【作者】 许开州；

【导师】 胡德金；

【作者基本信息】 上海交通大学 ， 机械制造及自动化， 2011， 博士

【摘要】 当前,高硬度金属基材料(如WC-Co,Ni60 ,STL20)的发展很快,它们具有耐高温、耐高压、耐磨损、抗热冲击、抗热腐蚀等特性,并在钢铁冶炼、石油化工、核电等重大工程项目中发挥着越来越大的作用。这类材料在平面磨削加工的研究已经开展,但在球面磨削上研究工作还较少,众多基础问题有待探明。虽然在磨削机理研究上球面磨削可以部分借鉴平面磨削的研究成果,但在磨削工艺基础理论上球面磨削特点鲜明,在实际磨削过程中发现越来越多亟待研究的问题。本文针对高硬度材料在球面磨削中以何种方式去除以及球面磨削质量如何提高此两大问题在高硬度球面磨削机理和磨削质量控制上展开了系统的研究。本文首先针对高硬度球面加工的两大难点,即工件表面硬度高(HRC≥70)材料难以去除以及形状精度要求高等,开发了一种新型的高硬度回转球面精密磨削装备,该装备在保证被加工球面精度和表面粗糙度的前提下,可用一种直径规格的砂轮磨具实现不同直径规格球面的精密磨削加工。从利于实验观察和测量的角度出发,采用杯形砂轮平面封闭分布式磨削来揭示球面磨削机理。首先系统的研究了高硬度材料封闭分布式磨削的磨削力。构造了表征封闭分布式磨削力的参数模型,包括有效磨削宽度、有效磨削面积、动态有效磨粒数等,研究了磨削加工参数对单位面积磨削力、单颗粒磨削力和磨削分力比的影响规律,并通过实验验证了这些模型的准确性。其次以磨削力的实验结果及所建立的理论模型为重要依据,结合工件磨削表面微观形貌,揭示了高硬度材料的去除机理。研究了杯形砂轮封闭分布式磨削方式下磨削加工参数对材料表面粗糙度的影响规律,在此基础上,结合球面磨削加工的特点,提出降低球面磨削表面粗糙度的方案。首先基于球面磨削轨迹成型原理,从磨头转速和主轴转速出发,提出了磨削效率、阻滞轨迹封闭相位角、最小加工次数等衡量指标,逐次修正选择策略,提高迹线密度和分布均匀性;其次在综合考虑回转工作台摆动速度、磨削深度、磨头转速和主轴转速的基础上,建立了vogl快速BP网络模型,构造正交试验表,结合小步长算法,进一步优化工艺参数,降低球面粗糙度。更多还原

【Abstract】 Currently, there is a booming development of high hardness coating materials with metal substrate, such as WC-Co, Ni60 and STL20, there are of high temperature resistance, high pressure resistance,wear resistance, thermal shock resistance and thermal corrosion resistance, and they play an important role in large-scale engineering projects such as steel-smelting, petrochemical industry and nuclear power. Research on such coating material is on the way in plane flied while not in sphere flied, spherical grinding mechanism can refer to that of plane grinding partly, but, as a unique curved surface, there are more and more problems that urgently to be solved. Therefore, in this dissertation, grinding mechanism and grinding quality control in machining spherical surface are researched.According to two difficulties in spherical surface machining, that is high hardness of workpiece surface and high form accuracy, a new high hardness spherical surface grinder is built, different diameter sphere can be grinded by one type wheel, and their sphericity and surface toughness can be guaranteed.In favor of experimental observation and measurement, the closed and distributed grinding was used to reveal the grinding mechanism. Firstly, the grinding force was researched in detail, grinding parameters, including effective grinding width, effective grinding area, number of effective dynamic grains and grinding force etc, were constructed, secondly, the characteristics of the grinding force was analyzed and the influence of grinding parameters (including the grinding depth, feeding speed of workpiece , grain size and the type of caking agent ) on the grinding force( including the grinding force of elemental area and each grain of the wheel ) and the grinding force ratio were analyzed, finally, based on the microscopic topography analysis and the experiment results, the mechanism of high hardness WC-Co material is revealed.The influence of grinding parameters (including the grinding depth, feeding speed of workpiece , grain size and the type of caking agent ) on the surface toughness( including the grinding force of elemental area and each grain of the wheel ) was analyzed, and according to the processing characteristic, a method to reduce surface toughness was proposed. On the basis of track molding theory, according to wheel speed and main spindle speed, grinding efficiency, phase angle to retard trajectory close, minimum machining time were presented. Then, take into account work table rotational speed and grinding depth, an improved vogl fast BP network model was built, orthogonal experimental table was designed, combining with small step search method and optimization of technology parameters, spherical surface roughness is improved finally.更多还原