Apparatus for gas assisted injection molding having precise control of injection and holding pressure with stepped holding pressure capability
US5295800A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 27, 1991 |
| Grant date | Mar 22, 1994 |
| Priority date | — |
| Expiry date | Nov 27, 2011 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S425/812
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
A method and apparatus for gas assisted injection molding which will first inject a shot of molten plastic into a suitable mold, shut off the plastic flow into the mold, and either immediately, or after a delayed time, inject a suitable pressurized gas into the mold at a desired injection pressure. The pressure of the gas in the mold is then controlled by stepping up or stepping down the pressure in the mold in a series of steps to arrive at a second predetermined and precisely controlled pressure. The predetermined pressure is held for a desired time. The setting and holding of pressure is repeated as many times as desired, and is then stepped down to a final pressure. The mold is then opened, and the article is removed.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.