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. 10, 1979
Filed:
Aug. 31, 1977
Wataru Midzutani, Kitakyushu, JP;
Toshio Kikuma, Mizumaki, JP;
Koe Nakajima, Nakama, JP;
Seiichi Sasahira, Kitakyushu, JP;
Nippon Steel Corporation, Tokyo, JP;
Abstract
A method and apparatus for manufacturing metal pipe. The edges of a metal plate are bent up slightly, and the thus bent plate is then bent into a U-shape cross-section blank. The U-shape blank is finish-formed into an O-shaped blank with the longitudinal edges opposed to each other in a position for welding by placing one end of the U-shaped blank into at least one two-part die the parts of which are movable toward and away from each other. The die has at least one portion with the shape of the opposed die recesses defining a reforming area on one end of the die portion which has an O-shaped cross-section, a finish forming area in the middle of the length of the die portion having an O-shaped cross-section, these O-shaped cross-sections being the shape of the O-shaped blank, and a transitional area at the other end of the die portion having a cross-sectional shape which changes gradually from an O-shape adjacent the finish forming area to an oval shape elongated in the direction of movement of the die parts at the other end of the die portion. The transitional area is relatively short as compared to the remainder of the die parts. This one die portion is shorter than the length of the blank. The U-shaped blank is placed in the die with the elongated dimension of the cross-section corresponding to the elongated dimension of the oval shape and with one end of the blank at the one end of the die portion, and the two part die is closed for shaping the U-shaped blank into a blank having an O-shaped cross-section reformed portion on said one end of the blank, a finished O-shaped cross-section and a transitional section. The two part die is opened and the thus formed blank along the die until the edge of the transitional section of the blank is at the end of the finished forming area of the die portion adjacent the reforming area. The steps of positioning the blank and opening and closing the die are repeated until the blank is completely formed into an O-shaped cross-section, and the opposed edges of the plate are then welded to produce the O-shaped cross-section blank.