Criteria and treatment methods for judging fault damage of ina supercharger bearing
2022年4月7日
What should be paid attention to to to prevent IKO joinWhat should be paid attention to to to prevent IKO joint bearing failuret bearing failure
What should be paid attention to to to prevent IKO joint bearing failure
2022年4月8日

Causes of unexplained failure of Ko rotary table bearing during operation

1. Contact fatigue failure

Contact fatigue failure refers to the failure of IKO bearing working surface caused by alternating stress. Contact fatigue spalling occurs on the working surface of rotary table bearing, which is often accompanied by fatigue cracks. It first occurs from the large alternating shear stress below the contact surface, and then extends to the surface to form different spalling shapes, such as pitting or pitting spalling, and spalling into small flakes is called shallow spalling. Due to the gradual expansion of the spalling surface, it often expands to the deep layer, forming deep spalling. Deep spalling is the fatigue source of contact fatigue failure.Causes of unexplained failure of Ko rotary table bearing during operation

Causes of unexplained failure of Ko rotary table bearing during operation

2. Wear failure

  • Wear failure refers to the failure caused by the continuous wear of the metal on the working surface caused by the relative sliding friction between the surfaces. Continuous wear will gradually damage the rotary table bearing parts, and eventually lead to the loss of dimensional accuracy of IKO bearing and other related problems. Causes of unexplained failure of Ko rotary table bearing during operation
  • Wear may affect the change of shape, the increase of fit clearance and the change of working surface morphology, may affect the lubricant or make it polluted to a certain extent, resulting in the complete loss of lubrication function, so that the bearing loses the rotation accuracy and even cannot operate normally. Wear failure is one of the common failure modes of various bearings. According to the wear form, it can be divided into common abrasive wear and adhesive wear.Causes of unexplained failure of Ko rotary table bearing during operation
  • Abrasive wear refers to the wear caused by the relative movement of the contact surface due to the extrusion of foreign hard particles or hard foreign matters or wear debris on the metal surface between the working surfaces of IKO bearings, which often causes furrow like scratches on the working surfaces of imported bearings. Hard particles or foreign matters may come from the inside of the host machine or from other adjacent parts of the host system, and are sent into the bearing of the rotary table by the lubricating medium. Causes of unexplained failure of Ko rotary table bearing during operation
  • Adhesive wear refers to the uneven stress on the friction surface due to the micro bulge or foreign matter on the friction surface. When the lubrication conditions are seriously deteriorated, the local deformation and friction micro welding of the friction surface are easy to be caused due to the heat generated by local friction.Causes of unexplained failure of Ko rotary table bearing during operation
  •  In serious cases, the surface metal may be locally melted, and the force on the contact surface will tear the local friction welding point from the substrate and increase the plastic deformation. This cycle of adhesion tear adhesion constitutes adhesive wear. Generally speaking, slight adhesive wear is called scratch and severe adhesive wear is called bite.Causes of unexplained failure of Ko rotary table bearing during operation

3. Fracture failure

  • The main causes of bearing fracture failure are defect and overload. When the external load exceeds the material strength limit and causes the part to break, it is called overload fracture. The main cause of overload is the sudden failure or improper installation of the host. The defects of IKO bearing parts, such as microcracks, shrinkage cavities, bubbles, large foreign objects, overheated tissue and local burns, will also cause fracture at the defect during impact overload or violent vibration, which is called defect fracture. Causes of unexplained failure of Ko rotary table bearing during operation
  • It should be pointed out that in the manufacturing process of rotary table bearing, the presence of the above defects can be correctly analyzed by instruments in the factory re inspection of raw materials, quality control of forging and heat treatment and processing process control, and the control must be strengthened in the future. However, generally speaking, the fracture failure of IKO bearing is mostly overload failure.Causes of unexplained failure of Ko rotary table bearing during operation

4. Clearance change failure

  • During the operation of rotary table bearing, due to the influence of external or internal factors, the original matching clearance is changed, the accuracy is reduced, and even the “bite” is called clearance change failure. External factors such as excessive interference, improper installation, expansion caused by temperature rise, instantaneous overload, etc., and internal factors such as residual austenite and residual stress in an unstable state are the main reasons for the change and failure of clearance.Causes of unexplained failure of Ko rotary table bearing during operation
  • The judgment criteria vary according to mechanical properties, importance and inspection cycle. In case of the following damage, the one-way thrust ball bearing shall not be reused and must be replaced. In the process of using bearings, grease is very critical. If deteriorated grease is used, it will not only fail to play its due role, but also damage the bearing.Generation and Elimination of Noise of One-Way Thrust Ball Bearing
  • Generation and Elimination of Noise of One-Way Thrust Ball Bearing
  • Twist the lubricating oil between the thumb and index finger and grind it repeatedly. The better lubricating oil hand feels lubricity, less wear debris and no friction. If it feels a large friction feeling such as sand particles between the fingers, it indicates that there are many impurities in the lubricating oil and it can not be used again. It should be replaced with a new lubricating oil.Generation and Elimination of Noise of One-Way Thrust Ball Bearing
  • Raceway sound of one-way thrust ball bearing and its control method raceway sound is a smooth and continuous sound made by the rolling body rolling on the raceway surface when the one-way 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.Generation and Elimination of Noise of One-Way Thrust Ball Bearing
  •  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 lower the sound level of the bearing, the greater the total sound pressure of the bearing. 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. Causes of unexplained failure of Ko rotary table bearing during operation
  • 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.Generation and Elimination of Noise of One-Way Thrust Ball Bearing
  • The metallurgical quality of unidirectional thrust ball bearing material was once the main factor affecting the early failure of bearing. With the improvement of Metallurgical Technology (such as vacuum degassing of bearing steel), the quality of raw materials has been improved. The proportion of raw material quality factor in bearing failure analysis has decreased significantly, but it is still one of the main influencing factors of bearing failure. Proper material selection is still a factor that must be considered in bearing failure analysis.Generation and Elimination of Noise of One-Way Thrust Ball Bearing
  • The main task of failure analysis of one-way thrust ball bearing 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 self-aligning roller bearing and avoid sudden early failure of bearing.
  • The vibration of one-way thrust ball bearing has a significant effect on the failure of bearing. For example: peeling, indentation, corrosion, crack Wear, etc. will be reflected in the bearing vibration detection, so the vibration can be measured by using special bearing vibration measurement devices (frequency analyzer and vibration instrument, etc.), and the details of abnormal vibration can be inferred from the frequency distribution. Causes of unexplained failure of Ko rotary table bearing during operation
  • The measured values are different due to the use premise 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 and determine the judgment scale.Causes of unexplained failure of Ko rotary table bearing during operation
  • 1. Cause: the inner shell of the bearing runs. Method: replace the bearing and related worn parts
  • 2. Cause: poor lubrication method: select the specified brand of lubricating materials and clean them properly
  • 3. Cause: the belt is too tight. Method: adjust the belt to make it elastic properly.Causes of unexplained failure of Ko rotary table bearing during operation
  • 4. Cause: the main shaft is bent or the box hole is not concentric. Method: repair the main shaft or box.Causes of unexplained failure of Ko rotary table bearing during operation
  • 5. Cause: low assembly quality method: improve assembly quality
  • 6. Cause: low bearing accuracy method: select the bearing with specified accuracy grade
  • 7. Method of excessive axial force: clean and adjust the clearance of sealing ring between 0.2 ~ 0.3mm, correct the diameter of impeller balance hole and verify the static balance value.Causes of unexplained failure of Ko rotary table bearing during operation
  • 8. Bearing damage method: replace the bearing
Causes of unexplained failure of Ko rotary table bearing during operation