Selection of bearing clearance, should consider the following aspects:
1 bearing working conditions, such as load, temperature, speed, etc.;
2 requirements on the performance of the bearings (rotary precision, friction torque, vibration, noise);
3 bearing and shaft and shell holes for the interference fit resulted in reduction of bearing clearance;
4 bearings, the inner and outer rings of the temperature difference leads to reduction of bearing clearance;
5 because the expansion coefficient of shaft and shell of different materials, resulting in the decrease or increase of bearing clearance.
According to experience, the most suitable ball bearing clearance is nearly zero; roller bearing should keep a small amount of work clearance. FAG bearing allows for a certain amount of preload in a component that requires good support. It pointed out that the so-called work clearance refers to the bearing clearance in actual operation conditions. There is a clearance called the original clearance refers to the bearing without clearance. The original clearance is greater than the installation clearance. We choose the clearance, the main work is to choose appropriate clearance.
National standard clearance value is divided into three groups: a basic group (group 0), small clearance support group (1, 2 group) and large clearance support group (3, 4, 5 group). When the choice, under normal operating conditions, should give priority to the use of basic groups, can make the bearing clearance work properly. When the basic group can not meet the requirements, should use the auxiliary clearance. Large clearance group of auxiliary application on the bearing and the shaft and housing bore by interference fit, inner and outer rings of the bearing temperature difference is large, deep groove ball bearings need to bear large axial load or the need to improve the self-aligning capability, heart and improve the speed limit and reduce the NSK bearing friction torque and other occasions; small clearance support group for to require a higher rotation accuracy, strict control of the axial displacement of the shell hole, and need to reduce the vibration and noise of the occasion.
1 bearing the fixed
After determining the type and type of the bearing, it is necessary to carry out the design of the combined structure of the rolling bearing, in order to ensure the normal work of the TIMKEN bearing.
The combination of bearing structure design includes:
1) shaft supporting structure;
2) bearing and related parts;
Lubrication and sealing of the bearing 3;
4) increase the stiffness of the bearing system.
1 ends fixed (both ends of a one-way fixed)
Under ordinary temperature short axis (span L<400mm) and fulcrum of often used at both ends of the one-way fixed way, each bearing respectively bear the axial force in a direction. As shown, to allow the work of a small amount of thermal expansion, bearing installation should be left with the axial clearance 0.25mm-0.4mm (clearance is very small, do not have to draw the structure diagram), the amount of clearance is commonly used to adjust the adjustment screw.
Features: limit the axis of the two-way movement. Shaft suitable for working temperature change.
Note: considering the heat elongation, the gap between the bearing cover and the outer end is C, c=0.2~0.3mm.
2 end two-way fixed, one end of the walk
When the axial longer or higher operating temperature, axial thermal expansion shrinkage is larger, should end with two-way fixed, swim end fulcrum structure, as shown in figure.
The fixed end is subjected to biaxial axial force by a single bearing or bearing group, and the swimming end ensures that the shaft can be freely moving. In order to avoid loosening, bearing inner ring and shaft winding should be axially fixed (usually with circlips). When moving fulcrum of cylindrical roller bearings, Koyo bearing outer ring to and base is axially fixed, by moving between the roller and the ring to ensure free flexing of the shaft.
Features: a two-way fixed point, the other fulcrum for axial swimming.
Deep groove ball bearing as a moving fulcrum, the outer ring of the bearing end cover gap.
Cylindrical roller bearing as the pivot point, the outer ring of the bearing should be fixed.
Suitable for: long axis of temperature change.
