In mechanical equipment such as precision machine tools, the accuracy requirements for bearings are usually particularly high. Therefore, YRT turntable bearings are mostly used. In most cases, in order to ensure the rigidity and accuracy of the bearings, preloading is carried out on the bearings. Here, the editors of Guoyang Precision Machinery have compiled the preloading methods of YRT turntable bearings for your reference.
The radial preloading method is mostly applied to bearings that bear radial loads. A nut is used to adjust the axial position of the bearing relative to the journal, so that the inner ring has an appropriate expansion amount to obtain a radial negative clearance. This method is mostly used in the main shafts of machine tools.
The axial preloading method can be roughly divided into two types: position preloading and constant pressure preloading:
(1) Position Preloading
In position preloading, an appropriate amount of preloading can be obtained by adjusting the size of the bushing or shim. It is also possible to adjust to an appropriate preloading by measuring or controlling the starting friction torque. Additionally, bearings with pre-adjusted preloading amounts can be directly used to achieve the purpose of preloading. In this case, generally, no further adjustment is required. For any bearing that has undergone axial preloading, its relative position will definitely not change during use.
(2) Constant Pressure Preloading
Constant pressure preloading is a method of obtaining appropriate preloading for bearings by using helical springs, disc springs, etc. Generally, the rigidity of the preloading spring is much smaller than that of the bearing. Therefore, the relative position of the bearings with constant pressure preloading will change during use, but the preloading amount remains roughly the same.
1. When the preloading amount is equal, position preloading has a greater effect on increasing the rigidity of the bearing, and the influence of the change in rigidity on the bearing load during position preloading is also much smaller.
2. During the use of position preloading, the preloading amount will change due to the influence of factors such as the axial length difference caused by the temperature difference between the shaft and the bearing housing, the radial expansion amount caused by the temperature difference between the inner and outer rings, and the displacement caused by the load. However, during the use of constant pressure preloading, the change in preloading can be neglected.
The above are the preloading methods of YRT turntable bearings compiled by the editors of Guoyang Precision Machinery. Even if the preloaded bearings bear relatively large loads, they will not undergo significant deformation, which is very beneficial for extending their service life.