Installation and adjustment

Time：2020.09.22  Source：Roller Bearings Suppliers

1. Since high-speed bearing needs to meet the requirements of high-precision bearing and high-temperature bearing, the following two points should be taken into account when considering the mounting fit and clearance of high-speed bearing:

(1) Change in size and hardness from room temperature to high temperature;

(2) Changes in force system and shape caused by centrifugal force at high speed.

In short, the choice of fit and clearance should be made to maintain the accuracy and performance of the bearing under the condition of high speed and high temperature, 

In order to ensure a small deformation of the installed bearing’s raceway, the interference selection of angular contact ball bearings in high-speed bearing can't extra big, because of the centrifugal force in high speed will offset the normal pressure on the surface, or thermal expansion in high temperature, may cause the fitting surface relaxation, Therefore, the interference fit must be calculated prudently while the above two factors are considered,. The effective interference at normal temperature and constant speed may be invalid for high-speed bearings.

If the contradiction between the two calculation results is too great (usually only in the case of ultra-high speed), only the dual lubrication measures of under-ring lubrication and static pressure lubrication can be adopted, and this scheme may make the DMN value of the bearing exceed 3 million.

When considering the clearance of high-speed bearing, not only the above factors, but also the influence of the thermal elongation of the shaft on the clearance should be considered. It is required that the bearing should work under normal conditions, that is, there is the best clearance under the working temperature, and this clearance is formed under the state of accurate alignment of the center of the ball groove in the inner and outer rings.

In order to reduce the relative sliding and internal friction of the high-speed bearing, when considering the fit interference and clearance of the bearing, more attention should be paid to the feature that the material becomes soft and easily deforms at high temperature, as well as the possibility of permanent deformation caused by multiple temperature changes from normal temperature to high temperature.

2. Requirements for relevant parts of the main engine

For high-speed bearing in rotary system after adjusting for precision of the dynamic balance at the hole axis and the installation of bearing parts should be higher than the general requirements of dimensional accuracy, form and position accuracy, pay special attention to alignment of hole or shaft neck and shoulder verticality, and considering the problems at the same time, must pay attention to the high speed and high temperature factors in the operation of the bearing.

In order to overcome the contradiction of requiring both high rigidity and light quality of the shaft supporting system, measures such as reducing surface roughness and strengthening surface hardness can be taken to improve the stiffness of the shaft supporting system, and hollow shafts can be used to reduce the quality of the shaft system.