The present disclosure relates to a self-lubricated rolling element cage used in steering column bearings and polymer based oil impregnated lubricant for rolling element bearings.
BACKGROUND
The background information herein below relates to the present disclosure but is not necessarily prior art.
Conventionally, there is no cage to retain the rolling elements for steering column bearings. The issues related to the existing steering column bearing are: misplacement of the rolling elements during assembly as there is no cage to retain the rolling elements, and degradation of the bearing performance due to contaminants that can cause abrasive failure. Re-lubrication methods are not practical to solve these issues and require maintenance.
Further, conventional rolling element bearings are lubricated using grease in sealed environment that tends to increase the torque. The quantity of grease used in conventional bearings is restricted and high quantity of grease leads to excessive heat generation due to over churning effect, which affects the performance of the bearings.
There is, therefore, felt a need to provide a better lubrication system for steering column bearing and rolling element bearings for long life and better bearing performance.
OBJECTS
Some of the objects of the present disclosure, which at least one embodiment herein satisfies, are as follows:
It is an object of the present disclosure to ameliorate one or more problems of the prior art or to at least provide a useful alternative.
An object of the present disclosure is to provide a process for manufacturing self-lubricated rolling element cage.
Another object of the present disclosure is to provide a process for manufacturing self-lubricated rolling element cage that ensures continuous lubricant flow.

Still another object of the present disclosure is to provide a polymer based oil impregnated lubricant for rolling element bearings.
Yet another object of the present disclosure is to provide a process for manufacturing self-lubricated rolling element cage and bearings that ensures minimum oil loss.
Other objects and advantages of the present disclosure will be more apparent from the following description, which is not intended to limit the scope of the present disclosure.
SUMMARY
In one aspect, the present disclosure provides a process for manufacturing a self-lubricated rolling element cage for steering column bearings. The process comprises the following steps.
Lubrication oil; polymer powder; and a coloring agent are mixed to obtain a mixture, followed by de-moisturizing to obtain a de-moisturized mixture. The de-moisturized mixture is filled in a bearing cavity defined between an inner ring and outer ring with rolling elements disposed therein, which is further mold pressed at a predetermined pressure in the range of 100-150 kgf/cm to obtain a mold. The mold is cured at a predetermined temperature in the range of 160-220°C for a predetermined time in the range of 2-8 minutes. The cured mold is then cooled at a predetermined rate in the range of 5°C/min to 40°C/min to open the mold, followed by flash trimming to obtain the self-lubricated cage for rolling elements.
In another aspect, the present disclosure provides a composition for self-lubricated rolling element cage for steering column bearings comprising lubrication oil in the range of 64 wt.% to 80 wt.%; polymer powder in the range of 17 wt.% to 34 wt.%; and a coloring agent in the range of 0.5 wt.% to 3 wt.% of the total composition.
In yet another aspect, the present disclosure provides a polymer based oil impregnated lubricant for rolling element bearing. The heat treated assembled rolling element bearings can be kept inside a die containing polymer oil lubricant. The self lubricant solution can be filled in between the ball gaps and ball-cage gaps. The tight packed solution can be compressed with a pressure in the range of 100-150 kgf/cm and cured with a temperature of 160-220 °C for 2 hours. Further, the die is cooled using forced air circulation.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING

