72/405 17 Claims, 5 Drawing Figures Primary Examiner-Milton S. Mehr Attorney, Agent, or FirmMcCormick, Paulding & Huber PATENTEI] FEB 4mm TRANSFER PRESS BACKGROUND OF THE INVENTION This invention relates in general to metal working presses and deals more particularly with an improved transfer press or eyelet machine of the type which includes a plurality of individual cam operated plungers.

In a machine of the aforedescribed general type, each plunger is driven during its downstroke by an associated plunger cam. The upward motion of the plunger is controlled by a lifting cam which operates an associated lifting rod mechanism connected to the plunger. An adjustable friction device frictionally engages the lifting rod mechanism and acts as a brake thereon so that the plunger follows the plunger cam during its down-stroke. The friction device also prevents the plunger from dropping during a portion of the press cycle when the lifting cam is out of engagement with the lifting rod assembly. Improper or loose friction device adjustment may result in excessive plunger travel during the down-stroke. More specifically, if the friction device fails to exert the desired braking effect upon an associated plunger, the inertial force acting upon the plunger may cause it to lead rather than follow its associated plunger cam. The latter condition may cause excessive workpiece tolerances which result in unacceptable workpieces and consequent lost production. The frictional devices also generate considerable heat which presents lubricational problems and tends to reduce the life bearings, bushings and various moving parts.

The present invention is concerned with improvements in transfer presses or eyelet machines wherein the aforedescribed general problems are overcome by improved arrangements of friction devices for more efficient heat dissipation and provision of means to accurately control plunger down-stroke.

SUMMARY OF THE INVENTION In accordance with the present invention, a transfer press is provided which includes a plurality of individual cam operated plungers, each plunger having a lifting rod mechanism connected thereto for imparting upward motion to the plunger in response to rotation of an associated lifting cam. Frictional devices associated with the lifting rod mechanisms and mounted on the press frame above the top cross member thereof frictionally engage the lifting rod mechanisms above the latter cross member. Each lifting rod mechanism has a limit stop assembly associated therewith for accurately controlling the down-stroke of an associated plunger.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a somewhat schematic fragmentary front elevational view of a transfer press embodying the present invention.

FIG. 2 is a somewhat schematic sectional view taken generally along the line 22 of FIG. 1.

FIG. 3 is a somewhat enlarged sectional view taken along the line 33 of FIG. 2.

FIG. 4 is a front elevational view of an upper limit stop.

FIG. 5 is a fragmentary sectional view taken along the line 5-5 of FIG. 3.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Turning now to the drawings and referring first particularly to FIGS. 1 and 2, a transfer press or eyelet machine embodying the present invention and indicated generally by the reference numeral 10 comprises a frame 12 which supports a plurality of individual cam operated plungers l4, 14 for vertical reciprocal movement. Each plunger is driven during its down-stroke by an associated plunger cam 16 mounted on a cam shaft 18 which extends transversely of the machine frame. The upward motion of each plunger is controlled by a lifting cam 20 mounted on the cam shaft 18 and engageable with an associated lifting rod mechanism indicated generally at 22 and connected to the plunger. In accordance with the present invention, each lifting rod mechanism 22 has a friction device 24 associated therewith and mounted on the uppermost frame cross member for frictional engagement with the lifting rod mechanism above the latter cross member. Further, and in accordance with the invention, each lifting rod mechanism has a limit stop assembly associated therewith and indicated generally at 26 to accurately control the downstroke of an associated plunger 14, as will be hereinafter further discussed.

Considering now the press 10 in further detail, the frame 12 includes a pair of upright side members 28 (one shown), connected by a plurality of integral horizontal cross members which include the

members

30, 32, 34 and 36. The

plungers

14, 14 are supported for vertical reciprocal sliding movement by the

cross members

30 and 32, substantially as shown. The cam shaft 18 is journalled on the frame, extends transversely thereof between the

cross members

32 and 34 and carries the

plunger cams

18, 18 and the

lifting cams

20, 20 which are keyed thereto and arranged in alternate series therealong.

