Research On Grinding Mechanism And Quality Control In Machining High-Hardness Spherical Surface

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.