GB2184060A - Clamp for a component & a pipe to be joined - Google Patents

Abstract

The clamp has a handle 12 at the top of a column 10 and a second handle 20 as part of an assembly 15 slidable along the column and lockable by a cam 50 and a lever 18. An abutment 14 at the lower end of the column engages beneath the pipe. A second abutment 22, part of the assembly 15, retains the component, which is engaged with the pipe by adjustment of the assembly along the column 10. The lever 18 is raised to lock the assembly and the handle 20 is raised to stress a spring arm 32 forcing the limb 60 and the abutment 22 downwardly. The link 40 goes to an over-centre position engaging a stop 46. The load applied to the component is indicated by a pointer 72 against a scale 74. The load is adjustable by rotation of a knob 28 and the rod 24, which has screw- threaded engagement with a nut 30. <IMAGE>

Description

SPECIFICATION Clamp for a component & a pipe to be joined The invention relates to clamps for holding together a component and a pipe to which the component is to be joined.

The invention is particularly, though not exclusively, concerned with holding a saddle or other component of, for example, polyethylene provided with an electric heating coil, so that the component can be joined to a polyethylene pipe by electrofusion. For example, such a pipe is positioned in a trench in the ground and forms part of a natural gas distribution system.

In the equipment currently available for that purpose, there is either a clamp or strap which has to be assembled completely around the pipe. This involves the risk that the clean area of the pipe prepared for the saddle or other component will be contaminated by soil from the trench in which the pipe is positioned. Another drawback is that, in order to cope with different sizes of components and pipes, a relatively large and cumbersome assembly of equipment is required.

An example of a previously-proposed clamp is described in British patent application publication No. 2105806A. The pressure under which the component engages the pipe is indicated by a pressure gauge connected to hydraulic cylinders forming part of the clamp linkage.

It has previously been proposed in British patent specification No. 604586 to apply load to a jaw of a clamp, holding shuttering in concrete construction work, using a spring rod.

The object of the invention is to provide a clamp in which the drawbacks, mentioned above, of the currently available equipment used for electrofusion are reduced or eliminated.

According to the invention, a clamp comprises a column having a first handle at its first end and at its second end a first abutment laterally offset from the column and engageabie with a first side of a pipe, and an assembly which includes a second handle towards said first end of the column and a second abutment towards said second end thereof and laterally offset therefrom, the assembly being advanceable along the column to a releasably locked position in which a component supported by the second abutment engages a second side of the pipe opposite to the first side, relative movement of the handles in a first sense stressing a resiliently deformable member the load in which is applied to the second abutment to force the component against the pipe, the assembly also including means to hold the member stressed after the handles have been released and an index element and a scale element relatively movable to indicate the load applied to the component.

Preferably, relative movement of the handles causes relative angular movement of the column and a cantilever arm about a fulcrum.

Preferably, the second abutment is on a limb which extends away from the column and which is carried by the fulcrum on the assembly, and the cantilever arm is mounted at one end on the limb between the fulcrum and the second abutment.

Preferably, the cantilever arm or part of it forms said resiliently deformable member.

Preferably, the second handle is connected to the remainder of said assembly by a link which, as the handles move relatively in said first sense, moves through a dead-centre position to an over-centre position in which it maintains said resiliently deformable member stressed.

One embodiment of clamp will now be described by way of example with reference to the accompanying drawings in which: Figure 1 is a vertical side elevation of the clamp; Figure 2 is a tranverse horizontal section on the line Il-Il; in Fig. 1 and Figure 3 is an enlarged part of Fig. 1.

The clamp consists of the following main parts: a column 10 of extruded aluminium alloy, square-U section channel; a first handle 12 at the first, upper end of the column; a first abutment 14 at the second, lower end of the column 10 provided by the lower end portion of the column formed into a hook shape.

