GB2186822A - Clamp - Google Patents

Abstract

An adjustable clamp 1 has a clamping arm 3 comprised of a laminated clamping part 7 with jaw 16 and an adjustment part 9. The part 7 is lockable to part 9 by a splined gear member 10 axially movable between locking and unlocking positions. After coarse adjustment of clamping part 7 and locking adjustment means 6 provides a fine adjustment to finally clamp a workpiece. The adjusting means 6 may be interchangeable for selective manual or fluid operation. <IMAGE>

Description

SPECIFICATION Improvements in or relating to clamps This invention relates to improvements in or relating to clamps and is more particularly but not exclusively concerned with adjustable clamps having a body part mountable to a work table and a pivotable clamping arm (hereinafter referred to as 'of the type specified').

Clamps of the type specified are well known but some of these clamps may tend to be disadvantageous in one or more respects or at least do not present an optimised design which is as efficient and user friendly as it might be. For example, it may be advantageous to ensure that a workpiece can be quickly accommodated on the worktable, quickly and reliable clamped in position whilst a work operation is performed on the workpiece, and quickly released so that it may be moved relative to the clamp to allow a new workpiece to again be quickly clamped in position where the whole cycle is repeated. A quick, reliable, safe and easily operated clamping and unclamping action can be advantageous to the operator, speed up production and aid a more cost-effective production method.

In order to achieve a quicker clamping action it is known for the clamping arm to be basically of two part construction so that the first, clamping part is releasable from the second part and pivotable relative thereto in order to quickly but coarsely position this clamping part of the arm relative to a workpiece. Once the clamping part has been positioned as close to the workpiece as may be allowed by said coarse adjustment the final clamping position is achieved by adjustment means operating on said second part, when the second part is locked to the clamping part. This arrangement tends to have several disadvantages. Firstly, and it is believed most significantly, the coarse adjustment has limitations in that only a few positions (perhaps three) of the clamping part relative to the second part may be selected.Such a coarse adjustment is provided to reduce the amount to time taken to finally clamp the workpiece using the adjustment means operating on the second part; a significant amount of time may be taken to move the clamping arm through a large angle using the adjustment means alone. Nevertheless, the coarse adjustmerit provided for seems relatively crude and it may still be necessary, even after the coarse adjustment, to operate the adjustment means to cause the clamping arm to move through a relatively large pivoting angle (perhaps 30 ), with a corresponding increase in time and effort necessarily having to be expended to finally clamp the workpiece.The principle of the coarse adjustment is based on aligning a hole in the clamping part with one of several holes in the second part and introducing a pin through the aligned holes to yield only several coarse adjustment positions. Because of necessary strength characteristics required for the clamping and so forth (affecting minimum pin diameter and space needed between holes on the second part) it is by no means envisaged how such a principle may be extended in practice to provided a whole range of coarse adjustment positions (perhaps ten or more).

Additionally, this arrangement does not provide for a self-alignment of the clamping part and second part before operation of the locking means and it is, therefore, necessary to hold the clamping part exactly in the correct position with its hole aligned with one of the holes on the second part whilst locking of the clamping part and second part is effected.

This trial and error method of effecting the necessary alignment whilst locking may cause inconvenience and perhaps even lead to undue wear of the parts concerned. Also, the body part of the clamp has to be cut away on one side to reveal the holes and locking means thereby seemingly weakening the overall structure as well as restricting the angle of rotation of the clamping arm (in particular of the clamping part relative to said second part).

This means that the clamping part cannot be raised to an angle which is at or near to the vertical which would be a desirable feature to allow totally unobstructed removal of the workpiece, which in some cases might not otherwise be possible. There may be other disadvantages of the arrangement since it is open to the ingress of dust and perhaps swarf and the like from the workpiece which could affect the locking mechanism and perhaps invite the operator to damage a finger in attempting to clean the area (or even whilst applying the locking mechanism) with undue care and attention. It is not thought necessary to indicate any further disadvantages of this course adjustment mechanism.

Other clamps of the type specified have an adjustment means operating on the clamping arm (which arm may be in one piece or of the previously described two part construction) and this may comprise a purely mechanical worm arrangement with a head piece shaped (for example as an elongated hexagon head) for tightening up by a spanner tool or the like.

Alternatively, the adjustment means may instead be hydraulic. The provision of hydraulic adjustment means has obvious advantages although it may increase the overall cost of the clamp to a very large extent and it tends to be disadvantageous that a choice has to be made between the two types of clamp with different adjusting means.

Clamps of the type specified tend to be subject to other disadvantages, for example the clamping arm carries a loosely pivotable jaw at the free end thereof, and the stacking of the body part onto one or more packing blocks to accommodate progressively taller workpieces appears to be provided for in a manner which is capable of improvement. It is also believed that the inherent design of the hydraulic equipment (for clamps with hydraulic adjusting means) tends not to be as efficient as it could be.

Accordingly, it is an object of the present invention to at least alleviate one or more of the aforementioned disadvantages.

