WO1991008865A1

WO1991008865A1 - Clamping mechanism for a workpiece

Info

Publication number: WO1991008865A1
Application number: PCT/AU1990/000553
Authority: WO
Inventors: John Arthur Holman
Original assignee: John Arthur Holman
Priority date: 1989-12-19
Filing date: 1990-11-19
Publication date: 1991-06-27
Also published as: AU6887991A; AU629723B2

Abstract

A clamping mechanism for a sawhorse (10) includes a fixed jaw (30) and a movable jaw arrangement (42), the movable jaw (44) of the movable jaw arrangement being able to slide along a working member (12) of the sawhorse. The movable jaw arrangement (42) includes a toggle mechanism comprising a handle (54) and a link element (58), the link element (58) being pivotally attached to a locking ring (62) which is also slideable along the working member (12). A workpiece (64) is located against the fixed jaw (30) and the movable jaw arrangement (42) is slid along the working member (12) until the movable jaw (44) contacts the workpiece (64). Depression of the handle (54) causes the link element (58) to lock the locking ring (62) to the working member (12) by exerting force between the movable jaw arrangement (42) and the locking ring (62).

Description

CLAMPING MECHANISM FOR A WORKPIECE

This invention relates to a clamping mechanism for a workpiece, and in particular relates to a clamping mechanism associated with a sawhorse.

Sawhorses are well known. Conventionally, they have been formed from wood, and include a main working member with a pair of supporting legs at each end thereof.

A workpiece - such as a board or the like - is positioned on the working member and effectively clamped by the weight of the person wishing to saw the board, usually through the use of the foot or knee. Often, two sawhorses are used, such that the board or the like rests on both sawhorses.

It is clear that in many situations a better clamp is desirable, to hold the workpiece to a sawhorse. To date, no suitable, easily-operable clamp has been suggested.

It is an object of this invention to provide a clamping mechanism for a sawhorse.

The invention provides a clamping device for a sawhorse, including fixed jaw means on or adapted to be located on said sawhorse, movable jaw means adapted to be mounted on said sawhorse for movement relative to said fixed jaw means, and a clamping mechanism for releasably locking said movable jaw means to said sawhorse, said clamping mechanism including a locking ring mounted on a working member of said sawhorse, and toggle means located between said locking ring and said movable jaw means, such that when said movable jaw means abuts a workpiece which is also in contact with said fixed jaw means, operation of said toggle means locks said clamping mechanism.

An embodiment of the invention will be described in detail hereinafter, with reference to the accompanying drawings, in which:-

Fig. 1 is a perspective view of a clamping mechanism in accordance with the invention, in place on a sawhorse;

Fig. 2 is a section through portion of the clamping mechanism and sawhorse of Fig. 1; and

Fig. 3 is a section along the lines 3-3 of Fig. 2.

The sawhorse 10 of Fig. 1 includes a main working member 12, preferably formed, from square-section steel tubing. Leg members 14,16 each include a generally U-shaped leg element 18, to the top of which is secured a connecting section 20.

Preferably, connecting section 20 has a square section slightly smaller than that of member 12, to enable it to fit within member 12. Section 20 is preferably formed form steel tubing, as is leg element 18.

Extension member 2k includes a main portion preferably substantially identical in cross-section to member 12, and a reduced-size portion 28 preferably substantially identical to connecting section 20. Bolt 22 is preferably manually operable, being locatable in a screw-threaded arrangement similar to that shown at 38 in Fig. 2, to be described hereinafter. Bolt 26 is similar in operation to bolt 22.

In Fig. 2, an internally threaded nut 38 is.shown, the nut being welded or otherwise secured to the underside of member 12, the threaded aperture of nut 38 is in register with an aperture in member 12, such that when bolt 40 is screwed up, it will advance into the interior of member 12. If section 20 is in place, bolt 40 will secure it in position in member 12.

Sawhorse 10 is advantageously painted or coated with a hard-wearing protective coating of a conventional type.

It can be seen that sawhorse 10 is demountable for transport, and to effectively extend working member 12.

