Pose-Dependency of Machine Tool Structures: Appearance, Consequences, and Challenges for Lightweight Large-Scale Machines

Large-scale machine tools for the manufacturing of large work pieces, e.g. blades, casings or gears for wind turbines, feature pose-dependent dynamic behavior. Small structural damping coefficients lead to long decay times for structural vibrations that have negative impacts on the production process. Typically, these vibrations are handled by increasing the stiffness of the structure by adding mass. This is counterproductive to the needs of sustainable manufacturing as it leads to higher resource consumption both in material and in energy. Recent research activities have led to higher resource efficiency by radical mass reduction that is based on controlintegrated active vibration avoidance and damping methods. These control methods depend on information describing the dynamic behavior of the controlled machine tools in order to tune the avoidance or reduction method parameters according to the current state of the machine. This paper presents the appearance, consequences and challenges of the pose-dependent dynamic behavior of lightweight large-scale machine tool structures in production. It starts with the theoretical introduction of the challenges of lightweight machine tool structures resulting from reduced stiffness. The statement of the pose-dependent dynamic behavior is corroborated by the results of the experimental modal analysis of a lightweight test structure. Afterwards, the consequences of the pose-dependent dynamic behavior of lightweight machine tool structures for the use of active control and vibration reduction methods are explained. Based on the state of the art of pose-dependent dynamic machine tool models and the modal investigation of an FE-model of the lightweight test structure, the criteria for a pose-dependent model for use in vibration reduction are derived. The description of the approach for a general posedependent model of the dynamic behavior of large lightweight machine tools that provides the necessary input to the aforementioned vibration avoidance and reduction methods to properly tackle machine vibrations is the outlook of the paper.




References:
[1] A. Karim, A. Verl, and R. Höhne, “Schwingungsanalyse an
Bearbeitungsrobotern. Durchführung einer experimentellen
Modalanalyse an Industrierobotern,” wt Werkstatttechnik online, vol.
104, pp. 49–54, 2014.
[2] H. Vieler, A. Karim, and A. Lecher, “Drive Based Damping for Robots
with Secondary Encoders,” in The International Conference on Flexible
Automation and Intelligent Manufacturing 2015.
[3] J. J. Zulaika, F. J. Campa, and Lopez de Lacalle, L. N., “An integrated
process–machine approach for designing productive and lightweight
milling machines,” International Journal of Machine Tools and
Manufacture, vol. 51, pp. 591–604, 2011.
[4] P. Sekler, A. Dietmair, A. Dadalau, H. Rüdele, J. Zulaika, J. Smolik, et
al., “Energieeffiziente Maschinen durch Massenreduktion. Energiebedarf
von Produktionsmaschinen senken durch Reduktion bewegter Massen
und steuerungstechnische Kompensation der Steifigkeitsverluste,” wt
Werkstatttechnik online, vol. 97, pp. 320–327, 2007.
[5] L. Uriarte, M. Zatarain, D. Axinte, J. Yagüe-Fabra, S. Ihlenfeldt, J.
Eguia, et al., “Machine tools for large parts,” CIRP Annals -
Manufacturing Technology, vol. 62, pp. 731–750, 2013.
[6] H. Dubbel, W. Beitz, K.-H. Küttner, and B. J. Davies, Dubbel.
Handbook of mechanical engineering. London, New York. Springer-
Verlag, 1994.
[7] A. Dietmair, P. Sekler, J. Larranaga, J. Sveda, M. Sultika, and A.
Bustillo, “Schwingungsreduktion bei Produktionsmaschinen. Ein
Überblick über Methoden zur Schwingungsunterdrückung und
Anregungsvermeidung,” wt Werkstatttechnik online, vol. 97, pp. 307–
313, 2007.
[8] Y. Altintas, Manufacturing automation. Metal cutting mechanics,
machine tool vibrations, and CNC design. Cambridge, New York.
Cambridge University Press, 2012.
[9] C. Dripke, F. Groh, M. Keinert, and A. Verl, “A New Approach to
Interpolation of Tool Path Trajectories with Piecewise Defined
Clothoids”, pp. 249–254.
[10] A. Dietmair and A. Verl, “Drive Based Vibration Reduction for
Production Machines,” in International Congress MATAR 2008, Prag,
September 16-17.
[11] W. Singhose, “Command shaping for flexible systems: A review of the
first 50 years,” Int. J. Precis. Eng. Manuf., vol. 10, pp. 153–168, 2009.
[12] N. Loix and J. P. Verschueren, “Stand Alone Active Damping Device,”
in 9th International Conference on New Actuators (ACTUATOR 2004),
Bremen, June 14-16).
[13] E. Abele, M. Roth, C. Ehmann, and M. Haydn, “Aktiver
Strukturdämpfer. Dimensionierung, Konstruktion und Verifikation an
einem Bearbeitungszentrum,” wt Werkstatttechnik online, vol. 100, pp.
105–111, 2010.
[14] A. Ast, S. Braun, P. Eberhard, and U. Heisel, “An adaptronic approach
to active vibration control of machine tools with parallel kinematics,”
Prod. Eng. Res. Devel., vol. 3, pp. 207–215, 2009.
[15] B. Li, H. Cai, X. Mao, J. Huang, and B. Luo, “Estimation of CNC
machine–tool dynamic parameters based on random cutting excitation
through operational modal analysis,” International Journal of Machine
Tools and Manufacture, vol. 71, pp. 26–40, 2013.
[16] I. Zaghbani and V. Songmene, “Estimation of machine-tool dynamic
parameters during machining operation through operational modal
analysis,” International Journal of Machine Tools and Manufacture, vol.
49, pp. 947–957, 2009.
[17] M. Reuss, A. Dadalau, and A. Verl, “Friction Variances of Linear
Machine Tool Axes,” Procedia CIRP, vol. 4, pp. 115–119, 2012.
[18] A. Jönsson, J. Wall, and G. Broman, “A virtual machine concept for
real-time simulation of machine tool dynamics,” International Journal of
Machine Tools and Manufacture, vol. 45, pp. 795–801, 2005.
[19] M. Law, Y. Altintas, and A. Srikantha Phani, “Rapid evaluation and
optimization of machine tools with position-dependent stability,”
International Journal of Machine Tools and Manufacture, vol. 68, pp.
81–90, 2013.
[20] P. Sekler and A. Verl, Real-Time Computation of the System Behaviour
of Lightweight Machines. A Possible way for Vibration Reduction for
Production Machines. Porto, 20-25 September.