Thus, the abutment 14 is laterally offset from the column 10; an assembly 15 including a sleeve 16 through which the column 10 extends, the position of the sleeve 16 along the column 10 being adjustable and the sleeve being releasably lockable in the range of positions by a cam lever 18. The sleeve 16 is of aluminium alloy, square-U section channel.

The assembly 15 also includes a second handle 20 towards the upper end of the column and a second abutment 22 towards the lower end of the column.

The handle 20 is freely rotatable on a rod 24 which has a screw thread 26 over part of its length. A knob 28 is fast with the rod 24 and a nut 30 runs on the thread 26. The nut 30 has a fork which receives the upper end of a resiliently deformable, cantilever spring arm 32. The arm 32 is connected to the fork by a pivot pin 34.

The rod 24 is freely rotatable in a stopassembly 36. The stop-assembly 36 is connected by a pivot pin 38 to one end of a link 40. The other end of the link 40 is connected by a pivot pin 42 to a block 44 mounted between two side walls of a square-U section channel piece 45 welded to opposite sides of the sleeve 16. The stop-assembly 36 includes a web 46 which is engaged by the link 40 as explained below.

The block 44 carries a cam 50 pivotted on a pin 52 and integral with the lever 18. The cam 50 acts on a lock-plate 54 mounted on a pivot pin 56 on the block 44. The plate 54 is pushed by the cam 50 through an opening in the sleeve 16 against the column 10.

The second abutment 22 is adapted to fit into and retain a component such as a "tee" component housing a saddle-shaped formation in which an electric heater coil is embedded.

The abutment 22 is carried by a limb 60 and is retained by a pivot pin 62 in a fork at the limb end. The other limb end is conencted by a pivot pin 64 to a pair of lugs 66 on the sleeve 16. The abutment 22 is thus opposed to the first abutment 14 and is laterally offset from the column and positioned towards the second lower end of the column.

The limb 60 is a bar which has a larger diameter, inclined through-bore in which the lower end of the cantilever arm 32 is received. A set-screw 68 retains the arm 32.

The limb 60 has a smaller diameter throughbore parallel to the larger bore in which the lower end of an index element, in the form of an additional arm made up of a rod 70, is received. The rod 70 is retained by another set-screw (not shown) opposite the screw 68.

The rod 70 has a pointer 72 at its upper end, which moves over a scale element 74 carried by the arm 32.

The lugs 66 are the side walls of a square U section channel piece 80 welded to the sleeve 16. The base of the channel piece 80 and the base of the channel piece 45 extend across the open mouths of the channel sections of the sleeve 16 and the column 10, so retaining the sleeve 16 upon the column 10.

OPERA TION The clamp will usually be used in the upright position shown in the drawings. With the cam lever 18 depressed to release the lockplate 54, the assembly 15 can be moved up or down the column 10 to suit the size of pipe and component to be joined to the pipe.

The component of polyethylene, typically, is mounted on the upper abutment 22 and the lower abutment is passed beneath the horizontal exposed polyethylene pipe exposed polyethylene in its trench or other excavation.

The assembly 15 is locked in a suitable position by lifting the lever 18 so that the component properly seats against the upper side of the pipe, the handle 20 being in its lowermost position as shown in Fig. 1.

The handle 20 is next raised towards the handle 12. The cantilever arm 32 and the limb 60 are forced to turn about the fulcrum 64 in clockwise sense as shown in Fig. 1. The pin 38 and the link 40 move down to a deadcentre position in which the link 40 is aligned with the rod 24. Slight further upward movement of the handle 20 forces the pin 38 and the link 40 down past the dead-centre position to an over-centre position in which the link 40 abuts the lower edge of the end of the web 46 of the stop-assembly 36. This position is stable and the component is held safely against the pipe under a force determined by the stress in the deflected spring arm 32 and indicated by the pointer 72 against the scale 74. If the force requires adjustment, the operator turns the knob 28 to rotate the rod 24 in the nut 30.The nut moves along the rod changing the stress in the arm 32 until the required force is indicated on the scale 74.

