Although the electric spindle does not seem to be very large, its technical content is not low. Today's EEJA spindle will talk about the cooling technology of the electric spindle.
There are two main internal heat sources in the electric spindle, that is, the heat of the built-in motor and the heat of the spindle bearing. If these two heat sources are not controlled, the thermal deformation caused by them will seriously reduce the machining accuracy of the machine tool and the service life of the bearing, thus shortening the service life of the electric spindle. Because the electric spindle adopts the built-in spindle structure, the motor located in the spindle unit can not use the fan for heat dissipation, resulting in poor natural heat dissipation conditions. In the process of motor energy conversion, the internal power loss will lead to the motor heating. Some researches show that 1 / 3 of the motor heating is generated by the motor rotor, and the rest 2 / 3 of the heat is generated by the motor stator. Therefore, the way to solve the motor heating problem is to use the circulating flow of coolant to implement forced cooling, and the external circulation is generally used Water cooling device to cool the motor stator. The heating of the bearing is mainly caused by the friction between the roller and the raceway. At present, the method to reduce the heating of the bearing is to reduce the diameter of the ball properly and to adopt a reasonable lubrication method. Reducing the diameter of the ball can reduce the friction, thus reducing the heat output. Using reducing the diameter of the ball, the oil air lubrication not only has the lubrication effect on the bearing, but also has a certain cooling effect.