What Is the Assembly Knowledge of Sliding Bearings?

Sliding bearings are a kind of bearings with sliding friction properties. They are characterized by smooth 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 type, split type and tile type.

(1) Assembly of integral sliding bearings. Integral sliding bearings are commonly known as bushings. They are also the simplest form of sliding bearings. They are mainly assembled by press-in and hammering. In special occasions, the hot-fitting method is used. Most bushings are It is made of copper or cast iron. You should be careful when assembling it. You can assemble it by hitting it with a wooden hammer or hammer block. If the interference size tolerance is large, press it in with a press. Regardless of whether it is knocked or pressed in, tilting must be prevented. After assembly, the oil groove and oil hole should be in the required position.

If the bearing is deformed after assembly, the inner hole should be trimmed. If the bearing is smaller, it can be cut with a reamer, and if the bearing is larger, it can be scraped. At the same time, pay attention to controlling the matching gap with the shaft within the tolerance range. In order to prevent the shaft sleeve from rotating during operation, a positioning pin or a seam screw is installed on the contact surface between the shaft sleeve and the box. Due to the different hardness of the box and bushing materials, it is easy for the drill bit 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 drilling capacity. The rigidity of the drill bit when making holes.

(2) Assembly of split bearings Split bearings are also called split bearings. They have the characteristics of simple structure and easy adjustment and disassembly. Two bearing bushes are mounted on the bearing bush, and spacers are used at the joint to adjust to a reasonable gap.

① Assembling the bearing bush and the bearing body. The contact between the upper and lower bearing bushes and the bore in the bearing body must be good. If the requirements are not met, use the hole in the bearing body of the thick-walled bearing bush as a reference to scrape the back of the bearing bush. At the same time, the steps at both ends of the bearing bush should be close to the bearing. body ends. For thin-walled bushings, it is enough to make the middle plane of the bearing bush about 0.1mm higher than the middle plane of the bearing body, and there is no need to trim it.

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

③ The matching of the bearing bush. The split-type bearing bush generally uses a matching shaft grinding point. Generally, the bearing bush is scraped off first, and then the bearing bush is scraped on. In order to improve efficiency, the bearing bush and cover may not be installed when scraping off the bearing bush. Now When the contact point of the bearing bush basically meets the requirements, press the upper bearing bush and the upper cover tightly, and further correct the contact point of the lower bearing bush while scraping the upper bearing bush. When scraping, the tightness of the shaft can be adjusted by changing the thickness of the gasket as the number of scrapings increases. When the bearing cap 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 through the gasket at the center plane, or it can also be obtained by directly scraping the bearing bush. The lead pressing method is usually used to measure the bearing clearance. Take several pieces of lead wire with a diameter larger than the bearing clearance, place them on the journal and the middle plane, then tighten the nut to compress the middle plane, then unscrew the nut, remove the bearing cover, and carefully Take out the flattened lead wire and use a micrometer to measure the thickness of each section. The bearing clearance can be known based on the average thickness of the lead wire. Generally, the clearance of bearings should be 1.5‰-2.5‰ (mm) of the shaft diameter. When the diameter is larger, a smaller clearance value should be used. For example, if the shaft diameter is 60mm, the bearing clearance should be between 0.09-0.15mm.

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

(1) Technical requirements for assembly

① The end face of the rolling bearing marked with the code should be installed in a visible direction to facilitate verification 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 place on the bearing.

③ After the bearing is installed 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 thermally expands.

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

⑥ After assembly, the bearing must operate flexibly, have low noise, and the operating temperature should generally not exceed 65°C.

(2) Assembly method When assembling a bearing, the most basic requirement is to make the added axial force act directly on the end face of the ring of the installed bearing (when installed on the shaft, the added axial force must act directly on the On the inner ring, when installed on the hole, the added force must act directly on the outer ring).

Try not to affect the rolling elements. Assembly methods include hammering, press assembly, hot assembly, freezing assembly, etc.

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 dust fall into the bearing raceway. Do not directly hit the inner and outer rings of the bearing with a hammer or punch. So as not to affect the matching accuracy of the bearing or cause damage to the bearing.

② Screw press or hydraulic press assembly method For bearings with large interference tolerances, screw press or hydraulic press can be used to assemble them. Before pressing, the shaft and bearing should be leveled and applied with a little lubricating oil. 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 loading method: The hot loading method is to heat the bearing in oil to 80℃-100℃, expand the inner hole of the bearing and then fit it onto the shaft, which can prevent the shaft and bearing from being damaged. The hot-fitting method is not applicable to bearings with dust covers and sealing rings that are already filled with grease.

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

(4) When assembling a thrust ball bearing, the tight ring and the loose ring should first be distinguished. The inner diameter of the tight ring is slightly smaller. The assembled tight ring and the shaft remain relatively stationary during operation. It always leans against the shaft. steps or hole end faces, otherwise the bearing will lose its rolling action and accelerate wear.