According to one aspect of the present invention there is provided an adjustable clamp comprising a body part which is, in use, mountable to a worktable, a clamping arm being pivotally mounted on said body part, the pivotal movement of the arm relative to the body part (and relative in use to a workpiece on the worktable) being adjustable by adjusting means on said clamping arm to clamp a workpiece, and in which said clamping arm is of at least two part construction whereby the first of said at least two parts comprises a clamping part and the second of said at least two parts comprises an adjustment part, said first, clamping part being selectively releasable from and selectively lockable to said second, adjustment part thereby allowing said clamping part to be pivoted relative to the second part, in order to quickly position the clamping part relative to a workpiece before the clamping part is selectively locked to the adjustment part and the adjusting means operated to clamp the clamping part to the workpiece by way of said adjustment part, said clamp having one or more of the following features, a) locking means mounted on the pivotal axis of the arm which is axially movable in one direction along the pivotal axis to lock the clamping part and adjustment part together, and axially movable in the reverse direction to release said clamping and adjustment parts from one another, b) locking means comprising a gear or spline which is movable into and out of intermeshing engagement with the arm to lock and release the clamping part to and from the adjustment part, c) the arrangement being such that the clamping part is pivotable to within a coarse adjustment of about 9" to 11" of any required clamping position throughout the whole range of clamping positions before being locked to the adjustment part when a finer adjustment of the clamping position can be effected by said adjusting means, d) locking means to lock the clamping part to the adjustment part and self-alignment means which automatically aligns the clamping part, adjustment part and locking means prior to operation of the locking means to lock said clamping part to the adjustment part, e) locking means to lock the clamping part to the adjustment part such that when released it allows the clamping part to be swung upwards to give clearance for the workpiece to be removed in a generally vertical direction.

Preferably, the clamping part is of laminated form and may comprise three plates fixed together, for example, by rivetting. The adjustment part may comprise two plates arranged one on each side of the clamping part.

In one embodiment of the present invention, locking means, or the locking means, comprises an axially movable toothed gear or spline which pivots with the clamping part relative to the adjustment part for coarse adjustment, the gear, clamping part and adjustment part meshing together during clamping.

Where the clamping part is laminated as aforesaid the central plate may be toothless and have a slightly larger diameter receiving hole for the gear that the other plates of the clamping part. The gear (locking means) may be provided with one or more spring loaded detents (preferably in the form of balls) located in radial bores in the gear. The spring loaded detent/s act to align the clamping part, adjustment part and gear, along the gear axis, whilst the clamping part is locked to the adjustment part, by being located on the central plate in between gear teeth on the other two plates of the clamping part (and thus in a circumferential groove formed in between these two plates). This provides an axial selfalignment or syncromesh of the gear (locking means) relative to the clamping arm.

Further, the detent or detents may provide an automatic radial or angular self-alignment or syncromesh of the gear (locking gear) relative to the clamping arm in the released position i.e. during coarse adjustment of the clamping part before operation (axial movement) of the gear (locking means) to lock the clamping part to the adjustment part. In the released position the detent/s may ride on internal teeth on one of the plates of the adjustment part yielding an audible 'clicking' as the aligned positions of the clamping arm and gear are automatically incremented by the detent/s engaging in between said teeth. In this way, the number of meshing teeth relative to the range of movement of the clamping arm provide the accuracy of the coarse adjustment.

A lock may be provided (preferably in the form of a manually applied eccentric lock) in order to selectively restrict and free the gear.

The adjustment means may be hydraulic or purely mechanical and the clamp may be provided with in built interchangeability between hydraulic and mechanical action.

Many other advantageous features may be provided which should be readily discernible from the description of the drawings. These include the mounting of a clamping jaw of the clamping arm, a synchronised sliding and clamping of the clamping arm by way of a slide unit, a pack block stacking system, and particularised hydraulic cylinder arrangement design.

Further according to the present invention there is provided adjustable clamping apparatus comprising a body part mountable to a work table, said body part having a base and two parallel generally upstanding side walls embracing a clamping arm, mounted to pivot on the side walls, a screw being provided which extends through the clamping arm, said apparatus being provided with: a) a heel block mounted or mountable on the body part for co-operation with said screw to provide a pivotable adjustment for said clamping arm, b) said heel block being interchangeable with a hydraulic cylinder engageable with said screw for an alternative hydraulic clamping action of said arm.

The heel block/hydraulic cylinder may be conveniently mounted in a slot in the base.

Preferably, the clamping arm comprises a clamping part and an adjusting part with the screw extending through the adjusting part.

Further according to the present invention there is provided a slide unit for an adjustable clamp comprising an upper slidable part on which the clamp may be mounted, a hydraulic actuating cylinder of the unit being in hydraulic communication with a hydraulic link for connection to a hydraulic cylinder of the clamp to yield a substantially synchronised, timed or sequential sliding and clamping action of the clamp.

Further according to the present invention there is provided an adjustable clamp with a clamping arm and a spring mounted jaw being provided on the arm.

Further according to the present invention there is provided a pack block stacking system for a clamp, comprising one or more hollow pack blocks, one or more T-bollards with one or more bollard extensions, the or each bollard extension having an internal thread at one end to receive an associated one of the T-bollards and an external thread at its other end to engage in a further bollard extension or workable, said T-bollard and extension being dimensioned when threadably engaged together to extend all the way through a pack block to provide a strengthening tension member.

Further according to the present invention there is provided an adjustable clamp comprising a body part which is, in use, mountable to a worktable, a clamping arm being pivotally mounted on said body part, the pivotal movement of the arm relative to the body part (and relative in use to a workpiece on the worktable) being adjustable by adjusting means on said clamping arm to clamp a workpiece, and in which said clamping arm is of at least two part construction whereby the first of said at least two parts comprises a clamping part and the second of said at least two parts comprises an adjustment part, said first, clamping part being selectively releasable from and selectively lockable to said second, adjustment part thereby allowing said clamping part to be pivoted relative to the second part, in order to quickly position the clamping part relative to a workpiece before the clamping part is selectively locked to the adjustment part and the adjusting means operated to clamp the clamping part to the workpiece by way of said adjustment part, said clamp having one or both of the following features, a) locking means mounted on the pivotal axis of the arm which is axially movable in one direction along the pivotal axis to lock the clamping part and adjustment part together, and axially movable in the reverse direction to release said clamping and adjustment parts from one another and a spring loaded latch to operate the locking means to lock and release the clamping part to and from the adjustable part, b) locking means comprising a gear or spline which is movable into and out of intermeshing engagement with the arm to lock and release the clamping part to and from the adjustment part and a spring loaded latch to operate the locking means to lock and release the clamping part to and from the adjustment port.

