GB2055416A - Band clamp - Google Patents

Abstract

A clamp comprises a band, opposite end portions (11, 12) of which are folded back over adjacent portions of the band. For tightening the band, there is provided a screw (18) and nut (20). The screw extends through housings (22, 23), each of which extends through an aperture in an associated one of the end portions (11, 12) and has laterally outwardly directed flanges (25) trapped between the end portion and the adjacent portion of the band. Near to its free end, each end portion of the band is secured by welding to the underlying flanges of the housing and to the adjacent portion of the band. <IMAGE>

Description

SPECIFICATION Clamp This invention relates to a clamp of the kind comprising a band which, in use, extends around a body or an assembly of bodies to be clamped and a screw and nut mechanism for tightening the band.

A variety of clamps of the kind referred to are available. Some of these are of simple construction but these simple clamps are not capable of establishing a high clamping force. In order that relatively high tensions can be established in the band, complex arrangements have been devised. It is an object of the present invention to provide a relatively simple construction of clamp which can be used to establish a high clamping force.

According to the invention, there is provided a clamp comprising a ban which, in use, extends around a body or an assembly of bodies to be clamped and a screw and nut mechanism for tightening the band, wherein opposite end portions of the band are turned back over respective adjacent portions of the band, are secured to said adjacent portions of the band and are formed with respective apertures and wherein there is associated with each end portion a respective housing for receiving the screw of said screw and nut mechanism, a first part of the housing being trapped between the end portion and said adjacent portion of the band and a second part of the housing protruding through the aperture in the end portion to receive the screw.

The clamp may comprise, in addition to the screw and nut mechanism, three components only, namely the band and two housings. A common form of screw and nut may be used. For example, the screw may have an hexagonal or round head and a cylindrical shank with an end portion of the shank remote from the head having a screw thread. In addition to the nut, the shank may carry one or more washers.

In the preferred construction, the length of each end portion of the band exceeds the length of the second part of the associated housing and the end portion is united by fusion with the adjacent portion of the band at a position spaced circumferentially of the band from the second part of the housing. By the length of the housing, we mean that dimension which extends circumferentially of the band and subsequent references herein to lateral directions are to be construed accordingly.

The first part of the housing may be united by fusion with the band, preferably at said position spaced circumferentially of the band from the second part of the housing.

The first part of the housing preferably comprises pair of flanges which extend in opposite lateral directions from the second part of the housing.

The second part of the housing may overlie a surface of each end portion of the band adjacent to one end of the aperture therein. This arrangement ensures that, on tightening of the band, the second part of the housing cannot be drawn through the aperture in the end portion of the band towards the adjacent portion of the band.

An example of a clamp embodying the invention will now be described with reference to the accompanying drawing wherein: Figure 1 shows the clamp as viewed along an axis of the clamp and Figure 2 shows the clamp as viewed in a direction towards the axis, a screw and nut mechanism of the clamp being omitted.

The clamp shown in the drawings comprises a band 10 formed of metal, for example stainless steel, which is initially flat. In each of two opposite end portions 11 and 12 of the band, there is formed a rectangular aperture, one of which is shown at 13. As can be seen from Figure 2, the aperture 13 is equally spaced from the lateral edges of the band 10 and has a width approximately equal to one-half of the width of the band. The aperture is spaced from the end of the band by a greater distance, typically by a distance which is somewhat less than the width of the band but greater than one-half thereof. The length of the aperture is appoximately equal to the width of the band.

The end portion 11 is turned back over an adjacent portion 14 of the band, the band being bent at a position spaced slightly from the aperture 13 so that there is a relatively small area of the end portion 11 situtated between the bend 15 and the aperture 13.

The end portion 12 is bent back to overlie and adjacent portion 16 of the band in a similar manner.

The band is then bent to an arcuate shape such that there is a narrow gap between the bend 15 and the corresponding bend 17 which connects the portions 12 and 16.

For contracting the band to reduce the gap between the bends 15 and 17, there is provided a screw and nut mechanism comprising a hexagonal headed screw 18, a washer 19 and a nut 20, both of which are carried on a threaded shank 21 of the screw. The shank extends through housings 22 and 23 associated one with each of the end portions 11 and 12.

The housing 22 comprises a radially outer part 24 which, when viewed circumferentially of the band as shown in Figure 2, has a U-shaped cross section. The outer part lies mainly radially outwardly of the end portion 11 with the limbs of the U projecting through the aperture 13. An inner part of the housing comprises two flanges, one projecting laterally outwardly from each limb of the U-shaped outer part.

