Extrusion die for thermoplastic pipe - has electrically heated mandrel with gapped supply transformer for feeding reinforcement through gap

摘要

A forming head, for making reinforced thermoplastic pipes or hoses by extrusion, comprises a mandrel onto which the reinforcement is fed axially. The mandrel forms the inner member off an annular extrusion die. The mandrel has an electric heater. Current to this heater is supplied through a transformer having a prim. winding carrierd from a frame and a sec. winding carried by the mandrel. The reinforcement is fed through a gap between the two windings. The mandrel can be kept continuously at a desired temp. Output is increased 2.5-3 times compared with previous appts. Quality is also improved.