| 摘要 |
This projection bolt (1), which is for welding by electric resistance welding to a thin plate member (8), is formed from a shaft part (2), a circular expanded diameter part (3), and a welding protrusion (4) comprising an initial melting area (4a) with a tapered portion (6), and a main melting area (4b). Either the ratio of the volume of the initial melting area (4A) to the volume of the plate member (8) within the same diameter as the initial melting area (4A) is selected, or, the ratio of the circular area of the initial welding area (4A) to the plate thickness of the plate member (8) is selected, and after completion of welding, a gap is arranged between near the outer periphery of the expanded diameter area (3) and the surface of the plate member (8), and thereby, the amount of melting in the plate thickness direction is optimized, and the problem of coatability near the outer periphery of the expanded diameter area is solved, which handles the problem of rusting. |
