Abstract
This paper presents an innovative system determining machine tool quasi-static stiffness in machining space, so-called Stiffness Workspace System (SWS). The system allows for the assessment of the accuracy of a machine which has become a vital aspect over past years for machine tool manufacturers and users. Since machine tools static stiffness is one of the main criteria using to evaluate the machines' quality, it is crucial to highlight the relevance of experimental and analytical stiffness determination methods. Therefore, the proposed method is applied to estimate the spatial variation of static stiffness in the machine tool workspace. This paper describes the SWS system—its design, working principle, mounting conditions and signal processing. The major advantage of the system is the capability to apply forces of controlled magnitude and orientation as well as simultaneously measure the resulting displacements. The obtained results give possibility to estimate and evaluate static stiffness coefficients depending on the position and direction under loaded conditions. The results confirm the validity of the analyses of spatial stiffness distribution in the machine workspace.
Highlights
Accuracy of machining process is significantly influenced by the actual state of the machine tool components and their cooperation
Methods and guidelines for tests for machining centres under finishing conditions are specified in the ISO 230 [2] series, as well as in ISO 10791-7 [3] which deals with the verification of kinematic accuracy of the machine
As machine tool stiffness depends on various effects, e.g., the deflections of machine tool components and properties of connections between them, it is
Summary
Accuracy of machining process is significantly influenced by the actual state of the machine tool components and their cooperation. For the purpose of this paper, the system of machine tool elements is called MTHW system (machine tool—tool—holder—workpiece) Important roles in this system play: characteristics of individual system components, an assembling technology of the machine, physical phenomena taking place during machining process, changeable machining conditions or control systems [1]. Methods and guidelines for tests for machining centres under finishing conditions are specified in the ISO 230 [2] series, as well as in ISO 10791-7 [3] which deals with the verification of kinematic accuracy of the machine These standards concern testing conditions accounting only for geometric errors and deviations resulted from quasi-static load. As machine tool stiffness depends on various effects, e.g., the deflections of machine tool components and properties of connections between them, it is
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