Influence mechanism of polycrystalline diamond compact bit temperature rise based on thermo-fluid–solid coupling

Abstract

In order to improve the drilling performance of polycrystalline diamond compact bit and prolong its service life during drilling in coal rock under the action of wind cycle, the theoretical calculation model of polycrystalline diamond compact bit cutting teeth temperature was derived based on the theory of tribology and heat transfer. The theoretical temperature field of polycrystalline diamond compact bit-cutting teeth was analyzed. Using the joint simulation of EDEM–FLUENT, the temperature variation law of polycrystalline diamond compact bit cutting teeth under the thermo-fluid–solid coupling was analyzed to verify the validity of the theoretical calculation model of polycrystalline diamond compact bit cutting teeth temperature. By building a rotary drilling test platform and conducting drilling experiments on polycrystalline diamond compact bit under different drilling parameters respectively, the correctness of the theoretical model and the simulation data were verified. In addition, a response surface analysis model was established to study the influence of different drilling parameters on the polycrystalline diamond compact bit cutting teeth temperature during drilling in coal rock. The analysis results show that the influence degree of various drilling parameters on the polycrystalline diamond compact bit cutting teeth temperature from large to small is drilling pressure, drilling speed, coal rock properties, and wind speed. Compared with the working condition without wind cycle, the drilling efficiency of polycrystalline diamond compact bit can be increased by 14.38% and the temperature is reduced by 8% when it drills in coal. The drilling efficiency of polycrystalline diamond compact bit can be increased by 17.79% and the temperature is reduced by 10.5% when it drills in coal gangue.