What are the Main Structures and Properties of Needle Roller Bearings?

There are many structural types of needle roller bearings, which can be without inner ring or outer ring, or without inner ring and outer ring at the same time. Only needle roller and cage assembly. At this time, the neck surface and shell hole surface matched with the bearing are directly used as the inner and outer rolling surfaces of bearings. In order to ensure the load capacity and operation performance are the same as those of bearings with rings. , the hardness, machining accuracy and surface quality of the shaft or shell hole raceway surface shall be the same as that of the bearing ring.The main structural types are:

1. Needle roller and cage assemblies type K000000

The needle roller and cage assembly are a separate bearing element, in which each needle roller is accurately guided and maintained by the cage. This kind of bearing has no ring and bears a large load capacity with the minimum profile height. It is suitable for support structures with limited radial installation size.

2. Solid ring needle roller bearing type RNA0000 and NA0000 type

This kind of bearing has a low cross-section height and high bearing capacity. If the raceway surface of the shaft can be quenched and grinded, it is appropriate to use needle roller bearing RNA0000 type NK without inner rings. Because there is no inner ring, the shaft diameter can be increased and the rigidity can be increased, because there is no need to consider the influence of the inner ring tolerance, and the ultimate rotation accuracy can be obtained. However, if the roller surface of the shaft cannot be quenched, grinded or economical, the needle roller bearing with inner rings can be used NA0000 NKI.

3. Stamping outer ring needle roller bearing perforated HK and sealing BK

The stamping outer ring needle roller bearing is composed of a thin-walled stamping outer ring, a cage and a whole set of needle rollers. It has no inner ring, low cost and large load capacity. It is suitable for support structures with limited radial installation size. The surface of the neck matched with the bearing is quenched and is directly used as a raceway. This kind of bearing is generally pressed into the seat hole, and there is no need to position it axially. Bearings should be injected with sufficient grease before assembly, and usually cannot be lubricated after assembly.

There are two kinds of stamping outer ring needle roller bearings: full-mounted needle rollers and cages, and each structure has a perforated type and a sealed type.

Compared with the cage structure, the full-loaded needle roller structure is not equipped with a cage. When the bearing rotates, the two adjacent needle rollers are seriously rubbed, and the rotation speed is low. The needle roller is easy to tilt, causing wear and tear at the end of the ring edge of the needle roller, and even causing the bearing to freeze, resulting in bearing damage. Therefore, there is a tendency to be replaced by structures with cages.

Perforated HK and sealed BK without inner rings and cages. One end of the BK bearing is closed, which is used in the support of the neck without extension, and can withstand small axial swimming power. The end surface is sealed.

4. Needle roller bearing track rollers

The needle roller bearing track rollers have bolt type and baffle type. Bolted roller needle roller bearing products are divided into two types: cage type suitable for high-speed rotation and full-load needle roller type suitable for heavy load. The outer ring wall of the baffle roller needle roller bearing is thick, and the load capacity is large, which can withstand impact loads and is easy to install. It is widely used to support rollers, cams and rockers.

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