| 摘要 |
<p>PROBLEM TO BE SOLVED: To secure sufficient strength by forming a quenching hardening part on almost the entire periphery of the axial direction intermediate part of a steering shaft except an engagement part for lock and a low hardness part existing in the axial direction intermediate part of the steering shaft. SOLUTION: A key lock hole 6a corresponding to an engagement part for lock is formed at a circumferential direction location in the axial direction intermediate part of a steering shaft 4. In a portion which is a part of the steering shaft 4 and the portion where a location with respect to the axial direction coincides with the key lock hole 6a, a quenching hardening part 8 by a high frequency quenching is formed. In the quenching hardening part 8, an inside part of the key lock hole 6a and the location with respect to the axial direction coincide with the key lock hole 6a and a location with respect to a circumferential direction is prevented from existing in the radial direction opposite location of the key lock hole 6a. As a result, a hollow steering shaft with engagement member for lock which is light in weight, high in linearity and strong can be obtained.</p> |
