2002 年 68 巻 7 号 p. 938-942
In the oil-air lubrication applied to the high-speed spindle supported with a set of ball bearings, very severe sound noise is emitted so that the high-pressure air supplied through a couple of thin nozzles may collide with balls which are rolling at high speed. In this paper, the sound noise radiated from the spindle unit has been measured, changing the supplied air pressure and the number of nozzles as well as the flange shape of HSK tool holder. A special spindle supported by magnetic bearings is also used for comparison. From those experimental results, it is confirmed that the collision air causes to emit such sound noise.