GB1573107A

GB1573107A - Clamps

Info

Publication number: GB1573107A
Application number: GB1411176A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1976-04-07
Filing date: 1976-04-07
Publication date: 1980-08-13
Also published as: JPS52123000A; DE7710841U1; AU2392477A; FR2347156A1; DE2715267A1

Description

(54) IMPROVEMENTS IN OR RELATING TO CLAMPS (71) I, GERALD ERNEST SADLER, a British Subject, of Raydons House, Dagenham, Essex, do hereby declare this invention, for which I pray that a patent may be granted to me, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to clamps. Although the invention is concerned with ordinary clamps, which are designed to hold or grip objects between their jaws, the invention is also concerned with devices in which the jaws or movable members have outwardly directed operative faces and are designed to press outwardly relative to one another, for example.

against the inner surface of a cylinder. Thus, the term "clamp" when used herein should be construed to include also such outwards pressing devices.

According to the invention there is provided a clamp comprising a pair of clamp portions each having an operative face for contact with a workpiece, the clamp portions being arranged for relative sliding movement such as to alter the spacing of the operative faces but with substantially no alteration of their relative orientation, spring means arranged to urge the clamp portions such that, in use, the operative faces are urged against a workpiece, and abutments associated with each of the clamp portions and adapted to be cooperatively engageable by a separate tool by which the clamp portions can be moved relative to one another in opposition to the loading of the spring means, the clamp portions having respective elongate parts which extend transversely outwards from the line of action of the spring means and constitute jaw members for the clamp, and the operative faces being flat, mutually parallel surfaces at the outer extremities of the jaw members and defined by respective shallow depressed regions in the jaw members extending inwards from said flat surfaces. Such a clamp has the advantage that the operative faces retain their relative orientation, as in a screw-operated clamp, and the further advantages that actuation of the spring means for applying the clamp to a workpiece can be performed rapidly, whereas operation of a screw-operated clamp can be quite lengthy especially if the size of the workpiece is substantially different from the existing spacing of the operative faces of the screw-operated clamp.Furthermore, since the spring means can be actuated by means of a single actuation movement, the clamp can readily be applied to a workpiece by the use of only one hand, whereas hand operation of a screw-operated clamp cannot be readily achieved unless the clamp is supported, and frequently this requires both of an operator's hands.

The clamp may be arranged to grip the outside of a workpiece and in this case the spring means will be arranged to urge the clamp portions together. On the other hand, the clamp portions maybe arranged for internal use and the spring means will be arranged to urge the clamp portions apart.

Preferably, for enabling the relative sliding movement, one of the clamp portions has an elongate laterally extending portion, conveniently in the form of a shaft, which passes through a passage in the other of the clamp portions. It will be appreciated that the less clearance there is between the passage and the elongate portion in it, the better will the relative orientation of the operative faces be maintained.

Preferably, the spring means is in the form of a helical compression spring disposed around the elongate portion.

For an externally operating clamp, the spring means will be arranged to act on the side of the other clamp portion remote from the one clamp portion, and the elongate portion will have a head, against which the spring can act. In the case of an internally operating clamp, the spring means will be disposed between the clamp portions, and the head will be required to retain the other clamp portion captive on the elongate portion.

If required, the spring means may be of other forms, for example, a leaf spring preferably having a plurality of folds, a disc spring or a helical spring arranged to operate under tension instead of under compression, and be suitably disposed depending on its manner of operation.

The spring means may be arranged so as effectively to provide different spring constants in different portions of its range of compression, or extension, and as an example, such a spring means may comprise a helical spring, part of which is disposed inside or outside andther helical spring.

When compressing a spring acting between the other clamp portion and the head of the elongate portion, the head can act as one of said abutments, and another abutment will be provided on the other clamp portion.

Preferably, for enabling the relative orientation of the operative faces to be maintained substantially, the clamp portions have respective complementary guide means, which may be in the form of a tongue formed on one of the clamp portions and a complementary groove in the other of the clamp portions. The walls of the groove may be extended towards the tongue by means of similar tongues formed on the other of the clamp portions, in this manner the orientation can be so maintained over a given relative movement while permitting a reduction in the size of the tongue on the one of the clamp portions compared with the size required when the other of the clamp portions has no similar tongues for extending its groove walls.

It will be understood that the term "workpiece" as used herein means one or more articles, as appropriate. Furthermore, the shape of the operative faces will be selected in accordance with the use of the clamp, and may be, for example, flat, curved or V-shaped.