Considering now a typical plunger 14 and its associated lifting rod mechanism 22 and referring particularly to FIG. 2, the illustrated plunger 14 comprises a generally cylindrical member supported for vertical sliding movement by and relative to the

cross members

30 and 32 and has a cam follower 3L8 coaxially received in a bore in its upper end. A wedge or tapered key 40 extends transversely through vertical slots in the plunger and engages the lower end of the cam follower 38 for adjusting tool shut height. At its lower end, the plunger 14 has a draw punch 44 which cooperates with a die 46 to blank or form a workpiece W, as is well knownin the art. The plunger 14 has a conventional stripper 48 associated therewith which carries a strip per sleeve to prevent the workpiece W from moving upward with the draw punch 44.

The lifting rod assembly 22, includes a vertically extending lifting rod 50 supported for reciprocal vertical sliding movement by the

cross members

30, 32, 34 and 36 substantially as shown. A lifting arm 52 releasably connected to the rod 50 extends radially outwardly therefrom above and in general alignment with the lifting cam 20. The rod is connected to the plunger between the

cross members

30 and 32 by a transversely offset connecting member 54.

In accordance with the invention, the friction device or friction is mounted on the cross member at the upper terminal end of the frame and engages an associated lifting rod mechanism above the latter cross member. A typical friction 24, as shown in FIG. 2, comprises a pair of

friction pads

56 and 58 adjustable to frictionally engage the free end of the illustrated lifting rod 50 by spring-loaded

screws

60, 60. The friction 24 is maintained in a substantially fixed position relative to the machine frame by a block 62 mounted on the cross member 36. The latter block carries a pair of transversely spaced fingers 64, 64 (one shown) respectively received in slots opening outwardly through opposite sides of the

friction pads

58 and 56, in a manner well known in the art.

Considering now the limit stop assembly in further detail, and referring particularly to FIGS. 3-5, the limit stop assembly 26 includes an adjustable upper stop member designated generally by the numeral 66 mounted on the lifting rod assembly 22 for movement therewith and a lower stop member indicated generally at 68 and mounted on the frame 12. The upper stop member 66 cooperates with the lower stop member 68 to limit the downward travel of an associated plunger 14.

The upper stop member 66 comprises a rectangular body 70 and a screw 72 which is received in a threaded opening 73 formed in the body which extends therethrough. The screw has an abutment surface 74 at its lower end. An indicator or dial 76 mounted in fixed position at the upper end of the screw has indicia or graduations 78, 78 thereon which cooperate with a reference marker 80, mounted in fixed position on the body 70, to indicate relative change in the position of the abutment 74 when the screw 72 is turned. Preferably, and as shown, the screw 72 has a diametral pitch of .050 inches so that each complete revolution of the indicator dia] 76 moves the abutment surface 74 in an axial direction through 0.050 inches. The illustrated indicator dial 76 has fifty graduations thereon, each graduation being equivalent to 0.001 inches. The body 70 has a bore 82 axially parallel to the screw 72 for receiving the rod 50 therethrough and a slot 84 which extends in an axial directon through the body and communicates with the bore 82. A clamping screw 86 extends transversely of the slot 84 to releasably secure the body 70 in axially parallel relation to the rod. Another slot 85 extends in an axial direction through the body 70 and communicate with the threaded opening 73. Another clamping screw 87 extends transversely of the-latter slot and threadably engages the body for clamping the screw 72 in selected angular position relative to the body.

The lower stop member 68 generally comprises a rectangular block 88 mounted on the cross member 34. The block 88 has a generally downwardly opening cylindrical recess 90 therein. A plunger 92 received within the recess has an enlarged head disposed within the recess 90 and a cylindrical shank which projects coaxially upward through a cylindrical opening in the upper wall block 88. At its upper end, the plunger 92 has an abutment 94 generally coaxially aligned with the abutment 74 on the screw 72. The lower stop member 68 further includes a plug 96 threadably received in the lower end of the bore 90. A compression spring 98 acts between the plug and the enlarged head of the plunger 92 to yieldably support the plunger within the block 88.

