Method and device for extrusion of a double wall plastics pipe
US4790975A · kind A · utility
15Cited by
13References
5Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Nov 12, 1986 |
| Grant date | Dec 13, 1988 |
| Priority date | — |
| Expiry date | Nov 12, 2006 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB29L2023/18
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
Method in extruding a double-walled plastic tube by using plastic materials of different colors for the inner layer and the outer layer, a portion of the material for the inner layer being diverted to form a longitudinal strip of the outer layer on the outside surface of the tube. The invention also relates to an extrusion tool for working the method, wherein an element (21) is provided inside the tool to divert material from a passage (19) for material for the inner layer to a passage (16) for material for the outer layer.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.