GB2282177A

GB2282177A - Scaffold clamp.

Info

Publication number: GB2282177A
Application number: GB9319770A
Authority: GB
Inventors: Jing Wang; Henry He Cheng Sun; Desmond Weng Kiong Lau; Shao Qin Zhang; Chong Ngang Koh; Li Lu
Original assignee: STANDARDS INST SINGAPORE
Current assignee: STANDARDS INST SINGAPORE
Priority date: 1993-09-24
Filing date: 1993-09-24
Publication date: 1995-03-29
Anticipated expiration: 2013-09-24
Also published as: SG47879A1; AU7841894A; FI961335A0; HU9600721D0; WO1995008477A1; NO314029B1; NO961178D0; RU2132807C1; GB9319770D0; CN1134135A; CA2172545A1; CN1046114C; GB2282177B; HU219048B; KR100302527B1; HUT76361A; SK38196A3; CZ86196A3; NO961178L; KR960704757A

Abstract

A scaffold clamp for clamping onto a length of tubing 30, which clamp comprises at least one jaw member 3, 4 for enclosing the circumference of the tubing and engaging a contoured outer surface 31 of the tubing, the at least one jaw member having a contoured inner engaging surface for registering with the contoured outer surface, thereby preventing translational movement of the clamp along the length of tubing. The inner surface can be provided by an insert. Also disclosed is a clamp having an insert providing a friction lining to grip a smooth surfaced tube, (left hand side of fig 1). <IMAGE>

Description

"Improvements in or relating to scaffolding" The present invention relates to a scaffold clamp and a coupling system using the scaffold clamp for use in constructing scaffolding structures.

In conventional scaffolding structures it is a common practice to construct the upright members, horizontal members and braces using aluminium, steel or metal alloy tubing having a smooth outer surface. Such tubing is heavy and it would be advantageous to use a lighter alternative such as a plastics tube made from, or including, for example, carbon fibre, fibreglass or aramid.

However, conventional clamps, when tightened upon such tubing, causes the tubing to deform or crack as the tubing is unable to support high compressive radial loads.

Accordingly, the present invention provides a scaffold clamp for clamping onto a length of tubing, which clamp comprises at least one jaw member for enclosing the circumference of the tubing and engaging a contoured outer surface of the tubing, the at least one jaw member having a contoured engaging surface for registering with the contoured outer surface, thereby preventing translational movement of the clamp along the length of tubing.

Another aspect of the present invention provides a scaffold clamp for clamping onto a length of tubing, which clamp comprises at least one jaw member for enclosing the circumference of the tubing, the at least one jaw member having an inner friction lining including an engaging surface for engaging with a smooth outer surface of the tubing, in which arrangement the frictional force between the lining and the tubing prevents translational movement of the clamp along the length of tubing.

A further aspect of the present invention provides a scaffolding structure comprising at least one scaffold clamp according to the present invention in combination with at least one length of tubing.

In order that the present invention may be more readily understood, embodiments thereof will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a perspective view of two scaffold clamps embodying the invention coupled together to constitute a coupling joint, both scaffold clamps of the coupling joint being shown in a closed configuration, the left hand scaffold clamp embodying one aspect of the present invention for clamping onto smooth tubing and the right hand scaffold clamp embodying another aspect of the present invention for clamping onto contoured or corrugated tubing; Figure 2 is a side view of a coupling joint in which both scaffold clamps are fitted with inserts and one of the scaffold clamps is shown in partial cross section to illustrate the profile of its insert;; Figure 3 is a perspective view of the coupling joint of Figure 1, one of the scaffold clamps being shown in the open position; Figure 4 is a perspective view of an insert for use with a scaffold clamp embodying the one aspect of the present invention Figure 5 is a side view of a tube for use with the right hand side scaffold clamp of Figure 1; and Figure 6 is a cross section through a scaffold clamp embodying the present invention and a tube held by the scaffold clamp.

Figure 1 shows a coupling joint 1 comprising two scaffold clamps 2. Each scaffold clamp 2 is generally cylindrical in form and comprises two semi-cylindrical jaw members 3, 4 which are joined together by a hinge 5 formed along two edges 6, 7 which extend axially along the clamp 2. The clamp 2 is hingeable from a closed position (shown in Figure 1), in which the two semi-cylindrical jaw members 3, 4 form a cylinder, to an open position (shown in Figure 3) in which the two jaw members 3, 4 are fully hinged apart.

