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:
Jun. 25, 2002
Filed:
Oct. 21, 1999
Eugen Schwarzkopf, Lüdenscheid, DE;
Hotset Heizpatronen U. Zubehor GmbH, Ludenscheid, DE;
Abstract
A method of making a heater element has the steps of inserting into a smooth tubular casing a heating wire, filling a space between the wire and the casing with a compressible insulating mass, and closing ends of the space to confine the mass in the casing. Then the casing is radially inwardly compressed to form therein a successive of radially outwardly open annular grooves extending circumferentially fully around the casing and thereby radially compressing the insulating mass. The casing is formed with a succession of such grooves, which can be of V-shape and which are each endless so that the casing is corrugated. Alternately the grooves are interconnected helically. Either way in accordance with the invention the grooves form axially relatively long and radially relatively thick outer rings and axially relatively short and radially relatively thin inner rings.