Plastic expulsion process
OwnerTerrence C. Pearsoninventor
Life of this patent
Estimating the term…
Abstract
A system and process for gas assisted plastic injection molding. The plastic material is injected into the mold cavity and the molding pressure is held for a period of time. Thereafter, gas is injected into the plastic material and the pressure is again held for a period of time. Thereafter, valve members are opened allowing plastic to be expelled into one or more secondary cavities, or to be expelled back into the machine barrel.
Claims26
A process for injection molding a hollow plastic article comprising the steps of:
- (a) injecting a quantity of plastic material into a mold cavity to substantially fill the mold cavity;
- (b) applying a packing pressure to the plastic in the mold cavity;
- (c) injecting pressurized gas into the plastic material in the mold cavity in order to combine the application of packing pressure to the plastic;
- (d) holding the pressure of the gas and plastic in the mold cavity for a predetermined amount of time;
- and
- (e) allowing a portion of the plastic material in the mold to be expelled into at least one secondary cavity coupled to the mold cavity by opening a valve in a runner connecting the mold cavity to the secondary cavity.
A process for injection molding a hollow plastic article comprising the steps of:
- (a) injecting a quantity of plastic material into a mold cavity to substantially fill the mold cavity;
- (b) applying a packing pressure to the plastic in the mold cavity;
- (c) injecting pressurized gas into the plastic material in the mold cavity;
- (d) holding the pressure of the gas and plastic in the mold cavity for a predetermined amount of time;
- (e) allowing a portion of the plastic material in the mold to be expelled into at least one secondary cavity coupled to the mold cavity;
- (f) permitting the plastic material to solidify;
- (g) exhausting the gas from the mold cavity;
- and
- (h) removing the plastic article from the mold.
A process for injection molding a hollow plastic article utilizing an injection molding machine with a barrel and nozzle and a mold with a mold cavity therein having a shape defining at least a portion of the article, said method comprising the steps of:
- (a) injecting a quantity of plastic material into the mold cavity from the injection molding machine;
- (b) injecting pressurized gas into the plastic material in the mold cavity;
- and
- (c) allowing a first portion of the plastic material in the mold to be expelled back into the barrel of the injection molding machine.
Dependencies are inferred from the claim text.