In one embodiment of the present invention, the gear or spline has a central through bore receiving an anchor piece fixed to an end cap, and receiving an anchor piece fixed to the latch, the latch and its anchor piece preferably being rotatable about the axis of the central bore, said anchor pieces being held relative to one another by a tension spring. The latch may be pivotable about an axis generally at right angles to the axis of the central bore to engage and disengage the clamping part to/ from the adjustment part. The latch may be rotatable about the central bore axis to raise or lower the clamping part.

Preferably, the latch is mountable on either side of the clamp.

Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying diagrammatic drawings in which Figure 1 shows a sectional side view of one embodiment of an adjustable clamp in accordance with the present invention, with ringed sectional detail taken on line A-A; Figure 2 shows a plan view of the clamp, Fig. 1 being a section on line I-I of Fig. 2; Figure 3 shows a plan view of a clamp body part of the clamp; Figure 4 shows a perspective view of the clamp; Figure 5 shows a horizontally split sectional view taken on line V-V of Fig. 1; Figure 6 shows a rear view of the clamp looking in the direction of arrow B in Fig. 1 and incorporates a modification; Figure 7 shows a view similar to Fig. 1, but only partly in section, with the clamp mounted on a pack block;; Figure 8 shows in sectional orthographic projection, cyclic synchronised slide apparatus for the clamp, and the clamp is shown sketched in the sectional side elevational view; Figure 9 shows a perspective view of the slide apparatus; Figure 10 shows a detail; Figures 11 and 12 show modified clamps, Figure 13 shows a perspective view of a second embodiment of an adjustable clamp in accordance with the present invention, Figure 14 shows a view similar to Fig. 3 of a further embodiment of an adjustable clamp in accordance with the present invention, Figures 15 and 16 show a detail of a body locking screw of this latter embodiment; Figure 17 shows a further detail view, and Figures 18 to 22 show views of the first embodiment of the clamp but with a further modification.

Referring generally to Figs. 1 to 11, and more particularly to Figs. 1 and 4, an adjustable clamp 1 is provided with a body part 2 having a base 2a and two, parallel generally upstanding side walls 2b embracing a clamping arm 3, mounted on the side walls to pivot about horizontal axis X transverse of the side walls. The pivotal movement of the arm 3 relative to the body part 2 (and relative to a work table, not shown, on which the clamp may be mounted by means of T-bolt or bollard 4 engaging in key-hole slot 5 in base 2a) is adjustable by hydraulic adjusting means 6 on said clamping arm. The provision of the Tbolt and key-hole slot 4, 5 is believed to provide a most simple advantageous connection/disconnection of the clamp to/from a workpiece simply by downward and rearward movement of the body part 2 (or forward and upward movement for disconnection).The adjusting means 6 may be of any convenient form and may be entirely manual, for example a mechanical screw arrangement possibly of a type generally known per se. Figs. 4 and 7 show following the chain dotted lines, the range of pivotal movement of the clamping arm 3.

The clamping arm 3, in this instance is generally of laminated construction and comprises a first, clamping part 7 basically of three layers or laminations (see Fig. 4) formed from three similarly shaped plates 7a, 7b, 7c secured together, in this instance, by rivets 8.

The clamping arm 3 also comprises a second, adjustment part 9 comprised of two similarly shaped plates 9a, 9b arranged one on each side of clamping part 7, said plates 9a, 9b being of dissimilar shape to plates 7a, 7b, 7c.

The first, clamping part 7 is selectively releasable from and selectively lockable to said second, adjustment part 9, thereby allowing clamping part 7 to pivot about axis X relative to the adjustment part 9, by locking means in the form of a splined gear (or gear shaft) 10 aligned on the pivotal axis X. Gear 10 is rotatable about axis X and movable axially in direction A (see Figs. 2 and 5) along axis X to lock the clamping part 7 to the adjustment part 9 and movable axially in direction B along axis X to release or disengage the clamping part 7 from relative pivotal movement with the adjustment part 9.The splined gear 10 has external gear teeth T extending parallel to axis X for part of its length 10a (see Fig. 5) and these teeth are in intermeshing engagement with internal teeth T' on the clamping part 7 and are movable into and out of, intermeshing engagement with internal teeth T' on the adjusting part 9.

Fig. 5 shows a section taken on the line V-V of Fig. 1 and the upper half of Fig. 5 shows gear 10 in the'locking or engaged position whilst the lower half of the FIGURE shows the gear 10 in the released or disengaged position. Movement of gear 10 in direction B from the position shown in the upper half of Fig. 5 is limited by flange F which locates in recess 2c of one of the side walls 2b. This flange F may be provided by a circlip. Gear 10 is provided with one or more spring loaded detents, in the form of steel ball/s 11 loaded by helical compression spring/s 12, located in radial bores 13.

The central plate 7b of the clamping part 7 has a slightly larger diameter receiving hole P for gear 10 then the other plates 7a, 7c so that the ball or balls 11 seat in the groove G defined between plates 7a and 7c to positively axially locate the gear 10 relative to the clamping arm 3 in the locking or engaged position in a manner which should be evident from Fig. 5. Plate 7b does not have any internal gear teeth.