A hand tool for use with the clamp as described above, may comprise two pivotally connected levers, the jaw portion of one of the levers being open-ended for receiving a part of one of the clamp portions of the clamp adjacent an abutment thereof, and the jaw portion of the other of the levers being either similarly open-ended for receiving a similar part of the other of the clamp portions, or formed with a recess receiving an abutment in the form of a head, or formed as a combination of these two shapes. The jaw portion of the one lever can similarly be of such a combination of shapes thus simplifying manufacture of the hand tool.

Conveniently the spring means of the clamp is actuated upon squeezing together the handle portions of the hand tool. Thus where a compression of the spring means is required, the levers are connected in a scissor-like manner, but where a tension spring means is used, the levers will be arranged such that the jaw portions move apart when the handle portions move together. Tension spring means may be used in a clamp for use with a relatively large diameter workpiece (i.e. one larger than the opening obtainable with a clamp whose operative faces are substantially together in the nonworking condition); in such a clamp there is a relatively large initial opening of the operative faces, and the abutments may take the form of recesses or heads, as required and the corre- sponding hand tool will have appropriate jaw portions.

The parts of the clamp at which the abutments are provided are preferably cylindrical in shape thereby enabling the orientation between the clamp and the hand tool to be variable about the axis of these cylindrical parts between limiting positions determined by the shape of the hand tool.

An embodiment of a clamp in accordance with the present invention and of a tool for applying the clamps will now be described by way of example with reference to the accompanying drawing in which: Figure 1 is a side elevation of a clamp; Figure 2 is a partially sectioned view along the lines A-A of part of the clamp of Figure 1; Figure 3 is a view along the lines B-B of part of the clamp of Figure 1; and Figures 4 and 5 are views of the operative parts of a tool for applying the clamp.

In Figures 1 to 3 a clamp comprises a clamp portion 10, and a clamp portion 11 slidable along an elongate laterally extending portion of clamp portion 10 in the form of a shaft 12 which passes through a bore 13 in clamp portion 11. The clamp portions 10, 11 have respective complementary elongate parts 10' and 11 which constitute a pair of jaw members for the clamp. One end of the shaft 12 is formed as a domed head 14 and the other end of the shaft 12 is threaded and engages in a correspondingly threaded hole (not shown) in the remainder of clamp portion 10. The axis of the threaded hole is arranged substantially perpendicular to the plane of an internal gripping face 15 at the free end of jaw member 10 and the axis of bore 13 is arranged substantially perpendicular to an internal gripping face 16 at the free end of jaw member 11 so that as clamp portion 11 slides on shaft 12 the gripping faces 15 and 16 remain substantially parallel to and facing each other.

Clamp portion 11 has a laterally extending portion in the form of a cylindrical body 17 through which the bore 13 passes coaxially.

Body 17 has a reduced diameter neck 18 adjacent its free end, and the bore 13 has an enlarged diameter region at the free end of body 17 so as to form a cylindrical recess 19 in the body 17. The diameter of body 17 is slightly larger than that of domed head 14.

A compression spring 20 is disposed around shaft 12 and acts between the head 14 and the bottom of the recess 19 to urge the clamp portions together.

In order to keep the jaw members aligned, the dimensions of the shaft 12 and bore 13 are selected for a clearance fit, and the clamp portions 10, 11 are formed at their ends opposite the gripping faces with respective guide members 21 and 21', and 22 to prevent relative rotation about the axis of shaft 12. The guide members 21,21' on clamp portion 10 are parallel and spaced apart; they extend parallel to shaft 12 a distance a from the plane of gripping face 15 and are arranged on each side of complementary guide member 22 which extends parallel to bore 13 a distance b.from the plane of gripping face 16. Thus an opening of up to a + b can be obtained (depending on the selection of spring 20 and the length of shaft 12) with the guide members 21, 21' and 22 co-operating to prevent the abovementioned relative rotation.

To define the areas of the gripping faces 15 and 16, each clamp portion has a shallow depressed region 23 which extends from the gripping face of its jaw member to a small wall 24 (Figure 2) at the other end of the clamp portion. These walls are of the same height above their respective regions 23 as are the gripping faces, and abut each other in the closed condition of the clamp, and thus any tendency for the gripping faces to splay apart, pivoting about a transverse axis at their inner edges, is avoided.

The clamp portion 10, and clamp portion 11 (except for cylindrical body 17) are die-cast from a leadlzinc alloy. Alternatively, if required, they can be made from bronze or steel or any other suitable material.

The cylindrical body 17 is formed of mild steel and is attached to the remainder of clamp portion 11 by means of a pressing operation.

Again, other materials can be employed for body 17, if required, for example, bronze.

