GB2320454A - Portable clamp - Google Patents

Abstract

A portable clamp particularly suitable for holding a door during the fitting thereof comprises a foot portion 10 adapted to rest on the ground and an abutment 11, 12 for engaging one face of a workpiece. A clamping member 13 is slidably mounted on the foot portion 10 for movement towards and away from the abutment 11, 12. A drive arrangement for the clamping member 13 includes a first pedal 17 to effect incremental advancement of the clamping member on each depression of the first pedal and a releasable lock 25 to hold the clamping member at a position to which it has been driven by the first pedal 17. The lock 25 may be released by depression of a second pedal 28.

Description

A PORTABLE CLAMP This invention relates to a portable clamp, and in particular - but not exclusively - to a portable clamp to assist working on relatively large work-pieces, such as a door.

There is a large number of different types of clamp, all intended to hold a work-piece in order to facilitate some kind of operation on that work-piece. There is however a need in the carpentry and building trades for a relatively small and easily portable clamp which is able to hold a large work-piece such as a door, in order to allow operations to be performed on that door during the act of fitting it to a frame. In the building industry, it is the usual practice for a door to be oversize for an intended doorway and then to cut the door to the required size in order closely to fit within a frame already provided within the doorway. This necessitates using either a saw or a plane, depending upon the amount to be removed, to reduce the size of the door. During either operation, the door must suitably be held in a convenient position for a carpenter to perform the required operations. In addition, once the door has been cut to size, the latch, lock mechanism and knob assembly must be fitted to the door and again the door has to be held in a suitable manner to permit the drilling of the required holes, and so on.

Not infrequently, carpenters employ portable workbenches in order to hold work-pieces such as doors. A work-bench is at the wrong height if a door is to be held on edge, but as there is nothing else conveniently available for this purpose a carpenter usually has to struggle as best he can, when a work-piece such as a door is to have operations performed on it.

The present invention aims at addressing the above problem, by providing a portable clamp which may be used with work-pieces such as doors, in order to hold those work-pieces in a secure manner and in such a way as to allow the work-pieces to stand on edge and give access to those edges for whatever operation needs to be performed.

According to the present invention, there is provided a portable clamp comprising a foot portion adapted to rest on the ground, an abutment upstanding from the foot portion for engaging one face of a workpiece, a clamping member slidably mounted on the foot portion for movement towards and away from the abutment whereby a work-piece may be held there between, drive means arranged to advance the clamping member incrementally towards the abutment, a first pedal connected to the drive means to effect incremental advancement of the clamping member on each depression of the first pedal, releasable locking means to hold the clamping member at a position to which the member has been driven by the drive means, and a second pedal connected to the locking means to effect release thereof on depression of the second pedal.

The clamp of the present invention is adapted to rest on the ground and to hold a work-piece such as a door between and abutment and an adjustable clamping member. The pedal arrangement allows an operator to use his foot for tightening the clamping member and so the operator has both hands free for holding the door, until stability is imparted to the door by virtue of the clamp gripping the door. When the door is to be released the operator may again use both hands to hold the door to prevent it falling, and then use his foot to release the clamp by depressing the second pedal.

Once a door has been hung, it is frequently necessary to perform various operations on the door, such as drilling, chiselling, planing, fitting of locks and so on. The clamp of this invention may be employed on a door once it has been hung and whilst it remains connected by its hinges to a frame, so as to impart stability to the door and facilitate such operations as may be required. In addition, the clamp may be secured to the floor or a wall surface in order to assist the holding of large work-pieces.

The drive means for the clamping member may comprise a ratchet mechanism arranged to advance the clamping member in a step-wise manner, on each depression of the first pedal. In this way, the clamp may be opened relatively widely in order to permit a door to be located between the abutment and the clamping member, and then the clamp may be tightened on to that door by repeated depression of the first pedal. In a similar way, the locking means may comprise a releasable one-way ratchet device which responds to the step-wise advancement of the clamping member to hold the door.

