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  • Three Typical Bearing Configuration Forms

    Discussion in 'The Leisure Lounge' started by Michelle, Jun 24, 2020.

    1. Michelle

      Michelle Member

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      A shaft often requires two fulcrums, that is, two sets of rolling bearings for support. The bearing configuration just solves the problem of how the bearing on the fulcrum fixes the shaft system axially, and how to avoid the bearing from jamming after thermal expansion. Based on the understanding of bearing knowledge, Zhonghua Bearing Network shares the typical knowledge of bearing configuration and hopes to help everyone. 24072BK30.MB FAG bearing.



      Before we configure, we must understand some points related to bearings:


      [​IMG]


      1. The expansion and contraction of the shaft caused by temperature changes.



      2. The bearing is easy to install and disassemble.



      3. The tilt of the inner and outer rings due to shaft deflection and installation errors.



      4. The reading and preloading method of the entire rotating system including bearings.



      5. Bear and transfer the load at the most suitable position.





      Avoid bearing jamming, understand three typical bearing configuration forms:



      1. The two pivots are fixed in one direction



      This configuration is to allow each fulcrum to axially fix the shaft system in one direction. The shortcomings are: because the two fulcrums are fixed by the bearing cover, so when the shaft is heated and elongated, it will inevitably cause the bearing to be subjected to an additional load and affect the service life. Therefore, this form is only suitable for occasions where the working temperature rise is not high and the shaft is short (span L≤400mm). For deep groove ball bearings, an axial gap C should also be left between the outer ring of the bearing and the bearing cover, and C = 0.2 ~ 0.4 mm should be taken to compensate for the thermal elongation of the shaft. Because the gap is small, it can not be drawn on the drawing. For angular contact bearings, the thermal compensation gap is guaranteed by the internal clearance of the bearing.


      [​IMG]


      2. One point is fixed in both directions, the other point moves



      For a fixed fulcrum, deep groove ball bearings can be used when the axial force is not large, and the left and right sides of the outer ring are fixed. The upper half of the figure is fixed by the shoulder of the bearing housing hole. This structure prevents the housing hole from being boring at one time, affecting the processing efficiency and coaxiality. When the axial force is small, the outer ring can be fixed by the elastic ring, as shown in the lower part of the figure. In order to withstand the axial force to the right, the inner ring of the fixed fulcrum must also be axially fixed. For the floating fulcrum, deep groove ball bearings are often used, and cylindrical roller bearings can also be used when the radial force is large, as shown in the lower part of the figure. When using deep groove ball bearings, there is a large gap between the outer ring of the bearing and the bearing cover, so that the shaft can be freely extended when thermally expanded, but the inner ring needs to be fixed axially to prevent the bearing from loosening. When the cylindrical fulcrum is used as the fulcrum, because the inner and outer rings can move relatively in the axial direction, the inner and outer rings should be fixed axially to avoid excessive displacement of the outer ring. When designing, it should be noted that there is no unnecessary or insufficient axial fixation of the inner and outer rings of the bearing.



      The fixed fulcrum adopts two angular contact bearings arranged symmetrically, respectively bears the axial force in the left and right directions, and jointly bears the radial force, which is suitable for the occasion with large axial load. In order to facilitate assembly adjustment, the fixed fulcrum adopts the sleeve structure. At this time, when selecting the size of the floating fulcrum bearing, the outer diameter of the bearing and the outer diameter of the sleeve should generally be equal to facilitate the processing of the two bearing seat holes.



      3. Swimming support at both ends



      When both fulcrums are designed as swimming supports, the position of the shafting components must be positioned by other measures. For example, the position of the shafting component supporting the herringbone gear can be determined by the geometry of the herringbone gear. At this time, the two fulcrums must be designed as a floating support, but used for the herringbone gear meshing with it (above) The shafting components must be fixed at both ends so that both shafts are positioned axially.
       
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