Process combination of lateral extrusion and shear forming with straight tool motion to manufacture crankshaft-like components
Final Report Abstract
Processes of the shear forming technology rarely are used in cold forging as most of the parts feature rotational symmetric geometries. Therefore, this project investigated a novel process combination of lateral extrusion and shifting using numerical modelling and experimental in- vestigations. Compared with the usual process combination of upsetting and shifting, the new process combination enables a superposition of compression stress in the forming zone due to the axial material flow through the die. In the course of tool development and die design, important process parameters were deter- mined using a simplified simulation model. For these investigations, a constant ratio between axial and lateral die movement was used. In addition, the lateral material flow crosswise to the shifting direction was not restricted. With these specifications, influences of die and workpiece geometry on material flow, stress and strain distribution during the process and resulting die loads were investigated using the materials EN AW-6082 and 16MnCrS5. In the following investigations, a load-driven die movement was applied to the simulation model. Furthermore, elastic dies were assigned to the simulation model to investigate the in- fluence of friction on die load and part geometry. With this simulation model, the benefits of a load-driven shifting movement as a function of punch movement was demonstrated regarding the material flow and the geometry in the central region. Furthermore, this simulation was used to design the tool concept. In the following experimental investigations, mainly workpieces made from 16MnCrS5 were used to investigate the functionality of the new tool. In particular, influences of path-driven or load-driven processes and various ratios between die distance and workpiece diameter on part geometry and die load curves were analyzed. In addition, process limits depending on material failure as a result of the stress distribution in the forming area were determined. The hardness distribution in the symmetry plane of the pressed component made from 16MnCrS5 reveals a hardness increase in the forming area of about 70 % compared to the initial hardness. Furthermore, the hardness in the forming area does not depend on the length of the shifting distance. Therefore, the developed process combination is suitable for parts with a large axis offset, for example crankshafts.
Publications
- Design of a tooling concept for combined lateral extrusion and shifting for manufacturing small crankshafts. International Cold Forging Group, ICFG 2017, China (2017)
Liewald, M.; Pasler, L.
- Querfließpressen und Verschieben. Wt Werkstatttechnik online, (2017), S 708 – 713
Pasler, L.; Liewald, M.
(See online at https://doi.org/10.37544/1436-4980-2017-10-30) - Development of a new cold forging process to produce eccentric shafts. ESAFORM, Palermo, Italy (2018)
Pasler, L.; Liewald, M.
(See online at https://doi.org/10.1063/1.5035018)
