| 摘要 |
843,125. Drills. ROWLEY, B. W., WIEDEMAN, J. E., RHODES, M. G., [trading as JANCY ENGINEERING CO.]. April 8, 1957 [April 23, 1956], No. 11401/57. Class 83 (3). A drill for thin material has a number of angularly spaced cutting points 14 in a plane perpendicular to the drill axis, the drill being relieved radially inwardly and axially rearwardly of each cutting point by an inclined flat surface 16. The shank B, Fig. 7, has a stepped bore 24, 30, and houses a flanged centre C urged against a flange 28 by a spring S retained by a screw P. The cutting points 14 are diametrically opposite each other and their relieved faces 16, Figs. 1 and 3, lie along planes X-X crossing at an angle a which may vary from 52¢ to 85 degrees. The cutting edges 26, Fig. 5, may be offset as shown from a diametral plane. |
