(1) Appropriate tightening: The inner and outer rings of the rolling bearing are subject to different load conditions due to different working conditions. Therefore, it is necessary to first understand the movement and stress of the inner and outer rings of the bearing. Is the inner ring rotating? Or is the outer ring turning? Because the rotating ferrule acts under the external force in the fixed direction, the load is the "circulating load" of the force exerted by each point on the entire ferrule, so the raceway is worn comprehensively and evenly. In order to prevent the ferrule and the assembled parts from sliding against each other and causing wear, the fit is generally selected tightly, and the first, second, third and fourth transition fits are often used. The fixed ferrule, under the external force in the fixed direction, is subjected to the "local load" of the fixed part. The raceway is only partially affected by the force and partially worn. In order to improve the stress conditions, the fit between the fixed ferrule and the assembled part should be loosened, often using one, two, three dynamic fits or a fourth transition fit. By adopting such a loose fitting, the fixed ferrule can be intermittently and slowly rotated under the action of impact or vibration, so that the rolling portions are subjected to the force in turn and uniformly weared, which is beneficial to prolonging the service life of the bearing. The type of fit between the fixed ferrule and the part can be selected according to the following principles:
1 The variable load that is easy to generate shock and vibration is tighter than the fixed load.
2 heavy load is tighter than light load.
3 requires high rotation precision and tighter than the rotation precision.
4 matching parts (such as bearing housing holes) have high shape accuracy and tighter than the shape accuracy.
When installing the bearing, according to the above principles and the original design requirements of the machine, the inner ring and the part should be tightly fitted, and the first measuring tool or bearing should be tested. Any bearing that is too tight to be scraped, too loose to be repaired, trimmed or exchanged.
Whether the fixed ferrule rotates slowly can be determined according to the matching conditions, such as whether the surface of the bearing housing hole is polished or the position is changed according to whether the ferrule on the ferrule and the red lacquer mark change position during operation.
(2) Guarantee the necessary working clearance: In order to ensure the normal operation of the bearing, consider the expansion after the bearing runs, and there should be a certain gap between the inner and outer rings of the bearing and the rolling elements, called “play”. The clearance of the bearing is divided into radial clearance and axial clearance, and the radial clearance is a special part of the bearing installation.
Radial clearance can be divided into three types:
1 Original clearance: the clearance in the free state before the bearing is installed.
2 Coordination clearance: After the bearing is mounted on the machine parts, the inner and outer rings are affected by the interference fit, and the clearance after the expansion and contraction of the diameter is changed.
3 Working clearance: When the bearing is in working condition, due to running heat and load, the clearance is reserved for deformation.
Usually the working clearance is larger than the matching clearance, and the matching clearance is smaller than the original clearance.
When installing the bearing, it is necessary to prevent the inner ring from expanding too much, and the outer ring is compressed too small, so that the rolling element is stuck and cannot be rolled, especially when installing the tapered hole bearing with the adapter sleeve, pay more attention to the lock. The tightness of the tightening nut.
In conjunction with the inspection method of the clearance, the most commonly used is the "swing method" (for self-adjusting bearings). When inspecting, try to deflect the outer ring. If the deflection is free, it indicates that there is play; you can also push the outer ring with your hand to check whether the rotation is light. The bridging of the bearing housing before and after the bolt is tightened should not be affected.
The radial clearance of the bearing has a certain relationship with the axial clearance. Since the radial clearance is small, it is generally 0.02~0.04mm, and the axial clearance is about 12~20 times of the radial clearance. Therefore, the radial play can be indirectly checked by hand sensing the axial play. To directly measure the value of the clearance, the head of the shaft can be used to abut the surface or the head end of the shaft to raise or pull the shaft head, and the axial or radial clearance can be measured separately.
(3) Add an appropriate amount of grease: in addition to the lubricating effect, the grease also has a seal and dustproof effect. The grease added to the bearing must be in an appropriate amount. If the grease is added too little, it will shorten the fueling cycle or wear the bearing. Because the grease oil resistance is large, when the bearing rotates at high speed, it often causes heat. Therefore, the grease in the bearing and the housing cavity should not be too full. Generally, when the bearing speed is higher than 1500 rpm, only 1/3~ 1/2 cavity, generally less than 1500 rpm can be added to 1/2~2/3 cavity.
(4) Controlling axial travel: Most rolling bearings are not used individually, but often two, three ... together support a rotating part. When installing the bearing, it is necessary to find out which bearing has axial travel. Because the parts of the machine generate a temperature difference after heating, some parts are thermally expanded and extended, so the bearing mounting method on the rotating parts is different. Generally, the bearing on the transmission side is not movable in order to ensure that the axial direction of the transmission gear, pulley, sprocket, etc. is accurately unchanged. Therefore, a thrust ring should be installed in the bearing housing to limit the axial movement of the bearing. Other bearings on the coaxial should allow for swimming. When installing, the bearing should be centered in the bearing housing, leaving the swimming gap on both sides, and the matching of the fixing ring and the part should be loose, otherwise the inner and outer rings will be staggered, and the rolling elements will be stuck or worn.
(5) Correct the coaxiality of the inner and outer rings: the inner and outer rings of the rolling bearing should not be skewed to each other, so as to prevent the balls from running out of the normal raceway, so that the balls are only partially stressed or accidentally loaded, causing premature wear of the bearings. . The inner and outer rings of ordinary rolling bearings are allowed to be properly deflected. In order to prevent excessive deflection, when two bearings or multiple bearings are used to support the same part, the coaxiality of each bearing housing hole is first corrected by standard shaft and standard bearing. The correction method can adopt the shake axis method.