When in the closed position, the two jaw members 3, 4 can be locked together by a locking nut 8 and bolt 9 and a clasp 10. The bolt 9 is hingedly mounted on an outer surface 11 of one jaw member 3 and the clasp 10 is rigidly mounted on an outer surface 12 of the other jaw member 4.

The clasp 10 is adapted to receive the bolt 9 in a slot 13 such that the nut 8 can be threaded down the bolt 9 to come into contact with, and lock against, the clasp 10. Figure 1 shows both scaffold clamps 2 in the closed and locked position, the two jaw members 3, 4 of each clamp 2 being locked by their respective locking nut 8 and bolt 9 onto their respective clasp 10.

To unlock the two jaw members 3, 4 the locking nut 8 is threaded away from the clasp 10 and then the bolt 9 is hinged out of the slot 13. The jaw members 3, 4 can then be moved apart into the open position shown in Figure 3.

Both axial ends of each jaw member 3, 4 are formed with annular lips 14, 15 which face radially inward. Thus, an inner surface 16 of each jaw member 3, 4 is bounded at its axial ends by the lips 14, 15. An insert 17, shown separately in Figure 4, conforms to the shape of the inner surface 16 of each of the jaw members 3, 4 and an insert 17 is securely fastened onto each of the inner surfaces 16 of the jaw members 3, 4 by adhesive or other means. The inserts 17, as well as being secured by adhesive or other means to the jaw members 3, 4 are prevented from moving axially with respect to the jaw members 3, 4 by means of the lips 14, 15 which abut two opposite ends 18, 19 of both of the inserts 17.

An insert 17 has two main surfaces. An outer surface 20 is convex and conforms to the shape of the inner surface 16 of the jaw members 3, 4 to which it is fastened.

The other surface 21 is opposite the convex surface 20 and is concave. The concave surface 21 is formed with a plurality of regularly spaced apart ribs 22 which define grooves 23 therebetween. The ribs 22 and grooves 23 run parallel with the inwardly turned lips 14, 15, that is annularly around the concave surface 21 and perpendicularly to the axial direction. When the clamp 2 is in the closed position, the ribs 22 and grooves 23 define substantially circular corrugations within the clamp 2. The ribs 22 in the insert 17 in one jaw member 3 are disposed opposite to and are aligned with the ribs 22 in the other jaw member 4 to which the first jaw member 3 is hinged. The same applies to the grooves 23.

The above described scaffold clamp 2 is particularly suited for use with a composite tubing 30 having a contoured or corrugated outer surface 31. A length of such a tube 30 is shown in Figure 5. The corrugations 32 on the tubing 30 are formed at regular intervals along the tubing 30 and this interval corresponds to the interval between the regularly spaced apart ribs 22 of the inserts 17 of the scaffold clamp 2.

To hold the composite tubing 30 formed with the corrugations 32, the clamp 2 is placed in the open position and the ribs 22 and grooves 23 of one insert 17 are registered with the corrugations 32 of the tubing 30. The jaw member 4 holding the other insert 17 is closed around the tubing 30, thereby fully encircling the circumference of the tubing 30. All the ribs 22 and grooves 23 of both inserts 17 are then registered with the corrugations 32 of the tubing 30. The locking nut 8 and bolt 9 and clasp 10 are used to lock the clamp 2 in this closed position. As can be seen from Figure 6, it is possible to use corrugated tubing 30 having a profile which is complementary to that of the profile defined by the inserts 17, thus evenly spreading any loads placed on the scaffold clamp 2 onto the tubing 30. Because of the corrugated form of the outer surface 31 of the tubing 30 in combination with the ribs 22 and grooves 23 formed in the inserts 17, the clamp 2 cannot move axially with respect to the tubing 30 but is capable of rotation around the tubing 30. Thus, there are no undue compressive stresses around the tubing 30 to cause any deformation of the tubing 30 which would otherwise occur when using conventional scaffold clamps. If the locking nut 8 is tightened further onto the clasp 10 then the ability of the clamp 2 to rotate about the tubing 30 can also be removed.

As shown in Figure 1, two scaffold clamps 2 can be rotatably joined together such that tubing held in respective clamps 2 can be arranged at desired angles to one another, for example, when constructing scaffolding.

Of course, scaffold clamps 2 could be fixed to one another with predetermined angular settings such as 450, 900 and 1800. Scaffold clamps 2 can also be fixed to other items such as masonry pins for attachment to buildings or can be formed with detachable elements to facilitate interchangeability of items.

