US2738748A - Toggle lever operating arrangement for a press - Google Patents

Description

March 20, 1956 Filed Jan. 29, 1952 6 Sheets-Sheet l VIII/[IA V INVENTOR: HELmvT H March 20, 1956 H. HE HT 2,738,748

TOGGLE LEVER OPERATING ARRANGEMENT FOR A PRESS Filed Jan. 29, 1952 6 Sheets-Sheet 5 INVENTOR. HELrm/ HECHT March 20, 1956 HECHT 2,738,748

TOGGLE LEVER OPERATING ARRANGEMENT FOR A PRESS Filed Jan. 29. 1952 '6 SheetsSheet 5 IHVEN'TDR: H ELMUT' HEWT March 20, 1956 H. HECHT 2,738,748

TOGGLE LEVER OPERATING ARRANGEMENT FOR A PRESS Filed Jan. 29, 1952 6 Sheets-Sheet 6 IN VENTORZ HELMVT HEeHT particularly 'toja toggle l eve'r an 'resting'of a movable rjrieriiherfaf'c y 7 her through ato'g'gle levierarran'gemem while the drive to move.

position temporarily ir'nm attached to the p'lng'er movable .die in (secreting United S rs? t siriQflf 1,738,748 TOGGLE LEvEizioiiriihTNG FOR A PRESS Hermit: He'cht, Giipl'iiflgeh (Wiimeiiib Germany, assignor to .FirmaMay-Prsseiibau G. in. b. H Schwabis'ch Gmund, Germany A'ppiicaiio'ir names, iifsz, "6815 "12 Claims. c1. 113--3s The present ihye'fifdn relates to presses, and more n'ierit permitting are'd. byfi drive memrn'ember continues it'sfin H In the knownfopcratuigfarrange 'ents for stamping presses it has, not'been possible to bnhg amovas e memibje'r operated by 'a toggle e'ver'sy 1,0313: petefs tandstill while the driving means onnect ed thereto continue For certain press operations lhoweyer, it 'is highly desirable to hold a movableniiiihr inoperative y le. In a stir ping press, for instance. the hdldihgfm mberjwhich clamps down a blank should be at a completestartdstill before, the die seat "the 'fstiarnping tep proper. For mold ng fpresse a' s I ll, fart sting or a ly'a va'ntageous. ention 'to provide a press inde- I It is. the objec of the pres 1 means for arresting a movable ineinb pendently of the movementof a drive It 'is another "object of "the 'p in ast'amping pr'essa resilient connec member and the :to'g'gle lever sy p m'ember, permitting furthe move'tiientof the dr'igve memher after the holding member is arrested in operative position. y I y it is a further object of the vide in a press a resilie" member and a holdingto the machine in the iev'ent t at V V able member is blocked b'y excessively,

it is a still further objejctftif, th provide in a press a eo inect n ber and a holding member, drive member to the holding these members move, butresiliently yields movement of the holding me e blocked, the driving member to continue mov" iii r it i fi tbv' rriding the resilient actidn of the connect 'g' in ns without any further resistance bythe connecting J It is also an object er the present inyen'tion to provide a stamping press in which a anatngrnemee and a plungermember are driven from the 'same drive means and are connected to each other byresilie'ntly yielding connecting meanspermitting the plunger to continue its working stroke aftertheholdin'g member has been arrested inoperative position. v

With these objects in view the present inventionmainly consists in a movable holding member rc ciprocably mounted in the frame of. a stamping press a-leversystem including toggle levers connectingthe movable holding member with a drive triember and resiliently yielding connecting means at aged between the tog' g'le lever system and the drive 'nierfihe'r. A

The resiliently yielding conriectin'g means maybe a piston slidably mounted in 'a'c'ylinder,u ed direction transversal to themoveriieiit er Le drive :niefnber by the for or a spring or by an fifiriifiye-iis'sfifi'id liifil'id in 2,738,748 M, seta, Meet? .5?

the cylinder. In the event that the drive of the press is hydraulically operated, the operating liquid in the cylinder is the same as used for the drivemember.

