How to design needle bearing

Needle roller bearings are mostly used in the working environment of low speed, swing motion or static load. The choice of needle clearance and internal and external tolerance in the design of this kind of bearings also has a lot to do with their working performance. The following introduces the design method and basic knowledge of needle roller bearing:

First of all, understand the requirements of the full needle roller bearing. Its general tolerance level is G2, and the group difference is 0 ~ 7um. Its needle roller is arc prime, but this design method is also very beneficial to the straight plain line needle roller. The determination of circumferential clearance s means that the average clearance of each needle is 5um. When its needle diameter is less than or equal to 305mm, the so-called minimum s cannot be less than 0.1mm, that is to say, the number of needles should be less than 20. On the contrary, when the diameter of the full needle bearing is greater than 3.5mm, the minimum s cannot be less than 0.15mm, that is, the number of needles must be less than 30, so its s value can only be 0.15mm.

Then it is the determination of the diameter of the central circle of the needle. This design is mainly manifested in the ideal state of the bearing, and the needle can be evenly distributed on the diameter of the central circle of the needle, and the diameter of the central circle of the needle can be calculated by its own formula. Then, the original radial clearance of needle bearing is determined. The design of the original diameter clearance mainly depends on the selection of the diameter of the inner raceway and the diameter tolerance of the outer raceway. Of course, this method is also based on the usual matching method and long-term production experience, so as to get more effective original radial clearance.

Finally, the limit speed is determined. Since the needles are sliding against each other in the opposite direction, it also needs to generate great friction and heat to keep them. Also, because the needle gap is small, the corresponding grease storage space is also small, and the lubrication interval time will be shortened.