US3659779A

US3659779A - Punch mechanism

Info

Publication number: US3659779A
Application number: US22961A
Authority: US
Inventors: John W Berkman; Lawrence R Gravell
Original assignee: International Business Machines Corp
Current assignee: International Business Machines Corp
Priority date: 1970-03-26
Filing date: 1970-03-26
Publication date: 1972-05-02
Anticipated expiration: 1989-05-02
Also published as: GB1331722A; DE2113374C3; DE2113374B2; JPS534440B1; DE2113374A1; FR2083914A5; IT984530B

Abstract

A punch mechanism including a line of punches each having an interposer disposed between it and reciprocating drive mechanism. The interposers are reciprocably disposed in slots in a guide block, being pivoted therein by virtue of end walls of the slots acting on the edges of the interposers. A pneumatic piston is provided for moving each of the interposers into alignment with the drive mechanism to cause a punching action, and permanent magnets are provided for moving and holding the interposers in their inactive positions.

Description

United States Patent Berkman et al.

[ 51 May 2,1972

[54] PUNCH MECHANISM [72] Inventors: John W. Berkman, Oronoco; Lawrence R.

Gravell, Rochester, both of Minn.

[73] Assignee: International Business Machines Corporation, Armonk, NYv

[22] Filed: Mar. 26, 1970 [21] App1.No 22,961

[52] U.S.Cl I ..234/ll4, 83/571 [51] Int. Cl. i 1 .G06k 1/02 [58] FieldofSearch. ..234/109,111,114,115,117,

[56] References Cited UNITED STATES PATENTS 3,412,932 11/1968 Masterson et a1 ..234/l15 3,291,388 12/1966 Pataki ..234/115 3,311,297 3/1967 Williams et al.. ...234/114 3,059,844 10/1962 Englund ...234/115 3,394,882 7/1968 Cattorini et a1 .234/119 Primary E.\uniilierjames M. Meister Anomey-Hunitin & Jancin and Keith T. Bleuer [57] ABSTRACT A punch mechanism including a line of punches each having an interposer disposed between it and reciprocating drive mechanism. The intcrposers are reciprocably disposed in slots in a guide block, being pivoted therein by virtue of end walls of the slots acting on the edges of the interposers. A pneumatic piston is provided for moving each of the interposers into alignment with the drive mechanism to cause a punching action, and permanent magnets are provided for moving and holding the interposers in their inactive positions 14 Claims, 4 Drawing Figures Patented May 2, 1972 2 Sheets-Sheet l ATTORNEY Patented May 2, 1972 2 Sheets-Sheet 2 FIG.3

PUNCH MECHANISM BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates to punch mechanism and particularly to such mechanism designed for punching lines of holes in document cards which represent data in coded form.

2. Description of the Prior Art It has been previously proposed in a patent to Jacob Rabinow, US. Pat. No. 3,104,053, that punches for docurnents may be electrically controlled and in particular that each of a plurality of punches shall have a magnet effective on it for moving the punches laterally as well as longitudinally. Some of the punches described in this patent are permanent magnets.

The patent to Masterson, US. Pat. No. 3,411,709, also describes the use of pennanent magnets in punch mechanism; and these magnets are effective on reciprocating interposers and tend to move the interposers out of motion-transmitting relationship with respect to reciprocable punches. Bucking windings are utilized on the permanent magnets for the purpose of allowing the interposers to move into motion-transmitting relationship with the respective punches.

It has also been proposed in the co-pending application of Baker et al, Ser. Number 746,514, filed July 22, 1968, for Electro-Mechanical Actuator, that flexible interposers movable into line with punches may be actuated by separate interposer link which in turn are actuated by electromagnets.

SUMMARY OF THE INVENTION It is a general object of the present invention to provide an improved low-cost, simple, and reliable punch mechanism.

More particularly, it is an object of the present invention to provide improved punch mechanism which includes pivotally movable interposers held in and movable into retracted nonpunching position by means of permanent magnets, with the retracting action of the magnets being overcome by interposer actuators such as pneumatic pistons.

It is still another object of the invention to provide an improved punching mechanism of this type in which the actuators are free floating within slots provided in a guide block so that relatively complicated connections need not be provided between the interposers and the respective punches.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view of punch mechanism incorporating the principles of the invention;

FIG. 2 is a side elevational view of the punch mechanism with portions of it being broken away to more clearly reveal internal parts of the mechanism; and

FIGS. 3 and 4 are respectively sectional views taken on line 3-3 and 44 of FIG. 1.

