GB2115476A - Clamping means and wall formwork - Google Patents

Abstract

A clamp comprises first (24) and second (25) members and tensioning means (46, 47) extending between them. Each of the first and second members (24, 25) has an abutment surface (41, 26) to engage an article such as a beam (17) to be clamped. Two tensioning elements such as bolts (46) and (47) extend between the members (24, 25) the first (47) holding the members together before use and the second (46) being used to tighten the clamp on the beam (17). The first clamp member (24) has an abutment surface (41) formed by two mutually inclined surfaces (42, 43) which provide a fulcrum (44). The fulcrum is approximately half the distance from tensioner (47) that it is from tensioner (46). Preferably the tensioner (47) is screwed in to a set extent at the factory, leaving only (46) to be tightened on site. The clamp is designed to support shuttering (10, 11, 12 and 13) in wall formwork. <IMAGE>

Description

SPECIFICATION Clamping means This invention relates to clamping means comprising first and second members and tensioning means extending between the members to urge them into clamping relationship with an article disposed therebetween.

The strength of the clamped connection thus produced is dependent upon the tension existing in the tensioning means and this leads to the need to provide a plurality of tensioning means where high clamping strength is required. For example, where the tensioning means comprise a number of threaded fasteners and associated nuts, the time involved in tensioning all the fasteners is excessive.

The present invention seeks to provide a new or improved clamping means whereby the above mentioned problem is overcome or is reduced.

According to one aspect of the invention, we provide a clamping means comprising first and second members and tensioning means, the first and second members each having an abutment surface to engage an article to be clamped, the tensioning means comprising first and second tensioning elements extending between the members, the abutment surface of the first member having a portion, intermediate the first and second tensioning elements, which provides a fulcrum positioned closer to the first tensioning element.

The first tensioning element may be arranged to limit movement of said members away from each other and the second tensioning element may be arranged to urge the first and second members together.

Thus, a tensioning force developed, in use, in the second tensioning element is magnified, by the ratio of the distance between the first and second tensioning members and the distance between the fulcrum and the first tensioning member and which is applied to the said article at said fulcrum.

The first and second tensioning elements may each have a first abutment to engage with the first member and a second abutment to engage with the second member, and a shank extending between the two abutments, the shank of the first tensioning element being of fixed length between the abutments, and the length of the shank of the second tensioning element between the abutments being adjustable. Examples of such first tensioning elements are fasteners such as rivets, studs or the like, or the first and/or second abutments may be provided by welding an element such as a nut, on the shank.

The second tensioning element may comprise a fastener the first or second abutment comprising a head which engages the first or second member respectively, and the shank may be male threaded to co-operate with a female threaded element providing the second or first abutment and being associated with the second or first member respectively.

Of course the head could comprise an enlarged end of the shank or another female threaded element engaged with the male threaded shank, and the first mentioned female threaded element may comprise a nut or the like, or a threaded receiving formation, such as a bore, of the second or first member respectively.

Instead of the shank of the first tensioning element between the abutments being of fixed length, if desired the first tensioning element may also comprise a fastener, having a head which engages the first or second members and a male threaded shank which co-operates with a female threaded element associated with the second or first member respectively.

The abutment surface of the first member may comprise two relatively inclined planar portions which intersect at said fulcrum although if desired, the abutment surface may comprise two curved portions which intersect at said fulcrum.

Preferably, the fulcrum is located at a position on the abutment surface of the first member about one third of the distance between said first and second tensioning elements.

Thus, using such a clamping means, only one third of the total tensioning force is carried by said second tensioning element which can thus be made smaller or in some other way less strong than the first tensioning element, thereby minimising costs.

The invention has been particularly developed for use in wall formwork although it has many other applications.

According to a second aspect of the invention, we provide a formwork comprising a shuttering element to which is clamped a clamping means according to the first aspect of the invention.

The formwork may comprise a pair of mutually inclined shuttering elements and beams, usually inclined at 900, a bracket assembly clamped to each beam and a tie rod extending between the bracket assemblies to limit movement of the beams and hence the shuttering elements away from one another, wherein each bracket assembly includes a clamping means whereby the bracket assembly is clamped to a beam.

By virtue of the clamping of the bracket assembly to the beam, when the tie rod is tensioned, the clamping action effected by the present invention is able to resist the component of force developed by the tie rod which extends parallel to the longitudinal axis of the beam.

