Fusion Group Plc

Roy Cartwright

Edwin A Dunkey

Patrick W Jenkins

The invention relates to the butt-welding of pipes of plastics materials. Equipment is alreaady known where pipe ends are first urged against a trimmer plate, and then urged against a heater plate to create beads of a required size at the ends of the pipes, following which the pipe ends are urged into abutting relationship for welding to occur. Particularly with automatic machines employing hydraulic power, the force applied between the pipe ends and the heater plate and subsequently between the pipe ends needs to include an allowance for the drag factor inherent in the pipeline and compensate for any frictional effect in the mechanical and hydraulic moving components, and which is a difficult calculation. The object of the invention is to overcome the difficulties mentioned above, which objective is met by means comprising two opposed clamping means in each of which is to be secured one end of a plastics pipe with the end of the pipe protruding beyond the respective clamp by a predetermined degree, said clamping means being movable towards and away from each other by the action of a suitable motive power, and there being linear movement sensing means to sense the degree of movement of the clamps and/or of pipes secured to the clamps towards each other, said sensing means having an output signal to arrest the application of motive power to the clamps when a predetermined degree of linear movement of the clamps and pipes towards each other has been completed.

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Dronfield, United Kingdom

Roy Cartwright