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:
Nov. 10, 1987
Filed:
Sep. 09, 1986
Applicant:
Inventor:
Kenji Nakajima, Osaka, JP;
Assignee:
Ariyoshi Nakamura, Saitama, JP;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
B21C / ;
U.S. Cl.
CPC ...
72 50 ;
Abstract
A curved connecting pipe for ducts is proposed which can be manufactured at low cost. It is made by rolling spirally a long metal strip having wide portions and narrow portions alternately so that the wide portions will meet at one edge of the strip and the narrow portions will meet at the other edge. A single flange formed along one edge is received in a double flange formed along the other edge. An apparatus for making the connecting pipe is disclosed. In another embodiment, a flat edge of the strip is rested on a recessed edge and welded together.