Writer: Eric Bearing Limited
The so-called fixed 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 those with HJ angle rings NJ type cylindrical roller bearings.
In addition, the bearing arrangement at the fixed end can include a combination of two bearings:
1. Radial bearings that can only bear radial loads, such as cylindrical roller bearings with one ring without ribs.
2. Provide axial positioning bearings, such as deep groove ball bearings, four-point contact ball bearings or two-way thrust bearings.
Bearings used for axial positioning must never be used for radial positioning, and usually have a small radial clearance when installed on the bearing seat.
There are two ways to adapt to the thermal displacement of the floating bearing shaft. First, use a bearing that only bears radial loads and can allow axial displacement to occur inside the bearing. These bearings include: needle roller bearings and a cylindrical roller bearing with no ribs on the ring. Another method is to use a radial bearing with a small radial clearance when installed on the bearing seat so that the outer ring can move freely in the axial direction.
1. How to install INA fixed bearing?
(1) Before installing the bearing on the shaft, you must first unplug the fixing pin that fixes the bearing jacket, and at the same time, polish the surface of the journal smoothly, and apply oil to the journal to prevent rust and lubricate (allow the bearing to rotate slightly on the shaft ). INA HK2018-RS bearings online , pls click here :
(2) Apply lubricating oil on the bearing seat and the bearing mating surface, and install the double-row tapered roller bearing into the bearing seat. Then put the assembled bearing on the shaft together with the bearing seat and push it to the desired position for installation.
(3) Do not tighten the bolts that fix the bearing seat, but allow the bearing housing to rotate in the bearing seat. Also install the bearing and seat on the other end of the same shaft, rotate the shaft a few times, and let the fixed bearing automatically find its position. Then tighten the bearing seat bolts.
(4) Install eccentric sleeve. Put the eccentric sleeve on the eccentric step of the bearing inner sleeve first, and tighten it by hand in the direction of rotation of the shaft. Then insert the small iron rod into or against the counterbore on the eccentric sleeve. Hit the small iron rod with a hammer along the axis of rotation. Install the eccentric sleeve firmly, and finally tighten the hexagon socket screws on the eccentric sleeve.
In the two-way limit support, the inner ring of the INA bearing is on the shaft, and the outer ring in the bearing seat hole must be axially fastened in both directions. In the unidirectional limit support, it is necessary to apply unidirectional axial tightening to the inner and outer ring in the opposite direction of the force transmission.
If a non-separable bearing is used for the floating support, only the inner ring needs to be axially fastened to the shaft in both directions, and the outer ring moves freely in the axial direction relative to the seat hole. When the inner ring and the outer ring are separable centripetal When the bearing is used for floating support, both the inner and outer rings need to be axially fastened on the shaft and in the housing hole in both directions, and the inner and outer rings of the bearing move relative to each other.
The axial positioning of INA bearings is usually the shoulder positioning of the inner ring and the shoulder positioning of the bearing housing hole for the outer ring.
In order to ensure the positioning effect of the shaft shoulder and the retaining shoulder, the shaft shoulder and the retaining shoulder should be closely attached to the end surface of the bearing inner and outer ring. The height of the shaft shoulder and the retaining shoulder should also be selected according to the specification. The fixing method of the inner and outer rings of the bearing should correspond to the size of the transmission force.
2. Positioning method of fixed bearing
(1) Lock nut positioning method
When installing the bearing inner ring with interference fit, usually one side of the inner ring is against the shoulder on the shaft, and the other side is generally fixed with a lock nut. Bearings with tapered holes are directly installed on the tapered journal, usually fixed on the shaft with a lock nut.
(2) Spacer positioning method
It is convenient to use spacer sleeves or spacer rings between bearing rings or between bearing rings and adjacent parts instead of integral shaft shoulders or bearing seat shoulders. In these cases, dimensional and shape tolerances also apply to related parts.
(3) Stepped bushing positioning
Another method of bearing axial positioning is to use stepped bushings. These bushings are particularly suitable for precision bearing arrangements, and compared with threaded lock nuts, they have less runout and provide higher accuracy. Stepped bushings are usually used for ultra-high-speed spindles, for which traditional locking devices cannot provide sufficient accuracy.
(4) Fixed end cap positioning method
When the bearing outer ring is installed with interference fit, usually one side of the outer ring is against the shoulder on the bearing seat, and the other side is fixed with a fixed end cover. The fixed end cover 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 seat and the screw hole is too small, or the screw is tightened too tightly, the outer ring raceway may be deformed.