Further referring to FIG. 2, at the beginning of a plunger cycle, the plunger 14 is in its raised or broken line position. The friction 24 engages and frictionally grips the upper end of the lifting rod 50 to counterbalance the plunger 14 and lifting rod assembly 22 and hold the plunger in its fully raised position while the lifting cam rotates out of engagement with the lifting arm 52 and the plunger cam 16 comes into engagement with the follower 38. While the plunger 14 dwells in its fully raised position, transfer fingers associated with the die 46 transfer each workpiece, such as the workpiece W, from one die station to the next successive one. The plunger is driven downwardly against the action of the friction 24 by the plunger cam 18. The limit stop assembly 26, is adjusted so that the abutment 74 on the upper limit stop engages the abutment 94 on the lower limit stop when the plunger 14 reaches the lower limit of its downstroke as determined by the cam 18. If the friction 24 should be too loosely adjusted, the limit stop assembly 26 will prevent plunger overtravel or excessive plunger downstroke. The plunger 14 is raised by engagement of the lifting cam 20 with the lifting arm 52. During a portion of its rotational cycle the lifting cam 20 elevates the plunger to a partially raised position wherein the draw punch 44 is at least partially disposed within the workpiece W. The plunger dwells in the latter position while the transfer fingers associated with the die block 46 engage the workpiece W. Thereafter, the lifting cam elevates the plunger 14 to its fully raised position to complete the cycle. During the latter portion of the cycle, the stripper sleeve carried by the stripper arm 48 engages the workpiece W to prevent it from being carried upwardly with the draw punch 44.

Since the limit stop 26 may be adjusted to assure positive control of the plunger downstroke, the friction 24 need not be wholly relied upon for this purpose. Thus, the press may be operated with the frictions adjusted for relatively light frictional engagement with the lifting rods thereby reducing the quantity of frictional heat generated by the frictions during operation. Further, it should be noted that the location of the frictions above the press frame assures efficient heat dissipation and eliminates the risk of critical moving parts of the machine being exposed to excessive heat.

The adjustable limit stop assembly 26 is also employed to facilitate rapid accurate adjustment of tool shut height. To save time and eliminate guess work in adjusting the wedge 40 to increase the depth of draw punch penetration, the plunger 14 is first set at the bottom of its stroke. The screw 72 is then adjusted so that the abutment 74 thereon engages the abutment 94 on the bottom stop member. A first reading of the graduated dial 76 is then noted. After the dial has been read, the screw 72 is rotated to raise the abutment 74 or back it away from the abutment 94, a distance greater than the desired tool shut adjustment. The wedge 40 may then be adjusted to lower the draw punch 44. Since the lifting arm 52 is connected to the plunger 14, lowering the plunger will also lower the lifting arm and the upper limit stop associated therewith. After an adjustment has been made, the screw 72 is again rotated to bring the abutment 74 into engagement with the abutment 94. A second reading of the indicator dial 76 is then taken. The difference between the said first and second dial readings indicates the plunger adjustment attained by adjusting the wedge 40.

I claim:

1. In a transfer press having a frame, a plunger supported on said frame for movement in one and an opposite direction relative thereto, a lifting rod mechanism supported on said frame and including a lifting rod disposed in axially parallel relation to said plunger and connected thereto for movement therewith, a cam shaft supported on said frame for rotation relative thereto, a plunger cam mounted in fixed position on said shaft for rotation therewith and engagable with said plunger for positively driving it in said one direction in response to rotation of said shaft, a lifting cam mounted in fixed position on said shaft for rotation therewith and engagable with said lifting rod mechanism to drive said plunger in said other direction in response to rotation of said shaft, and friction means mounted on said frame and frictionally engaging said lifting rod to resist movement thereof relative to said frame, the improvement comprising a limit stop assembly including an upper stop member defining a first abutment, means for securing said upper stop member to said lifting rod assembly for movement therewith, and means defining second abutment associated with said frame and in the path of said first abutment for engagment with said first abutment to limit movement of said plunger in said one direction.

2. In a transfer press as set forth in claim 1, the combination which includes means for moving one of the abutments which comprises said first and second abutments generally toward and away from the other of said abutments to vary the limit of movement of said plunger in said one direction.

