Patent ID: 7118371

Claim:
Apparatus for introducing a moldable thermoplastic material into an annular mold cavity to mold an annular thermoplastic part that has no more than a single weld line therein, said apparatus comprising: an annular mold cavity having an annular opening thereinto; a fixed pin axially aligned with the opening of the mold cavity and being immovable during molding relative to the opening of the mold cavity; a passage extending through said fixed pin for venting air from said mold cavity; an annular sleeve surrounding the fixed pin and being moveable with respect to the fixed pin between a first position that is adjacent to the mold cavity and a second position that is away from the mold cavity to define, with the fixed pin when in the second position, an annular path for introducing moldable thermoplastic material into the annular opening of the mold cavity; and means for introducing moldable thermoplastic material into the annular path, at a location upstream of the second position of the annular sleeve, in no more than a single path.