US3400924A - Clamping device - Google Patents

Description

Sept. l0, 1968 F. ARNOLD ETAL CLAMPING DEVICE 2 Sheets-Sheet 1 Filed April 6 1965 Stk vw www N Y m E M sept. 1o, 196s F. ARNOLD ET AL CLAMPING DEVICE 2 Sheets-Sheet 2 Filed April 6, 1965 United States Patent O 45,6 15 Claims. (Cl. 269-228) ABSTRACT F THE DISCLOSURE A clamping device having a fixed and a movable jaw, the movable jaw being actuated and moved by a rotatable spindle, the spindle being connected to a handcrank and being driven through an overload release clutch. The mov- `able jaw is moved into engagement with the workpiece by simultaneous rotation of the handcrank and the spindle. Upon engagement of the workpiece by the movable jaw, the overload clutch releases whereby further rotation of the `handcrank causes a pushrod coaxially mounted within the spindle to axially extend. The pushrod has a pressure member mounted on the end thereof, which member coacts with a pair of toggle mechanisms so as. to exert a high clamping pressure onto the movable jaw. Each toggle mechanism comprises a pair of links and three cylindrical pressure rollers, each of the links being provided with partial cylindrical recesses on opposite ends thereof for receiving the pressure members therein. The links and the rollers have a large axial length whereby large bearing areas are provided between the respective members of the toggle mechanism to permit transfer therethrough oflarge clamping pressures. The toggle mechanismsl are mounted within a U-shaped frame member comprising the movable jaw whereby the jaw member can withstand the large clamping pressures applied thereto.

. This invention relates to a clamping device for achieving high clamping pressures. More particularly, the present invention relates to a clamping device which is adapted to chuck workpieces and which can be usedas a machine vise. i

More specifically, the present invention relates to a clamping device wherein ,two opposite pairs of toggle means are arranged between an abutment and a slide which carries the clamping jaw, while a movable pressure element for forcing the two pairs of toggle means apart and hence for stretching said pairs is provided between said pairs.

-In a known device of the aforesaid type the pairs of toggle means consist of laminar members, while all toggle links are formed in a usual manner Aby hinge bolts extending through said laminar members. Since only relatively small pressures can be `achieved by toggle means of this type, this known structure is `unsuited for machine vises wherein clamping pressures of at least 4 tons must be achieved. Besides, saidpreviously known toggle means are subject to considerable wear.

The problem underlying the present inventionis to provide a clampingdevice provided with pairs of toggle means by which it is possible to achieve very highclamping pressures and which are virtually not subject to wear. Furthermore, the toggle lever system shall have a simple structure and it shall be easy to manufacture; in particular, it shall be of small dimension so as to occupy a minimum of space in a machine vise or the like.

This problem is solved substantially in that each pair of toggle means `embodying the present invention consists of three press rollers and two support levers which 3,400,924 Patented sept. 1o, 196s ICC are positioned between said rollers and which are supported on said rollers by partial cylindrical bearing surfaces of said levers. Furthermore, substantially semicylindrical recesses which receive said two rollers are provided in said slide and in said abutment. Since these elements of the pairs of toggle means are very compact and sturdy and since they have very large pressure surfaces, it is possible to achieve very high clamping pressures by such pairs of toggle means. All components of these pairs of toggle means as well as the pressure element are made advantageously of hardened steel so thatalso in view of the presence of large pressure surfaces-any wear is practically out of the question.

The pairs of toggle means in this novel structure can be disposed in as small spaces as possibile and they can be advantageously mounted for free displacement between two horizontal parallel bearing plates which are integral with said abutment and which together forma U-prole piece.

Further details and advantages of the clampingdevice embodying the present invention will become apparent from the following detailed description of an exemplary embodiment in connection with the appended drawings in which:

FIG. 1 is a side elevation of a machine vise;

FIG. 2 is the corresponding top plan view partially in section taken along line II-II of FIG. l;

FIG. 3 is a diagrammatic illustration of the slide of said screw vise including the toggle lever system with parts broken away;

FIG. 4 is an enlarged section of one component of the system of FIG. 2.