To use the clamp, body 17 and head 14 are urged towards each other, thus opening a gap between the gripping faces and compressing the spring 20. The limit of the opening is determined by the minimum length to which the spring 20 can be compressed, i.e. when adjacent turns of the spring are in contact with each other. The article or articles to be clamped are then inserted between faces 15 and 16 and the force compressing spring 20 is removed thus allowing clamping of the article or articles under the action of spring 20. The clamp can be removed from the article or articles by simply pulling so that the faces slide off. However, where such action could damage an article, it would be preferably to open the clamp in the same manner as when it was applied, to release the clamping force.

In the abovedescribed clamp, the spring 20 has an initial compression when the faces 15 and 16 are in contact. If required, a shorter spring, or a longer shaft, or a deeper recess, or any combination of these, can be used so that there is a certain amount of free play when the clamp is not in use.

The clamping force will depend on the spring constant and on the amount of compression of the spring at the required opening of faces 15 and 16, and thus the clamp can be made to meet customer requirement by suitable selection of these parameters.

The overall length of the clamp portions 10, 11, including the jaw members 10', 11' is approximately 4 cms, and the gripping faces are in the shape of a trapezium having a length of approximately 7mm and tapering from a width of 9mm to a width of 7mm at the extreme end of the jaw member. If required the overall length can be longer or shorter.

It will be appreciated that the above described clamp provides the advantage that the gripping faces always remain parallel to each other; also that such clamps are compact and by suitable selection of clamping force can be an acceptable alternative to the conventional G-clamp.

A tool for use in compressing the spring of the above-described clamp comprises a pair of levers each having a handle portion and a respective jaw portion 25, 26, and being pivotably connected together in the manner of scissors.

Figure 4 is a view of the jaw portion 25 particularly adapted to cooperate with the neck 18 of the clamp. It has an open end 27 of slightly greater width than the diameter of neck 18. (In certain cases, the width of the open end can be selected for an interference fit so that the clamp will not readily fall from the tool.) The open end leads into a semicylindrical blind end 28, and the inner face of jaw portion 25 is recessed at 29 to accommodate the free end of body 17.

Figure 5 is a view of the other jaw portion 26 which is particularly adapted to cooperate with the head 14 of the clamp. It has a cylindrical cup part 30 which extends inwardly and perpendicularly to a general plane of the end of the jaw portion. Cup part 30 has a cylindrical recess 31 the bottom of which has a V-shaped cross-section. If required, the cross-sectional configuration of the bottom of recess 31 can be arcuate or any other suitable shape depending on the shape of head 14.

Whereas head 14 in the above described clamp is of slightly smaller diameter than that of body 17, alternatively it may be of the same diameter as body 17. In this manner, a hand tool can be made having identical jaw portions 25. The recess 29 could be formed at its ends with a latch formation to assist in keeping head 14 captive but permit easy fitting to body 17.

If required, head 14 may be made flat instead of domed, and there can be provided a screwslot or similar arrangement to facilitate the screw connection of shaft 12 to clamp portion 10.

In a modification of the above described clamp in which the gripping faces are arranged externally of the jaw members, as opposed to internally as in Figure 1, the compression spring will be disposed between the clamp portions and the hand tool will be required to urge the clamp portions together. The force applied by the hand tool can be conveniently between that abutment, formed by neck 18, further from the free end of body 17, and the outside of clamp portion 10 remote from shaft 12. It may be convenient to provide a projection at this part, similar in shape to head 14, in order to facilitate the use of a hand tool common to the two type types of clamp.

Whereas in the above described embodiment the relative orientation is maintained by means of the guide members 21, 21' and 22, it will be appreciated that an alternative technique is to use a shaft having a non-circular cross-section, and a correspondingly shaped bore.

It will be appreciated that the present invention is directed to the spring loaded sliding action in clamps and is not to be limited to a particular form of clamp portion. Accordingly, a clamp may have two or more pairs of elongate jaw members angularly spaced about the shaft axis. If desired, a plurality of jaw members can be effectively provided by a clamp portion generally in the form of a body of rotation about the shaft of, say, the clamp portion in Figure 1. If further desired a clamp could comprise two such bodies of rotation.

WHAT WE CLAIM IS: 1. A clamp as hereinbefore defined comprising a pair of clamp portions each having an operative face for contact with a workpiece, the clamp portions being arranged for relative sliding movement such as to alter the spacing of the operative faces but with substantially no alteration of their relative orientation, spring means arranged to urge the clamp portions such that, in use, the operative faces are urged against a workpiece, and abutments associated with each of the clamp portions and adapted to be cooperatively engageable by a separate tool by which the clamp portions can be moved relative to one another in opposition to the loading of the spring means, the clamp portions having respective elongate parts which extend transversely outwards from the line of action of the spring means and constitute jaw members for the clamp, and the operative faces being flat, mutually parallel surfaces at the outer extremities of the jaw members and defined by respective shallow depressed regions in the jaw members extending inwards from said flat surfaces.

