Pressings shape evaluation by modern contactless methods

Abstract

As part of the Industry 4.0 concept, companies are adopting new processes that utilize contactless methods to assess the shapes of pressings. Evaluating the pressings is essential due to the springback phenomena that occur after plastic deformation, which is more pronounced when high-strength steels are used in car bodies. Although photogrammetric methods based on 2D images have been used in the industry for over a decade, 3D optical scanning methods are preferred because they offer increased precision. This article evaluated cylindrical pressings made of dual-phase steel DP800 with a thickness of 1.6 mm—specifically flat-bottomed and hemispherical-bottomed cups. The shape of the pressings was determined using optical scanning with the GOM Scan 1 device alongside a photogrammetric system called ARGUS. The surfaces obtained from both methods were then compared to assess the accuracy of the scanned surface against the real surface acquired through photogrammetry. The scanned surfaces of the pressings were also used to compare the results of numerical simulations conducted in PamStamp software. In these simulations, the material was modelled using two sets of constitutive laws: the Hill48 yield law combined with the Hollomon hardening law as the first set and the Vegter Lite yield law combined with the Krupkowski hardening law as the second set. Real cups with a diameter of 50 mm were created using a deep-drawing process on the Erichsen 145-60 testing machine, starting with a blank diameter of 90 mm and lubricated with plastic foil to preserve the electrochemically etched grid. A comparison between the scanned surfaces and the real surfaces obtained through photogrammetry showed a strong correlation, validating 3D scanning as an effective method for evaluating pressing shapes. Furthermore, comparing the scanned surfaces with the results of the numerical simulations demonstrated similar findings for both sets of constitutive laws used to model the dual-phase steel in the experiments.