1. The bearing contact fatigue failure
Contact fatigue failure refers to the bearing working surface under the role of alternating stress and failure. Contact fatigue spalling occurred in bearing working surface, often accompanied by fatigue crack, first of all, from the maximum cyclic shear stress under contact surface, and then extended to form a different flake shape, such as dot to pitting corrosion or pitting spalling, peel into small sheet according to the shallow flaking. Due to spalling surface expands gradually, and often to deep extension, forming deep spalling. Deep spalling is contact fatigue failure of fatigue source.
2. Bearing wear failure
Refers to the relative sliding friction between the surface abrasion failure lead to constant wear and tear of the working surface of the metal and the failure. Continuous wear will cause NTN Bearing Thickness http://www.fagbearings-hk.com/NTN-Bearings.html parts damaged gradually, and ultimately result in the loss bearing dimensional accuracy and other related issues. Wear may affect the shape change, the increase of fit clearance and working surface morphology change, may affect the lubricant or make its pollution to a certain degree of lubrication function is lost, so that loss of bearing rotating accuracy and will not operate properly. Wear failure is one of the common failure modes of all kinds of bearings, according to the wear and tear is usually divided into one of the most common form of abrasive wear and adhesive wear.
Work of abrasive wear refers to the bearing surface between into hard foreign matter or foreign solid particles or abrasive dust on the surface of the metal caused by the relative movement and the contact surface of wear, often cause furrow of abrasion in bearings working surface. Hard particles or other foreign body may come from inside the host, or from the host system adjacent parts sent by lubricating medium bearing inside. Adhesive wear refers to the because of the friction surface microscopic bumps or foreign bodies make the friction surface is uneven, serious deterioration, the condition of lubrication for local friction heat production, easy to cause local deformation and friction surface friction welded phenomenon, serious when the surface of the metal may be the partial melting, contact surface forces from the local friction welding points on the matrix will be torn and increase the plastic deformation. This kind of adhesive, tearing, adhesive cycle constitutes the adhesive wear and tear, in general, mild adhesive wear is called a scratch, serious adhesive wear called occlusion.
3. The bearing failure
Bearing failure of the main reason is that defects and overload two factors. When the loads more than material strength limit fracture caused by parts called overload fracture. Overload reason mainly is the main engine failure or improper installation. Bearing parts of micro crack, shrinkage cavity, bubbles and large foreign impurities, overheating organizations and local burns and other defects during the impact overload or violent vibration will cause fracture in defect, known as defect fracture. It should be pointed out that the bearing in the process of manufacturing, for raw materials into the factory reinspection, forging and heat treatment quality control, process control through instrument analysis of the existence of the above defects and correct still must strengthen control in the future. But in general, usually bearing fracture failure of most for overload failure.
The cause of the high bearing temperature are: lubricating oil quality does not conform to the requirements or metamorphism, lubricating oil viscosity is too high; The assemble tight (inadequate clearance); Bearing assembly too tight; Bearing race in internal rotation shaft or housing; Too much load; Bearing cage or rolling body fracture, etc.
1), shaft and hole of the roundness, and retaining shoulder perpendicularity to according to the corresponding precision of bearing requirements.
2), as well as the precise rotary ring with the amount of interference, also to accurate calculation of the fixed ring with right quantity. The rotating ring burning interference quantity within may also should be made smaller. As long as to ensure that work under the temperature of thermal expansion effect, and under the maximum speed of centrifugal force effect, not cause peristalsis or sliding on the surface of the tight fit. Fixed ring according to the size of the working load and bearing size, choose the smallest clearance fit or interference fit, too loose or too tight is unfavorable to keeping the original precise shape.
3), bearing such as under the condition of high speed running, and working temperature is higher, should pay special attention to the matching of the rotating ring is too loose, to prevent the eccentric vibration, and the matching of the fixed ring is a gap, in order to prevent the ferrule deformation and vibration under load.
The functioning of the rolling bearing in the work to allow a slight noise, if you have any abnormal noise or excessive noise or sound, suggests that the bearing failure.
Cause noise of rolling bearings is more complex, one is the bearing inner and outer surface wear. Due to this kind of wear and tear, damage the bearing and shell, bearing and shaft cooperate relationship, lead to axis deviation from the correct position, when axis at high speed movement produces sound. When the bearing fatigue, its surface metal flake, also can produce sound make bearing radial clearance increases.
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