Effects of the Working Fluid Inertia on the Hydrohammer Operational Parameters

Abstract

The study objective is to justify the parameters that ensure efficient energy conversion of the hydrohammer. Research methods include review, analysis and generalization of research results and experience in designing hydraulic devices; mathematical modeling based on laws of kinematics and dynamics of solid, liquid and gas; theoretical research based on numerical experiments. The novelty of the work is in the development of a mathematical model of a hydraulic hammer describing the cooperation of the percussive mechanism, distributor, hydraulic pneumatic accumulators and hydraulic drive. The study results include a mathematical model of a hydraulic hammer that takes into account the dynamics of its body and reflects the features of the working cycle of a hydrokinematic circuit with a controlled chamber of the working and reverse stroke; the numeric results of the mathematical model and experimental studies; dynamic analysis of the piston pin during the reverse stroke. Conclusions: the hydrohammer operation is influenced by accidental or purposeful changes in certain parameters of the hydraulic drive, which must be taken into account at the design stage of its subsystems in order to find a rational area of operation; one of these parameters is the inertia of the working fluid; formed during transition periods, inertial forces have a significant impact on the main parameters of the hydrohammer piston pin movement and dynamics of the power pulse hydraulic system; the time of filling the working cavity of the hydraulic cylinder of the striker is determined, the degree of influence of the working fluid inertial component on the time of the piston pin movement on the magnitude of the working stroke is defined.