Process and apparatus for direct gating injection molding

An apparatus for injection molding a hollow plastic article having at least two sidewalls, said apparatus comprising:

• an injection molding machine having a first mold portion defining a female cavity portion and a second mold portion defining a male core portion which is shiftable relative to said cavity portion, said mold portions being movable between a mold open position and a mold closed position;
• said mold core portion being substantially centered within said mold cavity portion when said portions are in said mold closed position and defining with said mold cavity portion a space in the shape of said article;
• said space having a sidewall defining portion and a circumferentially extending region of greater thickness located at an approximate center point of said sidewall defining portions;
• and
• means for introducing molten plastic material into said space in the vicinity of said circumferentially extending region without creating any significant side load which would cause said male core portion to shift relative to said female cavity portion,
• whereby said mold core portion remains substantially centered within said mold cavity portion.