Project area C

C02: Modeling and design of systems for active controlling of temperature distribution in machine frames

Building upon the basic mechanisms evaluated in phase one the work is going to be transferred towards real machine components. A component combining heat storage and active interface will be integrated in an existing machine structure. This will be accomplished by designing a compensation-structure and implementing it as an interface between heat source and machine structure in order to reduce the influence of non-steady heat input on the thermal behavior. The component will be verified in a monocausal experimental setup emulating a feed drive and afterwards transferred into a real machine structure. The results from this monocausal case will also be used to investigate the interactions in a more complex structure with multiple heat sources and active components.

C03: Concept to determine thermo-elastic deformations by directly measuring local shifts using structurally integrated sensors

With the first phase the applicability of the concept of structurally integrated sensors in machine tools could be demonstrated. Therefore, the second phase focuses on the validation of the concept under real conditions.
The goal of the second application period is the transfer of the developed sensor system to real machine conditions as well as the development of standardized correction methods via the NC-controller. For this, verified measurement applications are integrated into a conventional machine tool. The appropriate deformation model for the evaluation of the measurement data has been specified as well, so a comprehensive validation can be carried out. Moreover, the measurement system which has been integrated in a machine structure in phase 1 is extended to the axis system in order to incorporate the complete kinematic chain between workpiece and tool. The scientific emphasis lies in the conception, realization and verification of effective correction strategies by means of control engineering. These methods shall be implemented in standard machine controllers.

C04: Modelling and optimisation of power losses in electrical drives and their thermal coupling with machine tools

The second phase of the SFB includes two tasks for the subproject C04. On the one hand, the motor models, deduced in the first phase, have to be prepared for implementation in the machine tools control unit. On the other hand, demands founded on the engine design have to be implemented to the given technical constraints. The losses in the drive system as a main heat source are depending on their load and must therefore be mapped with sufficient accuracy. At the same time it is advantageous, to minimize the overall heat input by the drives and therewith the maximal thermal distortion. In addition to these considerations, the correlations found, have to be verified by means of metrological investigations of demonstrators. Among other things, a motor is designed and constructed which is adapted to a machine tool according to the new findings.

C05: Model based method for the evaluation of the solution variants in design and realisation in particular under thermal-energetic, qualitative and economic aspects

Within SFB/Transregio 96, several approaches for the correction and compensation of thermic induced inaccuracies and defects are evolved. These approaches are characterized by different efforts for both their particular creation and implementation and their impact on accuracy and the achievable outcome. Heretofore, the focus of C05 lied on the development of a conceptual assessment model including a metric for the integration of criteria of several efforts and benefits. During the integration phase, the evolved methods will be applied to the relevant sub-projects in order to analyse the effectiveness, efforts and benefits of correction approaches at first. Thus, the derivation of “suitability profiles” of the acquired solution approaches is possible. The focus of the analysis lies on the exemplarily implementation of single solution approaches in integration objects and demonstration machines. Also, potentials for the reduction of efforts resulting from the development and the start-up procedure can be identified.
C05 provides appropriate procedures and documentation guidelines for particular analysis. That includes the suitable application of the testing work piece, which was initially designed for the verification of the effectiveness in regard to working accuracy. Additional usage strategies will be developed in order to examine possible impacts on productivity, long-term performance of the model’s quality and the appropriateness for different technological applications. In cooperation with sub-project A05, simulation-based assessment methods of the machine behaviour will be developed. Simulations should present the effects of a compensation method to a specific machine.
Generally, the solution approaches can be applied for different use cases with specific boundary conditions and requirements. Hence, the assessment of analysis results for typical use cases will be undertaken with special consideration of the perspectives of both machine manufacturers and machine operators. Therefore, the method will be extended by a multi criterial assessment. Finally, considerations of the combinability of correction and compensation methods are aimed in order to extend the assessment method. The results of the mentioned assessment of an approach for a specific use case will be integrated within a model-based information system that aims to support end-users in terms of the appropriate selection of available approaches.

C06: Measurement of behavior and operating state relevant values along the thermal effect-chain for analysis, evaluation, simulation and correction on the example of a specific test bed machine.

The project C06 deals with the metrological analysis along the thermal effect chain on the example of a specific test bed machine. The methodology developed in the first phase of the CFC 96, consisting of selective thermographic temperature measurement, photogrammetric measurement of deformations and displacements and distributed data logging, will be improved to increase the accuracy, robustness and speed of measurement. The methodology will be implemented in a simplified, portable measurement system to make it applicable for analysis and evaluation in other projects. The correction approaches developed in the projects B05, B06 and B07 and the compensation approaches developed in C02 and C03 will also be implemented in the test bed machine and evaluated by project C05.

T01: Modeling of the thermo-elastic behavior of an external driven spindle

During this project, we envision a technology transfer of insights gained during the first phase of the SFB/TR96 project derived from experimental tests and simulations of bearings and separately driven spindles into industrial application. First, the models are combined and adapted to new products of Chiron-Werke GmbH & Co. KG. In a subsequent step, an existing correction model from B06 can be parameterized in order to examine displacements of the spindle nose. Finally, the spindle is integrated into a complete machine and the models are optimized in order to represent an actual mode of operation. This transfer project is conducted by the WZL of RWTH Aachen and supported by Chiron.

T02: Transfer project: Thermo-energetic intelligent tempering of machine tools’ beds (Machine beds’ tempering)

The aim of the transfer project is a demand-orientated design of the structure and the operation of cooling systems in machine tools based on a machine bed made of high-strength concrete (HPC) with built-in thermo couples and cooling ducts – in particular to improve the energy efficiency. Furthermore, the task is closely linked to the objective of realising a balanced temperature field in the machine bed. Thus, the current deficiencies can be corrected in order to increase the achievable accuracy and productivity.
The complexity of the presented research topic requires detailed system analysis of selected cooling systems and their specific impact on the machines’ behaviour under operating conditions. On this basis, a thermal model of the machine bed is developed considering the knowledge of machine, cooling equipment and electric motor manufacturers. Thus, the impact on the accuracy of the machine and the energy requirements of the components can be analysed in detail. This will provide the basis for the development of strategies and concepts for controlled, demand-orientated coolant flows inside the machine bed.
Criteria for the realisation of the optimal operating point will be defined by taking into account realistic operation conditions such as load regime and ambient temperature, as well as using the data of the built-in temperature sensors. Furthermore, relevant control variables are investigated with respect to their influence on the temperature field. With the aim to provide a demand-orientated temperature control at the optimum operating point, the corresponding consequences for cooling unit sizing, coolant management and system configuration/control can be derived.