| Water is a kind of environmental protective transmission medium with clean, nontoxic, safe and inexpensive performances. Water as a medium of hydraulic drive has been successfully applied to food, coal-cutting, rock/mineral mining, metallurgy, ocean development, pharmaceutical and other industries. In recent years, with the development of the research for water hydraulic system of the hydraulic ram pump, the application domain of water hydraulic transmission is broadened considerably. In mining industry, with the increasing of mining depth, in deep excavation mining of metallic mine with hard rock clean water is needed to introduce from ground surface or higher level to remove the dust and exhaust air. If we could make full use for the potential energy of the dropping water from ground surface to drive the hydraulic rock drill and even the other operating machinery, the energy consumption and production cost could the reduced considerably. In this case, water-powered rock drill and its crucial impactor would-be the key for the development of this technology.The impact mechanism of water-powered rock drill experiences high frequence impact load, so it is necessary not only to solve the problems of low in visicosity, high in leakage and poor in lubrication property for the high pressure driving water, but also to study and develop the materials, which can withstand high pressure impact load, possesses high corrosion resistance and friction-wear resistance, etc., for fabricating ram-cylinder and several seal parts of water-powered rock drill. Then two crucial technologies, selecting materials for impacting-friction pair and controlling water leakage, are selected to research.The principles for selecting friction-pair material and matching method were proposed based on the analyzing of water-powered impact mechanism movement and forces applying state, and composite material-stainless steel match was introduced as a novel matching schema for friction pair of water-powered rock drill. According to the working schema for friction pair of hydraulie rock drill. According to the working conditions of water-powered impact mechanism, three kinds of carbon fiber reinforced polite trafloethylene (PTFE) composite materials wase prepared with different formulations, and tribological characteristics of the PTFE composite and stainless steel were investigated by using ring-lock friction test machine, metal lagraphy, SEM and EDS, and so on, to analysis the influencer of appling load, friction time, carbon fiber content, molybdenum disulfide content, coper powder content, etc., on friction coefficient and wear quantity of the PTFE composite materials. It is found from the study that the PTFE composites with carbon-fiber content of 15% mass fraction and the high temperature nitride treated 0Cr17Ni14Cu4Nb got a friction coefficient of 0.011 respectively, which is the lowest one between all of the similar materials in China.15 min before testing, the friction coefficient decreased with the increase in load; after 15 min, the friction coefficient basically stailize at around 0.011-0.014, indicating the stainless steel surface has been covered with carbon fiber after 15 min, the friction between the two fundamental materials changes into the friction between carbon-carbon and thus a very low coefficient of friction is gotten. Main wear mechanism of the PTFE composite material containing carbon fiber is fatigue wear, the higher the carbon fiber content, the lower the friction coefficient; the applied load inereases from 100N to 250N, the wear quantity increases with load decrease, starting from 250N wear increases with load increase.Corrosion protection property of three kinds of stainless steel either heat treated or high temperature nitrigenized was investigated using linear poparization method, and then compared with another stainless steel with no treatment introduced just now by using electrochemical corrosion experiment. The results show that the corrosion-protection performance of the stainless steel either heat treated or high temperature nitrigenized is decreased. The corrosion protection performance of the 316L and 2205 stainless steel is better than that of 17-4PH. Several kinds of corrosion-protection methods for metallic parts surface, including QPQ salt-bath compositive nitrigenizing treatment, thermal spraying nano-ceramics, hard chrome plating processes were tested, the results show that, the QPQ salt-bath compositive nitrigenizing treatment method could satisfy the requirenment of corrosion-protection for the cylinder, connector, head and other non-direct contact parts materials. In addition, supposing that some improving measures are used to improve the combinational force and the densification ability of the chrome-plated surface layer, the surface hard chrome plating method can be used to treat the impacting pistom (ram) of the rock drill whose impacting energy is lower than 120J.The theoretical analysis, experimental research and simulation analysis based on AMESim for pressure water flowing in annular gap show that the formula for calculating the laminar flowing quantity in annular gap proposed by the engineering fluid mechanics can not apply under any conditions, because only in case of the gap width is less than 0.01 mm, or the gap match is less than 0.03 mm and the fluid pressure is less than 6.3MPa, the gap flow is completely laminar flowing. Beyond this range, the gap flow is changed to mixture flow combining laminar flow and turbulent flow and its flow rate is less than laminar flow, the greater the gap, the higher the pressure,the closer the turbulence. In engineering practice, most of the work pressure are on the mixed flow region. Gap value of about 0.02 mm, sealing length is greater than 20 mm is the best gap value of the matching value of water-powered rock drill percussion mechanism's friction pair, at this time the leakage flow is small, which not only guarantees the volumetric efficiency, but also take into account, the machining accuracy and processing costs. Appropriate increase in the length of seal can further increase the gap value.The principal factors influencing energy loss withing the impact mechanism was analysed and the fundamental equations of caculating energy loss caused by matching gap leakage in laminar and turbulent flows state was estabilished. The influence of losed energy transforms to new method of subsectional according seal section to analysis energy loss withing the impact mechanism has been developped. The total energy loss equations of seal section in the impact mechanism of constant pressure in pre-chamber and alternating pressure in after the cavity has been established respectively based on laminar and turbulent.The principles and formulas of a reasonable Seal gap and length are established.Appling the above-mentioned research results, successfully developed the international's first track-type SYYG65-type water-powered rock drill. The impact mechanism of constant pressure in pre-chamber and alternating pressure in after the cavity is used,and internal rotating drill rod mechanism is also used. Seal gaps and lengths of four seal sections are calculated using the total energy loss equations of turbulent flow. According using requirements of the various components, the structure, material selection and matching and anti-rust treatment methods have been designed for major parts,as piston, Cylinder block, cylinder, front and rear bearing sets, seals, and with flow-slide valve. Based on using equal acceleration models to calculate the impact performance of water-powered rock drill firstly use point transformation method calculated circulating water pressure conveniently and made a more accurate description for the dynamic process of the impact mechanism by using computer simulation program. Using self-developed experimental system carried out water-powered track-type rock drill performance testing. Test results showed that in case of water pressure 9.12 MPa, water flow 73.90L/min,the impact energy of the water-powered rock drill can achieve 85.616J, energy efficiency 20.99%, drilling speed 420mm/min,and calculation results of the main performance parameters are basically consistent to the design requirements.The research results of the present project reaches the international advanced level comparing with the similar technology.
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