Key points and fault causes of fag bearing operation inspection
Key points and fault causes of fag bearing operation inspection
2022年5月6日
Estimation method of fatigue life of NTN bearing
Estimation method of fatigue life of NTN bearing
2022年5月8日

Impact of vibration on imported Koyo bearings

High temperature on imported Koyo bearings

  • In normal use, vibration is very sensitive to bearing damage. Peeling, indentation, corrosion, crack, wear and so on will be reflected in bearing vibration measurement. Therefore, the magnitude of vibration can be measured by using a special bearing vibration meter (frequency analyzer, etc.), and the specific situation of abnormality can not be inferred through frequency division. Impact of vibration on imported Koyo bearings
  • 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.Impact of vibration on imported Koyo bearings
  • High temperature often indicates that the imported bearing of Koyo is in abnormal condition. High temperature is also harmful to the lubricant of the bearing. Sometimes bearing overheating can be attributed to the lubricant of the bearing. Impact of vibration on imported Koyo bearings
  • If the temperature of the bearing exceeds 125 ℃ for a long time, the service life of the bearing will be reduced. The causes of high temperature bearings include insufficient or excessive lubrication and lubricant. It contains impurities, excessive load, bearing ring damage, insufficient clearance, high friction caused by oil seal, etc.Impact of vibration on imported Koyo bearings
  • In the process of using Koyo imported bearings, it is easy to see the phenomenon of temperature rise. When the bearing temperature rises, first judge whether there is misoperation. If it does rise, do the following:Impact of vibration on imported Koyo bearings
  • Check whether the cooling water pressure, water flow and pipeline system are normal. If the water pressure is low, the filter may be blocked and cannot be handled in time, it can be shut down for treatment. When it is confirmed that it can work, it can be put into use.Impact of vibration on imported Koyo bearings
  • Check the oil pressure of the governor. If the oil pressure is low, the cooling water hydraulic valve may be closed.
  • Check whether the imported bearing of Koyo has abnormal sound and whether the bearing swing is abnormal.
  • Take an oil sample to observe whether the oil color has changed, and test to see whether it has deteriorated. If the deterioration is confirmed, stop the machine and replace it with new oil.Impact of vibration on imported Koyo bearings
  • Check whether the oil level of the oil gauge is normal. If not, check whether the oil drain valve of the oil tank is tightly closed. If it has been closed tightly, oil shall be added. If it is oil leakage from the sealant pad, it shall be shut down for treatment.Impact of vibration on imported Koyo bearings
  • Vibration is quite sensitive to the damage of Koyo imported bearings. Peeling, indentation, corrosion, crack and wear will be reflected in the bearing vibration measurement. Therefore, the magnitude of vibration can be measured by using a special bearing vibration meter (frequency analyzer, etc.), and the specific situation of abnormality can not be inferred through frequency division. Impact of vibration on imported Koyo bearings
  • 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.Impact of vibration on imported Koyo bearings
  • Let’s take a look at the impact of temperature on the bearing.

