NTN has developed a thrust needle roller bearing with a dmn value (bearing pitch diameter (mm) × rotation speed (rpm)) of 1.5 million and high speed operation. In the product with a bearing pitch diameter of 71.5mm, the rotation speed reached 21,000 rpm, "the highest in the world" (the company). This product is used in hybrid vehicle engine units, AT (automatic transmission) and CVT (continuously variable transmission) to meet the requirements of high speed. In addition, it can also be used on ordinary industrial machines.
This time, the company has reduced the surface roughness of the cage pockets in contact with the end faces of the rollers, and also improved the shape of the cage so that the contact state of the two does not hinder the movement of the rollers. Further, by changing the shape of the end face of the roller to a curved surface having a radius of curvature R, it is possible to reliably make point contact with the surface of the holder pocket at a center point where the rotational speed is slow. Through these measures, the wear and sintering are reduced. The maximum number of revolutions of the bearing has increased by 67% from the original 900,000.
In addition, the temperature increase of the bearing at the time of high speed rotation is further reduced. The product has an oil temperature of 80 ° C and a dmn value of 900,000. The temperature rise of the bearing during operation is reduced by 35% compared with the original product.
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Dtmade Manufacturing Co., LTD , https://www.dtmade.com