Selection and control of fag bearing housing tolerances
Fag bearing shall rotate flexibly without blocking feeling after being pressed into the bearing. If there is obvious inflexible rotation, it indicates that the size of the shaft is too large and the tolerance should be reduced. If the fag bearing is pressed into the shaft and rotates by hand with an obvious “rusty” feeling, it may be that the tolerance of the shaft is too large or the roundness of the shaft is not good.
Therefore, when controlling the tolerance of shaft and bearing chamber, it is also necessary to control the roundness. At present, many domestic manufacturers only control the tolerance, not the roundness.What should be paid attention to when using fag bearing
Fag bearing assembly method
Because fag bearing is a high-precision product, if it is not assembled properly, it is easy to damage the fag bearing channel, resulting in the damage of fag bearing. Fag bearing shall be equipped with a special mold during assembly, which can not be knocked at will. When pressing the shaft, it can only be stressed by a small ring, and when pressing a large ring, it can only be stressed by a large ring.
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 fag bearing channel will be damaged due to stress and the fag bearing will make a sound.What should be paid attention to when using fag bearing
Prevention of foreign matters during assembly
When fag bearing is installed on the rotor for dynamic balance, it is easy to enter the iron filings generated during dynamic balance into fag bearing. Therefore, dynamic balance is performed before fag bearing is installed. 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.What should be paid attention to when using fag bearing
If there is a large amount of oil or grease in the fag bearing chamber, it is easy to enter the fag bearing along the shaft when the fag bearing rotates. In Japan, FAG bearing chamber should not be coated with oil or grease. If it must be coated, it should be controlled and there should be no accumulation in the bearing chamber.What should be paid attention to when using fag bearing
Prevention of paint rust
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 removing fag bearings. In the past, many manufacturers thought it was the problem of fag bearing. What should be paid attention to when using fag bearing
After our continuous publicity, the motor factory has realized that the main problem is the insulating paint. The main reason for this problem is that the acidic substances volatilized from the insulating paint form corrosive substances at a certain temperature and humidity, which corrodes the fag bearing channel and leads to the damage of fag bearing. At present, the problem can only be to select good insulating paint and assemble after drying and ventilation for a period of time.What should be paid attention to when using fag bearing
The service life of fag bearing is closely related to manufacturing, assembly and use. Only by doing well in each link can fag bearing be in the running state, so as to prolong the service life of fag bearing.
After moving for a period of time, the vibration and noise maintain a certain level, and the spectrum is very single, with only one or two times the frequency. The frequency spectrum above three times of power frequency rarely appears, and the state of fag bearing is very stable and enters the stable working period.
After continued operation and entering the later stage of use, the vibration and noise of fag bearing began to increase, and sometimes abnormal sound appeared, but the change of vibration increase was slow. At this time, the kurtosis value of fag bearing began to suddenly reach a certain value. We believe that fag bearing shows initial failure at this time.
At this time, it is required to closely monitor the fag bearing and pay close attention to its changes. Since then, the kurtosis value of fag bearing began to decline rapidly and close to the normal value, while the vibration and noise began to increase significantly, and the increase amplitude began to accelerate.
When the vibration exceeded the vibration standard (such as ISO2372 standard), the kurtosis value of fag bearing also began to increase rapidly. When both the vibration standard and the kurtosis value also exceeded the normal value (the relative kurtosis standard can be used), the fag bearing has entered the late fault production, and the equipment needs to be repaired in time, Replace the rolling fag bearing.
When identifying SKF Bearing, pay attention to:What should be paid attention to when using fag bearing
Fag bearing shows the characteristics of late failure. The time from the occurrence of serious failure (generally fag bearing damage, such as shaft holding, burn, sand frame crack, raceway, bead wear, etc.) is mostly less than one week. The larger the equipment capacity, the faster the speed, and the shorter the interval. Therefore, in the actual rolling fag bearing fault diagnosis, once the late fault characteristics are found, the fag bearing should be determined to have a fault and the maintenance should be arranged as soon as possible.
