Rolling bearings are important parts in rotating machinery. Statistics show that in rotating machinery using rolling bearings, about 30% of mechanical failures are caused by rolling bearings. With the use of condition detection and fault diagnosis technology, the accident rate can be reduced by 75%, and maintenance costs can be reduced by 25% to 50%.
First, the form of failure of rolling bearings
(One) Fatigue spalling
The inner and outer raceways and rolling elements of the rolling bearing alternately enter and exit the load bearing area. Due to the long-term bearing of the alternating load, these components first generate fatigue cracks from the maximum alternating shear stress below the contact surface, and then extend to the contact surface to produce on the surface. Point spalling gradually develops into large scale spalling, which is called fatigue spalling.
Due to the relative motion of the raceway and rolling elements and the surface caused by dust and foreign bodies, poor lubrication will aggravate the wear. As a result, the bearing clearance is increased, the surface roughness is increased, the bearing accuracy is reduced, and the machine motion accuracy is also reduced. It appears as an increase in vibration level and noise.
Because the micro-convex or hard particles on the contact surfaces of the inner and outer raceways of the bearing and the rolling elements make the contact surface uneven, under poor lubrication and high-speed and heavy-load conditions, the contact surface is locally deformed due to heat generated by local friction and Friction welding. In severe cases, the surface metal may locally melt, and the force on the contact surface will tear the local friction welding point from the substrate.
When the bearing is subjected to excessive load and vibration, the defect position of the inner and outer rings is gradually expanded and broken under the repeated impact of the rolling body.
Direct intrusion of moisture or acids and alkaline substances can cause bearing corrosion. When a shaft current passes through the bearing, electric sparks are generated at the contact points between the raceways and the rolling elements, and electric erosion occurs, and a rubbing-like unevenness is formed on the surface.