2. A clamp as claimed in claim 1 wherein, for enabling the relative orientation of the operative faces to be maintained substantially, the clamp portions have respective complemen tary guide means.

3. A clamp as claimed in claim 2 wherein said guide means is in the form of a tongue formed on one of the clamp portions and a complementary groove in the other of the clamp portions.

4. A clamp as claimed in claim 3 wherein the walls of the groove extend towards the tongue by means of similar tongues formed on the other of the clamp portions.

5. A clamp as claimed in any one of claims 1 to 4 wherein, for enabling the relative sliding movement, one of the clamp portions has an elongate laterally extending portion which passes through a passage in the other of the clamp portions.

6. A clamp as claimed in claim 5 wherein the spring means is in the form of a helical com pression spring disposed around said elongate portion.

7. A clamp as claimed in either claim 5 or claim 6 having internal operative faces for con tacting the exterior of the workpiece, and wherein the spring means is arranged to act on the side of the other clamp portion remote from said one clamp portion, and on a head on said elongate portion.

8. A clamp as claimed in either claim 5 or claim 6 having external operative faces for con tacting the workpiece interiorly, and wherein the spring means is disposed between the clamp portions and there is provided a head on said elongate portion for retaining said other clamp portion captive.

9. A clamp as claimed in claim 7 wherein the head of the elongate portion constitutes one of said abutments, another abutment being provided on said other clamp portion.

10. A clamp substantially as hereinbefore de scribed with reference to and as shown in Figures 1 to 3 of the accompanying drawings.

11. A clamp as claimed in any preceding claim in combination with a hand tool for cooperative engagement with said abutments, the hand tool comprising two pivotally connected levers, the jaw portion of one of the levers being open-ended for receiving a part of one of the clamp portions of the clamp adjacent an abutment thereof, and the jaw portion of the other of the levers being either similarly open-ended for receiving a similar part of the other of the jaw members, or formed with a recess for receiving an abutment in the form of a head, or formed as a combination of these two shapes.

12. A clamp and hand tool combination as claimed in claim 11 wherein the jaw portion of said other lever is open-ended and of substantially the same shape as the jaw portion of said one lever, both jaw portions being formed with or without a said recess for receiving an abutment in the form of a head.

13. A clamp and hand tool combination as claimed in claim 11 wherein the hand tool is substantially as hereinbefore described with

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. of domed, and there can be provided a screwslot or similar arrangement to facilitate the screw connection of shaft 12 to clamp portion 10. In a modification of the above described clamp in which the gripping faces are arranged externally of the jaw members, as opposed to internally as in Figure 1, the compression spring will be disposed between the clamp portions and the hand tool will be required to urge the clamp portions together. The force applied by the hand tool can be conveniently between that abutment, formed by neck 18, further from the free end of body 17, and the outside of clamp portion 10 remote from shaft 12. It may be convenient to provide a projection at this part, similar in shape to head 14, in order to facilitate the use of a hand tool common to the two type types of clamp. Whereas in the above described embodiment the relative orientation is maintained by means of the guide members 21, 21' and 22, it will be appreciated that an alternative technique is to use a shaft having a non-circular cross-section, and a correspondingly shaped bore. It will be appreciated that the present invention is directed to the spring loaded sliding action in clamps and is not to be limited to a particular form of clamp portion. Accordingly, a clamp may have two or more pairs of elongate jaw members angularly spaced about the shaft axis. If desired, a plurality of jaw members can be effectively provided by a clamp portion generally in the form of a body of rotation about the shaft of, say, the clamp portion in Figure 1. If further desired a clamp could comprise two such bodies of rotation. WHAT WE CLAIM IS:

1. A clamp as hereinbefore defined comprising a pair of clamp portions each having an operative face for contact with a workpiece, the clamp portions being arranged for relative sliding movement such as to alter the spacing of the operative faces but with substantially no alteration of their relative orientation, spring means arranged to urge the clamp portions such that, in use, the operative faces are urged against a workpiece, and abutments associated with each of the clamp portions and adapted to be cooperatively engageable by a separate tool by which the clamp portions can be moved relative to one another in opposition to the loading of the spring means, the clamp portions having respective elongate parts which extend transversely outwards from the line of action of the spring means and constitute jaw members for the clamp, and the operative faces being flat, mutually parallel surfaces at the outer extremities of the jaw members and defined by respective shallow depressed regions in the jaw members extending inwards from said flat surfaces.

reference to Figures 4 and 5 of the accompanying drawings.