How To Install The Self-Aligning Bearing
How To Install The Self-Aligning Bearing
2022年1月1日
Disassembly Methods Of Various Types Of Timken Bearings
Disassembly Methods Of Various Types Of Timken Bearings
2022年1月1日

Installation Of Precision Nsk Bearing

Precision Nsk Bearing

1. Requirements for matching parts of precision NSK bearing

Due to the precision NSK bearing itself, the accuracy is within 1 μ M, so the matching parts (shaft, NSK bearing seat, end cover, retaining ring, etc.) are required to have high dimensional accuracy and shape accuracy, especially the accuracy of mating surface should be controlled at the same level as NSK bearing, which is very important and easy to be ignored.

It must also be noted that if the matching parts of the precision NSK bearing fail to meet the above requirements, the error of the precision NSK bearing is often several times or even more than 10 times greater than that of the original NSK bearing after installation, which is not a precision NSK bearing at all. The reason is that the error of the matching parts is often not simply superimposed on the error of the NSK bearing, but amplified by different multiples.

2. Fit of precision NSK bearing

In order to ensure that NSK bearing will not produce excessive Precision Nsk Bearing deformation after installation, the following must be done:

(1) The roundness of shaft and seat hole and the perpendicularity of retaining shoulder shall be in Precision Nsk Bearing accordance with the corresponding accuracy requirements of NSK bearing.

(2) It is necessary to accurately calculate both the interference of Precision Nsk Bearing the rotating ferrule and the appropriate fit of the fixed ferrule.

The burning interference of rotating ferrule should also be small within the possible range. As long as the effect of thermal expansion at working temperature and centrifugal force at high speed are ensured, the creep or sliding of tight fitting surface will not be caused. According to the working load and NSK bearing size, the fixed ring selects a very small clearance fit or interference fit. Too loose or too tight is not conducive to maintaining the original accurate shape.

Installation Of Precision Nsk Bearing

(3) If NSK bearing operates at high speed and the working temperature is high, special attention shall be paid to the matching of rotating ring not to be too loose to prevent eccentric vibration, and the matching of fixed ring shall not have clearance to prevent deformation and vibration of ring under load.

(4) The condition of small interference fit for the fixed ring is that both sides of the matching surface have high shape accuracy and small roughness, otherwise it will be difficult to install and more difficult to disassemble. In addition, the influence of thermal elongation of the main shaft needs to be considered.

(5) The spindle with paired double angular contact ball NSK Bearings has a light half load. If the fit interference is too large, the internal axial preload will be significantly too large, resulting in adverse effects. The spindle of double row short cylindrical roller NSK bearing and tapered roller NSK bearing have relatively large load, so their fit interference is also relatively large.

3. Methods to improve the actual matching accuracy

In order to improve the actual fitting accuracy of NSK bearing during installation, the measurement methods and tools that do not deform NSK bearing must be used to accurately measure the fitting surface dimensions of inner hole and outer circle of NSK bearing.

All the measurement items related to inner diameter and outer diameter can be measured, and the measured data can be comprehensively analyzed, Size of NSK bearing installation position precisely matched with shaft and seat hole. When actually measuring the corresponding size and geometry of the matched shaft and seat hole, it shall be carried out under the same temperature conditions as when measuring NSK bearing.

In order to ensure a high actual matching effect, the roughness of the surface matching the shaft and seat hole with NSK bearing shall be as small as possible.

During the above measurement, two groups of marks indicating the direction of large deviation shall be made on the outer circle and inner hole of NSK bearing and the corresponding surface of shaft and seat hole on both sides close to the assembly chamfer, so that the large deviation of matching two sides can be aligned in the same direction during actual assembly, so that the deviation of both sides can be partially offset after assembly.

The purpose of making two groups of orientation marks is to comprehensively consider the compensation of deviation, not only improve the rotation accuracy of the supports at both ends, but also partially eliminate the coaxiality error of the seat hole between the two supports and the journal at both ends. The surface strengthening measures for the mating surface, such as sand blasting and plugging the primary inner hole with a slightly larger diameter precision plug column, are conducive to improving the mating accuracy.