초록 ▼

A method of injection molding for use with an injection molding machine includes: (a) generating pressurized gas and pressurized moisture within molten plastic as plastic pellets are plasticized in the injection molding machine, the pressurized gas and the pressurized moisture having a total pressur

A method of injection molding for use with an injection molding machine includes: (a) generating pressurized gas and pressurized moisture within molten plastic as plastic pellets are plasticized in the injection molding machine, the pressurized gas and the pressurized moisture having a total pressure defining an internal counterpressure within the molten plastic; (b) pressuring air within a cavity of a mold in the injection molding machine to an air pressure level which is substantially equal to the internal counterpressure in order to counterbalance the internal counterpressure as the molten plastic is injected into the cavity, thus providing a substantially pressure balanced molding environment for the plastic; and (c) maintaining the air pressure level in the cavity substantially constant as the molten plastic is injected into the cavity. A mold apparatus for use with the method of injection molding includes selectively sealed venting of the mold cavity, the vents being configured to maintain a substantially constant air pressure within the cavity as the cavity is filled with molten plastic.

대표청구항 ▼

A method of manufacturing a mold for use with an injection molding machine, the mold including first and second halves with a mold cavity formed therebetween, the method comprising: providing a plurality of vents in one of said halves, said vents having first and second ends, said first end being in

A method of manufacturing a mold for use with an injection molding machine, the mold including first and second halves with a mold cavity formed therebetween, the method comprising: providing a plurality of vents in one of said halves, said vents having first and second ends, said first end being in fluid flow communication with said cavity, said vents being sufficiently sized to maintain a substantially constant air pressure in said cavity as said cavity is being filled with plastic; providing a channel in one of said halves in fluid flow communication with said second end of each of said plurality of vents; providing at least one valve in selective fluid flow communication with said channel to selectively receive pressurized air therethrough into the channel and to selectively allow discharge of pressurized air from the channel; and providing a seal circumscribing said cavity and said channel, and positioned between said first and second halves to selectively prevent unwanted discharge of pressurized air from the cavity and the channel as molten plastic is injected into the cavity from the injection molding machine.