Patent EA-001743-B1 (EA)
Title: Method and arrangement for manufacturing of electrically heat-weldable plastic tube fittings
Inventor: ALKIO JOUNI ALEKSI
IPC: B29C45/26
Filed: 1998-09-04
Abstract: 1. A method for manufacturing of electrically heat-weldable plastic tube fittings in an injection mould, whereby - 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, characterized in that - a guide bushing (11, 12) is disposed in connection 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 process is started by introducing moulding compound around the core (1) in the moulding space (3) in a manner knownper 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the holding power of the actuator, such as a spring (15, 16), and that - after the injection moulding, the core (1) is withdrawn from the mantle (2), the mantle (2) including the guide bushing (11, 12) is opened, and the finished fitting is removed from the injection mould. 2. A method as claimed in claim 1, characterized in that the recess (7, 8) in each pin (9, 10) is disposed to extend through the core (1). 3. A method as claimed in claim 1 or 2, characterized in that the pin (9, 10) and the guide bushing (11, 12) are disposed to rise under the plastic pressure to the desired level above the core (1). 4. A method as claimed in claim 1, 2 or 3, characterized in that the resistance wire (4) is wound into contact with the peg (5, 6). 5. An arrangement for manufacturing electrically heat-weldable plastic tube fittings in an injection mould, comprising the core (1) and the mantle (2) of the injection mould and a moulding space (3) provided between these, the electrically heated resistance wire (4) being wound about the core (1), the arrangement comprising: - pegs (5, 6), the ends of the resistance wire (4) being attached in connection with these,  - recesses (7, 8) provided in the core (1), - pins (9, 10) for supporting the pegs (5, 6), the pins being fitted in the recesses (7, 8), characterized in that the arrangement further comprises - guide bushings (11, 12), which are disposed to support the pins (9, 10), - a recess (13, 14) in the mantle (2) for each guide bushing (11, 12), the guide bushings (11, 12) being supported through the recesses (13, 14) on the mantle (2) of the injection mould, and - an elastic actuator, such as a spring (15, 16) in each recess (13, 14) behind the guide bushing (11, 12), the actuators (15, 16) serving to retain the guide bushings (11, 12) and with these the pins (9, 10) in position, the pins (9, 10) and further the guide bushings (11, 12) being disposed to rise from the recesses (7, 8) under the action of the plastic pressure against the holding power of the actuator (15, 16) during the injection moulding step. 6. An arrangement as claimed in claim 5, characterized in that the recess (7, 8) in each pin (9, 10) is disposed to extend through the core (1). 7. An arrangement as claimed in claim 5 or 6, characterized in that each pin (9,10) and guide bushing (11, 12) is disposed to rise under the plastic pressure to the desired level above the core (1), a stopper (17, 18) having been positioned at this point.