Method for blow molding a CVJ boot

A process for making a blow molded product in a mold which may be opened and closed comprising:

• a) extruding a tubular thermoplastic resin parison having first and second ends, said parison having a general axis of symmetry and said parison having a wall thickness at said first end;
• b) closing said mold about said parison;
• c) introducing spreading means into said first end of said parison and spreading said first end of said tubular parison to produce an enlarged opening at said first end;
• d) supporting said parison at least adjacent said first end in said mold so that resin of said parison may not expand radially;
• and then,
• e) introducing a core into said parison at said first end, said core having a portion with an outer surface adjacent said first end when said core is fully inserted which defines a clearance gap between said closed mold and said outer surface and said clearance gap is less than the wall thickness of said parison at said first end so that upon introduction of said core, a portion of thermoplastic resin comprising said parison is moved by said core in the direction of motion of said core and said core and said mold define a first end of said product;
• and then,
• f) introducing a pressurized gas into said parison to blow mold said product,
• and wherein said mold includes compression slides defining the molding surface of said mold adjacent said first end of said product and said compression slides are moved to the extended position before said core is introduced into said parison,
• and said portion of said thermoplastic resin is caused to flow in a direction which is generally radial to the axis of said parison, and
• said mold having additional compression slides adjacent said first end;
• said process including moving said additional compression slides from a retracted position to an extended position after said core has been introduced into said parison.