| 摘要 |
<p>A percussive drill bit (101) has a steel body (102) with tungsten carbide buttons (103, 104) mounted therein. The steel body has a longitudinal rotational axis (105) having a bit face radius 202. In addition, a gauge surface 107 surrounds the bit face and is inclined at a gauge angel. Face buttons 204, 205, 206 are mounted in the bit face substantially equally displaced around a circumference having a radius that is less than the bit face radius. For each face button eg 205, a first gauge button 207 is located in said gauge surface displaced in a clockwise direction and a second gauge 208 button is located in the gauge surface displaced in a counter clockwise direction, so as to define a wing with wing edges 209, 210. A primary flushing flute 108 cuts into the gage surface between each of the first gauge button and the second gage button to an extent such as to reach the bit face radius. The bit includes a drop centre hole 211 and flushing holes 213, 214, 215 located between the wing edges.</p> |