Referring now to the drawings, 1 represents the substructure of a machine vise, 2 represents the immovable clamping jaw, and 3 represents the movable clamping jaw secured to a slide 4. To the substructure 1 is connected a spindle nut 5 which is secured to the structure 1 by means of a bolt 6 inserted therethrough and which can be arranged in different positions on the substructure 1 in order to achieve diterent stretch widths a. A hollow quick acting spindle 7 which can be rotated bya crank handle 8 and which is connected to an abutment 9 is screwable in said spindle nut 5. As is described hereinafter, said crank handle 8 is designed so that not only the slide 4 carrying the jaw 3 can be moved by way of the quick acting spindle `7 in the clamping direction A toward the workpiece, but also the desired high clamping pressure can be achieved by way of two pairs of toggle means by displacing a push rod 10 in the direction A when said crank handle 8 is nfurther rotated. As shown in the drawing and more particularly in FIG. 3, each pair of toggle means comprises three cylindrical press rollers v11, 12 and 13 and two support levers 15, 16 which are positioned between said rollers and which are supported on said rollers by partial cylindrical bearing surfaces 14 on said levers. The roller 12 constitutes an intermediate cylindrical roller member of the toggle linkage, while the other two rollers 11 and 13 constitute end partial cylindrical bearing members. Substantially semi-cylindrical recesses which receive the rollers 11i and 13 are provided in said slide 4 and in said abutment 9.

As is apparent from the drawings, the support levers have a thickness s which is approximately equal to the diameter d of the press rollers.

In this manner, between the rollers 11-13 and the support levers 15, 16 are formed relatively large, nearly semi-cylindrical pressure surfaces 14 extending over the width h. This permits the achievement of very high pressing forces by the pairs of toggle means, between which there is arranged a pressure element 18 which is secured to the offset end 10a of the pushrod 10 by means of a pin 19. All members 11-13, 15, 16 of the pairs of toggle linkages as well as the pressure member 18 are advantageously made of hardened steel in a distortionless manner due to the simple, compact structure of these members. Only a sliding friction occurs between the aforesaid hardened members when the pairs of toggle linkages are forced apart by moving the pressure element 18 in the direction A, the hardened rollers 11 and 13 being pressed into the softer material of slide 4 and abutment 9 so that said rollers 11 and 13 are securely held and cannot rotate. As is apparent from the drawing, the clearance existing between the push rod and the bore 20 of the hollow spindle 7 as well a-s the bore 21 of the abutment 9, respectively, permits free motion of the pressure element 18 inclusive of the push rod 10 relative to the abutment 9 transversely of the longitudinal direction of the push rod 10-that is to say, in the direction B. This arrangement has the advantage that the pairs of toggle linkages are always in uniform engagement with the pressure element and that, respectively, the pressure element can freely adjust itself when said element is displaced in the direction A so that invariably equally great forces are created between said element and the two pairs of toggle linkages. Thus, due to the fact that said pressure element is mounted for free movement in the direction B, it is possible to avoid any one-sided, unequal forces which would otherwise come into being due to unavoidable dissimilar manufacture and arrangement of both pairs of toggle linkages if said pressure element is immovably mounted.

It will be apparent that said pressure element 18 can either act indirectly upon the pairs of toggle linkages or, advantageously, directly upon the press rollers 12. Said pressure element 18 has convex pressure surfaces 18a Which are suitably cylindrically shaped. Due to said con- Vex cylindrical pressure surfaces cooperating with the rollers 12, it is pos-sible to achieve the force required for displacing the pressure element 18 when the latter is displaced in the direction A-and hence also the torque to be exerted by the crank handle S--which force remains nearly unchanged despite the increasing toggle lever pressure.