DETAILED DESCRIPTION Referring now to the drawings, the illustrated punch mechanism may be seen to comprise, in general, a housing 10, a stripper 12 disposed on the housing 10, a die 14 overlying the stripper 12, a die stiffener and support 16 with respect to which the die 14 is fixed, a plurality of punches 18 extending in a row through the stripper 12, a guide block 20 having a plurality of interposers 22 disposed therein, a pair of

permanent magnets

24 and 26 disposed in the block 20, a plurality of pneumatically actuated

pistons

28 and 29 in the block 20, an eccentric shaft 30 rotatably disposed in the housing 10, a bail 32 adapted to abut the interposers 22 for driving them upwardly and also for pulling the punches l8 downwardly, and drive mechanism 34 for reciprocating the bail 32 vertically.

The housing carries bushings 36 in which the shaft 30 is rotatably disposed. The drive mechanism 34 comprises a pair of yokes 38 each having an oblong opening 40 with flatted sides 40a. A bearing 42 is disposed in each of the openings 40 and has flatted sides 42a in sliding contact with the flatted sides 40a of the associated opening 40, and the bearing 42 is rotatably disposed on the round eccentric portion 30a of the shaft 30.

The bail 32 is fixed in the pair of yokes 38 and has an opening 32a therein for receiving the interposers 22. The lower edge 32b of the opening 32a, as will hereinafter appear, constitutes an abutting edge for the interposers 22; and the bail is provided with laterally extending portions 44 defined by slots 46 for embracing the punches 18. Each of the punches 18 has a land portion 18a of increased diameter underlying a pair of the bail portions 44 so that the portions 44, cooperating with the land portions 18a of the punches 18, in effect have a oneway engagement with the punches 18 for retracting the punches downwardly as shown in the figures. The bail 32 is reciprocably disposed in bearing blocks 48 carried by the housing 10.

The guide block 20 is provided with a plurality of vertically extending slots 50 interspaced with similar slots 52 which are offset with respect to the slots 50 as seen in FIG. 4. The slots 50 are each provided with a downwardly and outwardly extending side portion 50a and parallel side portions or walls 50b and 500, and the slots 52 are each provided with similar side portions but the slots 52 are reversed with respect to the slots 50.

An interposer 22 is slidably disposed in each of the

slots

50 and 52, and each of the interposers 22 is formed with a boss 54 on its upper end and with a notch 56 forming a horizontal ledge 56a adjacent the lower end of the interposer. The interposers 22 are reversed in the

consecutive openings

50 and 52 so that the bosses 54 extend in one direction in a slot 50 and the bosses 54 extend in the opposite direction in the adjacent slot 52. Each of the interposers 22 is of rigid magnetic material.

Each of the interposers 22 has an elongated opening 22a through it, and a rod 58 extends through the openings 22a of all of the interposers 22 and into the ends of the guide block 20.

The guide block 20 is of nonmagnetic material, and the

permanent magnets

24 and 26 are embedded within guide block 20 in the positions shown. It will be noted that the

magnets

24 and 26 extend parallel with the row of punches l8 and parallel with the interposers 22 which are in a similar row. The

magnets

24 and 26 are each magnetized so that their north and south poles appear on the long edges of the magnets 26 extending from one side edge of the magnet to the other and perpendicular to the punches l8; and, as shown in FIG. 1, the upper edges of the

magnets

24 and 26 constitute the north poles of the magnets. The

magnets

24 and 26 may, if desired, be reversed so that the north poles are on the bottom; or only one of the

magnets

24 and 26 may be reversed so that the north pole of one magnet is at the top while the north pole of the other magnet is at the bottom. It will be observed that the slots 50 are closer to the magnet 24 than to the magnet 26; and, correspondingly, the slots 52 are closer to the magnet 26 than to the magnet 24.

