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Sept. 26, 1961 E. R. Lamson Et Al 3,001,838
LUBRICATED ANTI-FRICTION BEARINGS Original Filed April 16. 1958 2 Sheets-Sheet l
Sept. 26, 1961 E. R. Lamson Etal 3,001,838
LUBRICATED ANTI-FRICTION BEARINGS Original Filed April 16, 1958 2 Sheets-Sheet 2
LUBRICATED ANTI-FRICTION BEARINGS Edward R. Lamson, Greentree Road, Box 88, R.R. 4, Sewell, N.J., and Martin J. Devine, 2560 Prescolt Road, Havertown, Pa. Original application Apr. 16, 1958, Ser. No. 729,041, now Patent No. 2,978,793, dated Apr. 11, 1961. Divided and this application Oct. 28, 1958, Ser. No. 770,241
8 Claims. (Ci. 308—18S) (Granted under Title 35, U.S. Code (1952), sec. 266)
The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalities thereon or therefor.
This is a divisional application of copending application, Serial Number 729,041, filed April 16, 1958, now Patent No. 2,978,793.
The invention relates to lubricated anti-friction bearings and to a method of lubricating anti-friction bearings with bonded film lubricants. More particularly, the inventoin relates to high speed and high temperature antifriction bearings such as ball bearings having solid or dry-type lubricants tightly affixed or bonded to the components thereof and to a method of lubricating high speed and high temperature anti-friction bearings by affixing dry-type lubricants to treated and selected surfaces of the unassembled components of the bearings.
Prior attempts to lubricate high speed and high temperature anti-friction bearings with both wet-type lubricants such as greases and bonded film lubricants utilizing a dry-type lubricant or lubricants have been universally unsuccessful. It is well known that grease-type lubricants provide excellent lubrication for anti-friction bearings operated under conditions of relatively low speed and low temperature but have several inherent disadvantages when the bearings are operated under other conditions. For example, at high temperatures, greases become less viscous and have a tendency to seep or leak from a bearing, this loss due to seepage or leakage eventually and many times very quickly resulting in a failure of the greases to provide a film of lubricant between the friction or coacting surfaces of the bearing components. Conversely, at low temperatures, greases substantially increase in viscosity and materially add to the frictional drag or operating torque of a bearing. When greases are used at high temperatures coupled with a high vacuum, the greases vaporize and evaporate and thus deprive the bearing of the needed lubrication. It is also well known that greases deteriorate rapidly when exposed to certain types of nuclear radiation and chemical attack, this deterioration not only resulting in a failure to provide the necessary lubrication but also resulting in a damaging exposure of the bearing components to the harmful effects of the radiation and the corrosive action inherent in the chemical attack.
Bonded film lubricants, on the other hand, utilizing a dry-type lubricant such as a mixture of molybdenum disulphide and graphite as the lubricating constituent of the bonded film, possess none of the inherent disadvantages of the wet-type lubricants, but nevertheless, have never heretofore been successfully employed as a lubricating medium for high speed and high temperature antifriction bearings. This failure to successfully lubricate bearings of this type with bonded film lubrication has resulted primarily from the failure to develop a method or technique whereby a bonded film lubricant having a substantially uniform predetermined thickness could be rigidly or tenaciously affixed to either all of the components of an anti-friction bearing, selected components of an anti-friction bearing, or selected surfaces of selected components of an anti-friction bearing. A bonded film of substantially uniform thickness is extremely important
in the lubrication of high speed and high temperature anti-friction bearings due to the critical tolerances between the friction surfaces of the bearing components. A bonded film which is not substantially uniform in
5 thickness will interfere with the proper relative movement between the components of the bearing and thus produce undesirable frictional forces and heat which will result in a cracking or failure of the bonded film. Bonding or affixing a lubricant to selected components only or to
10 selected surfaces of selected components of an antifriction bearing is also an important factor in the successful utilization of bonded film lubricants from the standpoint of the use or the environmental application of the bearing. In many environment applications, it has been
15 found desirable and advantageous not to affix a lubricant to all of the components or to all of the surfaces of the components of an anti-friction bearing.
Accordingly, one of the objects of the present invention is to lubricate an anti-friction bearing with a bonded
20 film lubricant.
