There is a lot of knowledge in bearing assembly, and the bearing factory will teach you how to assemble bearings

Assembly of sliding bearings:

Sliding bearing is a type of bearing with sliding friction properties, characterized by smooth operation, reliability, low noise, and the ability to withstand heavy loads and large impact loads. It can be divided into integral, split, and tile types according to different structural forms.

(1) Assembly of integral sliding bearings

Integrated sliding bearings, commonly known as shaft sleeves, are also the simplest form of sliding bearings. They are mainly assembled by pressing and hammering, and in special cases, hot fitting is used. Most shaft sleeves are made of copper or cast iron, and assembly should be careful. Wooden hammers or hammers can be used to hit wooden blocks during assembly. When the interference size tolerance is large, a press is used to press in. Regardless of whether it is knocked in or pressed in, it is necessary to prevent tilting. After assembly, the oil tank and oil hole should be in the required position.

Bearings that deform after assembly should have their inner holes repaired. Smaller sizes can be machined with a reamer, while larger sizes can be scraped. At the same time, pay attention to controlling the fit clearance with the shaft within the tolerance range. To prevent the shaft sleeve from rotating during operation, the contact surface between the shaft sleeve and the box is equipped with locating pins or saddle screws. Due to the different hardness of the casing and shaft sleeve materials, it is easy for the drill bit to lean towards the soft material side when drilling. The solution is to use a sample to punch the hole against the hard material side before drilling, and to use a short drill bit to increase the rigidity of the drill bit during drilling.

(2) Assembly of Split Bearing

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

① Assembly of bearing shells and bearing bodies

The contact between the upper and lower bearing shells and the inner hole of the bearing must be good. If it does not meet the requirements, the inner hole of the thick walled bearing shell should be used as the reference, and the back of the bearing shell should be scraped. At the same time, the steps at both ends of the bearing shell should be close to the two ends of the bearing body. Thin walled tiles only need to be raised by about 0.1mm above the midpoint of the bearing body, without the need for scraping.

② The bearing shells are installed in the bearing body

No displacement is allowed in both radial and axial directions, and usually the steps at both ends of the bearing are used to stop or locate the positioning pin.

③ Scraping of bearing shells

Generally, split type bearing shells use matching grinding points. Generally, the bearing shells are scraped off first, and then the upper bearing shells are scraped on. In order to improve efficiency, the bearing shells and covers may not 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 cover are pressed tightly. When scraping off the upper bearing shell, the contact point of the lower bearing shell is further corrected. The tightness of the shaft during scraping can be adjusted by changing the thickness of the gasket as the number of scrapings increases. After the bearing cover is tightened, the shaft can easily rotate without obvious clearance, and the contact point meets the requirements, which is completed by scraping.

④ Measurement of bearing clearance

The size of the bearing clearance can be adjusted by the gasket at the split surface or by directly scraping the bearing shells. The measurement of bearing clearance is usually carried out using the lead pressing method. Several pieces of lead wire with a diameter larger than the bearing clearance are taken and placed on the shaft neck and the split surface. Then, the nut is tightened to press the split surface tightly, and the nut is unscrewed. The bearing cover is removed, and the flattened lead wire is carefully taken out. The thickness of each piece is measured using a micrometer, and the bearing clearance can be determined based on the average thickness of the lead wire. The clearance of general bearings should be 1.5 ‰ -2.5 ‰ (mm) of the shaft diameter, and the smaller clearance value should be taken for larger diameters. The clearance between bearings with a shaft diameter of 60mm should be between 0.09 and 0.15mm.

Assembly of rolling bearings:

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

(1) Technical requirements for assembly

① The end faces of rolling bearings marked with codes should be installed in a visible direction for easy alignment during replacement.

② The radius of the arc at the step of the shaft neck or shell hole should be smaller than the radius of the arc at the corresponding position on the bearing.

③ After assembling the bearings on the shaft and in the housing holes, there should be no tilting phenomenon.

④ In two coaxial bearings, one must experience shaft movement as the shaft expands.

⑤ When assembling rolling bearings, it is necessary to strictly prevent dirt from entering the bearing.

⑥ The assembled bearings must operate flexibly, have low noise, and generally should not exceed a working temperature of 65 ℃

(2) Assembly method

When assembling bearings, the most basic requirement is to apply axial force directly to the end face of the bearing ring (when installed on the shaft, apply axial force directly to the inner ring, and when installed on the hole, apply force directly to the outer ring). Try not to affect the rolling element as much as possible. The assembly methods include hammering method, press assembly method, hot assembly method, frozen assembly method, etc.

① Hammering method

The method of using a hammer to pad a copper rod and some relatively soft materials before hammering is to be careful not to let foreign objects 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 fitting accuracy of the bearing or causing damage to the bearing.

② Assembly method of screw press or hydraulic press

For bearings with large interference tolerances, they can be assembled using a screw press or hydraulic press. Before pressing, the shaft and bearings should be leveled and coated with a little lubricating oil. The pressing speed should not be too fast. After the bearings are in place, the pressure should be quickly removed to prevent damage to the bearings or shafts.

③ Hot charging method

The hot fitting method is to heat the bearing in oil to 80 ℃ -100 ℃, so that the inner hole of the bearing expands and fits onto the shaft, which can prevent damage to the shaft and bearing. For bearings with dust covers and sealing rings, the hot fitting method is not suitable for bearings that are already filled with lubricating grease inside.

(3) The clearance of tapered roller bearing is adjusted after assembly. The main methods are shim adjustment, screw adjustment, nut adjustment, etc.

(4) When assembling thrust ball bearings, the first step is to distinguish between the tight ring and the loose ring. The inner diameter of the tight ring is slightly smaller, and the assembled tight ring and shaft remain relatively stationary during operation. It always leans against the step or hole end face of the shaft, otherwise the bearing will lose its rolling effect and accelerate wear.