Failure factors and maintenance measures of Timken imported bearing
nternal factors mainly refer to the three factors that determine the quality of Timken imported bearings, such as structural design, manufacturing process and material quality.Failure factors and maintenance measures of Timken imported bearing
First, the reasonable design and advanced nature of the structure will lead to longer TIMKEN bearing life. The manufacturing of bearings generally goes through multiple processing processes such as forging, heat treatment, turning, grinding and assembly. The rationality, advanced nature and stability of all the processing technologies will also affect the life of TIMKEN imported bearings.Failure factors and maintenance measures of Timken imported bearing
Among them, the heat treatment and grinding processes that affect the quality of Timken imported bearings are often more directly related to the failure of bearings. In recent years, the research on the metamorphic layer of the bearing working surface shows that the grinding process is closely related to the surface quality of Timken imported bearings.Failure factors and maintenance measures of Timken imported bearing
The metallurgical quality of Timken imported bearing materials was once the main factor affecting the early failure of Timken imported rolling bearings. With the development of Metallurgical Technology (such as vacuum degassing of bearing steel), the quality of raw materials has been improved. Failure factors and maintenance measures of Timken imported bearing
The proportion of raw material quality factor in Timken imported bearing failure analysis has decreased significantly, but it is still one of the main influencing factors of Timken imported bearing failure. Proper material selection is still a factor that must be considered in bearing failure analysis.Failure factors and maintenance measures of Timken imported bearing
The main task of Timken imported bearing failure analysis is to find out the main factors causing bearing failure according to a large number of background materials, analysis data and failure forms, so as to put forward targeted improvement measures, prolong the service life of Timken imported bearings and avoid sudden early failure of Timken imported bearings.
For sealed Timken imported bearings, appropriate grease has been filled during production; For the bearing, a sealing device is also set in the main engine to prevent the leakage of lubricating grease.
There is a problem of how much grease should be injected into Timken imported bearings.
Too little grease injection is easy to cause lack of grease or dry friction and affect service life. Excessive grease injection will lead to a large amount of grease leakage, which will not only pollute the environment, but also cause waste. It can be seen that the amount of grease injected into Timken imported bearing is the less the better on the premise of ensuring the full lubrication of Timken imported bearing.
Advantages and disadvantages of grease lubrication under normal working conditions, grease lubrication can be used for most Timken imported bearing applications.Failure factors and maintenance measures of Timken imported bearing
The advantage of grease is that it is easier to retain in Timken imported bearing configuration, especially in applications where the vertical axis or axis is inclined at a certain angle. The grease also has the function of sealing, which can prevent the influence of pollutants, moisture or moisture on Timken imported bearings. However, if there is too much grease, it will lead to the increase of bearing working temperature, especially in the application of high speed. In most cases, the Timken inlet bearing can be completely filled with grease only at the initial stage, while the Timken inlet bearing seat is only filled with an appropriate amount of grease and left with a certain free space. Before fully reaching the working speed, the excess grease must be discharged from the bearing during the running in stage, so that an appropriate amount of grease can be left in the Timken inlet bearing. When the operating temperature drops significantly, it indicates that the grease has run in with the bearing and is evenly distributed in the Timken imported bearing configuration. The so-called constant pressure preload is a method of giving appropriate preparatory load to the bearing by using coil spring and Belleville spring. In use, even if the relative position of the bearing changes, the preloading method. In use, even if there is a change in the relative position of the walking out, the preload can be roughly maintained at a certain level.
Preload line diagram of SKF imported bearing after constant pressure preload. The rigidity of preload spring is usually very small compared with that of bearing. Therefore, the displacement straight line of spring is approximately parallel to the horizontal axis. Therefore, the rigidity of single bearing with constant pressure preload is the same as that of pre applied preload
The rigidity of the single bearing with axial load is roughly the same. Comparison of rigidity between SKF imported bearing and bearing monomer after positioning preload and constant pressure preload.
According to the rigidity comparison of preloading methods, the comparison of positioning preload and constant pressure preload is as follows. After fag bearing installation, in order to check whether the installation is correct, operation inspection shall be carried out. Small machinery can be rotated by hand to confirm whether it rotates smoothly. Failure factors and maintenance measures of Timken imported bearing
The inspection items include poor operation caused by foreign matters, scars and indentation, unstable torque caused by poor installation and poor processing of mounting base, excessive torque caused by too small clearance, installation error and sealing friction, etc. If there is no abnormality, the power operation can be started.
