JP6855974B2 - Rolling bearings and their manufacturing methods - Google Patents

Description

The present invention relates to rolling bearings, more particularly low dust generation rolling bearings. The present invention also relates to a method for producing the same.

Rolling bearings may be used, for example, in transport system devices arranged inside semiconductor manufacturing devices. Rolling bearings used in such a vacuum environment or in a clean atmosphere such as a clean room (hereinafter, may be referred to as "vacuum environment, etc.") have low operating smoothness, high durability, and the like. Dust generation is required. Conventionally, by applying and sealing a lubricant to the rolling part of a rolling bearing, wear of the rolling element and the part that comes into contact with the rolling element is prevented, and smooth operation is maintained, but contamination due to dust generation, etc. is maintained. In rolling bearings used in an almost unacceptable vacuum environment, etc., the amount of lubricant scattered or evaporated to the outside of the rolling bearing by using a fluorine-based lubricant based on a fluorine-based lubricating oil with extremely low volatility. Is suppressed.

Regarding such a fluorine-based lubricant, in Patent Documents 1 and 2, low dust generation and durability are improved by using a fluorine-based lubricant having a functional group having a high affinity with the bearing material in the molecular structure. ing. Further, Patent Document 3 discloses a fluorine-based grease containing a fluorine-based lubricating oil as a base oil and polytetrafluoroethylene as a thickener. Further, Patent Documents 4 and 5 show a rolling apparatus in which a fluorine-based grease is sealed. Further, Patent Document 6 discloses a rolling bearing coated with a fluorine-based solid lubricant mainly containing polytetrafluoroethylene.

Further, Patent Document 7 describes a rolling bearing in which a lubricating film having a lubricating oil containing a fluororesin and a lubricating oil having a ^{vapor pressure of 1 × 10 -5} Pa or less at 20 ° C. is formed by oil plating treatment. It is shown.

Japanese Unexamined Patent Publication No. 2001-173667 Japanese Unexamined Patent Publication No. 62-246621 Japanese Unexamined Patent Publication No. 1-284542 Japanese Unexamined Patent Publication No. 2003-13974 Japanese Unexamined Patent Publication No. 2002-357225 Japanese Unexamined Patent Publication No. 5-240257 Japanese Unexamined Patent Publication No. 2005-36959

However, in Patent Documents 1 and 2, low dust generation and durability are improved by adhering a fluorine-based lubricating oil having a functional group having a high affinity with the bearing material, but the bearing member is chemically chemically. The attached molecule is a single molecule layer, and other fluorine-based lubricating oils that are not chemically attached are not used for attachment. Further, in general, a fluorine-based lubricating oil having a functional group has a higher vapor pressure than a fluorine-based lubricating oil having no functional group, so that the fluorine-based lubricating oil that has not been subjected to adhesion evaporates to generate outgas or dust. Generated as particles.

As in Patent Document 7, the amount of the fluorine-based lubricant that is not attached can be reduced by the oil plating treatment, but there is room for improvement in the durability of the lubricating film.

Further, when fluorine-based grease is used as in Patent Documents 3 to 5, it is necessary to reduce the amount of grease used in order to suppress external scattering, but in this case, the lubricating action is insufficient or It is forced to reduce durability.

When the rolling portion is coated with a fluoropolymer solid lubricant as in Patent Document 6, the solid lubricant may be peeled or chipped or dust may be generated due to wear under a situation where a relatively large axial load is applied. Therefore, it may be insufficient in terms of durability and low dust generation.

The present invention has been made in view of the above-mentioned problems, and provides a rolling bearing which can be suitably used in a vacuum environment or the like, has less dust and outgas generated from the rolling bearing, and has excellent durability. The purpose is to do.

