Sequential co-injection unit adapted for structural foam molding
US4124308A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jun 21, 1977 |
| Grant date | Nov 7, 1978 |
| Priority date | — |
| Expiry date | Jun 21, 1997 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S264/83
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
A single screw injection device or extruder sequentially injects skin and foamed plastics melts into a mold to produce structural skin covered foam molded parts free from swirl marks. A single extrusion screw or plasticator selectively feeds, compresses and meters a plastics melt to a first injector for skin melt injection or to a gas injection well where it meters gas flow into the melt, mixes the gas and melt to form a foam and feeds the foam to a second injector for foam melt injection into the mold. A valve controls the flow of the plastics melt and the foamed plastics melt to a single injection nozzle for discharge into the mold. In sandwich molding, a small amount of the unfoamed melt is first injected to form the skin for the molded article and then the valve is shifted to connect the nozzle with the foamed melt from the screw whereupon the injector forces the foamed melt through the nozzle into the mold to overlie the skin melt. The skin melt and the foamed melt are fed through the same nozzle and swirling in the mold is avoided.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.