What is the difference between cylindrical roller bearings and needle roller bearings?

 

Cylindrical roller bearings

Cylindrical roller bearings belong to precision bearings, and the flange guidance of the precision-sorted roller post bearing is composed of a cage, rollers and a guide shaft ring, which can be separated from another bearing ring and belongs to a separable bearing. This kind of bearing is more convenient to install and disassemble, especially when the inner and outer rings, shafts and housings are required to be interference fits.

 

These bearings are in linear contact with the raceways. The load capacity is large, and it mainly bears radial loads. Only single row bearings with flanges in both the inner and outer rings can carry a small constant axial load or a large intermittent axial load; Compared with other accumulation bearings with the same dimensions, this type of bearing has the characteristics of high load, bottom noise and high speed, and the friction between the rolling element and the ring flange is small, and it is suitable for high-speed rotation. Ideal for use with all kinds of precision machinery and mining rolling mill machinery. However, the shafts, rolling elements and other related parts that are matched with such bearings need to be precision machined.

 

According to whether the ring has a flange or not, it can be divided into NU, NJ, NUP, N, NF and other single-row cylindrical roller bearings, and NNU, NN and other double-row cylindrical roller bearings. The bearing is a separable structure with an inner ring and an outer ring.

 

Cylindrical roller bearings with no flanges in the inner or outer rings can be moved axially and can be used as free-end bearings. Cylindrical roller bearings with double flanges on one side of the inner and outer rings and a single flange on the other side of the ferrule can withstand a certain degree of axial load in one direction. Generally, steel plate stamping cages are used, or copper alloy turned solid cages. However, some cages are formed using polyamide.

 

Open-drawn cup needle roller bearings

 

Needle roller bearings

Needle roller bearings are roller bearings with cylindrical rollers, which are both thin and long relative to their diameter. Such rollers are called needle rollers. Despite their small cross-sections, the bearings have a high load capacity, and needle roller bearings are equipped with thin and long rollers (roller diameter D≤5mm, L/D≥2.5, L is the roller length), so the radial design is compact, and their inner diameter and load capacity are the same as those of other types of bearings, with the smallest outer diameter, which is particularly suitable for support structures with limited radial mounting dimensions.

 

Therefore, needle roller bearings are mainly used in space-constrained occasions, so they are widely used in automobiles, motorcycles, and textile machines. And the inner ring of the needle roller is optional, to put it bluntly, if the hardness and roughness of the shaft meet the requirements, you can not match the inner ring (the space is limited), but if the machining degree of the shaft is relatively low, or relatively soft, you need to match the inner ring as a raceway.

 

The differences between cylindrical roller bearings and needle roller bearings are as follows:

 

1. The rolling element of the cylindrical roller bearing is a tapered roller; The rolling elements of needle roller bearings are needle-shaped rollers;

 

2. The structure of cylindrical roller bearings is larger than that of needle roller bearings;

 

3. In addition to the radial force, the cylindrical roller can also withstand the axial force, while the needle roller bearing can only bear the radial force;

 

4. Cylindrical roller bearings are divided into single rows, double rows and multiple rows, which are applied to different environments and occasions;

 

5. The working speed of cylindrical roller bearings is higher than that of needle roller bearings;

 

6. Cylindrical roller bearings are generally made of high-quality bearing steel and special steel; The thin-walled needle roller bearings are stamped from steel plates. 

 

When to use it

 

In mechanical design, the size of the shaft is generally determined first, and then the rolling bearing is selected according to the size of the shaft. However, when the bearing is limited in the diameter direction of the machine, needle roller bearings, ball or roller bearings of the extra light and ultra-light series are selected; When the axial position of the bearing in the machine is restricted, narrow or extra-narrow series of ball or roller bearings are available.

 

Radial needle roller and cage components, stamped outer ring needle roller bearings, solid ring needle roller bearings, thrust needle roller bearings are widely used in the transmission system, steering system, motorcycle engine connecting rod of automobiles and construction machinery, etc., and are suitable for occasions with small space and large bearing capacity. Needle roller bearings are equipped with thin and long rollers (the roller length is 3~10 times the diameter, and the diameter is generally not more than 5mm), so the radial structure is compact, and its inner diameter size and load capacity are the same as those of other types of bearings, and the outer diameter is the smallest, which is especially suitable for the support results where the radial installation size is limited.