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:
Aug. 21, 1979
Filed:
Dec. 21, 1977
Gerd P Lupke, Thornhill, Ontario, CA;
Manfred A Lupke, Thornhill, Ontario, CA;
Other;
Abstract
In order, in the molding of corrugated thermoplastic tubing, to overcome the disadvantage that pressurized air which is supplied to a zone within the tube of thermoplastic material as it is extruded from an extrusion head into the entrance of a tubular mold tunnel may tend to cause rupturing of the tube at the area immediately adjacent to the extrusion head where the tube is unsupported by the wall of the tubular mold tunnel the pressurized gas is supplied at a low pressure to a first zone within the tube of thermoplastic material to support the tube against the wall of the tunnel, and pressurized gas at different, successively higher pressures is supplied to second and third zones within the tube to urge the tube outwardly into the corrugations of the tubular mold tunnel. A gas leakage path between the second and third zones permits leakage from the third to the second zone, the pressure in the second zone being controlled by venting gas therefrom at a controlled rate.