For the lubrication technology of motorized spindle, high-speed motorized spindle must adopt a reasonable and controllable bearing lubrication method to control the temperature rise of the bearing, so as to ensure the accuracy and stability of the process system of numerical control machine tools. At present, the lubrication methods of motorized spindle using rolling bearings mainly include grease lubrication, oil mist lubrication and oil-gas lubrication.
Grease lubrication is a common lubrication method in motorized spindles with relatively low rotational speed. Grease lubricated motorized spindle has simple lubrication system, convenient use, no pollution and strong versatility.
Oil mist lubrication has the dual functions of lubrication and cooling. It uses compressed air as power, atomizes oil and mixes it into the air flow through an oil mist sprayer, and then transports it to the position where lubrication is needed. Oil mist lubrication requires simple equipment, convenient maintenance, and relatively low price. It is a commonly used lubrication method for high-speed motorized spindle. However, it has the disadvantages of polluting the environment and high fuel consumption. With the improvement of people's requirements for environmental protection, the oil mist lubrication method will be gradually eliminated.
Oil and gas lubrication technology uses compressed air to continuously and accurately supply a small amount of lubricating oil to each set of main shaft bearings. The small oil droplets roll again and form an elastic dynamic pressure oil film between the outer raceways, while compressed air can take away part of the heat generated by the operation of the bearings.
Practice shows that too much or too little oil supply in re-lubrication is harmful, while the first two lubrication methods cannot accurately control the amount of oil supply, which is not conducive to the improvement of spindle bearing speed and life. However, the newly developed oil-gas lubrication method can accurately control the amount of lubricating oil at each friction point and has extremely high reliability. Practice has proved that oil-gas lubrication is the most ideal lubrication method for high-speed and high-power motorized spindle bearings, but it requires complicated equipment and high cost. Due to the ideal lubricating effect of oil and gas, it has become the most popular in the world.