Researchers from the Laboratory for Forming (LAP) and the Laboratory for Handling, Assembly and Pneumatics (LASIM) have published their latest research findings in the renowned Elsevier journal Materials & Design (IF = 7.9). The article presents the development of an innovative hybrid machine based on a servo-hydraulic press that overcomes some of the main limitations of incremental sheet forming.
Incremental sheet forming (ISF), particularly single-point incremental forming (SPIF), is known for its flexibility in producing prototypes, personalised products, and small batches without the need for expensive tooling. However, these processes are often limited by the uneven wall thickness of the product, accuracy, and the difficulty of processing thicker or difficult-to-form materials. To overcome these challenges, the researchers developed a machine based on a servo-hydraulic press. CNC machines and robotic systems are often used for the SPIF process, but are not suitable for more challenging materials due to their limited stiffness and achievable forces. The hydraulic concept offers greater rigidity and higher forces in the direction perpendicular to the formed sheet metal, which considerably expands the range of materials that can be processed. It is worth mentioning that the machine successfully demonstrated the forming of dual-phase steels – a group of high-strength materials that are of great importance in many industries. The newly developed machine can also perform hybrid two-step forming, in which pre-bulging and SPIF are combined in a single process without the need to unclamp the workpiece. Such a hybrid approach improves the uniformity of the thickness distribution of the final product.
Figure 1: a) Initial clamping of the workpiece, b) clamped workpiece during SPIF process and c) initial position of the ram and the additional assembly mounted on the press table.
The research results show the great potential of the hybrid forming machine presented, the concept of which can also be transferred to larger industrial presses. The concept developed offers an industrially applicable framework for the further development of production, as it combines the flexibility of incremental forming with the achievable forces and rigidity of hydraulic systems. The first author of the article, Tch. Asst. Luka Sevšek, emphasises: “The development of the machine represents a scalable and industrially relevant solution for the future of incremental forming, as it enables the processing of advanced materials and thicker sheets and opens up new possibilities for use in the automotive, aerospace, biomedical and other high-tech industries.”