Another object of the invention is to provide an antifriction bearing with a bonded film lubricant of substantially uniform thickness on the components of the bearing.
25 Another object of the invention is to provide an antifriction bearing with a bonded film lubricant of substantially uniform thickness on selected components or on selected surfaces of selected components of the bearing. Another object of the invention is to provide an anti30 friction bearing the external surfaces of the components of which are roughened and carry a bonded film lubricant.
Another object of the invention is to provide an antifriction bearing having selected surfaces of selected components thereof which are roughened and carry a bonded 35 film lubricant.
Another object of the invention is to provide a lubricated anti-friction bearing having a substantially uniform operating torque over the entire operating temperature range of the lubricant. 40 Another object of the invention is to provide a method of lubricating an anti-friction bearing with a bonded film lubricant having a substantially uniform thickness.
Another object of the invention is to provide a method of lubricating an anti-friction bearing wherein all of the components or selected components only of the bearing are roughened and lubricated with a bonded film lubricant having a substantially uniform thickness.
Another object of the invention is to provide a method of lubricating an anti-friction bearing wherein only selected surfaces of selected components of the bearing are. roughened and lubricated with a bonded film lubricant having a substantially uniform thickness.
In conformity with these objects, the preferred embodiment of the invention is characterized by a high speed and high temperature ball bearing having rough or roughened external surfaces on the components thereof with a comminuted dry-type lubricant bonded or affixed to all of the roughened external surfaces by a bonding agent comprised of a hardened thermosetting resin. The comminuted lubricant is uniformly dispersed in the bonding agent and the bearing components are completely surrounded or enveloped by a lubricating film having a substantially uniform thickness.
The preferred method envisioned by the invention for lubricating an anti-friction bearing such as a 'high speed and high temperature ball bearing includes the steps of preparing or surface-treating all of the components of the bearing in an unassembled state to form roughened external surfaces thereon, coating the roughened and un„q assembled bearing components with a dry-type or solid comminuted lubricant suspended in a thermosetting bonding agent, heating the coated components to harden the
bonding agent, and then reassembling the lubricated components into an operative unit to provide an antifriction bearing having a bonded film lubricant on the friction surfaces thereof. The surface treatment of the bearing components resides in exposing the components 5 to an agent or means capable of producing roughened or microscopically irregular surfaces thereon which serve to anchor the bonded film. The coating must, of necessity, be applied in a manner to provide a lubricating film of substantially uniform thickness, and the selection of 10 the exact constituents for the coating mixture will be determined mainly by the conditions under which the bearing is expected to operate or perform.
These and other objects of the present invention will become readily apparent from the following description 15 taken in connection with the accompanying drawings, wherein:
FIG. 1 is a side elevation of a ball bearing illustrating a preferred embodiment of the invention;
FIG. 2 is an enlarged section taken along the line 20 II—II of FIG. 1;
FIG. 3 is a side elevation of a ball bearing illustrating another embodiment of the invention;
FIG. 4 is an enlarged section taken along the line IV—IV of FIG. 3; 25
FIG. 5 is a side elevation of a ball bearing illustrating another embodiment of the invention;
FIG. 6 is an enlarged section taken along line VI—VI of FIG. 5;
FIG. 7 is a side elevation illustrating another embodi- 30 ment of the invention; and
FIG. 8 is a section taken along the line VIII—VIII of FIG. 7.
Referring more particularly to the drawings wherein like structural details and components are designated by 35 like reference numerals, FIGS. 1 and 2 show an antifriction bearing 8 of the ball-type having components including an inner ring or race means 10 provided with a circumferentially extending groove or raceway 12 in the outer periphery 14 thereof and an outer ring or race 40 means 16 provided with a circumferentially extending groove or raceway 18 in the inner periphery 29 thereof. A plurality of substantially spherical rolling elements or balls 22, in this instance ten in number, are carried in the raceways 12 and 18 and, due to a predetermined curvature 45 of the raceways 12 and 18, are confined therein for rotary movement in a substantially circular orbit between the inner and outer race means 10 and 16, respectively. Being substantially spherical, balls 22 are also capable of independent rotary movement about their own geometrical axes and thus are capable of rotation both relative to themselves and to the inner and outer race means 10 and 16. A predetermined clearance or tolerance (not shown in the drawings) between the balls 22 and the raceways 12 and 18 permits the balls 22 to roll freely over the surfaces of the raceways.