Preferably the axis of the cylinder of the connecting means is arranged normal to the direction of 'movement of the drive member whereby a rigid connection is formed in a direction of movement of the .drive member, and the resiliently yielding connection is formed for movement of the lever system normal to the direction of movement of the drive member. I y A press according to the present invention may be driven by means of a crank shaft or by means of hydraulically operated cylinder and piston means. In either case the drive member preferably performs a straight movement in the same direction as, or in opposite direction to the movement of a movable member connected to the drive member by lever systems.

Several lever systems and resilient connecting means are provided for large presses exerting high pressure, and such lever systems are preferably arranged symmetrically to .the drive member.

in a stamping press a movable member may be particularly advantageously employed as a holding member for blanks, .While the plunger member may constitute the drive member. The driving means which may be a crank shaft rotated by a-motor, and the plunger may be arranged on the same side or on opposite sides of the plane constituted by the surface of the press table.

The novel features which are considered as characteristic for the invention are set 'forth inwparticuiar in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof; will be best understood from the following descriptionof specific embodiments when read in connection with the acco'mpanying drawings, in which:

Fig. l is a sectional view of a stamping press provided with ahydranlically operated drive member on the line 1-.-1 of Fig. 3; y

Fig. .2 is a sectional view on line 2- -2 in Fig. 3, the toggle lever system illustrated in. Fig. 1 being omitted;

. 'Fig'. 3 is a erossseetional view on line 3 -3 orrtg. 2;

Fig. 4 is a sectional view on line 6+4 of Fig. 3; Fig. 5 is an enlarged partly sectional view of an operatingarrangement as shown in Fig. 1;

Fig. 6 is a view of the operating arrangement shown in Fig. 5 in another position; .7

. Fig. 7 is a sectional view of'a detail on line 7-7 of Fig. 5;

Fig. 8 is a sectional view of a. stamping press driven by a rotating crank shaft on line 8--8 .in Fig. 10;.

Fig. 9 is a sectional view of an enlarged detail taken on line 9-9 in Fig. 10; V

Fig. 10 is a cross-sectional view takenori line Iii-10 inFig.8; Y

Fig. 11 is a partly sectional view of an enlarged detail or Fig; 8;

Fig. 12 is a View similar to Fig. 11 showing a different position of the operating arrangement; and I Fig. 13 is a sectional view of an enlarged detail on line l3-i3 of Fig. ll.

Referi ing now to the drawings. Figs l to 4 show a hydraiilically driven stampingpress aecdrding to" the present invention. A holding member 3 is guided in the sna snng frame n depress guiding means 2 as rod 8, carrying the piston 7, passes through openings at the ends of the cylinder 6 and is secured on one end thereof to the upper part of the supporting frame of the machine, and on the other end to a transversely extending bar 131 which is a part of the press body. The guiding rod 8 is secured on both ends thereof to the supporting frame by means of nuts 9.

The drive member, or drive cylinder 6 is provided with transversal ribs 601, 602 and 603, clearly shown in Fig. 4, which are connected by longitudinally extending ribs 604. The transversal ribs 601, 602 and 603 engaging guiding members 10 which are secured to the supporting frame of the machine can be best seen from Figs. 3 and 4. The transversal rib 601 is provided with forked projecting portions 605 extending substantially normal to the direction of movement of the drive cylinder in a transversal plane. The transversal rib 601 is provided with bores 606 in the forked portions thereof which constitute cylinders in which pistons are reciprocably movably mounted. The axes of these cylinders 606 are parallel to each other and extend in a transversal plane normal to the main axis of the machine and to the direction of movement of the drive member. The cylinders 606 are arranged in two pairs having aligned axes, the axis of each aligned pair being parallel to the axis of the other aligned pair and extending normal to a plane of symmetry passing through the drive member from the front to the rear of the machine.

Each of the four pistons 20 is connected to the holding member 3 by a lever system, the four lever systems being symmetrically arranged, and exactly alike.

Each of these four lever systems comprises a lever 18, pivoted to one of the pistons 20 and actuating a set of toggle levers 11 and 14. The long toggle lever 11 is pivotally connected to a member 16 which is slidably mounted in the holding member 3, and adjustable by nut and bolt means in a direction parallel to the main axis of the machine.

Two short toggle levers 14 are pivotally mounted on each of the shafts 12 which are mounted on the supporting frame of the machine. Two such shafts 12 are provided as can be clearly seen from Fig. 3. The first long toggle lever 11 is pivotally connected to one end of the second short toggle lever 14 by a pin 13 while the other end of the lever 14 is pivoted to lever 18 by a pin 19. Consequently all pivoting axes of the lever system are parallel and extend normal to the direction of movement of the drive member 6 and of the holding member 3.

