US2883666A

US2883666A - Electrically operated stapler with movable anvil

Info

Publication number: US2883666A
Application number: US488481A
Authority: US
Inventors: Harry O Moore
Original assignee: SILABERT CORP
Current assignee: SILABERT Corp
Priority date: 1955-02-16
Filing date: 1955-02-16
Publication date: 1959-04-28
Anticipated expiration: 1976-04-28

Description

April 28, 1959 H. o. MOORE 2,383,666

ELECTRICALLY OPERATED STAPLER WITH MOVABLE ANVIL 2 Sheets-Sheet 1 Filed Feb. 16, 1955 i 312 "L4 -a% L Y INVENTOR. v \22 B6 50 E HARRY O. MOORE ATTORNEYS April 28, 1959 H. o. MO ORE 2,883,666

' ELECTRICALLY OPERATED STAPLER WITH MOVABLE ANVIL Filed Feb. 16, 1 955 2 Sheets-Sheet 2 INVENTOR. HARRY O. MOORE.

l r 5 l ATTORNEYS United States Patent ELECTRICALLY OPERATED STAPLER WITH MOVABLE AN VIL Harry 0. Moore, Charlotte, N.C., asslgnor to Silabert Corporation, Charlotte, N.C., a corporation of. North Carolina Application February 16, 1955,,Serial No. 488,481 8 Claims. (Cl. 1---3) This invention relates to stapling machines, particularly of the type used for attaching adjacent components of relatively large objects, such as paper board containers and the like. This application is a continuation-in-part of my co-pending application entitled Electrical Actuator for Staplers, Serial Number 444,873, filed July 21, 1954, which is now Patent No. 2,766,293.

The apparatus disclosed in said co-pending application includes a mounting for a stapler of the usual handoperated type provided with electrically controlled means for actuating the stapler. However, the stapler head, from which the staples are discharged is normally positioned in relatively closely spaced relationship above the stapler anvil when in inoperative position and, consequently, it is difiicult to insert elements which are to be stapled together between the stapler head and the anvil of the prior stapling machines, such. as that disclosed in said co-pending application. This is particularly true in stapling the bottom flaps of a paper board carton together, since it is necessary to insert the side wall of such a container or carton between the stapler head and the anvil and to then-turn the container so as to insert the bottom flaps of such a carton or container etween the stapler head and the anvil before actuating the stapler.

It. is therefore an object of this invention to provide a movable anvil for a stapling machine which is movable into and out of operative position; that is, into and out of the vertical plane of the staple discharging end of the stapler head so the movable anvil may be positioned to one side of the vertical plane of the stapler head during the insertion of sheets or the walls of paperboard containers or other objects to be interconnected between the stapler head and the anvil, whereupon the anvil may then be moved into operative position in alinement with the staple discharging end of the stapler head prior to actuation of the stapler.

It is another object of this invention to provide apparatus of the character described wherein electrically operable means are provided for automatically moving the movable anvil from a normal inoperative position to operative position immediately prior to movement of the stapler head into engagement with the anvil and the consequent discharging-of a staple therefrom, each time the stapler is actuated.

It is still another object of this invention to provide a stapling machine having a substantially U-shaped frame having front and rear vertically spaced uprising legs thereon, to the rear leg of which an arm of a stapler head is pivotally connected. The front end of said arm has a stapler head thereon which is moved downwardly with the arm by electrically operable meansin the course 2,883,666 Patented Apr. 28, .1959

ice

of actuation of the stapler. The front arm of sai'd stapler, whose upper end terminates on a lower level than the upper end of the rear leg, has the medial portion of a tiltable anvil supporting lever fulcrumed thereon whose lower portion has a shaft therein which extends through an angularly disposed slot in a vertically movable anvil control element which is normally biased upwardly and thereby normally holds the anvil in the inoperative position. switch imparts downward movement to the control element to cause the anvil to move into operative position upon the switch to the solenoid being closed. A second switch is then closed to energize a second solenoid for actuating the stapler.

