Causes and treatment measures of peeling and burn of NSK imported bearing
Causes and treatment measures of peeling and burn of NSK imported bearing
2022-05-11
How to reduce NTN bearing failure rate?
How to reduce NTN bearing failure rate?
2022-05-11

Precautions for appearance inspection of Timken bearing

For the riveting or welding quality of the cage, Timken bearing

  • Mainly observe whether the rivet head is offset, skewed, loose Lack of meat or “Double eyelid”, whether the welding position is correct, whether the welding spot is too large or too small, whether the rolling element is stuck due to loose welding or excessive welding, whether the quality of slope pressing, edge trimming, caulking and chiseling of some cages is guaranteed, and whether the rolling element can not fall out of the cage and rotate freely. Precautions for appearance inspection of Timken bearing
  • If these points are unqualified, the noise and rotation accuracy of Timken bearing will be reduced if they are small, and the cage may be scattered and the bearing will be damaged if they are large Cause mechanical failure or accident.Precautions for appearance inspection of Timken bearing
  • Peeling and folding, the local combination of these two defects with the base metal is not strong, and decarburization or carbon deficiency often exist around them to varying degrees. The material is easy to collapse, dent or wear, which is very unfavorable to the service life and accuracy of Timken bearing.Precautions for appearance inspection of Timken bearing
  • Various cracks, such as raw material cracks, forging cracks, heat treatment cracks and grinding cracks, will become the source of stress concentration and expand rapidly in the later operation of Timken bearing, resulting in the rupture of Timken bearing, which has a great impact on the service life and workability of Timken bearing. Precautions for appearance inspection of Timken bearing
  • In fact, for Timken bearings with important applications, Timken bearing factory has conducted 100% magnetic or radiographic inspection on its components. Rust, black skin and pitting. The latter two are defects that are easy to store moisture and dirt, which are easy to develop into rust. Corrosion is the pollution source leading to poor installation, early wear and fatigue. Precautions for appearance inspection of Timken bearing
  • Serious corrosion will scrap Timken bearings. Constant pressure pre tightening is the key point of pre tightening INA Bearing with coil spring, Belleville spring, etc. The rigidity of the preload spring is generally much smaller than that of the INA Bearing, so the relative position of the INA Bearing preloaded under constant pressure will change in use, but the preload is largely stable.Precautions for appearance inspection of Timken bearing
  • When the preload is proportional, the positioning preload has a greater effect on the rigidity growth of INA Bearing, and the rigidity change of INA Bearing has a much smaller effect on the load of INA Bearing.Precautions for appearance inspection of Timken bearing
  • In the use of positioning preload, the axial length difference caused by the temperature difference between the shaft and ina bearing seat, the radial expansion caused by the temperature difference between the inner and outer rings and the displacement caused by load will change the preload; While the constant pressure preload is in use, the change of preload can be ignored carelessly.Precautions for appearance inspection of Timken bearing
  • The radial jacking method is mostly used in tapered bore bearings subjected to radial load. A typical example is the double row precision short cylindrical roller bearing. The nut is used to mediate the axial position of the INA Bearing relative to the sub tapered journal, so that the inner ring has a suitable expansion amount to obtain radial negative clearance. This method is mostly used in machine tool spindle and jet engine.Precautions for appearance inspection of Timken bearing
  • Axial preloading method can be roughly divided into positioning preloading and constant pressure preloading. In positioning preload, ina bearing can decide the size of adjusting bushing or gasket to obtain the appropriate preload; Precautions for appearance inspection of Timken bearing
  • It can also be decided to measure or control the starting friction torque to adjust the appropriate preload; The purpose of preloading can also be realized by directly using the paired duplex ina bearings with preload adjusted in advance. Precautions for appearance inspection of Timken bearing
  • At this time, there is no need for users to mediate. In short, the relative position of ina bearings with axial preload will not change when used. The function of SKF Bearing matching is to make the stationary ring and rotating ring of SKF Bearing consolidate with the stationary part (usually SKF bearing seat) and rotating part (usually shaft) of the installation part respectively, so as to realize the basic task of transmitting load in the rotating state and limiting the position of the motion system relative to the stationary system. Precautions for appearance inspection of Timken bearing
  • On the shaft and in the SKF bearing seat, the rolling SKF Bearing is required to fix its position in three directions: radial, axial and tangent directions. Radial and tangential positioning is realized through tight fit of SKF Bearing Ring, and tight fit is adopted for axial positioning only in a few cases; Generally, axial limit parts, such as end caps and retaining rings, are used to limit the axial position within the clearance range.Precautions for appearance inspection of Timken bearing
Precautions for appearance inspection of Timken bearing

The specific force of positioning preload and constant pressure preload is as follows:Timken bearing

