SEAT FRAME, SEAT STRUCTURE, AND METHOD OF MANUFACTURING SEAT FRAME

摘要

A seat structure manufacturable at low cost by utilizing a seat frame having pipe parts formed by bending sheet metal materials and having high strength and a method of manufacturing the seat frame. The seat frame (10) comprises the pipe parts (210), (220), and (230) formed by forming the sheet metal materials in roughly cylindrical shapes and welding at least a part of the end edges of the cylindrical sheet metal materials. The pipe parts (210), (220), and (230) partially comprise portions (210b), (220b), and (230b) formed in recrystal grain structures refined by a heat treatment and a strain processing in the welding. Since the pipe parts partially comprise the portions formed in the recrystal grain structures, the strengths and yield stresses of the portions are increased, and the deformation and damage of the pipe parts due to the embrittlement of weld parts can be reduced irrespective of the fact that the pipe parts are formed by forming the sheet metal materials in the roughly cylindrical shapes. As a result, since extrudedly molded hollow pipe materials must not be used, the seat frame can be manufactured at low cost.