Views: 21 Author: Site Editor Publish Time: 2020-07-18 Origin: Site
Compared with ordinary bearings, precision bearings have higher accuracy level. The precision bearing has higher rotation accuracy and smaller size error than the common bearing. At the same time, the axial and radial runout of precision bearings are smaller than that of ordinary bearings.
Requirements of Precision Bearing for Matching Parts
As the precision of precision bearing itself is within 1 μm, it is required to have high dimensional precision and shape precision with its matching parts, especially the precision of mating surface should be controlled within the same level as that of bearing, which is very important, but it is also easy to be ignored.
Fit of Precision Bearing
In order to ensure that the bearing does not produce excessive deformation after installation, the following requirements must be met.
1. The roundness of shaft and bearing seater hole as well as the perpendicularity of retaining shoulder shall be in accordance with the corresponding accuracy of bearing.
2. It is necessary to accurately calculate both the interference of rotating ring fit and the matching quantity of fixed ring.
3. If the shaft bearing runs at high speed and the working temperature is high, special attention should be paid to the matching of the rotating ring to prevent eccentric vibration. Also note that the fit of the retaining ring must not have clearance to prevent deformation and vibration of the ring under load.
4. The condition for small interference fit of the retaining ring is that both sides of the matching surface have high shape accuracy and small roughness, otherwise it will be difficult to install and disassemble, and the influence of thermal elongation of the spindle should also be considered.
Method of Improving Actual Matching Accuracy
In order to improve the actual matching accuracy during the installation of precision bearings, it is necessary to measure the mating surface dimensions of inner bore and outer circle of bearings accurately by means of measuring methods and measuring tools that do not deform shaft bearings. Installation dimensions can be determined by measuring all items related to inside and outside diameters and comprehensive analysis of the measured data.
In order to ensure a higher actual matching effect, the surface of the shaft and the bearing seater bore matching the bearing should have as little roughness as possible.
During the above measurements, two sets of markings shall be made on the outer and inner bores of the bearings and on the corresponding surfaces of the shafts and bearing seater holes to indicate the direction of maximum deviation, respectively, so that the maximum deviation of the two matching sides can be aligned in the same direction during actual assembly, after assembly, the deviation of both sides can be partially offset.
The purpose of making two sets of orientation marks is to make comprehensive consideration of compensation for deviations, so as to improve the rotation accuracy of each support at both ends and to partially eliminate the coaxiality errors of seat holes and journals at both ends. Surface strengthening measures such as sand blasting can improve the matching accuracy.