Some of the objects of the invention having been stated, other objects will appear as the description proceeds when taken: in connection with the accompanying drawings, in which: 7

Figure l is a side elevation of thestapling machine showing the improved movable anvil support thereon;

Figure 2 is a fragmentary view looking at the rear end of the stapling machine substantially along the line 2-2. in Figure 1;

Figure. 3 is a fragmentary elevation looking: substantially along line 3-3 in Figure 1 with a portion of the frame broken. away;

Figure 4 is a top. plan view of the structure shown in Figure 1 with a portion of the switchasupporting platform broken away; I

Figure 5 is an enlarged fragmentary elevation looking substantially along line 5-5 in-Figure l but showing the anvil-supporting lever in vertical or operative position relative to the front upstanding arm ofthe frame;

Figure 6 is a fragmentary vertical'fsectional view taken substantially along the'line 6-6 in Figure 5;

Figure 7 is a view similar to Figure 6, but showing the anvil and supporting .lever therefor in inoperative or tilted position; i

Figure 8 is a sectional plan view: along the line8-8 in Figure 5;

Figure 9 is a sectional plan view taken substantially along the line 9-9 in Figure 5;

Figure 10 is a fragmentary plan viewtaken substantially along line 10-40 in Figure 5.

Referring more specifically to the drawings, the stapling machine comprises a substantially U-shaped frame broadly designated atv 10 and which is provided with spaced front andrear upright posts, legs or

arms

11, 12. Both of the arms or

posts

11, 12 are shown as being substantially l-shape'd in plan although this specific construction is not necessary. The I-shape of the front leg 11 is particularly desirable since" this forms ribs 13 taken substantially and 14 thereon for guiding a vertically movable anvil control plate or. element which form's a part of the present invention and will be later described in detail: The frame It) rests upon and is suitably secured to a relatively broad base 15 which, in turn, rests upon a floor or surface indicated at F.

Disposed adjacent thebase 15 is a switch-supporting platform 16 which is supported on a substantially U- shaped framework 17. A. foot pedal or treadle 20 is pivoted as at 21 on the platform 16 and' is normally biased upwardly by any suitable means, such as a compression spring 22. The upper end. of compression spring 22in Figure 1 bears against'the' lower surface of. the"- treadle A solenoid controlled by a first treadle-operated aeeaeee 20 and the lower end thereof bears against a projection 23 on the framework 17. Disposed within the framework 17 is a normally open switch 24 which projects upwardly through the platform and has a spring loaded plunger 26 on its upper end which is normally spaced below the treadle 20. Thus, when the treadle 20 is depressed by an operator, it engages and depresses the plunger 26 to close the normally open switch 24.

The normally open switch 24 is interposed in an electrical circuit to a solenoid coil 27 which circuit includes a pair of

lead wires

30, 31, corresponding ends of which are connected to a plug 32 and adapted to be connected to a suitable source of electrical current, not shown. The other ends of

wires

30, 31 are connected to corresponding sides of the switch 24 and the other side of the switch 24 has a pair of wires or

conductors

33, 34 leading therefrom to opposed ends of the solenoid coil 27. The solenoid coil 27 is supported in a rectangular bracket 35 suitably secured to the rear surface of the rear leg 12 of the U-shaped frame adjacent the upper end thereof.

Solenoid coil 27 surrounds a solenoid plunger 37 which extends downwardly through the lower horizontal portion of the rectangular bracket 35 and is suitably pivotally connected to a transverse bar 40. Although the lower end of the plunger 37 may be pivotally connected directly to the transverse or lateral bar 40, in this instance, the lower portion of the plunger 37 has a transverse slot or opening 41 therein forming a bottom wall 42 whose opposite sides are engaged by compression springs 43,

44. A rod 45 is guided in said bottom wall 42 and its lower end has a clevis 46 therein which is loosely penetrated by a stub shaft or bolt 47 to which the medial portion of the transverse bar 40 is suitably secured, as by welding.

The upper end of the rod 45 has a head 50 thereon against which the upper end of compression spring 43 bears and the lower end of compression spring 44 bears against the clevis 46. Laterally spaced arms of an inverted substantially U-shaped yoke 51 are suitably secured to the lateral or transverse bar 40 and the upper lateral portion of the yoke 51 loosely penetrates and is pivotally connected to the lower end of a clevis 52 on the lower end of a shock absorbing shaft or rod 53 which loosely penetrates a bar 54 which is a part of a stapler actuating lever 58. Thus, the clevis 52 serves to pivotally connect the yoke 51 to the rear end of the stapler actuating lever 58.

The shock absorbing shaft 53 loosely penetrates the bar 54, is surrounded by compression spring 55 and has an enlarged portion or washer 56 secured on the upper end thereof by means of a nut 57. The lower end of compression spring 55 bears against a washer or projection 60 which, in turn, bears against or is formed as a part of the bar 54. The medial portion of the stapler actuating lever 58 has a depending boss 62 thereon which is pivotally mounted, as at 63, between spaced opposed substantially Z-shaped legs 65 of an inverted substantially U-shaped bracket 66.

