Part surface roughness modeling and process optimal control of cylindrical grinding

The grinding process is an economical operation to obtain high quality products. Purely empirical models have been used extensively in grinding to determine the machine set-up parameters subject to certain quality constraints. Either physical models or a combination of physical and empirical models is desired in order to improve the reliability and quality of predictions by directly improving process control and optimization.; A grinding process model based on a probabilistic analysis of the chip thickness is presented. The normal force, the tangential force and the grinding power were predicted and validated using empirical data for both surface and cylindrical grinding. Furthermore, the predicted chip thickness is compared to experimental grinding chips to show the validity of the probabilistic analysis. The model includes tool properties (static grain density and grain geometry), material properties (grain interface friction and material hardness), and grinding kinematic conditions (depth of cut and wheel and work piece tangential velocity). The dynamic effects generated by the local grain force and by the total grinding force are included analytically in the model. A surface roughness model based on the predicted chip thickness is formulated and validated with empirical data. From this model, predictions of the surface roughness with respect to the changes in grinding conditions are presented.; A hybrid grinding cycle is proposed by combining power control during the stock removal stage and velocity control during the final stage. The grinding power model and the surface roughness model of the part are used to simulate the process and to find the optimal settings for the cycle. The desired grinding power for stock removal was subject to maximum machine capabilities and work piece burn. The feed of the final stage was found based on the final part requirements such as surface roughness and the theoretical out-of-roundness. This grinding cycle was implemented and tested in an open architecture machine.