Introduction to the installation method of angular contact ball bearings

According to the structural type of the bearing, the matching conditions with the shaft and the bearing seat, and the existing installation conditions, formulate the corresponding bearing installation method. No matter what installation method is used, one principle is that during the entire installation process of precision bearings, the rolling elements of the bearing must not be stressed.

The fit between the inner ring of the bearing and the shaft is generally an interference fit, while the outer ring and the bearing seat are mostly a clearance fit, and there is also a slight interference fit.

There are four commonly used methods for installing bearings on the main shaft, the details are as follows:

The method of using a hand hammer and a sleeve is mostly used for the installation of small and medium-sized bearings where the fit between the bearing ring and the journal or the bearing seat hole is not too tight. When selecting a sleeve, its size should correspond to the size of the bearing ring to be installed. The inner diameter of the sleeve for installing the inner ring should be slightly larger than the diameter of the main shaft, and the outer diameter of the sleeve for installing the outer ring should be slightly smaller than the bore diameter of the bearing housing. It is absolutely not allowed to hit the outer ring of the bearing when installing the inner ring of the bearing or the inner ring when installing the outer ring, so that the hammering force will be transmitted to the other ring through the rolling body and the raceway, resulting in damage to the raceway and the rolling body. If the fit of the inner and outer rings of the separable bearing is tight with the journal and seat hole, the end face of the sleeve must be in contact with the end face of the inner and outer rings at the same time, and the end face of the sleeve must be flat and perpendicular to the center line of the sleeve.

When using a hand hammer to hit the sleeve to install the bearing, on the one hand, the force on the bearing will not be stable, and on the other hand, an impact will be generated on the bearing. Therefore, unless the conditions are limited, this method is generally not recommended when installing precision bearings.

The pressure devices used in this installation method mainly include presses, presses, hydraulic clamps and hydraulic nuts. The characteristic of this method is that the bearing will not be directly hit, so the bearing is not easily damaged. However, when using this method, it must be ensured that the pressure line coincides with the axis of the bearing to prevent the bearing from tilting.

When the interference of the bearing fit is large by using the shrink fit method, it is difficult to install the bearing by using the pressure device method, and it is easy to damage the mating surface of the bearing. Therefore, if the inner ring of the bearing is heated and expanded, the bearing will be easier to install into the main shaft.

At present, the magnetic induction heater is often used to heat the inner ring of the bearing when the thermal charging method is adopted. The heating temperature of the bearing should not exceed 120C. The specific heating temperature depends on the size and interference of the bearing.

Since the size of the outer ring of the bearing also becomes wider during the heating process of the bearing, it is easy to produce a gap with the shaft shoulder in the axial direction after the bearing is cooled, and the bearing is in an interference fit state with the main shaft after the bearing is cooled. When the bearing is cooled, use nuts or other suitable methods to eliminate the axial clearance between the bearing and the shaft shoulder.

Inject pressure oil between the mating surfaces. When there is interference between the shaft and the bearing, the friction between the mating surfaces is very large, and when the interference is large, the mating surface may be damaged. If the pressure oil is injected between the mating surfaces, the two mating parts are slightly deformed, and the pressure oil seeps into the mating surfaces to form a layer of lubricating oil film, which can greatly reduce the friction between the mating surfaces. In this way, the two matching parts can be relatively slid with less force. This method is not only suitable for the installation of conical surface fittings, but also suitable for the assembly and disassembly of cylindrical surface fittings.