A separator or cage means 24 is carried by the balls 22 and serves to space the balls 22 a uniform or equal distance apart in order to equalize any load that may be applied to the balls 22 through the races 10 and 16. 60 The cage means 24 is provided with a plurality, in this instance ten, of pockets or the like 26 therein (FIG. 1) each of which (FIG. 2) is adapted to receive a ball 22. The inner periphery of each pocket 26 is provided with a predetermined curvature and is adapted to be carried 65 on and thus frictionally engage the peripheral surface of its received ball 22.
The components of the anti-friction bearing 8 in this preferred embodiment of the invention are made of steel but may be made of any other material suitable for bear- ^ ing use such as iron, stainless steel, etc. Various alloys of steel and stainless steel have been found to be particularly satisfactory materials for use in the construction of high speed and high temperature anti-friction bearings. Inasmuch as the structure and function of ball-type anti- ^
friction bearings as well as the materials utilized in the construction thereof are well known in the art and per se form no part of the present invention, further discussion thereof is deemed unnecessary. Suffice it to say that in the use or environment application of the bearing 8, the inner race means 10 is adapted to receive a shaft or the like (not shown) which when rotated will also rotate the inner race means 10 and thereby impart rotation to the balls 22.
As best seen in FIG. 2, all of the components 10, 16, 22 and 24 of bearing 8 have roughened or microscopically irregular external surfaces 28 thereon and the roughened surfaces carry a lubricating film or coating 30 which completely surrounds or envelops each of the bearing components and is tightly affixed or bonded thereto. The roughened surfaces 28 on the bearing components provide receptive and tenaciously adhering inner bearing surfaces for the lubricating film 30 and in effect provide a positive anchoring means or mechanical interlock between the coating 30 and the bearing components. Roughened external surfaces 28 need have no particular "grade," "fineness ratio" or configuration and any suitable means or process may be utilized to effect the desired surface roughness or irregularity. Processes such as "phosphatizing," acid etching and mechanical abrading have been found to provide extremely desirable results, it being appreciated of course that these processes do not constitute a limitation on the article or lubricated bearing of the present invention and are merely cited as illustrations. A process suitable for use in roughening the external surfaces of anti-friction bearings are hereinafter discussed in greater detail in connection with the Method of Lubricating AntiFriction Bearings.
Constituent-v/ise, the film lubricant 28 is comprised of a solid comminuted lubricant uniformly dispersed in a cured thermosetting bonding agent. In this preferred embodiment of the invention, the bonded film 30 is comprised of a mixture of finely pulverized molybdenum disulphide and graphite dispersed in a cured phenolic resin, the pulverized lubricant being mixed in a substantially 9:1 ratio by weight with 9 parts of molybdenum disulphide to 1 part of graphite. While the constituents utilized in this preferred embodiment have been found to provide a satisfactory lubricating film, it will be appreciated of course that these constituents are merely illustrative of the invention and are not to be construed in a limiting sense. The selection of the particular constituents comprising the bended film is strictly a matter of choice and may include any other suitable dry-type comminuted lubricant or lubricants such as boron nitride, tungsten disulphide, or the like in combination with other suitable thermosetting bonding agents such as formaldehyde resins, silicone resins and vinyl resins. Suffice it to say, however, that the thermosetting agent selected should be capable of forming a tight bond that does not crack or "flake-off" in use and should be resistant to the deleterious effects of heat and pressure and to the action of hydrocarbons such as greases, oils and the like.
The mixture of comminuted molybdenum disulphide and graphite utilized as the lubricant in the preferred embodiment of the invention is a 5 micron grade although the size of the graphite particles is not critical. It has been found, however, that a solid comminuted lubricant having a particle size not greater than 7 microns provides a better lubricating action than a lubricant of larger particle size. The smaller size lubricant particles have a tendency to become more evenly dispersed in the thermosetting bonding agent and thus provide a more effective distribution of the lubricant.
It will also be appreciated that the dry-type lubricant of the bonded film may be comprised of single comminuted lubricant such as molybdenum disulphide only instead of a mixture of two lubricants ox furthermore may be comprised of a mixture of more.than two lubricants. If it is desired to use more than one comminuted lubricant in the