Fast Action Clamps

Abstract

Applicant's invention comprises a novel linkage configuration for toggle actuated clamping devices. The linkage is particularly suitable for portable hand clamps; also, for fixed base and power operated clamps. The linkage provides about one-half the normal handle or actuator movement for a full opening of the clamp jaws in comparison with the prior art toggle linkages.

Description

BACKGROUND OF THE INVENTION

Toggle actuated clamps have been well known in the art for providing relatively large clamping forces with a minimum of effort. Additional improvements have provided for a relatively large angular sweep of the jaws in addition to the large clamping forces upon closing. Generally however, the angular sweep of the handles in the case of a portable hand operated clamp has been much larger than the angular sweep of the jaws, despite the fact that the high leveraging to provide high clamping forces in the closed position is provided by the toggle mechanism without the requirement of high closing forces over the greater portion of the angular sweep of the jaws. The large angular sweep of the handles in the case of the hand operated clamps and the relatively large stroke required for power operated clamps results in awkwardness in the case of the hand operated clamp and a large stroke and therefore relatively large actuator for fixed base and power operated clamps.

SUMMARY OF THE INVENTION

Applicant's new linkage as applied to a hand operated clamp includes an additional pivot and two additional cross links so positioned that the angular sweep of the handles is substantially one-half of the angular sweep required by prior art toggle linkage without any detriment to the final clamping pressure generated by the toggle action. The new linkage utilizes the two additional links to join the clamp arms across the toggle mechanism as opposed to the single pivotal connection between the clamp arms in the prior art. The result is an angular sweep of the handles in the order of 50.degree.-60.degree. for a clamping jaw total sweep of 90.degree. as opposed to a prior art handle sweep of over 100.degree. for a total 90.degree. jaw sweep.

DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a front elevation of a symmetrical clamp according to the invention in open position;

FIG. 2 shows the clamp of FIG. 1 in closed position;

FIG. 3 is a sectional view taken along the line 3--3 of FIG. 2;

FIG. 4 is a side elevation of the clamp in closed position;

FIG. 5 is a fragmentary view of the clamp mechanism taken in the direction 5--5 of FIG. 2;

FIG. 6 illustrates a prior art asymmetrical clamp in closed position;

FIG. 7 illustrates a corresponding asymmetrical clamp according to the present invention in closed position;

FIG. 8 illustrates the clamp of FIG. 7 in open position;

FIG. 9 is a fragmentary view of the clamp taken in the direction 9 of FIG. 7;

FIG. 10 illustrates a fixed base clamp according to the invention in open position;

FIG. 11 illustrates the clamp of FIG. 10 in closed position; and,

FIG. 12 illustrates a power operated clamp according to the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

In FIGS. 1 thru 5 a portable hand operated clamp is shown having clamping arms 20 and 22 carrying adjustable work piece contacting heads 24 and 26. The clamp is actuated by two handles 28 and 30 and includes a lever bar 32 pivotally pinned at 34 to assist in unlocking the toggle action of the clamp when it is closed. The two handles 28 and 30 are pivotally joined at 36 along with links 38 which support the pivot 34. The handle link 28 is pivotally connected to the clamping arm 29 at the pivot 40. Similarly, the handle link 30 is pivotally connected to the clamping arm 22 by the pivot 42. Attached to the pivot 42 is a cross link 44, the other end of which is pivotally connected to the clamping arm 20 by the pivot 46. Similarly, attached to the pivot 40 is a cross link 48, the other end of which is pivotally connected to the clamping arm 22 by the pivot 50. The various pivots may comprise rivets as shown or other suitable pivotal connections.

