Process for producing plastic pipes having oval cross-sectional shape
US4165354A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Aug 15, 1977 |
| Grant date | Aug 21, 1979 |
| Priority date | — |
| Expiry date | Aug 15, 1997 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB29L2031/772
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
A process for producing a plastic pipe having an oval cross-sectional shape with a high dimensional precision, which comprises conducting a roughly shaped plastic pipe having an oval cross-sectional shape, which is in the softened state and composed of a large-diameter portion, a small-diameter portion and transitional portions connecting them to each other, to a cooling tank while its shape is adjusted by being passed through a forming tube with its large-diameter portion down; cooling the form-adjusted plastic pipe in the cooling tank by dipping the large-diameter portion or both the large diameter portion and a part of the transitional portions contiguous thereto in a cooling bath; and subjecting that portion of the form-adjusted plastic pipe which is out of the cooling bath to a shower of a cooling liquid. This plastic pipe is useful for a drainage or sewage system.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.