Experimental study on PDC single-tooth flexible vibration reduction effect

Abstract

In oil and gas drilling engineering, when PDC bit is drilled into inhomogeneous strata, soft and hard alternating strata, and directional drilling and other complex working conditions, it often encounters frequent impact loads, resulting in abnormal failure accidents, which greatly reduces the performance of the bit. The technical concept of flexible cutting rock breaking is to reduce the stiffness by setting elastic elements, reduce the impact load amplitude suffered in the cutting process to a certain range, and achieve the purpose of extending the service life of the bit. The effects of cutting depth, rake angle and disc spring series combination on the damping effect of flexible damping unit are analyzed through experiments on limestone. The results show that the flexible vibration reduction cutting can effectively reduce the peak cutting load and load fluctuation by 20%~35%. When the flexible tolerance ratio is near 67.6%, the flexible vibration damping effect is the best. The effect of flexible vibration reduction is positively correlated with the combined stiffness of the disc spring and the rake angle. The optimum stiffness combination of the elastic elements is 2 A-type disc springs in series and the optimum rake angle is 15°.