Specific principles of work area stiffness measurement applied to a modern three-axis milling machine

Abstract

The paper discusses continuous measurement of the machine working space stiffness. In comparison with the conventional stiffness measurement, this is a specific measurement because the influence of the load velocity on the static output characteristic is also shown. This effect is undesirable in terms of detecting the real stiffness of the machine, but at the same time, it is also a diagnostic indicator as it is—as of now—an unexplored parameter of static stiffness. For example, if the load speed is exceeded by deformation of 5 μm s−1, the stiffness of the machine increases considerably. The stiffness changes from 43 to 84 N μm−1, i.e., it approximately grows to double. In order to eliminate the misrepresentation of the course of stiffness, the load speed was reduced and special evaluation software was applied. The measurement methodology is highly effective in terms of measurement time, and it is suitable for the development of a portable facility measuring machine stiffness.