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United States Patent 4643665
Douris , ê et al. February 17, 1987

Check valve assembly for injection molding machine

Zeiger February 17, 1987

Abstract

An improved check valve assembly which is mounted on the front end of a feedscrew of an injection molding machine having a check ring which is slidably mounted on the shank of a retainer within the heated barrel of the molding machine. An annular-shaped flow gap is formed between the inner periphery of the check ring and retainer shank for feeding cylindrical-shaped sleeves of heated material into a discharge chamber at the forward end of the barrel. The check ring is movable between a forward material feed position where it is engaged with a front valve seat and a rearward material blocking position where it is engaged with a rear valve seat. An annular groove concentric with the annular-shaped material flow gap is formed in the front face of the front valve seat and has an average depth at least equal to the thickness of the sleeve of material moving through the flow gap to permit the sleeve of material to flow unrestricted from the gap and past the front valve seat and into a plurality of flutes for discharge into the discharge chamber.