Diagnostics of machine tool load-carrying systems weak points with respect to static stiffness criterion

Static and dynamic properties of a machine tool load-carrying system influence significantly its utility features. Accuracy of a machine tool depends clearly on MTLCS stiffness. Deformations of elements and contact joints of MTLCS cause relative displacements of working assemblies of machine tool influencing, in consequence, quality of machined parts. Since modem machine tools should indicate a high accuracy, it is extremely important to diagnose the weak points of construction from the point of view of stiffness during experimental investigations of the prototype. Paper will discuss the method, elaborated at Institute of Manufacturing Engineering of Technical University of Szczecin, of experimental diagnosis of MTLCS weak points with respect to static stiffness. The concept and measurements techniques will be presented. Assumptions, MTLCS experimental model and requirements concerning the experiment aimed at stiffness determination (especially the stiffness of guideway connection) will be described. Experimental stand will be presented in details. Algorithm of experimental results elaboration that enables obtaining a diagnostic information will be discussed. Paper will present results of diagnostic examinations of the milling machine and lathe. These results will be compared with FEM analysis. On the basis of the analysis and results discussion the recommendations for machine tools designers will be formulated.