Extrusion machine for tubular thermoplastic premoldings comprises head with coaxial flow channels connected to conical section which widens towards its base and connects with cylindrical section, in which piston moves up and down

摘要

Extrusion machine for producing tubular coextruded thermoplastic premoldings comprises an extrusion head (10) with coaxial flow channels (FK1, FK2). Each of these is fed with melt through a single inlet (ZF1, ZF2) and this flows over a distribution ring (26, 28) and down a frustro-conical ring. It then enters a conical section (12) which widens towards the base of the head and flows from this into a cylindrical section (14), in which a piston (16) can move up and down. Finally it flows out through a closable gap (20) at the base of an annular channel (18).