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Correct assembly of machine tool bearings

2020-03-28

& nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; bearings are used to support parts, and also used to support the rotating parts on the shaft. The types of bearings are divided into sliding bearings and rolling bearings according to the friction properties; according to the direction of bearing loads, they are divided into radial bearings, push bearings, centripetal thrust bearings, etc. < nbsp; '& nbsp;' & nbsp; '& nbsp;' & nbsp; '& nbsp;' & nbsp; '& nbsp;' & nbsp; '& nbsp;' & nbsp; '& nbsp;' & nbsp; '& nbsp;' & nbsp; '& nbsp;' & nbsp; '& nbsp;' & nbsp; '& nbsp;' & nbsp; '& nbsp;' & nbsp; '& nbsp;' & nbsp; '& nbsp;' & nbsp; '& nbsp;' & nbsp; '& nbsp;' & nbsp; Sliding bearing is a kind of bearing with sliding friction property, which is characterized by stable operation, low noise, bearing heavy load and large impact load. According to the different structure, it can be divided into integral type, split type and tile type. < / P > & nbsp; & nbsp; & nbsp; & nbsp; (1) assembly of integral sliding bearing; Integral sliding bearing, commonly known as shaft sleeve, is also the simplest form of sliding bearing. It is mainly assembled by pressing in and hammering. In special occasions, hot assembly method is adopted. Most shaft sleeves are made of copper or cast iron. Assembly should be careful. Wooden hammer or hammer can be used to knock wood blocks for assembly. When the tolerance of interference dimension is large, press in. No matter knock in or press in, the oil groove and oil hole should be in the required position after assembly. < / P > & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; the inner hole of the bearing deformed after assembly should be repaired, and the smaller size can be reamed, and the larger size can be scraped. At the same time, pay attention to control the fit clearance with the shaft within the tolerance range. In order to prevent the shaft sleeve from rotating when working, the contact surface between the shaft sleeve and the box body is equipped with positioning pin or slotted screw. Due to the different hardness of casing and sleeve materials, it is easy to make the drill bit lean to the side of soft material when drilling. The solutions are as follows: first, punch the hard material with sample before drilling; second, use short drill bit to increase the rigidity of drill bit. The split bearing is also called split bearing, which has the characteristics of simple structure, convenient adjustment and disassembly. Two pieces of bearing are inlaid on the bearing bush, and the reasonable clearance is adjusted by gasket at the joint. < / P > & nbsp; & nbsp; & nbsp; & nbsp; ① assembly of bearing shell and bearing body < / P > & nbsp; & nbsp; & nbsp; the upper and lower bearing shells must be in good contact with the bore in the bearing body. If it does not meet the requirements, scrape the back of the bearing shell with the bore in the bearing shell as the benchmark, and make the steps at both ends of the bearing shell close to the two ends of the bearing body. As long as the split surface of the bearing shell is 0.1 mm higher than that of the bearing body, there is no need to scrape it. Both ends of the bearing are not allowed to be positioned in the bearing with or without radial displacement of the bearing shell. < / P > & nbsp; & nbsp; & nbsp; & nbsp; ③ matching scraping of bearing bush < / P > < P style = 'line height: 2; '> for split type bearing shells, the matching shaft grinding points are generally used. Generally, the bearing shells are scraped off first, and then the upper bearing shells are scraped. In order to improve the efficiency, the bearing shells and covers can not be installed when scraping the bearing shells. When the contact points of the lower bearing shells basically meet the requirements, the upper bearing shells and upper covers are pressed tightly, and the contact points of the lower bearing shells are further corrected when scraping and grinding the upper bearing shells. With the increase of scraping times, the tightness of the shaft can be adjusted by changing the thickness of the gasket. When the bearing cover is fastened, the shaft can be easily rotated without obvious clearance, and the contact point meets the requirements. < / P > & nbsp; & nbsp; & nbsp; & nbsp; ④ measurement of bearing clearance < / P > & nbsp; & nbsp; & nbsp; & nbsp; the size of bearing clearance can be adjusted by the gasket at the split or by directly scraping the bearing bush. Lead pressing method is usually used to measure bearing clearance. Take several pieces of lead wire with diameter larger than bearing clearance and put them on journal and split surface. Then screw down nuts to make split surface compact. Then screw off nut, take down bearing cover and carefully take out flattened lead wire. After taking a section, micrometer can measure thickness. According to average thickness of lead wire, bearing clearance can be known. Generally, the clearance of the bearing should be 1.5-2.5 & permil; (mm) of the shaft diameter, and the smaller clearance value should be taken when the diameter is larger. If the shaft diameter is 60mm, the bearing clearance should be between 0.09-0.15mm.

    

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