It will be noted that the upper lateral portion of the bracket 66 is spaced above the actuating lever 58 and is spaced forwardly of the pivot point 63 and has an adjustment screw or abutment 67 mounted therein which is normally engaged by the lever 58 and limits upward movement to the front portion thereof. The lower ends of the substantially Z-shaped legs 65 of bracket 66 extend inwardly and then downwardly and are suitably secured to opposite sides of the rear leg 12 of the main frame 10.

The upper end of said rear leg 12 has a block support 70 fixed thereon on which a block 71 is adjustably secured. In this instance, a dovetailed connection is provided between the block support 70 and the block 71 to permit forward and rearward adjustment of the block 71 relative to the main frame 12. vThe block 71 is secured in adjusted position on the block support 70 by means of the screw 72. The bifurcated upper portion of block 71 has the rear end of an arm 73 of a conventional stapler or fastener-applying element broadly designated at 75 pivotally connected thereto as at 76. The arm 73 of the stapler 75 is of usual hollow construction and serves as a housing for staples, not shown, which staples may be inserted through the rear end of the arm 76 and which are normally urged forwardly by a spring loaded element 80 in a manner well known in the art.

The front end of the arm 73 has a conventional stapler head 81 thereon in which a plunger 02 is mounted for vertical movement, said plunger being provided with a cap 83 and normally being urged upwardly by a com pression spring 84. It will be noted that the cap 83 on the plunger 82 is held against the front portion of actuating lever 58 by means of a tension spring 86, one end of which is connected to the forward portion of the lever 58 and the other end of which is connected to the stapler head 81. The construction heretofore described is similar to that disclosed in said co-pending application and it is with such construction that the present improvements are adapted to be used.

Improved anvil operating structure Pivotally connected by pivotal means 91 to the upper portion of the front leg 11 of the substantially U-shaped main frame 10 is the medial portion of a hollow or substantially channel shaped anvil supporting lever 90. The anvil supporting lever comprises a web portion 92 and

opposed side flanges

93, 94. The

flanges

93, 94 straddle the

ribs

13, 14 on opposite sides of the front leg 11 of the main frame 10 and the upper ends of the

flanges

93, 94 support a suitable clinching anvil 95 therebetween (Figures 5, 6, 7 and 10). It will be noted that while the stapling machine is inactive, the anvil supporting lever 90 is inclined so the anvil 95 is disposed to one side of or forwardly-of the vertical plane of the front portion of the stapler 75. In order to accommodate this angular position of the anvil supporting lever 90, it will be observed in Figures 6 and 7 that the upper portion of the front leg 11 of the main frame 10 is cut away at an angle as at 96.

The front leg 11 of the main frame 10 has a relatively large opening therethrough which is penetrated by the medial portion of a relatively small shaft or follower 101. Opposite ends of the shaft 101 are fixed in the lower portions of the

side flanges

93, 94 of-the anvil supporting lever 90. An anvil controlling element or plate 102 is mounted for vertical sliding movement against the leg 11 and between the

ribs

13, 14 on one side thereof and this control element or plate 102 has a slot 103 formed at an angle therein through which the pin or shaft 101 loosely extends. The slot 103 extends upwardly and for- Wardly at an angle from a point adjacent the 'corresponding rear rib on the front leg 11 of the main frame 10 and its upper front end terminates adjacent the corersponding front rib 14 where the slot 103 communicates with a notch 104 formed in the control plate 102. The control plate 102 has an elongated stem or bar 105 depending therefrom whose lower end extends through a solenoid coil 106 and thus acts in the capacity of a solenoid plunger. 'l he solenoid coil 106 is mounted in a bracket 107 suitably secured to the web portion of the main frame 10. Downward movement of the rod or solenoid plunger 105 is limited by an enlarged portion or collar 110 on the rod or plunger 105 which bears against the upper end of the bracket 107 through which the rod 105 loosely extends, when the solenoid coil 106 is energized. The rod 105 and the control plate 102 are normally urged upwardly by any suitable means such as a tension spring 111 whose lower end is connected to the collar or enlarged portion 110 and whose upper end is suitably connected to the leg 11 of the main frame 10.

