Mechanical characteristics and test of rotary drilling of PDC anchor bit

For the construction requirements of the fast and accurate drilling of anchor hole in a coal roadway, the main mechanical factors are analyzed in theory through the establishment of PDC anchor bit rotary drilling mechanics model. The results show that the axial force of the PDC cutting tooth increases with the increase of the penetration depth, and shows the trend of first decreasing and then increasing with the increase of the cutting angle. When the friction coefficient of the coal-bearing strata is 0.20 to 0.43, the optimum cutting angle is from 15.0° to 18.3°, and the axial force and the tangential force are minimal under the same penetration depth. Furthermore, based on the mechanical properties of coal-bearing strata, the rock breaking conditions under the action of PDC cutting teeth are proposed, and the relationship between axial force and tangential force at different penetration depths is obtained. The actual drilling test of simulated rock samples was carried out by the self -developed drilling laboratory bench. The test results verified the correctness of the rotary drilling mechanics model. The research results provide theoretical basis for the optimization design of PDC anchor bit, the improvement of drilling efficiency and precision of anchor hole, and the prediction of the change of drilling axial force and tangential force.