Method for extruding cellular thermoplastic products
US3972970A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Feb 7, 1974 |
| Grant date | Aug 3, 1976 |
| Priority date | — |
| Expiry date | Feb 7, 1994 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB29L2031/3462
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
A product comprising a cellular plastic material is extruded from a modified conventional extrusion head by injecting a gaseous expanding medium into advancing fluent plastic material through porous material forming at least a portion of a section of the core tube in an extrusion chamber. By controlling the interrelationship between various process parameters such as the speed and pressure of the advancing fluent plastic material, the rate of injection of expanding medium into the advancing plastic material, the place where the expanding medium is injected, and the amount the extruded product is allowed to expand before cooling, it is possible to extrude, from a single source of fluent plastic material, a product comprising many different configurations of cellular and solid plastic material such as a uniform cellular structure throughout, or a cellular plastic inner section with a more dense outer covering.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.