Apparatus for producing injection molded and centrally apertured disc records

An injection molding apparatus for molding centrally apertured parts, said apparatus comprising:

• A. an injection nozzle;
• B. a platen secured to a frame;
• C. a sprue bushing secured to said platen;
• said sprue bushing having an opening in communication with said injection nozzle;
• D. a first mold-half;
• E. bearing means for supporting reciprocal motion of said first mold half relative to said platen;
• F. a second mold-half;
• G. bearing means for supporting reciprocal motion of said second mold-half relative to said platen;
• H. a punch;
• I. bearing means for supporting reciprocal motion of said punch relative to said second mold-half;
• J. selectively actuated means for causing motion of said second mold-half between a closed location and an open location;
• said punch having an end portion in registry with said sprue bushing;
• said punch end portion defining with said opening in said sprue bushing a sprue passage, and said first and second mold halves defining an annular cavity surrounding said sprue passage, when said second half-mold is in said closed location;
• and said annular cavity and said sprue passage forming, respectively, said centrally apertured part and a sprue when heated material is injected therein;
• K. selectively actuated means for causing motion of said first mold-half with said second mold-half in response to motion of said second mold-half from said closed location to a location which is intermediate of said closed location and said open location whereby said annular cavity remains closed while said first and second mold halves move from said closed location to said intermediate location;
• and
• L. selectively actuated means for locking said punch in place while said first and second mold halves move from said closed location to said intermediate location whereby said sprue is severed from said part along the peripheral surface of said punch end portion;
• and a portion of said first mold-half where said punch end portion enters serving as a die.