“Bearing fatigue is a mechanical phenomenon that occurs when a bearing experiences permanent material damage due to repeated cyclic stresses and strains during operation.”
Fatigue failure of SKF Bearing is a surface form of failure, which is mainly manifested in the initiation, propagation and fracture process of fatigue crack, and the long-term impact of load failure under alternating conditions.Three common maintenance techniques for bearing fatigue failure of SKF rolling mill
Sealed rolling mill bearings are lubricated with specially tested high-quality lithium base grease. This grease can withstand a high temperature of 120 degrees for a short time. If the stable operating temperature reaches 70 degrees or higher, the service life of standard lithium grease will be shortened.
If you want to work at high temperature frequently, you must use special grease, and pay attention to whether you need to use heat-resistant materials as sealing devices. The service temperature of standard contact seal shall not exceed 110 ℃.
The load bearing capacity of the bearing is much smaller than that of the rolling mill bearing with the same volume. Therefore, the radial size of its rolling bearing is large. Therefore, SKF bearings are often used in occasions with large load and occasions requiring small radial size and compact structure (such as internal combustion engine crankshaft bearings).Three common maintenance techniques for bearing fatigue failure of SKF rolling mill
The bearing is particularly sensitive to foreign matters such as metal chips. Once mixed with foreign matters, it will produce intermittent relatively large vibration and noise, which is easy to cause damage. Therefore, the service life of rolling bearings also has a certain limit. In short, the service life of similar bearings is shorter than that of SKF bearings.Three common maintenance techniques for bearing fatigue failure of SKF rolling mill
Three common maintenance techniques for bearing fatigue failure of SKF rolling mill
There are three types of SKF Bearing Maintenance:
Fault maintenance: in case of bearing fault, stop the machine for inspection and maintenance.Three common maintenance techniques for bearing fatigue failure of SKF rolling mill
Regular maintenance: in order to ensure the normal operation of the main engine, set a maintenance cycle for regular maintenance according to the requirements of the main engine and the design theory and use experience of the bearing.
Early warning maintenance: use advanced bearing fault diagnosis technology to monitor the service status of rolling mill bearings in real time, and put forward prediction and maintenance before bearing failure.Three common maintenance techniques for bearing fatigue failure of SKF rolling mill
During the operation of SKF Bearing, there must be sound, temperature and vibration. Therefore, for the maintenance of the running bearing, we can find the abnormal changes of the bearing by listening, touching, observing and using the bearing fault diagnosis instrument, and judge whether the rolling mill bearing is in the normal working state according to the changed state.Three common maintenance techniques for bearing fatigue failure of SKF rolling mill
The clearance of Timken bearing in the United States refers to the movement of the bearing when one side of its inner ring or outer ring is fixed when it is not installed in the shaft or bearing housing, and then the unfixed side moves radially or axially. According to the moving direction, it can be divided into radial clearance and axial clearance.Three common maintenance techniques for bearing fatigue failure of SKF rolling mill
The clearance during operation (called working clearance) has an impact on the rolling fatigue life, temperature rise, noise, vibration and other properties of imported bearings. When measuring the clearance of the bearing, in order to obtain a stable measurement value, the specified measurement load is generally applied to the bearing.
Therefore, the measured value is larger than the real clearance (called theoretical clearance), that is, it increases the elastic deformation caused by the measured load.
However, for the roller bearing of Timken bearing in the United States, the elastic deformation is small and can be ignored. The internal clearance of the bearing before installation is generally expressed by theoretical clearance.Three common maintenance techniques for bearing fatigue failure of SKF rolling mill
The lubrication of bearing is to use oil film to separate the relatively moving rolling surfaces from each other, so as not to fail due to excessive wear caused by rough point contact. If users attach great importance to imported bearing lubrication technology, it can ensure stable performance and rotation accuracy during the given service life.
Rotate the outer ring and carefully wash the junction of cage, rolling body and raceway. Any previously hidden part of oil residue needs to be thoroughly cleaned. Timken bearings should be attached after washing clean, Youlin dry cleaning, clean lined neutral meter support dry, or slowly in the far-infrared drying oven.
Since even dry cleaning, Youlin drying or drying, the whole process should not put the bearing ring to any frame or rolling element. Bearing oil can be removed from the oil sealed package and immersed in acid free 3% kerosene or gasoline before delivery test in practice.Three common maintenance techniques for bearing fatigue failure of SKF rolling mill
Inspection of dripping lubricating oil and immediate delivery of dry or dry bearings shall be required. At this time, there is no oil film to protect the outer surface of the bearing. Three common maintenance techniques for bearing fatigue failure of SKF rolling mill
The inspectors are not allowed to directly contact the skin in the whole process. The operators should wear clean gloves and paint with rust, but they must avoid mixing the antirust agent with the appearance of American Timken bearing, otherwise the deviation of the measurement results will be.Three common maintenance techniques for bearing fatigue failure of SKF rolling mill
It shall be delivered immediately or treated with rusty stock. After the whole inspection process is completed, the imported bearings shall be inspected. Take too long to avoid corrosion. Pay attention to the use of clean and oil-free pure gasoline, which can also cause corrosion.
