Thermal Error Minimization of a Turning-Milling Center with Respect to its Multi-Functionality
Martin Mareš, Otakar Horejš, and Jan Hornych
Research Center of Manufacturing Technology (RCMT), Department of Production Machines and Equipment,
Faculty of Mechanical Engineering, Czech Technical University in Prague (CTU)
Horská 3, 128 00 Prague 2, Czech Republic
Achieving high workpiece accuracy is a long-term goal of machine tool designers. Many causes can explain workpiece inaccuracy, with thermal errors being the most dominant. Indirect compensation (using predictive models) is a promising thermal error reduction strategy that does not increase machine tool costs. A modeling approach using transfer functions (i.e., a dynamic method with a physical basis) has the potential to deal with this issue. The method does not require any intervention into the machine tool structure, uses a minimum of additional gauges, and its modeling and calculation speed are suitable for real-time applications that result in as much as 80% thermal error reduction. Compensation models for machine tool thermal errors using transfer functions have been successfully applied to various kinds of single-purpose machines (milling, turning, floor-type, etc.) and have been implemented directly into their control systems. The aim of this research is to describe modern trends in machine tool usage and focuses on the applicability of the modeling approach to describe the multi-functionality of a turning-milling center. A turning-milling center is capable of adequately handling turning, milling, and boring operations. Calibrating a reliable compensation model is a real challenge. Options for reducing modeling and calibration time, an approach to include machine tool multi-functionality in the model structure, model transferability between different machines of the same type, and model verification out of the calibration range are discussed in greater detail.
-  J. E. Franke, T. Maier, F. Schäfer, and M. F. Zaeh, “Experimental Evaluation of the Thermal Machine Tool Behavior for Model Updating,” Int. J. Automation Technol., Vol.6, No.2, pp. 125-136, 2012.
-  T. Nozaki and J. Otsuka, “Reduction of Thermal Deformation in a Motor Precision Positioning Device Cooled by Peltier Elements,” Int. J. Automation Technol., Vol.7, No.5, pp. 544-549, 2013.
-  C. Hong and S. Ibaraki, “Observation of Thermal Influence on Error Motions of Rotary Axes on a Five-Axis Machine Tool by Static R-Test,” Int. J. Automation Technol., Vol.6, No.2, pp. 196-204, 2012.
-  C. Brecher and P. Hirsch, “Compensation of thermo-elastic machine tool deformation based on control internal data,” CIRP Annals – Man. Tech., Vol.53, No.1, pp. 299-304, 2004.
-  J. Mayr, J. Jedrzejewski, E. Uhlmann, M. A. Donmez, W. Knapp, F. Härtig, K. Wendt, T. Moriwaki, P. Shore, R. Schmitt, C. Brecher, T. Würz, and K. Wegener, “Thermal issues in machine tools,” CIRP Annals – Man. Tech., Vol.61, No.2, pp. 771-791, 2012.
-  S. R. Postlethwaite, J. P. Allen, and D. G. Ford, “The use of thermal imaging, temperature and distortion models for machine tool thermal error reduction,” Proc. Inst. Mech. Eng., Vol.212, No.8, pp. 671-679, 1998.
-  C. D. Mize and J. C. Ziegert, “Neural network thermal error compensation of a machining center,” Prec. Eng., Vol.24, No.4, pp. 338-346, 2000.
-  M. Gebhardt, A. Schneeberger, S. Weikert, W. Knapp, and K. Wegener, “Thermally Caused Location Errors of Rotary Axes of 5-Axis Machine Tools,” Int. J. Automation Technol., Vol.8, No.4, pp. 511-522, 2014.
-  M. Mareš and O. Horejš, “Modelling of cutting process impact on machine tool thermal behaviour based on experimental data,” Procedia CIRP, Vol.58, pp. 152-157, 2017.
-  C. Brecher and A. Wissmann, “Compensation of Thermo-Dependent Machine Tool Deformations Due to Spindle Load Based on Reduced Modeling Effort,” Int. J. Automation Technol., Vol.5, No.5, pp. 679-687, 2011.
-  S. Xiang, X. Yao, Z. Du, and J. Yang, “Dynamic linearization modeling approach for spindle thermal errors of machine tools,” Mechatronics, Vol.53, pp. 215-228, 2018.
-  S. B. Achour, A. Checchi, G. Bissacco, and L. De Chiffre, “Thermal characterization of a micro polishing machine and effect on path strategy compensation,” Proc. of the 19th Int. Conf. and Exhibition (EUSPEN 2019), pp. 446-447, 2019.
-  T. Moriwaki, “Multi-functional machine tool,” CIRP Annals – Man. Tech., Vol.57, No.2, pp. 736-749, 2008.
-  H. Tachiya, H. Hirata, T. Ueno, Y. Kaneko, K. Nakagaki, and Y. Ishino, “Evaluation of and Compensation for Thermal Deformation in a Compact CNC Lathe,” Int. J. Automation Technol., Vol.6, No.2, pp. 137-146, 2012.
-  L. Ljung, “System Identification Toolbox 7 User’s Guide,” 2009.
-  D. Berger, D. Brabandt, and G. Lanza, “Conception of a mobile climate simulation chamber for the investigation of the influences of harsh shop floor conditions on in-process measurement systems in machine tools,” Measurement, Vol.74, pp. 233-237, 2015.
-  Int. Organization for Standardization, ISO 230-3, “Test Code for Machine Tools – Part 3: Determination of Thermal Effects,” 2007.