Once bolt 22 (and bolt 40 of Fig. 2) has been undone, sections 20 of leg members 14,16 may be removed from member 12. To reassemble the sawhorse with extension 24, section 20 of leg member 14 is inserted into the larger-section portion of extension 24, and bolt 26 tightened. Portion 28 is inserted into member 12, and bolt 22 tightened. At the other end, section 20 of leg member 16 is inserted into member 12, and bolt 40 tightened.

The clamping mechanism includes a fixed jaw 30 and a movable jaw arrangement 42.

Fixed jaw 30 includes an L-section support, preferably formed from steel, which has a first web 32 and a second web 34. A jaw element 36 is secured ' to second web 34, and is preferably formed from material which is less likely - than steel for example - to damage a workpiece.

Fixed jaw 30 is shown permanently attached to member 12, by welding web 32 thereto, but it must be understood that fixed jaw 30 could be movable on and removable from, working member 12, and be adapted to be releasably secured in a fixed position relative to member 12.

Movable jaw arrangement 42 includes a movable jaw 44, which is similar to fixed jaw 30, except that the L-shaped support is secured to a support member 48 adapted to be movable along member 12, and is thus preferably also formed from square-section tubing, of a size slightly larger than member 12.

Located on one side of jaw 44 is a jaw element 50, similar to jaw element 3 , and on the other side are located lugs 46, pivotally attached to which at 5 is one end of a generally U-section handle 54.

Pivotally attached at 6 to handle , intermediate the ends thereof, is one end of a link element 58. The other end of link element 8 is pivotally attached , at 60 to a locking ring 62, which is adapted (Fig. 3) to receive member 12 and to move therealong. The locking ring 62, as can be seen in Fig. 3_> is of square annular shape.

The clamping mechanism operates as follows.

A workpiece 64 is placed against fixed jaw 30 and, movable jaw arrangement 42 is slid along member 12 until it is into contact with workpiece 64 to the position shown in Fig. 2. Handle 5^ is depressed from that position, such that the toggle linkage of the handle 4 and link element 58 causes locking ring 62 to tilt and jam on the working member 12 according to a known principle, and thus urges movable jaw arrangement 42 to clamp workpiece 64 between it and fixed jaw 30.

The amount of force applied to workpiece 64 is dependent upon the angle to which the operator initially lifts handle 54 after the jaw arrangement 42 has made contact with workpiece 64.

Thus the sawhorse 10 fitted with the clamping mechanism can gently or firmly clamp a range of workpieces, from small timber sections up to large sheet material, at a convenient height to be worked upon, without the need for foot or knee pressure to secure the workpiece.

The sawhorse 10 of Fig. 1 is also useful as a combined clamp and stand, for example when gluing together cabinet work.

A pair of sawhorses of the type of Fig. 1 can provide a safe trestle base for a scaffold plank, since the plank bridge can be gripped firmly against accidental dislodgement.

Claims

CLAIMS :

1. A clamping device for a sawhorse, including fixed jaw means on or adapted to be located on said sawhorse, movable jaw means adapted to be mounted on said sawhorse for movement relative to said fixed jaw means, and a clamping mechanism for releasably locking said movable jaw means to said sawhorse, said clamping mechanism including a locking ring mounted on a working member of said sawhorse, and toggle means located between said locking ring and said movable jaw means, such that when said movable jaw means abuts a workpiece which is also in contact with said fixed jaw means, operation of said toggle means locks said clamping mechanism.

2. A clamping device according to claim 1 , wherein said toggle means includes a handle for operation of said clamping mechanism, said handle being pivotally attached to said movable jaw means, and a link member, one end of which is pivotally attached to said handle, the other end of which is pivotally attached to said locking ring.

3. A sawhorse including a clamping device according to claim 1 or claim 2, said sawhorse having a working member and two detachable leg means, said fixed jaw means and said movable jaw means being located on said working member.

4. A sawhorse according to claim 3_» wherein said working member is tubular, and wherein each detachable leg means includes a portion adapted to end portion of said working member.

5. A sawhorse according to claim 4, wherein means is provided on said working member to releasably lock said portion in said working member.

6. A sawhorse according to claim 5, further including working member extension adapted to locate between one portion of one of said detachable leg means and said working member.

7. A sawhorse according to any one of claims 3 to 6, wherein said fixed jaw means is permanently attached to said working member.