NSK tapered roller bearing low friction technology evolution
In the frictional resistance theory of tapered roller bearings, Aihara classifies the friction of tapered roller bearings as: 1) rolling friction TR of the outer ring raceway surface and the roller rolling surface; 2) sliding of the roller end face and the inner ring rib Friction TS; 3) sliding friction between the roller and the cage (very low); lubricating oil stirring resistance. Among them, TR and TS are the main friction of tapered roller bearings, and also the main control item to achieve low friction. For further friction reduction, focus on the lubrication resistance of the lubricant.
First generation tapered roller bearing
The TS is reduced by optimizing the contact position of the roller end face with the rib and improving the surface roughness of the roller end face and the inner ring large rib. Compared with the conventional standard bearing, the entire operation process is reduced by 20%.
Second generation tapered roller bearing
Reduce TR by optimizing the internal structural parameters of the bearing. When bearing structural parameters (such as contact angle, number of rollers, roller length, roller diameter, etc.) are designed with low friction as the focus, other required properties (such as life and stiffness) of the bearing are reduced. Therefore, tapered roller bearings are usually used in pairs. By optimizing the dimensions of the two sets of bearings and balancing the structural parameters of the bearings, the purpose of reducing friction can be achieved under the premise of ensuring bearing life and rigidity.
Third generation tapered roller bearing
The bearing size is reduced by applying the newly developed long-life material and heat treatment technology (TF series) to further reduce the friction than the second generation bearing.
Fourth generation tapered roller bearing
Optimize the convex shape to suppress the occurrence of edge load (increased local surface contact stress). Compared with the third generation of the fourth generation tapered roller bearing, the life is improved regardless of the normal load or heavy load; the rigidity is improved; the bearing weight loss is about 20%, and the friction is reduced by 30%.
Fifth generation tapered roller bearing
Focus on the lubrication resistance of the lubricant. A plastic cage is used to control the amount of oil flowing into the bearing, and the shape of the plastic cage is determined based on the oil flow analysis result.
The small end oil inflow area is reduced by reducing the distance between the retainer and the inner ring small rib; the inner space of the bearing is filled by the cage. Under the condition of ensuring sufficient lubrication, the friction can be reduced by 20%.
Sixth generation tapered roller bearing
Generally used in the gearbox high torque output (intermediate axis and differential axis). At low speeds, TS significantly affects the total frictional moment and still aims to further reduce TS, further improving the surface contact conditions between the roller end face and the inner rim. At low speeds, the maximum friction is reduced by 60% and the maximum speed is reduced by 20% over the entire speed range.
Reprinted from the network