GB2071534A - Clamp apparatus - Google Patents

Abstract

A work table 10, includes four spaced-apart jaw assemblies arranged in opposed pairs 11, 12 and 13, 14, a first pair 11, 12 each having, a jaw head 15 comprising two jaws 20, 21 and a second pair 13, 14 each having a jaw head 15 comprising four jaws 22, 23, 24, 25. By means of a respective threaded rod 18 each jaw assembly 11 to 14 can be radially adjusted along a respective channel 16 to contact a workpiece whereupon its jaws can be locked in position by an actuating cylinder 31, 45 of associated clamping means. Recesses 58 are provided on the table 10 between adjacent jaw assemblies 11, 12, 13, 14, to accommodate a respective jack 54, each jack 54 comprising a pivotal arm 55 which by means of a respective threaded rod 59 can be swung upwards to engage the workpiece from underneath. <IMAGE>

Description

SPECIFICATION Clamp apparatus This invention concerns clamp apparatus for holding a workpiece, such as rough casting.

With known clamp apparatus it is difficult to manipulate the workpiece so that it may securely clamped in any desired position, more particularly into a position which allows the removal of the maximum amount of excess material from the workpiece, for example, by cutting, so that subsequently said workpiece needs only a minimum amount of finish machining.

An object of the invention is to provide a clamp apparatus which facilitates the clamping of a workpiece into any desired clamped position.

With this object in view the present invention provides a clamp apparatus comprising a support body for receiving a workpiece, there being, on said support body, spaced-apart jaw assemblies each of which comprises at least two jaws individually extensible to enable the workpiece to be clamped.

Preferably each jaw assembly is adjustably mounted on the support body and is in the form of a respective jaw head in which the respective jaws are slidable.

Preferably there are four jaw heads on the support body, arranged in opposed pairs, with one of the opposed pairs disposed at a right angle to the other opposed pair.

Each jaw head may have either two jaws or four jaws. Preferably, the respective jaw heads of one opposed pair each have two jaws and the respective jaw heads of the other opposed pair each have four jaws.

Each jaw head preferably comprises clamping means to enable the respective jaws to be locked in their respective adjusted positions.

Where the jaw head has four jaws the clamping means may be arranged at one side of the jaw head.

If the jaw head only has two jaws then the clamping means can be arranged on said jaw head's underside.

Advantageously, the clamping means comprises a cylinder having a hollow piston and a hollow ram and a stud which extends through the cylinder and slidably mounts the piston and the ram, the stud having slidably mounted thereon a mounting block to which is secured a pair of pressure plates for pressing against the upper and lower pairs of jaws respectively.

One or more jacks may also be provided on the support body, each said jack being removably locatable thereon so as to be disposed between a respective adjacnet pair of the jaw heads.

Advantageously each of the jacks comprises a pivotal arm which is adjustable to provide support for a workpiece from underneath.

Each jack preferably comprises actuating means comprising a threaded rod extending through a block and a pair of link rods pivotally connected to the block and to the pivotable arm, the block being adjustable along the threaded rod to enable the pivotal arm to be swung upwardly to support the workpiece.

The support body may be provided with respective recesses to accommodate the actuating means of each of the jacks.

Preferably a removable mounting plate is engagable in a fixed location on the support body to provide pivotal connections for one end of each of the pivotal arms so that each said arm can be swung upwards, away from the support body, to enable it to support the workpiece.

Advantageously the support body is a table.

The invention will be described further, by way of example, with reference to the accompanying drawings, it being understood that the following description is illustrative, and not restrictive, of the scope of the invention.

In the drawings: Fig. 1 is a plan view of a preferred embodiment of the clamp apparatus of the invention; Fig. 2 is an enlarged, part cross-sectional view of a jaw assembly mounted on a support body, part of which is shown, both the jaw assembly and the support body forming part of the clamp apparatus shown in Fig. 1; Fig. 3 is an enlarged side view of the jaw assembly and support body shown in Fig. 2; Fig. 4 is a view similar to that shown in Fig. 3 but illustrating a modified form of the jaw assembly; Fig. 5 is a side view of a modified jaw which can be used in the jaw assemblies of Figs. 2 to 4; Fig. 6 is an enlarged plan view of a jack which forms part of the clamp apparatus of Figs. 1 to 5, the jack being shown mounted on the support body; and Fig. 7 is an enlarged side view of the jack and the support body of Fig. 6.

