Bearing and shaft assembly technology method

Bearings are components used to support and also support parts that rotate on the shaft. The types of bearings are divided according to friction properties: there are sliding bearings and rolling bearings; according to the direction of the load: centripetal bearings, push bearings, centripetal thrust Bearings, etc.

 

Sliding bearing is a kind of sliding friction bearing, which is characterized by smooth operation, reliable noise, and can withstand heavy loads and large impact loads. It can be divided into integral type, split type and pad type according to the structure.

 

(1) Assembly of integral sliding bearing

 

Integral sliding bearings, commonly known as bushings, are also the simplest form of sliding bearings. They are mainly assembled by press-in and hammering, and hot-packing methods are used in special occasions. Most bushings are made of copper or cast iron. Care should be taken when assembling with wooden hammers or hammer pads. When the tolerance of the interference dimension is large, press it in. 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 during operation, the contact surface of the shaft sleeve and the box body is equipped 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 bearings

 

 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 a gasket at the joint.

 

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 bush is not used as a reference, scrape the back of the bearing bush, and the steps at both ends of the bearing bush should be close to the two ends of the bearing body. The thin-walled tile only needs to make the mid-segment surface of the bearing pad higher than the mid-segment surface of the bearing body by about 0.1 mm, and does not need to be scraped.

 

②The bearing bush is installed in the bearing body, no displacement is allowed in the radial direction or the axial direction. Usually, the steps at both ends of the bearing bush are used to stop positioning or positioning pin positioning.

 

③Shaft matching

 

The split bearing usually uses the matching shaft grinding 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. After 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 gap can be adjusted by the spacer at the mid-parting surface, 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 measure the thickness with a micrometer for each section. Based on 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. When the diameter is larger, the smaller clearance value is adopted. If the shaft diameter is 60mm, the bearing clearance should be between 0.09-0.15mm.