Session 1: Holistic modelling strategies

Efficient modelling and computation of structure-variable thermal behaviour of machine tools
S. Schroeder (a), A. Galant (a), B. Kauschinger (a), M. Beitelschmidt (b)
(a)    Institute of Machine Tools and Control Engineering, TU Dresden
(b)    Institut of Solid Mechanics, TU Dresden

Thermal models are used to improve the thermal behaviour of machine tools. They are used for evaluation of design alternatives and for controller based correction. Therefore lumped parameter network models and finite element models with reduced model order are utilized. For both of these model variants methods for efficient modeling and computation are presented. Based on this, a new concept is presented that combines the two model variants appropriate for the given problem. This combination allows a continuous model development alongside the machine design process.

Parameter identification software for various thermal model types
B. Hensel (a), S. Schroeder (b), K. Kabitzsch (a)
(a)    Institute of Applied Computer Science, TU Dresden
(b)    Institute of Machine Tools and Control Engineering, TU Dresden

For modeling the thermal behaviour of machine tools, a wide range of model types is used, reaching from finite element models over thermal network models to simple transfer functions. All model types have in common that the parameters of each model have to be optimized to fit to the real, modeled machine as closely as possible, i.e. the parameters have to be identified using real measurements. In this paper, a new software solution is presented which allows parameter identification in a unified way. Additionally, a comparison of the accuracy reached by different thermal models for the same modeled machine component is given.

Minimising thermal error issues on turning centre
M. Mareš, O. Horejš, J. Hornych
Research Center of Manufacturing Technology RCMT, Czech Technical University in Prague

Advanced compensation models of machine tool thermal errors were successfully applied on various kinds of milling machines and implemented directly into their control systems as described in the author’s previous works. This paper is focused on applicability of the modelling approach to a completely different machine tool type from an operation principle and mechanical structure point of view: turning centre. The working space is smaller than in milling machine cases and mutual separation of participating heat sinks and sources on resultant thermal error is a real issue. Therefore, different potential inputs into several model structures is discussed in more details.

The methods for controlled thermal deformations in machine tools
A. P. Kuznetsov (a), H.-J. Koriath (b), A. O. Dorozhko (a,b)
(a)    Moscow State University of Technology „STANKIN“
(b)    Fraunhofer Institute for Machine Tools and Forming Technology IWU, Dresden

Existing control methods for the thermal stability of machine tools are based on two fundamentally different principles: – changes in the position of objects of the impact; – change of the thermal state of the objects of the impact. It is substantiated and experimentally shown that the thermal spindle displacement for any machine design solution occur no more than three types of laws out of sixteen possible types of laws. A new concept and algorithm of an sensorless thermal controller for the spindle axis displacement is proposed.

Efficient FE-modelling of the thermo-elastic behaviour of a machine tool slide in lightweight design comprising plugged aluminium plates braced with tie-rods
C. Peukert (a), J. Müller (a), M. Merx (a), A. Galant (a), A. Fickert (a),
B. Zhou (a), S. Städtler (a), S. Ihlenfeldt (a), M. Beitelschmidt (b)
(a)    Institute of Machine Tools and Control Engineering, TU Dresden
(b)    Institut of Solid Mechanics, TU Dresden

In order to represent the thermo-elastic behaviour of a machine structure with braced aluminium plates, the contact characteristics between the plates have to be taken into account. For the purpuse of an efficient analysis, the elastic and thermal partial model are tailored to the different requirements of these physical domains. The difficult identification of the system’s stiffness matrix is carried out indirectly by means of comparison with an experimental modal analysis. Findings from simulations and measurements are compared to validate the thermal and elastic model. A combined thermo-elastic simulation is carried out by mapping the temperature field obtained from the coarse thermal model to the mechanical model.