| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a door frame which is formed by roll forming of a belt-like plate material, and which is excellently rolled, when the belt-like plate material used for a door frame is made a coil material. <P>SOLUTION: A shape formed by expanding a cross section orthogonal to the longitudinal direction of the door frame, includes: a first thick plate 55 of a maximum thickness; a second thick plate 56 with the same thickness with the first thick plate 55; and a thin plate 53 which is thinner than the first thick plate 55 and the second thick plate 56. The first thick plate 55 is formed only at one side of a center line in the longitudinal direction of the cross section. At least a part of the second thick plate part 56 is formed at the other side of the center of the longitudinal direction of the cross section. The thin plate 53 is positioned between the first thick plate 55 and the second thick plate 56. <P>COPYRIGHT: (C)2012,JPO&INPIT |
