Development of an oil-air lubrication system with a piezoelectric nozzle for machine tool spindles.

Oil air lubrication is an effective lubrication method for the high speed spindle of machine tools. However, the rate of oil supply to the bearing fluctuates markedly due to intermittent oil supply from the oil air mixing valves. In this study an oil air mixing apparatus is developed by applying a piezoelectric nozzle which has been used to the printing head of ink jet printers. By using the piezoelectric nozzle instead of the conventional mixing valve, fluctuation of the oil supply is successfully controlled. Further, it becomes possible to attach the oil air mixing equipment in the vicinity of the bearings. The oil supply rate can be, therefore, quickly changed in response to changes in the running condition of the bearing.