| 摘要 |
1,147,786. Dental drills. M. E. NELSON. 21 June, 1966 [24 June, 1965], No. 27709/66. Heading A5R [Also in Division B3] Dental drills are shaped from individual metal tubes by swagging, the drills comprise a shank tapered at one end to form a frusto-conical portion (27) on which the head of the drill is formed or secured. The head 26a may be formed during the swaging process from a portion of the tube adjacent the smallest diameter end of the frustoconical portion (27), the tube bore remaining to form an axial passage 33a. The tube may be swaged at one or both ends to close the passage. Bores 34 may extend radially from the passage to the exterior of the head for conducting coolant from the passage to the exterior of the head, which may carry an abrasive e.g. carborundum or diamond bort. Alternatively the head is made separately from carbide and provided with longitudinal flutes (38, Figure 7) which define cutting edges (39), and an axial and radial bores (33c, 34c). It is welded or butt blazed to a flange (37) which is formed on the small diameter end of the frusto-conical portion (27c) of the shank during the swaging process, the axial passage (33c) of the head registering with the axial passage in the shank. |