When the gear 10 is engaged to lock the clamping part 7 and adjusting part 9 of the arm 3 together (see upper half of Fig. 5) teeth T on the gear intermesh with teeth T' on plates 7a, 7c of the clamping part 7 and also intermesh with teeth T' on plates 9a, 9b of the adjustment part 9; one set of teeth T on gear 10 locks plate 9a of the adjustment part to plate 7a of the clamping part and the other set locks plate 7c of the clamping part to plate 9b of the adjustment part. When the locking engagement is released by moving gear 10 in direction B, see lower half of Fig.

5, the clamping part 7 is free to pivot relative to the adjustment part 9, but the gear 10 is in intermeshing engagement with part 7 via gear teeth T and the internal teeth T' on plate 7c.

The or each ball 11 rides on the internal teeth T' of plate 9b which acts as a self-alignment means that automatically aligns clamping part 7, adjustment part 9 and gear 10 prior to operation (axial movement) of gear 10 to lock the clamping part 7 to the adjustment part 9; this is because once the clamping part 7 has been released from the adjustment part 9 and pivoted relative to part 9, on subsequent release of the clamping part 7, the or each spring loaded ball 11 automatically seats in the bottom of a gear tooth recess to rotate the gear 10 a small amount about axis X relative to plate 9b until the teeth T, T' on gear 10 and adjustment part 9 are precisely positioned for intermeshing engagement on axial advancement of gear 10 in direction A without any manual trial and error relative rotation having to be effected before the locking means can be operated.

Therefore, the or each spring loaded ball 11 provides both an axial indication of engagement of the gear 10 relative to arm 3, in the locking position and an automatic radial or angular self-alignment or synchromesh in the released position. As the or each ball 11 rides on the gear teeth T' on plate 9b a 'clicking' sound is audible as the 11 rides on the peaks and troughs of the teeth T', which helps the user in relative positioning of the clamping part 7 and in realising that the self-alignment is provided. The provision of such selfalignment means has obvious advantages from the point of view of ease of operation of the device and from the point of view of reduced wear of the co-operating parts.

To restrain possible axial movement of gear 10 relative to the arm 3 and body part 2 (while the clamping part 7 is locked to adjustment part 9) a manually applied eccentric lock 14 (camlock stud) may be provided as shown in Fig. 7, which lock 14 is pivotable about axis Y into and out of overlapping relation with gear 10 in order to selectively restrict and free the gear 10 for axial movement thereof in direction B. The lock 14 may be of any convenient form and may possibly be spring- loaded or to some extent automatically, rather than manually, applied.

Fig. 6 shows a somewhat modified rear view of the clamp 1 in which the circlip flange F has been replaced by alternative arrangement in the form of a shoulder screw 15 in a manner which should be self-evident.

Once the clamping part 7 is able to pivot relative to the adjustment part 9, advantageously, a quick coarse adjustment of part 7 relative to a workpiece (not shown) to be held by the clamp 1 on a worktable (not shown) may be effected simply by manually moving part 7. The workpiece will be placed on a horizontal surface below the clamping jaw 16 (pivotable about axis 17-see Fig. 1, and particularly the sectional ringed detail) and part 7 may be pivoted relative to part 9 and the body part 2 until the jaw 16 is almost in its required clamping position possible spaced at a small distance from the workpiece. The accuracy of the coarse adjustment will depend upon the gear teeth T, T' and in general on the number of incremented mating tooth positions provided in the range of movement of clamping part 7.In the present case the coarse adjustment should be accurate to within 9" or 10 of any required clamping position throughout the whole of its range of clamping positions; before clamping part 7 is locked to the adjustment part 9 a finer adjustment of the clamping position can be effected by adjusting means 6, to finally clamp the workpiece in the required position.

Additionally, the workpiece can be quickly released, after removal of clamping load merely by appropriate axial movement of the gear 10 to release the clamping part 7. The clamping part 7 may then be rotated through the required angle so that the workpiece can be removed from the worktable; advantageously in this respect the clamping part 7 can be raised to a substantially vertical position so that it does not protrude horizontally beyond the body part 2, in a direction towards the workpiece. This enables the workpiece to be lifted vertically by any required amount.

As shown in the ringed detail in Fig. 1 (taken on line A-A the free end of the centre plate 7b of clamping part 7 has been cut away to provide a 'spring in' or friction fit for jaw pad 18 into the free end of part 7, and the jaw 16 is secured to the arm by way of nut and bolt 19. This effectively means that jaw 16 does not rotate freely and loosely about axis 17, since this is thought to be disadvantageous in some instances, and instead advantageous resilience is provided so that the jaw effectively remains in a particular angular location until moved therefrom allowing a setting angle of the jaw to be achieved.

Alternatively, one or more spring washers (wavy washers) could be mounted on pivoted axis 17 in between the jaw 16 and part 7 in a manner which should readily be envisaged to provide a comparative function. It is particularly advantageous to be able to set the angle of the clamping jaw where a series of clamps are hydraulically activated to clamp similar workpieces.

A tension spring arrangement 20 is provided, mounted between the adjusting part 9 of the clamping arm 3 and the lower part of side walls 2b (or alternatively between adjusting part 9 and base 2a).

The hydraulic adjustment means 6 comprises a threaded screw 21 with hexagon head 21a and a part-conical spanner engagement extension 21b. Screw 21 has a larger diameter stop portion 21c under head 21a.

The threaded portion of screw 21 passes through a trunnion block 22 supported between plates 9a and 9b and, more specifically, threadably engages with a collar 23 of nylon or the like inset in the upper part of trunnion block 22 to provide a stiff thread engagement. The lower unthreaded end of screw 21 has a radiused end and passes into a deep bore b in generally vertically reciprocatable piston P' of a hydraulic cylinder H.C.

which is connectable to a hydraulic fluid source via piping 24 and pipe connection 25 in a manner which should be readily discernible from the drawings.