The construction of the forked portions 605 and the pistons 20 can be best seen from Figs. 5 and 7 when ex- 1 amined in connection with Fig. 3. The forked portions 605 are provided with a plate 28 secured thereto by bolt and nuts and serving as a stop means for the piston 20. A port 32 is provided near the other end of the cylinder 606 through which an operating liquid may be supplied or discharged. The piston 20 is slotted as shown in Fig. 7 whereby forked portions 201 are formed for mount ing the pivoting pin 22 of the lever 18.

The end of the short lever 14 which is pivotally connected to the lever 18 is provided with a projection 25 clearly shown in Figs. 1, 5 and 6 which abuts against an abutment 26 on the supporting frame of the press when the toggle lever 11 and 14 are in almost aligned position.

Referring again to Fig. 2, the drive cylinder 6 is pivotally connected at 61 to levers 63 which engage two-armed toggle levers 53 which are pivoted on the shafts 12. Toggle lever 58 is pivoted by pin 59 to a toggle lever 55. Lever 63 is pivotally mounted between forked portions 607 of the ribs 601 and 602 on pin 61.

As can be seen from Fig. 2, the end of the toggle lever 55 is pivoted to a member 56 which is mounted in the plunger member 53 slidably in the direction of movement thereof and may be adjusted by worm wheel 57 and a worm (not shown).

The toggle lever systems connecting the drive member with the holding member 3 are arranged symmetrically in front of and behind the toggle lever systems connecting the drive member with the plunger member 53, all toggle lever systems being arranged in parallel planes as can be seen from Fig. 3. The shafts 12 provide pivoting points for all three toggle lever systems.

The arrangement operates as follows:

When the drive cylinder 6 moves upwardly the lever 18 urges the toggle levers 11 and 14 from the angular position shown in Fig. 5 to an almost aligned position shown in Fig. 6 so that the holding member 3 is moved downwardly. Simultaneously the lever system 63, 58 and move the plunger member 53 in the same direction.

In the position shown in Fig. 5, lever 18 is in the position AA, and the holding member 3 is in inoperative lifted position. In this position piston 20 is urged to the left by the operating liquid contained in the cylinder 606 to engage the stop means 28. Since the drive member 6 moves normal to the axis of the cylinder 606, the connection between piston 20, and ribs 601 and the forked portion 605 thereof,'respectively, is rigid.

In the beginning of the movement of the drive member the movement of the holding member is comparatively fast in respect to the movement of the plunger member which is caused by the particular arrangement of the respective operating lever systems. After the drive member 6 has moved for a predetermined distance turning the short toggle lever 14 about the shaft 12, the toggle levers 14 and 11 are in an almost aligned position as shown in Fig. 6, corresponding to an operating clamping position of the holding member. When the toggle levers reach this position, the projection 25 of the toggle lever 12 abuts against the stationary abutment means 26. The lever 18 is now in the position B--B, and the toggle levers 14 and 11 and the holding member 3 are blocked. In this position the blank is clamped down by the holding member.

The drive. member continues its movement and the plunger member is actuated by toggle levers 58 and 55 to carry out the stamping operation. While the drive member 6 continues its movement the lever 18 is pivoted about the pin 19 and arrives at the position C-C as shown in Fig. 6 in broken lines. The end of lever 18 which is pivoted to the piston 20, moves along a circle so that the piston 20 moves a distance a in the cylinder 606. Consequently, a free space must be provided between the end of the piston and the bottom of the cylinder, and the distance [2 must be greater than the distance a. The cylinder 606 either contains a compressible fluid or communicates through the port 32 with a container containing a compressible fluid such as compressed air. In this event an operating liquid is contained in the cylinder 606.

During further movement of the drive cylinder 6, the lever 18 turns further about the pivot pin 19 and the piston 20 returns to its initial position due to the action of the compressed fluid on the operating liquid contained in the cylinder 606. Shortly before the piston 20 arrives in the end position defined by the stop means 28 the lever 18 is in the position D-D and the movement of the drive member is terminated. When the drive member 6 moves downwardly the procedure is reversed, and first the plunger member 53 is moved upwardly while the piston 20 performs its reciprocating movement, whereupon the toggle lever system 1114 is actuated to lift the holding member 3.