A process for manufacturing of self-lubricating rolling element cage, of the present disclosure, will now be described with the help of the accompanying drawing, in which:
Figure 1 illustrates a self-lubricated rolling element cage;
Figure 2 illustrates a ball bearing filled with oil impregnated polyer resin; and
Figure 3 illustrates a microscopic view of the rolling element cage surface showing micro-pores.
DETAILED DESCRIPTION
Embodiments, of the present disclosure, will now be described with reference to the accompanying drawing.
Embodiments are provided so as to thoroughly and fully convey the scope of the present disclosure to the person skilled in the art. Numerous details are set forth, relating to specific components, and methods, to provide a complete understanding of embodiments of the present disclosure. It will be apparent to the person skilled in the art that the details provided in the embodiments should not be construed to limit the scope of the present disclosure. In some embodiments, well-known processes, well-known apparatus structures, and well-known techniques are not described in detail.
The terminology used, in the present disclosure, is only for the purpose of explaining a particular embodiment and such terminology shall not be considered to limit the scope of the present disclosure. As used in the present disclosure, the forms "a," "an," and "the" may be intended to include the plural forms as well, unless the context clearly suggests otherwise. The terms "comprises," "comprising," "including," and "having," are open ended transitional phrases and therefore specify the presence of stated features, integers, steps, operations, elements, modules, units and/or components, but do not forbid the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The particular order of steps disclosed in the method and process of the present disclosure is not to be construed as necessarily requiring their performance as described or illustrated. It is also to be understood that additional or alternative steps may be employed.
The terms first, second, third, etc., should not be construed to limit the scope of the present disclosure as the aforementioned terms may be only used to distinguish one element, component, region, layer or section from another component, region, layer or section. Terms

such as first, second, third etc., when used herein do not imply a specific sequence or order unless clearly suggested by the present disclosure.
The present disclosure envisages a process for manufacturing of self-lubricated rolling element cage and a composition for manufacturing the self-lubricated rolling element cage for steering column bearings for ensuring smooth flow of the lubricating oil to the rollers and bearings thereby minimizing oil loss.
In a first aspect, the present disclosure provides a process for manufacturing the self-lubricated rolling element cage. The process comprises the steps of mixing the lubrication oil, polymer powder and coloring agent to obtain a mixture followed by vacuum de-moisturizing the mixture. The de-moisturized mixture is filled in a bearing cavity defined between an inner ring and outer ring with rolling elements disposed therein followed by mold pressing at a predetermined pressure to obtain a mold. The mold is subjected to curing at a predetermined temperature for a predetermined time. The cured mold is further cooled at a predetermined rate followed by flash trimming to obtain the self-lubricated rolling element cage.
In accordance with the present disclosure, the predetermined pressure during the mold pressing is in the range of 100-150 kgf/cm .
In accordance with the embodiments of the present disclosure, the predetermined temperature for curing is in the range of 160-220°C for a predetermined time in the range of 2-8 minutes..
In accordance with the embodiments of the present disclosure, the predetermined rate for cooling is in the range of 5°C/min to 40°C/min to open the mold.
In accordance with the embodiments of the present disclosure, the self-lubricated rolling elements are spheres and rollers.
In a second aspect, the present disclosure provides a self-lubricated rolling element cage composition comprising lubrication oil in the range of 64 wt.% to 80 wt.%; polymer powder in the range of 17 wt.% to 34 wt.%; and a coloring agent in the range of 0.5 wt.% to 3 wt.% of the total composition.
In accordance with one embodiments of the present disclosure, the amount of polymer powder is 26.34 wt.% of the total composition.

In accordance with one embodiments of the present disclosure, the amount of coloring agent is 0.51 wt.% of the total composition.
In accordance with one embodiments of the present disclosure, the amount of lubrication oil is 73.15 wt.% of the total composition.
5 In accordance with one embodiments of the present disclosure, the lubrication oil is
polyalphaolefin based synthetic oil.
In accordance with one embodiment of the present disclosure, the polymer powder is ultrahigh molecular weight polyethylene (UHMWPE) and similar grade polymers.
A self lubricated rolling elemet cage as shown in figure 1 is typically having a plurality of
10 rolling elements rotatably embedded within a plurality of pockets in an annular ring of oil
impregnated polymer resin. The pockets are uniformly spaced about the periphery of the rolling element cage.
In accordance with one embodiment of the present disclosure, an oil impregnated polymer
resin can be used as a lubricating oil in ball bearings to ensure continuous lubrication as
15 shown in figure 2.
It is observed that the self-lubricated rolling element cage manufactured by the process and
composition of the present disclosure is capable of holding the lubricating oil for efficient
lubrication of rolling bearings. The self-lubricated rolling element cage surface consists of
pores structure with millions of micro-pores as shown in figure 3 to hold the lubricating oil.
20 The pores of the self-lubricated rolling element cage are so small that the lubricating oil is
retained in the material by surface tension, oozing from the surface of the self-lubricated rolling element cage along with the rotation of the bearings, which ensures lubricating action for a long period of time thereby minimizing the average loss of oil as compared to the conventional sealed bearing where grease is used as a lubricating medium.
25 The foregoing description of the embodiments has been provided for purposes of illustration
and not intended to limit the scope of the present disclosure. Individual components of a particular embodiment are generally not limited to that particular embodiment, but, are interchangeable. Such variations are not to be regarded as a departure from the present disclosure, and all such modifications are considered to be within the scope of the present
30 disclosure.
6

