Bearing clearance can work is an important factor, divided into axial clearance and radial clearance. Select the appropriate clearance, can load in a reasonable distribution between the bearing rolling elements; limit the axis (or housing) axial and radial displacement of the axis of rotation to ensure accuracy; make the bearings at the specified temperature under normal work; reduce vibration and noise, help to improve bearing life. Therefore. In the selection of the bearing, you must select the proper bearing clearance.
Select the bearing clearance, should consider the following aspects:
1 bearing operating conditions such as load, temperature, speed, etc.;
(2) on the bearing performance requirements (precision rotation, friction torque, vibration, noise);
3 bearings and shaft and housing bore is caused when the interference fit bearing clearance decreases;
4 bearing work, the temperature difference between the inner and outer rings resulting bearing clearance decreases;
5 due to the shaft and housing materials with different coefficients of expansion, leading to decrease or increase the bearing clearance.
According to experience, the most suitable ball bearing clearance work is close to zero; roller bearings should be maintained with a small amount of clearance work. Good rigidity of the required supporting member, the bearing to allow a certain preload value. Here in particular that the so-called clearance work, refers to the actual operating conditions in the bearing clearance. There is also a clearance called primitive clearance refers to the bearing clearance before installation. Clearance than the original installation clearance. Our selection of clearance, the main task is to select the appropriate clearance.
National standards for clearance values are divided into three groups: a basic group (group 0), a small clearance auxiliary group (group 1 and 2) and a large clearance auxiliary group (3,4,5 group). Selected, under normal operating conditions, should give priority to the use of basic group, you can get the right bearing clearance work. When the basic group can not meet the requirements, you should use the auxiliary group of clearance. Large clearance auxiliary group for bearing and shaft and housing bore interference fit, a larger temperature difference between inner and outer ring bearing, deep groove ball bearings need to bear large axial load or the need to improve aligning performance, the heart and requirements and to improve speed limit reduce the bearing friction torque and other occasions; small auxiliary group for clearance requires high rotational accuracy, should be strictly controlled housing bore of the axial displacement and the need to reduce vibration and noise of the occasion.