Introduce five commonly used rolling bearings


1. Deep groove ball bearings This type of bearing is ge […]

1. Deep groove ball bearings
This type of bearing is generally only used to bear radial loads. Since the clearance is not adjustable, it is often used in occasions that do not require high precision and no preload, such as ordinary drilling machine spindles.


2. Angular contact ball bearings
This type of bearing can bear radial and axial loads at the same time. Since internal axial forces will be caused when bearing radial loads, they should be installed in pairs. The configurations include "back-to-back", "face-to-face", "tandem" and "Multi-joint", etc., and the rigidity of the spindle can be improved through preloading. The contact angles of this type of bearings are 15°, 25°, and 40°. Among them, the B7000CY high-precision angular contact ball bearing with a contact angle of 15° is a special bearing specially designed for the spindle of a high-speed grinding machine. In addition to changes, the rings and rolling elements are made of high-quality electroslag bearing steel. The material of the cage is phenolic laminated cloth tube with tolerance grades 5, 4 and 2. Therefore, this type of bearing has high rotation accuracy and limit speed, low friction and low temperature rise.



3. Two-way thrust angular contact ball bearings
Usually, the 230000 type two-way thrust angular contact ball bearing is used, the contact angle is 60°, and it is composed of a seat ring with lubricating oil holes, two shaft rings, a spacer ring and two sets of steel balls and cage assemblies. Choosing the proper spacer height can make the bearing assembled with the required preload.

This type of bearing can withstand bidirectional axial load, has good rigidity, low temperature rise during normal lubrication, high speed, and is easy to assemble and disassemble. As a new structure, it is currently mostly used for spindles such as grinding machines, lathes, boring machines, milling machines, and drilling machines. In use, it is often combined with double row cylindrical roller bearings.


4. Double row cylindrical roller bearing
This type of bearing can withstand large radial loads and allow high speeds. The two rows of rollers in the bearing are arranged in a cross manner, and the frequency of fluctuations during rotation can be doubled compared with that of a single row bearing, and the amplitude is reduced by 70%. There are two types of commonly used bearings of this type: NN30/W33 and NN30K/W33 two series of bearings with ribs on the inner ring and outer rings can be separated; NNU49/W33 and NNU49K/W33 series of bearings with outer rings The inner ring of NN30K/W33 and NNU49K/W33 series has a tapered hole (taper 1:12), which matches with the tapered journal of the main shaft, and the inner ring can be moved axially to expand the inner ring to reduce the Small bearing clearance even preloaded bearings. Cylindrical bore bearings usually adopt shrink fit, using interference fit to reduce bearing clearance, or achieve the purpose of preload. For NNU49 series bearings with separable inner ring, the raceway is usually finished after the inner ring is mounted with the main shaft to obtain high rotational accuracy of the main shaft.


5. Tapered roller bearings
It can bear radial and axial loads at the same time, and double-row tapered roller bearings can bear bidirectional axial loads. Due to the sliding friction between the large end of the tapered roller and the rib of the inner ring, its limiting speed is often lower than that of a cylindrical roller bearing of the same size. Hollow tapered roller bearings can use oil to cool the rollers, which reduces the temperature rise and thus increases the allowable speed. However, the manufacturing process of this kind of bearing is complicated, and the requirements for the lubrication system of the machine tool are also relatively high. Generally, it is only used on the horizontal spindle with special requirements.

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