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1: Bearing grease injection method: Influence of the am […]
1: Bearing grease injection method:
Influence of the amount of grease injection on sealing performance A large number of tests have proved that when the amount of grease injection is less than about 30% of the internal cavity volume of the bearing, since the grease in the bearing does not reach a saturated state, the grease leakage is very small. When the amount of grease injection exceeds 30%, the inside of the bearing is partially saturated. When the amount of grease injection reaches 50%, the grease in the bearing reaches a fully saturated state, and the excess grease is "squeezed" out. Pay special attention, sometimes although the grease is not injected much, the grease injection method is not standardized and scientific, resulting in uneven grease in the bearing cavity, local saturation in the bearing, and early rapid "extrusion" phenomenon.
As for the homogenizing process, it is suggested that the speed may be increased a little. The sealed bearing test and the test method for evaluating the sealed bearing are developed for the different performance characteristics and uses of the sealed bearing. The focus is different, and the test content is different, but each performance test is an important special study. At the same time, the sealed bearing test and evaluation method is a very important means to verify and improve the design and quality control.
2: Bearing stiffness:
1. The stiffness of the bearing depends on its type and size. The main judging criteria are: roller element type (eg spherical or cylindrical), number and size of rollers and contact angle.
2. The influence of the contact angle on the stiffness is generally that the contact angle is small, the radial stiffness is high; the contact angle is large, the axial stiffness is high. When arranging bearings, mounting two or more bearings in the same location can increase stiffness. Angular contact ball bearings are best suited for this use and are often used in pairs.
3. Bearing stiffness is expressed as the ratio of elastic deformation under load to the degree of recovery. Since the elastic recovery of rolling bearings is not linearly related to the load, it is difficult to describe it with a single function; in applications, a linear relationship can be used to make an approximate estimate.
4. The bearing stiffness is also affected by the main shaft and the bearing seat, and the matching tolerance should be selected carefully; the stiffness of the matched bearing set will also be affected by the preload.
5. The effect of the number of rollers on the stiffness is greater than that of the bearing size. Increasing the number of rollers by the same percentage increases the bearing stiffness more than increasing the bearing size. For this reason, precision rolling bearings increase their rigidity by increasing the number of rollers.