Characteristics Of Small Hole Grinding For Hard And Brittle Materials

The hard and brittle materials with high performance, such as optical glass,ceramics, semiconductor, man-made crystal etc, will be involved in machining smallholes while are applied in aviation, optics, electron, automobile and military areas.Usually, high precision and roughness of holes are needed. There are also someproblems to be solved for small diameter wheel grinding processes. It is necessary toanalyze the machining characters of small diameter grinding, and then determine thestructure parameters of grinding wheel and machining parameters according todifferent hard and brittle materials.The relations between the grinding force of single grit and the machiningparameters were analyzed according to the theory of grinding geometry andmechanics. The study indicated that while small hole machined small diametergrinding wheel, the higher hardness of workpiece materials made the grinding wheelpole bend so that the actual grinding thickness reduced and the grinding force ofsingly grit decreased obviously. There was few pull-out of grits.Considering the calculating of removal rate and the relations between machiningparameters and actual grinding thickness, the effect of machining parameters toremoval rate was analyzed. Then through the calculation of total length of grindingarc, the relations between grinding arc and parameters of grinding wheel andmachining parameters were obtained. The study indicated that increasing the grindingthickness in theory, decreasing the final angle of grits pyramid and intervals betweentwo successive grits, can not only improve removal rate, but also decrease wear ofgrits and increase grinding ratio.Based on predictive modeling of plane surface roughness, this paper arranged thegrain protrusion height and their order by Gaussian distribution. According to thegrinding geometry and characters of workpiece kinematics, surface roughness ofgrinding hole was calculated in polar coordinates. The study indicated that thedifferences of grits protrudent height affected the roughness greatly. Increasing thevelocity of grinding wheel or decreasing velocity of workpiece and intervals betweentwo successive grits can reduce value of sergace...