Negative Poisson’s Ratio-Spacer Design and Its Thermo-Mechanical Coupling Analysis Considering Specific Force Output

Aiming at the problems of a complex structure or poor controllability of the existing bearing preload control devices, a method of self-regulation via a negative Poisson’s ratio (NPR) spacer is proposed. Firstly, the principle of preload automatic adjustment at the bearing operation was introduced and the NPRs with three types of cell structures were analyzed. Furthermore, a thermo-mechanical coupling analysis model of the NPR spacer was established and the deformation and force output characteristics of the NPR spacer were studied and experimentally verified. It is found that the concave hexagonal cell structure has the optimal deformation characteristics for bearing preload adjustment. When the temperature is considered, the absolute value of Poisson’s ratio of the NPR spacer decreases as the speed increases and the elongation of the NPR spacer and the output forces are much larger than those without temperature consideration. With the increase in temperature or rotating speed, the axial elongation and output forces of the NPR spacer increases while the effect of temperature is relatively larger.

Research on optimization of spindle bearing preload based on the efficiency coefficient method

Purpose The purpose of this paper is to research on optimization of spindle bearing preload based on efficiency coefficient method and provide theoretical guidance for variable preload of intelligent spindle. Design/methodology/approach Based on an established thermo-mechanical coupling model of angular contact ball bearing with fix-position preload, temperature rise and axial stiffness of the bearing at different speeds and preload are analyzed, and life of the bearing is estimated by the improved L-P theory. The bearing temperature rise, axial stiffness and life data are standardized, and the preload is optimized by the efficiency coefficient method according to the requirements of operating conditions. Findings The optimized preload meets comprehensive requirements of the bearing temperature rise, axial stiffness and life under different operating conditions. Originality/value In the past studies, it is rarely reported that temperature rise, stiffness and life of the bearing under thermo-mechanical coupling effect are used as objective functions to optimize preload at different speeds. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-06-2020-0205/