Precautions for determining whether ina bearing is overhauled
Precautions for determining whether ina bearing is overhauled
2022-06-02
Factors affecting the tolerance of NTN combined bearings and their solutions
Factors affecting the tolerance of NTN combined bearings and their solutions
2022-06-04

Installation method and precautions of IKO bearing

  • Whether the IKO bearing is installed correctly affects the accuracy, service life and performance. Therefore, the design and assembly department should fully study the installation of IKO bearing. It is hoped that the installation will be carried out according to the operating standards. Items of operating standards are usually as follows:
  • Clean IKO bearing and IKO bearing related parts;Installation method and precautions of IKO bearing
  • Check the size and finish machining of related parts;
  • Installation;

Inspection after IKO bearing is installed

  • It is hoped that the IKO bearing package will be opened just before installation. General grease lubrication, do not clean, directly fill with grease. For lubrication with lubricating oil, it is not necessary to clean in general. However, IKO bearings for instrument or high-speed use should be cleaned with clean oil to remove the rust inhibitor coated on IKO bearings. IKO bearing with rust inhibitor removed is easy to rust, so it can not be placed regardless. Moreover, IKO bearings sealed with grease can be used directly without cleaning.Installation method and precautions of IKO bearing
  • The installation method of IKO bearing varies according to the structure, fit and conditions of IKO bearing. Generally, the inner ring needs interference fit because it is mostly shaft rotation. IKO bearing with cylindrical hole is pressed in by press or hot assembly method. In the case of taper hole, it can be directly installed on the taper shaft or installed with sleeve.Installation method and precautions of IKO bearing
  • When it is installed into the shell, there are usually many clearance fits, and the outer ring has interference. It is usually pressed in with a press, or there is a cold shrinkage fit method for installation after cooling. When dry ice is used as coolant and cold shrinkage is used for installation, the moisture in the air will condense on the surface of IKO bearing. Therefore, appropriate anti rust measures are needed.Installation method and precautions of IKO bearing
  • Although the quality of IKO bearing is relatively good, the rolling bearing is a precision component, and its use must be carried out carefully accordingly. No matter how high performance IKO bearing is used, if it is not used properly, it will not get the expected high performance According to the fatigue life theory of rolling bearing, a SKF Bearing with excellent design, material, excellent manufacture and correct device, as long as the load it receives is easy enough (not greater than a certain durability limit load value corresponding to the bearing), the data of this bearing will never be damaged by fatigue. Installation method and precautions of IKO bearing
  • However, the infinity of bearings can only be “completed” under the conditions of the laboratory, and such conditions are difficult and too expensive for bearings used on site under certain working conditions.Installation method and precautions of IKO bearing
  • When SKF Bearing is used on site, its working load is often greater than its corresponding fatigue durability limit load. After working for a certain period of time, it will be unable to continue to use because its own data reaches the fatigue limit sooner or later. Installation method and precautions of IKO bearing

 Inspection of hole coaxiality error

  • Even if the working load of some SKF bearings is lower than their corresponding durability limit load, they will be worn out due to the bearing pollution problem that is difficult to eradicate. In short, the bearings in field operation can not fully meet the conditions of the above laboratories, and the slight lack of any of these conditions will shorten the service life of the bearings, which leads to the problem of bearing life.Installation method and precautions of IKO bearing
  • Generally speaking, the service life of rolling bearing refers to the professional service period that the rolling bearing can continuously meet the working performance and working accuracy actively requested under the practical service conditions (including working conditions, environmental conditions, maintenance and home care conditions, etc.).Installation method and precautions of IKO bearing
  • Bearing roundness error inspection roundness error is measured in the deviation of the radius of the hole, and a certain measuring instrument shall be used.
  • At present, general measuring tools are widely used in practical production, such as inner diameter dial gauge. At this time, the roundness error of bearing should be evaluated by half of the large difference in diameter. This method is called two-point method. It has low measurement accuracy, but it has certain application value.Installation method and precautions of IKO bearing
  •   The inspection method of the cylindricity error of the bearing cylindricity error inspection hole is the same as that of the IKO bearing cylindricity error of the outer cylindrical surface. In practice, it is difficult to accurately check the cylindricity error of the hole in production, so it can often be controlled by the parallelism of the outer bus of the inner hole, that is, the drum, saddle and cone errors of the cylindrical surface can be controlled. These errors can be checked and controlled with ordinary general measuring tools, which is convenient and applicable.Installation method and precautions of IKO bearing
  • The coaxiality of the hole refers to the level that the axis of the measured cylindrical surface is not coaxial with the reference axis., A comprehensive gauge can be used to check the coaxiality error of the two holes. If the gauge can pass through the reference hole and the measured hole, the coaxiality will pass, but it will fail. At this time, the step diameter of the comprehensive gauge shall be within the size of the two holes; It is required that the shape error of the two holes is small.Installation method and precautions of IKO bearing
  • How to measure the dimensions of bearings and bearing holes

