Simulation and experimental study on temperature and stress field of full-sized PDC bits in rock breaking process

The failure rate of polycrystalline diamond compact (PDC) bits mainly depended on the cutting temperature and the force of the cutting teeth. It was of great value to study the distribution of temperature and stress fields on the PDC cutting teeth during rock breaking for exploring the failure mechanism and improving the service life of the bits. In this paper, the finite element was used to simulate the thermal-structural coupling of rock breaking process of the full-sized PDC bits. The simulation results show that the high temperature region of the cutting teeth was offset from the top of the crown to the outside of the cutting teeth during drilling process, and the high temperature region of the cutting teeth was fan-shaped. The failure reason of PDC cutting teeth was analyzed by simulation. The maximum principal stress of PDC cutting teeth existed in the interface between the polycrystalline diamond (PCD) layer and the cemented carbide (WC-Co) substrate, fracture and delamination were concentrated at the top of the cutting teeth crown. The experimental results show that the temperature of cutting teeth when drilling the granite was about 2 times that of the marble and 3 times that of the sandstone under the same conditions. The simulation results were basically consistent with the experimental results, which verified the accuracy of the finite element model simulation analysis method.