In order to solve the above problems, the present invention provides the following rolling bearings and a method for manufacturing the same.
(1) On at least one of the raceway surface of the inner and outer rings and the rolling surface of the rolling element,
A fluoropolymer having a vapor pressure of 1 × ^10-5 Pa or less at 38 ° C. and an average molecular weight of 6250 or less and a fluororesin having an average molecular weight of 3000 or less in terms of mass ratio. : Rolling bearing characterized by having a lubricating film made of a fluoropolymer contained in a ratio of fluororesin = 1: 0.40 to 1: 0.48.
(2) The rolling bearing according to (1) above, which is used in a vacuum or in a clean room.
(3) A fluoropolymer having a vapor pressure at 38 ° C. of 1 × ^10-5 Pa or less and an average molecular weight of 6250 or less and a fluororesin having an average molecular weight of 3000 or less are mixed in a mass ratio of fluorine. Lubricating oil: Fluororesin = 1: 0.40 to 1: 0.48 Fluoro-lubricating oil: Diluting solvent = 1: 12 ~ A method for manufacturing a rolling bearing, which comprises oil-plating at least one of the raceway surface of the inner and outer rings and the rolling surface of the rolling element by using a lubricant diluting solution mixed at 1:16.
(4) The method for manufacturing a rolling bearing according to (3) above, wherein after the oil plating treatment, the rolling bearing is heated at 100 ° C. or higher and 250 ° C. or lower for 15 minutes or longer and 60 minutes or shorter.

According to the present invention, it is possible to suppress dust generation and outgassing while maintaining a high degree of rotational performance by forming a lubricating film composed of a lubricant containing a specific fluoropolymer and a fluororesin. A rolling bearing that can be used and has excellent durability can be obtained.

It is a partially broken sectional view which shows an example of the rolling bearing of this invention. It is sectional drawing which shows the durability test apparatus. It is sectional drawing which shows the dust generation test apparatus. It is sectional drawing which shows the dynamic friction torque test apparatus. It is a graph which shows the result of the vacuum high temperature endurance test. It is a graph which shows the result of the dynamic friction test. It is a graph which shows the result when the ^{rotation speed is 300min -1} in the dust generation test. It is a graph which shows the result when the ^{rotation speed is 1000min -1} in the dust generation test. It is a graph which shows the result of the verification-1 of the compounding ratio of a fluorine-based lubricating oil in a lubricant diluted solution. It is a graph which shows the result of the verification-2 of the compounding ratio of a fluorine-based lubricating oil in a lubricant diluted solution.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

In the present invention, the type and structure of the rolling bearing are not limited, and a lubricating film made of a specific fluorine-based lubricant described later is formed on at least one of the raceway surface of the inner and outer rings and the rolling surface of the rolling element. ing. For example, as shown in FIG. 1, the rolling bearing 100 includes an inner ring 101, an outer ring 102, a ball 103 which is a rolling element, and a corrugated cage 104 manufactured by press working. A lubricating film 105 is formed on the raceway surface, the raceway surface of the outer ring 102, and the surface of the ball 103, respectively. The lubricating film 105 may be formed on any one of the raceway surface of the inner ring 101, the raceway surface of the outer ring 102, and the ball 103.

The material forming the inner ring 101, the outer ring 102, the ball 103, and the cage 104 is not limited, but is formed of a metal material generally used for bearings, for example, a metal material having corrosion resistance. To. Examples of this type of metal material include bearing steels such as JIS standard SUJ2, martensitic stainless steels such as JIS standard SUS440C, precipitation-hardened stainless steels such as JIS standard SUS630, and carburizing and nitriding treatments on these metal materials. Or, those which have been subjected to an appropriate hardening treatment such as a coating treatment of diamond-like carbon can be mentioned. For light load applications, for example, austenitic stainless steels such as JIS standards SUS304 and SUS316, and titanium alloys that have been surface-hardened can be used. In addition to the above metal materials, ceramics such as silicon nitride, alumina, and zirconia can be used for the ball 103.

Among the metal materials and ceramics listed above, it is preferable to use a material having corrosion resistance, in particular, martensitic stainless steel is used for the inner ring 101 and the outer ring 102, and martensitic stainless steel and ceramic are used for the ball 103. It is desirable to use it. The reason is as follows.