In a preferred form of clamp of this invention, the clamping member is mounted on a drive rod which is slidably supported in a journal provided on the foot portion, for movement substantially parallel to the ground on which the foot portion rests. In this case, the drive means may include a plate having an aperture through which the rod extends, and spring means to urge the plate away from the clamping member against a shoulder extending substantially perpendicularly to the length of the rod. The plate may be operated by the first pedal, which is pivoted to a fixed component attached to the foot portion and is arranged to drive the plate against the action of the spring mean. The plate will become inclined and jam against the rod whereafter continued depression of the first pedal will drive the rod to advance the clamping member nearer to the abutment.

The locking means may operate in a generally similar manner, with a further plate having an aperture through which the rod extends and further spring means acting between a fixed part and the further plate to urge the further plate away from the clamping member. A fulcrum should be provided for the plate and about which the plate pivots under the action of the spring means, to cause the plate to become inclined to the length of the rod thereby to engage and lock the rod against movement away from the abutment unless released by the second pedal. The second pedal may also be pivoted to a fixed component attached to the foot portion, in a generally similar manner to that of the first pedal.

The foot portion should be of such a size that it permits the stable holding of a work-piece. In the case of a door, it is found that the foot portion imparts sufficient stability for most operations if it is in the form of an elongate plate which, in use, extends perpendicularly to the area of the door, to both sides thereof. Such a plate may typically be about 300-500 mm long and about 25-50 mm wide. The foot portion conventionally is of a shallow height so as not unduly to lift the work-piece above the floor, and typically may be only 5 mm or so thick.

By way of example only, one specific embodiment of clamp device of this invention will now be described in detail, reference being made to the accompanying drawings, in which: Figure 1 is a general perspective view of the embodiment of clamp device, in use to hold a door; Figure 2 is a side view of the clamp device of Figure 1; and Figure 3 is a plan view of the clamp device.

The embodiment of clamp device of this invention has a base plate 10 which supports an abutment 11 upstanding from the base plate adjacent one end thereof. The abutment 11 is reinforced by a pair of triangular plates 12, secured for example by welding to both the abutment and the base plate. A circular clamping member 13 is mounted on a rod 14 journalled in a pair of blocks 15 and 16 for sliding movement towards and away from the abutment 11, parallel to the length of the base plate 10.

Both the abutment 11 and the clamping member 13 may be provided with soft facings (not shown), to avoid damaging a work-piece clamped therebetween, such as door 16 illustrated in Figure 1.

The rod 14, and so the clamping member 13 may be moved in a series of steps towards the abutment 11 by means of a drive mechanism including a first foot pedal 17. A washer 18 is located on the rod 14 and is urged away from abutment 11 by a spring 19 acting on block 15 and on the washer. The first pedal 17 is pivoted by pin 20 passing through a pair of side plates 21 and 22 and has an extension 23 which engages washer 18. Initial depression of the first pedal 17 thus pushes the upper part of the washer 18 (in Figure 2) so canting the washer against the action of spring 19 and jamming that washer on to the rod 14. Further depression of the pedal drives the washer 18 together with the rod 14 to the left, so advancing the clamping member 13 nearer the abutment 11.

A locking mechanism is provided for the rod 14, to prevent the rod 14 moving to the right in Figure 2. This locking mechanism includes a further washer 25 also surrounding the rod 14 and engaged with a pin 26 extending between the side plate 21 and 22, adjacent an upper part of the further washer. A spring 27 acts between the block 16 and further washer 25, to urge that washer away from the abutment 11. In view of the engagement of that washer with pin 26, the washer becomes inclined to the axis of the rod 14, as illustrated in Figure 2, and jams on the rod 14. An attempt to move the rod 14 to the right will increase the jamming effect of the washer and in view of the engagement of the washer with pin 26, the rod will be prevented from moving in that direction. Should, however, the first pedal 17 be depressed, moving the rod to the left (in Figure 2), the inclination of the further washer 25 will be reduced and so the washer will be released from the rod 14 to permit the movement of the rod to take place.