It is thus seen that the tension spring 111 normally urges the'control plate or element 102 upwardly so it so that the rear portion of the walls of the slot 103 are in engagement with the shaft 101. Accordingly, the anvil supporting lever 90 normally occupies the inclined or inoperative ,position shown in Figures 1 and 7.. Upon energization of the solenoid coil 106, by means to be later described, the solenoid plunger or rod 105 is pulled downwardly within the coil 106 to thus effect corresponding movement of the control plate 102. In so doing, the walls of the slot 103 serve as cam surfaces and impart movement to the lever 90 in a clockwise direction from the position shown in Figure 1 and Figure 7 to substantially thev position shown in Figure 6. With further downward movement of the control plate 102, the wall defining the notch engages the shaft or follower 101 thus locking the lever 90 in substantially vertical or operative position so the clinching anvil 95 is alined with the lower end of the stapler head 81.

In order to insure that the anvil 95 is accurately positioned upon energization of the coil 106, when the anvil supporting lever 90 reaches the position so that the anvil 95 is properly alined with the stapler head 81, the web portion 92 of the anvil supporting lever 90 engages an adjustable stop or set screw 112 which threadably penetrates the leg 11 of the main frame at a point below the pivot point 91 of the anvil suporting lever 90 and which is held in adjusted position by a lock nut 113.

Now, in order to insure energization of the coil 106, with consequent movement of the anvil into operative position, before the stapler is actuated, the rear portion of the treadle 20 has a suitable spring anchor 115 extending outwardly therefrom to which the lower end of a tension spring 116 is connected. The uper end oftension spring 116 is connected to an upwardly biased actuating arm 117 of a normally open switch 120 suitably supported on the platform 16. Corresponding ends of wires or conductors 121, 122 are connected to one side of the switch 120 and the other ends of the wires 121, 122 are connected to the

respective lead wires

30, 31. The other side of the switch 120 has a pair of

wires

123, 124 leading therefrom whose other ends are connected to opposite ends of the solenoid coil 106.

Assuming the parts normally occupy the position substantially as shown in Figure 1, upon thearticle to be stapled being inserted between the then inoperative anvil and the stapler head 81, the treadle 20 is depressed so the spring 116 imparts downward movement to the switch actuating arm 117 and thereby closes the switch to cause current to flow through the solenoid coil 106. This will cause the anvil supporting lever 90 to move in a clockwise direction in Figures 1 and 7 to the position shown in Figure 6 in the manner heretofore described to accurately position the anvil 95 thereon in operative position or, in other words, in vertical alinement with the stapler head 81. During the course of said downward movement of the pedal 20, the pedal engages and depresses the plunger 26 of switch 24 to subsequently cause current to flow to the solenoid coil 27 and to thereby cause the solenoid plunger 37 to dart upwardly in Figures l and 2. In so doing, the lever 58 moves in a counterclockwise direction in Figure 1 to initially impart downward movement to the stapler sead 81 and to then depress the cap 83 and the plunger 82 to effect a stapling operation.

It will be'noted that upon each successive operation being completed, as the pedal 20 is released, it moves upwardly and first opens the switch 24 to permit the stapler 75 to return to the inoperative position shown in Figure 1 and, thereafter, with further upward movement of the treadle 20, the switch 120 is opened to de-energize the coil 106 so the spring 111 will return the anvil supporting lever 90 to the inoperative position substantially as shown in Figures 1 and 7.

It is thus seen that I have provided'a stapling machine including a frame having a stapler thereon which normally occupies a raised or inoperative position-with a tiltable or pivoted anvil supporting lever thereon which also normally occupies inoperative position so the anvil thereon is positioned to one side of the vertical plane of the head of the stapler. Thus, with a single operative movement of the foot pedal thereof, the anvil is moved into operative position whereupon the stapler moves downwardly and the plunger thereof is then forced down-.

wardly relative to the stapler to cause a staple to be discharged from the stapler and projected through the ele-- ments to be secured together and clinched on the anvil. Further, as the pressure on the foot pedal is released, the head of the stapler initially moves to inoperative position relative to the anvil, whereupon the anvil and its supporting lever swing outwardly to provide sufficient clearance between the anvil and the stapler head to facilitate ready insertion of articles therebetween.

In the drawings and specification there has been set forth a preferred embodiment of the invention and, al-

though specific terms are employed, they are used in a.

generic and descriptive sense only and not for purposes of limitation, the scope of the invention being defined in the claims.