  • High temperature often indicates that the imported bearing of Koyo is in an abnormal situation. High temperature is also harmful to the lubricant of the bearing. Sometimes bearing overheating can be attributed to the lubricant of the bearing. Impact of vibration on imported Koyo bearings
  • If the temperature exceeds 125 ℃ for a long time, the service life of the bearing can be reduced. The causes of high temperature bearings include insufficient or excessive lubrication and lubricant. It contains impurities, excessive load, bearing ring damage, insufficient clearance, high friction caused by oil seal, etc.Impact of vibration on imported Koyo bearings
  • Therefore, it is necessary to continuously monitor the temperature of Koyo imported bearing, whether it is measuring the bearing itself or other important parts. If the operating conditions remain unchanged, any temperature change can indicate that a fault has occurred.Impact of vibration on imported Koyo bearings
  • The periodic measurement of the bearing temperature imported by Koyo can be carried out with the help of a thermometer, such as a digital thermometer, which can accurately measure the bearing temperature and display it in units of ℃ or Fahrenheit. Important bearing means that when it is damaged, it will cause equipment shutdown. Therefore, this kind of bearing should be equipped with temperature detector.
  • Size limitations. Generally, the space where NTN bearings can be installed is limited. In most cases, the shaft diameter (or bearing inner diameter) is limited by mechanical design or other design. Therefore, the selection of bearing type and size is determined according to the inner diameter of the bearing. Therefore, the main dimension tables of standard bearings are compiled according to the inner diameter dimensions of international standards.Impact of vibration on imported Koyo bearings
  • Cleaning: except for the sealed bearing with double-sided cover, the other bearings are added with antirust oil when leaving the factory. They should be cleaned before use. Usually, immerse the bearing in gasoline mixed with 8-10% mineral oil, hold the inner ring with one hand and rotate the outer ring with the other hand to wash the antirust agent on the bearing surface. The cleaned bearing can not rotate again. After the gasoline volatilizes, inject lubricating oil or grease. Do not stick dust, moisture and hand sweat, so as not to affect the rotation accuracy and rust.Impact of vibration on imported Koyo bearings
  • Loading and unloading: the installed shaft or hole shall be smooth and free of burrs. Carefully measure whether the diameter of the shaft or hole meets the standard, and recognize the INA Bearing datum plane. For the bearing installed on the shaft, the force is only allowed to act on the inner ring. For the bearing installed in the hole, the force is on the outer ring, and the force shall be evenly distributed on the circumference of the end face of the ferrule. Do not hit it with force on one side to avoid skew bite.Impact of vibration on imported Koyo bearings
  •  Load and unload the bearing with large interference, The bearing must be preheated with the heating temperature between 90-100 ℃. Pay more attention to double row spherical roller bearings and single row tapered bearings, because the inner circle retaining edge is very thin and the hole is easy to be broken if you are not careful.
  • Inspection: INA Bearing shall rotate flexibly without stagnation after installation. In addition, the dimensional accuracy and rotation accuracy of the bearing have been checked before leaving the factory, which can ensure the quality. The marks on the inner and outer rings of the bearing and the black on the chamfer of the bearing ring are caused by the process and inspection methods to ensure the quality.
  •  It is purely normal and does not affect the product quality. In the grinding process, the surface layer of the workpiece will be affected by the cutting force, compression force and friction force of the grinding wheel. In particular, the role of the latter two makes the surface layer of the workpiece form a highly directional plastic deformation layer and work hardening layer. These metamorphic layers will inevitably affect the change of residual NSK inlet bearing stress in the surface layer.
  • Cold plastic deformation layer
  • In the grinding process, each moment of abrasive grain is equivalent to a cutting edge. However, in many cases, the rake angle of the cutting edge is negative. In addition to the cutting effect, the abrasive particles make the workpiece surface bear the extrusion effect (ploughing effect), leaving an obvious plastic deformation layer on the workpiece surface. The deformation degree of this deformation layer will increase with the blunt degree of grinding wheel and the increase of grinding feed.
  • The instantaneous temperature formed by grinding heat on the working surface makes the elastic limit of the workpiece surface layer at a certain depth drop sharply, even to the extent that the elasticity disappears.
  •  At this time, the free extension of the working surface layer caused by the grinding force, especially the compression force and friction force, is limited by the base metal, and the surface is compressed (more plough), resulting in plastic deformation in the surface layer. High temperature plastic deformation increases with the increase of workpiece surface temperature under the condition of unchanged grinding process.
  • NSK imported bearing work hardening layer
  • Sometimes, it can be found that the hardness of the surface layer increases due to machining deformation by microhardness method and metallographic method.
  • In addition to grinding, if the decarburized layer on the surface caused by casting and heat treatment heating is not completely removed in subsequent processing, it will also cause surface softening and deterioration and contribute to the early failure of the bearing.

Thermoplastic deformation (or high temperature deformation) layer of NSK imported bearing

  • In the grinding process of SKF imported bearings, a large amount of energy is consumed in the contact area between the grinding wheel and the workpiece, resulting in a large amount of grinding heat, resulting in local instantaneous high temperature in the grinding area. Impact of vibration on imported Koyo bearings
  • It can be found that the instantaneous temperature in the grinding area can be as high as 1000 ~ 1500 ℃ in 0.1 ~ 0.001ms. Such instantaneous high temperature is enough to make the surface layer at a certain depth of the working surface produce high-temperature oxidation, amorphous structure, high-temperature tempering, secondary quenching, and even burn cracking.Impact of vibration on imported Koyo bearings
  • SKF imported bearing surface oxide layer
  • Under the action of instantaneous high temperature, the steel surface reacts with oxygen in the air to form an extremely thin (20 ~ 30nm) thin layer of iron oxide. It should be noted that there is a corresponding relationship between the thickness of oxide layer and the total thickness of surface grinding metamorphic layer. This shows that the thickness of oxide layer is directly related to the grinding process and is an important symbol of grinding quality.Impact of vibration on imported Koyo bearings
  • SKF imported bearing amorphous structure layer
  • When the instantaneous high temperature in the grinding area makes the workpiece surface reach the molten state, the molten metal molecular flow is evenly coated on the working surface and cooled by the base metal at a very fast speed to form a very thin amorphous structure layer. It has high hardness and toughness, but it is only about 10nm, which is easy to be removed in precision grinding.Impact of vibration on imported Koyo bearings
  • SKF imported bearing high temperature tempering layer
  • The instantaneous high temperature in the grinding area can make the surface heated to a certain depth (10 ~ 100nm) higher than the tempering heating temperature of the workpiece. When the austenitizing temperature is not reached, with the increase of the heating temperature, the surface layer by layer will produce the microstructure transformation of re tempering or high-temperature tempering corresponding to the heating temperature, and the hardness will also decrease. The higher the heating temperature, the more severe the decrease of hardness.Impact of vibration on imported Koyo bearings
  • SKF imported bearing two-layer quenching layer
  • When the instantaneous high temperature in the grinding area heats the surface layer of the workpiece above the austenitizing temperature (AC1), the austenitized structure of the layer is re quenched into martensitic structure in the subsequent cooling process. For the workpiece with secondary quenching burn, the high-temperature tempering layer with very low hardness must be under the secondary quenching layer.Impact of vibration on imported Koyo bearings
  • Grinding crack of SKF imported bearing
  • The second quenching burn will change the stress of the surface layer of the workpiece. The secondary quenching zone is under pressure, and there is a large tensile stress in the material of the high-temperature tempering zone below it, which is the place where the crack core may occur. The crack is easy to propagate along the original austenite grain boundary. Severe burns can lead to cracks (mostly cracks) on the whole grinding surface, resulting in scrapping of the workpiece.Impact of vibration on imported Koyo bearings
Impact of vibration on imported Koyo bearings

