SEAT FRAME STRUCTURE

PROBLEM TO BE SOLVED: To ensure enough strength of joint at welded parts, even by giving small laser irradiation coverage, in a seat frame structure to mutually join the frame structure parts by laser welding.SOLUTION: A laser irradiation direction of laser welding to irradiate to carry out joint is set to a direction along a surface extending direction of a contact face of inner flanges 23 and 27 (outside exposed surfaces 24 and 28 of the inner flanges 23 and 27) to carry out surface contact to form a joint surface. Accordingly, even if the point irradiation of laser welding of the width of laser irradiation ≤1 mm is carried out, the joint part connected by this laser welding can be extended to the range of 4-5 mm along the surface extending direction to which the contact side extends. The area of the joint part by the laser welding can be expanded to several times more than before, and even by giving the little laser flash coverage, the joint strength of the welded parts can be made enough bond strength according to this seat frame structure 20.