Electric spindleHow to deal with severe heating during high-speed rotation?

Analysis and processing: The heating and temperature rise issues during the operation of the electric spindle have always been the focus of research. There are two main heat sources inside the electric spindle unit: one is the spindle bearing, and the other is the built-in main motor.

The most prominent issue with the electric spindle unit is the heating of the built-in main motor. Due to the fact that the main motor is located next to the spindle bearing, if the heat dissipation problem of the main motor is not solved properly, it will also affect the reliability of the machine tool operation. The main solution is to adopt a circulating cooling structure, which can be divided into external circulation and internal circulation. The cooling medium can be water or oil, so that the motor and the front and rear bearings can be fully cooled.

The spindle bearing is the core support of the electric spindle and also one of the main heat sources of the electric spindle. Currently, most high-speed electric spindles use angular contact ceramic ball bearings. Because ceramic ball bearings have the following characteristics:
1. Due to the light weight and low centrifugal force of the ball bearings, the dynamic friction torque is small.
2. The thermal expansion caused by temperature rise is small, which stabilizes the preload force of the bearing.
3. Small elastic deformation, high stiffness, and long service life.

Due to the high operating speed of electric spindles, there are strict requirements for the dynamic and thermal performance of spindle bearings. Reasonable pre tightening force and good and sufficient lubrication are necessary conditions to ensure the normal operation of the spindle. Oil mist lubrication is adopted, and the inlet pressure of the atomization generator is 0.25-0.3MPa. 20 # turbine oil is selected, and the oil droplet speed is controlled at 80-100 drops/min. Lubricating oil mist not only fully lubricates the bearings, but also takes away a large amount of heat. The distribution of lubricating oil between the front and rear bearings is a very important issue that must be strictly controlled. The cross-section of the intake port is greater than the sum of the cross-sections of the front and rear fuel injection ports, and the exhaust should be smooth. The injection angle of each fuel injection hole should be at a 15 degree angle to the axis, so that the oil mist can be directly sprayed into the working area of the bearing.