| 摘要 |
In a modification to the cutter disclosed in UK Patent application No. 20 80 162A, the back-off surface (56) and therefore the inner and intermediate cutting edges (34, 36) are inclined radially inwardly and axially rearwardly at an angle (ab) between +10 DEG (Figure 10) and -3 DEG (Figure 14). In the case of a rapid feed rate producing thick chips which do not bend easily, these angles cause the chips to be directed closer to the vertical to facilitate their entry into the flutes (22). An additional back-off surface (86) on the outer cutting edge (38) is inclined upwardly and rearwardly at a high inclination angle (c) of 40 DEG to 45 DEG to assist in directing the chip cut by the outer edge (38) away from the wall of the hole being cut and reduce the risk of chipping of the cutting edge. <IMAGE> |
