The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Apr. 09, 1985
Filed:
Sep. 29, 1982
Manfred A Lupke, Thornhill, Ontario, CA;
Gerd P Lupke, Thornhill, Ontario, CA;
Other;
Abstract
In an apparatus for producing multi-walled thermoplastic tubing in which the inner and outer tubing walls are continuously formed by extrusion one within the other, the inner tube being urged outwardly into pressing engagement with the outer tube, the mechanism for urging the inner tube outwardly into securement with the outer tube comprises a mandrel mounted coaxially with the die for extruding the inner tube and on the downstream side of it. The mandrel has an outer surface providing a tapered end portion positioned to receive the inner tube as it is extruded, and a generally cylindrical portion positioned to urge the inner tube into securement with the outer tube. To prevent sticking of the thermoplastic material to the mandrel, the outer surface of the mandrel is maintained at a temperature lower than the molding temperature and is transversely ribbed.