Measurement of bearing hole

  • For the measurement of the bearing hole, the inner diameter gauge can be used to check the reference size on the outer diameter micrometer, and the roundness and cylindricity of the bearing hole also need to be measured. Burning out the bearing often reduces the diameter of the bearing hole at the opening and the roundness is out of tolerance, which is very bad for the normal task of the bearing. The connecting rod bearing cap will shift and make the roundness of the bearing hole out of tolerance. The roundness error of IKO bearing hole should be controlled within the size service, while the cylindricity should be strictly controlled.Installation method and precautions of IKO bearing
  • Bearing thickness: fix the outside micrometer and change the measuring head from plane to spherical surface, which can be used to measure the bearing thickness. The thickness of the bearing should be controlled within the limit of 0.005 ~ 0.010 mm, otherwise the inner diameter of the bearing will be out of tolerance. The bearing has slight thinning near the opening, which should be paid attention to during measurement.Installation method and precautions of IKO bearing
  • Common tightness of bearing and bearing hole: the common tightness is guaranteed by the free spring opening and residual surface height of the bearing. Under the method of measuring the height of the remaining surface: assemble the bearing according to the rules, tighten the bolts of the bearing cover to the regular torque, loosen one of the bolts, and measure the clearance at the interface of the bearing cover with a feeler gauge, which shall be within the limit of 0.05 ~ 0.15mm.Installation method and precautions of IKO bearing
  • Bearing inner diameter: before measurement, install the bearing according to the rules and tighten the bolts of the bearing cover according to the regular torque. Measure with the inner diameter gauge after correcting the reference size on the outer diameter micrometer. Avoid the thinning area during measurement. The difference between the inner diameter of the bearing and the outer diameter of the corresponding journal is the common clearance.Installation method and precautions of IKO bearing
  • Coaxiality of the inner hole of the main bearing: the coaxiality error of the inner hole of the main bearing is mainly formed by the coaxiality error of the bearing hole, and the cause of the coaxiality error of the bearing hole is the deformation of the cylinder block. When the radial circular runout of the main journal is within the regular public service, reflect on the eating and closing marks of the main journal and the bearing.Installation method and precautions of IKO bearing
  •  If the eating and closing marks of each main IKO bearing are in a clear position and clarify that the coaxiality error is large, it can be handled by scraping, boring the bearing or changing the cylinder block, otherwise it is difficult to ensure the normal task of the generator.Installation method and precautions of IKO bearing
  • For the use of bearings, noise is very common. Even the low-noise bearings in Koyo imported bearings have the same situation. So why does it make noise? Today I will introduce its essence to you.

