Rotary swaging

P09 - Control of component properties during rotary swaging

Investigation and measurement methods were developed to understand and modify the formation of residual stresses during rotary swaging. It was found that modifications to the process influence the state and amplitude of the stresses in the forming zone as well as their distribution on the surface and in the depth of the workpieces. The residual stresses on the surface of the workpieces were changed by the swaging tools used. This is related to a change in the material flow, which leads to a certain stress distribution and pressure distribution in the forming zone. The depth profiles of rotary swaging tubes were altered by the use of mandrels in the pressure zone, which is due to an obstructed radial material flow. Multi-stage forming was carried out with several tools as well as combined in one tool. The residual stresses on the surface remained constant. With the reduction to smaller diameters, the residual stress depth profile shifted to the compression area, which can be explained by the increased pressure in the forming zone and the associated greater depth of material flow. Various effects of the process on the residual stress variations were also investigated. One of the main influences was found to be the initial state of the material, which tends to fluctuate more with very soft material. Depending on the incremental process characteristics and the various parameters influencing the final surface distribution, an adjustment must be made. Calibration strokes to homogenize the residual stresses on the surface were therefore found to be a practical way of reducing the fluctuations. Finally, it should be mentioned that for industrial applications, the residual stresses and the resulting mechanical properties of the workpiece as well as the geometry and surface properties of the workpieces must be adapted and taken into account together in the process design. Torsion tests have shown that residual stresses introduced in the rotary swaging process have a positive effect on the fatigue properties of tubes.

Publications

L. Langstädtler, K. Moazzez, D. Charni, C. Schenck, J. Epp, B. Kuhfuss: Residual stresses generation in multi-stage rotary swaging of steel tubes. CIRP Global conference on sustainable manufacturing, 2023 (accepted).

I. Bösing, S. Ortmann-Ishkina, M. Herrmann, C. Schenck, B. Kuhfuß, M. Baune: Control of corrosion features by forming parameters. ESAFORM 2021, 14 - 16 APRIL, 2021, LIEGE.

D. Charni, S. Ishkina, J. Epp, M. Herrmann, C. Schenck, B. Kuhfuss: Complementary methods for assessment of residual stress fields induced by rotary swaging of steel bars. 13th International Conference on the Technology of Plasticity (ICTP 2021), July 25-30, 2021, The Ohio State University, Ohio.

A. Franceschi, J. Stahl, C. Kock, R. Selbmann, S. Ortmann-Ishkina, A. Jobst, M. Merklein, B. Kuhfuss, M. Bergmann, B.-A. Behrens, W. Volk, P. Groche: Strategies for residual stress adjustment in bulk metal forming. Archive of Applied Mechanics, 2021, DOI: 10.1007/s00419-021-01903-7. 4.

Y. Liu, J. Liu, M. Herrmann, C. Schenck, B. Kuhfuss: Material Flow in Infeed Rotary Swaging of Tubes. Materials, 2021, 14 (1) DOI: 10.3390/ma14010058. 6.