考慮磨粒與振動變異效應之表面粗糙度模式建立

By combining the kinematic grit and spindle vibration effects, an analytical ground surface roughness model representing their individual effects on the ground surface was developed. In this model, the surface profile is treated as the superposition of variances of the kinematic grit and vibration profiles. By summing the variance of the two profiles, the root-mean-square ground surface roughness can be estimated. The transmitting factor, which defines the amount of power transmitted from spindle vibration to the ground surface, was derived from the dynamic grinding system and is related to the stiffness of the process, namely the workpiece cutting stiffness and wheel contact stiffness. An experimental procedure for identifying the stiffness in the process was also developed. Due to its analytical nature, the model estimates the ground surface roughness as well as allowing for the analysis of the contribution and effects of the grinding conditions, machine vibration and stiffness within the process. Procedures for identifying the process parameters were developed and a series of experiments with varying parameters were performed in order to validate the model. Discussions regarding the grinding conditions for the surface roughness based on experimental and model analysis results are presented. The model predictions and experimental results support the finding that a greater grinding depth and width increases the grinding force and hence deteriorates the ground surface. Furthermore, although a greater feed of the workpiece results in a larger grinding force and spindle vibrations, it also increases the cutting stiffness and thus reduces the transmitting factor of the spindle vibration, diminishing its adverse effects on the ground surface roughness.