GB2083857A - Clamp - Google Patents

Abstract

A clamp for clamping a grid member 12 of a floor or catwalk to a supporting joist 14 is fitted onto the grid member and secured in position from above the floor by reaching through the bars of the floor without any need to hang over the edge of the support structure. The device comprises a hook element 26 which hooks over the top of a grid member 28a, and a clamping plate 18 which abuts the underside of a flange of the joist, and preferably also the underside of the grid member 12, Fig. 1, not shown. The hook element and the clamping plate are clamped together by a nut 22 and a bolt 20, the free end of the bolt being blocked off to retain the nut. The clamping plate may be held against horizontal rotation, once the device has been clamped by rotating the bolt, by abutment of the plate 18 against a downwardly extending portion 16 of the hook element 26. <IMAGE>

Description

SPECIFICATION Clamping device The invention relates to clamping devices and more particularly but not exclusively, to clamping devices for use in securing walkways and the like grid members to a floor support such as, for example, a joist or floor girder.

Walkways, cat walks, inspection covers and observation platforms used in industrial buildings, such as chemical plants and factories, may comprise one or more metal grid members which are secured at their outer edges to a support structure such as a joint or a girder by means of one or more clamping devices. Conventionally each clamping device comprises a top clip, a nut, a hook or a bolt and a clamping plate. In use a conventional clamp has to be assembled around the edge of a grid member and an associated support structure, and then needs to be tightened in order to clamp the grid member and the associated support structure together between the top clip and the clamping plate.

It will be appreciated that the conventional clamp sometimes comprises even more than the four components already mentioned. Thus for example, there may be one or more washers and/or one or more locking nuts. Because each conventional clamp comprises at least four components and since those components need to be assembled together before a grid member can be secured to its associated support structure, the process of securing a grid member to a support structure can be relatively time consuming. The other problem associated with this operation is that because the assembly is carried out on site pieces are often dropped and have to be retrieved or replaced; and in some cases two workers are used to fit the clamping device, one working from above, and one from below the grid member.

A subsidiary problem with conventional clamping devicesis that deflection of the flooring due to the weight of a person walking across temporarily release the clamping plate, which can move fractionally before it re-engages. With a lot of use the cumulative effect can result in the rotation of the clamping plate with respect to the support structure to the extent that the clamping member is no longer engaged with the support structure.

The present invention seeks to provide a clamping device for use in securing a grid member to a support structure which alleviates or mitigates the disadvantages associated with the conventional clamp.

According to the present invention there is provided a clamping device for use in securing a grid member to a support structure, the device comprising a hook element for engagement over the top of a grid member, an abutment member for engagement under a portion of the structure and a clamping mechanism adjustable to vary the vertical distance between the hook element and the abutment member to enable the device to be tightened to or released from the grid member and the associated support structure, wherein the hook element, the abutment member and the clamping mechanism are all held together for installation from above the grid member.

The clamping device according to the present invention is ready assembled, as opposed to a conventional clamp which needs to be assembled in situ.

Preferably the clamping device includes means for holding the abutment member in a constant angular relationship with the hook element so that there is no relative rotation in the plane of the abutment member once the device has been tightened to the structure. This means may be an upright portion connected to the hook element against which the abutment member rests, the width of the portion being sufficient to prevent sideways movement in either direction. The clamping mechanism may be adjustable to accommodate different sizes of grid member and/or support structure. The lateral position of the hook element on the abutment member may also be adjustable to enable the device to be fitted while avoiding the cross bars on the grid member.

Advantageously the clamping mechanism comprises a screw threaded member, and may comprise a screw or bolt. The clamping mechanism may also include a nut and the abutment member preferably rests on the nut so that the abutment member is adjusted along the length of the screw thread with the nut during rotation of the screw threaded member.

The screw threaded member may pass through the abutment member by means of a slot in the abutment member. This serves both to allow lateral adjustment of the hook element and enables the abutment member to tilt towards a substantially upright position to facilitate the engagement of the clamping device with the support structure and/or grid member.

