Complete Guide on How to Assemble Plain Bearing

Plain bearing is a kind of sliding friction bearing. It has features of stable operation, low bearing noise, heavy load, and large impact load. Therefore according to different structural forms, it has three types of integral types, split type, and tile type, etc. 

(1) Assembly of integral plain bearing

Integral sliding bearings, commonly known as bushings, are also the simplest form of plain bearings. They are mainly assembled by press-in and hammering, and hot-packing methods are used on special occasions. Most bushings are made of copper or cast iron. Care should be taken when assembling with a wooden hammer or hammer pad wood block. When the tolerance of interference dimension is large, press it in with a press. Whether it is knocked or pressed, it must be prevented from tilting. After assembly, the oil groove and oil hole should be in the required position.

Bearings that are deformed after assembly should be trimmed with inner holes. Reamers can be used for smaller sizes and scrapers for larger sizes. At the same time, pay attention to control the clearance between the shaft and the shaft within the tolerance range. In order to prevent the shaft sleeve from rotating when working, the contact surface of the shaft sleeve and the box body is provided with a positioning pin or a riding screw. Due to the different hardness of the casing and the sleeve material, it is easy to deflect the drill bit to the soft material side. The solution: one is to punch the hard material with a sample before drilling, and the second is to use a short drill to increase the drill The rigidity of the drill when making holes.

(2) Assembly of split plain bearing

Split bearings, also known as split bearings, have the characteristics of simple structure and easy adjustment and disassembly. Two bearing pads are inserted on the bearing pads, and a reasonable gap is adjusted with gaskets at the joints.

①Assembly of bearing shell and bearing body

The contact between the upper and lower bearing pads and the hole in the bearing body must be good. If the hole in the bearing body of the thick-walled bearing is not used as a reference, scrape the back of the bearing pad, and the steps at both ends of the bearing pad should be close to the two ends of the bearing body. The thin-walled tile only needs to make the middle face of the bearing pad higher than the middle face of the bearing body by about 0.1 mm, and no scraping is necessary.

②The bearing bush is installed in the bearing body

No displacement is allowed in either the radial direction or the axial direction. Steps at both ends of the bearing pad are usually used to stop positioning or positioning pins.

③Shaft matching

The split bearing usually uses the matching shaft research point. Generally, the bearing is scraped first, and then the bearing is scraped. In order to improve efficiency, the bearing pad and cover are not installed when the bearing is scraped. The contact point of the lower bearing is basically when it meets the requirements, the upper bearing bush and the upper cover are pressed tightly, and when the upper bearing pad is scraped, the contact point of the lower bearing pad is further corrected.

The degree of tightness of the shaft during scraping can be adjusted by changing the thickness of the gasket as the number of scraping increases. When the bearing cover is tightened, the shaft can easily rotate without obvious gaps, and the contact point meets the requirements and the scraping is completed.

④Measurement of bearing clearance

The size of the bearing clearance can be adjusted by the spacer at the mid-face, or it can be obtained by directly scraping the bush. The bearing gap is usually measured by the lead pressing method. Take a few pieces of lead wire with a diameter larger than the bearing gap and place it on the journal and the middle split surface. Then tighten the nut to make the middle split surface tight. Then unscrew the nut and remove the bearing cover.

Take out the flattened lead wire, and take a section to make the micrometer measure the thickness. According to the average thickness of the lead wire, you can know the bearing clearance. Generally, the clearance of the bearing should be 1.5‰-2.5‰ (mm) of the shaft diameter, and the smaller the clearance value is, the larger the diameter is. If the shaft diameter is 60mm, the bearing clearance should be between 0.09-0.15mm.