Pipe extrusion apparatus including winding a hollow profile

Apparatus for producing a helical seam profile pipe from thermoplastic tube having a generally rectangular cross section, the apparatus comprising:

• a frame;
• a mandrel mounted on the frame for rotation on the frame about a longitudinal axis of the mandrel to helically wind the thermoplastic tube around the mandrel forming adjacent turns of the tube on the mandrel;
• a source of filler material;
• and
• a filler material applicator located adjacent to the mandrel and just upstream from a location where the thermoplastic tube first contacts the mandrel as it is wound onto the mandrel, the applicator being adapted to continuously apply a bead of the filler material to the thermoplastic tube prior to being wound on the mandrel, each new turn of the thermoplastic pipe being brought into engagement with the preceding turn such that the applied filler material is brought into contact with a wall of the thermoplastic tube in the preceding turn for joining the new turn to the preceding turn, the filler material applicator having an outlet side positioned for facing toward the thermoplastic tube and other sides, and an outlet on said outlet side for dispensing the filler material along only one lateral wall of the thermoplastic tube prior to being wound on the mandrel, said other sides of the applicator being free of any outlets whereby said one lateral wall is the only lateral wall to which filler material is applied, the applicator being arranged so that an applied bead of filler material extends longitudinally on said lateral wall of the tube being wound on the mandrel, with no filler material directly applied from the applicator to the tube of the preceding turn, the apparatus being free of any other filler material applicators located downstream of said filler material applicator.

Apparatus for forming thermoplastic tube having a generally rectangular cross section and winding the tube to make a helical seam profile wall pipe, the apparatus comprising:

• a first extruder for extruding molten thermoplastic material;
• a die for receiving the extruded material from the first extruder for forming the thermoplastic tube, the die being configured to form the molten thermoplastic material into a generally rectangular cross-section having non-uniform wall thickness wherein the thickness tapers on an inside surface of the tube, with greater thickness at a corner region of the cross-section than at a mid-wall location;
• at least one cooling device for cooling the tube exiting the die;
• a frame;
• a mandrel mounted on the frame for rotation on the frame about a longitudinal axis of the mandrel to helically wind the thermoplastic tube around the mandrel forming adjacent turns of the tube on the mandrel;
• a second extruder for extruding filler material;
• a filler material applicator located adjacent to the mandrel and adapted to receive filler material from the second extruder for continuously applying a bead of the filler material to the thermoplastic tube prior to being wound on the mandrel, each new turn of the thermoplastic pipe being brought into engagement with the preceding turn such that the applied filler material is brought into contact with a wall of the thermoplastic tube in the preceding turn for joining the new turn to the preceding turn.