Method for manufacturing plastics blanks

Claim 1

In a method of forming plastic blanks, the steps of: 1. accumulating flowable plastic material in a chamber defined by a fixed accumulator and an end portion of an outer movable mold, said outer mold including a cavity in which a movable cylindrical core pin is concentrically positioned to define a mold cavity for forming plastic blanks, and said outer mold including a passageway extending from the end thereof to said cavity; 2. during Step (1), (A) closing the mold passageway with a retractable shaft which extends through the accumulator chamber and (B) axially confining a pair of radially movable neck rings between the outer mold and an axially displaceable end plate; 3. thereafter, displacing the shaft from the closing position to a retracted position to establish fluid communication between the accumulator chamber and the mold cavity; 4. relatively moving the accumulator with respect to the outer mold, the core pin, the neck rings, and the end plate to move the mold end portion into the accumulator chamber to force plastic material through the passageway into the mold cavity; 5. during Step (4), (A) relatively moving the retractable shaft and the mold passageway toward each other, (B) retracting a tubular sleeve from within the mold cavity against a biasing force in response to the flow of plastic material into the cavity, (C) withdrawing the sleeve through the neck rings to expose a neck ring cavity, and (D) axially confining the neck rings between the outer mold and the end plate;