A plan view detail of the hydraulic cylinder and heel plate 26 is shown in Fig. 10, which more clearly shows how the hydraulic cylinder is fitted onto the body part 2 by means of the heel plate 26 and countersunk screw 27 (to maintain position only).

A swarf exclusion washer W (made, for example, from plastics or metal) is provided which surrounds bolt 21 at the top of deep bore 6. The hydraulic cylinder H.C. is of new design and particularly advantageous in the present instance, since it also provides for the load to be taken from the bottom of the piston, rather than from the top as in other designs (see Figs. 11 and 12). Taking the load from the bottom of the piston in this manner yields strong self aligning characteristics of the adjustment means 6 and reduces any tendency for distortion or tilting. Providing a cylinder of relatively small size and stroke (about 12mm) also reduces such a tendency. The hydraulic cylinder pressure will probably be in the order of 250 bar.

Fig. 3 is a plan view of the body part 2 showing the hydraulic cylinder location L. In fact the clamp may be modified for different hydraulic cylinders (some examples of which are shown in Figs. 11 and 12). The tension spring arrangement 20 may also be modified as shown at 20' in Figs 11 and 12.

The present invention extends to the provision of a clamp 1 with- interchangeable adjusting means and more specifically to interchangeable purely mechanical and hydraulic adjusting means. In this respect Fig. 7 shows an interchangeable heel block 28 which may be used for the non-hydraulic version. It is a relatively simple matter to slip out the hydraulic cylinder H.C. with its piston P' from the rear location slot L and replace same with a heel block of appropriate dimensions to accept the end of the screw 21. The cost of producing a hydraulic clamp is relatively high and so providing such simple means for conversion to/from hydraulic adjustment in said manner allows a good choice for the user, so that the same clamp can be upgraded to hydraulic operation quite easily at a later date if required.

In the purely mechanical mode the screw 21 can be operated merely by using a spanner tool on the hexagon head 21a, with the screw engaging in the heel block. Where hydraulic operation is provided, in general a plurality of clamps are, preferably, linked up to the same hydraulic suppiy so that clamps can be operated together to clamp workpieces simultaneously if required yielding an automatic or at least semi-automatic clamping process.

The present invention also extends to an advantageous system of connecting the clamp 1 onto one or more pack blocks connected to the worktable (see Fig. 7) and also to a cyclic or synchronised slide unit for use with the clamp 1 (see Figs. 8 and 9).

Fig. 7 shows the T-bolt or bollard 4 with bollard extension 29 believed to be a unique arrangement for fixing the pack block 30 to the clamp 1 and worktable.

The T-bollard 4 screws into one end of bollard extension 29, which passes all the way through the hollow, aluminium pack block 30 and is itself provided with a threaded end engageable into another bollard extension (not shown), if a further pack block is to be used to raise the clamp 1 still further, or, alternatively as shown, said threaded end may be engaged into the upper part 31 of the worktable. The bollard extensions 29 provide steel tension members giving a seemingly much more stable stacking arrangement than previously achieved whilst'using hollow blocks.

Figs. 8 and 9 show a cyclic or synchronised slide unit 32 which is hydraulically operated to slide the clamp 1 forwards and backwards in timed relation relative to the worktable and to a workpiece in a manner to be described. The bollard 4 is used to secure the clamp 1 to the slide unit 32 as shown, the threaded end thereof engaging in hole 33a (see Fig. 9) in the upper slidable part 33 of unit 32. The unit 32 is secured to the worktable itself by way of threaded bolt 34 passing through the lower part 36 of unit 32 into the worktable. As should be evident from Figs. 8 and 9 the upper siidable part 33 (which extends over and around the sides of the lower part 36) is shown in the fully extended position relative to lower part 36 and may be retracted to the position shown in chain dotted lines in Fig. 9.

As shown in the sectional end view taken on line B-B in Fig. 8 the lower part 36 is generally T-shaped for a portion of its length and mates with a generally U-shaped portion of said upper slidable part 33.

The slide unit 32 has a main hydraulic cylinder 37 with piston 38 shown in the extended position. The piston 38 acts directly on pin 39 which extends downwardly from upper part 33 and which pin 39 is horizontally reciprocatable in a longitudinal slot 40 in lower part 36. The ends of the slot 40 govern the stroke of the upper part 33 of the slide unit 32 to which the clamp 1 is attached. A return action tension spring 41 is also positioned as shown to return the upper part 33 to its retracted position on cessation of hydraulic pressure. The slide unit 32 therefore allows a horizontal movement of the whole clamp 1 relative to a workpiece and worktable to enable a workpiece to be clamped more quickly and more easily and to allow a quick release of the workpiece with the clamp being mov able right out of the way, giving greater ac cessibility to the workpiece for removal from the table.

Most importantly this particular slide unit 32 provides an extra facility since it allows auto matic synchronisation between the horizontal slide action previously described and clamping action of the clamping arm 3. As best shown in the lower sectional plan view of the unit 32 in Fig. 8, the hydraulic feed for the combined clamp 1 and slide unit 32 is supplied to the union on the end of cylinder 37. Hydraulic link 44 is connected via hydraulic piping to hydraulic cylinder HC. The hydraulic link 44 is connected to cylinder 37 by two passages 42 and 43; passage 43 incorporates a non-return valve.The passage 42 provides that once the slide unit 32 has been moved to its extended position, the end of the piston 38 remote from pin 39 passes and thereby opens it allowing hydraulic pressure to be applied to the clamping cylinder HC via link 44 to thereby automatically pivot the arm 3 to clamp a workpiece. Upon removal of the hydraulic pressure arm 3 is lifted from the workpiece by the action of the spring arrangement 20 and the hydraulic fluid is returned to the reservoir (not shown) via link 44, passage 43 and its non-return valve. When the pressure in cylinder 37 drops sufficiently slide 33 retracts under the action of spring 41 to clear the jaw 16 from the workpiece.