For the riveting or welding quality of the cage,Timken bearing

  • Mainly observe whether the rivet head is offset, skewed, loose Lack of meat or “Double eyelid”, whether the welding position is correct, whether the welding spot is too large or too small, whether the rolling element is stuck due to loose welding or excessive welding, whether the quality of slope pressing, edge trimming, caulking and chiseling of some cages is guaranteed, and whether the rolling element can not fall out of the cage and rotate freely. Precautions for appearance inspection of Timken bearing
  • If these points are unqualified, the noise and rotation accuracy of Timken bearing will be reduced if they are small, and the cage may be scattered and the bearing will be damaged if they are large Cause mechanical failure or accident.Precautions for appearance inspection of Timken bearing
  • Peeling and folding, the local combination of these two defects with the base metal is not strong, and decarburization or carbon deficiency often exist around them to varying degrees. The material is easy to collapse, dent or wear, which is very unfavorable to the service life and accuracy of Timken bearing.Precautions for appearance inspection of Timken bearing
  • Various cracks, such as raw material cracks, forging cracks, heat treatment cracks and grinding cracks, will become the source of stress concentration and expand rapidly in the later operation of Timken bearing, resulting in the rupture of Timken bearing, which has a great impact on the service life and workability of Timken bearing. In fact, for Timken bearings with important applications, Timken bearing factory has conducted 100% magnetic or radiographic inspection on its components. Rust, black skin and pitting. Timken bearing
  • The latter two are defects that are easy to store moisture and dirt, which are easy to develop into rust. Corrosion is the pollution source leading to poor installation, early wear and fatigue. Serious corrosion will scrap Timken bearings. Whether there is muddy oil on the surface: this should be paid special attention when purchasing NTN bearings. Precautions for appearance inspection of Timken bearing
  • Since the current domestic antirust technology is not particularly good, it is easy to leave thick oil traces when antirust the NTN bearing body, which is sticky and thick when holding it in your hand. However, there is almost no trace of antirust oil on the bearings originally imported from abroad. However, a particularly careful expert said that the imported bearings smell like a smell. It must be under antirust oil, but you can’t see it.
  • Whether the chamfer is uniform: the so-called chamfer of NTN bearing, that is, the junction of horizontal and vertical surfaces. Due to the limitation of production technology, the fake NTN bearing of NTN bearing is not handled satisfactorily in these corners. Precautions for appearance inspection of Timken bearing
  • IWhether the steel seal words are clear: brand words, labels, etc. will be printed on the NTN bearing body. 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.Precautions for appearance inspection of Timken 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.Precautions for appearance inspection of Timken bearing
  • Whether there is any noise: hold the inner sleeve of NTN bearing with your left hand, move the outer sleeve with your right hand to rotate it, and listen to NTN bearing for 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 NTN 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

Constant pressure pre tightening is the key point of pre tightening Timken bearing with coil spring.

  • Belleville spring, etc. The rigidity of the preload spring is generally much smaller than that of the INA Bearing, so the relative position of the INA Bearing preloaded under constant pressure will change in use, but the preload is largely stable.

The specific force of positioning preload and constant pressure preload is as follows:Timken bearing