Mounted on the link 44 is a stop 52. A similar stop 54 is mounted on the other link 48. The stops 52 and 54 prevent the nose portion of the toggle 56 which comprises portions of the handle links 28 and 30 adjacent the pivot 36 from moving beyond the toggle closed position when the clamp is closed as shown in FIGS. 2 and 3. A fully opened stop 58 is attached to clamping arm 20 and similarly a fully open stop 60 is attached to clamping arm 22. The stop 58 fully engages the link 44 and the stop 60 fully engages the link 48 when the clamp is fully open as best shown in FIG. 1. The stops 58 and 60 are provided to prevent excessive opening and potential jamming of the clamp. More particularly, in order to facilitate closing by handle actuation without excessive resistance, a line 62 joining the center of pivots 46 and 40 preferably should not make an angle of less than 15.degree. with a line 64 joining the centers of pivots 40 and 42 and 20.degree. is desirable for free action. When the handle links 28 and 30 are operated to close the clamp, the additional links 44 and 48 create a push-pull action which compounds the opening motion of the clamping arms 20 and 22.

The new linkage is also applicable to asymmetrical portable hand operated clamps, as shown in FIGS., 7 thru 9, which may be compared with the asymmetrical prior art clamp of FIG. 6, having a single central pivot 272 connecting the clamping arms 220 and 222. The prior art clamp of FIG. 6 does not provide the push-pull action of the additional links and pivots in applicant's clamps. In FIGS. 7 thru 9, parts corresponding in function to the parts in FIGS. 1 thru 5 are numbered the same with the addition of a preceding 1 and operate in exactly the same manner. The handle links 228 and 230 in FIG. 6 must sweep a combined arc greater than the combined arc swept out by the clamping arms 220 and 222, whereas in the applicant's clamps, as shown in the drawings, the arc swept out by the handle links 128 and 130 is much less than the combined arc of the clamping arms 120 and 122. For example, in the illustrated embodiment a 90.degree. jaw opening is achieved with a 56.degree. handle opening. Aside from the asymmetrical configuration of the clamping arms 120 and 122, other modifications are included as optional choices. The opening assist lever arm 132 is pivotally attached at 134 directly to the handle link 130. However, it operates basically the same as the lever arm 32. A spring assist is provided for quickly opening the clamp. The spring assist comprises a spring 166 attached to the arm 122 at the pivot 150 and coiled thereabout as shown. The other end of the spring extends around the end 168 of the link 144 and is attached thereto by the pin 170. The spring fully opens the clamp when the toggle locking action is released.

In FIGS. 10 and 11, applicant's invention has been applied to a fixed base clamp wherein the clamping arm 322 carries an adjustable clamping head 326 for clamping a work piece down to a bed plate or the like not shown. The base of the clamp 320 is fastened to the bed plate or other supporting surface by means of bolts or other fasteners extending through holes 321. The base 320 supports two pivots 346 and 340 corresponding to pivot 46 and 40 of the hand clamp above. Pivoted at 340 is the handle link 328 carrying the handle 329. The handle link 328 in turn is pivoted at 336 to a second link 330 which at the other end is pivoted at 342 to the clamp arm 322. Pivotally attached at 346 to the base 320 is the link 344 which is also pivotally attached at 342 to the clamping arm 322. On the opposite side of the clamping arm 322 the other link 348 is pivotally attached at 350 and extends to the pivot 340 where it is attached to the base 320.

The linkage is thus equivalent to the hand clamp linkage and provides the same angular sweep to the clamping arm 322 relative to the base 320 as the clamp arm 22 provides relative to the clamp arm 20 in FIG. 1. In addition, the link 330 corresponds to the handle link 30 of the hand clamp. The link 328 with the handle 329 attached provides for natural hand movement when opening or closing the clamp since the clamp and handle motion are both in the same angular direction. However, the handle 329 could alternatively be attached to link 330 with the result that the handle and clamp arm would move in opposite rotative directions.

As shown the handle link 328 and handle 329 are configured to provide a contact stop in closed position at 374, thus providing a limit for the toggle locking action. The handle 329 and link 328 are configured to abut either or both the link 344 and the clamping arm 322 adjacent the pivot 342. In FIG. 10 a stop 358 is provided as an opening limit for the fixed base clamp.