Since, in formwork, such as wall formwork, it is not always possible to predict where the bracket assemblies have to be positioned on the beams, it is necessary to provide a clamping means to attach the bracket assembly to the beams at any required position along the beams and the present invention provides a clamping means which is very suitable for the purpose, particularly as with a conventional bolted clamping assembly several bolts would be required to achieve the magnitude of resistance required in such situations and this would take up considerable time and effort on assembly and disassembly.

The first member of the clamping means of the bracket assembly may be positioned on one side of a co-operating part of the beam and the second member may be positioned on the opposite side of said co-operating part of the beam to clamp said part of the beam therebetween in use.

The tie rod may be connected to the second member of at least one of said bracket assemblies through a formwork soldier.

The second member may have a second abutment surface inclined to the first abutment surface, which second abutment surface lies normal to the longitudinal axis of the tie rod.

The soldier may be secured to the second abutment surface by a securing means such as a scaffold bolt.

The invention will now be described in more detail by way of example, with reference to the accompanying drawings, wherein: FIGURE 1 is a plan view, partly broken away, of a corner of a wall formwork embodying the invention; FIGURE 2 is a perspective view, partly broken away, of part of a bracket assembly used in the formwork shown in Figure 1; FIGURE 3 is a perspective view of another part of the bracket assembly; FIGURE 4 is a section on the line IV-lV of Figure 3; and FIGURE 5 is a perspective view of a soldier clamp used in the formwork of Figure 1.

Referring to the drawings, a corner of a wall formwork is illustrated in Figure 1 and comprises a pair of inner shuttering elements comprising panels 10, 11 and a pair of shuttering elements comprising panels 1 2, 13 between which concrete is to be cast to provide a pair of mutually perpendicular walls.The inner panels 11 are supported by beams 14, 1 5 and the outer panels are supported by beams 16, 1 7. Soldiers 1 8 engage the beams 14, 1 5 whilst soldiers 1 9 engage the beams 1 6, 1 7 and tie rods (not shown) extend between and engage the soldiers 1 8, 19 in conventional manner and can be tensioned to limit movement of the beams 14, 16 and 15, 17 and hence panels 11, 13, away from each other.

In order to support the shuttering panels 12, 13 adjacent the outer corner 20 of the formwork, it is necessary to provide a tie rod (not shown) which extends so that its longitudinal axis is inclined at an angle of 450 to the shuttering panels 13, 14 and hence to the beams 1 6, 17.

The tie rod passes through the soldiers 22 and restrains them from moving apart by means of a washer plate and nut assembly 22a at the outer faces thus limiting movement of the beams 16 and 1 7 and hence shuttering panels 12, 13 away from one another. The soldiers 22 are clamped to a bracket assembly 23, and the bracket assembly 23 is clamped to its associated beam 1 6, 1 7.

Alternatively, the soldiers may be omitted and the tie rod connections made direct to the bracket 23 with the tie rods passing through slots 35.

The bracket assemblies 23 are identical to each other and each comprise a first clamping member 24 and a second clamping member 25. The second clamping member 25 is of angle configuration having a first abutment surface 26 which engages the associated beam 1 6, 1 7, and a second abutment surface 27 which engages the soldier 22. The first and second abutment surface 26 and 27 comprise outwardly facing surfaces of inclined generally laminar parts 26a, 27a respectively of the angle bracket which are interconnected by generally triangular web portions 29 and the angle bracket is strengthened by gussets 30 and ribbing 31.The part 27a is provided with a pair of slots 35 which may each receive securing means comprising a soldier securing or scaffold bolt 36 and a central aperture 35a is also provided which may, instead of or in addition to slots 35, receive a bolt 26. In the drawing, a bolt 36 is only shown in aperture 35a.

Surrounding the aperture 35a, a pair of spaced parallel upstanding ribs 32 are provided to engage flats on the head of the bolt 36 to prevent rotation thereof.

The bolt 36 or bolts are used to secure the bracket assembly 23 to a soldier 22 as hereinafter explained.

The part 26a has a pair of apertures 37, 38, the aperture 37 being smaller than the aperture 38, to receive tensioning elements which in the example shown, each comprise bolts 46, 47, the headed ends of which provide first abutments and are engaged in correspondingly sized bores 39, 40 formed in the first clamp member 24, see Figures 3 and 4. Ribs 34 surround the apertures 37, 38 to engage the flats on the heads of the bolts 46, 47 to prevent rotation thereof.

