Die for extrusion of blown plastic film
CA 1279965 C · Owner: Polysystem Machinery Manufacturing Inc. · Inventors: Gates, Peter C.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
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.
Read the whole patent
Listed from its CIPO record in Patent Yard's archive of Canadian patents past their term. Its claims, description and drawings are in the CIPO record and on Google Patents, and the Claude kit works from them.
Why it's free to use
- Granted February 12, 1991. A Canadian patent filed before October 1, 1989 lasted 17 years from grant, so its term ended February 12, 2008.
- We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
Timeline
Timeline From CIPO dates
Sources & verification
Official CIPO records
Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.