Patent ID: 7140859
Filing Date: 2006-11-28
Classification: B29C,B29L,F16L,Y10T

Abstract:
1. An apparatus adapted to produce a monolithic, multi-walled tubular structure, wherein said structure comprises: at least one larger diameter outer tube; at least one smaller diameter inner tube, disposed substantially within the larger diameter outer tube, and a plurality of supporting rib struts disposed between said tubes and in supporting relationship to said tubes, wherein said smaller diameter inner tube, said larger diameter outer tube and said plurality of supporting struts are all collectively disposed in a configuration such that they all have circumferential and longitudinal vectors, wherein at least some of said struts are disposed in non-perpendicular relationship to the tubes that they support and are disposed in alternating positive and negative angles to tangents to said tubes such that two adjacent struts and the tubes that they intercept form triangular or trapezoidal truss cells; wherein said apparatus comprises: an extruder, comprising: at least two radially spaced apart arcuate extrusion dies, wherein said dies are adapted to extrude thermoplastic material into a molten, plastically deformable extrudate comprising: at least two radially spaced apart tubes; and a plurality of additional, substantially straight, extrusion dies disposed between said arcuate dies, wherein at least some of said additional extrusion dies communicate with both of said arcuate dies, wherein said additional dies are adapted to enable the extrusion of said supporting truss members disposed between and joined to said extruded tubes in the form of a monolithic extrudate structure; a puller adapted to assist in the movement of said monolithic extrudate structure in a downstream direction away from said extruder dies; a rotator adapted to rotate said molten, radially spaced apart inner and outer tubes and said plurality of truss members as a unit into a multi-wall tubular extrudate that has at least one longitudinal and at least one circumferential vector component to its shape; and a cooler adapted to cool said rotated extrudate to a solidified condition including freezing said monolith extrudate in a condition wherein substantially all of the elements of said frozen extrudate have a circumferential and a longitudinal component to their shape.