GB2233027A - Clamping device - Google Patents

Abstract

A clamping device comprising two clamping units, each of which as figure 1 includes a pair of jaws and means so varying the distance between the jaws that the jaws are operable to releasably grip the article to be clamped; an elongate shaft not shown; and means 15, 16 slideably mounting the clamping units on the shaft. Mitre clamps (Fig 7) may be provided on the jaws. <IMAGE>

Description

CLAMPING DEVICE Background to the Invention The invention relates to a clamping device, for use, for example, by a do-it-yourself expert.

It is known to releasably clamp a work piece such as a piece of wood or a length of pipe, between the jaws of a vice which is, in turn, rigidly fixed to a work surface. The work piece is thus rigidly held in position, enabling the operator to work on it without having to hold it in position manually.

A development of the basic vice is embodied in the popular workbench design, such as the workbench sold under the trade mark WORKMATE by Black & Decker. This design provides a working surface formed as two separate beams with one beam being moved towards and away from the other beam by pieces which connect the beams at their end, such that each end of the beam can be movable independently so that, unlike the jaws of the vice, the movable beam does not have to remain parallel with the other beam. Because of this feature, the workbench can releasably clamp work pieces which are so shaped that they cannot be held in a simple parallel jawed vice.

However, there are some kinds of work piece, for example certain types of framework, which cannot be clamped in a workbench because they cannot be adequately accommodated between the two beams. Furthermore, the mechanisms of the workbench are elegantly designed, and one of the results of this is that the workbench is a relatively expensive piece of equipment.

Thus conventional thinking does not address the problem faced by someone needing a cheap and effective device for clamping a work piece of an awkward shape.

The invention is summarised in the numbered claims ending, and forming part of, this specification. It includes within its scope a clamping device substantially as described herein with reference to and as illustrated in any appropriate combination of the accompanying drawings.

Brief Description of the Drawings The invention will now be described, by way of example only, and with reference to the accompanying drawings in which: Figure 1 is a side view of one component of a clamping device according to the invention; Figure 2 is an end view of the component shown in Figure 1; Figure 3 is a plan view of the component; Figure 4 is a side view of part of the component; Figure 5 is a side view, partially cut away, of a modified version of the component; Figure 6 is a sectional view taken along the line A-A in Figure 5; and Figures 8 and 9 show a possible attachment for the clamping device.

Description of the Preferred Embodiment Figures 1 to 3 show a clamping unit 1 which is one of a pair of substantially identical clamping units forming part of the clamping device according to the invention. The clamping unit 1 comprises a channel sectioned rail 2, at one end of which an end plate 3 is mounted, whilst the other end is open.

A screw threaded rod 4 is rotatably mounted within the rail 2.

One end region of the rod 4 passes through a through bore in the end plate 3, and is held in position by a pair of collars 5 which are screwed onto the rod 4 and are disposed one on either side of the plate 3. A handle 6 is mounted in a gudgeon 7 formed in the end of the rod 4 adjacent the collars 5.

The clamping unit includes a fixed jaw 8 which is attached to one end of the rail 2, and which opposes, and is parallel to, a movable jaw 9. As can be seen from Figure 4, two parallel opposed plates 10 project from the base of the jaw 9, and include a pair of aligned holes 11. An interface member 12 is sandwiched between the plates 10, and is so positioned that the holes 11 are aligned with a screw threaded throughbore 13 formed in the interface member 12.

The screw-threaded bore 13 corresponds to, and engages in use, the screw-threaded rod 4. With the rod 4 so engaged, the interface member 12 is situated within the channel defined by the rail 2 (Figure 2).

Thus, by rotating the rod 4 using the handle 6, it is possible to move the jaw 9 along the shaft 4, as a result of the interaction of the bore 13 with the rod 4. Rotation of the interface member 12 about the rod 4 is inhibited by the interaction of the plates 10 with the channel defined by the rail 2.

Additionally, two lugs 14 project from opposite sides of the interface member 12, and, in use, serve to prevent the interface member 12 travelling beyond the end of the rod 4 by abutting a correspondingly positioned pair of stops (not shown) mounted at the end of the rail 2 opposite the end plate 3. The other extent of movement of the interface member 12, and hence the jaw 9, is defined by the fixed jaw 8, and occurs when the jaw 9 engages the jaw 8.

