Discussion on some skills and precautions of bearing installation (interference assembly) (bearing heater)
Tips and precautions for shaft bearing installation (interference assembly)
Whether the bearing is installed correctly or not directly affects the accuracy, service life and performance of the bearing.
For the installation of bearings or large-size bearings with large interference, in order to facilitate the installation, the principle of heat expansion and cold contraction can be used to freeze the bearings in the industrial refrigerator, and then install them with copper bars, sleeves and hammers.It is suggested to choose a bearing refrigeration industrial freezer of – 100 ℃ ~ – 30 ℃.
Generally, the fit between bearing and shaft is transition fit, and the fit between seat ring and bearing seat hole is clearance fit. The middle ring of the two-way bearing shall be fixed on the shaft to prevent rotation relative to the shaft. Generally, the installation method of the bearing is that the shaft rotates mostly, so the fit between the inner ring and the shaft is over win fit, and the fit between the outer ring and the bearing chamber is clearance fit.
When installing the bearing, first fix the dial indicator on the end face of the case, so that the contact of the indicator can rotate the bearing on the raceway of the bearing ring, and observe the pointer of the dial indicator while rotating. If the pointer is skewed, it means that the axis ring and the axis center line are not vertical. If the case hole is deep, it can also be inspected with extended micrometer. This is a good way to check the perpendicularity of the shaft circle and the shaft centerline.
If the bearing is installed reversely, not only the bearing does not work normally, but also the mating surfaces will be severely worn. As the difference between the shaft ring and the seat ring is not obvious, special care should be taken during the assembly to avoid reverse installation. When the installation is correct, its seat ring can automatically adapt to the rolling of the rolling body, and ensure that the rolling body is located in the upper and lower ring raceways. In addition, a clearance of 0.2-0.5mm shall be left between the bearing race and the bearing race hole to compensate the error caused by the processing and installation of the parts. When the center of the bearing race is displaced during the operation, the clearance can ensure its automatic adjustment, avoid contact and friction, and make it run normally. Otherwise, the bearing will be severely damaged.
Precautions during installation:
- For IKO imported bearing rings with clearance fit, it is recommended to apply a thin layer of anti creep corrosion agent on the fitting surface to prevent friction corrosion between the mating surfaces.
- The force exerted on the bearing during installation must not be transferred from one bearing ring to another through the rolling element, otherwise the raceway may be damaged. However, under no circumstances should the bearing ring, cage, rolling element or seal be knocked directly.
- Install eccentric sleeve. First, put the eccentric sleeve on the eccentric step of the bearing inner sleeve, and tighten it by hand in the direction of rotation of the shaft. Then, insert or counter the small iron bar into the counterbore of the eccentric sleeve. Tap the small iron bar with the hammer in the direction of rotation of the shaft to make the eccentric sleeve firmly installed. Finally, lock the hexagon socket screw on the eccentric sleeve.
- Do not tighten the bolts to fix the bearing seat. Make sure that the bearing sleeve can rotate in the bearing seat. Then fasten the bolts of bearing seat. Also install the bearing and seat at the other end of the same shaft, rotate the shaft several times, and let the bearing itself automatically align the position.
- Apply lubricating oil on the mating surface of bearing seat and bearing, and install IKO inlet bearing into bearing seat. Then the assembled bearing and bearing seat are sleeved on the shaft and pushed to the required position for installation.