Figs. 8 to 13 illustrate a press according to the present invention in which the plunger member is driven by crank means. 011 the upper part of the supporting frame of the press 17 a motor 71 is mounted driving a shaft 73 by a belt 72 and a pulley 74. Pinions 75 are arranged at the ends of shaft 73. Two gears 76 each meshing with one of the pinions 75 are fixedly connected to pinions 77 which mesh with the main gears 78 arranged at the -ends of the crank shaft 89. -The"driving means 71 to 77 are schematically indicated in broken linesjinFig. 8.

Crank shaft 79, rotatably mounted on the supporting frame of the press, drives a connecting rod .82 which is pivoted to the plunger 83. Fig. 8 shows the crank in the upper dead center position, while for the sake of clarity the crank'is shown in Fig. in a horizontal position. The holding member 85 is provided with a wide passage permitting the plunger member and the die to pass therethrough. The plunger member 83 is guided on' guiding means 84 inside the'holding member, while the holding member 85 is slidably guided onguiding means 86 on the supporting frame of the machine. The holding member 85 is actuated by the plunger member 83 through four symmetrically arranged lever systems. Since the four lever systems are identical, only one will be described hereafter.

A shaft87, rotatably mounted in the supporting frame of the press, is connected on one hand with the plunger member by means of two pivotedlevers 88 and '89, and on the other hand with the holding'member 85'by means of a pair of toggle levers 90 and 91. 'On each shaft 87 two such lever systems are arranged. The plunger member 83 is provided on its upper part with two forked portions 92. A transversal bore 93 passes through the'entire width of the plunger member ending on both sides thereof in forked end portions 92, as clearly shown in Figs. 9 and 11. Two pistons 94 are coaxially arranged in the bore 93, and outwardly urged by a spring 95. Fig. 13 shows the construction'of the pistons 94 in greater detail. Each piston 94 is provided at the outer end thereof with a forked portion 96 abutting in the extreme outer position of the piston 94 against stops 97 which are secured to forked portion 92 of the plunger member 83. In the interior of the bore 93 thespring 95 is arranged and urges the pistons 94 towards the stops 97. Since the bore 93 constitutes a cylinder for the pistons 94, a-passage 104 clearly shown in-Fig. 11, is provided to-permit air to enter and leave the interior of the cylinder 93. On each piston 94 the lever'89 is pivoted on a pin 98 which is.

mounted in the forked portion 96. A pin 9 9 connects the lever 89 with the lever 88. Lever 88 is fixedly mounted on the shaft 87. One end ofjlever 88 is provided with an abutting portion 100 which abuts against abutment means 101 on the supporting frame of the press after The operating arrangement according to the embodiment shown in Figs. 8 to 10 operates as follows:

In Fig. 11 the plunger member 83 and the holding member 85 are assumed to be in their uppermost position. In such position the lever 89 is in the position A- -A and the piston 94 is urged by spring 95 to its outermost position abutting on the stop means 97. When the plunger member 83 is moved downwardly within the holding member 85 along the guide means 84, the lever 89 turns the lever 83 which is pivoted thereto abouttheaxisof the stationary shaft 87, turning shaft; 87 fora predetermined angle. Thereby the short lever 90 which is fixedly connected to the shaft 87 is turned through the same angle so that the first toggle lever 91 and the. second toggle lever 90, 88 are pivoted from an angular position towards an aligned position causing downward movement of the holding member 85 since point 103 is farther spaced from shaft 87 when the toggle levers aresubstantially aligned. When the toggle levers are in almost aligned-position the abutting portion 100 of the lever 88 'engages the abutment means 101 on the machine frame in the position B--B of "action of spring for a distancea, whileduring further movement of the plunger member the pistons 94 move again outwardly until they engage the respective stop means '97. In contrast to the embodiment shown in Figs. 1 to 7, the drive memberof theembodiment shown in'Figs. 8 to 13, whichis constituted by the plunger member, moves in the same direction as the holding memher.

