Modeling And Simulation Of The Working Performance Of A Pneumatic-hydraulic Hammer

Pneumatic-hydraulic hammer is one of the high-efficiency hydraulic rock-breakup machines. It features prominently in rock-breakup machine market with a series of features, including compact structure, high energy density, good adaptability and high reliability. Pneumatic-hydraulic impactor is the core of the hammer. Its motion and output characteristics have a great influence on the breakup efficiency. This thesis takes Sunward’s SWHB series as a research object to carry out a profound and meticulous research on the mathematical model, simulation model and motion characteristics of this kind of hammer. The main works are as follows:The motion characteristics of pneumatic-hydraulic hammer are analyzed by the design theory of the hydraulic impactor and the kinematics equations of all the mechanisms are obtained. After the analytical method of hydraulic cavity is put forward, the front and rear chambers of piston as well as the high pressure cavity of distributing valve in different states are analyzed to establish the corresponding mathematical model.Model establishing principles and measures are advanced based on the operating characteristics of the pneumatic-hydraulic hammer. Inner structure and motion characteristics are analyzed. After calculating the conveyance area and referring to the actual working conditions, the simulation model of the hammer is established by software AMESim.Taking SWHB58as a research object, the experiment is done by air pressure method. By comparing the results of the experiment with that of the simulation, the reliability and validity of the simulation model are verified. Based on this, parameters such as initial air pressure and input flow are changed, and the curve of impact characteristics is worked out by model simulation. The thesis also makes researches on the influence of initial air pressure and input flow on this kind of hammer. In addition, many other factors are studied, such as piston mass, operation area of hydraulic oil in the ante-chamber, positive or negative opening of distributing valve and size of accumulator and nitrogen chamer, thus making a discuss on the influence of key structure parameters on output characteristics.In this thesis, a new way to analyze how hammers work is advanced. The research findings are of practical value and provide theoretical guidance to the design and manufacture of hammers.