How To Improve The Rigidity Technology Of Shaft Support

(1) For the bearing matching surface requirements, the lower the surface roughness and the better the shape and position accuracy of the bearing installation part on the shaft and seat hole, the higher the supporting rigidity will be. Surface strengthening treatment is applied to the surface to improve the rigidity. The use of very low roughness of high hardness plug, with a certain interference in the lubrication state of several times gently pressing into and out of the seat hole is also conducive to improving the rigidity of the support, if necessary, the collar can be used for similar treatment of the journal.

(2) The bearing preload method can be used to improve the bearing rigidity. The axial preload method can be used for ball bearings or tapered roller bearings, while the radial preload method can be used for short cylindrical roller bearings, which can significantly improve the rigidity of the shaft support. At this time, the bearing clearance is either eliminated or a small negative clearance is obtained. However, under the condition that the speed is not too high and the temperature rise is not large, it should also be adjusted to a small negative clearance state.

When preloading is applied, it is advisable to constantly measure its deformation. It is noted that in the stage of low deformation, the deformation is nonlinear with the increase of preloading. At the high value stage, the deformation is linear with the increase of load. Once there is a linear relationship between deformation and load, the increase of preload is stopped immediately, and a constant stiffness can be obtained at this time. Thereafter, there is a fixed relationship between axial rigidity and radial rigidity of bearings, independent of applied load.

The above deformation can be measured by, for example, pressing the dial meter head against the bearing face or an appropriate part of the shaft and observing its reading as it changes with preload. The preload method has its disadvantages, such as increasing the friction torque of bearings, increasing the temperature rise, shortening the life, etc., so it is necessary to consider comprehensively, weigh the gains and losses, and choose the appropriate preload.

(3) the configuration of bearings bearing configuration has a great impact on the rigidity of bearings. Generally speaking, for centripetal thrust ball bearings and roller bearings, in pairs, the outer ring large end face relative (that is, the pressure line formed by the pressure cone tip outward) configuration is adopted, so that the capacity of bearing anti-overturn torque is large. When the temperature changes, the adjusted preload also changes less.

(4) the use of multi-bearing support in the axial position allows the condition, each fulcrum using two or more bearings as radial support, can improve the support rigidity. Recently, for example, in the spindle parts of machine tools, several sets of centripetal thrust bearings are widely used as the shaft support of the same fulcrum.