The Kinematics And Dynamics Research Of Mine-used Rotary Drill Bit

When a rotary drill is used to break rocks, the working part is the cone bit whose performance will exert a direct influence on the quality, speed, and cost of drilling. The movement of the cone bit is very complicated in the bottom of the holes. What matters is that the interaction between the cone bit and rocks is not clear. Therefore, it is of necessity to conduct a study on the kinematics and dynamics of cone bits.This thesis first presents the automated GUI interface for the cone bit structure parameters. Then the three-dimensional solid model of the cone bit is established by means of PRO/E and its kinematic simulation is carried out in ADAMS. The motion of the pillar gear reflects the cutting area and depth of the cone bit on rocks. Besides, the author proposes ways of determining the optimal bit speed ratio with the patterns of holes in the bottom while drilling and analyzes the influences of the gear structures and the bit speed ratio on breaking rocks. The geometric model of the cone bit is established in the cone bit composite cylindrical coordinate system. Furthermore, on the basis of the motion equation of cone bits, the influences of shaft angles on the movement of cone bits are analyzed in order to determine the optimal shaft angles of mine-used cone bits, make a comparison of the results of the simulation, and testify their reliability.With the bits being seen as the elastomer and rocks as plastic brittle body, the contact model of the longitudinal vibration of the alloy pillar gears and rocks in the bottom of the holes is established and its finite element simulation is conducted by using ANSYS/LS-DYNA. The huge collision generated by longitudinal impacts is an important cause of the abnormal failure of the cone bits. The destruction of alloy pillar gears begins in their top area and then gradually extends to the internal parts, which may lead to the breaking-off of the gear tips. The study of the crushing pits is helpful for the deduction of the crushing process of plastic and brittle rocks and provides a new method for the study of optimal gear spacing of cone bits to make optimal efficiency of breaking rocks.