Patent ID: 8449799

Claim:
A method of in situ purging of a shutoff valve debris chamber of an injection molding apparatus comprising the steps of providing a chamber to be axially rearward of a manifold shutoff pin hole, the shutoff pin hole opening onto the chamber, a forward surface of a piston defining a rearward surface of the chamber; using an open gate supply port in fluid communication with the forward surface of the piston to displace the piston rearwardly to an open gate position; responsive to displacing the piston rearwardly to the open gate position, flowing polymer through a polymer melt flow bore coaxial with the shutoff pin, and through a gate into a mold; while performing said step of flowing the polymer, accumulating debris in the chamber resulting from polymer flowing from a polymer melt flow bore through the shutoff pin hole into the chamber; after said step of flowing the polymer, positioning the piston in a purging position; flowing a purging fluid from the open gate supply port into and through the chamber; and exhausting the purging fluid and debris out of the mold from an exhaust port in fluid communication with the chamber.