Although a simple truck bearing seal cover is removed, it will not cause serious safety hazards such as vehicle shaft cutting or derailment, but due to the bearing seal cover falling out, the hot shaft rises quickly and the temperature is high. Infrared equipment predicts strong heat and more heat. , Most of them stopped on the way, which seriously affected the transportation order. The following China Bearing Network (abbreviation: Huazhou Network), based on the understanding of truck bearings, shares the reasons for the falling off of the truck bearing seal cover and the corresponding prevention and control measures.
Reasons why the truck bearing seal cover came out during operation
In most cases, the sealing cover is not caused by one cause, but a combination of multiple factors, some of which pop up instantly, and some are moved out little by little. Let's analyze the main reasons that cause the sealing cover to fall out:
1) The groove and chamfer of the outer ring of the bearing are not standard
According to the analysis of the reasons for the sealing cover to come out in recent years, the non-standard processing of the groove and chamfer of the outer ring of the bearing is the main reason for the sealing cover to come out of the bearing. The bearing seal cover and the outer ring are assembled to form a non-moving integrated structure. The circumferential movement between the seal cover and the outer ring is due to the interference fit between the seal cover and the outer ring teeth, and the axial non-movement is the interference fit and As a result of the joint action of the boss of the sealing cover entering the groove of the outer ring of the bearing to prevent the sealing cover from moving, whether the groove of the outer ring of the bearing is standard or not plays a decisive role in preventing the sealing cover from falling out. The groove depth and width are not standard or the grooves have ribs not only fail to prevent the sealing cover from moving out, but also destroy the interference fit between the outer ring teeth and the sealing cover, causing the sealing cover to fall out.
2) The thickness of the sealing cover is insufficient, the strength is small, or the processing of the mouth and the boss is not standard
According to the requirements of the drawings, the sealing cover is stamped and formed with a 2.5mm thick steel plate, and the mouth and boss are machined to ensure that the size of the mating surface of the mouth and the boss meets the standard. In order to process the height of the boss 0.26±0.06mm, the thickness of the mating surface of the sealing cover is generally between 2.1~2.2mm, and the thinnest is only about 2.0mm. The seal cover is deformed due to insufficient strength during the assembly or vehicle operation, or the seal cover is deformed due to the clamping and unreasonable processing volume during the processing, which makes the roundness or the size of the boss not standard, causing the seal cover to fall out during operation.
3) The optional interference between the seal cover and the outer ring of the bearing does not meet the standard
Reasonable selection of the matching interference between the seal cover and the outer ring of the bearing can not only prevent the mutual circumferential rotation, but also play an important role in preventing the axial escape of the seal cover. Insufficient interference, the seal cover is prone to loose or fall out due to centrifugal force and rotational torque during vehicle operation. Excessive interference is easy to damage or even cut off the boss during the assembly process of the sealing cover, and will cause the sealing cover to produce great elastic deformation and stress, and it is easy to come out instantaneously when subjected to vibration or impact.
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4) During the assembly process of the seal cover, the mold and the bearing are not concentric, and the boss of the seal cover is damaged and cut off
The installation position of the mold of the seal cover assembly machine is inaccurate or the mold wear is out of concentricity with the bearing. When the seal cover is assembled, the seal cover is forced into the outer ring of the bearing by the pressing force, which will damage the seal cover boss or even partially cut it off. During the operation of the vehicle, the sealing cover first comes out of the damaged part of the boss.
5) The internal failure of the bearing or the poor fit between the raceways, the large temperature difference between the inside and outside of the bearing
Internal faults of the bearing, such as raceway surface peeling, rolling, poor fit between the inner and outer ring raceways and rollers, impurities in the grease, non-compliant grease injection, excessive or small bearing clearance, etc., make the bearing Heat is generated during operation, the internal temperature rises, and the pressure increases. Especially in winter, the temperature difference between the inside and outside of the bearing is large, which increases the force of the sealing cover to escape outward. and
In addition, the internal heat of the bearing is first generated or conducted to the outer ring, and then to the sealing cover through the outer ring. The thermal expansion of the outer ring reduces the interference with the sealing cover and increases the possibility of the sealing cover coming out.
6) Improper selection of the interference between the bearing and the journal when the bearing is press-fitted
When the interference between the bearing and the journal is too large, the bearing clearance will be reduced, the rotation resistance of the vehicle will increase when the vehicle passes the curve, and the bearing temperature will increase. The interference between the bearing and the journal is too small, especially if the journal has an inverted taper, the interference between the inner ring of the bearing and the journal is too small, causing fretting and abrasion between the journal and the inner ring of the bearing, which also causes the bearing The temperature rises. If the fretting abrasion gradually increases, it may cause the bearing to rotate. If it is not found in time, it will be more dangerous to cut the shaft.
7) Wheel tread scratches, poor vehicle running quality
Wheel tread scratches, peeling, and other faults will cause the vehicle to vibrate during operation, impact the bearing, deform the bearing outer ring teeth and the sealing cover, and cause the sealing cover to fall out in severe cases. Since the outer side of the bearing has the largest amount of deformation when it is subjected to vibration and impact, most of the sealing cover that comes out is the sealing cover on the outer side of the bearing.
In addition, the eccentric load of the vehicle, the centrifugal force when passing the curve, the impact on the bearing when the bogie is completed, and the bump of the bearing during transportation may all cause the sealing cover to fall out.