Usually, in order to give the rolling bearing corrosion resistance, a method of adding a rust preventive agent to the lubricant is adopted. However, since this rust inhibitor evaporates more easily than each component of the fluorine-based lubricant constituting the lubricating film 105 of the present invention, the addition of the rust inhibitor causes an increase in dust generation and outgassing. .. Therefore, if a corrosion-resistant material is used for the inner ring 101 and the outer ring 102, corrosion resistance is realized and it is not necessary to add a rust preventive agent, so that dust generation and outgassing, which are the objects of the present invention, can be suppressed. ..

In addition to the above metal materials, brass, titanium, and the like are preferably used for the cage 104, but synthetic resin materials can also be used. Examples of the synthetic resin material include fluororesins such as PTFE and ethylene tetrafluoroethylene (ETFE), engineering plastics such as polyetheretherketone (PEEK), polyphenylene sulfide (PPS), polyethersulfone (PES), and nylon 46. It is also possible to use plastic or the like. Reinforcing fibers such as glass fibers may be added to these synthetic resin materials. The type of the cage 104 may be a crown type or a punched type in addition to the corrugated type.

The lubricating film 105 contains a fluorine-based lubricating oil and a fluororesin. The fluorinated lubricating oil has a vapor pressure of 1 × 10 ^-5 Pa or less at 38 ° C., and the lower the vapor pressure, the smaller the outgas, which is preferable. If the vapor pressure at 38 ° C. ^{exceeds 1 × 10 -5} Pa, the effect of suppressing outgassing cannot be sufficiently obtained even if the fluororesin is added. Moreover, it is preferable that the average molecular weight is 6250 or less. When the average molecular weight exceeds 6250, the dynamic friction torque value of the rolling bearing becomes significantly large.

The fluorine-based lubricating oil is not limited as long as it satisfies the above vapor pressure and average molecular weight, and for example, a fluoropolyether polymer or a polyfluoroalkyl polymer can be used. The fluoropolyether _polymer, -C _{x -F} 2x -O- called general formula (X is an integer from 1 to 4) is a polymer containing units represented by the main repeating units.

The polyfluoroalkyl polymer is _{represented by the formula R 1} − (CF ₂ ) _{n −} R ₂ (n is an integer), and examples of R ₁ and R ₂ are represented by the following chemical formula 1. R ₁ and R ₂ may be the same or different.

Further, as the fluorine-based lubricating oil, in addition to the one having no functional group in the molecular structure, a certain amount of the one having a functional group in the molecular structure may be added. As the functional group, those having a high affinity for the metal, for example, an epoxy group, an amino group, a carboxyl group, a hydroxyl group, a mercapto group, a sulfone group or an ester group are preferable.

As the above-mentioned fluorine-based lubricating oil, more specifically, a mixture with perfluoropolyether (PFPE) or a derivative thereof, for example, Solvay Specialty Polymers Japan Co., Ltd. trade name FONBLIN Y standard, Fombulin emulsion (FE20, EM04, etc.) or FONBLIN Z derivatives (FONBLIN Z DEAL, FONBLIN Z DIAC, FONBLIN Z DISOC, FONBLIN Z DOL, FONBLIN Z DOLTX2000, FONBLIN Z TETRAOL, etc.) are preferably used.

Fluororesin has the function of trapping excess fluoropolymer that is not used for adhesion, and further enhances the effect of suppressing dust generation and outgassing. Therefore, the lubricating film 105 can be formed thick, and the durability can be improved.

As the fluororesin, for example, polytetrafluoroethylene (PTFE), fluorinated ethylene perfluorovinyl ether copolymer (PFA), fluorinated ethylene propylene copolymer (FEP), or the like can be used. Further, the fluororesin has an average molecular weight of 3000 or less.

Then, a fluorine-based lubricant in which the above-mentioned fluorine-based lubricating oil and the above-mentioned fluororesin are mixed is prepared.
The lubricating film 105 is formed by oil plating treatment. The blending ratio of the fluorine-based lubricating oil and the fluororesin in the fluorine-based lubricant is preferably a mass ratio of fluorine-based lubricating oil: fluorine resin = 1: 0.40 to 1: 0.48. If the content of the fluororesin is lower than the above-mentioned compounding ratio, the dust generation suppressing effect is deteriorated, and conversely, if the content is high, the content of the fluororesin-based lubricating oil is low, so that the lubrication performance is deteriorated. More preferably, the compounding ratio is 1: 0.43 to 1: 0.46.

