Efficient parameterization of structural dynamic main spindle models

• Applicant: Professor Dr.-Ing. Christian Brecher
• Subject Area: Production Automation and Assembly Technology ; Engineering Design, Machine Elements, Product Development
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 512773132

Information about the properties of the components of a machine tool during operation becomes increasingly important in the context of the topics Industry 4.0 and Digital Twin. The main spindle and its properties are very important in machining. In the context of machining-quality-sensitive applications, such as condition monitoring or process force measurement, knowledge of the current physical properties of the main spindle, as an important component of a machine tool, is of great importance. The structural dynamic properties of the main spindle are influenced by different mechanical and thermo-elastic effects during operation, whose monitoring as well as model-based mapping represent a demanding task. To enable the identification of the static and dynamic properties of the main spindle, sensors are integrated into the spindle in order to measure the relative displacement between the spindle shaft and the spindle housing.This research project aims to develop and investigate a method for the efficient process-parallel parameterization of a model, which simulates the elastic properties of the main spindle. The initial parameterization of the model is based on a simulation and experiments with additional measurement setups. The process-related changes in the structural dynamic properties are taken into account in the adaptive model based on the information from the spindle-integrated sensors and the machine-internal data. Two approaches are defined in this research project for the identification of the structural dynamic properties during operation. The first approach focuses on the identification of the structural dynamic properties based on the simultaneous acquisition of the displacement of the spindle shaft and the process forces identified with machine-internal data. This approach allows the calculation of the static stiffnesses of the main spindle system as well as the indirect determination of its dynamic properties. The second approach is based on the identification of the structural dynamic spindle properties during the execution of standard machine-internal functions, such as tool change, rapid traverse, etc. During the execution of such standard functions, mechanical loads affect the main spindle. The analysis of these loads identifies the actual structural dynamic properties of the main spindle. The validation of the methods is carried out with the aid of process forces measured by means of a force measuring platform and determined on the basis of the parameterized model. With this procedure, the method can be validated in a wide loads spectrum in process-relevant frequency ranges.

• DFG Programme: Research Grants