Development of an Oil-Air Lubrication System with Piezoelectric Nozzle for Machine Tool Spindles

Oil-air lubrication is one of the effective lubrication methods for the high-speed spindle of machine tools. However, the oil supply rate to the bearing fluctuates remarkably due to the intermittent oil supply from the oil-air mixing valves. In this study, a new oil-air mixing equipment is developed by applying the piezoelectric nozzle which has been used for the printing head of ink-jet printers. By using the piezoelectric nozzle instead of the conventional mixing valve, the fluctuation of the oil supply is successfully suppressed. And it becomes possible to attach the oil-air mixing equipment close to the bearing. The oil supply rate can be, therefore, quickly changed in response to the change of running condition of the bearing.