GB2215804A - Pipelines - Google Patents

Abstract

A device (10) for applying a longitudinal force to an elongate cylindrical workpiece, includes a jaw assembly (16) reciprocable longitudinally of the workpiece and at least three jaws (17, 18, 19) of which at least two are mutually pivotably towards each other and into gripping relationship with the workpiece. <IMAGE>

Description

PIPELINES This invention relates to a device for applying a longitudinal force to an elongate cylindrical workpiece.

A device of the above type may be used as a means for pushing a lining tube into a length of pipe to be lined in the course of a pipe-lining method such as is described in UK published patent application No. 2186340A.

It is an object of the invention to provide an improves device for such pipe-lining.

The invention provides a device, for applying a longitudinal force to an elongated cylindrical workpiece, comprising a jaw assembly reciprocable longitudinally of the workpiece, the assembly including at least three jaws each in the form of a segment of cylinder, at least two of the jaws being mounted for respective pivotal movement into gripping relationship with the workpiece.

The invention will be described further by way of example, with reference to the accompanying drawings, wherein : Fig. 1 is a perspective view of a device forming part of tube heating and compressing apparatus for use in pipe lining, Fig. 2 is a perspective view of the device shown in Fig. 1; and Fig. 3 is an end elevation of the device.

A preferred device 10 of the invention is part of or attached to a tube heater/compressor apparatus 11 of the type described in 2186340A, this apparatus having a heater and a compressing die (neither visible) within a casing 12. A tube 13 (as shown in dot-dash lines) to form a pipe lining passes through the apparatus 11 and to pusher 10. Pusher 10 is co-axial with apparatus 11 and has a carriage 14 which can be reciprocated by a pair of synchronised rams 15.

Mounted on carriage 14 is a gripper assembly 16 which includes a fixed lower jaw 17 and two movable jaws 18,19. In use, with the carriage 14 adjacent the apparatus 11, the jaws 17,18,19 grip the tube tightly, the carriage moves away from the apparatus 11 drawing the tube through it and "pushing" it towards the pipe.

When the carriage reaches the end of its travel it releases the tube and repeats the operation. Each jaw 18,19 is extended over just less than 120 degree arc of a circle. Jaw 17 is fixed to carriage 14 and movable jaws 18,19 are mounted on respective arms 20,21 which are pivoted at 22,23 respectively and, cross above the jaw opening 24 and have extensions 25,26 between which is disposed a hydraulic ram 27.

In use, ram 27 urges extensions 25,26 apart, and arms 20,21 urge the movable jaws 18,19 to pivot inwardly about pivots 22,23.

This arrangement of jaws gives a very powerful grip on the tube 13, enabling a longitudinal tension to be applied to the tube which is significantly higher than can be achieved with a conventional "pusher". This enables cable -tensions to be redllcec even with a very tight fit between pipe and tube, thus reducinc the risk of lash injuries to personnel.

The invention is not limited to the details of the foregoing and variations can be made thereto. For example, as indicated in dotted lines at 28 in Fig. 3, liners can be releasably attached to jaws 17,18,19 to enable the pusher to operate with tubes o smaller diameter. The jaws can be reciprocable by a mechanism other than that described, for example by a powered lazy tongs arrangement, or by a parallelogram linkage. There can be any convenient number of jaws e.g. more than three. A set of four jaws could be provided arranged in two pairs, each pair being mounted by a linked arm arrangement of the sort which mounts jaws 18,19 above.

The device of the invention can be used for applying a longitudinal force to any cylindrical article, for example to grip and transfer a cylindrical workpiece to or from a machine.

Many additional variations are possible within the scope of the following claims.

Claims (9)

1. A device, for applying a longitudinal force to an elongate cylindrical workpiece, comprising a jaw assembly reciprocable longitudinally of the workpiece, the assembly including at least three jaws each in the form of a segment of cylinder, at least two of the jaws being mounted for respective pivotal movement into gripping relationship with the workpiece.

2. A device as claimed in claim 1 wherein the jaws are generally equal in circumferential extent.

3. A device as claimed in claim 1 or 2 wherein there are three jaws of which one is laterally fixed and the other two are pivoted about axes parallel to the device axis and alongside the one jaw.

4. A device as claimed in claim 3 wherein each pivotable jaw is mounted on an arm whose one end is connected to the pivot whose centre wraps around its respective jaw and whose end has an outwardly extending extension, the two arms crossing and a fluid cylinder between the extensions urging them apart and the arms together.

5. A device as claimed in claim 1 or 2 and wherein there are four jaws arranged in two pairs, each pair being pivotally mounted for mutual movement towards each other and a workpiece.

6. A device as claimed in any of claims 1 to 5, wherein the jaw assembly is mounted upon a carriage for movement longitudinally of a workpiece.

7. A device as claimed in any of claims 1 to 5 and mounted on a lazy tongs arrangement for movement longitudinally oi a workpiece.

8. A device as claimed in any preceding claim and attached to a front end of a tube heating and compressing apparatus.

9. A device for applying a longitudinal force to an elol-ga~ cylindrical workpiece substantially as hereinbefore described with reference to the accompanying drawings.