Bearing installation and inspection method

20-08-2020

In the process of bearing installation, one principle must be grasped, that is, the installation force or torque can only be transmitted through corresponding rings.

Press fit

When the inner ring of the bearing is tightly matched with the shaft, and the outer ring and the bearing seat hole are loosely matched, the bearing can be pressed onto the shaft with a press, and then the shaft and the bearing are installed into the bearing seat hole together. When pressing, a soft metal assembly sleeve (copper or soft steel) is padded on the end face of the bearing inner ring.

The outer ring of the bearing is tightly matched with the bearing seat hole. When the inner ring and the shaft are in a loose fit, the bearing can be pressed into the bearing housing hole first. At this time, the outer diameter of the assembly sleeve should be slightly smaller than the diameter of the seat hole.

If the bearing ring is tightly fitted with the shaft and seat hole, the inner ring and outer ring of the installation chamber should be pressed into the shaft and seat hole at the same time. The structure of the assembly sleeve should be able to tighten the end faces of the bearing inner ring and outer ring at the same time.

By heating the bearing or bearing seat, the tight fit is transformed into a loose fit by thermal expansion. It is a common and labor-saving installation method. This method is suitable for the installation of bearings with large interference. Before hot installation, put the bearing or separable bearing ring into the oil tank and heat it evenly for 80-100 ℃. Then, take it out of the oil and install it on the shaft as soon as possible. In order to prevent the inner ring end face and the shaft shoulder from not tight after cooling, the bearing can be tightened axially after cooling. When the outer ring of the bearing is tightly matched with the bearing seat made of light metal, the hot mounting method of heating the bearing seat can avoid the scuffing of the mating surface.

When heating the bearing with oil tank, there should be a grid at a certain distance from the bottom of the box. The bearing should not be placed on the bottom of the box to prevent impurities from entering the bearing or heating unevenly. There must be a thermometer in the oil tank. The oil temperature should not exceed 100 ℃ to prevent tempering effect and reduce the hardness of the ring.

Installation of thrust bearing

Generally, the fit between the circumference of thrust bearing and the shaft is transition fit, and the fit between race and bearing seat hole is clearance fit. Therefore, the bearing is easy to install. The middle shaft spring of bidirectional thrust bearing should be fixed on the shaft to prevent rotation relative to the shaft.

The installation method of bearing is usually shaft rotation, so the fit of inner ring and shaft is interference fit, and the fit of bearing outer ring and bearing chamber is clearance fit.

Bearing operation inspection

After the bearing is installed, it should be checked to ensure that the bearing is installed in place, rotating flexibly and without clamping stagnation. If the bearing is not properly installed, the bearing temperature will rise rapidly and be damaged, and even serious accidents such as bearing seizure and fracture will occur.

Use and storage of bearings

(1) When the bearing is used, keep the surrounding environment clean and do not stick with sweat and dirt. It is required to be used by personnel familiar with the bearing, especially to be careful of damage, indentation and under damage. In order to ensure the service performance of the bearing, the bearing should be regularly maintained, maintained and overhauled according to the operation standard of the equipment, including monitoring the operation status, adding lubricant, and regular disassembly and inspection.

(2) Bearings shall not be stored directly on the ground (more than 30cm above the ground) to avoid direct light and cold walls. In order to prevent rusting, the bearing should be kept in the environment with temperature about 20 ℃ and humidity below 65%. If the bearing is placed in acid air, it is easy to rust and change color. The bearing, shaft and shell should be wiped with gloves and kapok. Garbage entering the bearing and the matching part is the cause of abnormality, so attention should be paid.


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