Further, the fluororesin is a powder, and the fluorine-based lubricant is in the form of a so-called gel. The finer the fluororesin, the more preferable it is, and the average particle size is more preferably 1 μm or less.

Since the concentration of the fluorine-based lubricant is too high for the oil plating treatment, the lubricant diluted solution is prepared by diluting with a diluting solvent. The lubricant diluted solution preferably has a fluorine-based lubricating oil: diluted solvent = 1:12 to 1:16 in terms of mass ratio. If the amount of diluting solvent is less than this compounding ratio, the amount of fluorine-based lubricating oil may be excessive and low outgassing and low dust generation may be impaired. There is a possibility that the lubrication durability performance will be insufficient due to lack of oil. Desirably, the compounding ratio is fluorine-based lubricating oil: diluting solvent = 1: 13 to 1:15.

Diluting solvents include alternative fluorocarbon (PFC), fluorine-based inert solution "Novec" manufactured by 3M Japan Ltd., "Bertrel" manufactured by Mitsui Dupont Fluorochemical Co., Ltd., and Solvay Specialty Polymers Japan. Examples include "Galden" manufactured by Co., Ltd.

The lubricant diluting solution may be composed of only the above-mentioned fluoropolymer, fluororesin and diluting solvent, but in consideration of the chemical and mechanical properties of the lubricating film 105, further, the lubricant diluting solution Other components may be added in consideration of coatability. For example, a fluororesin having an average particle diameter of 1 μm and a fluororesin having an average particle diameter of 2.5 μm may be mixed.

Then, the inner ring 101, the outer ring 102, the ball 103, and the cage 104 are assembled to complete the rolling bearing 100, and after degreasing and cleaning, a lubricant diluting solution is applied between the inner ring 101 and the outer ring 102 where the ball 103 exists. Inject only the required amount with a dropper or the like. Then, by rotating the rolling bearing 100 several times, the lubricant diluting solution is adhered to the rolling portion and the sliding portion of the inner ring 101, the outer ring 102, the ball 103, and the cage 104. In addition to the dropper, the lubricant diluting solution may be applied by a brush or by spraying with a spray.

Further, the assembled rolling bearing 100 can be immersed in the storage tank of the lubricant diluting solution and then pulled up. In this dipping method, individual parts constituting the rolling bearing 100 may be individually immersed to form a lubricating film, and then the bearing may be assembled.

After that, the entire rolling bearing 100 to which the lubricant diluting solution is attached is heated at 100 ° C. or higher to 250.
The lubricating film 105 is formed by heating at ° C. or lower for 15 minutes or more and 60 minutes or less to evaporate the diluting solvent. If the heating temperature and the heating time exceed the upper limit temperature and the upper limit heating time, the lubricity of the lubricant constituting the lubricating film 105 deteriorates, and the raceway surfaces of the inner ring 101 and the outer ring 102 and the rolling of the ball 103 It causes a decrease in the hardness of the moving surface and a change in size. Conversely, if the temperature is set too low or the heating time is too short, the diluting solvent cannot be completely removed. Therefore, in the actual oil plating treatment, it is sufficient to remove the diluting solvent within the above heating temperature and heating time range and according to the type and content of the diluting solvent used. Set the heating temperature and heating time. In addition, considering the materials constituting the raceway surface and the like, for example, when quenching / tempering steel is used, the heating temperature and heating time are set so as not to cause the above-mentioned decrease in hardness and dimensional change.

As the rolling bearing of the present invention, for example, the following can be exemplified.

90% by mass of a fluorine-based lubricating oil having no functional group in its molecular structure and 10% by mass of a fluorine-based lubricating oil having a functional group in its molecular structure are mixed to obtain a fluorine-based lubricating oil. The vapor pressure of this fluorine-based lubricating oil at 38 ° C. is 1 × 10 ⁻⁵ Pa or less, and the average molecular weight is 6250 or less.

