Pipe body and forming method of the same

A metal pipe comprising a bent metal plate having

• parallel first and second edge sections in opposed and engaged position;
• a male portion formed on said first edge section and having a pair of divided pieces;
• and
• a female portion formed on said second edge section and having a space with a back portion and broadened toward the back portion from an open end of said space, a projection projecting toward said open end from the center of the back portion, and a pair of engaging walls formed on said open end;
• wherein said pair of divided pieces are inserted in said space through said open end and are deformed in a mutually spaced direction by insertion of said projection between said divided pieces, with clearances between said divided pieces and said projection and with said pair of engaging walls engaging said pair of divided pieces;
• wherein convex engagement sections projecting from said second edge section are provided on said pair of engaging walls, and concave engagement sections opposing said convex engagement sections are provided on said male portion;
• and
• wherein said pair of engaging walls are deformed to pinch said pair of divided pieces from both sides thereof due to engagement of said concave and convex engagement sections.

A metal pipe comprising a bent metal plate having

• parallel first and second edge sections in opposed and engaged position;
• a male portion formed on said first edge section and having male engagement sections, concave engagement sections being provided on said male portion;
• and
• a female portion formed on said second edge section and having a space with a back portion and broadened toward the back portion from an open end of said space, and a pair of engaging walls formed on said open end, convex engagement sections projecting from said second edge section and opposing to said concave engagement sections being provided on said pair of engaging walls;
• wherein said male engagement sections are inserted in said space through said open end and are engaged by said pair of engaging walls and are deformed, with clearances between said male engagement sections and said female portion, said pair of engaging walls being deformed to pinch said male engagement sections from both sides thereof by engagement of said concave and convex engagement sections.

A metal pipe produced by a method including bending a metal plate having mutually parallel first and second edge sections and opposing said first and second edge sections, said method comprising:

• a step for forming on said first edge section a male portion having male engagement sections to be subjected to deformation and for forming on said second edge section a female portion having a space with a back portion and broadened toward the back portion from an open end of said space for inserting said male engagement sections, and a pair of engaging walls formed on said open end for engaging said male engagement sections;
• a step for disposing said first and second edge sections in an opposed relation to each other by bending said metal plate;
• and
• a step for engaging said first and second edge sections with clearances between said male engagement sections and female portion when said male engagement sections are inserted into said space, convex engagement sections projecting from said second edge section being pre-provided on said pair of engaging walls, and concave engagement sections opposing to said convex engagement sections being pre-provided on said male portion, said pair of engaging walls being deformed to pinch said male engagement sections from the both sides thereof by engagement of said concave and convex engagement sections.