Once the knob 28 has been correctly adjusted for a given size of component and pipe, and provided the component is first properly seated against the pipe before the handle 20 is raised, the operator can use the clamp repeatedly, without further adjustment, the required force being exerted on each successive component to be joined to the pipe. This greatly facilitates the joining of long 'runs' of identical components to the pipe.

The clamp can be used in inclined or horizontal position, for example, to hold a component to be joined to the pipe in a position other than on top of the pipe.

The clamp is compact and light in weight. It requires only a narrow excavation to uncover a previously buried pipe to which a component is to be joined.

In the clamp described above with reference to the drawings, the movement of the handle 20 away from the first abutment 14 is believed to represent an optimum mode of operation so far as the operator is concerned. Although other modes of operation are feasible in modified clamps within the scope of the invention, it is believed that the operator will experience less fatigue and find manipulation of the clamp more convenient using the dispositions and action of the handles as in the embodiment described by way of example above.

CLAIMS 1. A clamp for holding together a component and a pipe to which the component is to be joined comprising a column having a first handle at its first end and at its second end a first abutment laterally offset from the column and engageable with a first side of a pipe, and an assembly which includes a second handle towards said first end of the column and a second abutment towards said second end thereof and laterally offset therefrom, the assembly being advanceable along the column to a releasably locked position in which a component supported by the second abutment engages a second side of the pipe opposite to the first side, relative movement of the handles in a first sense stressing a resiliently deformable member the load in which is ap plied to the second abutment to force the component against the pipe, the assembly also including means to hold the member stressed after the handles have been released and an index element and a scale element relatively movable to indicate the load applied to the component.

2. A clamp according to claim 1, in which relative movement of the handles causes relative angular movement of the column and a cantilever arm about a fulcrum.

3. A clamp according to claim 2, in which the second abutment is on a limb which extends away from the column and which is carried by the fulcrum on the assembly, and the cantilever arm is mounted at one end on the limb between the fulcrum and the second abutment.

4. A clamp according to claim 3, in which the cantilever arm or part of it forms said resiliently deformable member.

5. A clamp according to claim 3, in which said resiliently deformable member is arranged between the limb and the second abutment.

6. A clamp according to claim 2, 3, 4 or 5, in which the position of the second handle is adjustable relatively to the cantilever arm.

7. A clamp according to claim 6, in which the handle is on a screw carrying a nut to which the cantilever arm is connected.

8. A clamp according to any preceding claim, in which the second handle moves towards the first handle in said relative movement in said first sense.

9. A clamp according to any preceding claim, in which the assembly comprises a sleeve through which the column extends and which carries the remainder of the assembly.

10. A clamp according to any preceding claim, in which the assembly includes a cam operable by a lever to force a lock-plate against the column to lock the assembly in position.

11. A clamp according to claim 4, or according to any preceding claim dependent on claim 4, in which one of said elements is on the cantilever arm and the other is on an additional arm carried by the limb adjacent the cantilever arm.

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

Claims (1)

1. Amendments to the claims have been filed, and have the following effect: Claims 1 above have been deleted or textually amended.

   New or textually amended claims have been filed as follows:

   1. A clamp for holding together a component and a pipe to which the component is to be joined comprising a column having a first handle at its first end and at its second end a first abutment laterally offset from the column and engageable with a first side of a pipe, and an assembly which includes a carrier, a second handle towards said first end of the column and a second abutment towards said second end thereof and laterally offset therefrom, said second handle and second abutment being carried by the carrier and the assembly being advanceable along the column to a position in which a component supported by the second abutment engages a second side of the pipe opposite to the first side, and in which position the carrier can be releasably locked to said column, relative movement of the handles in a first sense while the carrier remains locked in said position stressing a resiliently deformable member the load in which is applied to the second abutment to force the component against the pipe, the assembly also including means to hold the member stressed after the handles have been released and an index element and a scale element relatively movable to indicate the load applied to the component.