AP&T designs, manufactures and markets automation, presses, tools and complete production lines for the sheet metal industry.
As a leading supplier of advanced sheet metal forming technologies, AP&T has validated experimental characterisation tests of a high-strength Aluminium sheet metal component formed through hot forming.
Conventional tool try-out often means many loops of die spotting, a high effort to compensate the tool surface and to rework specific areas of the tool. AP&T has estimated the average try-out time to roughly two weeks for complex tooling applications, which means a high impact on cost and lead time.
FEM sheet metal forming simulations were used to predict the forming behaviour of the sheet metal and can give a good indication of thermal distortion and springback of the final part. The accuracy of the used simulation models is defined by the degree of idealization of the applied models and the simulation input parameters.
The AP&T case study was aimed at reducing the average try-out time, and indirectly costs by 50%, by applying a simulation step into the conventional try-out process chain. A new FEM sheet forming simulation model was established, based on data obtained during the hot forming process in order to establish a digital twin, which can be used to guide the try-out of forming dies.
Step by step
Firstly, practical forming trials were carried out in an aluminium test line using a door ring test tool to measure various parameters (e.g. press kinematics, thermal behaviour, slide speed and cushion force) to be implemented in the FEM sheet forming simulation. Additionally, the tool surfaces were 3D-scanned to enable modelling of geometrical differences between the nominal tool surface and the manufactured tool.
Apart from the temperature measurement data, press kinematics parameters and 3D-scans of the tool surfaces obtained during the practical forming trials, the FEM sheet forming simulation model would be incomplete without a proper material card. For this purpose, material characterisation parameters of two aluminium grades were obtained via hot tensile tests at different temperatures and stain rates performed by FormPlanet partners.
With this material data, a FEM sheet forming simulation model based on measured process data obtained during the hot forming process was set up. To validate the model performance, the thinning and thickening behaviour of the door ring part was investigated and compared with thickness scans of the formed parts.
Conclusions of this use case indicate that FEM sheet metal forming simulations can be used to predict the forming behaviour of the sheet metal and can give a good indication of thermal distortion and thickness behaviour of the final part. The obtained material data can serve as a basis when formulating the material card in the FEM simulation setup to study the springback and virtual tool compensation.
“A reduction of one-week try-out time is expected by implementing a digital twin based on FEM sheet metal forming simulations during the tool try-out process for hot forming applications.”
Vedran Kovacevic, Research and Test Engineer, AP&T
Frictionless determination of sheet metal forming limit behaviour under temperatures up to 900ºC. These measurements are highly interesting for hot stamping processes of aluminium and steels sheets.