Whether the outer packaging is clear: generally, the brands of the main factory have their own special designers to design the outer packaging, and arrange the factories with qualified production conditions for production. Therefore, the packaging is very clear from line to color block – unambiguous.
Whether the steel seal words are clear: the SKF Bearing body will be printed with brand words, labels, etc. The font is very small, but most of the products produced by the original factory use steel printing technology, and they are pressed before overheating treatment. What should be paid attention to when using fag bearing
Therefore, although the font is small, it is concave – deep and very clear. The font of counterfeit products is not only fuzzy, but also floating on the surface due to the rough printing technology. Some of them can even be easily erased by hand.What should be paid attention to when using fag bearing
Whether there is any noise: hold the inner sleeve of SKF Bearing with your left hand, and turn the outer sleeve with your right hand to hear whether there is any noise. Due to the backward production conditions of most counterfeit products and the complete manual workshop operation, it is inevitable that impurities such as sand will be mixed in the production process and hidden in the SKF Bearing, so it will make a noise when rotating. This is a big difference from the factory brand that strictly implements production standards and operates with machines.
Whether there is muddy oil on the surface: this should be paid special attention when purchasing SKF bearings. As the current domestic antirust technology is not particularly good, it is easy to leave thick oil traces when antirust the SKF Bearing body, which is viscous when holding it in your hand. However, there is almost no trace of antirust oil on the original SKF Bearing in foreign countries. However, a particularly careful expert said that the SKF Bearing smells like a smell. It must be under antirust oil, but it can’t be seen.
Whether the chamfer is uniform: the so-called chamfer of SKF Bearing, that is, the junction of horizontal and vertical surfaces. Due to the limitation of production technology, the fake SKF Bearing is not handled satisfactorily at these corners.
Use a sound detector to check the size and sound quality of the rolling sound of the using fag bearing
The inspection items include rolling sound, vibration, temperature, lubrication status, etc. the specific conditions are as follows:What should be paid attention to when using fag bearing
Even if the bearing has slight peeling and other damage, it will produce abnormal sound and irregular sound, which can be distinguished by the sound detector.What should be paid attention to when using fag bearing
Bearing vibration is very sensitive to bearing damage, such as peeling, indentation, corrosion, crack, wear, etc., which will be reflected in bearing vibration measurement. Therefore, the vibration can be measured by using special bearing vibration measuring instrument (frequency analyzer, etc.), and the specific situation of abnormality can be inferred through frequency analysis. What should be paid attention to when using fag bearing
The measured values are different due 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 to determine the judgment standard.What should be paid attention to when using fag bearing
The temperature of the bearing can be inferred from the temperature outside the bearing chamber. It is more appropriate if the oil hole can be used to directly measure the temperature of the outer ring of the bearing. Usually, the temperature of the bearing rises slowly with the start of operation and reaches a stable state after 1-2 hours.