Furthermore, as is apparent from the drawing and in particular from FIG. 3, the press rollers 11-13, the support levers 15, 16 and the pressure element 18 have the same height h, and all of these elements are mounted for free movement between two parallel, horizontal bearing plates 22 and 23. These two bearing plates 22 and 23 are advantageously formed integral with the abutment 9 and together form a U-prole piece. Thus, the legs of this U-profile piece constitute the two bearing plates 22, 23 for the pairs of toggle linkages and the pressure element 18, while the web or ridge of this U-prole piece constitutes the abutment 9. This abutment is subjected to considerable bending stress due to the very high pressure forces exerted by the pairs of toggle linkages. Yet deflection or bending of said abutment 9 is prevented by the long legs 22, 23 of said U-prole piece.

As is apparent from FIGS. 2 and 3, in the slide 4 is arranged a stop 24 which is rotatable about a vertical axis and which has two (or more) vertical stop faces at 25 for the push rod end 10a. In the drawing, the clamping device and in particular the `toggle linkage system is represented in the released or expanded condition where a spacing b exists between the end 10a and the set stop face 25 so that the push rod 10 can only be moved a distance b in the direction A. Accordingly, the stop faces 25, 26 permit selection of different clamping pressures. As is shown in FIG. 3, the upper side of slide 4 includes an indicating scale 27 for adjusting the clamping pressure, Isaid scale being concentrically disposed relative to the rotatable stop 24. As is `apparent from FIG. 2, a detent device (ball catch 28, compression spring 29) for arresting the stop 24 in various stop positions is provided between theA slide 4 and the rotatable stop 24.

As is apparent from FIGS. 3 and lfthe U-prole .piece 4 9, 22, 23 with its upper side 38 and the two side surfaces 31, 32 is mounted in the slide 4, and with its underside 33 it is mounted on the upper side 34 of the substructure 1, for longitudinal displacement and guidance in the direction A.

FIG. 2 shows stops 35 for the abutment 9, which are for limiting the displacement of said abutment in the slide 4 iu the clamping direction A. Furthermore, compression springs 36 are arranged between said stops and the abutment. In the embodiment shown, these springs 36 which are formed as cup or disk springs are arranged on bolts 37 which are located in the abutment 9 and engage with the stops 35. The cup springs 36 are effective to constantly urge the abutment 9 in the direction A, in consequence of which the pairs of toggle linkages subjected to this pressure remain movable for free play and are constantly pressed with the rollers 12 against the pressure element 18.

It will be apparent from the drawings that the quick acting spindle 7 is rotatably mounted at 38 with one end thereof on the abutment 9. In this spindle is arranged a compression spring 39 which has one end thereof bearing against the spindle at 40, and has the other end thereof bearing against the push rod 10 at 41. Under the'force of this spring, the spindle end 38 is pressed against one side of the abutment 9, while the transverse face 42 of the pressure element 18 is pressed against the other side of the abutment 9.

For the drive of the above described clamping device a driving spindle 43 is provided which is rotatable by the crank handle 8 and the end 43a of which is rotatably mounted on the push rod 10. This driving spindle 43 is screwable in a nut 44 which is securely connected to the hollow spindle 7 by means of, e.g., pins 45. A torque coupling or clutch is provided between the nut 44 and the driving spindle 43. By way of example, the torque coupling can consist of a coupling member 46 which is slidable on but rotatable with the spindle end 43a and which has wedgelike ribs 48 which engage in corresponding depressions in the nut 44 under the pressure of the cup springs 47.

The driving spindle 43 can be securely connected to a sleeve 49 rotatably mounted on the hollow spindle 7 so that the driving spindle 43 can be rotated not only by the crank handle 8 but also manually by means of the sleeve 49.

In order to ensure an unconstrained transmission of the pressure forces exerted by the driving spindle 43 in the direction A to the push rod 10, the end 43a of the driving spindle is advantageously supported by means of a bearing ball 50 and an axial ball bearing 51 on the end 52 of tht push rod 10, while also a bearing plate 53 is interposed between the ball 50- and the bearing 51.