If the bearing is dry or dry, check the outer surface without bearing oil film protection according to the regulations, drip lubricating oil and deliver it immediately. At this time, the manpower directly contacting the skin is not allowed in the whole inspection process. Three common maintenance techniques for bearing fatigue failure of SKF rolling mill
The operator should wear clean gloves and draw rust by hand, but it must be avoided to mix the hands on the rolling surface of the bearing with rust inhibitor, otherwise it will lead to the deviation of the measurement results.
The inspection of Timken bearings in the United States is completed immediately after delivery or rust counting. During the whole inspection process, try not to last too long to cause corrosion. Pay attention to the use of clean and oil-free pure gasoline, which can also cause corrosion.Three common maintenance techniques for bearing fatigue failure of SKF rolling mill
The lubrication of imported bearings is divided into grease lubrication and oil lubrication. The advantage of grease lubrication is that the lubrication facilities are simple, the grease is not easy to leak, and has the ability to prevent water, air and other impurities from entering the bearing. Three common maintenance techniques for bearing fatigue failure of SKF rolling mill
Therefore, grease lubrication is widely used in general. Lubricate with oil under heavy load, high speed, high temperature and other working conditions.
Lubricating grease is composed of base oil, thickener and filler. The viscosity of base oil plays an important role in the lubricating performance of grease. The composition of thickener has an important impact on the performance of grease, especially temperature characteristics, water resistance and oil precipitation. Filler is mainly used to enhance the anti gasification, anti rust, extreme pressure and other properties of grease.
During bearing installation, mechanical, heating or hydraulic methods can be selected according to its type and size. However, under no circumstances can IKO bearing rings, cages, rolling elements or seals be knocked directly. The force exerted on the linear bearing during installation must not be transmitted from one bearing ring to another through the rolling element, otherwise the raceway may be damaged.
First of all: there are two oil tank equipment, one for use and one for standby. They are switched regularly. The standby oil tank is cleaned, the oil is heated and precipitated, and the oil is purified and separated from water.
A degassing plate in the oil return area shall be set in the oil tank to reduce the impact of refueling; Magnetic grid device – adsorption of iron mechanical impurities in oil return area; Floating oil suction port – oil suction at an appropriate position below the liquid level;
Automatic drainage device or flooding alarm device – discharge the precipitated and separated water in time; Dynamic liquid level control – alarm or interlock for sudden large amount of oil leakage.Three common maintenance techniques for bearing fatigue failure of SKF rolling mill
The filtering accuracy of oil supply is high. Generally, the filtering accuracy is required to reach 10 ~ 20 μ M to ensure the cleanliness of oil products.Three common maintenance techniques for bearing fatigue failure of SKF rolling mill
The oil supply pressure shall be kept constant, and the working pressure control device of the lubrication system shall have high sensitivity and accuracy to avoid working pressure drop due to pressure change, resulting in insufficient oil supply of local lubrication system and wear and sintering of oil film linear bearing.
The volume of the oil tank shall be 35 ~ 40 times of the displacement per minute of the oil pump, and some shall be even larger. Under the condition of high oil level operation, ensure that the oil stays in the oil tank for a long enough time.Three common maintenance techniques for bearing fatigue failure of SKF rolling mill
The pressure tank in the lubrication system must operate normally, control the reasonable oil filling flow value and liquid level in the tank, and play a part in buffering the pressure fluctuation of the system and the supply of emergency oil source.Three common maintenance techniques for bearing fatigue failure of SKF rolling mill
The oil supply temperature shall be controlled between 40 ± 2 ℃ to ensure the viscosity of the oil supply.Three common maintenance techniques for bearing fatigue failure of SKF rolling mill
The filter must exhaust the residual air in the filter cartridge before switching IKO bearings.Three common maintenance techniques for bearing fatigue failure of SKF rolling mill
For IKO bearing rings with clearance fit, it is recommended to apply a thin layer of anti creep corrosion agent on the mating surface to prevent friction corrosion between the mating surfaces.Three common maintenance techniques for bearing fatigue failure of SKF rolling mill
Correct installation is very important for the use of linear bearings. I hope you can use the correct installation method in the future.Three common maintenance techniques for bearing fatigue failure of SKF rolling mill.
Cage noise mainly occurs in ball bearings and tapered roller bearings, When the bearing rotates, it will make a sound due to the vibration of the cage and the impact between the cage and the rolling element.
This sound is periodic. Chatter (various bearings) is a sound with a certain frequency, which is generated by the vibration caused by large waviness on the raceway surface.
Noise caused by improper use: it exists for all kinds of bearings. When the surface of the bearing raceway or rolling element is damaged, dented and rusted, Then there will be periodic noise and vibration Dirt noise will be generated when dust invades the bearing during operation This noise is aperiodic and also accompanied by vibration. Its sound size is not fixed, sometimes not
The effect of bearing vibration on Timken bearing failure is obvious For example: peeling, indentation, corrosion, crack Wear, etc. will be reflected in the bearing vibration detection, so the vibration can be measured by using special bearing vibration measurement devices (frequency analyzer and vibration instrument, etc.) and the specific situation of abnormal vibration can be inferred through the frequency distribution.
