Method of injection molding
US5273707A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Nov 22, 1991 |
| Grant date | Dec 28, 1993 |
| Priority date | — |
| Expiry date | Nov 22, 2011 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB29C45/43
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
An injection mold apparatus has a core and cavity halves. One or more gas poppet valves are affixed in the injection mold either in the movable and/or in the stationary halves of the mold. The poppet valves (or poppets) are located to open into a mold portion formed in the cavity between the movable portion of the injection mold and the fixed mold portion when the mold portions are closed. At least one gas line is connected to the poppets and to a gas pressure source and is adapted to open the poppets to the passage of nitrogen or other gas into the mold following the injection of molten plastic into the closed mold halves. Porous metal covers may be used to cover the opening in the mold either the movable and/or stationary halves of the injection mold in lieu of the gas poppet valves, and the gas pressure through the porous metal cover can be used to carry out the molding operation. An injection molding method is also taught using the injection of nitrogen gas into the mold immediately following the injection of the liquid plastic.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.