| 摘要 |
1,126,103. Drills. A. FISCHER. 27 May, 1966 [31 May, 1965], No. 23957/66. Heading B3C. A drill bit has a shank 4, Fig. 1, and a tip 3, the shank being adapted to be withdrawn from the bored hole, to thus leave the tip embedded in the hole. The tip may have anhexagonal socket (2a), Fig. 3 (not shown) to match the hexagonal end 2 of shank 4, or it may be of oval shape (2b), Fig. 2 (not shown). In a modification, the shank (5), Figs. 6, 7 (not shown) is hollow with a slot (6) and locking projection (7), and a crown shaped drill bit (8) has projections (9), (10), which cooperate with recesses (11), (12), on the shank. |
