GB2177647A - Adjustable clamp - Google Patents

Abstract

In a clamp in which fine adjustment of one jaw 10 is effected by a screw 17 which is rotated to cause a lever 11 carrying the jaw to pivot on a support beam 1, the screw 17 engages a threaded adaptor 16 which is mounted for swiveling movement in a recess 31 in the lever such that the screw remains normal to the beam on pivotal movement of the lever. The clamp may be used with the jaws 5 and 10 directed towards each other or directed in opposite directions. <IMAGE>

Description

SPECIFICATION Mechanical adjustment means and tools comprising mechanical adjustment means This invention relates to mechanical adjustment means and to tools including mechanical adjustment means, the means comprising an anchor component, a movable component and a screw arrangement for moving the movable component relative to the anchor component.

In particular, although not exclusively, the present invention relates to mechanical adjustment means for clamps or jacks.

Known clamps comprise an elongate beam or anchor component and two jaw components, at least one of which jaw components is movably mounted relatively to the beam in order to adjust the distance between the jaw components.

Such a clamp typically features a relatively coarse mechanical adjustment for enabling quick adjustment of the distance between the jaws to an approximate desired setting and a relatively fine mechanical adjustment enabling a final clamped setting of the jaws to be achieved. The relatively coarse adjustment usually comprises a step by step incremental adjustment and the relatively fine adjustment usually comprises mechanical screw means. In some clamps the coarse adjustment is set by inserting a pin through holes in an arm on which the jaw is carried and through the beam, but in others a similar result is obtained by providing notches on the beam and arranging that a lug or pin on the arm engages in a selected notch.One example of such a prior known clamp is shown in British Patent Specification number 863 441, the movable jaw being formed by one arm of a bellcrank lever having a fulcrum lug engageable in a notch, the other arm of the bell crank lever is slidably mounted on the beam and is provided with a fine screw adjustment arranged to act on the beam to urge the movable jaw into clamping engagement with a work member causing the lever to turn angularly about its fulcrum. The screw adjustment may be in the form of a rotatable screw engaged in a screw threaded hole or boss provided towards the end of said other arm remote from the fulcrum, the screw being arranged to bear on an outer surface of the beam so that by rotating the screw such that it moves towards the beam the said other arm of the bell crank lever is moved outwards relative to the beam.Thereby, the jaw, constituted by the other arm, is urged towards its clamped mode.

One disadvantage of such prior known clamps is that, in use, as the bell crank lever is pivoted about the fulcrum the angular relationship between the screw of the fine adjustment and the beam is varied and becomes such that the screw is subjected to a bending force. Thus, in use, the screw frequently is bent.

One object of the present invention is to provide mechanical adjustment means which tends to overcome or reduce the above mentioned disadvantage.

According to the present invention mechanical adjustment means comprises an anchor member or beam, a component of generally bell crank lever form mounted on the anchor member or beam for pivotal movement about a fulcrum, one arm of the bell crank lever component being provided with a work engageable portion and the other arm of the lever component being provided with a recess, and a screw adjustment comprising a support adaptor retained within the recess but capable of swivelling within the recess, the support adaptor being provided with a threaded bore engaged by a screw member extending transverse to said other arm to engage a formation provided on the anchor member or beam such that, in operation, rotation of the screw member urges the bell crank lever component to pivot about the fulcrum and the work engageable portion is urged towards a work engaged mode, throughout pivoting the support adaptor swivels within the recess such that reaction forces acting between the screw member and the formation act substantially along the screw member.

Preferably, the end of the screw member in engagement with the formation is part cylindrical or part spherical.

Advantageously, the formation defines a part cylindrical or part spherical recess for engagement by the screw member.

Preferably, the fulcrum is adjacent to the intersection of the two arms of the bell crank lever component.

Preferably, the recess provided in said other arm has at least a portion defining a part cylindrical or part spherical surface.

Advantageously, the support adaptor defines a part cylindrical or part spherical surface for co-operation with the part cylindrical or part spherical surface defined by the recess enabling the support adaptor to swivel within the recess.

Preferably, the support adaptor swivels such that the screw member remains substantially perpendicular to the anchor member or beam.

Preferably, the work engageable portion of said one arm is constituted by an engagement jaw pivotally mounted on the arm.

The present invention also provides within its scope a clamp comprising mechanical adjustment means as defined above.

Preferably, the clamp comprises a second work engageable jaw provided on a second arm component mounted on the anchor member or beam, the two work engageable jaws being directed towards one another.

Preferably, the second arm is slidable along the anchor member or beam between a series of operational positions.

The present invention also provides within its scope a jack comprising mechanical adjustment means as defined above.

Preferably, the jack comprises a second work engageable portion provided on a second arm mounted on the anchor member or beam, the two work engaging portions being directed in opposed directions.

