| 摘要 |
1,082,814. Drills. H. K. DEARBORN. Oct. 15, 1964, No. 42031/64. Heading B3C. A drill comprises an adapter 40, Fig. 1, a shank portion 11, and a cutting portion 12 having a carbide tip 13, and carbide guiding pads. The members 11, 12 and 40 are joined at 14 and 41, and each joint comprises male and female screw threads 20, 22 whose angle 25, Fig. 4, lies between 3-9 degrees. Faces 18, 23 are machined so that when the members are screwed together, chip groove 15, and coolant supply passages 16, 17, are aligned, the passages having an 0-ring placed at each joint. The male and female threads may be reversed. In a modification, a twist drill comprises sections 50, 51, 52, Figs. 7, 8, the latter section being of high speed or tool steel. The threads 56, 58 of the joints have flanks which are not normal to the thread axis. Oil may be supplied through a Y branch in the cutting tip. |
