Installation and adjustment of high-speed bearing:
1. The fit and clearance of high-speed bearing since high-speed bearing should meet both the requirements of high-precision bearing and high-temperature bearing, the following two points should be considered when considering its fit and clearance:
(1) size change and hardness change from normal temperature to high temperature;
(2) the change of force system and shape caused by centrifugal force at high speed.
In short, under the condition of high speed and high temperature, it is difficult to keep the precision and working performance of the bearing from the choice of fit and clearance.
In order to ensure that the raceway deformation after bearing installation is small, the interference fit cannot be too large, and the centrifugal force under high speed and thermal expansion under high temperature, or to offset the normal pressure on the matching surface.Or to loosen the mating surface, so the interference must be carefully calculated under the premise of considering the above two factors, the effective interference at normal temperature and normal speed for high-speed bearings may be invalid.
If the calculation result is too big (usually only under the condition of ultra-high speed), only the dual lubrication measures of the combination of ring lubrication method and hydrostatic lubrication method are adopted, and this scheme may make the DMN value of the bearing break through the mark of 3 million.
Thermal expansion at high temperature, or to offset the normal pressure on the surface.Or to loosen the mating surface, so the interference must be carefully calculated under the premise of considering the above two factors, the effective interference at normal temperature and normal speed for high-speed bearings may be invalid.
If the calculation result is too big (usually only under the condition of ultra-high speed), only the dual lubrication measures of the combination of ring lubrication method and hydrostatic lubrication method are adopted, and this scheme may make the DMN value of the bearing break through the mark of 3 million.
When considering the high-speed bearing clearance, not only the above factors should be considered, but also the influence of the thermal elongation of the shaft on clearance. It is required that the bearing has the best clearance under the working condition, that is, under the working temperature, and this clearance is formed under the condition of precise alignment of the center of the inner and outer ring groove.Because high speed bearings strive to reduce relative sliding and internal friction, it is best not to adopt the method of relative axial dislocation of the inner and outer rings to adjust the clearance of ball bearings.
When considering the interference and clearance of the bearing, we should pay attention to the characteristics of the material that becomes soft and easy to deformation at high temperature, and the possibility of permanent deformation caused by the temperature change from normal temperature to high temperature for many times.
0010010 nbsp;
2. Requirements for main engine related parts
High-speed bearing requirements bearing in rotary system after dynamic balancing precision, shaft and hole bearing installation of the parts should be higher than the general requirements of dimensional accuracy, form and position accuracy, especially the alignment of hole or shaft neck and shoulder verticality, and considering these problems, also must pay attention to the high speed and high temperature factors in the operation of the bearing.
In order to overcome this contradiction, measures such as reducing the surface roughness and improving the surface strengthening can be taken to improve the supporting stiffness, and hollow shaft can be used to reduce the system quality.