A needle bearing is a roller bearing with a cylindrical roller that is thin and long relative to its diameter. This type of roller is called a needle roller. Despite the small cross-section, the bearing still has a high load bearing capacity, and the needle bearing is equipped with a thin and long roller (roller diameter D ≤ 5 mm, L / D ≥ 2.5, L is the roller length), so The radial structure is compact, its inner diameter size and load capacity are the same as other types of bearings, the outer diameter is the smallest, and it is especially suitable for support structures with limited radial mounting dimensions.
Depending on the application, bearings or needle roller and cage assemblies without inner ring can be used. The journal surface and the housing hole surface that match the bearing directly serve as the inner and outer rolling surfaces of the bearing to ensure load capacity and running performance. As with ferrule bearings, the hardness of the raceway surface of the shaft or housing bore, the machining accuracy and surface quality should be similar to the raceway of the bearing ring. This type of bearing can only withstand radial loads.
Types of
In addition to the catalogue, it can be used for general engineering bearings, such as: open stamped outer ring
Needle roller bearings, closed drawn cup needle roller bearings, needle roller bearings with inner ring and needle roller bearings without inner ring / cage without needle bearing for inner ring, with cage and without cage filled with needle roller bearings. SKF can also supply various types of needle roller bearings, 1, needle roller cage assembly 2, non-ribbed needle roller bearings 3, self-aligning 4, combined needle roller / ball bearing 5, combined needle roller / thrust ball bearing 6 , combined needle roller / cylindrical roller thrust bearing.
Drawn outer ring
The drawn cup needle roller bearings are needle bearings with a thin stamped outer ring. Its main features are low cross-section height and high load carrying capacity. Mainly used for bearing arrangements that are compact, inexpensive, and the bore of the bearing housing cannot be used as the raceway for the needle roller cage assembly. The bearing and bearing housing must be installed in an interference fit. If the axial positioning function such as the box shoulder and the stop ring can be omitted, the inner hole of the bearing housing can be made extremely simple and economical. The drawn cup needle roller bearings mounted on the shaft end are open on both sides and closed on one side. The base end face of the closed stamped outer ring can withstand small axial guiding forces. Drawn cup needle roller bearings generally do not have an inner ring. In the case where the journal cannot be hardened and ground, the inner ring listed in the table can be used. The hardened steel outer ring of the drawn cup needle roller bearing is inseparable from the needle roller cage assembly. The free space to store the lubricant can extend the relubrication interval. Bearings are generally designed in a single row. Except for the wider series of bearings 1522, 1622, 2030, 2538 and 3038, they are equipped with two needle retainer assemblies. The outer ring of the bearing has a lubrication hole. All single row drawn cup needle roller bearings with a shaft diameter greater than or equal to 7 mm can be equipped with an outer ring with a lubrication hole (code suffix AS1), depending on the user's needs. Oil-filled drawn cup needle roller bearings can be supplied with open-end or closed-end oil-sealed drawn cup needle bearings (3 to 5) where oil seals cannot be installed due to space constraints. These bearings are equipped with a frictional oil seal of polyurethane or synthetic rubber filled with a lithium-based grease with good rust resistance for an operating temperature of -20 to +100 °C. The inner ring of the oil-sealed bearing is 1 mm wider than the outer ring. This makes the bearing work well in the case of a slight displacement of the bearing shaft relative to the bearing housing without causing the bearing to be contaminated. The inner ring of the bearing also has lubrication holes, which can be relubricated by the outer ring or the inner ring according to the needs of the bearing arrangement.
Physical ferrule
Solid ferrule needle bearings consist of one or two ferrules and a needle set with a cage. Depending on the application, it can be divided into bearings with or without inner ring. Therefore, the physical ferrule needle roller bearing can meet the requirements of light weight, small space occupation and large transmission power. Solid ferrule needle bearings have a small volume and high load carrying capacity. Structure type outer ring double rib (or double lock ring) with cage needle roller bearings NA, NAV, NKI type can be installed inner ring and outer ring (with lock ring, full set of needle roller and cage), high speed, It is divided into single column and double column. If the shaft cannot be used as a raceway, that is, if the hardening of the shaft is impossible or uneconomical, then the needle bearing with inner ring can be used. The NA, NKI bearing without the inner ring is RNA. , NK type needle roller bearings. Such a bearing has no inner ring and is suitable for a support structure in which the radial mounting size is limited, and the journal that matches the bearing directly serves as a rolling surface. As the axis of the raceway surface, the hardware must be hardened and ground, and the entire needle roller bearing can only have a high life and running accuracy when it is machined to the appropriate size and shape accuracy. At the same time, since there is no inner ring, the diameter of the shaft can be appropriately increased, thereby also increasing the rigidity.
Combined type
The combined needle roller bearing is a bearing unit composed of a combination of a radial needle bearing and a thrust bearing component. The compact needle size and high rotation precision can withstand a high axial load while bearing a certain axial load. And the product structure is diverse, adaptable and easy to install. Combined needle roller bearings are widely used in various mechanical equipment such as machine tools, metallurgical machinery, textile machinery and printing machinery, and can make the mechanical system design very compact and dexterous.
Thrust type
The thrust bearing consists of a thrust cage assembly with a needle or cylindrical roller or ball and a thrust washer. The needle roller and the cylindrical roller are held and guided by the thrust cage. When used with different series of DF thrust bearing washers, many different combinations are available for bearing configurations. Due to the use of high-precision cylindrical rollers (needle rollers), the contact length is increased, so that the bearing can achieve high load capacity and high rigidity in a small space. Another advantage is that if the surface of the adjacent part is suitable for the raceway surface, the washer can be omitted, and the design can be compact. The cylindrical surfaces of the needle roller and the cylindrical roller used for the DF thrust needle roller bearing and the thrust cylindrical roller bearing are The profiled surface reduces edge stress and increases service life.
advantage
Needle roller bearings are equipped with thin and long rollers (the length of the roller is 3 to 10 times the diameter and the diameter is generally not more than 5 mm), so the radial structure is compact, and the inner diameter and load capacity are the same as those of other types of bearings. The smallest diameter, especially suitable for radial support size limited support structure. Needle roller bearings should be combined with bearing rings and applications depending on the application. A needle bearing is a bearing unit that combines a radial needle bearing and a thrust bearing component.