In the embodiment illustrated in Figs, 8 to 13 onespring 95 is provided for two oppositely arranged pistons 94. Even if the cylinders 96 are;supplied"with an operative liquid under pressure and pistons 94are operated hydraulically, a spring may be provided in each cylinder to urge the piston-outwardly inthe event that a disturbance in the supply ofoperating liquid occurs. In the embodiment shown in Figs. 1 to 6 such spring may be provided in each cylinder. I I

It willbe understood that each-of the elements de scribed-above, or two or more together, may also find a useful application in other types of operating lever arrangements diiiering from the types described above.

While the invention has been illustrated and described as embodied in an operating toggle lever arrangement for a stamping presspermitting movement of the plunger member while the holding member is arrested, it is not intended'to be-limited to the details shown, since various modifications and structural changes may be made without departing an any way from the spirit of the present invention. V I

Withoutfurther analysis, the foregoing will so fully reveal the gist of the-present; invention'that others can.

by. applyingcurrent knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention, and therefore, such adaptations should and are intended to becomprehended within the meaning and range of equivalence of the following claims. What is;claimed as new-and desired to be secured by-Letters Patent is: I

1. In an apparatus'of the type described, incombination, a supporting frame; a movable member re'ciprocably mounted in said supporting frame; aiirst toggle lever pivotally connected atone 'endthereof *to sai'd movable member; a second toggle lever-pivotally mounted on said supporting frame turnable about a stationary axis, said second toggle layer being :pivotally connected at a point spaced fromsaid stationary axis to the other end of said first toggle lever, said first and second toggle levers being turnable relative to each other between a first position in which said one end of said first toggle lever is spaced from said stationary axis of said second toggle lever a shorter distance, and a second position in which said one end of said first toggle lever isfspaced-from said stationary axis a greater distance; a ydrive member reciprocably mounted in said; supporting frame movable in a plane extefidihgnormal to thepivoting axes of said toggle levers; a third lever pivotally connected at one end thereof to said second'toggle lever ata pointspaced from said stationary axis and being operative to rotate said second toggle lever about said stationary axis; resiliently yielding eonneeting means mounted onsaid drive member and pivotally connecting the same with the other end of said third lever so that movement of said drive member moves said first and said second toggle levers from said first position to said second position; and abutment means fixedly seeured to saidsu-pporting frameand engaging andholding one of said toggle levers when said toggle levers are in said second position so that further movement of said drive member requires and effects yielding of said connecting means.

2. In an apparatus of the type described, in combination, a supporting frame; a movable member reciprocably mounted in said supporting frame; a first toggle lever pivotally connected at one end thereof to said movable member; a second toggle lever pivotally mounted on said supporting frame turnable about a stationary axis, said second toggle lever being pivotally connected at a point spaced from said stationary axis to the other end of said first toggle lever, said first and second toggle levers being turnable relative to each other between a first position in which said one end of said first toggle lever is spaced from said stationary axis of said second toggle lever a shorter distance, and a second position in which said one end of said first toggle lever is spaced from said stationary axis a greater distance; a drive member reciprocably mounted in said supporting frame movable in a plane extending normal to the pivoting axes of said toggle levers;

a third lever pivotally connected at one end thereof to said second toggle lever at-a point spaced from said stationary axis and being operative to rotate said second toggle lever about said stationary axis; connecting means slidably mounted on said drive member and pivotally connecting the same with the other end of said third lever so that movement of said drive member moves said first and said second toggle levers from said first position to said second position; resilient means urging said connecting means in one direction; and abutment means fixedly secured to said supporting frame and engaging and holding one of said toggle levers when said toggle levers are in said second position so that further movement of said drive member requires and effects yielding of said connecting means.

3. In an apparatus of the type described, in combination, a supporting frame; a movable member reciprocably mounted in said supporting frame; a first toggle lever pivotally connected at one end thereof tosaid movable member; a second toggle lever pivotally mounted on said supporting frame turnable about a stationary axis, said second toggle lever being pivotally connected at a point spaced from said stationary axis to the other end of said first toggle lever, said first and second toggle levers being turnable relative to each other between a first position in which said one end of said first toggle lever is spaced from said stationary axis of said second toggle lever a shorter distance, and a second position in which said one end of said first toggle lever is spaced from said stationary axis a greater distance; a drive member reciprocably mounted in said supporting frame movable in a plane extending normal to the pivoting axes of said toggle levers; a third lever pivotally connected at one end thereof to said second toggle lever at a point spaced from said stationary axis and being operative to rotate said second toggle lever about said stationary axis; connecting means slidably mounted on said drive member and pivotally connecting the same with the other end of said third lever so that movement of said drive member moves said first and said second toggle levers from said first position to said second position; spring means urging said connecting means in one direction; and abutment means fixedly secured to said supporting frame and engaging and holding one of said toggle levers when said toggle levers are in said second position so that further movement of said drive member requires and eifects yielding of said connecting means.

