1. Ways to Improve Shaft Support Rigidity Ways to improve shaft support rigidity can, in principle, be summed up in the following points: (1) Select high-rigidity bearings; (2) Use bearing application technology to improve support rigidity; (3) Properly adjust the main engine Structural parameters to improve support rigidity.
2. Select bearings from the perspective of support rigidity. The key to selecting bearings from the perspective of support rigidity is (1) The rigidity of roller bearings is higher than that of ball bearings; (2) The rigidity of large-sized bearings is higher than that of small-sized bearings, even if Bearings with the same diameter but larger width have higher rigidity than bearings with smaller width; (3) Bearings with more rolling element particles and bearings with more rows have better rigidity; (4) Bearings with adjustable clearance , which is conducive to improving the support rigidity i (5) If necessary, bearings without inner rings, outer rings or inner and outer rings can be used to reduce deformation links and increase the number of rolling element particles.
3. Application technology to improve shaft support rigidity Application technology plays a great role in improving shaft support rigidity, which are summarized as follows: (1) Requirements for bearing matching surfaces. The lower the surface roughness of the bearing installation parts on the shaft and seat hole, the lower the surface roughness. The better the shape and position accuracy, the higher the support rigidity obtained. Applying surface strengthening treatment to the above surface will help improve the rigidity. Utilizing a high-hardness plug rod with very low roughness and gently pressing it into and out of the seat hole multiple times in a lubricated state with a certain interference will also help improve the support rigidity. If necessary, a snap ring can be used to perform similar treatment on the journal. . (2) Use the bearing preloading method to improve the support rigidity. The axial preloading method can be used for ball bearings or tapered roller bearings, and the radial preloading method can be used for short cylindrical roller bearings, which can significantly improve the rigidity of the shaft support. , at this time, either the bearing clearance is eliminated, or a small negative clearance is obtained. However, when the rotation speed is not too high and the temperature rise is not large, it is best to adjust it to a small negative clearance state. When applying preload, it is advisable to continuously measure the deformation. Note that in the low-value stage of deformation, the deformation is nonlinear with the increase of the preload load; while in the high-value stage, the deformation is linear with the increase of the load. Once the linear relationship between deformation and load appears, the increase in preload load will be stopped immediately. At this time, constant stiffness can be obtained. Thereafter, there is a fixed relationship between the axial rigidity and radial rigidity of the bearing, independent of external load. The above-mentioned deformation can be measured by, for example, placing the dial indicator against the end face of the bearing or an appropriate part of the shaft and observing the change in the reading with the preload. The preloading method has its disadvantages, such as increasing the friction torque of the bearing, increasing the temperature rise, shortening the service life, etc. Therefore, we must consider it comprehensively, weigh the gains and losses, and select the appropriate preloading amount. (3) Bearing configuration The bearing configuration also has a great influence on the bearing rigidity. Generally speaking, for radial thrust ball bearings and roller bearings, when used in pairs, it is advisable to have the outer rings with their large end faces facing each other (that is, their pressure The pressure cone formed by the line is configured with the tip outward). In this way, the bearing has a greater ability to resist overturning torque, and its adjusted preload amount is less likely to change when the temperature changes. (4) Using a multi-bearing support method, if the axial position permits, each pivot point uses two or more bearings as radial support, which can improve the support rigidity. For example, recently in machine tool spindle components, several sets of radial thrust bearings installed with axial preload are widely used as shaft supports with the same fulcrum.
