Abstract
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.
Highlights
Hydraulic rock drills have been widely used in many applications, such as mining, coal mine roadway excavation, railway tunnel, highway tunnel and rock excavation projects in the last few years because of their high efficiency, clean and safety
On the premise of not affecting the damping performance, the key to alleviate the cavitation erosion is to avoid the occurrence of negative pressure in the secondary chamber, which depends on the dynamic characteristics of the double damping system
It can be found that the reasonable range of matching parameters alleviating system cavitation is as follows: There would be no negative pressure in damping chambers when dv[0] is 7 mm and dv[1] is greater than 24 mm
Summary
Hydraulic rock drills have been widely used in many applications, such as mining, coal mine roadway excavation, railway tunnel, highway tunnel and rock excavation projects in the last few years because of their high efficiency, clean and safety. Oh J Y et al obtained the motion curve of the damping piston and the pressure change curve in the primary damping chamber by building the AMESim model of the rock drill impact system, double damping system and rock.[13] Noh DK et al analyzed the influence of the double damping system on the impact performance of the rock drill using SimulationX software.[14,15] Daniel compared the performance of the single damping system, double damping system and tandem damping system through experiments and Hopsan simulation.[16] Based on the stress wave theory, Liu Z et al built the dynamic model of the double damping system They simulated the dynamics of drilling process of the double damping rock drill and obtained the displacement curves of damping piston and rod.[17] Lu Z et al proposed the design basis of the annular clearance, which is one of the most important parameters for double damping systems.[18] Li Y et al analyzed the dynamic characteristics of the double damping system and optimized the partial parameters.[19] Yang G et al found the cavitation erosion phenomena of the damping piston, but they failed to find out the problem nature.[20,21]. The simulation analysis was verified by a real rock drilling experiment
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