Fig. 13 shows another embodiment of an adjustable clamp 1'. As shown the clamp 1' has a two part clamping arm 3' and clamping part 7' is offset completely to one side of adjusting part 9'. The clamping part 7' and adjusting part 9' are not laminated. In fact this embodiment represents an earlier stage in development of the clamp basically shown in Figs. 1 to 10. In this instance the locking means is provided by axially movable toothed gear 10' such that in one axial position (the gear 10' projecting from body part 2') internal teeth on the part 7' mesh with external teeth (splines) on the gear 10' but the gear 10' does not extend axially within part 9' so that the part 7' and gear 10' can pivot relative to the part 9'.In the locking position as shown in Fig. 13 the teeth on gear 10 also mesh with internal teeth on the adjusting part 9' so that the part 7' only pivots with the part 9'.

Fig. 14 shows a view of a further, preferred embodiment of an adjustable clamp similar to Fig. 3. In this instance the clamp body part X' has a plain slot Y' which open at one end, rather than a key-hole slot. This is advantageous since the connection of the clamp to a workpiece can be done simply by forward movement of the body part X' (or rearward movement for disconnection). This arrangement is preferred since a forward movement for disconnection could in some instances by inconvenient if the workpiece is in the path of required forward movement of the clamp body part X'.

Figs. 15 and 16 show details of a body locking screw Z. Fig. 15 corresponds in similar fashion to an outside view of the left bottom corner portion of Fig. 1 and Fig. 6 is an underneath view of the screw Z. Adjustment of the body locking screw Z enables the clamp to be either: 1) free to be slid on and off the bollard; (2) free to rotate about the bollard but prevented from sliding off; or (3) locked both against sliding and rotation relative to the bollard. The body locking screw is, therefore, an advantageous feature which may be individually patentable.

Fig. 17 shows a plan view detail similar to the right hand end of Fig. 2 in which part 22' is now round rather than square in cross section.

Figs. 18 to 22 shows a further modification to the clamp as shown generally in Figs. 1 to 11. Figs. 18 and 19 are views similar to Fig.

5 with Fig. 18 representing the "unlocked" position and Fig. 19 representing the "locked" position. Figs. 20 and 21 are inverted plan views of Figs. 18 and 19 respectively and Fig.

22 is a view looking in the direction of arrow Z in Fig. 19.

The modification in this instance is basically the provision of latch 100 which is pivotable about vertical axis 101 provided by pin 102 in a manner which should generally be self-evident from the drawings. Latch 100 is spring loaded by means of close wound tension spring 103 and operates the locking means (gear or spline 10) to lock and release clamping part 7 to and from adjustment part 9, from one side of the clamp. Through a quarter turn of the latch about axis 101, gear 10 is moved to fully engage and disengage the clamping part 7 to and from adjustment part 9 in a way which renders partiai engagement difficult and in a way which indicates clearly whether the part 7 is engaged or disengaged.

Figs. 18 and 19 show an end cap 104, which can be of any convenient shape and onto which is fixed non-rotatably thereto a central anchor piece 105 extending about halfway within an axial through bore 106 in gear 10. The latch is fixed to an axially pivotable anchor piece 107 by way of pin 102 and also extends within bore 106 up to about halfway therealong into contact with anchor piece 105 as shown in Fig. 18. The anchor pieces 105, 107 are held relative to one another by the spring 103, the ends of the spring being fixed relative to the respective anchor piece by engagement over an enlarged threaded portion of the respective anchor piece.

Unlike the first described embodiment, advantageously an internal grease nipple 108 is provided.

On lifting the latch 100 from the position shown in Figs. 19 and 21 the spring 103 (in a tensioned state) pulls the gear 10 to the left (see Fig. 18) to disengage the clamping part 7 from the adjustment part 9 (see Fig. 20). Additionally, and most importantly clamping part 7a is still splined to the gear 10 so that rotation of the latch 100 about the axis of bore 103 (rather than about pin 102) is possible and may be utilised to raise or lower clamping part 7 click by click on the spring loaded ball 11. The ball 11 is mounted in the gear 10 in a bore 109 which is plugged at the bottom to seat spring 12. Oil may enter bore 109 via bore 106 and grease nipple 108. Gear 10 is mounted in bush 110.

The adjustment part 9 is engaged to clamping part 7 merely by pivoting latch 100 about axis 101 to the position shown in Figs. 19 and 21, thereby extending spring 103 urging all the mating splines into engagement. The latch provides a safe positive engagement of the locking means and it can be seen immediately whether or not the locking means is being applied.

If desired the latch can be repositioned on the other side of the clamp, by the inclusion of bush 110. This can be done by loosening set screw 111 and lifting latch 100 until spring anchors 105, 107 meet. Pivot pin 102 is removed and the entire gear 10 with end cap 104 can be removed to the left (see Fig.

18). Bush 110 may then be repositioned on the other side of the clamp and the clamp reassembled in reverse order.

Similarly the rotational alignment of the latch to the clamp arm may be changed.

In short the benefits offered by this new arrangement are: 1) The clamp can be fully operated without necessitating the operator having to place his hands into the work area.

2) A positive indication is provided to enable the operator to clearly see whether or not the clamping part is engaged with the adjustment part.

3) The latch is easily repositioned on the other side of the clamp and the rotational position of the latch may easily be changed.

