Lubrication of rolling bearings

Lubrication is important for rolling bearings. Lubricants in bearings not only reduce frictional resistance. It can also function to dissipate heat, reduce contact stress, absorb vibration, and prevent rust.

    Lubrication methods commonly used in bearings are oil lubrication and grease lubrication. In addition, it is also lubricated with a solid lubricant. Which type of lubrication is used, which is related to the speed of the bearing. Generally, the dn value of the rolling bearing (d is the inner diameter of the rolling bearing, mm; n is the bearing speed; r/min) indicates the speed of the bearing. The dn value limits for grease lubrication and extraction lubrication are listed in the table below as a reference when selecting a lubrication method.
 
     Dn value limit for grease lubrication and oil lubrication (table value × 104) (mm·r/min)

    Grease lubrication

Since the grease is a viscous gel-like material, the lubricating film has high strength, can withstand large loads, is not easy to be lost, is easy to seal, and can be maintained for a long period of time. The grease loading of the wave bearing is generally 1/3~2/3 of the internal space of the bearing. This type of lubrication is ideal for industrial machinery where it is not convenient to add lubricants, or for industrial machinery that does not allow the loss of lubricants. Its disadvantage is that it only works for lower d. value. The main performance indicators of grease will be male and female. If the dn value of the bearing is large and the load is small, the grease with a large penetration degree should be selected; otherwise, the grease with a smaller degree should be selected. In addition, the working temperature of the bearing should be lower than the hot spot of the swelling. For the mineral oil lubrication, it should be 10~20t lower; for synthetic grease. Should be 20 to 30 ° C lower.

    2. Oil lubrication

Under high-speed and high-temperature conditions, oil lubrication can be used when the grease lubrication cannot meet the requirements. The main characteristic of lubricating oil is viscosity. The higher the speed, the lower the viscosity of the lubricating oil. The higher the load, the higher the viscosity of the lubricating oil. According to the working temperature and dn value, the viscosity value of the lubricating oil should be selected, and then the corresponding lubricating oil grade should be selected from the lubricating oil product catalog according to the viscosity.

    When lubricating oil, the common lubrication methods are as follows:

    1) Oil bath lubrication Partially immerse the bearing in the lubricating oil. When the bearing is stationary, the oil level should not be higher than the center of the lowest turret. This method is not suitable for high speed because it causes a large energy loss when the oil is stirred vigorously, causing the oil and the bearing to overheat.

    2) Drip lubrication is suitable for bearing parts that need to supply lubricating oil quantitatively. The amount of oil to be dripped should be properly controlled. Excessive oil quantity will cause the bearing temperature to increase. In order to make the dripping oil smooth, the full loss system with less viscosity is often used. Use oil L-AN15.

    3) Splash lubrication This is a common lubrication method for bearings in general closed gear transmissions. The use of gears to seal the bearings is to prevent dust, water, sour gas and other debris from entering the bearing pads and preventing lubricant loss. And set. Sealing devices can be divided into contact and non-contact types.

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Method for extending the life of a forklift clutch release bearing

Separation bearings of internal combustion forklift clutches work frequently, and the number of damages accounts for a large proportion of forklift failures. If the driver is properly operated and maintained in a timely manner, the bearing can be used for about 3 months, but it must be replaced when it is repaired. If the driver's technical level is low, the forklift that is driven will have the separation bearing damage almost every month. After the damage, other parts will be removed, such as the separation lever and the clutch plate, so that the material cost of equipment maintenance is obviously improved.

    What is the cause of the clutch release bearing being easily damaged? In practice, although the driver is strictly required to dispense oil every time to the separation bearing, this is not only cumbersome, but the bearing is often damaged. According to the analysis, the high temperature of the engine is transmitted to the separation bearing, and the high-speed rotation of the bearing also generates high temperature. Under such conditions, the oil is difficult to remain in the bearing, the bearing operates continuously under high temperature conditions, and the lubrication condition is not good. The cause of frequent damage.

    In response to the above problems, it has also been tried to heat the bearing in the grease to soak the grease into the bearing. After the treatment, the grease can fill the bearing, but the grease is destroyed due to the high temperature treatment. The amplitude is reduced, the effect is not satisfactory with this method, and the service life of the bearing is not extended. We also used a sharp-mouthed grease gun to directly grease the release bearing. Then installed on the car, after observation and inspection, the service life of the bearing is greatly extended. This method of oiling has received satisfactory results, but the operation is more complicated. Then, we explored the case where the engine was not disassembled and the grease was added. The first test was successful on the 475 C engine, and then the 475C and 480 and 492 engines were tested. Both of them received good results. After repeated practice, improvement, and summing up experience, a relatively simple method of oil injection operation was finally formed. The specific process is as follows:

    (l) The engine does not disintegrate the oil filling method. First open the clutch cover to check the wear of the separated bearing. If it is confirmed that the bearing is not damaged or the wear is not exceeded, remove the clutch pedal, adjust the connecting rod pin, and make the separation bearing and its Return the seat to the last position, fill the hole of the bearing housing with a grease gun until the bearing overflows, then turn the bearing slightly, refill the oil, repeat the above work until there is a little butter around the bearing, then Rotate the bearing and observe the amount of oil. If there is resistance to the rotation of the bearing, it is proved that the bearing is filled with butter. Then remove a small amount of butter that has spilled over the separation housing and reassemble the removed pin and clutch cover.

    (2) The oil filling method of engine disintegration exposes the engine to the assembly of the separation bearing and the bearing housing, and uses a grease gun to grease the small oil hole below the inner ring of the separation bearing housing. When the bearing has a butter overflow, the bearing is rotated until the bearing one There are butter spills in the circle.

    After the above two methods are processed, the bearings can be removed without oiling within half a year. After the trial of the oil filling method at Hengshui Railway Station, the mechanical integrity rate was significantly improved and significant economic benefits were achieved. It can save material costs; increase the loading and unloading volume, and increase the loading and unloading capacity by 30t per month. This method has also been promoted at other railway stations and has achieved satisfactory results.

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