JP2886963B

PURPOSE:To obtain high productivity and reliability, like rigidity and strength, without using a separate connection part like a rivet, welding, or a screw by making a component joint, such as a joint of a frame and a corner plate or a joint of a frame and an upper tie plate, into a form of a flat bend caulking by the use of the base material of the component. CONSTITUTION:A frame 1 is formed by pressing a coated steel sheet whose both ends are coated, and the outer surface is finished by coating. Both ends on the right and the left of an upper tie plate 5 and both ends on the right and the left of an opening part 7 of the frame 1 are bent and engaged with each other to form a flat bend seam, and the upper tie plate 5 and the frame 1 are joined. A rising wall part 8 is integrally formed in the periphery of a corner plate 4, and the inserted part on the side of the corner plate 4 is folded in a manner that a top end part 9 of the rising wall part 8 curls downward. Then, a flange part 10 is integrally formed atop the frame 1, and the flange part 10 is formed by vertically folding an edge part 11 of the frame 1. Further, the rising wall part 8 of the corner plate 4 abuts the edge part 11, and both are engaged and bent.