After the installation of deep groove ball bearings in the host, there is a measurement index called cyclic rotation accuracy. This kind of change approximately repeats the required number of revolutions, representing the "quasi period" of cyclic rotation accuracy. If the magnitude of the change within the quasi period is large, it is called poor cyclic rotation accuracy. When appropriate preload is applied to the main shaft of deep groove ball bearings, the speed can gradually increase to approach the working speed to implement the "running in" effect of the bearings, which can improve the cyclic rotation accuracy of the main shaft.
There is currently a precision instrument for improving the accuracy of deep groove ball bearings. When the main shaft uses 6202/P2 type bearings, but its accuracy still cannot meet the requirements, the shaft neck is thickened and a raceway is made on it to replace the inner ring. The steel balls are precisely measured and divided into groups of every three particles, with a spacing of nearly 120 ° between each group of steel balls. Due to the reduction of one processing surface and one fitting surface, the stiffness of the shaft bearing system is also improved. The close equidistant distribution of the larger and smaller three steel balls also improves the rotational accuracy of the shaft, thus meeting the accuracy requirements of the instrument.

Now let's introduce the comprehensive verification method for the installation accuracy of deep groove ball bearings. Firstly, the angular contact ball bearing is installed into the main shaft of the deep groove ball bearing. The verification of installation accuracy needs to go through the following four steps:
Firstly, measure the dimensions of the shaft and bearing seat holes to determine the precision of the bearing fit. The inner ring adopts interference fit with the shaft, and the outer ring adopts clearance fit with the bearing seat hole.
Secondly, the installation of the fixed end front bearing on the shaft: thoroughly clean the bearing with clean cleaning kerosene, and then fill a certain amount of lubricating grease into the bearing with an oil gun; Heat the bearing to raise the temperature by 20-30 ℃, and use a hydraulic press to install the bearing into the shaft end; Press the clamping sleeve onto the shaft and apply appropriate pressure to the bearing end face to position it axially; Roll the strap of the spring scale onto the outer ring of the bearing and verify whether there is a significant change in the specified preload by measuring the starting torque.
Again, install the deep groove ball bearing shaft assembly into the seat hole: heat the seat hole to raise the temperature by 20-30 ℃, and use continuous gentle pressure to install the bearing shaft assembly into the seat hole; Adjust the front cover, using the outer end face of the bearing seat as a reference, align the head of the dial gauge with the surface of the shaft neck, rotate the shaft to measure its runout, position the dial gauge on the shaft, align the head with the inner surface of the rear seat hole, and rotate the shaft to measure the coaxiality of the front and rear seat holes of the bearing seat.
Afterwards, selectively place the free end bearing in a position that may offset the deviation, install it at the support position behind the bearing seat, and try to offset the roundness deviation and coaxiality deviation between each other as much as possible.
Measure the actual fitting accuracy during the installation of deep groove ball bearings. At this point, it is necessary to use professional measurement methods and tools to accurately measure the fitting surface dimensions of the inner hole and outer circle of the bearing, measure all measurement items related to the inner and outer diameters, and conduct a comprehensive analysis of the measured data. Based on this, precisely match the dimensions of the bearing installation parts for the shaft and seat hole.
When measuring the corresponding dimensions and geometric shapes of the shaft and seat hole in the actual measurement, it should be carried out under the same temperature conditions as when measuring the bearing. To ensure a high practical fit effect, the surface roughness of the shaft and seat holes that match the bearings should be minimized as much as possible. When measuring, two sets of marks indicating the direction of larger deviations should be made on the outer circle and inner hole of the bearing, as well as on the corresponding surfaces of the shaft and seat hole, on both sides near the assembly chamfer. This is to align the larger deviations of the two matching parties in the same direction during actual assembly, so that the deviations of both parties can be partially offset after assembly. When considering the compensation of deviations comprehensively, the rotation accuracy of each end support is improved, and the coaxiality error between the seat holes and the two end shaft necks is partially eliminated.

• Previous：第一条
• Next：How to calculate the bearing fitting tolerance