Thrust bearing

A cage and roller assembly in a hardened thrust bearing race is restrained within the race by heating a plurality of circumferentially widely separated parts of the race lip to soften the lip parts and bending the softened parts over the cage of the cage and roller assembly. An apparatus for assembling the thrust bearing includes a pair of electrodes located to apply a current through the lip to soften the lip and a form punch which is constructed to bend the softened part of the lip over a cage and roller assembly to an acute angle with repect to the rest of the lip.

This invention relates to thrust bearings. More particularly this invention 
is a new thrust bearing race, method of making a thrust bearing, and 
apparatus for making a thrust bearing. 
Three currently manufactured thrust bearings which have means for retaining 
a cage and roller assembly within a thrust bearing race are known as 
formed tabs, full 360.degree.curl and banding. The U.S. Pat. 3,900,235 
dated Aug. 19, 1975 to Richard L. Alling et al and entitled "TAB RACE" 
describes a thrust bearing with a race having formed tabs to retain the 
cage and roller assembly. The U.S. Pat. 3,913,994 dated Oct. 21, 1975 to 
Richard Alling et al and entitled "BEARING OFFSET LIP CAGE" describes, 
among other things, a full 360.degree. curl for retaining the cage and 
roller assembly. The U.S. Pat. 4,174,138 dated Nov. 13, 1979to Dean E. 
Johnston and entitled "THRUST BEARING AND SEATOR" describes a thrust 
bearing including a band for retaining the cage and roller assembly. 
Several problems are associated with the formed tab. The press tooling is 
complex and must be run slowly. The tooling requires a good deal of 
maintenance. The dimensions of the tabs are difficult to maintain. 
Improper tabs can result in poor retention, interference with the bearing 
performance, or damage to the bearing when it is being assembled. These 
problems, when combined, result in a relatively high scrap rate. 
The problems associated with the full 360.degree. curl are the same as the 
formed tab, however, the dimensional tolerances are not quite as tight. 
The problems associated with the banded assemblies include the high cost 
of manufacturing one or two additional components, the added inventory, 
and assembly problems. 
Our new thrust bearing race and new thrust bearing, method of making a 
thrust bearing, and apparatus for making a thrust bearing reduces costs 
and scrap. 
With this invention, the tight dimensional tolerances required with formed 
tabs are not required. The additional component or components required for 
a banded assembly are eliminated. The complex tooling required to make 
formed tabs and a full 360.degree. curl is not needed. 
Briefly described, the thrust bearing race has a radially extending annular 
raceway between inner and outer peripheries. An integral annular lip 
having an inside surface and an outside surface extends axially from at 
least one. At least one stake has one surface protruding from and the 
other surface indented from corresponding surfaces of the lip at an acute 
angle with respect to said lip surfaces. 
Briefly described, the new method of making a thrust bearing comprises 
placing a cage and roller assembly in a hardened thrust bearing race. The 
race has an axially extending lip. The cage has a portion extending 
radially to adjacent the inside of the lip, with the lip extending axially 
beyond the cage portion. A small axial and circumferential part of the lip 
is heated and softened. The softened part is bent to restrain the cage and 
roller assembly in the race. The stake may be bent over the cage of a cage 
and roller assembly or bent over another thrust race containing a cage and 
roller assembly to form a thrust bearing. 
Briefly described, the apparatus for assembling the thrust bearing includes 
electrodes located to apply a current through an axial and circumferential 
part of the lip of a thrust race to soften a predetermined part of the 
free end of the lip. A form punch is used to bend the softened part of the 
lip to an acute angle with respect to the rest of the lip. The lip extends 
axially beyond the cage and roller assembly or a second thrust bearing 
race.

In the various figures, like parts are referred to by like numbers. 
Referring to the drawings, and more particularly to FIG. 1, and FIG. 2, a 
thrust bearing is shown with a thrust bearing race 10 having a radially 
extending annular raceway 12, with a bore 14 for receiving a shaft (not 
shown). 
