| 摘要 |
PURPOSE: To suppress welding distortion by forming arcuate parts at four corners defined by the edges of respective flange parts continuously to the edges and then welding the adjacent abutting parts thereby eliminating the material for forming an arcuate part except the door material. CONSTITUTION: A door material 10 is provided with an arcuate part 35 to be coupled with an abutting part 33 by projecting the edge part 34 of each flange part 32 arcuately outward at the opposite ends thereof and then a thick part 31 is bent inward. Furthermore, the flange part 32 is bent inward to abut the abutting parts 33 of adjacent flange parts 32 against each other thus forming arcuate parts 35 at four corners defined by the edge parts 34 of respective flange parts 32 continuously to the edge part 34. Adjacent abutting parts 33 are then jointed by welding. This structure eliminates the material for forming the arcuate part 35 other than the door material 10 and suppresses welding distortion. |
