Analysis of detection technology of NTN imported bearing and shaft fit
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. Analysis of detection technology of NTN imported bearing and shaft fit
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.Analysis of detection technology of NTN imported bearing and shaft fit
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.Analysis of detection technology of NTN imported bearing and shaft fit
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.Analysis of detection technology of NTN imported bearing and shaft fit
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. If the bearing is not installed properly, the temperature will rise sharply, resulting in abnormal high temperature.Analysis of detection technology of NTN imported bearing and shaft fit
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.Analysis of detection technology of NTN imported bearing and shaft fit
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. Analysis of detection technology of NTN imported bearing and shaft fit
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.Analysis of detection technology of NTN imported bearing and shaft fit
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.Analysis of detection technology of NTN imported bearing and shaft fit
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.Analysis of detection technology of NTN imported bearing and shaft fit
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).Analysis of detection technology of NTN imported bearing and shaft fit
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.Analysis of detection technology of NTN imported bearing and shaft fit
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.Analysis of detection technology of NTN imported bearing and shaft fit
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. Analysis of detection technology of NTN imported bearing and shaft fit
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.Analysis of detection technology of NTN imported bearing and shaft fit
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.Analysis of detection technology of NTN imported bearing and shaft fit
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.Analysis of detection technology of NTN imported bearing and shaft fit
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. Analysis of detection technology of NTN imported bearing and shaft fitAnalysis of detection technology of NTN imported bearing and shaft fit
When the vibration exceeded the vibration standard (such as ISO2372 standard), the bearing kurtosis value also began to increase rapidly. 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.Analysis of detection technology of NTN imported bearing and shaft fit
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. Analysis of detection technology of NTN imported bearing and shaft fit
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. 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.Analysis of detection technology of NTN imported bearing and shaft fit
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. Analysis of detection technology of NTN imported bearing and shaft fit
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. 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.Analysis of detection technology of NTN imported bearing and shaft fit
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. Analysis of detection technology of NTN imported bearing and shaft fit
Analysis of detection technology of NTN imported bearing and shaft fit
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, the 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 the recurrence of similar accidents.Analysis of detection technology of NTN imported bearing and shaft fit
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. If a deeper compressive stress layer occurs in some way, for corrosion stress. Analysis of detection technology of NTN imported bearing and shaft fit
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. Analysis of detection technology of NTN imported bearing and shaft fit
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. The dimensional accuracy and surface quality of imported bearings shall be as good as possible to prevent dust from mixing in during assembly. Analysis of detection technology of NTN imported bearing and shaft fit
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. 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. Analysis of detection technology of NTN imported bearing and shaft fit
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.Analysis of detection technology of NTN imported bearing and shaft fit
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.Analysis of detection technology of NTN imported bearing and shaft fit
INA Bearing uses a cage made of glass fiber reinforced nylon 66, which is suitable for the steady state of working temperature of 120 degrees. Oil is used to lubricate the bearing. If the oil contains additives, it may shorten the life in the cage. When the temperature exceeds 120 ℃, PetroChina will shorten the aging life of the cage. Observation and oil change shall be arranged.Analysis of detection technology of NTN imported bearing and shaft fit
The need for grease filling of sealed bearings and the requirements of contact seal life and allowable temperature.Analysis of detection technology of NTN imported bearing and shaft fit
Cutting set temperature and cutting chip temperature, using the experimental method, through a tool, ina bearing can be used to determine the distribution of heat transfer and theoretical calculation of temperature field.Analysis of detection technology of NTN imported bearing and shaft fit
Sealed ina bearings use specially tested high-quality lithium base grease. This grease can withstand a short period of high temperature of 120 degrees. If the stable temperature is 70 degrees or higher, the service life of standard lithium grease will be shortened.
To always work at high temperatures, you must use a special grease, but also pay attention to the need to use heat-resistant materials for sealing. The temperature of standard contact seal shall not exceed 110 degrees.Analysis of detection technology of NTN imported bearing and shaft fit
If you use a high-temperature sealing composite, then you should consider that this very effective fluorine-containing material is more than 300 degrees, which will release gases and smoke harmful to health. Especially in the use of dismantling bearing torch, we should pay more attention to this point.Analysis of detection technology of NTN imported bearing and shaft fit
The contact area between INA Bearing workpiece and cutting tool, due to the effect of heat forming hot end temperature, and the end result side of the tool and workpiece, maintains room temperature and forms the cold end of thermocouple. The thermoelectric electromotive force that will be generated by the tool and workpiece in circulation. Analysis of detection technology of NTN imported bearing and shaft fit
Meter or millivolt potential difference, force recording, according to the pre calibrated thermocouple calibration curve tool, INA Bearing cutting temperature, the average contact surface between the tool and the workpiece can be measured by measuring the workpiece.Analysis of detection technology of NTN imported bearing and shaft fit
In order to ensure that the deformation of ina bearing mounting roll is small, the amount of interference can not be too large, which is offset by high-speed centrifugal force and high-temperature thermal expansion, or the surface with normal pressure. Analysis of detection technology of NTN imported bearing and shaft fit
Or surface relaxation, under the premise that the interference amount must be considered, these two factors are carefully calculated under the interference of constant speed and effective amount of high-speed INA Bearing, which may be invalid at room temperature.Analysis of detection technology of NTN imported bearing and shaft fit
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