It is believed that the present invention introduces many new concepts and individual features thereof and/or functions appertaining thereto may be individually patentably inventive and/or combination thereof may be individually patentably inventive. Some important features of the present invention relate to the at least two part clamping arm, a manually operated swing back facility to clear the workpiece, a finer 'coarse' adjustment facility, syncromesh facility, a clamp slide unit and such a slide unit having sequential, synchronised or timed operation with clamping action of the clamping arm, the provision of interchangeable hydraulic adjustment arrangements between themselves and/or with a mechanical arrangement such as a screw, improved characteristics in relation to the clamping jaw and method of engaging the clamp to a worktable, as well as an improved stacking pack block system and spring loaded latch for the locking means.

Stiil further according to the present invention there is provided an adjustable clamp comprising a body part which is, in use, mountable to a worktable, a clamping arm being pivotally mounted on said body part, the pivotal movement of the arm relative to the body part (and relative in use to a workpiece on the worktable) being finely adjustable by adjusting means on said clamping arm to clamp a workpiece, the clamping arm comprising a first part releasably lockable to a second part and pivotable relative thereto in the released condition to allow a quick, coarse adjustment of the arm in relation to a workpiece, and a quick swing back facility to rapidly clear the workpiece, said clamp having one or more of the following features:: a). locking means mounted on the pivotal axis of the arm which is axially movable in one direction along the pivotal axis to lock the first part to the second part and axially movable in the reverse direction to release the first and second parts for relative pivotal movement, b). locking means comprising a gear which is movable into and out of meshing engagement with the arm to lock and release the first and second parts, c). the first part being pivotable relative to the second part, in the released condition, to allow a coarse adjustment to within about 9" or 11" of any required clamping position throughout the whole range of clamping positions of the arm, d). locking means to lock the first part to the second part and self-alignment means which automatically aligns the first and second part with the locking means prior to operation of the locking means to lock the first part to the second part, e). ability of the clamping arm to be swung up clear of the workpiece to allow its easy vertical removal.

Claims (31)

1. An adjustable clamp comprising a body part which is, in use, mountable to a worktable, a clamping arm being pivotally mounted on said body part, the pivotal movement of the arm relative to the body part (and relative in use to a workpiece on the worktable) being adjustable by adjusting means on said clamping arm to clamp a workpiece, and in which said clamping arm is of at least two part construction whereby the first of said at least two parts comprises a clamping part and the second of said at least two parts comprises an adjustment part, said first, clamping part being selectively releasable from and selectively lockable to said second, adjustment part thereby allowing said clamping part to be pivoted relative to the second part, in order to quickly position the clamping part relative to a workpiece before the clamping part is selectively locked to the adjustment part and the adjusting means operated to clamp the clamping part to the workpiece by way of said adjustment part, said clamp having one or more of the following features, a) locking means mounted on the pivotal axis of the arm which is axially movable in one direction along the pivotal axis to lock the clamping part and adjustment part together, and axially movable in the reverse direction to release said clamping and adjustment parts from one another, b) locking means comprising a gear or spline which is movable into and out of intermeshing engagement with the arm to lock and release the clamping part to and from the adjustment part, c) the arrangement being such that the clamping part is pivotable to within a coarse adjustment of about 9" to 11" of any required clamping position throughout the whole range of clamping positions before being locked to the adjustment part when a finer adjustment of the clamping position can be effected by said adjusting means, d) locking means to lock the clamping part to the adjustment part and self-alignment means which automatically aligns the clamping part, adjustment part and locking means prior to operation of the locking means to lock said clamping part to the adjustment part, e) locking means to lock the clamping part to the adjustment part such that when released it allows the clamping part to be swung upwards to give clearance for the workpiece to be removed in a generally vertical direction.

2. A clamp as claimed in Claim 1 in which the clamping part is of laminated form.

3. A clamp as claimed in Claim 2 in which the clamping part comprises three plates fixed together.

4. A clamp as claimed in any one of the preceding claims in which the adjustment part comprises two plates arranged one on each side of the clamping part.

5. A clamp as claimed in any one of the preceding claims in which, locking means, or the locking means, comprises an axially movable toothed gear or spline which pivots with the clamping part relative to the adjustment part for coarse adjustment, the gear, clamping part and adjustment part meshing together during clamping.

6. A clamp as claimed in Claim 5 when dependent from Claim 3 in which the central plate is toothless and has a slightly larger diameter receiving hole for the gear than the other plates of the clamping part

7. A clamp as claimed in Claim 6 in which the gear (locking means) is provided with one or more spring loaded detents (preferably in the form of balls) located in radial bores in the gear.

8. A clamp as claimed in Claim 7 in which the spring loaded detent/s act to align the clamping part, adjustment part and gear, along the gear axis, whilst the clamping part is locked to the adjustment part, by being located on the central plate in between gear teeth on the other two plates of the clamping part (and thus in a circumferential groove formed in between these two plates).

9. A clamp as claimed in Claim 7 or Claim 8 in which the detent or detents may provide an automatic radial or angular self-alignment or syncromesh of the gear (locking gear) relative to the clamping arm in the released position i.e. during coarse adjustment of the clamping part before operation (axial movement) of the gear (locking means) to lock the clamping part to the adjustment part.

10. A clamp as claimed in Claim 9 in which in the released position the detent/s ride on internal teeth on one of the plates of the adjustment part yielding an audible 'clicking' as the aligned positions of the clamping arm and gear are automatically incremented by the detent/s engaging in between said teeth.

11. A clamp as claimed in any one of the preceding claims in which a lock is provided in order to selectively restrict and free the gear.

