Continuously producing flexible laminated insulating pipe - by feeding inner tube into multiple extrusion head for foam intermediate layer and outer tube

摘要

Appts. for prodn. of a flexible, laminated insulating pipe composed of a smooth inner pipe, a thermoplastics outer pipe and a layer of plastics foam insulation between the pipes, is claimed. Appts. comprises (a) first and second extruders for the thermoplastics material and insulating foam; (b) a co-extrusion head; (c) a pipe forming machine comprising a moving hollow mould in which the laminated pipe is finally formed; and (d) a pusher device for feeding in the smooth inner pipe (1). The co-extrusion head comprises a nozzle connected to the mould and used for extruding the outer pipe and an inner, concentric nozzle extending further into the mould and used for extruding the foam. The inner pipe enters to act as a core within the extruding nozzles and is supported by a concentric bore inside the foam extrusion nozzle; after leaving this bore it is held in position only by the foam itself. Appts. enables a laminated insulating pipe to be extruded continuously instead of in a series of lengths.