Technique to Optimize a Combination of Kraftforming and Rollforming for Fabrication of Rounded Metal Building Envelope Components

This paper presents an approach to fabricating rounded metal components used in architectural building envelopes, combining traditional metalworking techniques with advanced digital modelling. It emphasizes a refined method for crafting double-curved metal profiles that can enhance contemporary architectural designs, applicable in roofing and facades, for example as window and ledge sheets and as wall or parapet coverings. Traditionally, producing unique rounded metal profiles depended heavily on craftsmanship using standard tools. Market demand for larger metal profiles necessitated an optimized process, facilitated by electrically motorized bead and flanging machines, fitted with custom-made roller sets, that bend edges precisely. The kraftformer machine, equipped with various forming tools, supports manual cold forming, requiring skilled operators to achieve flawless surfaces. A key to advancement was the digital documentation of the entire metal forming process through photogrammetry on reference sheets. This involved multiple trials and detailed measurements to ensure accuracy, supported by specialized software for analysing material deformation throughout the forming stages. Within the project a comprehensive parametric model was developed for virtually simulating the material cutting and the forming processes. This model handles variables like radii, length, height, material thickness, and rollforming radii, predicting and visualizing geometric forms while analysing material properties via a finite element mesh. This simulation is pivotal in optimizing roll-forming and kraftforming stages, leading to the development of specialized tool heads and roller sets that achieve higher precision. The research resulted in improved production capabilities for rounded metal profiles with greater dimensions. Application of these methods to the fabrication of parts for a real-world construction project in Switzerland highlights their practical value and architectural significance. In conclusion, the paper showcases the successful integration of traditional skills and modern digital methods in metalworking, leading to more precise and efficient construction processes in architectural fabrication.