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B. Heinzl:
"High-Level Modelling and Simulation of Machine Tools in Energy Optimization of Production Plants";
Poster: ASIM-TCSE Workshop 2012, TU Wien; 2012-02-13 - 2012-02-14; in: "ARGESIM Report", S. Tauböck, F. Breitenecker (ed.); Argesim / Asim, 37 (2012), 3 - 4.

Introduction.
The research project INFO - as one of several current research projects - aims at increasing energy
efficiency in production plants. In this project, this is done by considering various disciplines of energy technology,
production technology and building design in a holistic approach [1]. By creating a comprehensive simulation
model including all micro- and macro-structures, it attempts to make qualified predictions about the effectiveness
of different energy saving approaches and identify potential savings in manufacturing plants [2]. In contrast to
previous (rather static) concepts, this approach allows customized recommendations based on models of the real
facility.
One step of this project includes energy considerations and development of simulation models of the micro-
structures of production plants (individual processes and machines) in order to point out optimization potential
and gain knowledge for merging the individual levels in an ultimately complete simulation. Some of these aspects
are studied in more detail by creating a multi-domain model of a turning lathe as an example of a machine tool.
Modelling Method.
By using a high-level object-oriented component-based modelling method (also called
Physical Modelling), we can combine electrical, mechanical as well as thermal aspects of a machine tool in a
structural manner. The underlying concept of reusing components of modularly structured models also allows
for an easy adaptation of certain parts of the model for other machines later. In order to be able to validate the
developed model against real measurement data, we attempt to create a model of an actual turning lathe, which is
provided by the Institute for Production Engineering and Laser Technology from the Vienna University of Tech-
nology.
Although simulators for object-oriented component-based modelling of physical systems have evolved consider-
ably in the last years, there are still numerical issues when it comes to simulating complex multi-domain systems.
Developing our model in several stages with gradually increasing level of detail lets us identify the numerical
boundaries of the simulation as well as the degree of modelling effort necessary for considering certain reasonable
scenarios, therefore combining the bottom-up modelling approach of the component-based concept with top-down
modelling.
Modelling Stages.
The development of the simulation model is done in three stages. The first stage contains the
main mechanical and electrical components like electric drives, power supply, gear belt drive, leadscrew, slides
for automatic feed and mechanical loads. It also includes a simple calculation model of the cutting forces using
common formulas and parameters [3]. In the second step, the model is extended by the motor control for all drive
motors and thermal components, which take the generated waste heat into account. However, since the second
stage leads us to some numerical boundaries, some adjustments have to be included in the model in order to enable
appropriate simulation performance. The simulation model in the last stage will furthermore include remaining
electrical loads and additional details like elasticity of mechanical parts or heating of the workpiece.
Conclusion.
The object-oriented Physical Modelling approach seems to be a suitable tool for multi-domain mod-
elling of machine tools. The big advantage of creating modular, easily refinable and modifiable models has been
proven. However, appropriate parameterization of our simulation model turns out to have been underestimated,
since many of the needed parameters are not shown in data sheets and their identification would require extensive
measurements on the machine tool.
Future work will focus on refinement of the models as part of the next stages in the top-down modelling process as well as the parameterization of the remaining components. For model validation it is planned to compare the
simulation results of various scenarios against measurement data obtained from the turning lathe.