A U-section (15) is fixed to the underside of the rail 2, and together with the rail 2, defines a rectangular sectioned conduit 16. The conduit is, in use, a sliding fit on an elongate rectangular sectioned shaft (not shown).

When a work piece is to be clamped into position, two or more clamping units such as the clamping unit 1 may be so positioned on the elongate shaft (not shown) that they may be- simultaneously positioned adjacent strategic points of the work piece which may be gripped. Appropriate operation of the handle 6 of each clamping unit 1 causes the jaws 8 and 9 to grip the work piece in a similar fashion to a conventional vice. The whole arrangement, i.e. the work piece, the clamping units 1 and the elongate shaft, can then be held in position by clamping the shaft in a conventional bench mounted vice or in a workbench.

It will be seen that the clamping device is suitable for clamping, for example, work pieces which may only be held at two points. Furthermore, the device may be adapted to hold larger work pieces by simply providing a longer elongate shaft. In this way, the vice provides a degree of flexibility not available on conventional clamping devices.

Since the clamping units 1 may be completely removed from the elongate shaft, the clamping device may be easily and compactly stowed, a feature which enables the clamping units 1 to have a wider maximum jaw span than is available on a conventional vice.

The jaw span of the clamping unit 1 can be further extended using the arrangement shown in Figure 5. In this case, the jaw 9 is still mounted on the shaft 4 via a screw-threaded interface unit 12, but is spaced from the interface unit 12 by an extension 17 which is a telescopic fit within the channel defined by the rail 2. The lugs at the end of the rail 2 opposite the end plate 3 may be removable so that the jaw 9 and extension 17 may be interchangeable with the moving jaw arrangement shown in Figure 9, since the interface member 12 in each case may travel off the end of the rod 4 and the rail 2.

Movement of the jaw 9 towards the jaw 8 in Figure 5 will be limited by the end of the extension 17 opposite the jaw 9 engaging the end plate 3. Unlike the arrangement in Figure 1, the jaws 8 and 9 cannot be brought into contact, but the extension 17 practically doubles the maximum span of the jaws 8 and 9.

Referring to Figure 7, the clamping unit 1 may be used in conjunction with a mitre clamp 18. The mitre clamp 18 includes a clip 19 which, in use, fits over one of the jaws 8 or 9.

Figure 8 shows a similar sort of mitre clamp 20, from the underside, which fits over a jaw 8 or 9 in a similar way.

Although the clamping device just described uses a single elongate shaft, it is within the scope of the invention to have the clamping units slideably mounted on an array of shafts arranged in, for example, an 'H' framework.

When the jaws 8 and 9 grip part of a workpiece situated between them, that part of the workpiece is engaged by the inner surface of each jaw, the surface facing the opposed jaw.

Alternatively, the jaws 8 and 9 can grip an appropriately shaped workpiece which is not situated between the jaws, by engaging the workpiece with the outer surface of each jaw, the surface facing away from the opposed jaw.

In this case, both the jaws 8 and 9 are initially positioned within the parts of the workpieceto be gripped, for example the legs of an 'H' shaped frame. The handle 6 is then operated to increase the distance between the jaws 8 and 9, and thus to expand the clamping unit 1 until the respective outer surfaces of the jaws 8 and 9 engage the workpiece. As the handle 6 is used to tighten the moving jaw 9 against the workpiece, the reaction to the force exerted on the workpiece by the moving jaw 9 increases the force of contact between the jaw 8 and the other part of the workpiece (provided the workpiece remains substantially rigid).

Claims (3)

CLAIMS:

1. A clamping device comprising two clamping units, each of which includes a pair of jaws and means so varying the distance between the jaws that the jaws are operable to releasably grip the article to be clamped; an elongate shaft; and means slideably mounting the clamping units on the shaft.

2. Fpr use on a system according to claim 1, a clamping unit in which the means varying the distance between the jaws comprise a screw-threaded rod, on which at least one of the jaws is mounted via a correspondingly threaded connector; and means rotating the rod about its elongate axis.

3. A clamping unit according to claim 1 in which the screw-threaded rod is mounted within an elongate channel sectioned rail, and in which one of the jaws is mounted on the screw-threaded rod via an extension which telescopes within the rail, the arrangement being such that the extension serves to increase the span of the jaws.