1. Assembly of sliding bearings

Sliding bearings are a type of bearing with sliding friction properties. They are characterized by stable operation, reliability, low noise, and the ability to withstand heavy loads and large impact loads. According to different structural forms, they can be divided into integral, split, and tile types.

(1) Assembly of integral sliding bearings

Integral sliding bearings are commonly known as sleeves. They are also a simple form of sliding bearings. They are mainly assembled by pressing and hammering. In special occasions, they are assembled by hot-fitting. Most sleeves are made of copper or cast iron. Be careful when assembling. They can be assembled by hammering with a wooden hammer or a hammer with a wooden block. When the interference dimension tolerance is large, press them in with a press. Whether knocking in or pressing in, tilting must be prevented. After assembly, the oil groove and oil hole should be in the required position.

Bearings that are deformed after assembly should have their inner holes trimmed. Smaller ones can be cut with a reamer, and larger ones can be scraped. At the same time, pay attention to controlling the clearance with the shaft within the tolerance range. To prevent the sleeve from rotating during operation, positioning pins or saddle screws are installed on the contact surface between the sleeve and the housing. Due to the different hardness of the housing and sleeve materials, it is easy for the drill to deviate to the soft material side when drilling. The solution is: first, use a sample punch to punch the hole on the hard material side before drilling, and second, use a short drill bit to increase the rigidity of the drill bit when drilling.

(2) Assembly of split bearings

Split bearings, also known as split bearings, have the characteristics of simple structure and convenient adjustment and disassembly. Two bearings are mounted on the bearing shells, and a gasket is used to adjust a reasonable gap at the joint.

① Assembly of bearing shells and bearing bodies

The upper and lower bearing shells must have good contact with the inner hole of the bearing body. If they do not meet the requirements, the bearing shell back should be scraped based on the inner hole of the thick-walled bearing shell. At the same time, the steps at both ends of the bearing shell should be close to the two ends of the bearing body. For thin-walled shells, it is sufficient to make the center plane of the bearing shell higher than the center plane of the bearing body by about 0.1mm, and no scraping is required.

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

③ Scraping of bearing shells

Split bearing shells are generally used with matching shaft grinding points. Generally, the bearing shells are scraped off first, and then the bearing shells are scraped on. In order to improve efficiency, the bearing shells and covers can be installed when scraping off the bearing shells. When the contact point of the lower bearing shell basically meets the requirements, the upper bearing shell and the upper cover are pressed tightly, and the contact point of the lower bearing shell is further corrected when scraping the upper bearing shell. The 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 rotate easily without obvious gaps, and the contact point meets the requirements, and the scraping is completed.

④ Measurement of bearing clearance

The size of the bearing clearance can be adjusted by the gasket at the center dividing surface, or it can be obtained by directly scraping the bearing shell. The bearing clearance is usually measured by the lead pressing method. Take several pieces of lead wire with a diameter larger than the bearing clearance, place them on the journal and the center plane, then tighten the nut to compress the center plane, unscrew the nut, remove the bearing cover, carefully remove the compressed lead wire, and measure the thickness of each piece with a micrometer. The bearing clearance can be known based on the average thickness of the lead wire. Generally, the bearing clearance should be 1.5‰-2.5‰ (mm) of the shaft diameter. A smaller clearance value is used when the diameter is larger. For example, the bearing clearance of a 60mm shaft diameter should be between 0.09-0.15mm.

2. Rolling bearing assembly

Rolling bearings have the advantages of low friction, small axial size, easy replacement, and simple maintenance.

(1) Technical requirements for assembly

① The end face of the rolling bearing marked with a code should be installed in a visible direction for easy checking during replacement.

② The arc radius at the step of the journal or housing hole should be smaller than the arc radius at the corresponding position on the bearing.

③ After the bearing is assembled on the shaft and in the housing hole, there should be no skew.

④ Among the two coaxial bearings, one must move with the shaft when the shaft expands thermally.

⑤ When assembling rolling bearings, dirt must be strictly prevented from entering the bearings.

⑥ The assembled bearings must be flexible, low-noise, and the operating temperature should generally not exceed 65°C.

(2) Assembly method

When assembling bearings, the basic requirement is to make the added axial force act directly on the end face of the bearing ring (when installed on the shaft, the added axial force should act directly on the inner ring, and when installed on the hole, the added force should act directly on the outer ring). Try not to affect the rolling element. The assembly methods include hammering, press assembly, hot assembly, and frozen assembly.

① Hammering method

Use a hammer to pad a copper rod and some relatively soft materials before hammering. Be careful not to let foreign matter such as copper powder fall into the bearing raceway. Do not directly hit the inner and outer rings of the bearing with a hammer or punch to avoid affecting the matching accuracy of the bearing or causing bearing damage.

② Screw press or hydraulic press assembly method

For bearings with large interference tolerance, screw press or hydraulic press can be used for assembly. Before pressing, the shaft and bearing should be laid flat and a little lubricating oil should be applied. The pressing speed should not be too fast. After the bearing is in place, the pressure should be removed quickly to prevent damage to the bearing or shaft.

