| 摘要 |
Construction is achieved that is capable of ensuring strength while making the thickness of part of a hollow cylindrical shaped steering column 10b thin. A drawing process is performed on the front-end section of a cylindrical member 19 that is made of an iron alloy to make the inner diameter of the front-end surface smaller than the inner diameter of the portion of the cylindrical member 19 that is located on the inner-diameter side of the portion that forms the rear-end surface of the main body portion 18. A portion near the front end of the cylindrical member 19 is inserted through an insertion hole 25 that is opened in an outside surface 24 of a mold 23, and the portion that is near the front end protrudes inside the mold 23. A molten light metal alloy is fed into the mold 23 to form a main body portion 18. After removing the main body portion 18 from the mold 23, a machining process is performed on the inner circumferential edge of the front-end section that protrudes in the radial direction of the cylindrical member 19 and the inner-diameter side portion of the main body portion 18 to make the inner diameter of at least the portion near the front end of the cylindrical member 19 equal to or greater than the inner diameter of the main body portion 18. |
