Project in the Field of Research
Application of alternative tool materials for fine blanking of high-strength sheet materials (Cemented Carbides)
The fine blanking of high-strength sheet metal grades places high demands on the material properties of the fine blanking die. In addition to the high compressive strength of the tool material certain ductility is required to endure the alternating dynamic loads without premature failure. The classic cold work tool steels and high speed steels are only suitable for high- and highest-strength sheet metal grades in fine blanking applications. Increased wear occurs and thus the tool life can be reduced. Cemented carbides offer the potential to substitute these materials because of its greater compressive strength. During the stripping process of the punch from the punch grid occur in tensile stresses which can lead to failure of cemented carbides. The reason for the tensile stresses is the clamping force of the sheet metal on the punch. According to current state of the art, the clamping force is described with about 10 % of the cutting force, with increasing sheet thickness; the clamping force is steadily increasing. A precise quantification and technical measurement of the clamping force has not yet been carried out and is not investigated.
The aim of the research project is the determination of the process forces during the fine blanking process; in particular the clamping force. One strategy is the development of an in situ measurement of the clamping force and its quantification. A parametric study with different sheet metal thicknesses and grades deliver an analytical model to describe the clamping force. Additionally, a test stand will be developed to determine usable cemented carbides in dependence of its composition. By means of a parametric study different cemented carbide compositions will be stressed with defined clamping forces to simulate the stripping of the punch. The load is carried out up to the failure of the cemented carbide punch. The use of numerical methods by means of finite element method is used to find the correlation between the stress state from the experimental data and the composition of the cemented carbides to derive an explanatory model. The result is the knowledge of the cause-effect relationships between clamping force, tension and the composition of the cemented carbides that enables a knowledge-based selection of appropriate cemented carbides for the fine blanking.
The project partner thank the german research foundation (DFG) for funding the research project Application of alternative tool materials for fine blanking of high-strength sheet materials.
Do you have questions concerning this research project?
Dr.-Ing. Oksana Baer
Cluster Produktionstechnik 3A 332
Tel.: +49 241 80-27428
Fax: +49 241 80-22293