Auxiliary housing portions

60 and 62 are fixed onto the guide block 20, and the

pistons

28 and 29 are reciprocably disposed in cavities 64 formed in the guide block 20 and in the

portions

60 and 62. An opening 600 extends through the housing 60 in communication with each of the cavities 64. Each of the pistons 28 has a rod portion 28a adapted to make contact with one of the interpomrs 22 in a slot 50, and each of the pistons 29 has a similar rod portion 29a adapted to make contact with an interposer 22 disposed in one of the slots 52. A flexible diaphragm 66 is fixed between the guide block 20 and the housing portion 60, and a similar diaphragm is fixed between the guide block 20 and housing portion 62 for sealing the two sides of each of the cavities 64. It will be observed from FIG. 3 that the pistons 28 are elongated vertically with the major or long dimension of the pistons 28 extending parallel with the interposers 22, and the cavities 64 are of a similar elongated shape. The pistons 29 have the same shape as the pistons 28 with their receiving cavities 64 being of the same size and shape as the cavities 64 for the pistons 28; and the

pistons

28 and 29 alternate in disposition with respect to each other along the length of the guide block 20, with a piston 28 having its rod portion 28a extending into each slot 50 and with the rod portions 29a of the pistons 29 extending into the interspaced slots 52. This offset arrangement of the

pistons

28 and 29, together with the oblong shapes of the pistons, allows the

piston rods

28a and 29a, and

slots

50 and 52, and therefore the interposers 22 and punches 18 to be located quite close together.

The stripper 12 has a row of vertical openings 68 therethrough with plastic bushings 70 in the openings for receiving the punches 18 which are in a similar row. It is contemplated that there shall be sufficient frictional force of each bushing 70 on the punch 18 therein so that the punch 18 remains in its lowermost position even though the punch 18 and the stripper 12 may both be of magnetic material and may thus both be magnetized.

The die 14 has a row of die holes 140 therethrough which are in alignment with the openings in the bushings 70 so that the corresponding punch 18 may enter the die hole 140 with a punching action. The support 16 overlies much of the surface of the die 14 for supporting the die, and the support 16 is provided with a longitudinally extending slot 16a therein which is in communication with all of the openings 14a in the die 14 and by means of which the punchings may be removed. The die 14 is maintained with a small spacing from the stripper 12 by means of spacer plates 72 so that a record in the form of a document card 74, for example, may be moved between the die 14 and stripper 12 when the punches 18 are not in raised position.

In operation, the document card 74 is moved to a position beneath the die openings 14a. At this time, one or more of the

pistons

28 and 29 may be actuated by means of air pressure supplied through the corresponding opening 600 onto the diaphragm 66 and the piston 28 or piston 29 located within the corresponding cavity 64. The shaft 30 is continuously driven; and the eccentric shaft portion 300, acting through the bearings 42 on the horizontal sides 40a of the openings 40, causes the yokes 38 and thereby the bail 32 fixed to the yokes 38 to reciprocate verticallythe bail 32 sliding in the bearing block 48. The interposer corresponding to the piston 28 or piston 29, that has been actuated by means of air pressure, is thereby moved away from the edge 500 or corresponding edge in one of the slots 52 toward the center of the slot with the upper end of the interposer pivoting on the

slot end walls

50b and 50c. The boss 54 is rounded, as is the top edge of the interposer 22, to allow such pivotal movement of the interposer 22 within the

slot

50 or 52. The abutment edge 56a of the interposer is thus moved in alignment with the edge 32b of the bail 32. The interposer 22 is therefore moved upwardly on the next upward movement of the bail 32, and the interposer 22 moves the corresponding punch 18 upwardly so that the punch enters the corresponding die opening 140 and punches a corresponding hole in the document card 74. On the succeeding downward reciprocation of the bail 32, the portions 44 of the bail embracing the punch 18 pull the punch 18 downwardly by means of its land portion 18a out of punching relationship with respect to the corresponding die opening 140 so that the document card 74 may then be incremented into another punching relationship with respect to the die openings 14a.

When air pressure is released from the corresponding

piston

28 or 29, the corresponding

magnet

24 or 26 pulls the interposer 22 back into inoperative position, with the edge of the interposer 22 in bearing relationship with respect to the outwardly flaring edge 50a of the slot 50 or the corresponding outwardly flaring edge of the slot 52. Since the slots 50 and thereby the interposers 22 within these slots are located closer to the magnet 24 than to the magnet 26, the magnet 24 is effective to pull these interposers 22 back into inactive positions in which the ledges 560 are out of alignment with the edge 32b of the bail 32 and in which the interposers are in contact with the outwardly flaring side walls 500 of the slots 50. Likewise,

the magnet 26 is efiective on the interposers 22 within the slots 52 for retracting these interposers to inactive positions. Subsequently, when any of the

pistons

28 or 29 are actuated by air pressure, moving the

piston rods

28a and 29a into the corresponding

slots

50 or 52, movement of the corresponding interposers 22 is against the action of the

magnet

24 or 26 that has previously retracted the interposers into inactive positions and which yieldably holds the interposers in their inactive positions.