The preferred embodiment of the clamping apparatus of the invention as illustrated in the drawings comprises a support body, in the form of an octagonally-shaped table 10, made of any suitable material such as mild steel, for the reception of a workpiece (not shown), for example a casting from which it is desired to remove excess material. Mounted on the table 10 are four spaced-apart jaw assemblies 1 1, 12, 13 and 14, for the clamping therebetween of the workpiece, each said jaw assembly comprising a box-like jaw head 15. The jaw head 15 illustrated in Figs. 2 and 3 comprises top and bottom plates, 79 and 80 respectively, two side plates 81 and 82, a substantially T-shaped end plate 83 and two end plates 84, 85. The various plates are secured together by screws 86. These plates may be made of the same material as the table 10.The table 10 has four dove-tail slots or channels 1 6 for location of the respective jaw heads 1 5 by a complementary drove-tail-shaped block 18 on the bottom of the jaw head 1 5 projecting downwards into the respective channel 16. These channels 1 6 radiate from the centre of the table 10 at 900 spacings. Each jaw head 15 is adjustable along its respective channel 16, towards and away from the table's centre, by means of a respective threaded rod 18 which is mounted within the thickness of the table 10 so as to extend longitudinally along a respective channel 16 and through the block 17 of a respective jaw head 15. Form integrally with one end of each threaded rod 18 is a square-sectioned extension 19 by which the threaded rod 18 can be rotated by a suitable tool (not shown).

The jaw heads 15 are arranged on the table 10 in two opposed pairs one opposed pair of jaw heads 1 5 being formed by jaw assemblies 11, 12 and the other opposed pair being formed by jaw assemblies 13, 14. The arrangement of the jaw heads 1 5 is such that each jaw head 1 5 of one opposed pair 11, 12 has two jaws 20,21 and each jaw head 1 5 of the other opposed pair 13, 14 has four jaws 22,23 24, 25. In the two-jaw jaw heads 1 5 the jaws 20, 21 are arranged one above another. In the four jaw jaw heads 1 5 is the jaws 22, 23, 24, 25 are in pairs, the pair of jaws 22, 23 being arranged above the pair of jaws 24, 25.

Each jaw 20 to 25 comprises an elongate, rectangularly-sectioned bar 26 which extends horizontally through and is slidable in a respective correspondingly-shaped hole in the jaw head 15.

The length of the bar 26 is such that a portion can protrude from the jaw head 15 towards the centre of the table 1 0. The bar 26 ensures that each respective jaw 20 to 25 is individually slidable in its respective jaw head 15 and this sliding movement is facilitated by a knob 27, secured to the outer end 28 (i.e. the end away from the centre of the table) of the bar 26, which knob 27 can be grasped for sliding the bar 26 and hence a respective jaw 20 to 25 back and forth manually in its respective jaw head 15. The inner end 29 of each bar 26, which end 29, inuse, is directed towards the workpiece and serves to clamp the workpiece, is provided with a protruding pad 30 made of a suitably resilient material.

After a workpiece has been deposited on the table 10, and each jaw 20 to 25 has been adjusted to locate it in a desired position, clamping means provided on each jaw head 15 are operated to lock each jaw 20 to 25 in its respective adjusted position.

The clamping means comprises, for each jaw head 15 having the four jaws as illustrated in Figs.

2 and 3, a cylinder 3, either hydrualically or pneumatically operated, having a hollow piston 32 and a hollow ram 33, a stud 34 extending through the cylinder 31 so that the piston 32 and the ram 33 are slidable thereon and being secured by one of its ends 35, which is threaded to the jaw head 1 5. The stud 34 also has a thread at its other end 36 for receiving a nut 37 so that the cylinder 31 can be secured to the stud 34.

Mounted on the stud 34, between its end 35 which is secured to the jaw head 15 and the cylinder 31, so as to extend vertically between upper pair of jaws 22, 23 and lower pair of jaws 24, 25, is a substantially rectangular mounting body 38. The mounting body 38 mounts a pair of rectangular pressure plates 39, each of which pressure plates 39 has a pair of spaced-apart brackets 40 between which by means of a respective pin 41 is secured a respective end of the mounting body 38.

The pressure plates 39 extend longitudinally of the upper pair of jaws 22, 23 and the lower pair of jaws 24, 25 respectively.

The jaws of both the upper pair of jaws 22, 23 and lower pair of jaws 24, 25 each have friction pads 42 on two longitudinal sides and are separated from one another by a rectangular spacer 43. Therefore, each pair of jaws 22, 23 and 24, 25 forms part of a sandwich arrangement comprising jaw, spacer and jaw.

To lock each jaw of the upper pair 22. 23 and the lower pair 24, 25, the piston 32 is actuated to force the ram 33 against the mounting body 38 which, in turn, is moved along the stud 34 until a respective pressure plate 39 presses against a respective friction pad 42 of a respective jaw 23 and 25. The jaw 23 or 25, of course, presses, by means of the remaining friction pads 42 and the spacer 43, the other jaw 24 or 25 against the jaw head's interior surface, so locking both pairs of jaws 22, 23 and 24, 25.

