| 摘要 |
This drill bit comprises a plurality of rollers provided with cutting teeth or inserts. At least one vertical fluid flushing jet is directed towards the hole bottom between two adjacent rollers and at least one upwardly directed education jet is created. The nozzle delivering the flushing jet opens at a distance from between 1/3 H and 4/5 H from the hole bottom, H being the height of the cutters measured in a direction parallel to the bit axis. |
