Extrusion process for producing thermoplastic pipe
US4512943A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 20, 1983 |
| Grant date | Apr 23, 1985 |
| Priority date | — |
| Expiry date | May 20, 2003 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S264/46
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
A process is disclosed for the formation of pipe comprising one or more layers of thermoplastic resin whereby an annular stream of thermoplastic material is transported through an annular extrusion passageway. The downstream annular portion of the extrusion passageway has a radially movable outer wall. The outer wall is radially moved by heat expansion of a bolt thereagainst to change the thickness of a particular arcuate section of the stream. The thickness of the particular arcuate section of the stream may be further changed through selectively heating by electrical resistive elements an arcuate section of the extrusion passageway to heat the stream of thermoplastic material transported in proximity thereto.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.