A computer-aided design module to analyze manufacturing configurations of bent and hydroformed tubes

This paper presents a computer-aided design (CAD) module able to analyze different manufacturing configurations of tubes used in mechanical assemblies, such as exhaust system manifolds. It can be included in the knowledge-based expert system category and has been implemented into a CAD platform as a dedicated module able to take into account manufacturing requirements related to tube bending, hydroforming, and cutting. The expert's knowledge, in terms of set of rules and criteria, has been implemented by means of the automation tools of CATIAV5R10 according to the socalled methodological formal approach. The resulting module is able to join different tubes starting from their geometrical models, obtaining a set of manufacturing alternatives. Each of them is verified with respect to collisions with a bending machine and also in terms of hydroforming process feasibility. Only those solutions that satisfy these checks are accepted as feasible and ranked according to three evaluation criteria related to manufacturing cost and easiness. The system is completely automatic and able to analyze more than 100 different configurations in <10 min. The feasible solutions are saved as CAD model to allow FEA of hydroforming and other possible CAE activities. Unfeasible solutions are deleted but reported and documented in a log file. The feasible solution rank is given in a table and has been developed according to a multicriteria approach to make optimal solution detection easier. The proposed test case aims to show and discuss these capabilities. By this module, two or more components of the exhaust system manifold can be manufactured in one stroke as a single component, starting from the same pipe and next trimmed to obtain the desired final parts. This capability can be used to reduce scraps and improve cycle time of the manufac-turing process. Copyright © 2007 by ASME.