Simulation Analysis of Contact Stress Variation of PDC Tooth Surface at Different Rotational Speeds

When drilling in deep hard-rock formation, polycrystalline diamond compact (PDC) drill bit has the phenomenon of fracture of PDC tooth due to high stress on tooth surface, while the current research on PDC tooth breaking focuses on the efficiency of PDC tooth breaking, and less on the change of contact stress on tooth surface when breaking rock. The rotational speed is an important mechanical parameter in oil drilling operation, in order to deeply study the influence of rotational speed on the contact stress of the tooth surface when PDC tooth breaks the rock, we established the PDC single-tooth rock-breaking model, investigated the rock-breaking process of the PDC tooth under different rotational speeds, and analyzed the change of the stresses of the rock and the PDC tooth when the PDC tooth breaks the rock. The results show that in the process of rock cutting by PDC teeth, the destruction of rock is gradual, the size and position of the contact surface between rock section and PDC teeth change constantly, resulting in the existence of stress concentration and impact on the surface of PDC teeth, the maximum value of the stress can reach 1194 MPa when the rotational speed is 100 RMP, and as the rotational speed increases, the speed of rock being broken is accelerated, and when the rotational speed is greater than 90 RMP, the The increase of rotational speed will cause more violent impact creation on the PDC teeth when breaking the rock, which is not favorable to the service life of the drill bit. The relevant findings can help to reveal the intermediate damage mechanism of PDC teeth under different rotational speeds when drilling in deep hard-rock formations and provide a reference for the scientific selection of rotational speeds.