In one embodiment of the clamp 2, the profile of the insert 17 is determined by finite element analysis to avoid any stress concentrations.

Preferably, the inserts 17 are manufactured from nylon although other materials having similar strength characteristics to nylon and suitable chemical resistance have also been envisaged such as Acrylonitrile-butadienestyrene copolymers (ABS), Polyethylene terephthalate (PET), and Polyphenylene oxide (PPO). The other parts of the scaffold clamp 2 such as the jaw members 3, 4 are preferably made from mild steel, aluminium or the like, although such other parts could be made from thermoplastic or thermosetting matrix composites.

In an embodiment of the present invention not shown in the drawings, the annular ribs 22 defined in the insert 17 may be replaced with a single or multi-start thread, thereby enabling rotation of the scaffold clamps around the tubing to move the scaffold clamp 2 either up or down the tubing 30 as desired.

In another aspect of the present invention, and as embodied in the left hand side scaffold clamp 2 of Figure 1, a scaffold clamp 2 similar to the right hand side scaffold clamp is provided which has, instead of insert 17, an elastomer lining 40 made from, for example, high shear strength hard rubber. The elastomer lining 40 is attached to the inner surface 16 of the jaw members 3, 4 by adhesive or other means. This scaffold clamp 2 is for use with tubing 30 having a smooth outer surface unlike the contoured or corrugated outer surfaces 31 previously discussed. When the jaw members 3, 4 of this scaffold clamp 2 are tightened in the closed configuration, the frictional force between the elastomer lining 40 and the outer surface of the tubing prevents translational movement of the scaffold clamp 2. As shown in Figure 1, this scaffold clamp 2 can be used in combination with the scaffold clamp for use with contoured or corrugated tubing to constitute a coupling joint 1.

Claims

CLAIMS:

1. A scaffold clamp for clamping onto a length of tubing, which clamp comprises at least one jaw member for enclosing the circumference of the tubing and engaging a contoured outer surface of the tubing, the at least one jaw member having a contoured engaging surface for registering with the contoured outer surface, thereby preventing translational movement of the clamp along the length of tubing.

2. A scaffold clamp according to Claim 1, wherein the contoured engaging surface has a profile which is complementary to that of the contoured outer surface of the tubing.

3. A scaffold clamp according to Claim 1 or 2, wherein the engaging surface comprises one or more corrugations.

4. A scaffold clamp according to any one of Claims 1 to 3, wherein the engaging surface comprises a screw thread.

5. A scaffold clamp according to any preceding claim, wherein the engaging surface is made from a material having similar strength characteristics to nylon and having chemical resistance.

6. A scaffold clamp according to any one of Claims 1 to 4, wherein the engaging surface is made from nylon.

7. A scaffold clamp for clamping onto a length of tubing, which clamp comprises at least one jaw member for enclosing the circumference of the tubing, the at least one jaw member having an inner friction lining including an engaging surface for engaging with a smooth outer surface of the tubing in which arrangement the frictional force between the lining and the tubing prevents translational movement of the clamp along the length of tubing.

8. A scaffold clamp according to Claim 7, wherein the lining is an elastomer lining.

9. A scaffold clamp according to Claim 8, wherein the lining is made from high shear strength hard rubber.

10. A scaffold clamp according to any preceding claim, wherein the clamp comprises two semi-cylindrical jaw members.

11. A scaffold clamp according to Claim 10, wherein the two semi-cylindrical jaw members are hinged together along two adjacent edges and, when in a closed configuration, are lockable along the other two adjacent free edges to enclose the circumference of the tubing.

12. A scaffold clamp according to any preceding claim, wherein the engaging surface is formed on an insert which is attachable to an inner surface of the at least one jaw member.

13. A scaffold clamp according to Claim 12, wherein the at least one jaw member is provided with means to engage the insert to prevent translational movement of the insert with respect to the jaw member.

14. A scaffold clamp according to any preceding claim, wherein the clamp is connected to another clamp to form a coupling joint for coupling together two lengths of tubing.

15. A scaffold clamp according to Claim 14, wherein the two tubing clamps of a coupling joint are pivotally connected together.

16. A scaffolding structure comprising at least one scaffold clamp according to any preceding claim in combination with at least one length of tubing.

17. A scaffold clamp substantially as hereinbefore described with reference to and as shown in Figures 1 to 4 and 6.

18. Any novel feature or combination of features disclosed herein.