When the radial spherical plain bearing adopts interference and transition fit, due to a certain amount of interference, the mating surfaces will be flattened against each other, which will cause the expansion of the inner ring and the shrinkage of the outer ring of the radial spherical plain bearing. The radial clearance is reduced. In theory, due to the wide distribution of effective interference conditions when the two tolerances intersect, it is quite difficult to accurately calculate the change in radial clearance. Based on the empirical data, a kind of radial clearance effect of the radial spherical plain bearing is given below.

A quick way to assess the impact.

1 Reduction of bearing radial clearance

1. 1 Expansion of the inner ring

The expansion of the inner ring after fitting is a = 0.9lib, (1) where: a is the expansion of the inner ring when it is matched with the shaft; li is the effective interference, see Table 1; b is the cross-sectional coefficient of the inner ring, See Table 2; 0. 9 Correction factor introduced to eliminate errors such as surface roughness and roundness of parts.

1. 2 Compression of the outer ring

For the annular bearing seat, when calculating the shrinkage of the outer ring after fitting, the expansion of the bearing seat must be considered. The expansion is mainly determined by its wall thickness, so the coefficient f is used to correct the shrinkage of the outer ring. The shrinkage of the outer ring after mating is e = 0. 9le cf, (2) where: e is the reduction of the outer ring; le is the effective interference, see Table 3; c is the cross-sectional coefficient of the outer ring, see Table 4; f is the expansion coefficient of the bearing seat. f is related to the wall thickness of the bearing seat and the cross-section of the bearing outer ring. According to the data obtained by experience, the numerical approximation method is adopted, and f is set as the cubic function of x. x = DA/DG (DA is the housing bore diameter and DG is the housing outside diameter). The formula for calculating f for different values of c is given below.

c = 0. 70, 

f = -0. 117x³ - 0. 54x² + 0. 083x + 0. 7; (3) 

c = 0. 81, 

f = -0. 558x³ +0. 027x²-0. 048x +0. 812; (4) 

c = 0. 83, 

f = -0. 75x³ + 0. 2x² - 0. 041x + 0. 825; (5) 

c = 0. 85, 

f = -0. 925x³ + 0. 39x² - 0. 084x + 0. 85. (6)

2 Calculation example

Taking the radial spherical plain bearing GE50ES-2RS as an example, assuming that the fit tolerance is M7/m6, the outer diameter of the bearing seat is 120 mm, the bore diameter of the bearing seat is 75 mm, and the shaft diameter is 50 mm, the original radial clearance of GE50ES-2RS is 0. 060～0． 120 mm, calculate the reduction in radial clearance after installation.

2. 1 Expansion of the inner ring

From Table 1, li = 0. 023 mm; b = 0 from Table 2. 79, then it can be calculated by formula (1)

a = 0. 9 × 0. 023 × 0. 79 = 0. 016 mm.

2. 2 Reduction amount of outer ring

From Table 3, le = 0. 009 mm; c = 0 from Table 4. 85, x = DA DG = 0. 625. From (6) we get f = 0. 72, then e = 0 is calculated from equation (2). 9 × 0. 009 × 0. 85 × 0. 72 = 0. 005 mm. Then the reduction of bearing radial clearance is a + e = 0. 021 mm.

3 Conclusion

Using the above method, the clearance of the radial spherical plain bearing before assembly can be selected in the design of the assembled rod end joint bearing, so that the clearance after assembly can meet the requirements of the standard;The user estimates the clearance of the radial spherical plain bearing after assembly.

L-P theory algorithm, which can predict bearing life more accurately. (2) The interference between the shaft and the inner ring and the temperature difference have a significant impact on the life of the bearing. Improper interference and temperature difference will seriously reduce the overall life of the bearing. (3) Combining the high-speed rolling bearing dynamic calculation software [6] and the fatigue life calculation program can better predict the life of high-speed cylindrical roller bearings under complex working conditions, which is conducive to selecting the best working condition parameters of the bearing. Radial load, interference, etc.