Needle bearing is a roller bearing with cylindrical rollers, which are both thin and long relative to their diameter. This type of roller is called a rolling needle. Despite having a small cross-section, bearings still have high load bearing capacity, and needle roller bearings are equipped with thin and long rollers (roller diameter D ≤ 5mm), L/D ≥ 2.5, where L is the length of the roller), therefore the radial structure is compact, with the same inner diameter size and load capacity as other types of bearings, and the smallest outer diameter, making it particularly suitable for support structures with limited radial installation dimensions.
According to different usage scenarios, bearings or needle and cage components without inner rings can be selected. At this time, the surface of the shaft neck and outer shell hole that match the bearing directly serve as the inner and outer rolling surfaces of the bearing. To ensure the same load capacity and operating performance as bearings with rings, the hardness, machining accuracy, and surface quality of the surface of the shaft or outer shell hole raceway should be similar to that of the bearing ring raceway. This type of bearing can only withstand radial loads.
Classification of needle roller bearings
In addition to those listed in the catalog, needle roller bearings that can be used in general engineering, such as open stamped outer ring needle roller bearings, closed stamped outer ring needle roller bearings, needle roller bearings with inner ring and without inner ring needle bearings/without inner ring and cage needle roller bearings, and needle roller bearings with and without cages filled with cages
Drawn Cup
Stamped outer ring needle roller bearings are needle roller bearings with thin stamped outer rings. Its main feature is that the cross-sectional height is very low and the load-bearing capacity is high. Mainly used for bearing configurations that are compact in structure, inexpensive in price, and cannot be used as raceways for needle roller cage components. The bearings and bearing boxes must be installed in an interference fit manner. If axial positioning functions such as box shoulders and stop rings can be omitted, then the bore inside the bearing box can be made extremely simple and economical. The stamped outer ring needle roller bearings installed at the shaft end have double-sided open type and single-sided closed type. The base end face of the closed stamped outer ring can withstand minimal axial guiding force. Stamped outer ring needle roller bearings generally do not have inner rings attached. In situations where the journal cannot be hardened or ground, the inner ring listed in the table can be used. The hardened steel plate outer ring of the stamped outer ring needle roller bearing cannot be separated from the needle roller cage assembly. The free space for storing lubricants can extend the interval for supplementing lubrication. Bearings generally adopt a single row design. Except for wider specification bearings such as NA69 series, which are equipped with two needle roller cage components. The outer ring of the bearing has lubricating oil holes. According to user needs, all single row stamped outer ring needle roller bearings with a shaft diameter greater than or equal to 7mm can be equipped with outer rings with lubricating oil holes (code suffix AS1). In situations where oil seals cannot be installed due to space limitations, open or closed end oil seal stamped outer ring needle roller bearings (3 to 5) can be provided. These types of bearings are equipped with friction type oil seals made of polyurethane or synthetic rubber, filled with lithium based grease with good rust resistance, suitable for operating temperatures of -20 to+100 ℃. The inner ring of the oil sealed bearing is 1mm wider than the outer ring, which ensures that the oil seal works well and prevents contamination of the shaft when there is a slight displacement of the bearing relative to the bearing housing. The inner ring of the bearing also has lubrication holes, which can be supplemented with lubrication by the outer or inner ring according to the needs of the bearing configuration.
Solid Ferrule
A solid ring needle roller bearing is composed of one or two rings and a needle roller group with a cage. According to different application scenarios, bearings can be divided into those with inner rings or those without inner rings. Therefore, solid ring needle roller bearings can meet the requirements of light weight, small space occupation, and high power transmission. Solid ring needle roller bearings have a smaller volume and higher load-bearing capacity. Structural type: outer ring double retaining edge (or double locking ring) with cage needle roller bearing NA The NAV and NKI models can be equipped with inner and outer rings (with locking rings, complete set of needle rollers, and retainers) respectively, with high permission speed and can be divided into single and double rows. If the shaft cannot be used as a raceway, that is, if it is impossible or uneconomical to harden the shaft and grind it, such needle roller bearings with inner rings can be used.
Features NA NKI type bearings without inner rings are RNA NK type needle roller bearings. This type of bearing has no inner ring and is suitable for supporting structures with limited radial installation dimensions. The journal that matches the bearing serves directly as the rolling surface. As the axis of the raceway surface, it must be hardened and ground, and only when it is machined to the appropriate size and shape accuracy, can the entire set of needle roller bearings have a higher lifespan and operating accuracy. Meanwhile, due to the absence of an inner ring, the diameter of the shaft can also be appropriately increased, thereby increasing rigidity.
Combination needle roller bearings
Combination needle roller bearings are bearing units composed of radial needle roller bearings and thrust bearing components. They have a compact structure, small volume, high rotational accuracy, and can withstand both high radial loads and certain axial loads. And the product has diverse structural forms, wide adaptability, and is easy to install. Combination needle roller bearings are widely used in various mechanical equipment such as machine tools, metallurgical machinery, textile machinery, and printing machinery, and can make mechanical system design very compact and flexible.
Thrust needle roller bearing
The thrust bearing consists of a thrust cage assembly with needle or cylindrical rollers or balls and a thrust washer. The needle roller and cylindrical roller are held and guided by the thrust cage. When used together with different series of DF thrust bearing washers, many different combinations can be provided for the bearing configuration. Due to the use of high-precision cylindrical rollers (needle rollers) to increase the contact length, this bearing can achieve high load capacity and high stiffness in a very small space. Another advantage is that if the surfaces of adjacent parts are suitable as raceway surfaces, washers can be omitted, making the design compact, DF thrust needle roller bearings and thrust cylindrical roller bearings use cylindrical surfaces with modified needle and cylindrical rollers, which can reduce edge stress and improve service life.