The present disclosure is further described in light of the following experiments which are set forth for illustration purpose only and not to be construed for limiting the scope of the disclosure. The following experiments can be scaled up to industrial/commercial scale and the results obtained can be extrapolated to industrial scale.
5 Example: Manufacturing of self-lubricated rolling element cage
Polyalphaolefin based lubricating oil (73.15 wt.%) having base oil viscosity of 150 cSt based
on the application was added to ultrahigh molecular weight polyethylene (26.34 wt.%) with
an average molecular weight 4.26 g/mol and sodium polysulfide aluminosilicate (0.51 wt.%)
to obtain a mixture. The mixture was de-moisturized and filled in a bearing cavity defined
10 between an inner ring and outer ring with rolling elements disposed therein. The de-
moisturized mixture was then mold pressed at a pressure of 120 kgf/cm2 to obtain a mold. The mold was cured at a temperature of 180°C for 4 minutes. The cured mold was further subjected to cooling at a rate of 15°C/min followed by flash trimming to obtain a self-lubricated rolling elements cage for steering column bearings.
15 The self-lubricated rolling element cage manufactured was tested as per the mentioned
oscillation cycle as provided in table 1 and test schematic for oscillation test is provided in table 2:
Table 1.

Test cycles
Dynamic Load Rating (Cr) 10.9 kN (1111.11 kgf)
Applied Axial Load, Fa (45% of Cr) 500 Kgf
Oscillation time for completing 1 cycle (1 cycle includes oscillation from 0°-180° and back to 180°-0°) 3.3 seconds
Target Duration 100,000 cycles for 2 sets 300,000 cycles for 4 sets 500,000 cycles for 2 sets
Temperature Ambient
Acceptance Criteria No breakage of ball cage assembly and net weight loss should be < 50 mg
7

Table 2.

S No. No. of cycles Bearings Weight loss comparison

Loss of oil (mg)
1 100000 Bearing 1 -22.425

Bearing 2

2 300000 Bearing 3 -29.045

Bearing 4

3 300000 Bearing 5 -22.955

Bearing 6

4 500000 Bearing 7 -38.790
It can be observed from table 2 that the rolling element cage manufactured by using the
process and composition of the present disclosure shows average weight loss of less than 50
5 mg.
The self-lubricated rolling element bearing manufactured was tested for reduction of noise value and torque as provided in table 3 and 4.
Table 3.

Noise bands High band (LG-Log Scale) Low Band (LG-Log Scale)
Sealed bearing (Conventional) 71 64
Polymer based oil impregnated self-lubricated rolling element bearing 66 58
10 Table 4.