The measured values vary according to the service conditions of the bearing or the installation position of the sensor. Therefore, it is necessary to analyze and compare the measured values of each machine in advance and determine the judgment standard
Generally, the temperature of Timken bearing rises slowly with the start of operation and reaches a stable state after 1 to 2 hours The normal temperature of the bearing varies with the heat capacity, heat dissipation, speed and load of the machine If the lubrication and installation are not appropriate, the bearing temperature will rise sharply and abnormal high temperature will appear. In this case, the machine must be shut down and necessary preventive measures must be taken
Although the bearing quality and other aspects are relatively good, the rolling bearing is a precision component, and its use must be carried out carefully accordingly. No matter how high-performance bearings are used, if they are not used properly, the expected high performance will not be obtained. The precautions for the use of bearings are as follows:Three common maintenance techniques for bearing fatigue failure of SKF rolling mill
Keep the bearing and its surroundings clean.
Even small dust that cannot be seen by the eyes will have a bad impact on the bearing. Therefore, keep the surrounding clean so that the dust will not invade the bearing.
Use with care.
Strong impact on Timken bearing during use will produce scars and indentation, which will become the cause of the accident. In serious cases, it will crack and fracture, so we must pay attention to it.
Use appropriate operating tools.
Avoid replacing with existing tools, and appropriate tools must be used.
Pay attention to the corrosion of the bearing.Three common maintenance techniques for bearing fatigue failure of SKF rolling mill
When operating Timken bearings, sweat on your hands can be the cause of rust. Pay attention to operate with clean hands and try to wear gloves.Three common maintenance techniques for bearing fatigue failure of SKF rolling mill
Because Timken bearing is a high-precision product, if it is not assembled properly, it is easy to damage the bearing channel and lead to bearing damage. The bearing shall be equipped with a special mold during assembly, which cannot be knocked at will. When pressing the shaft, only the small ring can be stressed, and when pressing the large ring, only the large ring can be stressed. Three common maintenance techniques for bearing fatigue failure of SKF rolling mill
Pneumatic or hydraulic pressure is required during assembly. During press assembly, the upper and lower molds shall be outside the horizontal state. If there is inclination, the bearing channel will be damaged due to stress and the bearing will make a guide sound.Three common maintenance techniques for bearing fatigue failure of SKF rolling mill
When the bearing is installed on the rotor for dynamic balance, it is easy to enter the iron filings generated during dynamic balance into the bearing, so it is necessary to perform dynamic balance before installing Timken bearing.
In order to facilitate assembly, some manufacturers apply some oil or grease in the bearing chamber for lubrication effect during assembly, but it is often difficult for operators to control the amount. Three common maintenance techniques for bearing fatigue failure of SKF rolling mill
If more oil or grease is accumulated in the bearing chamber, it is easy to enter the bearing along the shaft when the bearing rotates. The bearing shall not be coated with oil or grease. If it must be coated, it shall be controlled and there shall be no accumulation in the bearing chamber.Three common maintenance techniques for bearing fatigue failure of SKF rolling mill
The feature of paint rust is that it often occurs in sealed motors. The sound of the motor is very good during assembly, but after it is put in the warehouse for some time, the abnormal noise of the motor becomes very large, and there is serious rust when the bearing is removed.Three common maintenance techniques for bearing fatigue failure of SKF rolling mill
In the past, many manufacturers thought it was the problem of Timken bearing. After our continuous publicity, now the motor factory has realized that it is mainly the problem of insulating paint. This problem is mainly because the acidic substances volatilized from the insulating paint form corrosive substances at a certain temperature and humidity, which corrodes the bearing channel and leads to bearing damage.
At present, the problem can only be to select good insulating paint and assemble after drying and ventilation for a period of time.Three common maintenance techniques for bearing fatigue failure of SKF rolling mill
The service life of the bearing is closely related to manufacturing, assembly and use. It must be done well in each link in order to make the bearing in the running state, so as to prolong the service life of the bearing.Three common maintenance techniques for bearing fatigue failure of SKF rolling mill
Rolling bearings make precision parts, so it is required to be cautious when using them. Since high-performance bearings are used, if they are not used properly, they can not achieve the expected performance effect. Therefore, the following matters should be paid attention to when using Timken bearings:Three common maintenance techniques for bearing fatigue failure of SKF rolling mill
Keep the bearings and their surroundings clean. Even if the invisible smile dust enters the bearing, it will increase the wear, vibration and noise of the bearing.Three common maintenance techniques for bearing fatigue failure of SKF rolling mill
When using and installing, it shall be careful. It is not allowed to punch with force, directly knock the bearing with a hammer, and transfer pressure through the rolling body.Three common maintenance techniques for bearing fatigue failure of SKF rolling mill
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