【作者】 周梓荣；

【导师】 李夕兵； 刘迎春；

【作者基本信息】 中南大学 ， 采矿工程， 2010， 博士

【摘要】 纯水清洁无毒、使用安全、价格低廉,是一种绿色环保的传动介质。水压传动技术已经成功地应用于食品、采煤、采石、冶金、海洋开发、制药等行业。近年来,随着水压传动系统关键元件——水压柱塞泵和水压控制阀的研究取得长足进步,水压传动的实用范围也迅速扩大。在采矿业,随着开采深度的不断增加,尤其是在硬岩金属矿深井采掘中,需从地面或高中段引入清洁水去为作业面降尘降温。如能充分兼用这部分水因落差产生的水力势能去驱动凿岩机及其它作业机械,则可大幅度降低生产成本,节省能量消耗。而水压凿岩机及其核心部件——水压冲击机构则为此项技术发展的关键。水压凿岩机冲击机构承受高频冲击载荷,不仅要解决与水压柱塞泵等同样面临的因水粘性低带来的泄漏与润滑性极差的问题,还要研究能承受冲击载荷作用、耐腐蚀、耐摩擦磨损的冲击活塞—缸体(套)及密封部件等材料。本文选定水压冲击机构两个最主要的关键技术——冲击摩擦副的材料配对及泄漏控制开展了研究工作。在分析了水压冲击机构运动和受力状况的基础上,提出了摩擦副材料的选择及配对原则,引入聚合物材料与不锈钢配对作为水压冲击机构摩擦副新的配对方案。根据水压冲击机构工作条件,研制了3种配方的碳纤维增强聚四氟乙烯(PTFE)复合材料,利用环块摩擦试验机、金相和扫描电子显微镜以及散能分光计等设备对3种复合材料与不锈钢在水润滑条件下的摩擦学特性进行了试验研究,分析了载荷、对磨时间、碳纤维含量、二硫化钼含量、铜粉含量等对摩擦系数和PTFE磨损量的影响。研究发现,在水润滑下,碳纤维含量为15%的PTFE复合材料与高温氮化处理的0Cr17Ni4Cu4Nb在载荷200N、滑动速度5m/s下的摩擦系数仅为0.011,居国内同类材料已见报道之最低位。试验前15min摩擦系数随载荷的增加有所下降,15min后其摩擦系数基本稳定在0.011-0.014,说明15分钟后在不锈钢表面上已经覆盖了碳纤维,两者之间的摩擦基本变成了碳—碳之间的摩擦,因而摩擦系数相当低。碳纤维PTFE复合材料的主要磨损机理是疲劳磨损,碳纤维含量越高,摩擦系数就越低；载荷从100N到250N,磨损量随载荷的增加而降低,从250N开始磨损量随载荷的增加而增加。采用线性极化法,对3种不锈钢材料经热处理或高温氮化处理后的防锈性能进行了研究,并和未经处理的不锈钢进行了电化学腐蚀对比试验。结果表明,不锈钢经热处理或高温氮化处理后防锈性能有所下降；经热处理或固溶化处理后的不锈钢材料中,316L和2205的防锈性能要好于17-4PH。试验了零件表面盐浴复合氮处理、热喷涂纳米陶瓷、镀硬铬等表面防锈方法。试验结果表明：盐浴复合氮化处理技术可以满足凿岩机缸体、连接体、机头等非直接摩擦件的防腐蚀要求,但不能作为承受强烈冲击载荷作用的冲击活塞及配对零件的表面防锈处理方法；通过采取某些改进措施保证镀铬层的结合力和致密性,表面镀硬铬防锈可以满足中低冲击能(≤120J)凿岩机冲击活塞的处理要求。压力水在环形间隙中流动的理论分析和试验研究以及基于AMESim软件进行的仿真分析表明：工程流体力学中提出的环形缝隙中的层流流量计算公式并不是任何条件下都适用,只有配合间隙小于0.01mm,或配合间隙小于0.03 mm而流体压力小于6.3MPa,才是完全的层流流动。超出此范围即为层流与紊流的混合流动,其流量要小于层流流量,间隙越大,压力越高,越接近紊流。压力大于10.0MPa,或间隙大于0.05 mm时基本接近于紊流。在工程实际中,大部分的工作状态都为混合流或紊流。间隙值在0.02 mm左右、密封长度大于20mm是水压元件及凿岩机冲击机构摩擦副配合的最佳间隙值,此时泄漏流量较小,既保证了容积效率,又兼顾了机械加工精度和加工成本。适当增加密封长度可以进一步增大间隙值。在此基础上,分析了影响冲击机构内部能量损失的主要因素,建立了层流和紊流状态下配合间隙中泄漏引起的能量损失基本方程；分析了由于能量损失转变为热量对流体温度和粘度变化的影响；提出了按密封段分段法计算活塞一个冲击运动周期内内部能量损失的新方法,并分别建立了前腔常压、后腔交变压力的单面回油型冲击机构在层流和紊流状况下各密封段的总能量损失方程。提出了最小允许间隙的确定准则,建立了最大间隙与合理密封长度的计算公式和控制范围。应用上述研究成果,研制成功了国际上第一台SYYG65型导轨式水压凿岩机。该机采用前腔常压、后腔交变压力的单面回油型冲击机构和内回转转钎机构,最高工作压力10MPa,使用按分段法建立的基于紊流流动理论的内部能量损失方程对活塞与前后支承套、缸套之间的配合间隙大小和密封长度进行了设计计算,对活塞、缸体、缸套、前后支承套、密封件及配流滑阀等主要零部件的结构、材料选用及配对和防锈处理方法等进行了分析和设计。在运用等加速模型对凿岩机冲击性能进行计算的基础上,首次运用点变换方法对循环中的水压力作功简便地进行了计算,并对冲击机构的动力过程采用计算机模拟程序作出了更加精确的描述。利用自行研制的国内首套水力凿岩实验系统开展了导轨式水压凿岩机的性能测试工作。试验结果表明：在水压为9.12 MPa,流量为73.90L／min时,凿岩机冲击能达到85.616J,能量利用率为20.99%,和主要性能参数的计算结果基本一致,达到了设计要求。该水压凿岩机在9.124MPa时的最大钻进速度449mm／min,超过了加拿大水压凿岩机试验时13MPa压力时的钻进速度(420mm／min).更多还原

【Abstract】 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.更多还原