Patent ID: 8033808

Claim:
An apparatus for molding, said apparatus comprising: a die sheet having a first surface defining a mold cavity and a second surface opposite said first surface, said die sheet configured and dimensioned to mate to a mating mold section; a die support having a rim that contacts a portion of said second surface of said die sheet, said rim forming a seal with said die sheet, said second surface and said die support defining a fluid cavity, said fluid cavity having an inlet and an outlet, said fluid cavity configured to receive a fluid in said inlet and discharge said fluid in said outlet, said fluid being a liquid; a first pressure sensor measuring a mold pressure of said mold cavity; a second pressure sensor measuring a cavity pressure of said fluid cavity; a pair of isolation valves each in fluid communication with one of said inlet and outlet; a pressure generator in fluid communication with said fluid cavity, said pressure generator configured to pressurize said fluid cavity when said pair of isolation valves are closed; and a controller monitoring said first and second pressure sensors, said controller operatively connected to said pair of isolation valves, said controller configured to operate said pressure generator to maintain said cavity pressure substantially the same as said mold pressure when said pair of isolation valves are closed, said controller executing a process including (a) circulating said liquid at a first temperature through said fluid cavity with said pair of isolation valves open and before injecting a molding material into said mold cavity and with said liquid flowing through said pair of isolation valves, (b) circulating said liquid at a second temperature through said fluid cavity with said pair of isolation valves open and while injecting said molding material, (c) closing said pair of isolation valves, (d) controlling said cavity pressure to be substantially the same as said mold pressure until said mold pressure falls below a specified value, and (e) opening said pair of isolation valves and circulating said liquid at a third temperature through said fluid cavity.