1. Problems existing in the contact between the base surface of the tapered roller ball and the big edge

In large cone Angle tapered roller bearings, the inner ring raceway, outer ring raceway and the outer diameter of the roller are mainly subjected to radial load, and theoretically in the state of pure rolling.The included Angle between the outer ring raceway bus and the axis line of the bearing studied in this paper is about α = 25° ~ 29°, so it is called the large-cone Angle tapered roller bearing.The bearing capacity of axial load is higher than the general tapered roller bearing, mainly used to bear radial and axial combined load with axial load in one direction.

The conventional design and machining methods of tapered roller ball base surface do not meet the service life requirements of tapered roller bearings.The main problems and status quo  are:

(1) The wear of the big edge surface of the inner ring and the base surface of the roller ball are not uniform, and the Sr value of the base surface of the roller ball is large.

(2) abnormal temperature rise often occurs in the use of bearings;

(3) big cone Angle conical roller ball base surface contact with the inner ring big guard position is unusual, the contact position and sometimes appear inside is big guard outside and roller ball between the edge of the hole diameter, and sometimes appear inside is big the inside of the rim with roller ball surface radial chamfering edge, between the roller ball contact position between base surface and inner ring big guard often appear uncertain phenomenon;

(4) Cracking phenomenon sometimes occurs at the big edge of the bearing inner ring.Therefore, in order to effectively improve the service life of this kind of large-cone Angle tapered roller bearing, the influence of the base surface shape of the roller ball on the bearing performance must be solved at first.

According to the structural characteristics of the large cone Angle tapered roller bearing and the basic law of stress state and deformation after the wear of the roller, inner ring raceway and big flange, the shape of the bearing tapered roller ball base plane was optimized and improved.

2. Analysis of the contact state between the base surface of tapered roller ball and the big rim of inner ring

The base surface of the roller ball and the big flange of the inner ring are working surfaces. The sliding friction produced by them during working will cause serious friction and wear, burns or stress concentration when the lubrication is poor or the contact position is unreasonable, which will lead to the early fatigue peeling and failure of the bearing raceway, the base surface of the roller ball and the outer diameter.The shape of the tapered roller ball base surface, the hole diameter of the ball base surface and

The shape of the big rim of the inner ring is the main factor affecting the abnormal temperature rise of the big rim of the inner ring and the bearing capacity, and the contact position between the base surface of the tapered roller ball and the big rim of the inner ring is also a very important link.

The abnormal contact position and wear condition between the big rim of the inner ring and the base surface of the roller ball also affect the service life of bearings.The uneven wear phenomenon, especially the bulge at the edge of the hole diameter caused by the small size of the base surface of the tapered roller ball (as shown in Fig. 1b), can cause poor contact between the base surface of the roller ball and the big edge of the inner ring.If it is accompanied by the big flange Angle difference and surface roughness of the inner ring, the uneven wear will cause spiral wear on the big flange surface of the inner ring.Therefore, appropriately increasing the hole size on the base surface of the tapered roller ball according to the condition of the big edge of the inner ring of the bearing is conducive to equal area grinding of the two end faces of the tapered roller, and effectively ensuring the chamfering coordinate size at both ends of the tapered roller.On the other hand, it is also beneficial to improve the large flange surface of inner ring and the uneven wear degree of roller ball base surface caused by the large axial load of bearing and the large difference of SR value of roller ball base surface.

In addition, at the contact point, the size of sliding friction is related to the position of the contact point: when the circumference diameter of the contact point is small, the sliding friction is small;On the contrary, sliding friction is large.Therefore, the contact position of the roller ball base surface and the big side is in the middle, which can effectively avoid or reduce the occurrence of the big side cracking phenomenon.