The above-described punch mechanism is advantageously a very low-cost, simple, and reliable mechanism. Although the pneumatically actuated

pistons

28 and 29 are disclosed for moving the interposers 22 into punching positions, it is apparent that electromagnetic actuators may be used instead of the

pistons

28 and 29. The interposers 22 and the punches 18 may be positioned very close together particularly in view of the fact that the

pistons

28 and 29 are of elongate shape with their greatest dimensions in the vertical direction. Also, in order to provide a substantial number of interposers 22 and punches 18 in line, half of the pistons (pistons 28) are provided on one side of the interposers and punches while the other half of the pistons (pistons 29) are disposed on the other side of the interposers and punches, the

pistons

28 and 29 in effect being alternated with respect to the interposers and punches.

in view of the fact that the interposers 22 are in sliding contact with and are thereby pivoted with respect to the vertical parallel side walls 5% and 50c of the slots 50 and the corresponding side walls of the slots 52 rather than actual pivots of the interposers on the punches 18 being provided, a lowcost and simple construction is assured in which the interposers 22 are out of the way of bail 32 when punching is not intended. Advantageously, the interposers 22 have no movement when punching by the respective interposers is not intended, since the construction is such that the bail 32 only moves the interposers 22 when the ledges 56a are in alignment with the bail edge 32b. The interposers are effectively free floating in their

slots

50 and 52 and are trapped in these slots in ordinary operation of the mechanism due to magnetic action of the

magnets

24 and 26; and the

magnets

24 and 26 which are in the form of elongate bars extending parallel with the rows of punches 18 and interposers 22 and which are on opposite sides of the row of interposers and are fixed in the guide block 20, provide a simple construction for yieldably holding the interposers retracted. The rod 58, passing through the openings 22a in the interposers, holds the interposers within the

slots

50 and 52 until full disassembly of the interposers 22 with respect to the guide block 20 is desired.

it is to be understood that the invention is not be limited to the specific constructions and arrangements shown and described, except only insofar as the claims may be so limited, as it will be apparent to those skilled in the art that changes may be made without departing from the principles of the invention.

What is claimed is:

l. Thrust transmission mechanism comprising:

a reciprocable work element;

a reciprocable drive element and means for reciprocating the drive element;

an interposer of magnetic material arranged to move into and out of alignment with one of said elements, and when in alignment therewith, transmitting thrust from said drive element to said work element;

a magnet disposed in close proximity to and acting magnetically on said inteiposer for moving it out of a first one of its said positions and into a second one of its said positions;

a movable thrust rod efi'ective on said interposer for moving the interposer against the action of said magnet into alignment with said one element; and

a motor connected to and effective on said thrust rod for moving said interposer into alignment with said one element.

2, Thrust transmission mechanism as set forth in claim l and including a plurality of additional reciprocable work elements in addition to said first-named work element, said work elements being in alignment in a row and the thrust transmission mechanism including also an interposer similar to said firstnamed interposer and a thrust rod and motor similar to said first-named thrust rod and motor corresponding to each one of said additional work elements, said drive element and said magnet being effective on the additional ones of said interposers as on said first'named interposer as aforesaid.

3. Thrust transmission mechanism comprising:

a reciprocable work element:

a reciprocable drive element and means for reciprocating the drive element:

an interposer arranged to move into aligned position and out of aligned position with one of said elements and, when in alignment therewith, transmitting thrust from said drive element to said work element, said interposer including magnetic material;

a magnet effective magnetically on said interposer for moving it out of a first one of its said positions into a second one of its said positions; and

an actuator for moving said interposer from its said second position back to its said first position, said thrust transmission mechanism including a plurality of additional reciprocable work elements in addition to said firstnamed work element, said work elements being in alignment in a row and the thrust transmission mechanism including also an interposer similar to said first-named interposer and an actuator similar to said first-named actuator corresponding to each one of said additional work elements, said drive element and said magnet being effective on the additional ones of said interposers and on said first-named interposer as aforesaid, said interposers being in a row corresponding to the row of work elements, said actuators each being in the form of an oblong shaped, pneumatically actuated piston which has its major dimension parallel with said interposers, alternate ones of said pistons being disposed on one side of the row of interposers and the others of said pistons being disposed on the other side of the row of interposers.

4i Thrust transmission mechanism as set forth in claim 2, said drive element constituting a bail having a thrust-transmitting edge effective for engaging said interposers and extending around said interposers to provide a one-way engagement with said work elements so as to retract said work elements to nonworking positions on reciprocation of said drive element.

