High quality bearings can be used for a long time under correct use. If damage occurs prematurely, it may be caused by wrong selection, improper use or poor lubrication.
Therefore, in the installation of bearings, we need to record the type of machine, installation location, use conditions and surrounding coordination. Through research and summary of bearing damage types, the use of the environment when problems occur, in order to avoid the recurrence of similar situations.
Bearing damage modes are classified according to the following pictures. The main features shown in the pictures can be used to judge the bearing damage modes.
Crack defect, some of the notches have cracks.
Reasons: the impact load of the main engine is too large, the interference between the spindle and the bearing is too large; there are also cracks caused by larger peeling friction; poor installation accuracy; improper use (using copper hammer, clamping large foreign body) and friction cracks.
Solutions: The service conditions should be checked, the appropriate interference and material should be set, the installation and use methods should be improved, and the lubricants should be checked to prevent friction cracks.
Metal stripping on raceway surface
Operating surface peeling. After peeling, it was obviously concave and convex.
Reasons: The rolling element of bearing and the raceway surface of inner and outer rings are subjected to periodic fluctuating loads, resulting in periodically varying contact stress. When the number of stress cycles reaches a certain value, fatigue peeling occurs on the working face of rolling body or inner and outer raceway.
If the load of the bearing is too large, the fatigue will be aggravated. In addition, the incorrect installation of bearings and the bending of axles will also cause raceway stripping.
Solutions: We should re-study the use conditions and choose bearings and clearances, and check the processing accuracy, installation methods, lubricants and lubrication methods of axles and bearing boxes.
Bearings become hot and discolored, and burn can not rotate.
Reasons: Generally, the lubrication is insufficient, the quality of lubricating oil does not meet the requirements or deterioration, and the assembly of bearings is too tight. In addition, the clearance is too small and the load is too large (pre-pressure is too large), the roller is skewed.
Solutions: Choose the appropriate clearance (or increase the clearance), check the type of lubricant, ensure the injection volume, check the use conditions, in order to prevent positioning errors, improve the assembly method of bearings.
Rivet loosening or fracture, rolling body broken.
Reasons: Torque load is too large, lubrication is insufficient, rotational speed changes frequently, vibration is large, bearing is installed in inclined state, foreign body is stuck in.
Solutions: To find out whether the use conditions and lubrication conditions are appropriate, pay attention to the use of bearings, study whether the selection of cages is appropriate and whether the rigidity of the bearing box is load requirements.
The inner or outer surface slips, causing the mirror or discoloration, and sometimes gets stuck.
Reasons: insufficient interference at the mating point, insufficient sleeve fastening, abnormal temperature rise, excessive load of the main engine, etc.
Solutions: To re-examine whether the interference is appropriate, to check the conditions of use, to check the accuracy of the shaft and bearing box.
Rust corrodes the surface partially or totally, and the rolling body becomes strip-like rust.
Reasons: poor storage, improper packaging, inadequate rust inhibitors, water and acid solvents intrusion, direct use of hand bearings. Invasion of water, corrosive substances (paint, gas, etc.). The lubricant is not suitable. Water droplets are attached to the condensation of water vapor. Stop running at high temperature and humidity. Poor rust prevention during transportation.
Solutions: to prevent rust in storage, regularly and irregularly re-oiled packaging, strengthen sealing performance, regularly check lubricating oil, timely replacement of unqualified or deteriorated oil, correct use of bearings.
Damage status: When biting small metal powder, foreign body, etc., the concave formed on the raceway surface or rotating surface. Because of the impact during installation, concave surface (Brinell hardness indentation) is formed on the interval between the rollers.
Cause: Foreign bodies such as metal powder bite in. The impact load during assembly or transportation is too large.
Solution: impact sleeve. Improve the sealing device. Filter lubricants. Improve assembly and use methods.
Damage state: The so-called wear is caused by friction, such as raceway surface or rolling surface, roller end surface, shaft ring surface and cage concave surface.
Reasons: foreign body intrusion; development caused by rust and corrosion; poor lubrication; slippage caused by irregular movement of rolling element.
Solutions: improve the sealing device; clean the bearing box; fully filter the lubricant; check the lubricant and lubrication methods.
Pseudo-Brinell indentation of bearings
Damage status: During the period of micro-vibration, the contact part between rolling body and raceway wheel develops wear due to vibration and shaking, and produces the impression like Brinell indentation.
Cause: In the course of transportation, the vibration and swing of the bearing when it stops running. Oscillating motion with small amplitude. Bad lubrication.
Solution: Shaft and bearing box should be fixed during transportation. The inner and outer rings should be packed separately during transportation. The vibration is reduced by preloading. Use appropriate lubricants.
Damage status: The material is transferred from one working surface to another, accompanied by friction heating, sometimes accompanied by surface tempering and re-quenching. This process will produce local stress concentration in the contact area and may lead to cracking or spalling.
Reasons: Because of the uneven force on the working face caused by the micro-protrusion or foreign body of the working face, when the lubrication deteriorates seriously, the local friction heating will easily cause the local deformation of the working face and the phenomenon of friction micro-welding. In serious cases, the metal of the working face may melt locally, and the local friction welding point will be torn from the body by the force on the base surface. The plastic deformation is increased.