Installation of bearings

Update: 28-12-2019

The quality of the bearing installation will affect the […]

The quality of the bearing installation will affect the accuracy, life and performance of the bearing. Therefore, please fully study the bearing installation, that is, install the bearing according to the operating standards including the following items.

1. Cleaning bearings and related parts

Because the bearings are rust-proofed and packaged, do not open the package until just before installation. In addition, the anti-rust oil coated on the bearing has good lubricating performance. For general-purpose bearings or grease-filled bearings, it can be used without cleaning. However, for instrument bearings or bearings used for high-speed rotation, the anti-rust oil should be washed away with clean cleaning oil. At this time, the bearings are easy to rust and cannot be left for a long time. For grease-lubricated bearings and oil seals or dust covers on both sides, seal rings need not be cleaned before installation.

2.Check the size and finishing of related parts

Clean the bearing and housing to make sure there are no nicks or burrs left by machining. Absolutely no abrasive (SiC, Al2O3, etc.) molding sand, chips, etc. are required in the shell.

Secondly, check whether the size, shape and processing quality of the shaft and the shell are consistent with the drawings.
 3.1 Press fit

The inner ring of the bearing and the shaft are tightly fitted. When the outer ring and the bearing seat hole are loosely fitted, the bearing can be press-fitted on the shaft with a press, and then the shaft and the bearing are inserted into the bearing seat hole. On the end face of the bearing inner ring, a soft metal material mounting sleeve (copper or soft steel) is cushioned. The inner diameter of the mounting sleeve should be slightly larger than the diameter of the journal and the outer diameter should be slightly smaller than the flange of the inner ring of the bearing to avoid Press on the cage. The outer ring of the bearing fits tightly with the bearing seat hole. When the inner ring and the shaft are loosely fitted, the bearing can be pressed into the bearing seat hole first. At this time, the outer diameter of the mounting sleeve should be slightly smaller than the diameter of the seat hole. If the bearing ring is tightly fitted with the shaft and the seat hole, the inner and outer rings must be pressed into the shaft and the seat hole at the same time. The structure of the mounting sleeve should be able to tighten the end faces of the bearing inner ring and outer ring at the same time.

3.2 Heating fit

By heating the bearing or bearing seat, the thermal expansion is used to transform the tight fit into a loose fit installation method. Is a common and labor-saving installation method. This method is suitable for the installation of bearings with a large amount of interference. Before the hot-loading, the bearing or separable bearing ring is put into the oil tank and heated evenly at 80-100 ° C, and then removed from the oil and installed on the shaft as soon as possible. Prevent the inner ring end face from abutting tightly with the shoulder after cooling, and axially tighten the bearing after cooling. When the bearing outer ring is tightly matched with a light metal bearing seat, a hot mounting method using a heated bearing seat can be used to prevent the mating surface from being scratched. When heating the bearing with the fuel tank, there should be a grid at a certain distance from the bottom of the tank, or the bearing should be hung with a hook. The bearing cannot be placed on the bottom of the tank to prevent sinking impurities from entering the bearing or uneven heating. There must be a thermometer in the tank. Strictly control the oil temperature to not exceed 100 ℃ to prevent the tempering effect and reduce the hardness of the ferrule.

3.3 Installation of tapered bore bearings

The tapered bore bearing can be directly mounted on the tapered journal, or the tapered surface of the adapter sleeve and the withdrawal sleeve. The degree of fit can be measured by the reduction of the radial clearance of the bearing. Therefore, it should be installed before installation. Measure the radial clearance of the bearing. During the installation process, the clearance should be measured frequently to achieve the required clearance reduction. Generally, the installation is performed with a lock nut or a heating installation method.

3.4 Installation of thrust bearings

The overall fit of the thrust bearing and the shaft is generally a transition fit. The fit of the seat ring and the bearing seat hole is generally a clearance fit. Therefore, this type of bearing is easy to install. The center shaft spring of the two-way thrust bearing should be fixed on the shaft to prevent relative Turn on the shaft. The bearing installation method is generally the case where the shaft rotates, so the fit between the inner ring and the shaft is an over-win fit, and the fit between the bearing outer ring and the bearing chamber is a clearance fit.

3.5 Inspection after bearing installation

3.6 Adding lubricant