Highly Sensitive Measuring System for Rail Width and Point-Related Hydrodynamic Pressure in Linear Sliding Guideways of Machine Tools

Due to their high damping and the associated low dynamic excitation of the machine tool, hydrodynamic guideways are necessary for precision machines such as grinding machines. This article summarizes the development of the measuring system that was integrated into the guiding rail of a linear hydrodynamic bearing and presents the experimental evaluation. The measuring system is aimed at providing a better understanding of the actual transient hydrodynamic pressure and lubrication condition during the reversing sliding motion in the liquid friction range. The system was checked for its frequency response to ensure that the expected pressure rise during the stroke motion can be measured both in relation to the rail width and to the point. The evaluation is based on Reynolds’ analytical hydrodynamic theory, as numerical calculation approaches themselves are also subject to considerable uncertainties, particularly with regard to the actual geometry of the lubrication gap. The novelty of the results lies in the possibility of analyzing the instationary behavior of a reversing linear bearing of a carriage in machine tools at very low pressures as a quasi-2D and 3D pressure curve. Finally, the new possibilities are demonstrated by analyzing the behavior of a carriage with concave sliding surfaces.