The accuracy of precision bearing after installation

 The accuracy of precision bearing after installation

1. Accuracy improving method

Bearing in the host after the installation, such as the measurement of spindle radial runout, slide bearing found its each turn of measuring value has a certain change; Continuous composite bearing measurement, can be found that after a certain number of revolution, this change will approximately duplicated. Measure for cyclic rotation accuracy degree of the change, change the approximately duplicated the revolution, on behalf of cyclic rotation accuracy "cycle", the value of the amplitude changed in quasi cycle, is the cycle rotation accuracy is poor.

Such as the proper preload on the spindle, the speed rise gradually to the oilless bearing speed close to work, on bearing the "break-in" effect, can improve the circulation of the spindle rotation accuracy.

2. A method for increasing accuracy of bearing

Manufacture precision instruments in one power plant, the type 6202 / P2 bearing spindle and its precision is still cannot meet the requirements, the bold shaft neck and on the race to replace the inner ring, and the steel ball, the measurement of waxy secret, to size every three grain of a group, each group of steel ball are separated pick up close to 120 °, due to reduced a heavy processing surface, reduce the heavy blend surface, at the same time improve the axial stiffness of the bearing system, and the three largest grain and minimum three grain of steel ball nearly equidistant distribution, and improves the precision of drive shaft rotation, thus satisfying the requirements of the precision of the instrument.

3. The installation precision of the comprehensive check method

Install the angular contact ball bearing in the spindle, the precision of calibration as follows (diameter of axle as 60-100 - mm engine lathe as an example) :

(1) to measure the size of the shaft and bearing hole, to determine with precision of the bearing, cooperate with the requirements as follows:

Inner ring and the shaft to interference fit, interference of 0 ~ + 4 microns (at light load, high precision of 0); Outer ring and bearing hole clearance fit, the interval 0 ~ + 6 microns (but on the free end bearing with angular contact ball bearing, still can increase the clearance); Shaft and hole surface roundness error in under 2 microns, bearing the face of baffle used parallelism in under 2 microns, shaft shoulder end foreign face beat in under 2 microns; Axis bearing hole block shoulder to beat under 4 microns; Spindle axis inside the front cover end face beat under 4 microns.

(2) fixed end before the installation of the bearings on the shaft

Will the kerosene used to clean the bearing with clean thoroughly clean, for grease lubrication, to contain 3% ~ 5% of organic solvent injection bearing grease for degreasing, cleaning and quantitative grease oil gun will fill in the bearing inner (10% ~ 15%) of the bearing space volume. Heat bearing the heat up 20 ~ 30 ℃, using hydraulic press the bearing into shaft end; Will set casing pressure on the shaft and with appropriate pressure against bearing face makes its axial positioning; Will spring balance tape volume on the bearing outer ring, use the method of measuring start torque calibration of pre-loaded whether there is a substantial change (even if the bearing is correct, but due to cooperate or cage, the deformation of the preload also has the potential to change).

(3) the bearing - shaft assembly into a hole

Heating holes make up 20 ~ 30 ℃, with a continuous gentle pressure of bearing - shaft assembly into the hole; Adjust the front cover, make the front cover of the fastening quantity from 0.02 to 0.02 mu m, based on bearing outer end face, will dial gauge meter resistance on shaft neck surface, will beat measuring the rotation axis, request error under 10 microns. Will be located on the shaft, dial gauge meter resistance in the back seat hole surface, the axis of rotation to measure before and after bearing hole of the alignment.

(4) put free end bearing selectively may offset the position of the deviation, after installed on the bearing support position, offset each other as much as possible of roundness error and axiality deviation.

4. Cone Kong Shuang column short cylindrical roller bearing installation

Installation NN3000K Kong Shuang series cone column short cylindrical roller bearing, must pay attention to the bearing inside diameter and shaft taper fit correctly, in the case of production is less available coating contact check, but in the production batch is large, it is best to the taper gage calibration precision.

When install on the cone shaft bearings, inner ring should be along the axial adjustment to the appropriate position, make its radial clearance is close to zero.