Patent ID: 8561428

Claim:
A method of operating a plunger in a blank mold to mold a parison from a glass gob, the plunger being driven by a piston in a cylinder to which a source of a pressurized medium may be applied at selected pressures, the method comprising: monitoring the position of the plunger in the blank mold versus time during at least one parison forming cycle beginning at a time t 1 and ending at a time t 4 ; detecting a first characteristic of the movement of the plunger at a time t 2 during the at least one monitored parison forming cycle; detecting a second characteristic of the movement of the plunger at a time t 3 during the at least one monitored parison forming cycle; and based on time t 2 , determining a time t p2 before t 2 ; based on time t 3 , determining a time t p3 before t 3 ; and during a parison forming cycle subsequent to the at least one monitored parison forming cycle, after a gob is loaded into the blank mold, applying a first pressure from time t 1 to time t p2 , a second pressure from time t p2 to time t p3 , and a third pressure from time t p3 to time t 4 .