How to choose the bearing

2018-08-17 14:18:13 zhongqi 5

How to choose the bearing


The selection of bearings can be started from the following aspects:


First, the load direction, size and nature


All radial bearings can withstand radial loads, all thrust bearings can withstand axial loads, and angular contact ball bearings and tapered roller bearings are available for radial and axial loads (combined loads).


The size of the load is usually determined by the size of the bearing. Bearings with larger dimensions can withstand relatively large loads. Generally, the bearing capacity of a roller bearing is larger than that of a ball bearing of the same size. Full-roller bearings can withstand heavier loads than the corresponding bearings with cages. Therefore, ball bearings are mostly used for medium or small loads. In the case of heavy loads and large shaft diameters, roller bearings are generally more suitable.


Angular contact ball bearings and tapered roller bearings need to be installed in pairs.


When the load is not acting on the center of the bearing, an overturning moment is generated. In this case, it is best to use double row bearings (such as double row deep groove ball bearings or double row angular contact ball bearings, etc.), or use face-to-face or back-to-back paired single row angular contact ball bearings or tapered roller bearings. Back-to-back bearings are more tolerant.


Second, the speed


Generally, the working speed of the bearing should be lower than the limit speed listed in the bearing model table. Deep groove ball bearings, angular contact ball bearings and cylindrical roller bearings have higher speed limits and are suitable for high speed operation. The thrust bearing has a lower limit speed.


Third, the support limit requirements


A shaft or other component of a rotating machine, usually supported by a fixed end bearing and a floating end bearing. A bearing that can withstand two-way axial loads can be used as an axial displacement in both directions of a fixed bearing limit. Bearings that can only withstand axial loads in one direction can be supported in one direction. The swimming support is not limited. It is optional to use the inner and outer ring inseparable radial bearings to swim in the bearing housing hole. It is also possible to use cylindrical roller bearings with inner and outer rings separable. The inner and outer rings can swim relative to each other. .


Fourth, the alignment performance


If the coaxiality of the two bearing housing holes or the deflection of the shaft is not guaranteed due to various possible reasons, the self-aligning ball bearing, spherical roller bearing and thrust spherical roller bearing with good self-aligning performance should be selected. It can withstand the angular error generated under load and compensate for the initial error caused by machining or installation errors. Deep groove ball bearings and cylindrical roller bearings cannot withstand any angular error.


V. Stiffness requirements


The stiffness of a rolling bearing is the degree to which the bearing is elastically deformed under load. This deformation is generally small and can be ignored. However, in some applications, such as bearings for machine tool spindles or pinion bearings, stiffness is very important.


Generally, the rigidity of the roller bearing is large, and the rigidity of the ball bearing is small. Angular contact ball bearings and tapered roller bearings use a pre-tightening method to increase the rigidity of the support.


Sixth, other


Needle roller bearings or needle roller and cage assemblies are available where radial space is limited; low noise deep groove ball bearings are available for bearing vibration and noise requirements; bearings requiring high rotational accuracy (eg machine tools) For spindles and for applications with high speeds, bearings with higher precision than normal grades should be used.


Finally, it is also important to emphasize the economics and market availability when selecting the type of bearing.


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