3. In a transfer press as set forth in claim 2, the combination wherein said limit stop assembly includes a lower stop member which defines said second abutment and one of said stop members includes a screw which comprises said means for moving said one abutment.

4. In a transfer press as set forth in claim 3, the combination wherein said upper stop member comprises said one stop members and said securing means comprises means for securing said upper stop members to said lifting rod with said screw in generally axially parallel relation to said rod.

5. In a transfer press as set forth in claim 3, the combination wherein said one stop member includes a body which has a reference marker thereon and said screw extends through said body and has one end portion which defines said one abutment and an indicator thereon which cooperates with said reference marker to indicate the relative position of said one abutment.

6. In a transfer press as set forth in claim 5 wherein said indicator comprises a dial mounted on the other end of said screw which has indicia of abutment position thereon.

7. In a transfer press as set forth in claim I, the combination which includes means for yieldably supporting one of the abutments which comprise said first and second abutment.

8. In a transfer press as set forth in claim 7, the combination wherein said means defining said one abutment comprises a plunger element and means supporting said one abutment comprises a spring supporting said plunger element.

9. In a transfer press as set forth in claim 8, the combination wherein said limit stop assembly includes a lower stop member which has a body, said body has a recess therein, said plunger element includes an enlarged head received in said recess and a shank which projects from said body and defines said one abutment, and said spring is received in said recess and bears against said enlarged head.

10. In a transfer press as set forth in claim 9, the combination wherein said lower stop member includes means for retaining said plunger element and said spring in assembly with said body.

11. In a transfer press as set forth in claim 10, the combination wherein said spring comprises a compression spring acting between said retaining means and said plunger element, said retaining means comprises means for varying the compressive force applied by said spring to said plunger element.

12. In a transfer press as set forth in claim 11, the combination wherein said retaining means comprises a plug which threadably engages said body within said recess.

13. In a transfer press as set forth in claim 1, wherein said frame has a cross member at its upper terminal end, the further improvement wherein said friction means is mounted on said frame and engagable with said lifting rod above said cross member.

14. In a transfer press as set forth in claim 1, the further improvement wherein said frame has a first cross member extending transversely thereof above said cam shaft and generally parallel thereto and a second cross member extending transversely thereof above said first cross member, said upper stop member is secured to said lifting rod between said first and second cross members, and said friction means is mounted on said frame and engagable with said lifting rod above said second cross member.

15. In a transfer press comprising a frame having a plurality of vertically spaced apart horizontally disposed cross members extending transversely thereof and including a first cross member at its upper terminal end, a vertically elongated plunger supported on said frame for axially vertical movement in one and an opposite direction relative thereto, a lifting rod mechanism supported on said frame and including a lifting rod disposed in axially parallel relation to said plunger and connected thereto for movement therewith, a horizontally disposed cam shaft supported on said frame and extending transversely thereof below said first cross member for rotation relative thereto, a plunger cam mounted in fixed position on said shaft for rotation therewith and engageable with said plunger for positively driving it in a downward direction in response to rotation of said shaft, a lifting cam mounted in fixed position on said shaft for rotation therewith and engageable with said lifting rod mechanism to drive said plunger in an upward direction in response to rotation of said shaft, and friction means mounted on said frame and frictionally engaging said lifting rod to resist movement thereof relative to said frame, the improvement wherein said lifting rod has a free end portion which extends upwardly beyond said first cross member and said friction means is mounted on said first cross member and engages said free end portion above said first cross member.

16. In a transfer press as set forth in claim 15, the combination wherein said frame includes a second cross member disposed below said first cross member and a third cross member disposed below said second cross member, said lifting rod is supported by said first, second and third cross members, and said cam shaft extends transversely of said frame between said second and third cross members.

17. In a transfer press as set forth in claim 16, the combination wherein said frame includes a fourth cross member disposed below said third cross member, said lifting rod is further supported by said fourth cross member, and said plunger is supported by said third and fourth cross members.

Claims

7. In a transfer press as set forth in claim 1, the combination which includes means for yieldably supporting one of the abutments which comprise said first and second abutment.