The present invention also provides a multi pur pose tool comprising an anchor member or beam, and two arm components capable of being fixedly mounted on the beam but also capable of being moved along the beam between fixed mountings, the arm components having work engageable portions, the arm components being adjustable or resettable in order to facilitate the tool functioning as a clamp with the work engageable portion directed towards each other as a jack with the work engageable portions directed in opposed directions.

Preferably, the tool comprises mechanical adjustment means as defined above.

By way of example, three embodiments of the present invention will be described with reference to the accompanying drawings, in which: Figure 1 is a side elevation of a clamp constructed in accordance with one embodiment of the present invention; Figure 2 is a part sectional side elevation of the clamp of Figure 1; Figure 3 is a plan of the clamp of Figure 1; Figure 4 is a part sectional side elevation of a clamp constructed in accordance with a second embodiment of the present invention, the clamp being of a bench holdfast form; Figure 5 is an inverted plan of a detail of the clamp of Figure 4 showing an annular boss from beneath the bench; and Figure 6 is a side elevation of a clamp constructed in accordance with a third embodiment of the present invention, the clamp being adapted to provide a stable bench mounted workholding fixture.

Referring to the drawings, Figure 1, 2, and 3, show a first embodiment of clamp comprising an anchor member or beam 1 of generally rectangular girder section which is rigidly made of steel or malleable iron. The beam is formed on its back edge or face with a series of rack teeth 2 and two recessed formations 3 and 4 (see particularly Figure 2). On its front edge or face the beam is formed with two recesses 14 and 20.

The clamp of Figures 1, 2, and 3, also comprises two arms 6 and 11 provided with work engageable jaws 5 and 10, respectively. As seen in Figures 1 and 2 the two jaws are directed towards one another.

The jaw 5 is fixedly mounted on the arm 6 which has a hollow box-like rear portion 7 defining a passage for the beam 1. The box-like portion is formed internally with a number of rack teeth 8 which engage the rack teeth 2 provided along the beam. Engagement of the two sets of rack teeth 2, 8 is maintained to the arm within the box-like portion. As seen in Figure 2 the face of the box-like portion remote from the rack teeth 8 tapers outwardly enabling the arm to be tilted in an anticlockwise direction as seen in Figure 2 to disengage the rack teeth 8 from the rack teeth 2 enabling the arm 6 to be slid along the beam to a new desired setting. Tilting of the arm is done against the action of the spring 9 which once the arm is released in its new desired setting urges the rack teeth 2 and 8 once more into engagement.The facility of being able to move the arm 6 along the series of rack teeth along the beam provides the relatively coarse adjustment feature of the clamp.

The arm 6 including the box-like portion and the jaw 5 may be cast integrally in malleable iron.

The other arm 11 is constituted by one arm of a generally bell crank lever component 11, 30 which may be cast integrally in malleable iron. The other arm 11 of the lever component extends in an oblique direction downwards and away from said one arm. The component is provided with a hollow box-like rear portion 12 defining a passage for the beam 1 and formed internally with a lug 13 which locates in a recess 14 provided on the front edge or face of the beam. The lug has a part cylindrical or part spherical surface which co-operates with a part cylindrical or part spherical surface defined by the recess enabling the lug 13 to form a fulcrum for the bell crank lever component.As seen in the drawings the fulcrum is adjacent to the intersection of the two arms 11 and 30 of the lever component which is pivoted about the fulcrum under the action of a screw adjustment 15, 16 and 17 as will now be explained. Adjacent to the end of the arm 30 remote from the fulcrum is an integral boss 15 (see particularly Figure 2) which is provided with a through passage or recess 31. The recess is tapered outwardly at each end in the form of bell mouths and has an inner portion defining a part cylindrical surface 32. In modified recesses the inner portion defines a part spherical surface.The inner portion of the recess houses a generally cylindrical support adaptor or bush 16 which is provided with a threaded through cross bore 16 which is provided with a threaded through cross bore 33 and has an outer boundary defining a part cylindrical surface corresponding to the aforementioned part cylindrical surface defined by the inner portion of the recess. The arrangement ensures the support adaptor or bush is retained in the inner portion of the recess but its free to swivel about its longitudinal axis which is transverse to the axis of the recess 31. In the modified recesses where a part spherical surface is defined the support adaptor or bush will define a corresponding part spherical surface.

The threaded cross bore 33 receives an elongate screw member 17 having a handle on one end for rotating the screw member within the bore 33 and a nose at the opposite end which defines a part cylindrical or part spherical surface and which engages in one of the two previously mentioned recessed formations 3. The recessed formation 3 define a part cylindrical or part spherical surface corresponding to that defined by the nose of the screw member. As indicated in Figure 2 of the drawings the support adaptor 16 has swivel within the recess 31 such that the screw member 17 is substantially perpendicular or normal to the longitudinal direction of the beam and transverse to the arm of the lever component.

