Patent ID: 7374412
Filing Date: 2008-05-20
Classification: B29C,B29K

Abstract:
1. An extrusion head for the production of a tubular multilayer preform of softened thermoplastic material with at least one viewing strip of translucent material extending in the extrusion direction, comprising an annular passage arrangement including a plurality of annular passages in mutually concentric relationship and forming mutually separate flow paths for material forming the various layers of the multilayer preform, at least two feed paths for feeding plastic material from at least one extruder to the annular passage arrangement, an annular gap nozzle having an annular gap communicating with the annular passage arrangement, and at least one flow passage radially opening into an annular passage of the annular passage arrangement for introducing material forming the viewing strip, the flow passage opening upstream of the annular gap in the region of separation of the flow paths, said flow passage being provided by a flow divider, the flow divider including a flow passage bore which extends transversely therethrough with respect to the extrusion direction and which establishes flow passage communication with said annular passage.