The beams 1 6, 1 7 and the soldiers 22 each have a longitudinally extending slot 5 in the part thereof engaged by the second clamping member 25 and bolts 46, 47 project through the holes 39, 40 and extend through the slot 5.

The first clamp member 24 has an abutment surface 41 comprising two planar portions 42,43 which are mutually inclined and intersect to provide a fulcrum 44. In addition, the member 24 has a depending lug 45 of a width so as to engage in the slots 5 of the beam 16 or 17 and so locate the clamp in use. The fulcrum 44 is positioned, as best shown in Figure 4, at a distance from the larger bore 40 which is approximately one third of the distance between the bores 39, 40 and hence bolts 46, 47.

Female threaded elements comprising nuts, are received on the threaded shanks of the bolts 46, 47, and provide second abutments to engage the second clamping member 25.

Each bracket assembly 23 is assembled with the bolts 46, 47 loose, slid along the length of the associated beam 1 6 or 1 7 to the desired position and the nut on the bolt 47 is then tightened to a desired tension.

Preferably, the nut of the bolt 47 is preadjusted in the factory to the desired tension by, for example, assembling the first and second clamping members together, engaging a nut on the bolt 46 at the free end of the threaded shank thereof and then tightening the nut of the bolt 47 until the end of the lug 45 is pressed against the surface 26. The length of the lug 45 is such that such pre-setting provides a correct spacing to receive the beam in use.The nut on the bolt 47 may be secured in this pre-set position by welding or by a locknut, or other means, so that the length of the shank between the head and the nut, is fixed, or the bolt 47 may be replaced by a fastener having a head, i.e. enlarged shank, fixed nut or other abutment at each end, such as a rivet, stud or the like with one head for engagement with member 24 and the other head for engagement with member 25, again the length of the shank between the heads being fixed.

The nut and bolt connection 46 is then tightened to achieve the desired tension thereby adjusting the length of the shank between the head of bolt 46 and the associated nut.

Because of the disposition of the fulcrum 44 at one third of the distance between the fasteners 46, 47, from the fastener 47 the total force applied to the beam at the fulcrum 44 is distributed between the fasteners 46, 47 so that the fastener 46 carries only one third of the total load and the fastener 47 two thirds of the total load. The fastener 46 can thus be made smaller or in some other way less strong than the fastener 47 thereby reducing costs. In addition, because only one fastener has to be tightened, clamping of the bracket assembly to the beam is facilitated.

When the bracket assemblies have been thus clamped to their associated beams, the soldiers 22 are secured to the second abutment surfaces of the bracket assemblies in conventional manner using the soldier securing bolts 36 and conventional soldier securing plates 33. Where a soldier has a longitudinally extending slots such as the soldiers 22 shown in the Figures, the soldier securing plates 33 are orientated so that the surface 33a of each faces towards the second clamping member 25, and a bolt 36 is engaged with each of the plates 33 through the slots 35 and/or aperture 35a. Each plate 33 is then disposed with its parallel side portions 33b aligned with the slot so as to be passed therethrough.Thereafter, the plate 33 is rotated to bring wing portions 33c into overlying relationship with the soldier so that on tightening of the bolt 26 the soldier is clamped to the second clamping member 25.

Where a soldier has a longitudinally extending slot bounded by lips, the plate 33 is orientated so that the lips can engage in the slots 33d on the face 33a of the plate, and after the plate has been engaged with a bolt similar to the bolt 36, the clamp 33 and second clamping member 25 are slid longitudinally of the soldier with the lips thereof engaged in the slots 33d and thereafter the bolt 36 is tightened to again secure the soldier 22 to the second clamping member 25.

Although the clamping means described above are an integral part of a bracket assembly for an inclined corner tie rod of a wall formwork, the clamping means of the present invention can be used in any other applications where it is desired to clamp two members together with tensioning means extending therebetween.

For example, the clamping means may be used in a bracket assembly having two abutment surfaces 26 and 27 at angles other than the 450 angle shown, so that for example, the brackets may be used for formwork corners other than at 900, such as triangular formwork, or the abutment surfaces 26 and 27 may be mutually perpendicular to one another for connecting a member such as a formwork soldier at right angles to another member such as a formwork beam.