Measurement of primary dimension of IKO bearing

  • The raceway sound of Koyo imported bearing and its control method raceway sound is a smooth and continuous sound generated by the rolling body rolling on the raceway surface when Koyo imported bearing is running. It is a unique basic sound that will occur in all rolling bearings. The general bearing sound is the sound of raceway plus other sounds.
  •  The raceway sound of ball bearing is irregular, and its frequency is above 1000Hz. Its main frequency does not change with the speed, but its total sound pressure level increases with the speed. For the bearing with loud raceway sound, the sound pressure level of raceway sound decreases with the increase of viscosity; For bearings with low raceway noise, the sound pressure level changes from decrease to increase when the viscosity increases to more than 20mm2 / s.
  • The greater the rigidity of the bearing pedestal, the lower the total sound pressure level of the raceway sound. If the radial clearance is too small, the total sound pressure level and dominant frequency of raceway sound will increase sharply with the decrease of radial clearance.
  •  The methods to control the sound of raceway are: select low-noise bearings, that is, bearings with small waviness, and carefully select the service conditions. Raceway noise often affects the noise of the whole machinery. Reducing raceway noise can reduce the noise of the whole machinery.Installation method and precautions of IKO bearing
  • Impact sound of rolling element and its control method when the ball bearing or cylindrical roller bearing of larger model runs at low speed under pure radial load, due to the small centrifugal force of the rolling element, the rolling element in the non load area will impact the cage or raceway and make noise. But as the speed increases, the sound will disappear. The control methods of impact sound of rolling elements are: appropriately reduce the radial clearance, and use the bearing of cage with reasonable structure and flexible material.Installation method and precautions of IKO bearing
  • The rolling sound of imported Koyo bearings and its control method rolling sound is the harsh metal friction sound that can occur in cylindrical roller bearings on all occasions. Most of it occurs in larger types of grease lubricated bearings, which is more likely to occur in greases with degraded base oil performance and hardly occurs in oil lubrication. In addition, it is easy to occur in winter. When bearing pure radial load, it is easy to occur in the case of large radial clearance, and it is easy to occur in a specific speed range with different models and sizes, both continuously and intermittently. 
  • Special processing methods for the outer ring raceway can prevent the occurrence of rolling sound. If necessary, this kind of bearing can be selected, or the radial clearance of the bearing can be appropriately reduced, the lubricating grease with excellent performance can be used and the rigidity of the parts matched with the bearing can be improved. In order to ensure the working condition of NTN bearing, it is necessary to avoid damage as much as possible. What should we do?
  • Generally, 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 called the quality service limit of 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.

Cold plastic deformation layer

  • As for the damage state of NTN bearing, for example, the clamping damage of the ring retaining edge of roller bearing can be considered as the reason. These reasons can also coincide with insufficient lubricant, unsuitable, defects of oil supply and drainage structure, intrusion of foreign matters, bearing installation error and excessive deflection of shaft.
  • 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, the situation before and after the accident, and combined with the damage state of the bearing and several causes, you can prevent the recurrence of similar accidents. The use factors of Koyo bearings mainly refer to whether the installation, adjustment, use and maintenance, maintenance and repair meet the technical requirements.
  • According to the technical requirements of Koyo bearing installation, use, maintenance and repair, monitor and inspect the load, speed, working temperature, vibration, noise and lubrication conditions of the running bearing, find out the causes immediately and adjust them to make them return to normal. The installation condition is one of the primary factors in the use factors.
  • The improper installation of the bearing often leads to the change of the stress state between the parts of the whole bearing. The bearing operates in an abnormal state and ends its service life early. The internal factors mainly refer to the three factors that determine the quality of Koyo bearing, such as structural design, manufacturing process and material quality. Precautions: use accurately machined NTN bearing pedestal and shoulder
  • Therefore, it is necessary to continuously monitor the bearing temperature. NTN bearing is used to measure the bearing itself or other important parts. If the operating conditions remain unchanged, any temperature change can indicate that a fault has occurred. The periodic measurement of bearing temperature can be aided by thermometer, such as digital thermometer, which can accurately measure the bearing temperature and display it in ℃ or Fahrenheit.
  • Generally, the temperature of the bearing can be inferred from the temperature outside the bearing chamber. If the oil hole can be used to directly measure the temperature of the outer ring of the bearing, NTN bearing is more suitable. Usually, the temperature of the bearing starts to rise slowly with the operation of the bearing, 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 lubrication and installation parts are appropriate, 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. Proper material selection is still a factor that must be considered in bearing failure analysis.
  • The main task of NSK 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 the bearing and avoid sudden early failure of the bearing. The installation condition is one of the primary factors in the use factors. 
  • Grinding force
  • 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 stress in the surface 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.
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