A second foot pedal 28 is pivoted by pin 29 to the side plates 21 and 22 and is arranged to act on a lower portion of the further washer 25, to move the washer against the action of spring 27. When the further washer is moved in this way, it is released from the rod 14 and so permits that rod to slide freely in either direction.

A knob 13 is furnished on the free end of rod 14, beyond the base plate 10. This knob may be used for moving the rod 14 manually to pre-set the clamping member 13 at some desired position. Also, when the clamp has been opened fully and a work-piece (such as door 16) has been positioned between the abutment 11 and the clamping member 13, the knob 30 may be kicked to bring the clamping member 13 lightly into engagement with the door.

Then, one or more strokes may be applied to the first foot pedal 17 so as to tighten the clamp to the required extent and firmly grip the door.

When an operation on the door has been completed, the clamp may be released by depressing the second foot pedal 28, so allowing the clamping member 13 to move away from the abutment 11. The door may then be lifted from the clamp.

The base plate 10 may be provided with holes (not shown) to permit the clamp to be secured by screws to a floor or to a wall surface such as a door frame. In this way, the clamp may be used to hold in a more secure manner a work-piece such as a door and to facilitate various operations on that work-piece.

Claims (12)

1. A portable clamp comprising a foot portion adapted to rest on the ground, an abutment upstanding from the foot portion for engaging one face of a work-piece, a clamping member slidably mounted on the foot portion for movement towards and away from the abutment whereby a work-piece may be held therebetween, drive means arranged to advance the clamping member incrementally towards the abutment, a first pedal connected to the drive means to effect incremental advancement of the clamping member on each depression of the first pedal, releasable locking means to hold the clamping member at a position to which the member has been driven by the drive means, and a second pedal connected to the locking means to effect release thereof on depression of the second pedal.

2. A portable clamp as claimed in claim 1, wherein the drive means comprises a ratchet mechanism arranged to advance the clamping member.

3. A portable clamp as claimed in claim 1 or claim 2, wherein the locking means comprises a releasable one-way ratchet device.

4. A portable clamp as claimed in any of claims 1 to 3, wherein the clamping member is mounted on a drive rod which is slidably supported in a journal provided on the foot portion, for movement substantially parallel to the ground on which the foot portion rests.

5. A portable clamp as claimed in claim 4, wherein the drive means includes a plate having an aperture through which the rod extends, and spring means to urge the plate away from the clamping member against a shoulder extending substantially perpendicularly to the length of the rod.

6. A portable clamp as claimed in claim 5, wherein the first pedal is pivoted to a fixed component attached to the foot portion and is arranged to drive the plate against the action of the spring means, thereby to incline and engage the plate with the rod and then to advance the clamping member on continued depression of the first pedal.

7. A portable clamp as claimed in any of claims 2 to 6, wherein the locking means includes a further plate having an aperture through which the rod extends, and further spring means acting between a fixed part and the further plate to urge the further plate away from the clamping member, a fulcrum being provided for the plate and about which the plate pivots under the action of the spring means to be inclined to the length of the rod thereby to engage and lock the rod against movement away from the abutment.

8. A portable clamp as claimed in claim 7, wherein the second pedal is pivoted to a fixed component attached to the foot portion and is arranged to drive the further plate against the action of the further spring means, thereby to free the further plate from the rod and allow the clamping member to move away from the abutment.

9. A portable clamp as claimed in claim 5, wherein there is a further journal for the rod spaced from the first journal, on the side thereof remote from the clamping member, and the spring means acts on the first journal to urge the plate into engagement with one axial face of the further journal.

10. A portable clamp as claimed in claim 9, wherein the further spring means acts on the other axial face of the further journal.

11. A portable clamp as claimed in any of the preceding claims, wherein the foot portion is in the form of an elongate substantially flat strip.

12. A portable clamp as claimed in claim 1 and substantially as hereinbefore described, with reference to and as illustrated in the accompanying drawings.