Patent ID: 6907756

Claim:
A plunger for being attached to a piston that inserts and withdraws the plunger from the neck region of a blank mold during the manufacture of a parison for forming glass containers in the blow-and-blow process comprises: a hollow cylindrical body, the lower end of which defines means for attaching the plunger to the piston; a radial flange extending from the exterior of the cylindrical body; a nose portion attached to the upper end of the hollow cylindrical body configured for insertion in the neck region of the blank mold, there being a shoulder defined between the nose portion and the hollow cylindrical body; one or more passages extending between the interior of the hollow cylindrical body and the shoulder; the nose portion having a hollow interior opening at the upper end thereof; one or more passages extending between the interior of the hollow cylindrical body and the hollow interior of the nose portion; a guide bore extending between the interior of the hollow cylindrical body and the hollow interior of the nose portion; a valve having a stem and a valve stopper, said valve stem positioned within said bore such that in its most downward position the valve stopper closes the hollow interior opening; a temperature resistant spring coiled around the valve stem for urging the stopper away from the valve seat; and means for restraining the maximum upward movement of the valve stem.