Method of producing a rolling bearing race

A method of producing a rolling bearing race provided with a continuous rupture seam along at least one area of its periphery and having a seating surface and a race for rolling elements, the rolling bearing race surface being exposed before rupture along at least a portion of the intended course of the rupture seam to high-energy radiation with the local confines transerve to the intended course of the rupture seam and during rupture the surface area exposed to radiation is subjected to tensile stress by an external force, characterized in that the seating surface (2,8) of the bearing race (1,7) is exposed to the radiation and the external force is exerted as a pressure force onto the raceway surface (3,9) along an area directly opposed to the area (6,10) of the seating surface (2,8) exposed to radiation.

BACKGROUND OF THE INVENTION 
Methods of making a rolling bearing race provided with a continuous rupture 
seam along at least one area of its periphery and having a seating surface 
and a race surface for rolling elements, the rolling seating race surface 
being exposed before rupture along at least a part of the intended course 
of the rupture seam to high-energy radiation which radiates transversely 
within local confines to the intended course of the rupture seam, and, 
during rupture, the area of the surface exposed to radiation is subjected 
to tensile load by an external force are known and are used for hardened 
rolling bearing races. These methods are based on the penetration of 
high-energy radiation to create locally within the texture of the rolling 
bearing race an extreme brittleness acting as a quasi "inner groove" along 
which the rolling bearing race is split by the influence of an external 
force which is especially small when acting on the rolling bearing race so 
that the area of its surface exposed to radiation is subjected to tensile 
load. Such a method is known (DE-OS No. 3,425,829, FIG. 1) and has been 
proven commercially. However, the occasional chipping off of material from 
the running surface during rupture along the rupture seam so that the 
respective bearing race became useless is a disadvantage thereof. 
OBJECTS OF THE INVENTION 
It is an object of the invention to provide a method of this type wherein a 
chipping off of material from the running surface in the area of the 
rupture seam during rupture is prevented. 
This and other objects and advantages of the invention will become obvious 
from the following detailed description. 
THE INVENTION 
The method of producing a rolling bearing race provided with a continuous 
rupture seam along at least one area of its periphery and having a seating 
surface and a raceway surface for rolling elements, the rolling bearing 
race surface being exposed before rupture along at least a portion of the 
intended course of the rupture seam to high-energy radiation with the 
local confines transverse to the intended course of the rupture seam and 
during rupture the surface area exposed to radiation is subjected to 
tensile stress by an external force is characterized in that the sealing 
surface (2,8) of the bearing race (1,7) is exposed to the radiation and 
the external force is exerted as a pressure force onto the raceway surface 
(3,9) along an area directly opposed to the area (6,10) of the seating 
surface (2,8) exposed to radiation. It has been shown that such a method 
prevents the described chipping off with high certainty, and best results 
are achieved when the line of impact of the pressure force extends 
precisely through the intended curve of the rupture seam. 
According to a feature of the invention, the high-energy radiation acted 
upon the seating surface is a laser beam or electron beam. 
In a modification of the invention, a method of making an outer rolling 
bearing race split at two diametrically opposed areas of its periphery 
provides that the seating surface is exposed to the radiation so that the 
depth of penetration of the radiation is at least 30 percent of the wall 
thickness of the bearing race. Advantageously, this results in the desired 
lemon shape of the split outer roller bearing races during rupture, i.e. 
both halves of the roller bearing race having a slightly increasing radius 
of curvature toward the rupture seams. In the assembled state of the 
roller bearing race, the occurrence of irregularities in the raceway 
surface in the area of the rupture seam and thus resulting disturbed run 
of the roller elements is prevented.

FIG. 1 shows an outer roller bearing race 1 having seating surface 2 and a 
raceway surface 3 which is to be split in two half shells by rupture along 
two diametrically opposed areas of its periphery. For that purpose, the 
outer roller bearing race 1 which is supported in a prism 4 and acted upon 
by a stamping tool 5 exerting an external force thereon for achieving the 
rupture is exposed along the intended course 6 of the rupture seam to a 
laser beam radiating within local confines transversely to the course 6 to 
create preferred points of fracture. 
While thus the seating surface 2 is exposed to the laser beam, the raceway 
surface 3 of the outer roller bearing race 1 is acted upon by the external 
force which is a pressure force exerted by the stamping tool 5. The outer 
roller bearing race 1 is aligned with the stamping tool 5 so that the 
pressure force is exerted on the raceway surface 3 at the area which is 
directly opposed to the area of the seating surface 2 exposed to radiation 
and thus subjected to tensile load during rupture. Then, the outer roller 
bearing race 1 is aligned in the prism 4 so that the other area of the 
bearing surface 2 i.e. in FIG. 1 the upper area exposed to the radiation, 
is split in the described manner. 
If the laser beam acts upon the bearing surface 2 of the outer roller 
bearing race 1 so that the depth of penetration of the laser radiation is 
at least 30 percent of the wall thickness of the roller bearing race 1 and 
the race is split in the described manner, minor plastic deformations are 
obtained in the area of the rupture seams resulting in a small increase of 
the radius of curvature of the obtained half shells toward the rupture 
seams so that the split outer roller bearing race 1 has the desired lemon 
shape. 
FIG. 2 illustrates an inner roller bearing race 7 having a seating surface 
8 and a raceway surface 9 and is to be provided with rupture seams along 
two diametrically opposed areas of its periphery. For that purpose, the 
seating surface 8 is exposed to a laser beam along the intended course 10 
of the rupture seams and the seating surface 8 of the inner roller bearing 
race 7 is supported by two posts 12 attached to a frame 11. A stamping 
tool 13 exerts a pressure force onto the raceway surface 9 of the roller 
bearing race 7. As shown in FIG. 2, the inner roller bearing race 7 is 
aligned with the stamping tool 13 so that the line of impact of the 
pressure force extends through the area of the seating surface 8 exposed 
to the laser beam so as to be subjected to tensile load by the pressure 
force during rupture. 
It should be noted that the bursting seam can be of any suitable shape. It 
may extend e.g. in the direction of the longitudinal axis or also be 
inclined to the latter and it may also be arc-shaped or arrow-shaped. 
Various modifications of the method of the invention may be made without 
departing from the spirit or scope thereof and it should be understood 
that the invention is intended to be limited only as defined in the 
appended claims.