Thermo-Energetic Design of Machine Tools

  Copyright: © Winandy Experimental setup for the attempts for contact for the hydraulic testing machine.

The main goal of the SFB/Transregio-96 joint research project is to develop and implement a global model for the thermo-elastic behavior of machine tools, which is essential for anticipating the machine’s thermal deformation, and therefore reducing cost and improving accuracy. Specifically the prediction of thermal resistances at the interfaces of machine components within contact is of paramount importance. These thermal resistances occur due to geometrical roughness of the surfaces in contact and are quantified by means of contact heat transfer coefficients.

For the accurate prediction of contact heat transfer coefficients, a numerical simulation tool has been developed at the Institute for Heat and Mass Transfer (WSA), which consists of three subsequent steps. Firstly, a surface geometry is modeled, which then undergoes elastic-plastic deformation. Finally, the contact heat transfer coefficient is derived from a numerically calculated three-dimensional stationary temperature field of the modeled specimen.

In addition to the comparative data from the literature, own experimental investigations are carried out for validation. In a hydraulic testing machine at test samples with different initial temperatures are compressed. The temporal change in temperature is recorded with an thermographic infrared camera. The time-resolved temperature data is used to calculate the thermal resistance in the contact plane using algorithms for solving the respective inverse heat conduction problems. The novelty of this method is, that it enables the instantaneous determination of time-varying contact heat transfer coefficients, which usually prevail on the machine tool.