METHOD FOR FORMING DEFORMED CROSS-SECTION AND FORMED ARTICLE OF QUADRILATERAL CROSS-SECTION EXHIBITING EXCELLENT SPOT WELDABILITY

摘要

It is difficult for a forming technique of complex cross-section shape of the related art to obtain a complex cross-section forming article having high spot weldability and high dimensional accuracy. More specifically, a tubing material 10 having a tensile strength (TS) of 590 MPa or more is crushed by complex cross-section shape forming dies 1 and 1A each having at least one surface with a flat portion in a state in which no internal pressure is loaded or an internal pressure of 50 MPa or less is loaded to the tubing material by liquid, and an internal pressure such that the maximum internal pressure becomes higher than or equal to the following P min [MPa] is continuously loaded by the liquid so as to form the tubing material into a complex cross-section shape. P min = 0.045xTS