1, channel unilateral limit position peeling
The extreme position spalling of gully is mainly manifested in the serious spalling zone at the junction of gully and retaining edge. The reason is that the bearing is not installed in place or suddenly axial overload in the process of operation.
The solution is to ensure that the bearing is installed in place or change the free side bearing outer ring fit to clearance fit, in order to compensate the bearing when the bearing is overloaded.
If the installation is not in place, it can improve the film thickness of the lubricant (improve the viscosity of the lubricating oil), or reduce the load of the bearing and reduce the direct contact of the bearing.
2, the channel in the circumferential direction symmetrical peeling
The symmetrical position is shown as the inner ring around the strip peeling, the outer ring circumferential symmetric position peeling (that is, the direction of the ellipse short axis), the main reason is that the ellipse of the shell hole is too large or the two half separation shell hole structure, especially obvious in the motorcycle camshaft bearing.
When the bearing is pressed into the elliptical hole or the two halves of the separation shell are fixed, the bearing ring is elliptical, and the clearance in the short axis direction is significantly reduced or even negative.
Under the action of load, the inner ring rotates to produce circumferential spalling traces, while the outer ring only produces spalling traces in the symmetrical position of the short axis direction. This is the main cause of early bearing failure. The inspection of the faulty parts of the bearing shows that the roundness of the outer diameter of the bearing has changed from 0.8um controlled by the original process to 27um. This value is much larger than the radial clearance value.
Therefore, it is certain that the bearing works under severe deformation and negative clearance, and the working face is easy to form abnormal sharp wear and spalling.
The solution is to improve the machining accuracy of shell hole or avoid using the separation structure of shell hole.
3, raceway tilt peeling
The working surface of the bearing shows an inclined spalling zone, indicating that the bearing works in an inclined state. When the tilt Angle reaches or exceeds the critical state, it is easy to form abnormal sharp wear and spalling in the early stage. The main reason is bad installation, shaft deflection. Low precision of journal and shell holes.
Measures are taken to ensure the quality of bearing installation and improve shaft shoulder. Hole shoulder axial runout precision, or improve lubricating oil viscosity, get thicker lubrication film.
4. The ferrule is broken
Ring breakage is rare and usually caused by sudden overload. The reasons are complex, such as bearing raw material defects (bubble shrinkage), forging defects (overheating), heat treatment defects (overheating), processing defects (local burns or surface micro-cracks), host defects (poor installation, poor lubrication, instantaneous overload), etc. The ferrule may break due to overloading, shock load or violent vibration.
The countermeasures are to avoid overload and impact load, choose appropriate interference, improve installation accuracy, improve service conditions and strengthen quality control in bearing manufacturing process.
5, cage fracture
Cage fracture is an occasional abnormal fault mode. There are five main reasons:
A. Maintain abnormal load on the shelf
If the installation is not in place, tilt, too much interference easily lead to clearance reduction, increased friction heating, surface softening, abnormal peeling early.
As spalling expands, spalling foreign matter enters cage pockets, causing cage operation clogging, generating additional load and exacerbating cage wear. Such a worsening circulation effect could lead to cage rupture.
B. Poor lubrication
Mainly refers to the bearing is in the state of lean oil, easy to form adhesive wear, deterioration of the working surface state, adhesive wear tear easily into cage, cage to produce abnormal load, may lead to cage fracture.
C. Foreign body invasion is the common mode of cage fracture failure.
Due to the invasion of foreign hard foreign matter, cage wear and abnormal additional load, may also lead to cage fracture.
D. Creep is also one of the causes of cage fracture
Creep refers to the sliding phenomenon of the ring. In the case of insufficient interference of the mating surface, due to sliding, the load point moves to the surrounding direction, resulting in the relative axis of the ring or the shell deviating from the surrounding direction.
Once creep occurs, the mating surface will wear significantly, and the worn powder may enter the bearing, forming abnormal wear - raceway spalling - retaining frame wear and additional load, and may even lead to retaining frame fracture.
E. Defect of cage material
(e.g., cracks, large heterometallic inclusions, shrinkage holes, bubbles) and riveting defects (missing nails, padding nails, or gaps between the joints of the two halves of the cage, serious riveting) may cause the cage to break.
Strict control in the manufacturing process
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