Smart Pressure Film Sensor for Machine Tool Optimization and Characterization of the Dynamic Pressure Field on Machine Surfaces

Abstract

Knowledge of thermal interactions with the environment is essential for improving the performance of machine tools. Therefore, it is necessary to detect and quantify the convective heat flows at machine tool surfaces, that occur in the workspace as a result of cutting fluid use or outside the machine due to active air flow. Thin-film sensors made of shape memory alloys with integrated small temperature sensors are suitable for detecting very fine pressure differences and can be used to estimate convective heat transfer. By measuring the pressure differences, the dynamic pressure field at the surface can be determined. Since the pressure field correlates with the flow field, conclusions can be drawn about the flow velocity. This leads to more profound and extended possibilities to match flow fields from CFD simulations with measured data. At the same time, the surface temperature is also recorded by this sensor. Reference measurements of the temperature in the free flow are used to characterize the heat transfer. By knowing the pressures, temperatures and the correlating flow velocity near the wall, the heat transfer coefficient can be determined. Against this background, this paper demonstrates the behavior of shape memory alloys as fluid pressure sensors and addresses the development of such sensors for machine tools. For this purpose, sensor units are to be developed that can be placed as a sensor network (composite of several sensors on one surface) inside and outside the workspace.