Co-extrusion apparatus and method for producing multiple-layered thermoplastic pipe
US4249875A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 15, 1978 |
| Grant date | Feb 10, 1981 |
| Priority date | — |
| Expiry date | Sep 15, 1998 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB32B27/08
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
A melt extrusion process and apparatus for producing a multiple-layered pipe (preferably of two or more thermoplastic resins) are disclosed. The process comprises extruding a cylindrical stream of thermoplastic material, converting the cylindrical stream to an annular stream, applying at least one inner annular layer of thermoplastic to the inner surface of the annular stream, applying at least one outer annular layer of thermoplastic material to the annular stream, and extruding the resultant multiple-layered annular stream. Apparatus for producing this pipe includes a modular pipe die having inside and outside laydown means, flow equalizing means within each of the inner and outer laydown means to obviate layer imperfections, and adjustable means to control the concentricity of the outer layers. The invention finds particular application in the production of a thermoplastic pipe having an intermediate expanded core.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.