The clamping means described above is, as previously mentioned, for a jaw head 15 having four jaws, 22 to 25 and can be arranged so that its cylinder 31 protrudes at one side of the respective jaw head 15.

The jaw assemblies 11 and 12 comprises twojaw heads 15, where the two jaws 20, 21 are disposed one above the other, and as can be more clearly seen in Fig. 4 the clamping means is arranged so that its ram 44 protrudes from its piston 45 at the underside of the jaw head 1 5. In this arrangement, which is either hydraulically or pneumatically operated, the clamping means does not have a mounting body. Instead the ram 44 acts on a loose spacer 46 disposed between the ram 44 and the lower jaw 21 of the two jaws 20, 21 of the pair. Like the jaws 22 to 25 each jaw 20, 21 also comprises an elongate rectangular bar 47 which extends horizontally through, and is slidable in, a respective correspondingly shaped hole in the jaw head 15. The length of each bar 47 is such that a portion thereof can protrude from the jaw head 15 towards the centre of the table 10.

Sliding of each bar 47 and hence the respective jaws 20, 21, in the jaw head 1 5 is facilitated by a knob 48 which is secured to the outer end 49 of the bar 47. The inner end 50 of the bar 47, is provided with a protruding pad 51 which serves to abut the workpiece and is made of a suitably resilient material. To facilitate locking of the jaws" 20. 21 when they are positioned so also abut the workpiece, each jaw 20. 21 is provided along its upper and lower surfaces with respective friction pads 52. A further loose spacer 53 separates vertically from one another the two jaws 20, 21.

When the ram 44 is actuated it presses the spacer 46, jaw 21, spacer 53 and jaw 20 against the jaw head's interior surface thereby locking the jaws 20,21.

The table 10 is provided with four jacks 54 some or all of which can be used optionally, as may be desired for supporting the workpiece from underneath e.g. when the workpiece has first been positioned on the table 10 and prior to clamping, for getting the workpiece into the correct position.

Each said jack 54 is removably locatable on the table 10 in a respective position between a respective adjacent pair of the jaw heads 1 5 so that each jack 54 extends inwardly from the outside of the table 10 towards the centre. Each jack 54 comprises a pivotal arm 55 which is square in cross-section, but it could also for example, be rectangular in cross-section, this arm 55 being pivotally connected adjacent one of its ends to actuating means 56 for the jack 54 and at its other end is connected to a mounting plate 57 disposed on the table 10.

The table 10 is provided with four recesses 58, one being disposed radially of the table 10 about midway between each adjacent pair of jaw heads 15. Each recess 58 accommodates the actuating means 56 of its respective associated jack 54, which actuating means 56, as can be more clearly seen from Figs. 6 and 7, comprises a threaded rod 59 which extends through two spaced-apart blocks 60, 61 resting in the recess 58 and through a further block 62 which is adjustable along the length of the threaded rod 59. This further block 62 has pivtoally connected thereto a pair of link rods 63, one end of each said link rod 63 being secured to a respective side of the block 62 by means of a pivot pin 64 extending through the block 62 and through each said end of each link rod 63.The other end of each link rod 63 is pivotally connected to a respective side of the pivotal arm 55 by means of another pivotal pin 65 extending through the arm 55, adjacent one end thereof, and through each said end of each said link rod 63.

Formed integrally with one end of each threaded rod 59 is a square sectioned extension 66 by which the threaded rod 59 can be rotated by a suitable tool (not shown).

As previously mentioned, the inner end of the pivotal arm 55, which end is remote from the link rods 63, is itself pivotally connected to the mounting plate 57. The mounting plate 57, like the table 10, is octagonal in shape when considered in plan and has on its underside a square or cylindrical protrusion 67 which is engageable in a correspondingly-shaped hole 68 in the centre of the table 10 so as to sit securely on said table 10. The dimensions of the mounting plate 57 are such that its peripheral edge is not within the extent of adjustment of the jaw assemblies 11, 12, 1 3, 14 towards the centre of the table 10.

Cut into the peripheral edge of the mounting plate 57 are four equispaced gaps 69. A respective reduced portion 70 on the inner end of each pivotal arm 55 engages into a respective one of three gaps 69 and is pivotally secured therein by a respective pivot pin 71 which extends through respective holes 72 in the mounting plate 57 on opposing sides of the gap 69 and through a respective hole 73 in the reduced portion 70 on the pivotal arm 55. The pivot pin 71 is prevented from working itself loose by respective grub screws 74 which are secured in respective holes, in the mounting plate's upper surface, which holes intersect with a respective one of the holes 72 in which pivot pin 72 is accommodated in the mounting plate 57.