A totally solid integral annular lip 18 extends axially from the outer 
periphery of the raceway. At least one, and preferably three, 
circumferentially widely spaced stakes 20, are provided at the free end of 
the lip 18. In the embodiment shown, the stakes 20 are arcuately spaced 
apart about 120.degree.. 
Referring to FIG. 2, it can be seen that the lip 18 has an annular inside 
surface 22 and an annular outside surface 24. Each stake 20 has an inside 
surface 26 extending inwardly toward the axis of the race at an acute 
angle with respect to the inside surface 22 of the lip 18 and an outside 
surface 28 indented inwardly toward the axis of the race at an acute angle 
with respect to the outside surface 24 of the lip 18. The stakes 20 are 
used to restrain axial movement of a cage and roller assembly. The cage 30 
has circumferentially separated pockets 32 which circumferentially 
separate rollers 34. The cage 30 has an annular radially extending portion 
36 which extends to adjacent the inside surface 22 of the lip 18. The lip 
18 extends from the raceway 12 over and beyond the cage portion 36. The 
inside diameter of each stake 20 is less than the diameter of portion 36 
of cage 30 so that the cage and roller assembly is retained in the 
hardened race 10. 
For some applications, the thrust race and cage and roller assembly of FIG. 
2 may be used as a thrust bearing without the second race 42 opposed to 
the race 10. 
FIG. 3 and FIG. 4 illustrate an apparatus and method for making a thrust 
bearing assembly. The cage and roller assembly including the cage 30 
having a radially extending portion 36 extending to adjacent the lip 18 is 
placed in the hardened race 10. The opposed race 42 has a radially 
extending raceway 44 which is opposed to the radially extending raceway 12 
of race 10. The race 42 also has an integral lip 46 which extends axially 
from the inner diameter of raceway 44. 
Our new method of forming a thrust bearing includes the steps of assembling 
the bearing and then heating a small axial and circumferential area of the 
lip 18 to be able to form the stake 20 while it is still hot. It is 
necessary to form the stake while the area is hot since the raceways are 
hardened. Several methods of heating the small area of the lip before 
forming the stakes include, for example, resistance heating, induction 
heating, and laser heating. Resistance heating is shown in FIG. 3 and FIG. 
4. An electrode 50 is brought into contact with the free edge of the lip 
18. The other electrode 52 has a larger contact area with the thrust race 
10 and contacts the race in the area that is not to be heated. Therefore, 
electrode 52 serves as a heat sink. After the area of the lip to be heated 
is hot, the electrode 50 is retracted and the form punch 53 is moved 
inwardly toward the heated area to form the stake 20 (see FIG. 4). 
The electrodes 50 and 52 are located so that a current may be applied 
through an axial and circumferential portion of the lip 18 to soften a 
predetermined part of the lip which extends from the free end of the lip. 
The form punch 53 has an angled surface 54 for bending the softened part 
of the lip to the acute angle with respect to the rest of the lip. 
Thus, the stakes serve to restrain the cage and roller assembly in the 
thrust bearing. 
The electrodes are dimensioned to apply the current only over a small 
circumferential and axial portion of the lip to soften this small portion. 
For example, looking at FIG. 1, it can be seen that the stakes 20 only 
extend over a small part of the 360.degree. surface of the lip 18. Also, 
of course, the angled surface 54 of the form punch 53 is dimensioned so 
that the softened part of the lip is the only part which is bent over. 
Three groups of electrodes and form punch may be used to form the three 
stakes 20 simultaneously. Alternatively, one group of electrodes and form 
punch may be used and the bearing may be rotated to make the stakes 
sequential. 
By staking the bearing after it has been assembled, the tight dimensional 
tolerances required on the formed tab is reduced. Also, the additional 
band, or components, required for the banded thrust bearing assembly is 
not necessary. The complex tooling required for making the formed tabs in 
a formed tab bearing and the full 360.degree. curl in the 360.degree. curl 
bearing are not required. 
Note that a separate punch 53 is used to form the stakes, from the 
electrodes 50 and 52 to soften the lip portion. This allows the electrode 
to be manufactured from a good electrode material and allows the form 
punch 53 to be manufactured from a good punch material. Often good 
electrode material does not make good punch material and vice versa. By 
separating the two, the electrode and punch lives are greatly improved 
because compromises do not have to be made during the material selection. 