4. In an apparatus of the type described, in combination, a supporting frame; a movable member reciprocably mounted in said supporting frame; a first toggle lever pivotally connected at one end thereof to said movable member; a second toggle lever pivotally mounted on said supporting frame turnable about a stationary axis, said second toggle lever being pivotally connected at a point spaced from said stationary axis to the other end of said first toggle lever, said first and second toggle levers being turnable relative to each other between a first position in which said one end of said first toggle lever is spaced from said stationary axis of said second toggle lever a shorter distance, and a second position in which said one end of said first toggle lever is spaced from said stationary axis a greater distance; a drive member reciprocably mounted in said supporting frame movable in a plane extending normal to the pivoting axes of said toggle levers; a third lever pivotally connected at one end thereof to said second toggle lever at a point spaced from said stationary axis and being operative to rotate said second toggle lever about said stationary axis; a cylinder fixedly mounted on said drive member; a piston reciprocably mounted in said cylinder and ivotally connected with the other end of said third lever so that movement of said drive member moves said first and second toggle levers from said first position to said second position; a container communicating with said cylinder so that a compressed fiuid contained in said container urges said piston in one direction; and abutment means fixedly secured to said supporting frame and engaging and holding one of said toggle levers when said toggle levers are in said second position so that further movement of said drive member requires and effects yielding of said piston.

5. In a press, in combination, a supporting frame; a movable blank holding member reciprocably mounted in said supporting frame; a first toggle lever pivotally connected at one end thereof to said movable blank holding member; a second toggle lever pivotally mounted intermediate its ends on said supporting frame turnable about a stationary axis, one end of said second toggle lever being pivotally connected to the other end of said first toggle lever, said first and second toggle levers being turnable relative to each other between a first position in which said one end of said first toggle lever is spaced from said stationary axis of said second toggle lever a shorter distance, and a second position in which said one end of said first toggle lever is spaced from said stationary axis a greater distance; a hydraulically operated drive member reciprocably mounted in said supporting frame movable in a plane extending normal to the pivoting axes of said toggle levers; a third lever pivotally connected at one end thereof to the other end of said second toggle lever and operative to rotate said second toggle lever about said stationary axis; a cylinder fixedly mounted on said drive member; a piston reciprocably mounted in said cylinder and pivotally connected with the other end of said third lever so that movement of said drive member moves said first and said second toggle levers from said first position to said second position; a container communicating with said cylinder so that a compressed fluid contained in said container urges a portion of said operating liquid contained in said cylinder and thereby said piston in one direction; and abutment means fixedly secured to said supporting frame and blocking said movable member and said toggle levers when said toggle levers are in said second position so that further movement of said drive member requires and efiects yielding of said piston.

6. In an apparatus of the type described, in combination, a supporting frame; a movable member reciprocably mounted in said supporting frame; a first toggle lever pivotally connected at one end thereof to said movable member; a second toggle lever pivotally mounted on said supporting frame turnable about a stationary axis, said second toggle lever being pivotally connected at a point spaced from said stationary axis to the other end of said first toggle lever, said first and second toggle levers being turnable relative to each other between a first position in which said one end of said first toggle lever is spaced from said stationary axis of said second toggle lever a shorter distance, and a second position in which said one V end of said first toggle lever is spaced from said stationary axis a greater distance; a drive member reciprocably mounted "in said supportingframe movable in a plane extending'normal 'to the pivoting axes of said toggle levers; a thirdlever'pivotally connected'at one'end thereof to said'second toggle lever at a point spaced from said stationary'axis'and being operative to rotate said second toggle lever'about said stationary axis; a cylinder mounted on saiddrive memberand having an axis normal to said dir'ectiomofmovement of said holding member and to said pivotingyaxes of said toggle lever means; a piston reciprocably mounted insaid cylinder and pivotally connected. with'theother end'of said third lever so that said drive member, when moving, pivots said first and said'second toggle levers from said'first position to'said second position while said piston remains immovably in saidcylinder; abutment means fixedly secured to said supporting'frame and blocking movement of said toggle lever meansand of said holding member when said toggle-lever means are in said second position so that further movementof'said drive member effects movement of-said pistonin'said cylinder; resilient means urging said piston andsaid third lever toward said abutment means; and stop; means on one end of said cylinder holding said piston in an-endposition against the action of said resilient means.