The normal temperature of the bearing varies with the heat capacity, heat dissipation, speed and load of the machine. If the inspection and fault handling, lubrication and installation parts of NTN bearing are appropriate during operation, the bearing temperature will rise sharply and abnormal high temperature will occur. At this time, the operation must be stopped and necessary preventive measures must be taken.What should be paid attention to when using fag bearing
When disassembling and inspecting the damaged NTN bearing, the fault and damage cause of the bearing can be judged according to the damage of the bearing.What should be paid attention to when using fag bearing
The bearing rolling element and the inner and outer race raceways bear the action of periodic fluctuating load, resulting in periodic contact stress. When the number of stress cycles reaches a certain value, fatigue spalling will occur on the working surface of rolling element or inner and outer race raceway.What should be paid attention to when using fag bearing
If the load of the bearing is too large, it will aggravate this fatigue. In addition, improper bearing installation and shaft bending will also produce raceway spalling. The fatigue spalling of bearing raceway will reduce the operation accuracy of shaft and cause vibration and noise of mechanism.What should be paid attention to when using fag bearing
There is a return fire color on the raceway and rolling element of the burned bearing. The causes of burns are generally insufficient lubrication, unqualified or deteriorated lubricating oil quality, and too tight bearing assembly.What should be paid attention to when using fag bearing
Uneven pits appear on the contact surface between the raceway and the roller of the bearing, indicating that the bearing has plastic deformation. The reason is that under the action of large static load or impact load, the local stress on the working surface of the bearing exceeds the yield limit of the material, which generally occurs on the bearing rotating at low speed.What should be paid attention to when using fag bearing
The reasons for the cracks of the bearing race may be that the bearing fits too tightly, the outer or inner ring of the bearing is loose, the containing parts of the bearing are deformed, the surface processing of the installed bearing is poor, etc.What should be paid attention to when using fag bearing
The reasons are insufficient lubrication, broken rolling element, seat ring skew, etc.What should be paid attention to when using fag bearing
The possible cause is that the rolling element is stuck in the cage or the lubrication is insufficient.What should be paid attention to when using fag bearing
It may be that foreign matters fall into the seat ring, insufficient lubricating oil or inappropriate lubricating oil brand.What should be paid attention to when using fag bearing
The main factors affecting the damage of NTN bearing are: load, lubrication, assembly, environmental conditions, material or manufacturing precision fag bearing
During the fag bearing.
the inspection items include rolling sound, vibration, temperature, lubrication status, etc. the specific conditions are as follows:
Use a sound detector to check the size and sound quality of the rolling sound of the running bearing. Even if the bearing has slight peeling and other damage, it will produce abnormal sound and irregular sound, which can be distinguished by the sound detector.
Bearing vibration is very sensitive to bearing damage, such as peeling, indentation, corrosion, crack, wear, etc., which will be reflected in bearing vibration measurement. Therefore, the vibration can be measured by using special bearing vibration measuring instrument (frequency analyzer, etc.), and the specific situation of abnormality can be inferred through frequency analysis.
The measured values are different due 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 to determine the judgment standard.
The temperature of the bearing can be inferred from the temperature outside the bearing chamber. It is more appropriate if the oil hole can be used to directly measure the temperature of the outer ring of the bearing. Usually, the temperature of the bearing rises slowly with the start of operation and reaches a stable state after 1-2 hours.
The normal temperature of the bearing varies with the heat capacity, heat dissipation, speed and load of the machine. If the inspection and fault handling, lubrication and installation parts of NTN bearing are appropriate during operation, the bearing temperature will rise sharply and abnormal high temperature will occur. At this time, the operation must be stopped and necessary preventive measures must be taken.
When disassembling and inspecting the damaged NTN bearing, the fault and damage cause of the bearing can be judged according to the damage of the bearing.
The bearing rolling element and the inner and outer race raceways bear the action of periodic fluctuating load, resulting in periodic contact stress. When the number of stress cycles reaches a certain value, fatigue spalling will occur on the working surface of rolling element or inner and outer race raceway.
If the load of the bearing is too large, it will aggravate this fatigue. In addition, improper bearing installation and shaft bending will also produce raceway spalling. The fatigue spalling of the bearing raceway will reduce the operation accuracy of the shaft and cause vibration and noise of the mechanism
Ina bearing is an international well-known brand bearing with a wide range of uses.
Size, direction and nature of load: ball bearing is suitable for light load, and roller bearing is suitable for heavy load and impact load. When the rolling shaft bears pure axial load, thrust bearing is generally selected; When the rolling shaft bears pure radial load, deep groove ball bearing or short cylindrical roller bearing is generally selected;
When the rolling shaft bears pure radial load and small axial load, deep groove ball bearing, angular contact ball bearing, tapered roller bearing, self-aligning ball or self-aligning roller bearing can be selected; When the axial load is large, the angular contact ball bearing and tapered roller bearing with large contact angle can be selected, or the combination of radial bearing and thrust bearing can be selected, which is especially suitable for extremely high axial load or special requirements for large axial rigidity.