The abutment member may comprise a clamping plate, which may engage also with the underside of the grid member, and the clamping plate may be bent or otherwise shaped to facilitate the engagement of the clamping device with the support structure and/or grid member.

One embodiment of the clamping device will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a side elevation of a clamping device shown in use, clamping one edge of a grid member to a support structure, Figure 2 is a plan view of the device shown in Figure 1, Figure 3 is an end view of the device shown in Figure 1, and Figure 4 is a sectional and elevation of a clamping device taken on line IV--IV of Figure 1.

A galvanised mild steel clamping device is indicated generally at 10 and is used, as shown in the accompanying-drawings, to clamp one end of a grid member 12 of a cat walk to a floor support girder 14.

The clamping device 10 comprises an upright portion 1 6 which is made from galvanised mild steel plate bent to the required shape and a clamping plate 18. The upright portion 1 6 and the clamping plate 1 8 are connected together by a screw threaded bolt 20 and a square nut 22. The upright portion 1 6 is turned over at its upper end 24 to form a hook element 26 in the form of an inverted U-shaped channel member (see figures 2 and 4) which can be hooked over a longitudinal element 28 of the grid member 12 to locate the device 10 on the grid member. The upright portion is stepped at 30 and the head 20a of the bolt 20 is located on the step 30.The bolt 20 passes through a hole 32 formed in the step 30 and the lower end of the bolt is rotatably mounted in an inturned foot 34 at the lower end of the upright portion 16.

The bolt 20 after passing through the hole 32 also passes through a slot 35 formed longitudinally in the clamping plate 1 8 (see Figure 2) to connect the clamping plate 18 to the upright portion 16. The slot 35 both enables the clamping plate to be moved to a position substantially alongside the bolt for fitting the clamping device, and also provides a lateral adjustment for the relative positioning of the hook element 26 and the abutment surface of the clamping plate 1 8 so that the best position on the girder can be selected for the hook, and cross bars can be avoided.

The square nut 22 is threaded to the portion of the belt 20 which extends between the step and the foot 34 and one edge of the square nut abuts the upright portion 1 6 to prevent the nut for rotating when the bolt 20 is turned. The clamping plate 1 8 rests on top of the upper surface of the nut. When the bolt head is rotated (for example by a screw driver or a spanner), the square nut 22 travels along the length of the bolt without rotating and the clamping plate 1 8 is thereby correspondingly raised or lowered relatively to the bolt 20 and the upright portion 1 6. The part of the upright portion 16 between the step 30 and the foot 34 together with the bolt 20 and the nut 22 form a clamping mechanism for the device. The abutment member for the support structure is formed by the clamping plate.

The clamping plate 1 8 is of inverted channel shaped cross-section and the web at the rear end 36 of the clamping plate is substantially flat.

Alternatively the clamping plate can be a shaped metal plate or bar. The forward end 38 of the clamping plate 1 8 extends to the other side of the upright portion 16, is angled upwardiy towards the front, and is rounded, as indicated at 40. The forward end rests, in use, under the grid member 12 to prodice a firmer clamping action.

In order to clamp a grid member 12 to a girder 14, the grid member is located on the girder with the edges just protruding over the upper flange 42 of the girder as shown clearly in figure 1. The channel member 26 of the clamping device 10 is then hooked over one of the longitudinal elements 28a of the grid member. During the attachment of the upright portion 16 to the element 28 the nut 22 is lowered towards the foot 34. With the nut in this position the clamping plate 1 8 has freedom for considerable movement relative to the bolt 20, and is tilted until it occupies a position alongside the bolt (i.e. its length extends downwardly), to facilitate the insertion of the clamping device 10 between adjacent cross bars 29 of the grid member 12.

