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The main benefit of using optimally shaped blanks in sheet metal forming is to maximize the efficiency of the forming process and, since there is no need for additional cutting operations after the finished forming operation, this leads to a substantial reduction in overall production costs. This paper presents a numerical method for optimal blank shape determination, which is suitable in various sheet metal forming applications. The optimal blank shape is determined in an iterative way so that the edge geometry of the formed product fits its reference geometry as closely as possible. The iterative process starts with the blank shape from which the product is produced with its edge fitting its reference geometry just approximately. In subsequent iterations, the blank shape is continuously improved in accordance with the developed optimisation method. In order to determine the product edge geometry resulting from the given blank shape, a computer simulation of the forming process and related springback is performed at each iteration. Since its effectiveness greatly depends on the quality and physical objectivity of the computer simulation, the developed numerical blank shape optimisation procedure has also been validated experimentally by using the forming of a product with a rather complex edge geometry as the case study.

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This paper presents a numerical method for simultaneous optimization of blank shape and forming tool geometry in three-dimensional sheet metal forming operations. The proposed iterative procedure enables the manufacturing of sheet metal products with geometry fitting within specific tolerances (surface and edge deviations less than 0.5 or 1.0 mm, respectively) that prescribe the maximum allowable deviation between the simulated and desired geometry. Moreover, the edge geometry of the product is affected by the shape of the blank and by an additional trimming phase after the forming process. The influences of sheet metal thinning, edge geometry, and springback after forming and trimming are considered throughout the blank and tool optimization process. It is demonstrated that the procedure effectively optimizes the tool and blank shape within seven iterations without unexpected convergence oscillations. Finally, the procedure thus developed is experimentally validated on an automobile product with elaborated design and geometry which prone to large springback amounts owning to complex-phase advanced high strength steel material selection.

Warpage is one of the most challenging defects occurring in plastic injection moulded parts. Various approaches to overcome this issue have been proposed in the literature, but they all provide only partial solutions to the problem. This paper proposes a new method for the compensation and minimisation of warpage. The method is based on Mould Cavity (MC) correction. In contrast to other similar methods, here the MC correction is accomplished through a direct comparison of the local deviations of the warped part's geometry to the desired geometry of the part. Modifying the MC shape accordingly yields parts with a lower shape discrepancy from the desired geometry compared to the nonadjusted shape. The key novelty of the paper is the development of software that iteratively adjusts the MC shape to minimise local deviations. In every iteration, the warped part is compared to the desired geometry and the MC geometry is adjusted accordingly. A curved thin-walled plate part case study demonstrates the method's capabilities. We show that the maximum warpage value of 0.005 mm (0.7% of the initial maximum warpage) was reached after three iterations of MC geometry correction and remained stable afterwards.