Extended Conical Tube-Upsetting Test to Investigate the Evolution of Friction Conditions

Abstract:

Friction has a significant influence on almost all metal forming processes. An in situ measurement of the friction stress within the forming process is in general difficult. Therefore, different experimental setups based on the indirect measurement of a friction dependent value are used to determine the friction conditions in laboratory experiments. For example the ring compression test and the conical tube-upsetting test are using the change of the geometrical shape of a specimen to investigate an averaged friction coefficient within the process. The essential advantages of conical tubes are the prevention of sticking friction and a homogeneous displacement and relative velocity along the contact surface depending on the friction conditions and the used cone angle. However, in both methods the development of the friction conditions during the upsetting process and the relative velocity between tool and workpiece are unknown. In this paper an extended setup of the conical tube-upsetting test is presented. The development of the specimen profile is detected by a laser sensor during the process at elevated temperatures. Experiments are conducted for different cone angles and the measured data is compared to FE-simulations. The time-dependent geometric data is used for the calculation of the relative displacement and relative velocity between tool and workpiece at the edge of the contact zone. A comparison with classical nomograms indicates a change of the friction conditions during the upsetting process. Finally, simulations are fitted to the experimental results by using a variable friction coefficient.

• Periodical: Key Engineering Materials (Volume 716)
• Pages: 157-164
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.716.157
• Online since: October 2016
• Authors: Marco Teller*, Alexej Klubakov, Martin Franzke, Johannes Lohmar, Gerhard Hirt
• Keywords: Finite Element Method (FEM), Friction, Friction Parameter Determination, Geometry, Laser

References

[1] R. Kopp, H. Wiegels, Einführung in die Umformtechnik, Verlag Mainz, Aachen, (1999).

[2] A.T. Male, M.G. Cockroft, A Method for the Determination of the Coefficient of Friction of Metals under Conditions of Bulk Plastic Deformation, J. Inst. Met. 93 (1964) 38–46.

[3] M. Burgdorf, Über die Ermittlung des Reibwertes für Verfahren der Massivumformung durch den Ringstauchversuch: Werkzeugmaschinen und Fertigungstechnik. Teil II: Umformtechnik, Industrie-Anzeiger 89 (1967) 15–20.

[4] R. Kopp, F. -D. Philipp, Physical Parameters and Boundary Conditions for the Numerical Simulation of hot Forming Processes, Steel Res. Int. 63 (1992) 392–398.

DOI: 10.1002/srin.199201729

[5] R. Volles, M. Wolske, R. Kopp, Determination of friction coefficient by use of conical tube upsetting test, in: L. Schaeffer (Ed. ), XXI SENAFOR e a IV Conferência Nacional de Conformação de Chapas, 2001, p.24–26.

[6] M.S.H. Al Baouni, Untersuchung des Einflusses unterschiedlicher Prozessbedingungen auf die Reibung bei Umformprozessen. Dissertation, Aachen, (2009).

[7] R. Kopp, M.S.H. Al Baouni, R. Volles, Conical Tube-Upsetting Test-A New Method for Accurate Determination of The Friction Coefficient, in: P.F. Bariani (Ed. ), Proceedings of the 8th International Conference on Technology of Plasticity: Advanced Technology of Plasticity, Ed. Progetto, Padova, 2005, p.645.

[8] M. Plančak, Z. Car, M. Kršulja, D. Vilotić, I. Kačmarčik, D. Movrin, Possibilities to Measure Contact Friction in Bulk Metal Forming, Tehnički vjesnik 19 (2012) 727–734.

[9] A.T. Male, Variations in Friction Coefficients of Metals during Compressive Deformation, J. Inst. Met. 94 (1966) 121–125.

[10] V. Mandic, M. Stefanovic, Friction Studies Utilizing the Ring - Compression Test - Part II, Tribology in Industry 25 (2003) 76–82.

[11] T. Henke, G. Hirt, M. Bambach, Randwertermittlung für die robuste Auslegung von Schmiedeprozessen, Werkstattstechnik online 103 (2013) 783–788.

DOI: 10.37544/1436-4980-2013-10-783