Roller bearing

[0009]According to the above aspects of the present invention, the end face (roller guide surface) of the collar portion on its sliding contact side with the roller is generally formed open at a certain angle with respect to a surface perpendicular to the raceway surface of the ring in order to facilitate the introduction of lubricating oil into between the roller and the roller guide surface of the collar portion. Therefore, a point of intersection with a grinding relief portion formed in the roller guide surface of the collar portion is geometrically easiest to touch the end face of the roller. On the other hand, since the contact side of the roller end face to be slidingly contacted with the collar portion is formed at right angles to the outside diameter surface of the roller, a point of intersection between a connecting portion (chamfer portion), which connects the outside diameter surface of the roller with the end face of the roller, and the end face of the roller is geometrically easiest to touch the collar portion.

[0010]Also, since lubricating oil existing in a portion, where the end face of the roller and collar portion is contacted with each other, is pulled into a small clearance between them due to the viscosity thereof, the shape of the mutual contact portion between the roller end face and collar portion may preferably be formed to have a clearance before and behind the mutual contact portion. Especially, because the shape of the end face of the roller is formed as a continuously curved shape, there is eliminated the possibility that an oil film can be cut due to high surface pressure occurring locally in the mutual contact portion, thereby being able to produce the oil film positively. Thanks

In the roller bearing of this type, in case where the ring is rotated at a high speed, there is generated frictional heat between the collar portion and roller, thereby raising a possibility that seizure can occur in the collar portion and roller.

However, in both of the above-mentioned conventional roller bearings, the end face of the roller an