Simulation methodologies within virtual manufacturing applied on mechanical cutting

Detta är en avhandling från Luleå : Luleå tekniska universitet

Sammanfattning: Virtual manufacturing, that is, simulation of welding, heat treatment, cutting and other manufacturing processes is becoming more and more used as a tool for prediction of material- and mechanical properties in modern industry. By simulations we refer in this case to FE-simulations of the thermo-mechanical effect of the manufacturing process on the component in question. Despite the fact that simulations are becoming more widely used, there is a lack of integration of simulations of manufacturing processes in the sense that most work focuses on an individual process being simulated. It is only when a complete chain of manufacturing processes can be simulated the real benefits, of using virtual manufacturing as a tool within product- and process development, will become evident. The thesis focuses on simulation methodologies within virtual manufacturing, and specifically methodologies for cutting simulations. Simulation of mechanical cutting has been identified as a key area where computational difficulties arise when attempting to simulate a sequence of manufacturing processes involving some form of cutting operation. A distortion problem during manufacture of a shaft front to a RM12 engine has been analysed. At one time, distortions aroused during the later stages of the cutting sequences involved in the manufacture of the shaft front. The cooling from solution heat treatment temperature and the cutting sequence was to be simulated. The result from the cooling sequence however show that the cooling does not cause residual stresses that in turn cause distortions in subsequent cutting sequences, and hence only results from the cooling procedure is presented. A test case was constructed to ensure that residual stresses would be present causing distortions during subsequent cutting. The experimental set- up with both a forming operation and subsequent cutting is used as a validation tool for the simulation of cutting using an element deactivation technique. The results show that the technique developed can be a useful tool for simulation of mechanical cutting when interested in distortions on component level. Another necessity when performing analyses of a sequence of manufacturing processes is a system for exchange of Engineering Analysis Data (EAD) between each of the simulations. Further, a system for handling the increasing amount of EAD in the product- and process development process is also needed. Most engineering software is today used to solve engineering problems within a single, limited domain. Efforts have been made to develop standardised formats such as IGES and STEP for EAD exchange both within and across domains. However, by limited implementation in commercial software the user is often forced to either program translation routines that enables data sharing or even recreate meshes, boundary conditions etc. A system has been developed that supports the management of computer-based simulation information. The paper describes how information modelling and database technologies can bring new dimensions to the effective use of engineering simulations in product- and process development.

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