The clamping device 10 is then slid along the element 28a towards the girder 14 until the rear end 36 of the clamping plate 18 engages the upper flange 42 of the girder 14 and the forward end 40 of the clamping plate engages beneath the underside of the element 28a. The bolt 20 is then rotated to raise the nut 22 and thus raise the clamping plate 1 8 towards the element 28a. As the bolt is tightened, the nut forces the forward end 38 of the clamping plate 18 into engagement with the underside of the element 28a and also urges the rear end 36 of the clamping plate into engagement with the underside of the upper flange 42 of the girder 14. The grid member 12 is thereby clamped to the girder and the cat walk can thus be secured in position.Once in position the clamping plate rests against the upright portion 1 6 for enough of its length to prevent any movement or rotation of the clamping plate around the bolt 20.

In order to release the grid member from the girder 14, the reverse procedure is followed. The bolt is rotated to loosen the nut and to allow the clamping plate 18 to move away from the upper flange 42 and the element 28a. The clamping device is then slid forwardly away from the girder 14 over the element 28a and the device 10 can then be removed from the element 28a by pivoting the clamping plate 1 8 relative to the upright portion 16, if required, to allow the clamping plate to pass between the two elements 29, and then lifting the clamping device 10 from engagement with the grid member 12.

It will be appreciated that one person working from above the grid member 12 is able to secure the member 12 to the girder 14.

It will be understood that a strong clamping action will only be gained if the distance from the top of the flat rear end 36 of the clamping plate 18 to the top of the front end 38 thereof is substantially equal to or less than the thickness of the upper flange 42, although cven where such is not the case, the device 10 may still provide sufficient clamping action to secure the grid member 12 to the girder 14.

If desired, the clamping devices could be formed in a plurality of sizes to accommodate different sizes of grid members 1 2 and/or girders 14; however, since the clamping plate 1 8 is adjustable relatively to the upright portion 1 6 by rotating the bolt 20, any one device 10 can be used to clamp a variety of different sizes of grid members and girders together.

Alternative embodiments according to the invention are also envisaged. Thus, for example, the clamping device could be formed of materials other than galvanised mild steel, such as chromed brass or plated cast iron.

Claims (12)

1. A clamping device for use in securing a grid member to a support structure, the device comprising a hook element for engaging over the top of the grid member, an abutment member for engagement under a portion of the structure and a clamping mechanism adjustable to vary the vertical distance between the hook element and the abutment member to enable the device to be tightened onto or released from the grid member and the associated support structure, wherein the hook member, the abutment member and the clamping mechanism are all held together for installation from above.

2. A clamping device according to claim 1 including means for holding the abutment member in a fixed angular relationship with the hook element so that there is no relative rotation.

3. A clamping device according to claim 2 wherein the said means is an upright extension of the hook element, which upright extension engages a length of the abutment member to hold the abutment member against relative rotation.

4. A clamping device according to claim 3 wherein the upright extension is displaced from the hook element by a stepped portion and the clamping mechanism comprises a screw threaded member which passes through apertures in the stepped portion and the abutment member and a nut captive on the screw threaded member and held against rotation with the bolt.

5. A clamping device according to claim 4 wherein the nut is square and held against rotation with the bolt by engagement with the upright extension.

6. A clamping device according to claim 4 or 5 wherein the hook element, the stepped portion and the upright extension are formed from a single sheet of material bent to the required shape.

7. A clamping device according to any of claims 4 to 6 wherein one end of the screw threaded member is contained in an inturned foot on the upright extension, the nut is located between the said foot and the underside of the abutment member and the screw threaded member includes means above the said stepped portion by which the screw threaded member can be turned to adjust the position of the nut, and hence the relative positions of the abutment member and the stepped portion.

8. A clamping device according to any of the preceding claims wherein the abutment plate includes a portion which engages the underside of the grid member when the device is in use.

9. A clamping device according to any of the preceding claims wherein the lateral position of the hook element is adjustable along the length of the abutment member.

10. A clamping device according to any of the preceding claims wherein the abutment member can be tilted with respect to the clamping mechanism to facilitate the positioning of the device on the structure on which it is to be fitted.

11. A clamping device according to claim 9 or 10 as appendant to any of claims 4 to 7 wherein the abutment member has a slot through which the screw threaded member extends and along which it can move.

12. A clamping device substantially as herein described with reference to the accompanying drawings.