Starting Torque comparison (Kgf. mm)
Sealed bearing (Conventional) 5.65
Polymer based oil impregnated self-lubricated rolling element bearing 2.70
8

It is observed from table 3 and table 4 that the self-lubricated rolling element bearing shows reduction in the noise bands and torque bands as compared to the conventional sealed bearings.
TECHNICAL ADVANCEMENTS
5 The present disclosure described herein above has several technical advantages including, but not limited to, the realization of:
- a process for manufacturing of self-lubricated rolling element cage;
- a composition for self-lubricated rolling element cage;
- a rolling element cage with smooth lubrication;
10 - a rolling element cage ensuring minimum oil loss; and
- a polymer based oil impregnated lubricant for rolling element bearings.
The embodiments herein and the various features and advantageous details thereof are explained with reference to the non-limiting embodiments in the following description. Descriptions of well-known components and processing techniques are omitted so as to not 15 unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
20 The foregoing description of the specific embodiments so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed
25 embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize
9

that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.
The use of the expression "at least" or "at least one" suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the disclosure to achieve one or more of the desired objects or results.
Any discussion of documents, acts, materials, devices, articles or the like that has been included in this specification is solely for the purpose of providing a context for the disclosure. It is not to be taken as an admission that any or all of these matters form a part of the prior art base or were common general knowledge in the field relevant to the disclosure as it existed anywhere before the priority date of this application.
The numerical values mentioned for the various physical parameters, dimensions or quantities are only approximations and it is envisaged that the values higher/lower than the numerical values assigned to the parameters, dimensions or quantities fall within the scope of the disclosure, unless there is a statement in the specification specific to the contrary.
While considerable emphasis has been placed herein on the components and component parts of the preferred embodiments, it will be appreciated that many embodiments can be made and that many changes can be made in the preferred embodiments without departing from the principles of the disclosure. These and other changes in the preferred embodiment as well as other embodiments of the disclosure will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the disclosure and not as a limitation.

WE CLAIM:

A process for manufacturing a self-lubricated rolling element cage for steering column bearings, said process comprising the following steps:
a) mixing lubrication oil; polymer powder; and a coloring agent to obtain a mixture;
b) vacuum de-moisturizing said mixture to obtain a de-moisturized mixture;
c) filling said de-moisturized mixture in a bearing cavity defined between an inner ring and outer ring with rolling elements disposed therein;
d) mold pressing said bearing cavity at a predetermined pressure to obtain a mold;
e) curing said mold at a predetermined temperature for a predetermined time to obtain a cured mold; and
f) cooling said cured mold at a predetermined rate followed by flash trimming to obtain said rolling element cage steering column.
The process as claimed in claim 1, wherein said predetermined pressure in step (d) is in the range of 100-150 kgf/cm .
The process as claimed in claim 1, wherein said predetermined temperature in step (e) is in the range of 160-220°C.
The process as claimed in claim 1, wherein said predetermined time in step (e) is in the range of 2-8 minutes.
The process as claimed in claim 1, wherein said predetermined rate in step (f) is in the range of 5°C/min to 40°C/min.
The process as claimed in claim 1, wherein said rolling elements are spheres and rollers.
A composition for manufacturing a self-lubricated rolling element cage for steering column bearings, said composition comprising lubrication oil in the range of 64 wt.%

to 80 wt.%; polymer powder in the range of 17 wt.% to 34 wt.%; and coloring agent in the range of 0.5 wt.% to 3 wt.% of the total composition.
The composition as claimed in claim 7, wherein the amount of said polymer powder is 26.34 wt.% of the total composition.
The composition as claimed in claim 7, wherein the amount of said coloring agent is 0.51 wt.% of the total composition.
The composition as claimed in claim 7, wherein the amount of said lubrication oil is 73.15 wt.% of the total composition.
The composition as claimed in claim 7, wherein said lubrication oil is synthetic based oil.
The composition as claimed in claim 7 or 11, wherein said lubrication oil is polyalphaolefin.
The composition as claimed in claim 7 or 8, wherein said polymer powder is ultrahigh molecular weight polyethylene (UHMWPE) powder.
The composition as claimed in claim 7 or 9, wherein said coloring agent is sodium polysulfide aluminosilicate.
A self lubricated rolling elemet cage comprising a plurality of rolling elements rotatably embedded within pockets in an annular ring of oil impregnated polymer resin, wherein said pockets are uniformly spaced about the periphery of said cage.