| 摘要 |
Provided is a structure for reducing the thickness of one part of a steering column (10b) describing a hollow circular tube shape while ensuring the strength thereof. A front end section of a circular tube member (19) made from a ferrous material is subjected to a drawing process, and the inside diameter of the front end face is made smaller than the inside diameter of a section of the circular tube member (19) positioned on the inside diameter side of a section forming the rear end face of a main body part (18). A section of the circular tube member (19) near the front end is inserted through an insertion hole (25) opening on the outer side face (24) of a mold (23), and the section near the front end protrudes into the mold (23). Molten metal of a light alloy is fed into the mold (23), forming the main body part (18). After removal from the mold (23), the inside diameter side parts of the inner peripheral edge of the front end section of the circular tube member (19) protruding radially inward and the main body part (18) are subjected to a cutting process, and the inside diameter of at least the section of the circular tube member (19) near the front end is made greater than the inside diameter of the main body part (18). |
