FORMING METHOD FOR CORNER ROUND SQUARE CYLINDRICAL BODY

摘要

PURPOSE:To form a corner round square cylindrical body by restoring reaction force by blanking a developed plate of the corner round square cylindrical body, forming a bend part which becomes the first corner part in the right and left side edges, and thereafter, forming the second and the fourth corner parts to a groove shape, forming the middle part of both the corner parts to the third corner part and forming two surfaces for inserting and holding the third corner part to a reverse warp surface. CONSTITUTION:A developed plate 2 of a corner round square cylindrical body 1 is blanked from a plate material, press working is performed to the left and the right side edges 5A, 5B, and when the side edges 5A, 5B have been joined, bend parts 10, 10 which become roundness of the first corner part 6 are formed. Subsequently, by bending said parts to a groove shape by press working, the second corner part 7 and the fourth corner part 9 being adjacent to the first corner part 6 are formed. Next, the middle part of the second corner part 7 and the fourth corner part 9 are placed on a female die 12, a male die 11 is pressed by a press ram 13, the third corner part 8 is formed, and also, to two surfaces for inserting and holding said third corner part 8, a reverse warp surface which is recessed to the inside of a straight line for connecting the apexes of the second the third corner parts 7, 8 and the third and the fourth corner parts 8, 9 is provided. Thereafter, the press ram 13 is allowed to ascend, the pressing force is eliminated, and by restoring reaction force of the reverse warp surface, a gap C is closed up and formed as the first corner part 6, and the corner round square culindlical body 1 is formed.