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A concurrent approach to automated manufacturing process planning
textWith the increasing demand of fast-paced and hybrid manufacturing processes in modern industry, it is desirable to expedite the iterations between design and manufacturing through intelligent computational techniques. In this research, we propose a concurrent approach of this kind to streamline the design and manufacturing processes. With this approach, a CAD design is automatically analyzed in terms of its manufacturability in the early design stage. If the part is manufacturable, a set of process plans optimized in time, cost, fixture quality and tolerance satisfaction are reported in real time. If the part is not manufacturable, the potential design changes are provided for better manufacturing. In the approach, the geometric information of 3D models and the empirical knowledge in manufacturing processes, fixtures, and tolerances are combined and encapsulated into a graph-grammar based reasoning. The reasoning systematically extracts meaningful manufacturing details that later constitute complete process plans for any given solid model. The plans are then evaluated and optimized using a specially designed multi-objective best first search technique. The complete approach enables a concurrent and efficient manufacturability analysis tool that closely resembles real manufacturing planning practice. Numerous case studies with real engineering parts are presented to characterize the novelty and contributions of this approach. The optimality of the suggested plans is verified through computational comparisons, and the practicality of the plans is validated with hands-on implementations on the shop floor.Mechanical Engineerin
A stochastic concept for the optimization of manufacturing tolerances in computer aided process plan simulation
International audienceIn order to integrate tolerance synthesis for manufacturing dimensions in CAPP systems, an automated process plan simulation module has previously been developed. This module permits the verification of the manufacturing pre-projects and the optimization of the manufacturing dimensions. The module used an optimization procedure which was realized through an equal distribution of the excess tolerance which is that of the design functional requirement. However in reality, this distribution should take into account the stochastic aspects of the dispersions and the complexity or cost of the manufacturing dimensions. In the present work, in order to overcome these drawbacks, a statistical and cost based tolerance synthesis model has been developed. It is shown that this model performs an objective and global distribution of the residual (excess) tolerances of the design functional dimensions on all the manufacturing dimensions of the process plan. The dispersions method is used in the modelling process to determine the variables of the objective function and to automatically extract the manufacturing tolerance chains. These chains are then used to construct the functional constraints of the optimization model. The whole process has been programmed as an automated tolerancing tool for manufacture and validated for several examples