Such bearings are mostly used in machine tool spindles, such as nn3020k (original code 3182120) bearings. Its installation is basically the same as that of the tapered hole spherical roller bearing, and the tightness of the fit is achieved by the reduction of the radial clearance of the bearing before and after installation. In installation, the radial clearance reduction is generally replaced by measuring the axial displacement of the bearing inner ring to the shaft. Axial displacement is calculated as follows: l=k(eh—en+a) (mm) where eh—original radial clearance en—bearing assembly radial clearance a—constant, is 0.01k— The value of proportionality factor k, which depends on the wall thickness of the hollow shaft, and the diameter d of the main shaft matched with the bearing, and the average outer diameter d of the journal matched with the main shaft. related. During installation, the axial displacement of the bearing can be measured by contacting the end face of the inner ring of the bearing with a micrometer. It depends on the thickness adjustment of the inner and outer spacers of the two bearings. There are three ways to determine the thickness difference between the inner and outer spacers of the two bearings: The first method is to measure the first place the bearing on the round seat body, and press an iron block with a weight equal to a (preload) on it to eliminate the bearing clearance. The steel ball and the raceway produce a certain elastic deformation, and then use a dial indicator to measure the size difference between the end faces of the inner and outer rings of the bearing. When the bearing is installed back to back, the size difference △k1 between the inner and outer rings on the wide end face should be measured for both bearings; when the bearing is installed face to face (narrow end face is opposite), the inner and outer rings on the narrow end face should be measured for both bearings. Ring size difference △k2; when the bearings are arranged in series, measure the size difference between the inner and outer rings on one side of the wide end face for one bearing, and measure the size difference between the inner and outer rings on the narrow end face side for the other bearing. A pair of bearings mounted back to back. The measured moment of the inner and outer rings at the wide end face of one bearing is +0.07mm, the size difference between the inner and outer rings at the wide end face of the other bearing is +0.08mm, and the thickness of the inner spacer is 6.25mm. Find the thickness of the outer spacer. Thickness of outer spacer = 6.25 + (0.07 + 0.08) = 6.40 (mm) When measuring the size, each bearing is measured three times with an interval of 120°, and the average value is taken at the end. A pair of bearings mounted in series. The size difference between the inner and outer rings at the wide end face of one bearing is +0.16mm, the size difference between the inner and outer rings at the narrow end face of the other bearing is -0.12mm, and the thickness of the inner spacer is 6.25mm. Find the thickness of the outer spacer. Thickness of outer spacer=6.25+(0.16-0.12)=6.29(mm) This method mainly depends on practical experience to determine the thickness of inner and outer spacer. There are three common feeling methods; one is to first drill three small holes with a diameter of 2-3mm on the cylindrical surface of the outer spacer according to 120°, and add the pair of two-sided sleeves according to their installation methods (back-to-back, face-to-face or in series). For the inner and outer spacers, press an iron block equal to the preload on the upper part of the bearing, and then use a small rod of about ø1.5mm to touch the inner spacer through three small holes in sequence to check the resistance of the inner and outer spacers between the two ends. By hand, the resistance of the inner and outer spacers should be similar, otherwise the end face of the spacer can be ground. The second is to compress the two sets of bearings with the left middle finger and index finger (approximately equal to about 50 preload) to eliminate all their gaps, and the right finger to move the inner and outer spacers respectively to determine whether the resistance is similar. The third is to pinch the two sets of bearings with the thumb and forefinger of both hands to eliminate all the gaps. Use one middle finger to extend into the inner hole of the bearing, and move the originally offset inner spacer to check whether its resistance is similar to the outer ring. The third is the spring preload method. For bearings installed in series, in addition to determining the thickness of the inner and outer rings by the measurement method or the feeling method, several cylindrical springs should be used to act on the inner and outer rings of the bearing during assembly to achieve preloading. The calculation formula of the spring is as follows. In the formula, d——spring wire diameter (cm) This article comes from: d——spring average diameter (cm) r——spring allowable stress (40000-70000n/c㎡) n——cylindrical spring quantity
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