A resilient blade spring 18 is fixedly secured to the arm 30 of the lever component, the spring extending upwards and inwards so as to push against the rear edge or face of the beam and thereby maintain engagement of the fulcrum lug 13 in the recess 14 provided on the beam. The action of the spring 18 also urges the upper arm 11 in a direction away from a clamped mode, ie away from the opposed jaw 5.

The clearance between the internal features of the box-like section 12 and the beam 1 is such that by overcoming the action of the spring 18, and providing the screw member 17 is slackened off, the arm cam be moved upwards so that the fulcrum lug can ride over the beam into another operational mode as will be explained later in the specification.

Two removable bolts 19 and 34 are provided at the opposite ends of the beam 1 to prevent inadvertent removal of the arm components 6, and 11, 30 from the beam.

In use, a work object (not shown) is clamped in inserted between the two jaws 5 and 10. The arm 6 carrying jaw 5 is tilted to disengage the rack teeth 2 and 8 permitting coarse adjustment of the jaw opening to approximately suit the work object.

Once the rack teeth are disengaged the arm 6 is slid along the beam up to the work object. The arm 6 then released permitting the spring 9 to re-engage the rack teeth to retain the arm in its new set position.

The clamp then is finely adjusted into its clamped mode by turning the screw member 17 within the support adaptor 16. By rotating the screw member 17 in the correct direction the bell crank lever component 11, 30 is pivoted about the fulcrum and the work engageable portion or jaw 10 is urged towards its work engaged mode in which the work object is firmly clamped between the jaws. Throughout the fine adjustment ie throughout the pivoting of the lever component, the support adaptor swivels within the recess to compensate for pivoting of the lever component such that re-action or thrust forces between the screw member 17 and the recessed formation 3 act substantially along the screw member. Thus, there is little or no tendancy for the screw member to be bent in the clamping operation.Throughout the fine adjustment the support adaptor or bush 16 swivels within the recess such that the screw member substantially remains perpendicular as normal to the beam.

The tool shown in Figure 1 and 2 can be converted from a clamp to a jack by removing the two retaining screws 19 and 34 by removing the two arm components 6 and 11, 30 from the beam, the two arm components being turned through 180 and re-mounted on the beam with the work engageable jaws 10 and 5 directed in opposite directions. The arm components are retained in desired set positions in similar manner to that previously described. The rack teeth 8 of the arm component 6 are engaged in the rack teeth 2 along the beam 1 and the fulcrum lug 3 is engaged in a second recess 20 which is similar to the previously described recess 14. Also the screw member 17 is engaged in a recessed formation 4 of similar form to the previously discussed formation 3.

With the arm components fixedly mounted on the beam the work engageable portions 5 and 10 of the components are inserted between two work objects to be urged apart. By similar coarse the fine adjustment operations to those previously described with reference to the clamp the jaws are urged apart thereby enabling the tool to constitute a jack.

The work engageable portions or jaws of the tool whether functioning as a clamp or as a jack may be flat, serrated or grooved to facilitate engaging circular work objects.

The shape of the recessed formations 3 and 4 is such that the nose end of the adjustment screw member is prevented from moving towards or away from the fulcrum or from moving sideways.

Thus, it is ensured that the thrust or reaction forces are directed substantially down the central longitudinal axis of the screw member thereby avoiding bending of the screw member.

Figure 4 and 5 illustrate a second embodiment of clamp in which the clamp is of a bench hold fast form.

The beam 1 and the bell crank lever component 11, 30 substantially are identical to the equivalent items previously described with reference to Figure 1, 2 and 3 and the same reference numbers have been used for similar parts. Moreover, the description of these items is not repeated.

In the embodiment illustrated in Figures 4 and 5 one arm component of the first described embodiment is replaced by an annular boss 21 fixedly mounted by studs 36 on to a work bench 22. The work bench has a circular hole 23 co-axial with the annular boss.

The annular boss is formed on its inner cylindrical face with grooves 37 of such form that when the beam is inserted into the hole 23 and through the boss the rack teeth 2 along the beam fixedly engage in the grooves 37 which thereby define teeth similar in operation to the teeth 8 of the first described embodiment.

in use, with a work object (not shown) requiring to be clamped to the work bench, the beam is held substantially vertical enabling it to be slid through the annular boss until the approximate desired setting is reached. The beam then is released in an inclined position as shown in Figure 4 such that the rack teeth 2 on the beam fixedly engage the grooves 37. Once the coarse adjustment is completed the screw member 17 is rotated in identical manner to that described earlier with reference to the first embodiment until the work object is clamped. As in the previously described embodiment the reaction or thrust forces are transmitted substantially along the screw member. Consequently, there is little or no tendency for the screw member to be bent by the reaction or thrust forces.

