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Installation of cylindrical bore bearings

by:JNSN     2021-11-05
Press-in method with a press

The press-in method is widely used in small bearings. As shown in Figure 1, press the cushion block against the inner ring and use a press to slowly press it until the end face of the inner ring is close to the shaft shoulder. Mounting the inner ring with the outer ring against the spacer will cause indentation or crushing on the raceway, so it is absolutely forbidden.

Furthermore, during operation, oil should be applied to the mating surface in advance. If you must use a hammer to install, you must put a block on the inner ring. This practice has repeatedly caused bearing damage, so it is limited to the case of small interference and cannot be used for large or medium and large bearings.

Non-separable bearings, such as deep groove ball bearings, require interference installation of the inner and outer rings. As shown in Figure 2, use screw or oil pressure to press in the inner and outer rings at the same time using spacers. The outer ring of self-aligning ball bearing is easy to tilt, even if it is not an interference fit, it is best to install it with a pad.

Separable bearings, such as cylindrical roller bearings and tapered roller bearings, can be installed on the shaft and the bearing seat with the inner and outer rings respectively. When combining the separately installed inner ring and outer ring, the key is to close them firmly to prevent the center of the two from deviating, and pressing in will cause scratches on the rolling surface.

The method of hot mounting

Large bearings require a lot of force when pressed in, so it is difficult to work. Therefore, the hot mounting method is widely used: heating the bearing in oil to expand it, and then mounting it on the shaft. Using this method, there will be no improper force during installation and work time can be shortened.

The heating temperature of the bearing is determined by referring to Figure 3 based on the bearing size and the required interference. The precautions related to the hot loading operation are as follows.

(a) Bearing heating should not exceed 120゚C.

(b) In order to prevent the bearing from touching the bottom of the oil groove, the bearing should be placed on a metal grid or lifted.

(c) In order to prevent the difficulty of installation due to the decrease in the temperature of the inner ring during operation, the temperature should be 20°C-30°C higher than the required temperature when heating the bearing.

(d) After installation, the bearing cools down and the width direction shrinks, so use a shaft nut or other suitable method to lock it to prevent a gap between the inner ring and the bearing shoulder.

NSK induction heating device

In addition to heating with oil, NSK induction heating devices using the principle of electromagnetic induction are also widely used.

NSK induction heating device, built-in excitation coil, after energization, due to electromagnetic induction, the current is transmitted to the heating body (bearing), and heat is generated by the resistance of the bearing itself. Therefore, it can be heated uniformly in a short time without using fire or oil. The hot-loading operation of the bearing is efficient and clean.

In occasions with frequent assembly and disassembly, such as roller bearings and cylindrical roller bearings for railway vehicle axle boxes, NSK's special induction heating device can be used to install and disassemble the inner ring.

Installation of tapered bore bearings

Taper bore bearings directly fix the inner ring on the tapered shaft or install it on the cylindrical shaft with an adapter sleeve or a removal sleeve (as shown in Figure 4. Figure 5).

Large spherical roller bearings are mostly installed by hydraulic pressure. Figure 6 is an example of installation using hydraulic nuts to press into the adapter sleeve. Figure 7 is a method of installing oil holes on the adapter sleeve, while delivering high-pressure oil to the mating surface, while pressing the bolt into the adapter sleeve for installation.

Refer to Table 1 for the press-in amount of self-aligning bearing. Check the reduction in radial clearance and install it. Use a feeler gauge to measure the clearance, as shown in Figure 8. When measuring the clearances of the two rows at the same time, the values u200bu200bmust be basically equal.

As the size of the bearing increases, when it is installed on the shaft, due to the elliptical deformation of the outer ring due to its own weight, if the clearance is measured at the bottom of the deformed bearing, the measured number will be greater than the actual clearance. Use this error Radial clearance, installed according to the approximate standard in Table 1, will cause excessive interference or too small actual installation clearance. Therefore, as shown in Figure 9, the clearance is half the sum of the clearances a, b and the lowermost clearance c in the horizontal direction.

When the self-aligning ball bearing is installed on the shaft with an adapter sleeve, ensure that the outer ring can be flexibly adjusted and the clearance after installation cannot be too small.

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