12. A clamp as claimed in Claim 11 in which the lock is in the form of a manually applied eccentric lock.

13. A clamp as claimed in any one of the preceding claims in which the adjustment means is hydraulic or purely mechanical.

14. A clamp as claimed in any one of the preceding claims provided with in built interchangeability between hydraulic and mechanical action.

15. A clamp as claimed in any one of the preceding claims having a spring mounted jaw on the clamping arm.

16. A clamp as claimed in any one of the preceding claims having synchronised, timed or sequential sliding and clamping of the clamping arm by way of a slide unit.

17. A clamp as claimed in any one of the preceding claims having a pack block stacking system.

18. An ajustable clamping apparatus comprising a body part mountable to a work table, said body part having a base and two parallel generally upstanding side walls embracing a clamping arm, mounted to pivot on the side walls, a screw being provided which extends through the clamping arm, said apparatus being provided with: a) a heel block mounted or mountable on the body part for co-operation with said screw to provide a pivotable adjustment for said clamping arm, b) said heel block being interchangeable with a hydraulic cylinder engageable with said screw for an alternative hydraulic clamping action of said arm.

19. Apparatus as claimed in Claim 18 in which the heel block/hydraulic cylinder is mounted in a slot in the base.

20. Apparatus as claimed in Claim 18 or 19 in which the clamping arm comprises a clamping part and an adjusting part with the screw extending through the adjusting part.

21. A slide unit for an adjustable clamp comprising an upper slidable part on which the clamp may be mounted, a hydraulic actuating cylinder of the unit being in hydraulic communication with a hydraulic link for connection to a hydraulic cylinder of the clamp to yield a substantially synchronised, timed or sequential sliding and clamping action of the clamp.

22. An adjustable clamp with a clamping arm and a spring mounted jaw being provided on the arm.

23. A pack block stacking system for a clamp, comprising one or more hollow pack blocks, one or more T-bollards with one or more bollard extensions, the or each bollard extension having an internal thread at one end to receive an associated one of the T-bollards and an external thread at its other end to engage in a further bollard extension or worktable, said T-bollard and extension being dimensioned when threadably engaged together to extend all the way through a pack block to provide a strengthening tension member.

24. An adjustable clamp comprising a body part which is, in use, mountable to a worktable, a clamping arm being pivotally mounted on said body part, the pivotal movement of the arm relative to the body part (and relative in use to a workpiece on the worktable) being finely adjustable by adjusting means on said clamping arm to clamp a workpiece, the clamping arm comprising a first part releasably lockable to a second part and pivotable relative thereto in the released condition to allow a quick coarse adjustment of the arm in relation to a workpiece, and a quick swing back facility to rapidly clear the workpiece, said clamp having one or more of the following features:: a) locking means mounted on the pivotal axis of the arm which is axially movable in one direction along the pivotal axis to lock the first part to the second part and axially movable in the reverse direction to release the first and second parts for relative pivotal movement; b) locking means comprising a gear which is movable into and out of meshing engagement with the arm to lock and release the first and second parts; c) the first part being pivotable relative to the second part, in the released condition, to allow a coarse adjustment to within about 9" or 11" of any required clamping position throughout the whole range of clamping positions of the arm;; d) locking means to lock the first part to the second part and self-alignment means which automatically aligns the first and second part with the locking means prior to operation of the locking means to lock the first part to the second part; e) ability of the clamping arm to be swung up clear of the workpiece to allow its easy vertical removal.

25. An adjustable clamp comprising a body part which is, in use, mountable to a worktable, a clamping arm being pivotally mounted on said body part, the pivotal movement of the arm relative to the body part (and relative in use to a workpiece on the worktable) being adjustable by adjusting means on said clamping arm to clamp a workpiece, and in which said clamping arm is of at least two part construction whereby the first of said at least two parts comprises a clamping part and the second of said at least two parts comprises an adjustment part, said first, clamping part being selectively releasable from and selectively lockable to said second, adjustment part thereby allowing said clamping part to be pivoted relative to the second part, in order to quickly position the clamping part relative to a workpiece before the clamping part is selectively locked to the adjustment part and the adjusting means operated to clamp the clamping part to the workpiece by way of said adjustment part, said clamp having one or both of the following features, a) locking means mounted on the pivotal axis of the arm which is axially movable in one direction along the pivotal axis to lock the clamping part and adjustment part together, and axially movable in the reverse direction to release said clamping and adjustment parts from one another and a spring loaded latch to operate the locking means to lock and release the clamping part to and from the adjusting part, b) locking means comprising a gear or spline which is movable into and out of intermeshing engagement with the arm to lock and release the clamping part to and from the adjustment part and a spring loaded latch to operate the locking means to lock and release the clamping part to and from the adjustment part.

26. A clamp as claimed in Claim 25 in which the gear or spline has a central through bore receiving an anchor piece fixed to an end cap and receiving an anchor piece fixed to the latch and preferably rotatabie therewith about the axis of the central bore, said anchor pieces being held relative to one another by a tension spring.

27. A clamp as claimed in Claim 25 in which the latch is pivotable about an axis generally at right angles to the axis of the central bore to engage and disengage the clamping part to/from the adjustment part.

28. A clamp as claimed in any one of Claims 25 to 27 in which the latch is mountable on either side of the clamp.

29. A clamp substantially as herein described with reference to Figs. 1 to 10, or 11, or 12, or 13, or 14 to 17 or 19 to 22 of the accompanying drawings.

30. A slide unit as claimed in Claim 21 and substantially as herein described with reference to Fig. 8 and 9 of the accompanying drawings.

31. A pack block stacking system as claimed in Claim 23 and substantially as herein described with reference to Fig. 7 of the accompanying drawings.