The flanges lie between the end portion 11 and the adjacent portion 14 of the band. One flange only of the housing 22 can be seen in Figure 1 and is indicated by the reference numeral 25.

The flanges of the housing 22 have a length approximately equal to that of the end portion 11 and extend from the bend 15 to the free end of the portion 11. The portion 11, the flanges of the housing 22 and the portion 14 of the band are united with one another by fusion at positions 26 and 27 spaced somewhat along the band from the aperture 13.

The length of the outer part 24 of the housing 22 is only slightly greater than the length of the aperture 13. Adjacent to the bend 15, the outer part projects circumferentially of the band slightly beyond the flanges of the housing to overlie the outwardly facing surface of the end portion 11. An opposite end of the outer part abuts a surface of the end portion 11 defining an end of the aperture 13. This arrangement ensures the outer part 24 of the housing cannot be drawn through the aperture 13 towards the portion 14 of the band when the clamp is tightened. Since the flanges of the housing are trapped between the end portion 11 and adjacent portion 14 and are united by fusion with these portions, the radially inner part of the housing cannot be drawn through the aperture 13 in a direction away from the portion 14 of the band.

The limbs of the outer part 24 of the housing engage the lateral boundaries of the aperture 13 and the end portion 11 thereby prevents the limbs of the outer part of the housing moving away from each other when the clamp is tightened.

The housing 23 is identical with the housing 22 and is arranged in a corresponding manner.

It will be noted that the positions 26 and 27 are readily accessible by welding electrodes or the like and for inspection of finished welds. The outer parts of the housings 22 and 23 are aligned with each other to receive the shank 21 of the screw and present in directions away from each other respective parallel abutment surfaces for enagagement one by the head of the screw 18 and the other by the washer 19. These abutment surfaces are perpendicularto the axis of the shank 21. It will be noted that the screw and nut are of special form and that many common forms of screw and nut could be used in the clamp.

The flanges of the housings 22 and 23 abut the band 10 atthe inside ofthe bends 15 and 17. It will be noted that the portion of the band which extends between these bends is not interrupted by any apertures or the like which would weaken the band.

The clamp is suitable for use in situations where a high tension is required to be established in the band. For example, the clamp can be used for contracting a slotted end portion of a steel tube.

When a clamp is used for this purpose, it is important that the unslotted part of the tube should not restrict contraction of the clamp. The clamp shown in the accompanying drawings has the advantage of a fairly narrow band which can be confined to the slotted part of the tube even in a case where the slots in the tube are short.

The housing 22 and 23 each have a length which is greater than the diameter of the shank 21 of the screw but does not exceed three times that diameter.

Preferably, the length of each housing is approximately twice the diameter of the shank. The width of the flanges of the housing is preferably within the range one to two times the radius of the shank 21.

Claims (9)

1. A clamp comprising a band which, in use, extends around a body or an assembly of bodies to be clamped and a screw and nut mechanism for tightening the band, wherein opposite end portions of the band are turned back over respective adjacent portions of the band, are secured to said adjacent portions of the band and are formed with respective apertures and wherein there is associated with each end portion a respective housing for receiving the screw of said screw and nut mechanism, a first part of the housing being trapped between the end portion and said adjacent portion of the band and a second part of the housing protruding through the aperture in the end portion to receive the screw.

2. A clamp according to claim 1 which comprises, in addition to the screw and nut mechanism, three components only, namely the band and two housings.

3. A clamp according to claim 1 or claim 2 wherein the length of each end portion of the band excceds the length of the second part of the associated housing and the end portion is united by fusion with the adjacent portion of the band at a position spaced circumferentially of the band from the second part of the housing.

4. A clamp according to any preceding claim wherein the first part of the housing is united by fusion with the band.

5. A clamp according to claim 4 as appendant to claim 3 wherein the first part of each housing is united by fusion with the band at said position spaced circumferentially of the band from the second part of the housing.

6. A clamp according to any preceding claim wherein the first part of each housing comprises a pair of flanges which extend in opposite lateral directions from the second part of the housing.

7. A clamp according to any preceding claim wherein the second part of each housing overlies a surface of the associated end portion of the band in a region adjacent to one end of the aperture therein.

8. A clamp substantially as hereinbefore described with reference to and as shown in the accompanying drawing.

9. Any novel feature or novel combination of features disclosed herein or in the accompanying drawing.