Overview of the axial clearance of roller bearings

Axial clearance is an important technical index in the application of double and four-row tapered roller bearings, which has a direct impact on the service life of the bearing. JB/T8236—2010 "Rolling bearing double-row and four-row tapered roller bearing clearance and adjustment methods "The conversion and adjustment methods of the radial clearance and axial clearance of double and four-row tapered roller bearings are specified, that is, the split measurement method. The clearance of double and four-row tapered roller bearings is too small, which is likely to cause serious bearing failure accidents. The main engine users often need to recheck the axial clearance and measure the double and four-row tapered rollers according to the "split method" specified in the standard. When bearing axial clearance, a height gauge is used to determine the distance between the end face of the ring and the measurement platform. The requirements for the bearing test platform are high, and it is difficult for users to achieve it on site. Manufacturers and users of the main engine have explored various alternative measurement methods in practical applications. The "whole method" is currently an alternative measurement method widely used by users of the main engine. The measurement practice shows that when measuring the axial clearance of double and four-row tapered roller bearings , The measurement error of "Integral Method" and "Split Method" is about 0.01~0.10mm1. The difference in the measured values ??obtained by different measurement methods forces bearing manufacturers to increase the axial clearance value to "match" the user's measurement method when configuring the clearance, causing the actual bearing clearance to be greater than the measured value, thereby reducing the rotation accuracy of the bearing and increasing the bearing Vibration and noise during operation will ultimately reduce the life of the bearing.

Some foreign companies have adopted the "projection method" when measuring the clearance of double and four-row tapered roller bearings without spacers, and have developed special measuring instruments, as shown in Figure 1. The calculation principle of this measurement method is the same as the "split method" stipulated by the standard. The end face of the ferrule is positioned in the measurement, without reciprocating leveling; 3 meter frames are read at the same time, and 3 sets of 9 data can be obtained by measuring 3 times; measurement The efficiency is greatly improved, and the accuracy requirements of the measurement platform are relatively low, which is convenient for measuring on the bearing application site. At present, this measurement method has been extended to the clearance measurement of double and four-row tapered roller bearings of various structural types.

To sum up, learn from the principle of the "protrusion method" measuring instrument of foreign companies, make simple tooling to carry out double and four-row tapered roller bearing axial clearance test experiments, and conduct a comparative analysis of the results obtained by different measurement methods.

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Measurement methods

In order to verify the data difference between the "projection method" and the standard "split method" and "integral method", 32930 single row tapered roller bearings (face-to-face pairing) and SKFBT2 with clearance to be fitted after remanufacturing [10] are selected -8131 double-row tapered roller bearings, measure the gap between the outer rings of the two types of bearings and calculate the axial clearance 12. The number of test samples are as follows: 100 sets of 32930 pairs are randomly selected to be 50 sets of 32930DF, 20 sets of SKFBT2-8131, and the tested bearing structure is shown in Figure 2. The external dimension of 32930DF is Φ150mm×Φ210mm×76mm, and the mass is 7.6kg; the external dimension of SKFBT2-8131 is Φ460mm×Φ860mm×380mm, and the mass is 975kg. The main reason for selecting these two types of bearings as the test objects is that the bearing gap is in the outer ring, which is convenient for overall measurement, and the difference between the weight and cone angle of the bearing is also large, which is convenient for data comparison. The test data comes from the measured values ??when the clearance between the working procedures is combined.