③ Hot-fitting method

The hot-fitting method is to heat the bearing in oil to 80℃-100℃, expand the inner hole of the bearing, and then put it on the shaft to prevent damage to the shaft and bearing. The hot-fitting method is not suitable for bearings with dust covers and sealing rings that are filled with grease inside.

(3) The clearance of tapered roller bearings is adjusted after assembly. The main methods are adjustment with gaskets, screws, nuts, etc.

(4) When assembling thrust ball bearings, the tightening ring and loose ring should be distinguished first. The inner diameter of the tightening ring is slightly smaller. The assembled tightening ring and the shaft remain relatively still during operation. It always rests on the step or end face of the shaft, otherwise the bearing will lose its rolling effect and wear faster.

3. Instructions for use of rolling bearings

When installing bearings, the force should be evenly applied and cannot be hammered directly. For example, if the interference fit is large, the bearing should be heated in an air heating furnace or oil furnace with automatic temperature control, and the heating temperature should be strictly controlled below 120°.

Bearings equipped with nylon cages can work continuously and stably at -40°-120° for a long time. They should not work for more than 4 hours at 150°, and the short-term temperature peak can reach 180°.

The warehouse where bearings are stored should be clean and dry. They are not allowed to be stored in the same warehouse as chemical products. The relative humidity should not exceed 65%, and the bearings are not allowed to be stored on the ground.

(1) Installation and use of deep groove ball bearings

When installing bearings, the force should be evenly applied and cannot be hammered directly. For example, if the interference fit is large, the bearing should be heated in an air heating furnace or oil furnace with automatic temperature control, and the heating temperature should be strictly controlled below 120°.

Bearings equipped with nylon cages can work continuously and stably at -40°-120° for a long time, should not work for more than 4 hours at 150°, and the short-term temperature peak should not exceed 180°.

The warehouse where the bearings are stored should be clean and dry. They should not be stored in the same warehouse as chemical products. The relative humidity should not exceed 65%, and the bearings should not be stored on the ground.

The inventory bearings should be re-cleaned every year and rust-proofed.

(2) Installation and use of angular contact ball bearings

When installing the bearings, the force should be evenly distributed and should not be hammered directly. For example, if the interference fit is large, the bearing should be heated in an air heating furnace or oil furnace with automatic temperature control, and the heating temperature should be strictly controlled below 100°.

Bearings equipped with nylon cages can work stably and continuously for a long time at -40°-120°. They should not work for more than 4 hours at 150°. The short-term temperature peak can reach 180°.

The warehouse where bearings are stored should be clean and dry. They are not allowed to be stored in the same warehouse as chemical products. The relative humidity should not exceed 65%, and bearings are not allowed to be stored on the ground.

(3) Installation and use of spherical roller bearings

Users should select the appropriate fit and axial clearance of the bearing according to the use requirements. Please check the bearing code after unpacking.

Before installing the bearing, if grease is required in the bearing, the grease must be clean and appropriate.

During installation, it is advisable not to directly hammer the inner and outer ring end faces and rollers to avoid cracking the inner ring or the middle and small ribs. Usually, users should put the bearing in mineral oil and heat it to 90°-100° and immediately install it on the main shaft. Avoid using local spraying method for bearings. When it is difficult to "hot install", users should also use special sleeves for installation.

The bearings should be well sealed and lubricated during use, and the oil should not be cut off.

The bearing warehouse should be clean and dry, free of environmental pollution, and the bearings should not be stacked on the ground and the packaging should not be damaged. Bearings that have been in stock for more than 1 year must be re-cleaned and re-oiled.

(4) Installation and use of thrust spherical roller bearings

When installing the bearings, the bearing oil seal should be cleaned and then coated with clean lubricating oil.

When installing the bearings, the force should be even and not hammered. If the interference fit is large, the bearings should be placed in mineral oil and heated to 90°-100° before installation.

The warehouse where the bearings are stored should be clean and the relative humidity should not exceed 65%.

The inventory bearings should be re-cleaned and re-oiled once every year, and the oil seal packaging should be kept in good condition.

When using the bearings, they should have good sealing and dustproof devices, and the working condition should be checked frequently.

(5) Installation and use of cylindrical roller bearings

This bearing is a split type, and the user can adjust the clearance according to the needs during installation.

Before using, the bearings should be cleaned with gasoline or kerosene and kept well lubricated.

When installing the bearings, the bearings should be pressed into the components and knocking is strictly prohibited.

The storage area of the bearings should be clean and ventilated to avoid moisture. Bearings that need to be stored for a long time should be regularly rust-proofed.

(6) Installation and use of thrust ball bearings

When installing the bearings, the bearing seals should be removed, cleaned and then coated with clean lubricating oil.

When installing the bearings, the force should be evenly applied and hammering is not allowed. If the interference fit is large, the bearings should be placed in mineral oil and heated to 90°-100° before installation.

The warehouse where the bearings are stored should be clean and the relative humidity should not exceed 65%.

The inventory bearings should be re-cleaned and oiled once every year, and the oil seal packaging should be kept in good condition.

When using the bearings, there should be good sealing and dustproof devices, and the working condition should be checked frequently.