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The so-called fixed NSK bearing is an annular part of a thrust rolling bearing with one or several raceways. Fixed end bearings use radial bearings that can withstand combined (radial and axial) loads. These bearings include deep groove ball bearings, double row or paired single row angular contact ball bearings, self-aligning ball bearings, spherical roller bearings, matched tapered roller bearings, NUP cylindrical roller bearings or NJ cylindrical roller bearings with HJ angle rings. In addition, the bearing configuration at the fixed end can include a combination of two bearings:
1. Radial bearings that can only bear radial load, such as cylindrical roller bearings with one ring and no flange.
2. Provide axially positioned bearings, such as deep groove ball bearings, four point contact ball bearings or two-way thrust bearings.
The bearing for axial positioning must not be positioned radially. It is usually installed on the bearing seat with small radial clearance.
First, use a bearing that only bears radial load and allows axial displacement to occur inside the bearing. These bearings include carb ring roller bearing, needle roller bearing and one ring cylindrical roller bearing without retaining edge. Another method is to use a radial bearing with a smaller radial clearance when installed on the bearing seat, so that the outer ring can move freely axially.
1. Before installing the NTN bearing on the shaft, first pull out the fixing pin fixing the bearing sleeve, polish the surface of the journal smooth and clean, and apply oil at the journal for rust prevention and lubrication (the bearing is allowed to rotate slightly on the shaft).
2. Apply lubricating oil on the mating surface of the bearing seat and the bearing, and install the double row tapered roller bearing into the bearing seat. Then sleeve the assembled bearing and bearing seat on the shaft and push it to the required position for installation.
3. Do not tighten the bolts for fixing the bearing seat, but let the bearing sleeve rotate in the bearing seat. Similarly, install the bearing and seat at the other end of the same shaft, rotate the shaft for several turns, and make the fixed bearing automatically align its position. Then fasten the bearing seat bolts.
4. Install eccentric sleeve. First put the eccentric sleeve on the eccentric step of the bearing inner sleeve and tighten it by hand along the rotation direction of the shaft. Then insert or counter the small iron rod into the counterbore on the eccentric sleeve. Knock the small iron rod along the rotation direction of the shaft with a hand hammer to make the eccentric sleeve firmly installed, and then lock the Allen screw on the eccentric sleeve.
In the two-way limit support, the inner ring of the bearing is on the shaft and the outer ring in the bearing seat hole must be fastened in two-way axial direction. In the unidirectional limit support, it is necessary to apply unidirectional axial fastening to the inner and outer rings in the opposite direction of force transmission.
If a non split bearing is selected as the swimming support, only the inner ring needs to be axially fastened on the shaft in two directions, and the outer ring moves axially relative to the seat hole. When the centripetal bearing with separable inner and outer rings is selected as the swimming support, the inner and outer rings need to be axially fastened on the shaft and the seat hole in two directions, and the inner and outer rings of the bearing move axially relative to each other.
The axial positioning of fag bearing is usually the shoulder positioning of the inner ring and the shoulder positioning of the bearing seat hole of the outer ring.
In order to ensure the positioning effect of the shaft shoulder and retaining shoulder, the shaft shoulder and retaining shoulder shall be close to the end faces of the inner and outer rings of the bearing. The height of shaft shoulder and retaining shoulder shall also be selected according to the specification. The fixing method of bearing inner and outer rings shall correspond to the size of force transfer.
When installing the bearing inner ring with interference fit, one side of the inner ring is usually against the shoulder on the shaft, and the other side is generally fixed with a lock nut (KMT or KMTA Series). Bearings with tapered holes are mounted directly on tapered journals and are usually fixed to the shaft with lock nuts.
It is convenient to use spacer sleeves or spacer rings between ina bearing rings or between bearing rings and adjacent parts to replace the integral shaft shoulder or bearing seat shoulder. In these cases, dimensional and shape tolerances also apply to the relevant parts.
Another method of bearing axial positioning is to use stepped shaft sleeve. These bushings are particularly suitable for precision bearing configurations, with less runout and higher accuracy than threaded lock nuts. Stepped shaft sleeve is usually used for ultra-high speed spindle. For this kind of spindle, the traditional locking device can not provide it with sufficient accuracy.
When installing the bearing outer ring with interference fit, one side of the outer ring is usually against the shoulder on the bearing seat, and the other side is fixed with a fixed end cover. The fixed end cap and its fixing screws have a negative impact on the shape and performance of the bearing in some cases.
If the wall thickness between the bearing pedestal and the screw hole is too small, or the screw is tightened too tightly, the outer race may be deformed. Light ISO size series 19 series are more susceptible to such damage than 10 series or heavier series.