Work holders – Relatively movable jaws – Three coacting work grippers
Patent
1992-09-16
1994-09-27
Watson, Robert C.
Work holders
Relatively movable jaws
Three coacting work grippers
269217, 269233, 269258, 269266, 269268, 269902, B25B 100
Patent
active
053501632
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a clamping member and in particular to a clamping member for holding rigid work pieces. The invention has been developed primarily for use in a wood clamp and the invention is hereinafter described in such context. However, it would be appreciated that the invention is not limited to this particular field of use and may be used for supporting or clamping any of a range of rigid work pieces.
BACKGROUND ART
In the past, various clamping arrangements have been proposed for clamping or supporting work pieces. A commonly used clamping arrangement is the vice which consists of two plates which are drawn together by a lead screw. While the vice is effective for holding a single work piece, or for holding parallel work pieces, it is not versatile in that the device cannot adequately cater for irregular shaped work pieces.
U.S. Pat. No. 4,767,110 (Yang) discloses a modified vice arrangement to cater for irregular shaped work pieces. Yang discloses a work table incorporating first and second vice jaws, each of which incorporate a series of connection holes. At least three clamping claws are removably mounted to the connection holes of the vice jaws, and are arranged such that one of the claws is located in one of the jaws where the other two claws are located in the other jaw. The claws are mounted to the connection holes via shanks and these shanks are eccentrically located on the claws. In this way, the respective claws can be independently moved out of respective connection holes and inserted in a different connection hole to provide longitudinal adjustability of the claws independent of the vice jaws. The claws are further arranged to rotate about their respective shanks to provide individual angular adjustability.
With the arrangement as disclosed in Yang, a work piece is clamped by firstly locating the claws in appropriate connection holes such that they are as close to the work piece as possible. The vice jaws are then brought together and at least some of the claws are rotated until such time that all the individual claws apply a force and clamp the work piece. To assist in rotation of the claws, each claw is provided with a push handle.
While the Yang patent does enable greater flexibility of the type of work pieces which can be clamped, it does have the limitation that it is required to be located on a work bench and furthermore rapid adjustment of the claws is not possible. Furthermore, the actual clamping of the work piece is difficult in that it is necessary to bring the vice jaws together, while simultaneously applying pressure on each push handle to apply a force normal to the contact surface to ensure that the claws grip the work piece properly. This applied normal force is required if there is not sufficient frictional force between the work piece and the claws to prevent the work piece from merely sliding between the two clamping claws, rather than gripping the work piece and rotating to effect clamping.
DISCLOSURE OF INVENTION
The present invention aims at providing a clamping member which ameliorates at least some of the above problems.
Accordingly, in a first aspect the present invention provides a clamping member comprising a support plate and a pair of engaging elements, the support plate incorporating a pair of converging slots, and each engaging element incorporating a wall surface of which at least a portion is arcuate in shape and is formed from a non-slip material, a respective one of the engaging elements being captured in a respective one of the slots and each engaging element being arranged to extend outwardly from a first side of the support plate such that the wall surfaces of the engaging elements are opposed to each other, each engaging element being slidable in its respective slot and each engaging element being mounted to the support plate via low friction bearings such that each engaging element can freely rotate relative to the support plate about an axis of rotation, thereby enabling the distance between the opposing wall
REFERENCES:
patent: 413780 (1889-10-01), Griswold
patent: 1349963 (1920-08-01), Jerrim
patent: 2541605 (1951-02-01), Ohlsson
patent: 2698550 (1955-01-01), Hill
patent: 2754528 (1956-07-01), Pinkerton
patent: 2806380 (1957-09-01), Martin
patent: 2850931 (1958-09-01), Conway
patent: 3190216 (1965-06-01), Keller
patent: 3199840 (1965-08-01), Lindsey
patent: 4157819 (1979-06-01), Meyer
patent: 4579322 (1986-04-01), Schwarz
patent: 4767110 (1988-08-01), Yang
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