Apparatus for molding hollow workpieces

A drive system for an injection molding apparatus, said drive system having a longitudinal axis defining an axial direction and comprising:

• a stripper plate mounted for bilateral reciprocating motion, said stripper plate having a first face and a second face opposed thereto;
• a core pin protruding outwardly and forwardly through a hole in said stripper plate, said core pin being usable to form a cavity in a molded workpiece;
• a core pin sleeve circumscribing said core pin and being juxtaposed with said first face of said stripper plate, said core pin sleeve having a feature to form an undercut in a molded workpiece removably disposed on said core pin;
• a hollow stripper sleeve, said hollow stripper sleeve being rigidly joined to said second face of said stripper plate, said hollow stripper sleeve being concentric with said core pin and circumscribing said longitudinal axis, said hollow stripper sleeve having at least one stripper sleeve cam therein, said stripper sleeve cam providing for responsive motion of a respective stripper sleeve follower when said stripper plate is moved in the axial direction;
• a core pin base rigidly joined to said core pin, said core pin base having at least one core pin base cam therein, said core pin base cam providing for responsive motion of a respective core pin base follower when said stripper plate is moved in the axial direction;
• a stripper sleeve insert intermediate sad hollow stripper sleeve and said core pin base;
• said stripper sleeve insert having an outwardly extending stripper sleeve follower cooperating with said stripper sleeve cam and an inwardly extending core pin base follower cooperating with said core pin base cam, said stripper sleeve insert being rigidly joined to said core pin sleeve,
• whereby axial movement of said stripper plate causes motion of said hollow stripper sleeve and said core pin base to be superimposed onto said stripper sleeve insert to cause responsive axial and/or rotational motion in said core pin sleeve;
• and
• wherein said core pin does not translate or rotate relative to said stripper plate.

An injection molding apparatus having a drive system reciprocating along a longitudinal axis in an axial direction, said injection molding apparatus comprising:

• a first mold half and a second mold half which open and close in the axial direction, said first mold half and said second mold half defining a cavity for molding a workpiece therein;
• one of said mold halves comprising a stripper plate drivable in the axial direction, said stripper plate having a first face and a second face opposed thereto;
• a core pin protruding outwardly through a hole in said stripper plate, said core pin being usable to form the cavity in a molded workpiece;
• a core pin sleeve circumscribing said core pin and being juxtaposed with said first face of said stripper plate, said core pin sleeve having a feature to form an undercut in a molded workpiece removably disposed on said core pin;
• a hollow stripper sleeve, said hollow stripper sleeve being rigidly joined to said second face of said stripper plate, said hollow stripper sleeve being concentric with said core pin and circumscribing said longitudinal axis, said hollow stripper sleeve having at least one stripper sleeve cam therein, said stripper sleeve cam providing for responsive motion of a stripper sleeve follower when said stripper plate is moved in the axial direction;
• a core pin base rigidly joined to said core pin, said core pin base having at least one core pin base cam therein, said core pin base cam providing for responsive motion of a core pin base follower when said stripper plate is moved in the axial direction;
• a stripper sleeve insert intermediate said hollow stripper sleeve and said core pin base;
• said stripper sleeve insert having the outwardly extending stripper sleeve follower cooperating with said stripper sleeve cam and the inwardly extending core pin base follower cooperating with said core pin base cam, said stripper sleeve insert being rigidly joined to said core pin sleeve,
• whereby axial moment of said stripper plate causes motion of said hollow stripper sleeve and said core pin base to be superimposed onto said stripper see insert to cause responsive axial and/or rotational motion in said core pin sleeve to remove a workpiece from and molded on said core pin;
• and
• wherein said core pin does not translate or rotate relative to said stripper plate.