Patent ID: 6908270

Claim:
In a combination of a self-locking bolt fastening a lockable member, the improvements of the self-locking bolt comprising: a head having a locking function; and a threaded part extending from the head and provided with an external thread of a pitch P, the external thread being such as to mate with an internal thread of the lockable member; the locking function consisting of n locking projections at equal angular intervals on a bearing surface of the head, the locking projections being separated from one another by planar portions of the bearing surface, heights of the locking projections from the bearing surface increasing gradually in a direction opposite a fastening direction in which the head is rotated for the fastening to maximum heights, edges at the maximum heights, the heights of the locking projections decreasing asymmetrically steeply as compared to the increasing gradually from the edges in the direction opposite the fastening direction, the maximum heights of the edges being nearly equal to or less than P/n, a total area of the planar portions being larger than a total planar projected area of the locking projections, and the self-locking bolt having a small diameter not larger than 6 mm, wherein the locking projections sink fully into the lockable member for the locking function.