In a formwork application, the soldiers 22 may be replaced by any other type of formwork soldier, although preferably the type of soldier used has a central slot such as slot 5 to receive bolts 36 at an infinite number of positions along the length of the soldier, although if desired, where no slot is provided, apertures may be made in the soldier through which the bolts 36, or other securing means may pass.

If desired, a tie rod need not engage a soldier as described, but could for example directly engage at one or both ends, a part provided by the bracket assembly or assemblies, in which case, one or both of the soldiers may be omitted altogether.

The invention is not limited to the bolt 46 engaging with a nut but if desired, instead of a nut a female threaded bore may be provided in the first or second clamping member 24, 25 whilst the head of an associated bolt engages the second or first clamping member 25, 24 respectively.

As described above, the bolt 47 could be replaced by any other type of fastening which prevents the members 24, 25 moving apart at that side of the fulcrum 44. The bolt 46 may also be replaced by any other tensioning element to draw members 24, 25 together at that side of the fulcrum.

Although as described, the fulcrum is one third of the distance between the two elements 46 and 47, if desired this ratio may be altered, although it is essential that the fulcrum is positioned closer to the tensioning element 47.

Claims (18)

1. A clamping means comprising first and second members and tensioning means the first and second members each having an abutment surface to engage an article to be clamped, the tensioning means comprising first and second tensioning elements extend between the members, the abutment surface of the first member having a portion, intermediate the first and second tensioning elements, which provides a fulcrum positioned closer to the first tensioning element.

2. A clamping means according to Claim 1 wherein the first tensioning element is arranged to limit movement of said members away from each other, and the second tensioning is arranged to urge the first and second members together.

3. A clamping means according to Claim 2 wherein the first and second tensioning element each have a first abutment to engage with the first member and a second abutment to engage with the second member and a shank extending between the abutments, the shank of the first tensioning element being of fixed length between the abutments and the length of the shank of the second tensioning element between the abutments being adjustable.

4. A clamping means according to Claim 3 wherein the second tensioning element is a fastener, the first or second abutment comprising a head which engages the first or second member respectively, and the shank being male threaded to co-operate with a female threaded element providing the second or first abutment associated with the second or first member respectively.

5. A clamping means according to Claim 1 or Claim 2 wherein the first tensioning element comprises a fastener, having a head which engages the first or second member and a male threaded shank which co-operates with a female threaded element associated with the second or first member respectively.

6. A clamping means according to any one of the preceding Claims wherein the abutment surface of the first member comprises two relatively inclined planar portions which intersect at said fulcrum.

7. A clamping means according to any one of the preceding Claims wherein the fulcrum is located at a position on the abutment surface of the first member about one third of the distance between said first and second tensioning elements.

8. A clamping means substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

9. A formwork comprising a shuttering element to which is clamped a clamping means according to any one of the preceding claims.

10. A formwork according to Claim 9 comprising a pair of mutually inclined shuttering elements and beams, a oracket assembly clamped to each beam and a lie rod extending between the bracket assemblies to limit inward movement of said beams and hence the shuttering elements wherein each bracket assembly includes a clamping means whereby the bracket assembly is clamped to a beam.

11. A formwork according to Claim 10, wherein the shuttering elements and beams of each pair are inclined at 900 to each other.

12. A formwork according to Claim 10 or Claim 11 wherein the first member of said clamping means of each bracket assembly is positioned on one side of a co-operating part of the beam and the second member is positioned on the opposite side of said cooperating part of the beam to clamp said part of the beam therebetween in use.

13. A formwork according to Claim 12 wherein said tie rod is connected to the second member of each bracket assembly.

14. A formwork according to Claim 13 wherein the tie rod is connected to the second member of at least one of said bracket assemblies through a formwork soldier.

1 5. A formwork according to any one of Claims 12 to 14 wherein the second member has a second abutment surface inclined to said first abutment surface, which second abutment surface lies normal to the longitudinal axis of the tie rod.

16. A formwork according to Claim 15 where appendant to Claim 14, wherein the soldier is secured to the second abutment surface by a securing means.

1 7. A formwork substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

18. Any novel feature or novel combination of features disclosed herein and/or shown in the accompanying drawings.