Mechanical modelling of micro-scale abrasion in superfinish belt grinding

In synchronized transmission, the shift lever force and corresponding shiftability are the most important design considerations. The present paper introduces an engineering attempt to rigorously model a synchronizing functional surface (cone surface of idler gear) according to its finish specifications. The virtual input surface is generated by an original fractal function, which reproduces the surface “signature” due to the wheel grinding process. To model the subsequent superfinishing operation by belt finishing process, which uses a soft-coated belt as a tool, an algorithm simulating the abrasive polishing conditions is especially developed and applied to rework the initial fractal surface. The basic idea of this model is that the higher the height of a peak of the profile, the lower its probability of resistance during an abrasion cycle. The belt finishing process is hence modeled by five parameters: two parameters that characterize the initial surface (fractal dimension and range amplitude) and three parameters describing the abrasion polishing process (probability of resistance, wear volume and the number of abrasion cycles). In order to ascertain that the component will be manufactured to the required specifications, the model's parameters have to be determined. For this goal, a functional model with an optimization scheme is created. This simulation provides the morphology of the initial surface and how to cope with the superfinishing process to obtain the functionality of the surface. An elevated initial roughness is required from which slow erosion is proceeded to erode peaks and conserve some valleys of the initial profile (lubricant tanks). Finally, it is shown that automotive designers impose morphological specifications obtained by the belt grinding process to prevent scuffing of the motor parts.