| 摘要 |
1474877 Screwdrivers BULTEN KANTHAL AB 4 March 1975 [8 March 1974] 8878/75 Heading B5N [Also in Division F2] A screwdriver bit 15 has an external spline drive formation comprising a cylinder with a plurality of equiangularly spaced axial grooves each defined in part by a part-cylindrical surface, the regions of intersection between the grooves and the outer cylindrical surface of the bit being sharp-edged. The grooves may be formed by a single grinding or milling operation, e.g. by a cutter 16 on a shaft 17. |
