| 摘要 |
A percussion drill bit 10 has a cutting face 22 with cutting elements which may be in the form of buttons 20 (e.g. carbide material) or blades. The bit has a cylindrical body with helical flutes 32, which extend into a reduced diameter neck 30 disposed between face 22 and the cylindrical body. The bit 10 includes holes 28 extending therethrough to direct flushing medium (water) to the face 22 and a threaded socket for receiving threaded end of the drill rod. The bit 10 can be combined in a drill string with an extension body 12 and a rod connector 16, all of which have similar helical fluted surfaces. The body 12 has a threaded end received in the threaded socket of bit 10, and a threaded socket to receive therein a drill rod 14. The connector 16 has threaded sockets at its ends for receiving the rod 14 and a rod 18. The rods 14, 18, body 12 and bit 10 all have flushing passages therethrough. The angle of the helix defined by flutes 32 is between 20 DEG and 30 DEG . <IMAGE> |