I claim: 7

1. In a fastener-applying apparatus having a frame provided with spaced front and rear uprising legs thereon, a stapler pivotally supported on the upper end of the rear leg and having a stapler head thereon overlying the front leg of said frame, and electrically operablev means for imparting an active downward stroke tosaid stapler head in a stapling operation; the combination therewith of an anvil-supporting lever pivotally mounted on the upper portion of said front leg and having an anvil on the upper end thereof, transversely disposedmeans extending from the lower end of said lever, resilient means normally urging the upper end of said lever and its anvil outwardly of the vertical plane of the stapler head and said front leg, and electrically operable means including a vertically disposed elongated control element mounted for vertical movement on said front leg'and having a cam surface on its upper end in engagement with said transversely disposed means on the lower end of said lever for swinging said anvilsupporting lever into the vertical plane of said stapler head and said front leg prior to said first mentioned electrically operable means imparting an active downward stroke to said stapler head.

2. In a fastener-applying apparatus having a frame provided with front and rear uprising legs thereon, a stapler pivotally supported on the upper end of the rear leg and having a stapler head thereon overlying the front leg of said frame, and electrically operable means adapted to impart an active downward stroke to said stapler headfor a stapling operation; the combination therewith of an anvil supporting lever pivotally mounted on the upper portion of said front leg and having an anvil on the. upper end thereof, transversely disposed means extending from the lower end of said lever, means normally urging the upper end of said' lever and its anvil outwardly of the vertical plane of the stapler head and said front leg, and electrically operable means including a vertically disposed elongated control element mounted for vertical movement on said front leg and having a cam surface on its upper end in engagement with said transversely disposed means on the lower end of said lever for swinging said anvil supporting lever intothe vertical plane of said stapler head and said front leg.

3. In a fastener-applying apparatus having a frame provided with front and rear uprising legs thereon, a stapler pivotally supported on the upper end of the rear leg and having a stapler head thereon overlying the front leg of said frame; the combination therewith of an anvil supporting lever pivotally mounted on the upper portion of said front leg and having an anvil on the upper end thereof, transversely disposed means extending from the lower end. of said lever, means normally urging the upper-end of said lever and its anvil outwardly ofther vertical. plane of the stapler head and said'front leg, and electrically operable means including a vertically disposed elongated control element mounted for vertical movement on said front leg and having a cam surface on its upper end in engagement with said transversely disposed means on the lower end of said lever for swinging said anvil supporting lever into the vertical plane of said stapler head and said front leg.

4. In a fastener-applying apparatus having a: frame provided with front and rear spaced uprising legs thereon, a stapler comprising an arm pivotally mounted on the upper end of said rear leg and having a stapler head on the free front end. thereof spaced above the front leg, means normally urging the stapler upwardly to a predetermined position relative to said front leg, solenoid operated means for imparting downward movement to the stapler head toetfect actuation thereof, and a first normally open switch. interposed in. a circuit to said first solenoid; the combination therewith of a lever pivotally mounted on the. upper portion of said front leg, an anvil fixed on the upper end of said lever, transversely disposed means extending from the lower end of said lever, a vertically disposed'control element mounted for vertical movement on said. front leg and having a cam surface on its. upper end in engagement with said transversely' disposed means on the lower end of said lever,

a solenoid plunger connected to the lower end of said control element and extending downwardly therefrom, a second solenoid coil surrounding the lower portion of said solenoid plunger, a second normally open switch interposed. in a circuit to said second solenoid coil, spring means normally'urgiug said control element. upwardly, a-

foot pedal for closing said first switch to energize the first-named solenoid operated means, said control element being so formed as to cause the upper end of the lever to tilt forwardly out of the vertical plane of the stapler head under the influence of said spring when the second solenoid coil is tie-energized and also being so arranged as to cause the upper end of the lever to move into the vertical plane of said stapler head when said second solenoid. coil is energized, and means operable during the course of movement of said foot pedal, and prior to the closing of said first switch for closing the second switch to thereby cause the upper end of said lever to move into the vertical plane of said stapler head prior to actuation. of said stapler.

