US 7,754,134 B2 · Injection molding process

Abstract

The present invention relates to an injection molding process that improves recovery limited productivity. The present invention advantageously applies pressurized fluid within the nozzle of an injection molding machine to improve the machine's productivity. In accordance with one aspect of the invention, an existing or new injection molding machine is outfitted with a pressurized fluid system at the nozzle between the plasticizer barrel and the melt manifold. The use of a specialized nozzle and isolation valve allows the pressurized fluid to displace material within the nozzle and runner, ensuring the proper pressure is applied to the plastic resin within the mold during pack and hold while the plasticizing screw can begin its recovery cycle. Finally, the pressurized fluid can be evacuated from the nozzle melt stream area either via the fluid entrance or a fluid pin.

Claims13

Dependent claims

An injection molding process used to create a molded piece which comprises:

injecting a first volume of heated resin from an injection unit through a nozzle assembly into a mold cavity;
filling said mold cavity with said first volume of heated resin;
injecting a volume of fluid into said nozzle assembly following said first volume of heated resin;
isolating said injection unit from said first volume of heated resin within said mold cavity;
utilizing said fluid within said nozzle assembly to provide pressure on said first volume of resin in said mold cavity for a period of time while said first volume of resin hardens into said molded piece, wherein said fluid pressure provided remains in said nozzle assembly and does not enter said mold cavity;
preparing a second volume of heated resin within said injection unit during said period of time while said first volume of heated resin hardens into said molded piece within said mold cavity;
and
ejecting said molded piece from said mold cavity following said period of time.

5 more elements

Dependencies are inferred from the claim text.

Injection molding process

Life of this patent

Injection molding process

Life of this patent

Abstract

Claims13