The vmode of operation of this drive is as follows:

Upon rotation of the crank handle 8, the nut 44 and hence the hollow spindle 7 are rotated by the driving spindle-43 via-the coupling 46-48. Due to thethreaded connection between the spindle 7 and the xednut 5, the hollow spindle 7, the abutment 9, the pairs of toggle linkages and the slide 4 (in the condition of the individual members as shown in FIG. 2) are moved in the `direction A whereby the jaw 3 comes into engagement with the workpiece. In this position, spindle 7 is restrained from further axial movement. Thus, upon further rotation of the crank handle 8, the coupling member 46 will be released whereby the spindle 43 will be movedin the direction A relative to the nut 44. As a result, the push rod 10 will be moved in the direction A so that the pairs 15, 16 of toggle levers will be forced apart by the pressure element 18 causing a small displacement of the slide 4 in the direction A so that the clamping pressure will be considerably increased.

A reversal of this order of succession of these movement steps will take place when the crank handle 8 is turned backwardly, in consequence of which the moved members will be returnedinto the represented starting or initial position under the pressure of the springs 36 and 39.

The present invention is not limited to the illustrative embodiment of a machine vise as is described and represente-d herein but is applicable to clamping devices of all types.

What is claimed and desired to be secured by Letters Patent is:

1. A clamping device for exerting high clamping pressures on a workpiece, said device comprising:

a pair of clamping members adapted to receive a workpiece therebetween, and frame means mounting said pair of clamping members for relative movement therebetween;

drive means connected to one of said clamping members for movement relative to the other said clamping member, said drive members comprising an abutment member and a slide, toggle means interconnecting said abutment member and said slide for causing said relative movement, said slide being iixedly connected to said one clamping member;

. said toggle means comprising a pair of toggle mechanisms, each of which comprises a pair of links having partial cylindrical recesses in each end thereof, a first partial cylindrical bearing member being received in the recess in one end of one of said links and being connected to said abutment member, a second partial cylindrical bearing member being received in the recess in one end of the other of said links 'and further being connected to said slide, a substantially cylindrical roller member being received inthe recesses at the other ends of said pair of links, said pair of links and said first and second partial cylindrical bearing members and said cylindrical roller member all being of substantially the same width;

said drive means further including a movable pressure element` having convex pressure surfaces thereon, said pressure surfaces being adapted to contact and actuate each of said toggle mechanisms;

a pair of parallel bearing plates connected to said abutment member, said plates being positioned closely adjacent to and on oppositesides of said toggle mechanisms;

whereby said toggle mechanisms are mounted for free displacement between said parallel bearing plates and are capable of transmitting large clamping forces therethrough.

2. A clamping device according to claim 1, wherein said abutment member has an opening therethrough, and said drive means further includes a pushrod extending through said opening and having said pressure element tixedly connected to the end thereof, means mounting said pushrod for free movement relative to said abutment member in a direction substantially transverse to the longitudinal axis of said pushrod. v

3. A clamping device according to claim 1, wherein said parallel bearing plates are integrally connected to said abutment member so as to form a generally U-shaped member.

4. A clamping device according to claim' 3,l wherein one of said bearing plates is mounted in slideable engagement with said slide and the other bearing plate is mounted in slideable engagement with said frame means, said U-shaped member being movable relative to said frame means and said slide in the same longitudinal direction as said slide.

5. A clamping device according to claim 1, wherein a rotatable stop means is mounted on said slide for permitting adjustment of the clamping pressure, said stop means having a plurality of stop faces thereon, one of said faces being adapted to coact with said pressure member for limiting the movement thereof.

6. A clamping device according to claim S, wherein springdetent means are positioned between said slide and said stop means for releasably holding said stop means in a selected position.

