| 摘要 |
<p>This rotary percussion drill has main spiral grooves (4,5) for cuttings and a hard metal cutter (7,21) attached to a one-piece cutter plate (6). The base (10) of the cutter plate is fixed into a groove (9) passing through the diameter of the shaft (1), in its end face (3). The base of the cutter plate has a central thickening, its cross-section exhibiting a part-circular keying projection (12). The groove cut across the drill shaft has a corresponding recess (13). The base of the cutter plate is centralised by keying.</p> |
