Method and apparatus for forming a double walled thermoplastic tube with integral bells
CA 2072663 C · Owner: Lupke, Manfred A. A. · Inventors: Lupke, Manfred A. A.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A double wall plastic pipe is produced from an extruder with a nozzle having a first orifice and a second orifice downstream of the first orifice feeding into a moving mold tunnel having a first region with a corrugated mold surface and a second region with a belled mold surface. The second region also has openings through the mold wall. A first parison of molten thermoplastic material is extruded from the first orifice into the mold tunnel with the first parison being forced against the corrugated mold surface to shape alternating crests and troughs and against the belled mold surface to shape a bell in the first parison in forming respectively corrugated and cuffed pipe parts. The first …
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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
- Filed June 29, 1992 and granted November 16, 1999. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended June 29, 2012.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by June 29, 2014.
- 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.