When designing a new spindle, before selecting INA bearings, the spindle performance parameters should be considered first, the key performance should be roughly determined, and then the further probe should be carried out. (including: spindle speed, spindle accuracy, spindle rigidity, spindle life, spindle heating, spindle reliability)
After determining the spindle parameters, the actual size of the gauge spindle (axle diameter, length, bearing span).
According to the bearing form (ball or cylindrical roller bearings), collocation (collocation number), driving mode (transmission belt, gear, motor, built-in motor), lubrication (oil, oil, oil mist, injection) and other spindle parameters set to determine its structure.
1, bearing radial load
The main INA bearing bearing radial load is centripetal bearing. The nominal contact Angle a0 of this kind of bearing is <=450. The roller bearing with the same ruler rain can bear more radial load than the ball bearing.
Type N and type NU cylindrical roller bearings can only bear radial loads, other types of centripetal bearings can bear both radial and axial loads.
2. Axial load of bearings
The main bearing axial load is generally thrust bearing, its nominal contact corner a0>450. Thrust bearings and thrust angular contact ball bearings can bear one or two axial forces at the same time according to their different structures. When the bearing force is particularly high, the thrust cylindrical roller bearing and thrust aligning roller bearing are preferred.
Thrust aligning roller bearings and unidirectional thrust angular contact ball bearings can bear both axial and radial loads, while other thrust bearings can only bear axial loads.
3. Length compensation of the bearing itself
The structure that supports a shaft and bearing is usually a combination of fixed bearing and swimming bearing. Swimming INA bearings compensate for shaft length error and thermal expansion.
NU type and N type cylindrical roller bearings are ideal swimming bearings, which can compensate for the length themselves. The inner and outer rings of bearings can be fitted tightly.
4. Length compensation of sliding fit
Non-separable bearings can also be used as walking bearings. One of the two rings of this kind of bearing is fitted and has no axial fixed surface. Therefore, one of the bearing rings can move on its supporting surface.
After determining the size and type of precision bearings, the specific design of bearings should be considered.
Fully consider bearing fatigue life, rigidity, heating and other factors, select the most appropriate bearing clearance (pre-load).
Because bearing clearance and preload are the most critical to INA bearing performance, the more high-speed operation is more critical, so it must be carefully considered. If not chosen, problems such as early damage or sintering will occur. It is necessary to go back and forth from step 4 to step 3, or from step 4 to step 2.
After determining the spindle structure design, the necessary conditions for actual installation should be considered.
Confirmation of the precision, tolerance fit, tightening force of the fixing nut required for the installation and fixing of the installation shaft and bearing seat of high-precision bearings, and the pre-load and internal clearance of INA bearings after actual installation.