초록 ▼

A supply of pressurized gas is separated into a first quantity of pressurized gas at a first temperature and a second quantity of pressurized gas at a second lower temperature. The first and second quantities of gas are injected into molten plastic in an injection mold in a predetermined sequence to

A supply of pressurized gas is separated into a first quantity of pressurized gas at a first temperature and a second quantity of pressurized gas at a second lower temperature. The first and second quantities of gas are injected into molten plastic in an injection mold in a predetermined sequence to form a hollow molded plastic article. A controller independently controls the pressure and time of delivery of the first and second quantities of pressurized gas supplied to the mold. A third quantity of extremely lower temperature gas may also be supplied to the mold in a timed sequence with the first and second quantities of gas. A variable pressure regulator receives stored pressure signals from the controller and establishes the pressures of the first, second and the optional third quantities of gas independent of each other.

대표청구항 ▼

[ What is claimed is:] [1.] A gas assisted injection molding apparatus for use with an injection mold, the apparatus comprising:means for injecting molten plastic into an injection mold;a source of injection gas;first means, disposed in fluid communication with the source of injection gas, for deliv

[ What is claimed is:] [1.] A gas assisted injection molding apparatus for use with an injection mold, the apparatus comprising:means for injecting molten plastic into an injection mold;a source of injection gas;first means, disposed in fluid communication with the source of injection gas, for delivering a first quantity of injection gas at a first temperature to the injection mold;second means, disposed in fluid communication with the source of injection gas, for delivering a second quantity of gas at a second temperature to the injection mold;means, communicating with the first delivering means, for making the first temperature of the first quantity of gas higher relative to the second temperature of the second quantity of injection gas,first valve means and second valve means, disposed in fluid communication with the first means for delivering the first quantity of injection gas and the second means for delivering the second quantity of injection gas, respectively, for causing flow of the first and second quantities of injection gas into the injection mold to force the molten plastic against the mold to form a hollow interior within the plastic as the molten plastic solidifies;control means for controlling the first and second valve means to cause flow of the first and second quantities of injection gas into the injection mold in a preset sequence, the control means generating control signals representative of a separate, variably selected pressure for each of the first and second quantities of injection gas during each injection molding cycle; anda single variable pressure regulator connected in fluid flow communication with the first and second valve means and responsive to control signals from the control means for selectively setting a separate pressure for the delivery of each of the first and second quantities of injection gas to the injection mold.