Dynamic experimental on the influence of cutting depth of PDC cutter on stick-slip oscillation of PDC bit

The influences of cutter cutting depth and rock drillability on the stick-slip oscillation of PDC bit were researched by means of laboratory dynamic rock breaking experiment. 400 mm×400 mm×400 mm natural red sandstone, yellow sandstone, white sandstone and granite were selected as experimental samples and the relationships of cutter cutting depth and rock drillability vs. stick-slip oscillation of PDC bit were analyzed by changing the weight on bit (WOB). Torque and rate of penetration (ROP) fluctuation were taken as the characteristic parameters of stick-slip oscillation to describe the stick-slip oscillation phenomenon of PDC bit, which were treated to be dimensionless and defined as the stick-slip severity. In addition, the binary nonlinear relationship model of stick-slip oscillation and torque amplitude of PDC bit vs. average cutting depth per revolution and rock drillability was established. It is experimentally indicated that the stick-slip severity of torque is more obvious under the experimental conditions. Under the five experimental WOB, the stick-slip severity of torque increases greatly with the increase of rock drillability grade value. What’s more, the stick-slip severity of torque increases greatly as the cutting depth per revolution of PDC bit increases.