Failure form of GCr15 bearing steel
Bearing steel under the combined effect of complex factors, the bearing is destroyed after a considerable period of operation. There are two main forms of damage: one is contact fatigue damage. Under the action of high contact stress, after multiple stress cycles, pits are generated in the local area of the working surface, so that the noise increases and the vibration increases when the bearing works. The temperature rises and the wear increases, causing the bearings to fail to operate properly. The other is wear and tear caused by relative activities. The normal form of failure of rolling bearings is usually fatigue spalling.
Fatigue failure of bearing steel includes two processes of generation and development of fatigue cracks. The initial fatigue crack is generated at a certain depth from the surface, which is exactly the same as the depth of the maximum shear stress. For bearings of normal size, the maximum shear stress should occur somewhere between 0.35 and 0.55 mm of the contact surface, depending on the load. The metal in this area first undergoes plastic deformation under the action of maximum shear stress. If the contact stress is greater than the contact fatigue limit of the material, as the number of stress cycles increases, the plastic deformation has been continuously plastically deformed, and fatigue cracking cannot be performed here due to plastic deformation. Under normal conditions, the microcracks are at an angle of approximately 45° on the surface. Fracture spalling cracks on the contact track of the rolling bearing gradually expand under repeated stress, usually along the materialhttps://www.supplyforever.com/
Correct use of NTN one-way bearings
The correct maintenance and timely maintenance of NTN bearings is an important aspect to ensure the normal operation of road machinery. If the maintenance and maintenance of the bearing is good, it can work for several thousand to disappear or even longer; on the contrary, the service life of the bearing will be greatly reduced, and even serious accidents such as burning the tile and holding the axle will occur. Generally, the working temperature of the lubricating oil of the one-way bearing should not exceed 50 ° C. In order to ensure sufficient lubricating oil and reliable lubrication, the oil surface should be inspected in time or periodically to keep the oil surface within the specified range. To maintain some cleanliness, replace them according to the quality requirements of the oil. The specific conditions of the bearing failure should be analyzed and eliminated in time. Common faults and handling methods for bearings are as follows.
(1) The bearing is hot. If the NTN bearing lubricant is insufficient, it should be refueled and check whether the oil circuit is smooth; if the lubricating oil has impurities, the bearing should be cleaned, replaced with new oil, and the filter should be cleaned; if the assembly is poor, the journal and the bearing are skewed and eccentric, Add a spacer to the bottom of the housing; if the bearing clearance is too small, re-adjust the clearance.
(2) The shaft is hot. If the oil retaining or rubber seal on the shaft is too tight, adjust the position of the back cover of the packing; if the shaft and the bearing cover have radial friction, check and adjust the radial clearance between the shaft and the bearing cover, generally 0.25~0.3mm.
(3) The amount of oil on the main friction surface is small. If the oil pipe is clogged and the oil groove is shallow, the pipeline should be cleaned and the oil groove should be deepened; if the oil temperature is low and the fluidity is poor, the lubricating oil should be replaced according to the ambient temperature; if the oil ring rotates slowly and the oil splash is bad, the oil ring should be checked for falling off. Rub the edge, the oil level is too high to drain the oil to the standard height; if the adjustment gasket blocks the lubricant, check the adjustment gasket position.
(4) Oil leakage. If the amount of oil is too much, the oil supply should be adjusted to maintain the standard height of the oil surface; if the sealing device fails, the gland should be pressed tightly, the felt ring should be thickened or the sealing material should be replaced; if the NTN bearing seat has holes and oil seepage, the bearing should be replaced. Block the pores with lead filling method.
(5) Axial jump. If the bearing clearance is too large, remove the gasket and adjust; if the rotating body (gear, tape wheel, etc.) is not well balanced, check and adjust the dynamic balance; if the bearing is not stable, tighten the bearing bolt; The shaft is installed with a large offset. The gasket should be placed on the ground of the bearing seat to adjust the installation accuracy of the coupling.
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