Automatic Tool Selection and Dimensional Accuracy Verification in Computer Aided Process Planning for Sheet Metal Bending (Automatische gereedschapselectie en dimensionele nauwkeurigheidsverificatie voor computergesteunde werkvoorbereiding voor het buigproces)
Automatic Tool Selection and Dimensional Accuracy Verification in Computer Aided Process Planning for Sheet Metal Bending
Nguyen, Thi Hong Minh; M0231210
Sheet metal products are widely used in various industries nowadays. Among those, bent parts are made by performing linear bends on the sheet metal blanks prepared according to the unfolding of the corresponding designs. Computer aided process planning (CAPP) for bent parts consists of closely related tasks. In this context, the aspects of tool selection and dimensional accuracy verification have been tackled in this study. Due to the industrial requirements for part complexity and tool variety, simple mapping compatible and collision-free tools to bend lines merely based on part descriptions is not plausible. Meanwhile, the interrelation between tool selection and bend sequencing makes automated tool selection a combinatorial problem. The current research has resulted in a proactive strategy to downscale the problem complexity. Tools are firstly preselected based on the collision prone details obtained from the analysis of part geometries, and secondly refined according to the collisions detected while planning for abend sequence. Moreover, a generic approach founded on a set of rules is proposed for individual tool selections by evaluating the encountered collision scenarios. Besides, three complementary strategies for optimising the tool collection selected for a part have been worked out by considering production planning requirements. Overall, a tool selection methodology has been developed as an integral part of CAPP to obtain a feasible and well-optimised tool set for part production. The methodology hasbeen partially implemented in an industrial software package that delivers feasible results within a limited time span. Once a process plan is confirmed with a collision free bend sequence and an appropriate tool assignment, its compatibility with the tolerance plan imposed on the part should be verified. In the last part of this study, together with the insight of the sources of errors, an analytical stochastic model has been established for an efficient estimation of the distributions of the resulting global dimensions once the bend sequence and the distributions of the elementary errors are known. Therefore, the error stack-up and the stochasticity of the process have been incorporated with economic time complexity.