7. In an apparatus of the type described, in combination; a supporting frame; a movable member reciprocably mounted-in said supporting frame; a first toggle lever pivotally-'connectedat' one endthereof to saidmovable member; a second toggle lever pivotally mounted on said supportingframe turnable about a stationary axis, said second toggle lever being pivotally connected at a point spaced fromi said? stationary axis to the other end of said first toggle lever, said. first and second toggle levers being turnable relative to each other between a first position in which said one endof saidfirst. toggle lever. isspaced from said stationary axisof saidsecond toggle. lever: a shorter distance, and-a second .position in which. said one end ofsaid firsttogglelever is. spaced :from saidstationary axis a greater distance; a drive member reciprocably mounted in said supporting frame movable in a plane extending normal to the pivoting axes of said toggle levers; a third lever pivotally connected at one end thereof to said second toggle lever at a point spaced from said stationary axis and being operative to rotate said second toggle lever about said stationary axis; a cylinder mounted on said drive member and having an axis normal to said direction of movement of said holding member and to said pivoting axes of said toggle levers; a piston reciprocably mounted in said cylinder and pivotally connected with the other end of said third lever so that said drive member, when moving pivots said first and said second toggle levers from said first position to said second position while said piston remains imrnovably in said cylinder; abutment means fixedly secured to said supporting frame and engaging said toggle levers blocking further movement of the same and of said holding member when said toggle lever means are in said second position, said one end of said third lever being located forwardly in the direction of movement in respect to the other end thereof when said abutment means engages said toggle levers so that further movement of said drive member effects reciprocation of said piston in said cylinder; resilient means urging said piston and said third lever toward said abutment means; and stop means on one end of said cylinder holding said piston in an end position against the action of said resilient means.

8. In a press, in combination, a supporting frame; a reciprocable blank holding member slidably guided in said supporting frame movable in one direction; a first toggle lever connected at one end thereof to said blank holding member pivotable about an axis normal to the direction of movement of said blank holding member; a second toggle lever mounted at one end thereof on said supporting frame pivotable about a stationary axis parallel to said axis, the other end of said second toggle lever being pivoted toathe; otherend; of said: first toggle lever forpivotal movement-about an axis parallel tosaidnaxes,v said first and 'secondtoggle: levers being turnable relative to each. other between: 1 a. first position in which said, i one end of said first toggle-lever is spaced. from said stationaryaxis of saidsecondrtoggl'e; lever a shorter distance and a secondpositionin. which said one end of said first,

toggle lever is spacedqfrom said stationary axis a greater distance; a thirdlever; pivotally connected at one end thereof to said other end of said second toggle lever and being operative to:rotate said second toggle lever about' said. stationary axis; a drive member slidably mounted in said. supporting frame reciprocably-movable in said'direction of movement of saitlholding member; a cylinder mounted on saiddrivemember and having an axis normal to said direction'of movement of saidholding member and. to said-pivoting; axes of said toggle levers; a piston reciprocably mountedin said cylinder and pivotally connected with the-other end of said third lever so thatsaid drive member, when moving pivots said-first and said second=toggle levers from said first position to said second position. while said;piston remains immovably in said cylinder;abutment,means fixedly secured to said supporting frame andsengagingsaid toggle levers blocking-further: movement of thesame and of said holding member. whensaidtoggle. lever means are insaid second position, saidone endv of said third lever being located forwardly in the. direction of movement; in respect to the other endthereof'wlren said abutmentmeans engages said toggle levers so that'further movement ofsaid drive member: effectsreciprocation of: said piston in said cylinder; resilient meansurging. said piston and said third lever toward-saidabutment means;and stop means on oneend of: said cylinder; holding. said piston in an end position against the action of said resilient means.

