工作機械主軸用転がり軸受の予圧調整技術

抄録

Spindles used in machine tools, especially machining centers, must operate at high speeds with high stiffness and low temperature rise in order to achieve improvements in productivity and accuracy of the machine. Usually, preloaded angular contact ball bearings are used to satisfy the requirements of low temperature rise and high stiffness. However, there are opposing effects that can result from preloading. Increasing the preload on the bearings to obtain high stiffness causes high temperature rise, which is not suitable for high-speed operations. On the other hand, high preload is necessary to ensure high stiffness when heavy cutting load, low speed conditions are required. This paper introduces the effects of preload control technology by fixed position on temperature rise and stiffness. High-speed operating tests and cutting tests using spindles equipped with preload control units were conducted. The results confirmed that lower preload reduces bearing temperature rise and higher preload improves the cutting surface roughness. Considering these characteristics, an optimum preload control program is proposed to satisfy both low temperature rise and high stiffness.