Allowable speed: it varies greatly due to different types of imported bearings. In general, bearings with low friction and low heat generation are suitable for high speed. The rolling bearing shall be designed to work under the condition of lower than its limit speed.
Rigidity: when the bearing bears load, the contact between the bearing ring and the rolling element will produce elastic deformation. The amount of deformation is proportional to the load, and its ratio determines the rigidity of the bearing. Generally, the rigidity of the bearing can be improved through the preloading of the bearing; In addition, in the bearing support design, considering the combination and arrangement of bearings can also improve the support stiffness of bearings.
Centering performance and installation error: after the bearing is installed in the working position, it is often installed and positioned poorly due to manufacturing error. At this time, the bearing is often subjected to excessive load due to shaft deflection and thermal expansion, resulting in early damage. Self aligning bearing can overcome the defects caused by installation errors by itself, so it is a bearing suitable for this kind of purpose.
Installation and disassembly: tapered roller bearing, needle roller bearing and tapered roller bearing belong to the type of bearing with separable inner and outer rings (i.e. the so-called separated bearing), which is convenient for installation and disassembly.
Users will inevitably encounter noise from the bearing in the process of use. So how to reduce the noise of INA Bearing? Let’s give you a brief introduction:
Adding some chemical additives to the lubricant of INA Bearing by using chemical additives can reduce the bearing noise. For example, a low-noise grease containing noise reduction additives produced by a factory in Tianjin can reduce the bearing noise by 3.9 ~ 9.2db from the original basis, which is suitable for use in micro or small bearings.
Good results can be obtained by using vibration absorption or vibration isolation devices to reduce the noise of ina bearings or isolate the noise of bearings, but this often costs a lot in economy. Sometimes, the mechanism becomes larger, the heat dissipation conditions become worse, or it is easy to rust. It should be considered comprehensively in use.
This method can be used only after other measures are taken and the low noise index can not be reached. A simple example is the centripetal ball bearing that bears the thrust instead of the thrust bearing at high speed. It can be sleeved with a plastic jacket filled with antirust lubricating oil on its outer ring. The thrust bearing with housing or general thrust bearing can be inlaid with the same plastic sleeve in its inner hole or outer circle if allowed, but the control can not rub or interfere with adjacent parts during rotation.
This method has a certain silencing effect. Another example is to add an intermediate sleeve between the bearing and the seat hole, which can attenuate the vibration force transmitted by the rotating system to the bearing seat, but this requires proper allocation, otherwise the opposite effect may occur.
Another example is the use of sound absorption and sound insulation cover to completely close the bearing system with noise or as close as possible. The inner part of the noise reduction cover is glass fiber or polyurethane foam plastic, and the inner surface is 0.6- LMM thick steel plate, which is uniformly distributed on the surface φ 1.2-1.5mm small through hole, the total area of which accounts for about 25% ~ 30% of the whole inner surface, and the outer surface is 2mm thick steel plate.
Here, glass fiber or foam plastic is used to eliminate higher frequency noise, the inner surface with small holes is used to eliminate lower frequency noise, and the thick steel plate on the outer surface is used to isolate the external transmission of noise.
The method of changing the speed of the corresponding part of the main engine ina bearing noise is not very sensitive to the load, but it is very sensitive to the speed. If conditions permit, reduce the speed and increase the torque to achieve the same working purpose, but reduce the noise.
[example] in order to reduce the noise of the oil pump system, the original oil pump with a flow of 10L / min at a motor speed of 1430r / min is changed to a motor with a speed of 710r / min and equipped with a larger oil pump to obtain the same flow. After that, the noise of the oil pump itself, the oil pump bearing and the oil pump motor bearing is significantly reduced, but the space occupied by the whole mechanism is expanded and the cost is increased.
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