The rock breaking technology of corless diamond composite bit mainly includes axial impact and torsional impact, which is characterized by the combination of axial impact and torsional impact and the use of the weakness of hard rock with great brittleness and impact resistance to change the traditional shear chopped rock into impact + shear chopped rock, so as to achieve the purpose of improving the efficiency of rock breaking.
The non-core diamond composite bit is pre-crushed by impact to form a crushing pit, and then the torque output of the screw motor is increased by the torsional impact module to cut the crushing pit formed by axial impact. At the same time, torsional impact can also balance the stick-slip vibration of drill pipe in the circumferential direction, reduce the accumulation of circumferential torque of diamond composite piece cored bit, and improve the life of diamond composite piece cored bit. Finally, continuous torque delivery and high frequency axial impact of diamond composite piece cored bit can be achieved, so as to improve the rock breaking efficiency of drill bit.
The combination of axial impact and torsional impact completes the rock breaking of diamond composite core-less bit. Therefore, the frequency of these two impact types is the main factor affecting the rock breaking efficiency. Suppose that the frequency of circumferential stick-slip vibration of drill pipe is f, the frequency of axial impact exerted by impactor is f, and the frequency of torsional impact is f. Ideally, the torsional impact frequency of the impactor can completely offset the stick slip vibration frequency of the drill pipe, and the axial impact frequency of the impactor should not only cover the bottom hole completely when the bit teeth break rocks, but also avoid repeated crushing of cuttings at the bottom hole. Among them, the distance between the teeth and the center of the bit, the axial impact speed, and the angular velocity of the diamond composite core-less bit. In the real drilling process, the stick slip vibration frequency of drill pipe is related to rock properties, rock buried depth, hole depth and other factors. The only controllable parameters are the axial and torsional impact frequency of the impactor. Therefore, the ideal rock breaking state can be achieved by adjusting the impact frequency of the impactor.
The above is the theoretical analysis of rock breaking technology of diamond composite coreless bit.
