Cognitive bearing clearance
Bearing clearance, also known as the bearing clearance, is the distance between the bearing inner ring and the outer ring that can be freely offset from one another, meaning that when the bearing is not mounted on the shaft or bearing housing, the inner ring or the outer ring is fixed on one side and then The amount of movement when the bearing clearance is not fixed is the radial or axial movement.
Clearance Detailed and its choice
According to the direction of movement, can be divided into radial clearance and axial clearance. Fit to a specific device or equipment operation clearance called work clearance, its size and bearing fatigue life, temperature rise, noise, vibration and other properties have a significant impact, and with the nature of the load varies.
Radial clearance assumes non-preload condition and withstands radial load. Radial clearance physical meaning, any radial direction along the radial direction, the outer ring in the absence of external load relative to the inner ring from the radial eccentric limit position, the radial distance to the opposite extreme arithmetic mean.
Axial clearance assumes non-preloaded conditions and is capable of withstanding axial loads in both directions. Axial Clearance Physical Meaning The average value of the axial distance of one ferrule relative to the other ferrule from one axial limit to the opposite limit.
The original clearance bearing is not installed before the clearance.
The clearance value group is divided into three groups according to the size: the basic group, the small clearance group and the big clearance group. Japan's NSK, NTN and other brands there is a special CM group (motor clearance).
Clearance value selection principle Under normal working conditions, priority should be given to the basic group; large clearance group for the inner and outer rings with a larger amount of interference, or the temperature difference between the inner and outer ring, deep groove ball bearings need to bear the larger axis The load or need to improve the performance of self-aligning, or need to increase the bearing limit speed and reduce the bearing friction torque and other occasions; small clearance group for more high rotation accuracy, the need for strict control of the housing bore axial displacement, and the need to reduce Vibration and noise of the occasion.
Bearing clearance factors
Select bearing clearance, you must give full consideration to the following main factors:
(1) The tightness that the bearing cooperates with the shaft and shell hole will lead to the change of the bearing clearance value. General bearing installation will reduce the clearance value;
(2) During the operation of the mechanism, the temperature difference between the inner ring and the outer ring due to the different cooling conditions of the shaft and the outer shell will lead to the reduction of the clearance value.
(3) As the expansion coefficient of the shaft and the shell material due to different, will lead to reduce or increase the clearance value.
Motor bearing special
Different bearing manufacturers with the actual needs of the motor in the development of motor bearings. In fact, we are more concerned about the bearing clearance, and motor parts tolerance will directly affect the work of motor clearance, the market for motor development C3M clearance, is set for the motor C3 Clearance range, but concentrated in the lower tolerance of the special bearing clearance, relative to the C3 clearance, C3M tolerance band to narrow, better consistency.
Bearing clearance and motor parts matching is the key to bearing system processing, parts processing consistency of enterprises, the bearing clearance range can also be narrowed, or only by expanding the bearing clearance to adapt to the motor parts.