A general framework for grinding process simulation

This thesis is a collaboration between Polytechnic university of Milan and CNR. The aim of this work is introduce a general framework conceived for providing a time-domain simulation engine based on a Dexel representation of wheel and work piece, capable to “host” all the semi-empirical models existing in literature. When considering the mechanics of grinding, several physical phenomena have to be modelled, each one having effect on the resulting grinding forces, wheel and work piece geometry. Depending on the analysed problem, some dependencies can be neglected to privilege some aspects instead of others. Nevertheless, all models essentially start considering wheel-work piece engagement and the corresponding material removal (both wheel and work piece side), deriving the forces by means of energy balances and/or shear mechanics. The overall grinding force is the result of the integration of the force contributions associated to the local removal along wheel ,work piece engagement arc. Focusing on the approaches based on wheel and work piece discretization, it can be noted that the different force and wear models relies on a common “geometrical” kernel devoted to the computation of wheel-work piece engagement and the consequent wheel wear and work piece material removal. Thus, a meta-model can be identified, constituted by a set of fundamental relationships that receive in input the reduced set of “geometrical” quantities provided by the simulation engine, yielding in output the grinding force and the updated wheel and work piece geometry. In particular, the fundamental relationship can be represented by interpolation basis, namely, response surfaces (RS) that can be extracted from both analytical expressions and empirical lock-up tables retrievable in literature. A cascade approach is adopted to solve for forces and displacements the DAEs set describing the dynamic interactions between wheel and work piece, whereas all the algebraic relationships pertaining to the various specific models are solved in a pre-processing phase, yielding a set of response surfaces that are queried during time integration. Finally, the meta-model framework is instantiated for a model of traverse roll grinding with force-dependent wheel wear.