Analysis of common faults and causes

Rolling mill bearings may be damaged due to various reasons during operation, such as improper assembly, poor lubrication, moisture and foreign body intrusion, corrosion and overload, etc. may cause premature bearing damage.Even under normal installation, lubrication, use and maintenance, after a period of operation, the bearing will experience fatigue, peeling and wear and will not work properly. In short, the causes of failure of rolling mill bearings are very complex, and the common faults and causes are analyzed as follows.

1. Fatigue flaking

The inner and outer racetracks of rolling bearings and the surface of rolling elements are both under load and relatively rolling. Due to the action of alternating loads, cracks first form at a certain depth under the surface (at the maximum shear stress), and then extend to the contact surface to cause the surface layer to peel off pits, and finally develop into large flakes. This phenomenon is fatigue flaking.Fatigue flaking will cause increased shock loads, vibration and noise during operation.Under normal circumstances, fatigue flaking is often the main cause of rolling bearing failure.

2. Wear and tear

Due to the invasion of dust and foreign objects, the relative movement of the raceway and rolling elements will cause surface wear, and poor lubrication will also exacerbate the wear. As a result of the wear, the bearing clearance increases, the surface roughness increases, and the bearing operation accuracy is reduced. At the same time, vibration and noise also increase.Therefore, to a certain extent, the amount of wear limits the life of the bearing.

3. Plastic deformation

When the shaft is subjected to excessive impact load or static load, or additional load due to thermal deformation, or when a foreign body with high hardness invades, dents or scratches will form on the surface of the raceway.This will cause the bearing to produce severe vibration and noise during operation, and once there is an indentation, the impact load caused by the indentation will further cause the nearby surface to peel off.

Daily maintenance

1. Inspection of bearings during operation

In accordance with maintenance procedures, the bearings are regularly listened to, observed and measured.Listening is to use one end of the listening rod to face the axial end cap of the bearing and the radial shell of the bearing seat, and the other end is attached to the ear to listen to whether the bearing has impact and mechanical friction during operation.Observation is to observe the operating environment, installation location, vibration offset, lubrication conditions, etc., and whether there are undesirable working conditions.Measurement is the use of thermometers and vibrators to conduct regular inspections of the bearing seat.Using these methods, the bearings are checked regularly to determine whether the bearings are in normal condition.

2. Inspection of bearings in a stationary state

Check the fastening of the relevant parts to confirm whether the parts are in the correct position, whether there is abnormal loosening, etc. In addition, the bearing lubrication is tested to detect whether there are foreign objects in the lubricating oil.When the diameter of the foreign body is less than the minimum working gap of the bearing, the foreign body can agitate with the lubricating oil through the gap.Friction occurs on the working surface of the rolling element. When the diameter of the foreign body is greater than the working gap of the bearing, the foreign body is crushed or crushed into a thin dust that adheres to the surface of the bearing or is embedded in it.However, if the crushed foreign body debris is not embedded in the work surface and enters the lubricating oil, the bearing wear will be more severe.This causes the bearing to fatigue and peel off.Cause the temperature of the work surface to rise.The lubricating oil then loses its effect.The bearing fails, and after the foreign body is crushed or embedded in the rolling element, the oil film is quickly destroyed, causing the bearing to be damaged during operation in a dry friction state.

3. Post-disassembly inspection of bearings

When the roll is replaced, a cleaning agent can be used to clean the bearing, blow it dry with compressed air, and then inspect the roller, cage, and raceway.Dents, pitting and other phenomena appear on the rollers and racetracks, and they should be replaced according to specific circumstances. At the same time, replace the necessary bearing seals to prevent the life of the bearing from being affected by poor sealing.If the bearing is poorly sealed and the emulsion enters the bearing, it will cause water pollution to the lubricating oil or grease, resulting in a decrease in the fatigue strength of the bearing material and easy to crack. At the same time, the sealing is poor, and the iron oxide sheet during rolling enters the bearing to destroy the lubrication conditions, causing abrasive wear on the surface of the bearing components.

Conclusion: Through the analysis of common bearing failures and causes, and the formulation of scientific and reasonable maintenance procedures, the service life of bearings can be effectively improved, the incidence of accidents can be reduced, the consumption of spare parts can be reduced, and the production time can be guaranteed. It provides a strong guarantee for cost reduction and efficiency.