Study On Machining Mechanism And Surface Quality In Ultrasonic Vibration Grinding Of Silicon Nitride Ceramics

Over the past years, metal materials has taken the dominant position in structural materials application. With the social development and progress, many high technology fields, especially in extreme conditions, metal materials are increasingly unable to meet the actual needs. Advanced structural ceramics, with its high strength, high hardness, wear resistance, corrosion resistance and excellent low thermal conductivity, are widely used in modern social. It has become more and more important. However, due to its high hardness, brittleness, low efficiency of conventional machining method, prone to defects such as broken collapse, and high production costs, it's limited the further application of advanced structural ceramics. To solve the above problem, the author proposed using ultrasonic vibration grinding to machining silicon nitride ceramic, analyzed of the effect of ultrasonic vibration grinding on the machining mechanism and surface quality.The study of removal mechanism of silicon nitride ceramic materials is the premise of its application. The trajectory of ultrasonic vibration grinding processing is different from conventional processing, so its necessary to make a research on ultrasonic vibration grinding trajectory to analyze the effect of the new trajectory. In this paper, the author maked use of indentation fracture analyzed material removal mechanism, with the effect of conventional grinding process mechanics, analysis the trajectory of grit on different tool positions removal material in ultrasonic grinding. The results showed that ultrasonic grinding tend to reduce surface damage and surface roughness, also reduce the processing temperature and improve processing efficiency.Because of the complexity of the grinding process, indentation experiments were used to analyze the removal process. In order to get a comprehensive analysis of the stress and strain situation of silicon nitride ceramics when under pressure head, and to analysis the impact of indentation process that caused by ultrasonic vibration, this paper did the simulation and indentation experiments analysis. From the contrast of ultrasonic vibration indentation and the general indentation, this paper analyzed the impact of ultrasonic vibration worked on the processing. Simulation results show that ultrasonic vibration can reduce the average power of ceramic materials and the impact region of pressure head. Thus reducing the probability of the median cracks and reducing the depth of metamorphic layer.Based on the above analysis, this paper carried the silicon nitride ceramic ultrasonic vibration grinding processing experiment, verified the effect of ultrasonic vibration. orthogonal experiment analyzed the influence that technology worked on surface quality. Finally we get that the degree of influence on surface roughness are in turn reduced by spindle speed, feed speed, grinding depth and vibration amplitude.