Research On Lapping Mechanism And Process In Mass Production For Precision Si3N4 Ceramic Ball

Silicon nitride(Si3N4)ceramic ball has been recognized as one of the most ideal materials for manufacturing precision rolling bearing because of its excellent comprehensive performance.Qualified rate for finished product was relatively low.And batch consistency was poor in the traditional lapping method.So it was difficult to get precision Si3N4 ceramic balls in mass production.In this paper,the research was put for the suitable lapping process in the experiments for precision Si3N4 ceramic ball.And the new lapping machine for batch lapping was developed on the basis of the traditional lapping equipment.This article main research work includes several aspects:1.The theory research for sphericity and ball diameter tend to consistency in the lapping process of ceramic ball was analyzed.The surface defects in ceramic ball were statistically classified and analyzed its causes.CMP was used for improving surface defects of ceramic balls in the experiment.The precision balls with super smooth surface were obtained.2.The removal form for lapping process of Si3N4 ceramic ball was analyzed.It is concluded that remove form is up to inherent attribute of ceramic ball and lapping process parameters.The lapping process removal model for ceramic ball was set up based on two-three body model.The orthogonal experiment was operated by using the taguchi method for studying the influence to Si3N4 ceramic material remove by pressure lapping speed and grinding fluid concentration.The single factor experiment method for Si3N4 ceramic ball grinding process of material removal wear experiment was operated to get remove equation by multiple linear,and provided theoretical basis for development of suitable lapping process parameters for mass production.3.The batch lapping experiments for Si3N4 ceramic ball was operated.The sphericity and surface roughness,material removal rate,vibration value of the results were analysed in different lapping stage.The surface quality was evaluated on the Si3N4 ball,the sphericity,surface roughness and vibration value of the finished Si3N4 balls were tested.The experimental results indicate that sphericity,surface roughness and vibration value were lower than 0.09?m,5nm and 26dB respectively.And the Si3N4 balls at the G5 level in mass production were obtained.The yield above G5 level for precision ball reached 50%compared with the traditional process of yield 30%.The new process was more suitable for precision ceramic ball mass lapping processing.4.The existing problems in the traditional lapping equipment were summarized.And the lapping machine with eccentric automatic pressure for mass production was developed.This new equipment can control loading pressure and lapping speed under 4%for lapping processing.The batch lapping experiments for Si3N4 ceramic ball was operated.The experimental results indicate that sphericity,surface roughness and vibration value were lower than 0.062?m,3nm and 24 dB respectively.The yield above G3 level for precision ball reached 30%.The yield above G5 level for precision ball reached 60%.The new equipment is more suitable for precision ceramic ball mass lapping processing.