Theoretical Study On High Efficiency And Ductile Regime Lapping Of Semi-fixed Abrasive Plate

To attain machining advanced ceramic with the performance of high efficiency, high precision and low surface damage, a semi-fixed abrasive lapping technique is proposed because of its ’trap’ effect. This technique could reduce change of cutting depth owing to the difference of grain size and protrusion height of surface abrasive of grinding plate. And near equal-cutting-depth processing is realized. So the semi-fixed abrasive lapping technique can achieve ductile mode machining efficiently for advanced ceramic. For characteristics and machining performance of semi-fixed abrasive lapping, this paper relates to the following studies:The model of cutting depth distribution of grains of semi-fixed abrasive plate (SFAP) was proposed and established. The shape of the abrasive grit has been discussed, and the abrasive grit shape model of SFAP was simplified. The displacement of abrasive grit was analyzed during processing. The normal force analysis to single grit was set up by using elastic-plastic mechanics, and the relationship between cutting depth and the grain size, the displacement, Modulus, hardness of single grit was obtained. The grain size of SFAP is obeyed log-normal distribution. By using probability and statistics, the model of cutting depth distribution of grains of SFAP was obtained. A theoretical foundation of optimization and evaluation of semi-fixed abrasive machining was set up.On the basis of the model of the abrasive grains cutting depth distribution of SFAP, the influence of SFAP properties (sizes of abrasive grains, concentration of SFB bond), processing technology (processing load) and other parameters on the abrasive grains cutting depth distribution was analyzed by using computer simulation. The results showed that the abrasive grains cutting depth distribution of SFAP of simulation was basically consistent with that of experiment. There were some deviations with the model simulation between the experimental results. The results also showed that the abrasive grains size of SFAP was most powerful factor on the abrasive grains cutting depth distribution. For 1000#SiC SFAP, the elastic modulus of plate bond has greater effect on the consistency of the abrasive grains cutting depth distribution (Standard deviation). And processing load has greater effect on the average cutting depth (mathematical expectation).The processing technology of semi-fixed abrasive machining for single crystal silicon was designed and optimized. Firstly, the ductile-brittle critical depth of single crystal silicon was investigated by small slope lapping. This method was close to the actual processing of circumstances to study the ductile-brittle critical depth of single crystal silicon. The ductile-brittle transition characteristics of single crystal silicon were investigated by optical interferometric profiler Wyko NT9800. The results showed the critical depth of single crystal silicon was related to abrasive tip blade radius. The abrasive edge radius size distribution also had a certain relationship with the abrasive grains size, but the relationship was more complex. There was little difference between crystal plane (111) and crystal plane (111) in single crystal silicon critical depth. Secondly, the plates with different bonding concentration were compared in surface roughness and material removal rate. The SFB bond SFAP with concentration of 35 wt% was the best plate, and high efficiency ductile regime lapping for single crystal silicon was designed. Compare with the same processing parameters of loose abrasive machining, the surface quality of single crystal silicon and processing time of SFAP lapping were significantly better than those of loose abrasive machining. It proves the advantages of semi-fixed abrasive machining about precision and high efficiency.In this dissertation, cutting depth distribution of grains of SFAP in processing was studied. Research showed that single crystal silicon could be machined in high efficiency and ductile regime mode, if the abrasive grains size of SFAP, concentration of SFB bond and processing load were designed appropriately. These were benefits to design, manufacture and application of SFAP.