Method and arrangement to support counterslang heads for electrically heat-welded plastic tubing joints in spray-forming

摘要

The invention relates to a method and an arrangement for supporting the ends of a resistance wire in the manufacture of electrically heat-weldable plastic tube fittings in an injection mould. In the method, an electrically heated resistance wire (4) is wound about the core (1), the ends of the resistance wire (4) are connected to pegs (5, 6), pins (9, 10) are fitted into recesses (holes) (7, 8) provided in the core (1), and the pegs (5, 6) are supported on the core (1) by means of pins (9, 10) connected to them. In accordance with the invention, a guide bushing (11, 12) is disposed in contact with each pin (9, 10) and the connected peg (5, 6), each guide bushing (11, 12) is supported in a recess (13, 14) provided in the injection mould (2), an elastic actuator such as a spring (15, 16) is disposed to act on each guide bushing (11, 12) so that its holding power presses the guide bushing, the peg and the pin into position against the core (1), the injection moulding operation is started by introducing injection moulding compound around the core (1) in the moulding space (3) in a manner known per se, whereby, as the injection moulding compound reaches each pin (9, 10), the plastic pressure lifts the pin (9, 10), the peg (5, 6) and the guide bushing (11, 12) from the core (1) against the holding power of the actuator, such as a spring (15, 16), and after the injection moulding the core (1) is withdrawn from the mantle (2), the mantle (2) including the guide bushings (11, 12) is opened and the finished fitting is removed from the injection mould.