Flat needle roller bearing is a cylindrical roller of roller bearings, relative to its diameter, roller is thin and long.
This is called needle roller.
Although has a small cross-section, bearing still has high load capacity, flat needle bearing with fine and long roller (
Roller diameter D 5 mm or less, the L/D 2 or more.
5, L for roller length)
, so the radial structure is compact, its inner diameter size and load capacity at the same time, with other types of bearing outside diameter is small, particularly applicable to the limited size of the radial installation supporting structure.
According to the use of different occasions, can be used without inner ring of the bearing or needle roller and cage components, at this time to suit the bearing surface of the surface of the shaft and the shell hole directly as inner and outer rolling bearing surface, in order to ensure the load capacity and operation performance and you have the same ring bearing, axis or shell hole hardness on the surface of the raceway, machining accuracy and surface quality should be as a bearing ring raceway.
These bearings can bear radial load only.
Application in mechanical equipment in the bearing temperature is too high, such as 'fever' is not normal, is common and harm of common mechanical equipment fault, for unknown reasons, improper handling, often the wasted effort, directly the service life of rolling bearing manufacturer of needle roller bearing, increase maintenance costs, and even cause bearing burning phenomenon, bearings with kinds of selection, should according to the size of the bearing type and size, load and the direction and the nature of the load, etc.
Correct selection of bearing fit should guarantee the bearing function, prevent the inner ring and shaft, outer ring and shell hole relative rotation occur at work.
Generally speaking, when the direction of the working load constant, turn the circle than in those without moving coil have a tighter fit, because the rotating ring spinning under load, rather than moving coil under partial load.
When the higher the speed, the stronger the more load and vibration, should choose the more tight fit.
When the bearing installed on thin-walled shells or hollow shaft, also should use a tight fit.
But tight fit is bad, maybe because of inside and outside the circle the elastic expansion and contraction of the outer ring of bearing internal clearance diminish or even disappear completely, also may be due to the combination of the shaft and hole on the surface of the irregular shape, or uneven rigidity and bearing inner and outer circle irregular deformation, which will damage the bearing's normal work.
Tight fit still can make installation difficulties, especially for heavy machinery, with modern high precision grinding machine, precision lathe introduce adaptive control technology, according to the change of cutting condition, automatically adjust the working parameters, the bearing can maintain good working condition in the processing process, resulting in high machining accuracy and surface roughness, the smaller the at the same time also can increase the service life of bearing and the bearing noise.