5. Thrust transmission mechanism comprising:

a reciprocable work element;

a reciprocable drive element and means for reciprocating the drive element;

a magnet effective magnetically on said interposer for moving it out of a first one of its said positions into the second one ofits said positions; and

an actuator for moving said interposer from its second position back to its said first position, said magnet being of a permanenet type and magnetically moving said interposer out of aligned position with said one element, said actuator being effective for moving said interposer back into alignment with said one element against the magnetic action of said magnet, said mechanism including a guide block having a slot therein for receiving said interposer, said interposer being of rigid magnetic material and said slot having parallel sidewalls between which said interposer fits in sliding relationship whereby to pivotally mount said interposer in said slot.

6. Thrust transmission mechanism as set forth in claim 5, said mechanism also including a plurality of work elements similar to said first-named work element, said work elements being disposed in a row, said mechanism also including an interposer and an actuator for each of said additional work elements which are similar to said interposer and said actuator for said first-named work element, said guide block including additional slots for said additional interposers similar to said first-named slot, said magnet being effective on substantially one-half of said interposers and said mechanism including a second similar magnet effective on the others of said interposers, said magnets being mounted in said guide block and extending parallel to said row of work elements.

7. Thrust transmission mechanism as set forth in claim 6, said magnets being in the form of elongate bars disposed on opposite sides of the row of work elements and each having its north pole on an edge extending generally parallel with the row of work elements.

8. Thrust transmission mechanism as set forth in claim 1, said magnet being of a permanent type and magnetically moving said interposer out of aligned position with said one element, said thrust rod and motor being effective for moving said interposer back into alignment with said one element against the magnetic action ofsaid magnet.

9. Thrust transmission mechanism as set forth in claim 8, said one element with respect to which said magnet is effective for moving said interposer out of alignment constituting said reciprocable drive element and said thrust rod and motor being effective to move said interposer back into alignment with said reciprocable drive element.

10. Thrust transmission mechanism comprising:

a reciprocable work element;

a reciprocable drive element and means for reciprocating the drive element;

a magnet effective magnetically on said interposer for moving it out ofa first one of its said positions into the second one of its said positions; and

an actuator for moving said interposer from its said second position back to its said first position;

said magnet being of a permanent type and magnetically moving said interposer out of aligned position with said one element;

said actuator being effective for moving said interposer back into alignment with said one element against the magnetic action of said magnet, said one element with respect to which said magnet is effective for moving said interposer out of alignment constituting said reciprocable drive element and said actuator being effective to move said interposer back into alignment with said reciprocable drive element;

said interposer being of rigid magnetic material and being pivotally mounted at one end to be in permanent alignment with said work element;

said actuator being effective on the other end of said interposer for moving it into alignment with said drive element.

ll. Thrust transmission mechanism as set forth in claim 10, said work element constituting a punch and said mechanism including a die into which said punch is thrust when said actuator is effective for moving said interposer,

l2. Thrust transmission mechanism as set forth in claim 10 and including a plurality of additional reciprocable work elements in addition to said first-named work element, said work elements being in alignment in a row and the thrust transmission mechanism including also an interposer similar to said first-named interposer and an actuator similar to said firstnamed actuator corresponding to each one of said additional work elements, said drive element being effective on all of said interposers and said magnet also being efiective on substantially oneehalf of said interposers, said mechanism also including a second magnet which is effective on the others of said interposers.

13. Thrust transmission mechanism as set forth in claim 10, said drive element including a bail which is interconnected

Claims

1. Thrust transmission mechanism comprising: a reciprocable work element; a reciprocable drive element and means for reciprocating the drive element; an interposer of magnetic material arranged to move into and out of alignment with one of said elements, and when in alignment therewith, transmitting thrust from said drive element to said work element; a magnet disposed in close proximity to and acting magnetically on said interposer for moving it out of a first one of its said positions and into a second one of its said positions; a movable thrust rod effective on said interposer for moving the interposer against the action of said magnet into alignment with said one element; and a motor connected to and effective on said thrust rod for moving said interposer into alignment with said one element.

2. Thrust transmission mechanism as set forth in claim 1 and including a plurality of additional reciprocable work elements in addition to said first-named work element, said work elements being in alignment in a row and the thrust transmission mechanism including also an interposer similar to said first-named interposer and a thrust rod and motor similar to said first-named thrust rod and motor corresponding to each one of said additional work elements, said drive element and said magnet being effective on the additional ones of said interposers as on said first-named interposer as aforesaid.

