Plastic injection molding with reduced dimensional variations using gas pressure and secondary plastic injection
US6468465B1 · kind B1 · utility
Assignee
Inventor
Key dates
| Filing date | Apr 17, 2000 |
| Grant date | Oct 22, 2002 |
| Priority date | — |
| Expiry date | Apr 17, 2020 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T74/19
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
In a method of plastic injection molding of plastic parts with a critical external dimensional accuracy, in particular plastic gears, the plastic molding material is first injected into the mold, and then gas is injected under pressure into the mold to reduce shrinkage of the plastic material away from the mold surface, forming a gas bubble in the plastic molding material in the mold. Then after cooling of that first injected plastic, a separate, secondary injection of more of the same plastic material under pressure into the gas bubble, in the mold (before removing the plastic part from the mold), provides increased strength and a uniform rotational moment of inertia of the gear.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.