  • When the preload is proportional, the positioning preload has a greater effect on the rigidity growth of INA Bearing, and the rigidity change of INA Bearing has a much smaller effect on the load of INA Bearing.Precautions for appearance inspection of Timken bearing
  • In the use of positioning preload, the axial length difference caused by the temperature difference between the shaft and ina bearing seat, the radial expansion caused by the temperature difference between the inner and outer rings and the displacement caused by load will change the preload; While the constant pressure preload is in use, the change of preload can be ignored carelessly.Precautions for appearance inspection of Timken bearing
  • The radial jacking method is mostly used in tapered bore bearings subjected to radial load. A typical example is the double row precision short cylindrical roller bearing. The nut is used to mediate the axial position of the INA Bearing relative to the sub tapered journal, so that the inner ring has a suitable expansion amount to obtain radial negative clearance. This method is mostly used in machine tool spindle and jet engine.
  • Axial preloading method can be roughly divided into positioning preloading and constant pressure preloading. In positioning preload, ina bearing can decide the size of adjusting bushing or gasket to obtain the appropriate preload; Precautions for appearance inspection of Timken bearing
  • It can also be decided to measure or control the starting friction torque to adjust the appropriate preload; The purpose of preloading can also be realized by directly using the paired duplex ina bearings with preload adjusted in advance. At this time, there is no need for users to mediate. In short, the relative position of ina bearings with axial preload will not change when used.Precautions for appearance inspection of Timken bearing
  • The fit clearance between Koyo bearing and shaft must be appropriate to make the service life of Koyo bearing longer. The radial clearance of Koyo bearing can be detected by the following methods:Precautions for appearance inspection of Timken bearing
  • For Koyo bearings with large diameter, the clearance is large, so it is proposed to use a narrow feeler gauge for direct detection. For Koyo bearing with small diameter, the clearance is small, which is convenient to measure with feeler gauge, but the side clearance of Koyo bearing must be measured with feeler gauge with appropriate thickness.Precautions for appearance inspection of Timken bearing
  • Lead pressure detection method
  • Using lead pressure method to detect the clearance of Koyo bearing is more accurate than using feeler gauge, but it is more troublesome. The aluminum wire used for testing should be soft and moderate in diameter. It 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.Precautions for appearance inspection of Timken bearing
  • During the inspection, first open the Koyo bearing cover, select the lead wire with appropriate diameter, cut it into small sections with a length of 15 ~ 40mm, put it on the journal and the interface between the upper and lower Koyo bearings, cover the Koyo bearing cover, tighten the fixing bolts according to the specified torque, then loosen the bolts, remove the Koyo bearing cover, use a micrometer to detect the thickness of the flattened lead wire, and calculate the average value of the top clearance of the Koyo bearing.Precautions for appearance inspection of Timken 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.Precautions for appearance inspection of Timken bearing
  • Adjustment of bearing bush tightening force: in order to prevent the possible rotation and axial movement of the bearing bush in the working process, in addition to matching the interference and stop parts, the bearing bush must also be compressed with Koyo bearing cover. Precautions for appearance inspection of Timken bearing
  • 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.Precautions for appearance inspection of Timken bearing
  • 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 Koyo bearing and Koyo bearing seat, and the pad back is not allowed to be padded.Precautions for appearance inspection of Timken bearing
  • In addition to radial clearance, sliding Koyo 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. Precautions for appearance inspection of Timken bearing
  • When the clearance of sliding Koyo bearing does not meet the requirements, it shall be adjusted. Split Koyo bearings often use gaskets to adjust the radial clearance.Precautions for appearance inspection of Timken bearing

Race rule detection method Timken bearing

  • How to reduce NTN bearing failure rate? Identification of NTN bearing clearance is the key factor. Clearance is the moving distance of one NTN bearing ring relative to another NTN bearing ring. If the clearance value does not meet the technical standard, it will affect the reasonable distribution of load between rolling elements and reduce the rotation accuracy and service life of NTN bearing.
  • The commonly used measurement methods of NTN bearing clearance are feeler gauge inspection method and lead wire pressing inspection method, but these two methods make the detection rate of unqualified NTN bearing low and time-consuming. Fix the inner ring of the tested NTN bearing with the fixing seat of the inner ring of the NTN bearing, and measure the large amount of movement of the outer ring of the tested NTN bearing along the radial direction, so as to measure the clearance value of the NTN bearing. 
  • The measuring instrument is composed of base, fixing seat (upper and lower) of NTN bearing inner ring, lock nut, dial gauge, magnetic gauge seat, gauge frame and other components. When in use, place the tested NTN bearing flat in the fixed seat of the inner ring of the NTN bearing, tighten the lock nut to fix the inner ring of the tested NTN bearing, and then fix the dial gauge on the center line of the base of the measuring tool with the magnetic gauge base and gauge frame to make the gauge tip contact and vertical with the surface of the outer ring of the tested NTN bearing, and push the outer ring of the NTN bearing back by hand. 
  • At this time, the swing range of the pointer of the dial gauge is the clearance value of the tested NTN bearing. Ina bearing is magnetized, that is, INA Bearing has residual magnetism. The residual magnetism of INA Bearing has a great influence on the service life of INA Bearing. INA Bearing with residual magnetic flux is not easy to clean the metal powder remaining on the working surface of INA Bearing, and even the iron powder produced in the operation of some equipment can be adsorbed on the working surface of INA Bearing, which will accelerate the wear of INA Bearing and reduce the service life of INA Bearing.
  • The reason for the residual magnetism of ina bearing is that with the continuous innovation of INA Bearing processing technology, the magnetic clamping process has been widely used for INA Bearing parts, such as the welding and electric riveting process of electromagnetic centerless fixture and cage, which will produce a magnetic field for ina bearing or other parts. 
  • Although the parts are demagnetized after processing, there may be missing demagnetization or residual magnetism due to improper demagnetization operation. INA Bearing shall be demagnetized before assembly and finished product demagnetization after assembly. The residual magnetic intensity of INA Bearing shall be less than the standard specified in the finished product inspection of INA Bearing.
  • The finished ina bearing is generally far away from the magnetic field and is rarely magnetized. If the ina bearing is stored in an inappropriate position before installation and is magnetized in contact with other magnetic products, or when the product is in use due to the current passing through the INA Bearing, the INA Bearing may be magnetized or damaged by electric corrosion. High speed, overload and insufficient lubrication will not magnetize the INA Bearing, but will make the working surface of the INA Bearing excessively tired and fail.
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