3. Thrust transmission mechanism comprising: a reciprocable work element: a reciprocable drive element and means for reciprocating the drive element: an interposer arranged to move into aligned position and out of aligned position with one of said elements and, when in alignment therewith, transmitting thrust from said drive element to said work element, said interposer including magnetic material; a magnet effective magnetically on said interposer for moving it out of a first one of its said positions into a second one of its said positions; and an actuator for moving said interposer from its said second position back to its said first position, said thrust transmission mechanism including a plurality of additional reciprocable work elements in addition to said first-named work element, said work elements being in alignment in a row and the thrust transmission mechanism including also an interposer similar to said first-named interposer and an actuator similar to said first-named actuator corresponding to each one of said additional work elements, said drive element and said magnet being effective on the additional ones of said interposers and on said first-named interposer as aforesaid, said interposers being in a row corresponding to the row of work elements, said actuators each being in the form of an oblong shaped, pneumatically actuated piston which has its major dimension parallel with said interposers, alternate ones of said pistons being disposed on one side of the row of interposers and the others of said pistons being disposed on the other side of the row of interposers.

4. Thrust transmission mechanism as set forth in claim 2, said drive element constituting a bail having a thrust-transmitting edge effEctive for engaging said interposers and extending around said interposers to provide a one-way engagement with said work elements so as to retract said work elements to nonworking positions on reciprocation of said drive element.

5. Thrust transmission mechanism comprising: a reciprocable work element; a reciprocable drive element and means for reciprocating the drive element; an interposer arranged to move into aligned position and out of aligned position with one of said elements and, when in alignment therewith, transmitting thrust from said drive element to said work element, said interposer including magnetic material; a magnet effective magnetically on said interposer for moving it out of a first one of its said positions into the second one of its said positions; and an actuator for moving said interposer from its second position back to its said first position, said magnet being of a permanenet type and magnetically moving said interposer out of aligned position with said one element, said actuator being effective for moving said interposer back into alignment with said one element against the magnetic action of said magnet, said mechanism including a guide block having a slot therein for receiving said interposer, said interposer being of rigid magnetic material and said slot having parallel sidewalls between which said interposer fits in sliding relationship whereby to pivotally mount said interposer in said slot.

8. Thrust transmission mechanism as set forth in claim 1, said magnet being of a permanent type and magnetically moving said interposer out of aligned position with said one element, said thrust rod and motor being effective for moving said interposer back into alignment with said one element against the magnetic action of said magnet.

10. Thrust transmission mechanism comprising: a reciprocable work element; a reciprocable drive element and means for reciprocating the drive element; an interposer arranged to move into aligned position and out of aligned position with one of said elements and, when in alignment therewith, transmitting thrust from said drive element to said work element, said interposer including magnetic material; a magnet effective magnetically on said interposer for moving it out of a first one of its said positions into the second one of its said positions; and an actuator for moving said interposer from its said second position back to its said first position; said magnet being of a permanent type and magnetically moving said interposer out of aligned position with said one element; said actuator being effective for moving said interposer back into alignment with said one element against the magnetic action of said magnet, said one element with respect to which said magnet is effective for moving said interposer out of alignment constituting said reciprocable drive element and said actuator being effective to move said interposer back into alignment with said reciprocable drive element; said interposer being of rigid magnetic material and being pivotally mounted at one end to be in permanent alignment with said work element; said actuator being effective on the other end of said interposer for moving it into alignment with said drive element.

11. Thrust transmission mechanism as set forth in claim 10, said work element constituting a punch and said mechanism including a die into which said punch is thrust when said actuator is effective for moving said interposer.

12. Thrust transmission mechanism as set forth in claim 10 and including a plurality of additional reciprocable work elements in addition to said first-named work element, said work elements being in alignment in a row and the thrust transmission mechanism including also an interposer similar to said first-named interposer and an actuator similar to said first-named actuator corresponding to each one of said additional work elements, said drive element being effective on all of said interposers and said magnet also being effective on substantially one-half of said interposers, said mechanism also including a second magnet which is effective on the others of said interposers.

13. Thrust transmission mechanism as set forth in claim 10, said drive element including a bail which is interconnected with said work element for pulling said work element back to a nonworking position on reciprocation of said drive element.

14. Thrust transmission mechanism as set forth in claim 13, said actuator constituting a pneumatically actuated piston.