Optimal module selection for preliminary design of reconfigurable machine tools

Presented in this paper is a feature-based method for selecting an optimal (minimum yet sufficient) set of modules necessary to form a reconfigurable machine tool for producing a part family. This method consists of two parts. In the first part, a feature-module database is created to form a selection space, where the machinable geometric features identified in STEP are defined as functional requirements (FR's) and the structural component modules derived from the conventional machine tools as design parameters (DP's). An inner FR-to-DP mapping mechanism within the database is based on the "Membership Grade Matrix, " which defines metrics to quantify the degree of association between a FR and a DR Within the confines of the selection space built upon this FR-DP database, the second part of the method involves a two-step procedure for module selection. The first step is to select the modules from this space to construct all the required individual configurations of the reconfigurable machine tool. The second step is to maximize the number of common modules among the originally selected modules through re-selection. A case study on designing a reconfigurable machine tool dedicated to a given family of die molds is conducted and discussed.