In FIG. 12, the fixed base clamps of FIGS. 10 and 11 is further modified to show operation with a fluid powered cylinder. As shown, the base 440 is extended to provide support 476 which is fastened to the bed plate or other supporting surface by means of bolts or other fasteners extending through holes 421. The support 476 includes a trunnion pivot 478 to which a fluid powered double acting cylinder 480 is attached. The piston rod 482 of the cylinder 480 is threadably attached at 484 with a lock nut 486 to a clevis 488. The clevis 488 in turn is pivotally attached at 490 to a modified link 428 of the clamp linkage which corresponds to the handle link 328 in FIG. 10. For the remaining elements of the clamp the 400 series numbers correspond to the 300 series numbers above.

Other power operated means may be substituted for that shown or adapted to actuate link 430 rather than link 428.

Claims

I claim:

1. A clamp having two spaced means for opposed angular relative clamping movement therebetween and each having a first pivot, actuation link members each attached at a different one of the first pivots and pivotally attached together to provide a toggle action between said first pivots, and characterized by a second pivot adjacent the first pivot on each of the opposed spaced means, two cross links attached each at one end to each second pivot, and each cross link having its other end pivotally attached to the other opposed spaced means, the attachment of the cross links being such that an imaginary line joining the centers of the pivots of one cross link intersects an imaginary line joining the centers of the pivots of the other cross link.

2. The clamp of claim 1 wherein each cross link has its other end pivotally attached to the first pivot of the opposed spaced means.

3. The clamp of claim 2 wherein the opposed spaced means comprise a clamping arm and a base, and the actuation link members include at least one handle for hand actuation.

4. The clamp of claim 3 wherein the angular movement of the handle is less than the angular movement of the clamping arm relative to the base.

5. The clamp of claim 3 wherein at least one actuation link member is engageable with at least one of the cross links and clamping arm to provide a limit for the toggle action in closed position.

6. The clamp of claim 3 wherein the base includes a stop for engagement with one of said cross links to provide a positive limit to the open position.

7. The clamp of claim 2 wherein the opposed spaced means comprise a clamping arm and a base, and the actuation link members include at least one link adapted for actuation by a powered actuator.

8. The clamp of claim 7 wherein the angular movement of the powered actuation link is less than the angular movement of the clamping arm relative to the base.

9. The clamp of claim 7 including a powered actuator comprising a trunnion mounted fluid cylinder having a clevis on the piston rod pivotally attached to the powered actuation link.

10. The clamp of claim 7 wherein the powered actuation link is engageable with at least one of the cross links and clamping arm to provide a limit for the toggle action in closed position.

11. The clamp of claim 7 wherein the base includes a stop for engagement with one of said cross links to provide a positive limit to the open position.

12. The clamp of claim 2 wherein the opposed spaced means comprise clamping arms to clamp a workpiece therebetween and the actuation link members include handles for hand actuation.

13. The clamp of claim 12 wherein the angular movement of the handles is less than the angular movement of the clamping arms.

14. The clamp of claim 12 including spring means attached to one of said cross links and the adjacent clamping arm, and adapted to provide a spring assisted opening motion to the clamp.

15. The clamp of claim 12 wherein said clamping arms are symmetrically positioned about a plane evenly spaced between the first pivots and second pivots respectively and parallel thereto.

16. The clamp of claim 12 wherein said clamping arms are asymmetrically positioned about a plane evenly spaced between the first pivots and second pivots respectively and parallel thereto.

17. The clamp of claim 12 wherein at least one of said cross links includes a stop engageable by at least one of the actuation link members to provide a limit for the toggle action in closed position.

18. The clamp of claim 12 wherein at least one of said clamping arms includes a stop for engagement with one of said cross links to provide a positive limit to the open position.

19. A toggle clamp comprising a pair of clamp jaw elements, a pair of handle elements, a pair of link elements, a first pivotal connection common only to said handle elements, second and third pivotal connections each common respectively to a different one each of said jaw, handle and link elements and fourth and fifth pivotal connections each between a different one each of said jaw and link elements, the two pivotal connections of each link element providing a different link interconnection between said jaw elements.

20. The clamp of claim 19 wherein the interspacing of said five pivots provides a jaw opening of 90.degree. with a corresponding handle opening in the order of 2/3 of the jaw opening and wherein linkage connections provide reversible actuation for handle closing of said clamp from said 90.degree. opening.