RADIAL STIFFNESS ANISOTROPY OF BODY BORING FOR LATHE SPINDLE BEARINGS

In the paper there are considered problems connected with the radial stiffness anisotropy of body borings for lathe spindle bearings. Factors having an influence upon stability of its operation characteristics of a machine-tool during idling are considered. The analysis of force factors having an influence upon bearings of a spindle unit during lathe idling is carried out. The work purpose is to determine a quantitative and qualitative situation in the changes of boring forms for spindle bearings under the impact of loads mentioned. As an object of investigations there is chosen the lathe “Vector” manufactured at the Middle-Volga machine-tool plant. A finite element modeling is carried out for deformation investigations in the body boring of the spindle unit under the impact of forces caused by weight and imbalance of the rotating spindle. There is shown a geometrical model of a spindle carrier body, the peculiarities of a finite element model formation and a procedure for the fulfillment of a numerical experiment are described, and approaches of boundary conditions setting are also considered. As a result of a finite element there are obtained values of finite element unit displacements lying on the surface of the body boring of the spindle carrier under the impact of the mentioned power factors. The results found are presented for illustration in the form of solid and flat graphical dependences. The analysis of numerical experiment results has confirmed the presence of the stiffness anisotropy in spindle unit bearings. The phenomenon of stiffness anisotropy in bearings was already under consideration in investigations carried out earlier. But the results of the numerical experiments carried out by us have shown that along with other factors the imbalance forces together with design peculiarities of body parts have an influence upon the constancy of elastic characteristics of bearings. The matter obtained can be used during development of measures for design changes in a spindle unit body with the purpose of stiffness anisotropy decrease in the borings for bearing.