In high-speed machining, the thermal characteristics of the electric spindle is a main factor that affects the machining accuracy, and directly affects the increase in the speed of the electric spindle. In the temperature rise of the electric spindle unit, the bearing temperature rise is an extremely important component. The temperature rise and temperature distribution of the bearing have a great influence on the performance of the bearing. It will affect the assembly of the bearing, the working clearance of the bearing, and the performance of the lubricant. An increase in temperature will worsen the lubrication state of the bearing, leading to premature bearing failure. Therefore, the thermal analysis of the bearing system can help us choose and use the bearing reasonably, and can provide a basis for the failure and failure analysis of the bearing system.
At present, the electric shaft usually adopts precision angular contact bearings that are suitable for high speed and can bear radial and axial loads at the same time. The test shows that the three main parameters of the oil-air lubrication system (kinematic viscosity of lubricating oil, compressed air pressure, compressed air flow) affect the temperature rise of precision angular contact bearings, and the following conclusions are drawn:
The viscosity of lubricating oil affects the temperature rise of the bearing through the internal friction and heating of the bearing. With the increase of the viscosity, the temperature rise of the bearing will increase, and this trend is more obvious in the high-speed section, but as the viscosity further increases, the bearing temperature rises. The ascending gradient shows a decreasing trend. The flow and pressure of the compressed air affect the temperature rise of the bearing through the convection heat of the compressed air and the bearing. Within the compressed air pressure range, the temperature rise of the bearing decreases with the increase of the pressure, but this trend is not very obvious. Increasing the compressed air flow can reduce the temperature rise of the bearing, and as the speed increases, the cooling effect will become more and more obvious.
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