Efficient Simulation and Optimization for Tandem Press Lines
Sammanfattning: Today, simulation is needed as one of the tools for optimum utilization of a press line.Utilization includes: high throughput, minimum ware of the line and high quality. Highquality includes quality of the produced parts, quality of the stamping dies and quality of thetooling manufactured. In order to perform efficient geometrical simulation and virtualcommissioning in stamping, two main fields are investigated namely simulation time andoptimization time. Thus, reducing computation time is the main theme of this thesis. Anefficient press line simulation model is built and verified, resulting in reduced simulationbuilding time due to the modularization of the model.To reduce simulation time, collision detection time is reduced by a method based on 3Dto 2D geometrical collision detection. The method is based on pre-calculation of all collisionpoints in the environment of interest, and then using a simplified collision detection model ina simulation based optimization. This is less resource consuming than collision checking theoriginal 3D objects for all optimization evaluations. The suggested approach reduces thecollision detection from a 3D to a 2D problem, where collision between simplified butmoving curves is used in the repeated simulation for optimization. This collision detectionapproach, together with a simplified implementation of the control code, results in ~200 timesreduction of the computation time, compared to the original simulation based on standard 3Dcollision detection.The variable parameters in a press line exceed 100, resulting in time/computationallydemanding computations. There is also a need of fast optimizations for die design, line tryoutand ramp-up. Since the number of evaluations grows exponentially with the number ofdimensions in an optimization problem, optimization time is reduced by a decompositionstrategy aiming at dimension reduction. Two simulation/optimization strategies were chosenand tested to decrease calculations. The presented results mean that simulation and virtualcommissioning can be performed not only for press stations but also for complete press lines,where the complexity increases linearly with the number of stations in the line.KEYWORDS: Press Line Simulation, Simulation based optimization, Virtual manufacturing,Virtual commissioning, Parameter tuning, Optimization strategies.
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