As part of a research project (CFKFormTool), Fraunhofer IPA and the company Fichtner und Schicht have jointly developed a forming tool with which it is possible to produce any double-curved components. The process was supported by a HORST industrial robot, which enables automated adjustment of the mold. The process enables fiber composite components to be produced economically in small batches.
Fiber-reinforced plastics offer huge potential for lightweight construction. They are used in areas such as aerospace engineering, the automotive industry and medical technology. However, molds are required for their production. These molds are rigid, can only be used for a specific component geometry and are usually very expensive. The reason for this is that they have to be milled from solid blocks. For prototypes or small series in particular, this means that the lightweight properties of fiber-reinforced plastic cannot be used economically.
Another problem is the large amount of material required for the tools. Although aluminum molds, for example, are recyclable, large amounts of energy are required to melt them down.
The aim of the CFKFormToolwares project is to develop a forming tool that can be brought into any shape on the basis of CAD data. The mold is set automatically by a HORST industrial robot. For this purpose, the forming tool consists of a large number of height-adjustable pins. They serve as the basis for the mold. A film is pulled over the pins onto which the components are laminated.
In several development steps, both the setting accuracy of the pins and the molding accuracy of the film were improved. The crucial points here were, on the one hand, the precise recording of the actual height during the setting process and, on the other hand, the development of a film that interpolates the discrete pin heights to create a surface that is as uniform as possible.
At the end of the project, double-curved surfaces with radii of curvature of less than 600 millimetres could be mapped. It takes less than 30 minutes to fully adapt the geometry.
Thanks for the support of Fraunhofer IPA. This article was first published, in a slightly modified form, at interaktiv.ipa.fraunhofer.de/leichtbau-und-additive-verfahren/adaptive-formwerkzeuge-senken-kosten-in-der-cfk-herstellung/