Each pivotal arm 55 is, therefore, provided with a respective pivotal location at each of its ends. In its normal position, part of each arm 55 lies flat against the table 10. However, upon adjustment of the actuation means 56 by turning its threaded rod 59 to move the block 62 radially inwards of the table 10, the respective pivotal arm 55 is pivoted upwards so that it provides support for the workpiece from underneath. It will, of course, be usual to support the workpiece by means of the jacks 54, before clamping the workpiece with the jaws 20 to 25, the jacks 54 enabling the workpiece to be located on the table 10 into any desired clamping position.

It will be appreciated from the foregoing that when the clamping means of each jaw head 15 is actuated the jaws 20, 21 and the jaws 22 to 25 are locked in their adjusted positions in their respective jaw head 15, and cannot be moved.

However, as illustrated in Fig. 5, an alternative form of jaw may be used, with the jaw heads 15, in place of the jaws 20, 21 and 22 to 25. This alternative jaw 75 comprises a rectangular bar 76 having a longitudinally extending hole, one part of which hole has a larger diameter than the other and is threaded. A threaded rod 77 extends through the hole so that one end of a reduced portion 78 of the rod 77 can extend beyond the bar 76. When each jaw 75 is locked in position by the clamping means, further tightning of the workpiece by the jaws 75 is possible by turning knurled knob 79 at one end of the threaded rod 77.

The invention is not confined to the precise details of the foregoing example and variations may be made thereto. Thus, whilst the abovedescribed arrangement has one pair of clamping jaw heads with two jaws and another pair with four jaws, the apparatus may have any desired arrangement of multiple jaw heads. Moreover, there may, for instance, be only three jaw heads (arranged at 1200 spacing) and in some instances it might be desirable for there to be more than four jaw heads. Naturally, the manner of clamping the jaws in the jaw heads may differ from what has been described, as also may the form of the jacks, and the manner in which the latter may be swung up and down to support the workpiece from below.

Claims (17)

1. Clamp apparatus comprising a support body for receiving a workpiece, there being, on said support body, spaced-apart jaw assemblies each of which comprises at least two jaws individually extensible to enable the workpiece to be clamped.

2. Apparatus as claimed in claim 1 wherein each jaw assembly is adjustably mounted on a support body and is in the form of a respective jaw head in which the respective jaws are slidable.

3. Apparatus as claimed in claim 2 wherein there are four jaw heads on the support body, arranged in opposed pairs, with one of the opposed pairs disposed at a right angle to the other opposed pair.

4. Apparatus as claimed in claim 2 or 3 wherein each jaw head has either two jaws or four jaws.

5. Apparatus as claimed in claim 2 or 3 wherein the respective jaw heads of one opposed pair each have two jaws, and the respective jaw heads of the other opposed pair each have four jaws.

6. Apparatus as claimed in any of claims 2 to 6 wherein each jaw head comprises clamping means to enable the respective jaws to be locked in there respective adjusted positions.

7. Apparatus as claimed in claim 6 wherein the jaw head has four jaws and the clamping means is arranged at one side of the jaw head.

8. Apparatus as claimed in claim 6 wherein the jaw head has two jaws and the clamping means is arranged on said jaw head's underside.

9. Apparatus as claimed in any of claims 6 to 8 wherein the clamping means comprises a cylinder having a hollow piston and a hollow ram and a stud which extends through the cylinder and slidably mounts the piston and the ram, the stud having slidably mounted thereon a mounting block to which is secured a pair of pressure plates for pressing against the upper and lower pairs of jaws respectively.

10. Apparatus as claimed in any preceding claim wherein each jaw is individually adjustable, to clamp the workpiece further, after it has been locked into position by the clamping means.

11. Apparatus as claimed in any preceding claim wherein one or more jacks are supported on the support body, each said jack being removably located thereon so as to be disposed between a repsective adjacent pair of the jaw heads.

12. Apparatus as claimed in claim 11 wherein each jack comprises a pivotal arm which is adjustable to provide support for a workpiece from underneath.

13. Apparatus as claimed in claim 11 or 12 wherein each jack comprises actuating means comprising a threaded rod extending through a block and a pair of link rods pivotally connected to the block and to the pivotal arm, the block being adjustable along the threaded rod to enable the pivotal arm to be swung upwardly to support the workpiece.

14. Apparatus as claimed in claims 11, 12 or 13 wherein the support body may be provided with respective recesses to accommodate the actuating means of each of the jacks.

15. Apparatus as claimed in any of claims 12 to 14 wherein a removable mounting plate is engageable in a fixed location on the support body to provide pivotal connections for one end of each of the pivotal arms so that each said arm can be swung upwards, away from the support body, to enable it to support the workpiece.

16. Apparatus as claimed in any preceding claim wherein the support body is a table.

17. Clamp apparatus substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.