9;. In an apparatus ofthe. type, described, in combination; a. supporting'framq'a movable :member reciprocably mounted'in said; supporting frame; a first toggle lever pivotally connected at one end thereof to said movable member; a second toggle lever pivotally mounted on said supporting frame turnable about a stationary axis, said second toggle lever being pivotally connected at a point spaced from said stationary axis to the other end of said first toggle lever, said first and second toggle levers being turnable relative to each other between a first position in which said one end of said first toggle lever is spaced from said stationary axis of said second toggle lever a shorter distance, and a second position in which said one end of said first toggle lever is spaced from said stationary axis a greater distance; a drive member rcciprocably mounted in said supporting frame movable in a plane extending normal to the pivoting axes of said toggle levers; a third lever pivotally connected at one end thereof to said second toggle lever at a point spaced from said stationary axis and bein operative to rotate said second toggle lever about said stationary axis; resiliently yielding connecting means mounted on said drive member and connecting the same with the other end of said third lever so that movement of said drive member moves said first and second toggle levers from said first position to said second position; and abutment means blocking turning of said toggle levers relative to each other beyond said second position so that further movement of said drive member requires and effects yielding of said connecting means.

10. An operating arrangement as claimed in claim 1 and including another first toggle lever; another second toggle lever; another third lever; another connecting means; and another abutment means, all cooperating in the same manner as the corresponding elements claimed in claim 1 and arranged symmetrically to the same with respect to the plane of symmetry of said movable member extending in the direction of movement thereof.

11. An operating arrangement as claimed in claim 7 and including another first toggle lever; another second toggle lever; another third lever; another piston reciprocably mounted in said cylinder; and another stop means on the other end of said cylinder, all cooperating in the same manner as the corresponding elements claimed in claim 7 and arranged symmetrically to the same with respect to a plane of symmetry of said holding member extending in the direction of movement thereof, said resilient means being arranged in said cylinder between said piston and said other piston urging said two pistons apart.

12. In a press, in combination, a supporting frame; a reciprocable holding member slidably guided in said supporting frame movable in one direction and in opera tive position adapted to clamp down a workpiece; two parallel shafts mounted in said supporting frame and extending normal to the direction of movement of said holding member on either side of the same; four first toggle levers, each connected at one end thereof to said holding member pivotally about an axis extending parallel to said shafts; two pairs of second toggle levers, each pair of second toggle levers pivotally mounted intermediate the ends thereof on one of said parallel shafts, one end of each of said second toggle levers and the other end of each of said first toggle levers being connected pivotally about an axis extending parallel to said axis, each set of associated first and second toggle levers being turnable relative to each other between a first position in which said one end of said first toggle lever is spaced from said stationary axis of said second toggle lever a shorter distance, and a second position in which said one end of said first toggle lever is spaced from said stationary axis a greater distance; a drive member slidably mounted in said supporting frame reciprocable in said direction of movement of said blank holding memher, two of said first and second toggle levers being located on one side of said drive member, and the other two of said first and second toggle levers being located on the other side of the same; four third levers, each third lever pivotally connected at one end thereof to the other end of one of said second levers and being operative to rotate the same about the associated shaft; four cylinders mounted on said drive member, two of said cylinders being located on each side of said drive member, each of said cylinders having an axis normal to said direction of movement of said holding member and to said pivoting axes of said levers; four pistons, each piston reciprocably mounted in one of said cylinders and pivotally connected with the other end of one of said third levers so that said drive member, when moving, pivots said first and second toggle levers from said first position to said second position while said pistons remain immovably in said cylinders; four abutment means, each abutment means fixedly secured to said supporting frame and engaging one of said sets of associated first and second toggle levers blocking further movement of the same and of said holding member when said toggle levers are in said second position, said one end of each of said third levers being located forwardly in the direction of movement in respect to the other end thereof when said abutment means engage said toggle levers so that further movement of said drive member efiects movement of said pistons in said cylinders; resilient means located in each of said cylinders and urging the respective piston and the third lever associated therewith towards the associated abutment means; and stop means on one end of each of said cylinders holding the piston associated with the same in an end position against the action of the resilient means associated therewith.

References Cited in the file of this patent UNITED STATES PATENTS 1,796,786 Hatch Mar. 17, 1931 1,993,839 Hatch et al. Mar. 12, 1935 2,105,053 Patrick Jan. 11, 1938 2,224,968 Klocke Dec. 17, 1940

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