5. In a fastener-applying apparatus hraving a. frame provided with front. and rear spaced uprising legs there on, a stapler comprising an arm pivotally mounted on the upper end of said rear leg and having a stapler head on the free front end thereof spaced above the front leg, means normally urging the stapler upwardly to a predetermined position relative to said front leg, solenoid operated means for imparting downward movement to the stapler head to effect actuation thereof and a first normally open switch interposed in a circuit to said first solenoid; the combination therewith of a lever pivotally mounted on the upper portion of said front leg, an anvil fixed on the upper end of said lever, a control element mounted for vertical movement on said front leg and having a cam surface, a shaft loosely penetrating said leg at a point below the pivot point of said lever and having at least one of its ends connected to said lever, said shaft engaging said cam surface, a solenoid plunger connected to said control element and extending downwardly therefrom, a second solenoid coil surrounding the lower portion of said solenoid plunger, a second normally open switch interposed in a circuit to said second solenoid coil, spring means normally urging said control plate upwardly, a foot pedal for closing said first switch to energize the first-named solenoid operated means, said cam surface on the control element being so formed as to cause the upper end of the lever to tilt forwardly out of the vertical plane of the stapler head Imderthe; influence.- ofsaid springwhen. the second sole noid coil is deenergized and also being so arranged. asv to cause the upper end of'the lever to move into the vertical plane of. said stapler head when said second solenoid coil is energized, and means operable during the course of movement of said foot pedal and prior to the closing of said first switch for closing the second switch to thereby cause the upper end-of. said lever to move into the'verticalplane of said stapler head prior to actuation of said stapler.

6. Ina fastener-applying apparatus having a frame provided with front and rear spaced uprising legs thereon, a stapler comprising an arm pivotally mounted on the upper end of said rear leg and having a stapler head. on. the free front end thereof spaced above the front leg,

means normally urging the stapler upwardly to a pre.-

determined position relative to said front leg, a first.

solenoid for imparting downward movement to the stapler. head toeifect actuation thereof and a first normallyopen switch interposed in a. circuit to said solenoid; the com-' bination therewith of a lever pivotally mounted on the:

upper portion of said front leg, an anvil on the upper end of said lever, a control element mounted for vertical movement on said front leg and having an angularly extending slot therethrough, a shaft loosely penetrating said. leg at a point below the pivot point of said lever and. having at least one of its ends connected to said lever, said shaft also loosely penetrating said slot, a solenoid plunger connected to said control element and extending. downwardly therefrom, a second solenoid coil surrounding the lower portion of said solenoid plunger, asecond normally open switch interposed in a circuit to said. second solenoid coil, spring. means normally urging said control element upwardly, a foot pedal for closing said. first switch to energize the first solenoid, said slot in the control element being so formed as to cause the upper end. of the lever to tilt forwardly out of the vettical plane of the stapler head under the influence ofv said spring when the second solenoid coil is de-energized and also being so arranged as to cause the upper end of the lever to move into the vertical plane of said stapler head when said second solenoid coil is energized, and means operable during the course of movement of said foot pedal and prior to the closing of said first switch. for closing the second switch to thereby cause the upper end of said lever to move into the vertical plane of said stapler head prior to actuation of said stapler.

7. In a fastener-applying apparatus having a frame provided with front and rear uprising legs thereon, a fastener applying element supported on the upper end of the rear leg and overlying the front leg of said frame; the combination therewith of an anvil supporting lever pivotally mounted on the upper portion of said front leg and having an anvil on the upper end thereof, transversely disposed means extending from the lower end of said lever, means normally urging the upper end of said lever and its anvil outwardly of the vertical plane of the fastener applying element and said front leg, and electrically operable means including a vertically disposed elongated control element mounted for vertical movement on said front leg and having a cam surface on its upper end in engagement with said transversely disposed means on the lower end of said lever for swinging the lever into the vertical. plane of said fastener applying element and said front leg.

8. In a fastener applying apparatus having a frame provided with front and rear upstanding legs thereon, and a fastener applying element supported on the upper end of the rear leg and overlying the front leg of said frame; the combination therewith of an anvil supporting lever pivotally mounted on the upper portion of said front leg and having an anvil on the upper end thereof, means normally urging the upper end of said lever and its anvil outwardly of the vertical plane of the fastener applying element and said front leg, and electrically operable means including a vertically disposed elongated control element mounted for vertical movement on said front leg, said anvil supporting lever and said control element having overlapping proximal portions thereon, one of said overlapping portions having a cam surface, the other overlapping portion having follower means engageable with said cam surface whereby, upon said electrically operable means being energized, the lever is swung into the vertical plane of said fastener applying element and said front leg.

References Cited in the file of this patent UNITED STATES PATENTS Maynard Apr. 28, 1931 Heller Sept. 13, 1938 Hofiert May 2, 1944 Spiller Apr. 27, 1948 Young Sept. 6, 1949 Sasser Sept. 15, 1953