Needle Roller Bearing Considerations
Roller bearing is roller bearing with cylindrical roller, and its diameter is thin and long. This roller is called a rolling pin. Although has a small cross-section, bearing still has high load capacity, needle bearing with fine and long roller (roller diameter D 5 mm or less, acuity 2.5 L/D, L) for the roller length, so the radial structure is compact, its diameter and load capacity at the same time, with other types of bearing outside diameter to a minimum, especially suitable for 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. The bearing can only bear the radial load.
Full roller bearings are installed, usually through auxiliary sleeve. At this time, the auxiliary roller or auxiliary sleeve hold needle don't fell out of the needle, journal with its own chamfering needle lift, as the needle roller bearing on the shaft neck slowly moving into, the auxiliary roller or auxiliary sleeve out slowly, until outfit to the job position.
The outer diameter of auxiliary roller and auxiliary sleeve shall be 0.1 to 0.3mm in diameter. When installation, the surface coated with grease inside the bearing outer ring first, against the tight inner surface needle needle: (in the last one should be gaps), then replace the shaft neck of the roller bearing inner ring or auxiliary sleeve into the outer ring hole, and make it face alignment installed shaft end face or installed on the shaft bearing inner ring end face, and then use pressure on the press or hammer knock.
Needle roller bearing and it can be installed, apply a thin layer of lubricating oil, the auxiliary sleeve diameter set into the bearing outer ring and the auxiliary sleeve and bearing outer ring form a circular hole, and then install needle in the annular aperture. After the rolling needle is installed, the auxiliary sleeve will be rolled out with the working shaft.
For the rolling needle bearing without inner ring or outer ring, the rolling surface of the shaft or shell can be coated with a thin layer of grease at the time of installation, and the needle shall be attached to the grease of the installation site in turn. When the last needle is attached, the clearance should be left. The size of the gap shall be 0.5mm on the circumference of the roller bearing. You can't squeeze the last needle into the ball, or you can put a needle on it, because when it's hard to squeeze, the bearing will be stuck. When less loading, the clearance is too large, easy to cause the bearing to roll the needle and break. For the roller bearing with the outer ring only, because the outer ring wall is very thin, do not use the hand hammer to knock the installation, should use the press to press in. Because of the hammering, the pressure is not uniform and easy to make the outer ring of the needle bearing deformation.
Needle roller bearing capacity big, applicable to the limited size of installation supporting structure, the journal as rolling surface hardening on the surface, bearing force fit in a hole, not for axial positioning.
Bearing before installation should be injected into the right amount of grease, under normal circumstances, after the assembly no longer BK type bearing lubrication for shaft neck without out of the bearing, encloses the seal effect, and can withstand the small axial winding.