In the embodiment of FIG. 5, a second thrust bearing race 60 having a 
raceway 62 opposed to the raceway 12 of thrust bearing race 10 has an 
axially extending inner annular lip 64. The annular lip 64 extends axially 
from the inner periphery of the raceway 62. At least one and preferably 
three circumferentially spaced apart stakes 66 have an inside surface 68 
and an outside surface 70, which are in indented from and protrude from 
the inside surface 72 and outside surface 74, respectively of the lip 64 
away from the axis of the race at an acute angle with respect to the lip. 
The cage has an inner periphery 76 of less diameter than the outside 
diameter of the stake 66. Therefore, axial movement of the cage and roller 
assembly is restrained by the stake 66. 
In the bearing embodiment of FIG. 5, axial movement of the cage and roller 
assembly in one axial direction is restrained by contact of the portion 36 
of the cage with the stake 20 on hardened thrust race 10; axial movement 
of the cage and roller assembly in the other axial direction is restrained 
by contact of the portion 76 of the cage with the stake 66. 
In the thrust bearing embodiment of FIG. 6, the hardened thrust bearing 
race 80 has an axially extending outer lip 82 which is somewhat longer 
than the axially extending outer lip of the other embodiments so that the 
stake 84 may extend over the outer periphery of the opposed thrust race 60 
rather than over the cage of the cage and roller assembly. The thrust race 
60 extends radially to adjacent the inside surface 86 of the annular lip 
82. The annular lip 82 extends axially over and beyond the outer periphery 
88 of the thrust race 60. Inner surface 90 and outer surface 92 of the 
stake 84 are integral with and extend axially at an acute angle toward the 
axis of the bearing from inner surface 86 and outer surface 94, 
respectively of the annular lip 82. 
Axial movement of the cage and roller assembly and the thrust race 60 in 
one axial direction is restrained by contact of the outer periphery 88 of 
thrust race 60 with the stake 84; and axial movement of the cage and 
roller assembly and thrust race 80 in the other axial direction is 
restrained by contact of the inner periphery 96 of the cage and roller 
assembly with the stake 70 on the inner lip 64 of the thrust bearing race 
60. 
If desired, the inner annular lip of the race 60 could be made longer and 
rather than staking the thrust bearing race 60 over the cage and roller 
assembly, the thrust bearing race 60 could be staked over the inner 
periphery of the thrust bearing race 80. 
FIG. 7 and FIG. 8 illustrate an apparatus and method for making a thrust 
bearing assembly with the annular axially extending inner lip of the race 
60 staked over the cage inner periphery 76. The cage and roller assembly 
including the cage has a radially extending portion 76 extending to 
adjacent the outside of the lip 64. The cage and roller assembly has been 
placed in the hardened race 60. A second race 100 opposed to the race 60 
is provided. The opposed race 100 has a radially extending raceway 102 
which is opposed to the radially extending raceway 62 of race 60. The race 
100 also has an integral lip 104 which extends axially from the outer 
diameter of the raceway 102. As with the heating of an outer annular lip 
on a thrust bearing, several methods of heating the inner annular lip of 
the thrust bearing of the embodiment of FIG. 7 and FIG. 8 may be used. 
This includes resistance heating, induction heating, and laser heating. 
Resistance heating is shown in FIG. 7 and FIG. 8. The electrode 50 is 
brought into contact with the free edge of the lip 64. The other electrode 
106 has a larger contact area with the thrust race 60 and contacts the 
race in the area that is not to be heated. Therefore, electrode 106 serves 
as a heat sink. After the area of the lip to be heated is hot, the 
electrode 50 is retracted and the form punch 108 is moved outwardly at an 
angle toward the heated area to form the stake 66 (see FIG. 8). 
The axis of the form punch 108 is at an angle of approximately 45.degree. 
with respect to the axis of the bearing. Thus, the face 110 of the form 
punch is angled with respect to the inner annular lip 64 of the thrust 
race 60.