Large machinery cannot rotate manually, so the power shall be cut off immediately after no-load start, and the machinery idles. Check whether there is vibration, noise, contact of rotating parts, etc. after confirming that there is no abnormality, enter the power operation.Failure factors and maintenance measures of Timken imported bearing
Power operation, starting from no-load and low speed, slowly increase to the rated operation under the specified conditions. During the test run, the inspection items are whether there is abnormal sound, FAG bearing temperature change, lubricant leakage or discoloration, etc. If any abnormality is found, stop the operation immediately, check the machinery, and remove the bearing for inspection if necessary.Failure factors and maintenance measures of Timken imported bearing
Fag bearing temperature can generally be inferred from the external temperature of bearing pedestal. However, it is more accurate to directly measure the temperature of the bearing outer ring by using the oil hole. The bearing temperature rises gradually from the beginning of operation, and the temperature is usually stable after 1 ~ 2 hours. Failure factors and maintenance measures of Timken imported bearing
If the bearing is not installed properly, the temperature will rise sharply, resulting in abnormal high temperature. The reasons are too much lubricant, too small bearing clearance, poor installation, excessive friction of sealing device, etc. In the case of high-speed rotation, the wrong selection of fag bearing structure and lubrication mode is also the reason.Failure factors and maintenance measures of Timken imported bearing
The rotation of fag bearing is checked with stethoscope, and there are strong metal noise, abnormal sound, irregular sound and other indications of abnormality. The reasons are poor lubrication, poor accuracy of shaft or bearing seat, bearing damage, foreign matter intrusion, etc. Failure factors and maintenance measures of Timken imported bearing
Using lead pressure method to detect the clearance of NTN imported bearing is more accurate than using feeler gauge, but it is more troublesome. The aluminum wire used for testing should be soft, and the diameter should not be too large or too small. The ideal diameter is 1.5 ~ 2 times of the gap. In practical work, soft lead wire is usually used for testing.Failure factors and maintenance measures of Timken imported bearing
During the inspection, first open the NTN inlet bearing cover, select the lead wire with appropriate diameter, cut it into a small section with a length of 15 ~ 40mm, put it on the journal and the interface between the upper and lower bearings, cover the bearing cover, tighten the fixing bolts according to the specified torque, then loosen the bolts, remove the bearing cover, detect the thickness of the flattened lead wire with a micrometer, and calculate the average value of the top clearance of the NTN inlet bearing.Failure factors and maintenance measures of Timken imported bearing
If the top clearance is too small, a pad can be added on the joint surface of the upper and lower tiles. If it is too large, the pad shall be reduced, scraped or the tile shall be poured again.Failure factors and maintenance measures of Timken imported bearing
Adjustment of bearing bush tightening force: in order to prevent the possible rotation and axial movement of the bearing bush during the working process, in addition to the interference and stop parts, the bearing bush must also be compressed with NTN imported bearing cover. The measurement method is the same as the top clearance measurement method. In addition to measuring the thickness of soft lead wire, the bearing bush tightening force can be calculated (expressed by the elastic deformation of the bearing bush after compression)
Generally, the pressing force of bearing bush is 0.02 ~ 0.04 mm. If the pressing force does not meet the standard, it can be adjusted by increasing or decreasing the thickness of the gasket at the joint surface of NTN inlet bearing and bearing seat, and the pad back is not allowed to be padded.Failure factors and maintenance measures of Timken imported bearing
In addition to radial clearance, the sliding NTN inlet bearing should also ensure axial clearance. When detecting the axial clearance, move the shaft to an extreme position, and then measure the displacement of the shaft from one extreme position to another with a feeler gauge or dial indicator, that is, the axial clearance.Failure factors and maintenance measures of Timken imported bearing
When the clearance of sliding NTN inlet bearing does not meet the regulations, it shall be adjusted. Split bearings often use shims to adjust the radial clearance (top clearance). Koyo imported bearings show strong regularity and good repeatability in their use. When the normal high-quality bearing (Koyo imported bearing) is used at the beginning, the vibration and noise are relatively small, but the spectrum is scattered and the amplitude is small, which may be caused by some defects in the manufacturing process, such as surface burrs.Failure factors and maintenance measures of Timken imported 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 bearing state is very stable and enters the stable working period.Failure factors and maintenance measures of Timken imported bearing
After continued operation and entering the later stage of use, the vibration and noise of Koyo imported bearing began to increase, and sometimes abnormal sound appeared, but the vibration increased slowly. At this time, the bearing kurtosis began to suddenly reach a certain value. We believe that at this time, the imported bearing of Koyo shows initial failure.Failure factors and maintenance measures of Timken imported bearing