7. A clamping device according to claim 6, wherein a scale is provided on the upper side of said slide in con- Centric relationship to said rotatable stop means for providing a visual indication of the selected clamping pressure.

8. A clamping deviceaccording to claim 1, wherein a nut is ltixedly connected to said frame means, and said drive means further includes a hollow spindle threadedly received in said nut and having a pushrod positioned within said spindle, said abutment member havingan opening therein, said pushrod having an end thereof extending through said opening and having said pressure element iixedly secured thereto, spring means coacting between said spindle and said pushrod for urging one end of said spindle into engagement with one side of said abutment member, said one end of said spindle being rotatably mounted on said abutment member, said spring means also urging said pushrod and the pressure element Imounted thereon against the other side of said abutment member.

9. A clamping device according to claim 8, wherein said drive means further includes rotatable crank means having a driving spindle xedly secured thereto, said driving spindle having an end thereof aligned with and rotatably supported on the pushrod, a coupling member securely connected to said hollow spindle, and releasable clutch means interconnecting said driving spindle and said coupling member.

10. A clamping device according to claim 9, wherein said driving spindle is threadedly connected to said coupling member and is supported on the pushrod by means of antifriction bearings.

11. A clamping device according to claim 1, wherein said rst and second partial cylindrical bearing members are each cylindrical roller members and said abutment member and said slide are each provided with partial cylindrical recesses therein for receiving said cylindrical roller members.

12. A clamping device for applying a clamping force to a workpiece, said device comprising:

frame means having a stationary clamp jaw fixedly secured thereto;

slide means mounted on said frame means for linear movement relative thereto, said slide means including a clamp jaw tixedly secured thereto and movable toward and away from said iixed clamp jaw;

abutment means mounted on said frame means for slideable linear movement with resp-ect to said frame means and said slide means, said abutment means being movable in a direction substantially parallel to said slide means; v

toggle means comprising a pair of toggle mechanisms connecting said slide means and said abutment means, actuation of said toggle mechanisms causing relative movement between said slide means and said abutment means;

rotatable driven means connected to said abutment means for causing linear movement thereof;

crank means for actuating said rotatable driven means whereby said abutment means and said slide means are simultaneously moved relative to said frame means;

releasable clutch means drivingly connecting said crank means and said rotatable driven means, said clutch means automatically releasing upon application thereto of a predetermined torsional resistance;

reciprocalV driven means operatively connected to said crank means and driveable thereby when said clutch means is released, said reciprocal driven means bev ing adapted to engage and actuate said toggle mechamsm;

whereby actuation of said crank means causes said abutment means and said slide means to move relative to said xed jaw until said movable jaw contacts the workpiece causing said clutch means to release, said crank means then linearly moving said reciprocal driven means to actuate said toggle mechanism f for causing the application of a large clamping pressure to the workpiece by moving the movable jaw relative to the abutment means.

13, A clamping device according to claim 12, wherein said rotatable driven means includes a hollow spindle and said reciprocal driven means includes a pushrod freely mounted within saidhollow spindle, a pressure element being mounted on one end of said pushrod and being adapted to engage said pair of toggle mechanisms.

14. The clamping device according to claim 12, wherein said rotatable driven means includes a hollow spindle having a portion thereof threadedly received in said frame means with one end of said spindle bearing against and being rotatably supported on said abutment means, and resilient means urging said hollow spindle into engagement with said abutment means.

15. The clamping device according to claimf-14, where. in said reciprocal driven means includes a pushrod positioned within said spindle, one end of said pushrodv eX- tending beyond said spindle andhaving a pressure member connected thereto for engagingA- said pair of. toggle mechanisms, the other end of said pushrod being in bear?, ing engagement withA said crankimeans, and spring means for urging said other end 4of said pushrod into bearing engagement with said crank means., y Y' .i 1

ROBERT C. RIORDON, Primary Examiner.

20 D. R. MELTON,`Assst ant Examiner'.

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