Die for extrusion of blown plastic film
US5261805A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Feb 16, 1988 |
| Grant date | Nov 16, 1993 |
| Priority date | — |
| Expiry date | Feb 16, 2008 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB29C48/70
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
The invention relates to the kind of die which has many helical grooves (40) spiralling around a mandrel, and to a new way of feeding the liquid resin from the main supply duct (48) to the grooves. Instead of the usual one groove to one conduit relationship, in the invention the channels (41) to the grooves are intercalated with the conduits (47). Each groove is fed via feed-channels (45,46) from two of the conduits, and each conduit feeds two of the grooves. The result is that the cooler liquid resin from the walls of the main duct is constrained to move to the centre of the stream in the groove. The arrangement leads to an improvement In the homogeneity of the resulting film.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.