There are many sizes and forms of scale imported Koyo bearings

  • The load of scale bearings is used in the design of mechanical devices. The nature, size and direction of the load applied to the bearings are changeable. In general, the rated base load is shown on the dimension table. Impact of vibration on imported Koyo bearings
  • However, axial load and radial load are also important factors in selecting suitable bearings. When the size of the ball and needle roller bearing is commensurate, the needle roller bearing usually has high load capacity and bears large vibration and impact load.Impact of vibration on imported Koyo bearings
  • The speed and allowable speed are determined according to the type, size, accuracy, cage type, load, lubrication mode, cooling mode and other factors of NTN bearing. The bearing table lists the allowable speed of the scale precision bearing under oil lubrication and grease lubrication. In general, deep groove ball bearings, self-aligning ball bearings and cylindrical roller bearings are all suitable for high-speed operation.Impact of vibration on imported Koyo bearings
  • NTN bearing tolerance, bearing dimensional accuracy and rotation accuracy are based on ISO and JIS standards. For machines requiring high precision and high-speed operation, it is recommended to use bearings with precision of grade 5 or above. Deep groove ball bearings, centripetal thrust ball bearings or cylindrical roller bearings are suitable for machines with high operation precision. Impact of vibration on imported Koyo bearings
  • Rigidity, when the contact surface between the moving elastic body and the raceway of the bearing is pressed, elastic deformation will occur. Some machines need to minimize elastic deformation. Roller bearings produce less elastic deformation than ball bearings
  • In some cases, NTN bearings are preloaded to increase rigidity. This procedure is usually used for deep groove ball bearings, centripetal thrust ball bearings and tapered roller bearings. Inner and outer ring offset, shaft bending, shaft or bearing housing tolerance change and matching error will lead to inner and outer ring eccentricity. In order to prevent excessive eccentric angle, self-aligning ball bearing, self-aligning roller bearing or self-aligning bearing seat are better choices. Impact of vibration on imported Koyo bearings
  • Voice frequency and torque, dynamic bearings are manufactured according to high-precision standards, so voice and torque are small. Deep groove ball bearings and cylindrical roller bearings are used for occasions with special requirements for low voice and low torque.
  • Installation and disassembly. Some applications require frequent disassembly and installation to ensure that inspection and maintenance can be carried out according to their location. Bearings with separate inner and outer rings, such as cylindrical bearing, needle roller bearing and conical bearing, are very suitable for this occasion. Impact of vibration on imported Koyo bearings
  • With the help of the shaft sleeve, the installation procedure of the taper hole type self-aligning ball bearing and self-aligning roller bearing is also simplified.
  • The so-called burn damage state of NTN bearing refers to that the raceway wheel, rolling element and cage of NTN bearing are heated sharply during rotation until they change color, soften, deposit and damage.Impact of vibration on imported Koyo bearings
  • The second may be excessive load (excessive preloading). Excessive speed. The clearance is too small. Intrusion of water or other foreign matters. If neither of the above two cases is true, the accuracy of the shaft and bearing housing is poor and the deflection of the shaft is large. 
  • Then, the solution is: first, study the lubricant and lubrication method, select the right bearing lubricant and its dosage, and correct the selection of bearing. Study the matching, NTN bearing clearance and preloading, and improve the sealing device. Check the accuracy of the shaft and bearing housing. Of course, if you have it next to you, let him operate it. You can learn from it!
  • It is suggested that when using NTN bearing, attention should be paid to the installation, lubrication, clearance and other links to be as accurate and in place as possible Rolling bearing is a kind of precision basic product. Proper storage and reasonable installation will bring satisfactory results to your use. Due to pollution, corrosion, deformation and other factors, the bearing will affect and destroy the original quality of INA Bearing, which can not achieve your expected use effect.
  • Preservation: INA bearings shall not be exposed in the air. They shall be kept clean and dry in the warehouse. The relative humidity of the inventory air shall not be greater than 55% and the temperature shall be appropriate. The bearings that are not used temporarily after folding shall be coated with oil for sealing. It is also avoided to put it together with corrosive substances such as acid, alkali and chemicals.Impact of vibration on imported Koyo bearings
  • Transportation: the bearing shall be free from deformation and damage due to collision and falling during transportation.Impact of vibration on imported Koyo bearings