Cavitation erosion of the damping piston in double damping system of hydraulic rock drill and its influencing factors

The fast response property of double damping system is beneficial to improve damping characteristics. However, the intense pressure fluctuation in damping chambers often leads to the cavitation erosion of damping piston and seriously affects the normal use of seal and rock drill. The coupling model including the damping piston, damping valve, damping accumulator and connecting pipelines was established considering the structural feature and dynamic characteristics of damping system. The cavitation erosion mechanism was revealed by the simulation results. Analysis suggested that the pipeline damping and oil flow velocity between the primary and secondary damping chamber were the critical influencing factors for the cavitation erosion. The influence on system cavitation of damping valve structure and connecting pipeline types was discussed, and the reasonable range of matching parameters was given. Pressure curves in the primary, secondary damping chamber and noise spectra of cavitation were obtained by the field rock drilling test. The simulation and experimental results had consistency. The system cavitation was detected by the high-frequency pulsating pressure signal and its power spectral density analysis. This detection method provides a new approach for studying the cavitation behavior of hydraulic rock drills.