The lower the viscosity of the lubricating oil, the worse the bearing capacity of the oil film, the oil i is easy to break, and the metal materials inside the rolling bearing will come into direct contact with each other, resulting in increased friction and increased wear. Burns and fractures.
However, if the viscosity of the lubricating oil is too high, the frictional resistance will increase, the heat generated by stirring the lubricant will increase, and the energy consumption of the system will increase. On the other hand, for rolling bearings operating under special conditions such as high speed, high load, and high temperature, there may be special requirements for rust prevention, oxidation resistance, wear resistance, and improving the absorption capacity of lubricating oil. Therefore, the choice of lubricating oil is mainly the determination of the viscosity grade of the lubricating oil and the type of additives used or the selection of different lubricants with certain additives. The general principles for selecting a lubricant are as follows.
1.Working temperature. Working temperature affects the viscosity change and lubrication effect of lubricating oil. Therefore, when the operating temperature is low, a lubricant with a low viscosity should be used; when the operating temperature is high, a lubricant with a high viscosity or an appropriate additive should be used. Depending on the ambient temperature, the viscosity of the selected lubricant should also change. For example, when lubricating the same bearing in winter, a lower viscosity lubricant should be used than in the south or summer. When the operating temperature changes frequently, a lubricant with excellent viscosity-temperature characteristics should also be selected, that is, the viscosity of the used lubricant does not change much with the operating temperature to ensure that the oil film thickness is stable within a certain range.
2. The higher the speed of movement, the lower the viscosity of the lubricant should be used to avoid the increase in resistance to movement and excessive heat. Conversely, at low speeds, a lubricant with a higher viscosity should be used to improve the carrying capacity.
3. The nature of movement Impact, vibration, frequent load changes, variable speed, starting, stopping, frequent reversing, and reciprocating or intermittent motion are not conducive to the formation of oil film, so the lubricant with a higher viscosity should be selected. Sometimes it is better to use grease or even solid lubricants to ensure reliable lubrication.
4. Working load. The larger the load the rolling bearing bears, the higher the viscosity of the lubricating oil should be selected, and it should have better oiliness and extreme pressure to prevent the lubricating oil from extruding from the friction pair or direct contact between metals .
5. Structural characteristics. The smaller the radial clearance of the rolling bearing, the higher the processing accuracy of the friction surface, and the lower the viscosity of the lubricant.
6. Environmental conditions. When the bearings are operated under humid, corrosive gas, low temperature, dust, and strong radiation conditions, the lubricant is easily polluted and deteriorated. At this time, water resistance, wear resistance, corrosion resistance, cold resistance, and radiation resistance should be selected. Strong lubricant. In places where running water splashes, emulsion sprays, humid air or dust debris are serious, it is generally not appropriate to choose lubricating oil, but to use grease.
7. Bearing accuracy. When the friction surface of the bearing is rough, it is generally suitable for oils with high viscosity in order to withstand the local large pressure due to poor contact. When the accuracy of the friction surface is high, p selects a low-viscosity lubricant to reduce Little unnecessary energy loss and temperature rise.
8. Bearing hardness. When the hardness of the bearing friction surface is low, a lubricant with a high viscosity should be used, and the amount of oil should be sufficient; otherwise, the viscosity of the lubricant can be reduced. In order to give full play to the role of lubricants, it is important to choose a lubrication method and high-quality lubricant suitable for the conditions of use. When the motor is assembled, the grease injected into the bearing chamber must be cleaned. The grease is not clean, mixed with impurities, especially hard impurities, which may cause abnormal wear of the bearing. The amount of dilute grease should be properly filled. If the amount is too small, the bearing may be caused by intermittent oil shortage and dry grinding. Bearing failure caused by heating; if too much is added, the grease will heat up and cause bearing failure, and it will thin out and pollute the inside of the motor.
The filling of the motor grease must be injected according to the design amount, and it must be in the room; the bearing room space is reasonably allocated. The space of the bearing chamber is composed of three parts, the bearing cavity, and the inner and outer bearing cover. The grease should be distributed as far as possible on the bearing cavity and the surface that can envelope the bearing. The space filled up is determined according to the speed. During the operation of the motor, it is necessary to prevent the deterioration and loss of grease, which will cause bearing failure, and it shall be regularly replenished with special grease for bearings, designed to use an oil return pan. It is strictly forbidden to lubricate with different brands; mixed use can prevent grease from deterioration, loss of lubricating performance and causing bearing failure.