The Coupling Research Between Impact System And Double Damping System Of Heavy Hydraulic Rock Drill

Hydraulic rock drill was a kind of drilling equipment breaking rock by impact and rotary. Its working medium was hydraulic oil. Now it is widely used in Mines, tunnels and buildings. As the development of large-scale mining and Tunnel excavation, hydraulic rock drill with high power and high frequency was the important developing direction. So the heavy rock drill will be the main trend to improve the efficiency of mining and reduce the labor intensity.Heavy rock drill was the research object of this thesis. To solve the problem of the coupling of impact system and double damping system, the hydraulic rock drill’s kinetic model, system response model and the stress wave transmission model were built to research the optimization of the rock drill’s system and the intense research on the coupling of impact and damping. The correctness of the models was demonstrated by the experiment.The hydraulic rock drill’s kinetic model was resolved into two parts, the impact system and the double damping system. Each of the two systems was researched on the dynamic characteristics and system optimization. Besides, the relationship of the impact system and the double damping system on dynamic characteristics and energy conversion were studied too.The concept of the reversing point’s lead value was put forward. An overlapped oil distributing valve was designed, though the under lapped distributing valves were widely used in domestic hydraulic rock drills. The design was on the basis of the simulation of the rock drill. By the simulation, pressure curves of the former chamber and rear chamber of the impact piston, the left and right chamber of the valve were received. In addition, damping piston’s floating character affected the reversing point’s lead value, which was also a factor in the design of the overlapped oil distributing valve. Then, the best striking section of the impact piston was calculated. The dynamic characteristic of the impact system was optimized coupling ballistic motion and the accumulator.For the phenomenon of drill rod rebound which was caused by the heavy power and high frequency of the heavy rock drill, the mechanical model of damping system was established, For the control system perspective, the state space model of the double damping system was established, the model was with the rebound velocity of the damping piston as the input signal and the pressure in the 1st order and 2nd order damping chambers as the output signal. The effect of the double damping system was analyzed, which was caused by the annular clearance, initial charge-nitrogen pressure of accumulator and inlet pressure of damping system.Optimization analysis was made for the Selection of performance parameters of the double damping system. Applying the Fourier series, a constantly changing incident stress wave model was established. Experimental method of strain gauge was used to test the incident stress wave, and the incident stress wave model was modified according to the experimental results. The motion law of damping piston and the change rule of the pressure in the 1st order and 2nd order damping chambers was analyzed. The performance parameters of the double buffer system are optimized by using the multi-objective optimization method.Pressure test of heavy hydraulic rock drill was designed, and the judgment of impact point was analyzed. The velocity and displacement curves were gained by the integral, and got the impact velocity of impact piston. The correctness of the model was verified by a contrast between test and simulation.The transformation law of calculating energy conversion course between impact system and double damping system was analyzed. The balance of energy’s absorption and release of double damping system was discussed, and the overall system energy conversion was excellence.