At this time, it is required to closely monitor the imported Koyo bearing and pay close attention to its changes. Since then, the bearing kurtosis value 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 bearing kurtosis value also began to increase rapidly. Failure factors and maintenance measures of Timken imported bearing
When both the vibration standard and the kurtosis value also exceeded the normal value (the relative standard of kurtosis available), we believe that the bearing has entered the late fault production, and the equipment needs to be repaired in time, Replace the Koyo imported bearing.Failure factors and maintenance measures of Timken imported bearing
Koyo imported bearings show the characteristics of late failure. The time from serious failure (generally bearing damage, such as shaft holding, burn, sand frame crack, raceway, bead wear, etc.) is usually less than one week. The larger the equipment capacity, the faster the speed, and the shorter the interval. Therefore, in the actual Koyo imported bearing fault diagnosis, once the late fault characteristics are found, the bearing fault should be determined and the maintenance should be arranged as soon as possible.Failure factors and maintenance measures of Timken imported bearing
Although the bearing is metal, it will also be damaged. No matter what hard material it is, it will be damaged, but the degree of damage is different. We all know that Timken bearings are of good quality and made of good steel. Steel is a very solid material, but it will also be damaged. Failure factors and maintenance measures of Timken imported bearing
Timken bearings run in the machine every day, and it is easy to damage Timken bearings due to constant friction, Therefore, we should also prevent the damage of Timken bearing, maintain the bearing well, and do not use the bearing indiscriminately, causing unnecessary losses to ourselves.Failure factors and maintenance measures of Timken imported bearing
Failure factors and maintenance measures of Timken imported bearing
So how to deal with the bearing damage. If the bearing is used correctly, it can be used until the fatigue life is reached. However, there will be accidental and premature damage, which can not be resistant to use. This early damage, as opposed to fatigue life, is the quality service limit known as failure or accident. Most of them are caused by careless installation, use and lubrication, foreign matters invading from the outside, and insufficient research on the thermal effects of shafts and shells. Failure factors and maintenance measures of Timken imported bearing
As for the damage state of the bearing, such as the clamping damage of the ring and retaining edge of the roller bearing, these reasons can be considered. These reasons also coincide with insufficient lubricant, unfitness, defects of the oil supply and drainage structure, invasion of foreign matters, bearing installation error and excessive deflection of the shaft. Failure factors and maintenance measures of Timken imported bearing
Therefore, only investigating the bearing damage, it is difficult to know the real cause of the damage. However, if you know the use machinery, service conditions, structure around the bearing, understand the situation before and after the accident, and investigate the damage state of the bearing and several causes, you can prevent similar accidents from happening again.Failure factors and maintenance measures of Timken imported bearing
Through the introduction, it can be found that the correct use will not cause damage to the bearing. Incorrect installation, external immersion in foreign matters and improper lubrication are the main causes of bearing damage. Therefore, enterprises should pay more attention to these aspects in the use of bearings to prevent bearing damage and affect the work.Failure factors and maintenance measures of Timken imported bearing
If a deeper compressive stress layer occurs in some way, for corrosion stress. It can offset the tensile stress of the workpiece, greatly reduce the harm of corrosion fatigue, and strive to change the induction heating. When the sensor contacts the workpiece, its resistance to the ground drops rapidly. At this time, the sudden drop of resistance can be used as an electrical signal. The induction heating power source can be cut off immediately through the transistor switch line, and an alarm signal will be sent at the same time. After the fault is eliminated, the power will be sent to restore the induction heating of the workpiece. Failure factors and maintenance measures of Timken imported bearing
The dimensional accuracy and surface quality of imported bearings shall be as good as possible to prevent dust from mixing in during assembly. The hardened layer depth of frequency induction heating quenching is 37mm, the hardened layer depth is ≥ 2.3mm, the hardened layer depth of 110mm in the West and 120ram are ≥ 4mm and ≥ 6ram respectively. Failure factors and maintenance measures of Timken imported bearing
During production, it is found that the half shafts of several drive axles are 120mm, resulting in uneven structure of bucket teeth, low hardness of inserts and no strengthening effect. On the contrary, it is lower than the strength and hardness of the base body, and poor wear resistance. The overall strength of bucket teeth is lack and poor wear resistance. The excavator is under severe working conditions.Failure factors and maintenance measures of Timken imported bearing
There are often multiple fracture crack sources, most of which originate from the inner surface of NSK bearing water jacket. Black corrosion appears in the crack source area, but the morphological characteristics of fatigue arc band are not obvious and clear.Failure factors and maintenance measures of Timken imported bearing
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