The geometry of the second embodiment is such that as the fine adjustment screw member 17 is tightened, the rack teeth on the beam are urged into tighter engagement in the grooves formed in the boss. The annular form of the boss provides for 360 of rotational positioning of the holdfast tool.

In modified constructions of the second embodiment the boss need not be of annular form but may have one or a series of rectangular slots passing through it similar in form to the internal shape of box member 7 of the first described embodiment. As with the first described embodiment the bell crank lever component 11, 30 may be turned through 180 such that the work engageable portion 10 is directed away from the work bench.

Thus, the second described embodiment of tool may function alternatively as a jack as well as a clamp.

Figure 6 illustrates a third embodiment of clamp adapted to provide a stable bench mounted workholding fixture.

The beam 1 and the bell crank lever component 11, 30 substantially are identical to the equivalent items previously described with reference to Figures 1, 2 and 3 the same reference numbers have been used for similar parts. Moreover, the description of these items is not repeated.

In the third described embodiment one arm component 40 is mounted on the beam 1 in similar manner to the arm 6 of the first described embodiment. The arm component 40 is provided with a work engageable portion constituted by an abutment pad 41 mounted on an adjustable screw device 42.

The beam 1 is rigidly supported over the work bench 22 by two pillars 24 and 43, the pillar 24 being a slide or interference fit in a hole provided in the work bench. The pillar 43 is mounted to the work bench by a slide or interference fit in the hole 23 co-axial with the annular bush 21. The pillars are bolted to the beam by bolts 38 (only one of which is shown).

Claims (15)

1. Mechanical adjustment means comprising an anchor member or beam, a component of generally bell crank lever form mounted on the anchor member or beam for pivotal movement about a fulcrum, one arm of the bell crank lever component being provided with a work engageable portion and the other arm of the lever component being provided with a recess, and a screw adjustment comprising a support adaptor retained within the recess but capable of swivelling within the recess, the support adaptor being provided with a threaded bore engaged by a screw member extending transverse to said other arm to engage a formation provided on the anchor member or beam such that, in operation, rotation of the screw member urges the bell crank lever component to pivot about the fulcrum and the work engageable portion is urged towards a work engaged mode, throughout pivoting the support adaptor swivels within the recess such that reaction forces acting between the screw member and the formation act substantially along the screw member.

2. Means as claimed in claim 1, in which the end of the screw member in engagement with the formation is part cylindrical or part spherical.

3. Means as claimed in claim 1 or 2, in which the formation defines a part cylindrical or part spherical recess for engagement by the screw member.

4. Means as claimed in claim 1, 2 or 3, in which the fulcrum is adjacent to the intersection of the two arms of the bell crank lever component.

5. Means as claimed in any one of the preceding claims, in which the recess provided in said other arm has at least a portion defining a part cylindrical or part spherical surface.

6. Means as claimed in claim 5, in which the support adaptor defines a part cylindrical or part spherical surface for co-operation with the part cylindrical or part spherical surface defined by the recess enabling the support adaptor to swivel within the recess.

7. Means as claimed in claim 6, in which the support adaptor swivels such that the screw member remains substantially perpendicular to the anchor member or beam.

8. Means as claimed in any one of the preceding claims, in which the work engageable portion of said one arm is constituted by an engagement jaw pivotally mounted on the arm.

9. Mechanical adjustment means substantially as described herein and substantially as shown in Figures 1, 2, and 3 and in Figures 4 and 5, or in Figure 6 of the accompanying drawings.

10. An adjustable tool comprising mechanical adjustment means as claimed in any one of the preceding claims.

11. A clamp comprising mechanical adjustment means as claimed in any one of the preceding claims 1 to 9, and having a second work engageable jaw on a second arm component mounted on the anchor member or beam, the two work engageable jaws being directed towards one another.

12. Ajack comprising mechanical adjustment means as claimed in any one of the preceding claims 1 to 9, and having a second work engageable portion provided on a second arm component mounted on the anchor member or beam, the two work engageable portions being directed in opposite directions.

13. A multi purpose tool comprising an anchor member or beam, and two arm components capable of being fixedly mounted on the beam but also capable of being moved along the beam between fixed mountings, the arm components having work engageable portions, the arm components being adjustable or re-settable in order to facilitate the tool functioning as a clamp with the work engageable portion directed towards each other as a jack with the work engageable portions directed in opposed directions.

14. A tool as claimed in claim 13, comprising mechanical adjustment means as claimed in any one of the preceding claims 1 to 9.

15. Atool substantially as described herein and substantially as shown in Figures 1, 2 and 3 or in Figures 4 and 5 or in Figure 6 of the accompanying drawings.