The above-mentioned fluorine-based lubricating oil and PTFE powder having an average molecular weight of 3000 or less and an average particle size of 1 μm are mixed in a mass ratio of fluorine-based lubricating oil: PTFE powder = 1: 0.42 to perform fluorine-based lubrication. Prepare the agent.

Next, the fluorine-based lubricant and the diluting solvent "Galden SV80" manufactured by Solvay Specialty Polymers Japan Co., Ltd. are diluted by mass ratio with a fluorine-based lubricant: diluting solvent = 1: 13, and the lubricant diluting solution is used. And.

Then, a deep groove ball bearing made of SUS440C is immersed in a diluted lubricant solution, and after pulling up, the surface of the inner and outer rings is wiped off, and the entire bearing is heated at 120 ° C. to 140 ° C. for about 30 minutes to form a lubricating film. Rolling bearing is completed.

In the rolling bearing 100 of the present invention, the lubricating action of the lubricating film 105 is stably maintained, and since the fluoropolymer has a low vapor pressure, it is difficult to volatilize, and the fluoropolymer that is not used for adhesion is fluorine. Since it is trapped by the resin, it produces low dust and low outgas. Further, unlike grease, the rotational resistance is extremely small, so that the torque does not increase and high-precision rotational performance can be obtained. Furthermore, since the fluidity is maintained, dust generation due to peeling, chipping, and wear seen in the solid lubricating film is suppressed. Therefore, the rolling bearing of the present invention is suitable for use in a vacuum or in a clean room such as a precision machine manufacturing factory.

Also in the manufacturing method, the lubricating film 105 can be made into a thin film by performing an oil plating treatment. When the lubricating film 105 becomes thick, excess lubricant is likely to be scattered, so that the effect of suppressing dust generation and outgas is reduced, but according to the present invention, there is no such problem.

The present invention will be further described below with reference to test examples, but the present invention is not limited thereto.

First, the test apparatus used for each test will be described.

(Durability test equipment)
FIG. 2 shows a durability test device. As shown in the figure, two test bearings 2 are loaded and fitted from both ends of the rotating shaft 1 in two step portions of the rotating shaft 1 arranged horizontally. .. A bearing housing 3 having a substantially sleeve shape is fitted to each of two test bearings 2, and the test bearing housing 3 has a step portion on the outer diameter so that the step portion is abutted. Are fitted to the portal housing 5, respectively. The two portal housings 5 are mechanically joined to the intermediate plate 16 of the vacuum chamber 7 and support the test bearing 2 so that the rotating shaft 1 is kept horizontal.

The test bearing 2 can be preloaded with a spring 6 (compression spring in the figure) or the like. A heater 4 is wound around the outer diameter of the bearing housing 3, and the temperature of the test bearing 2 can be raised as needed.

The test bearing 2 and the rotating shaft 1 supported by the portal housing 5 are all arranged inside the vacuum chamber 7. A coupling 9 is arranged at the end of the rotary shaft 1, and the rotary introduction shaft 10 coaxially connected to the coupling 9 is rotatable from the outside while maintaining vacuum airtightness with the vacuum chamber 7. It has become. An exhaust port 8 is vacuum-tightly connected to the bottom 7A of the vacuum chamber 7, and a vacuum pump can be connected and operated to the exhaust port 8 to create a vacuum environment inside the vacuum chamber 7.

For the vacuum airtightness of the rotary introduction shaft 10, a magnetic seal, a magnetic coupling, an elastic seal such as a differential exhaust seal or an O-ring can be used.

After operating the vacuum pump to create a vacuum environment inside the vacuum chamber 7, if the rotation introduction shaft 10 is rotated by an external drive (not shown), the test bearing 2 also rotates. Therefore, in the vacuum environment, the test bearing 2 also rotates. It is possible to perform a rotation test of.

At this time, if the heater 4 is energized and operated, the temperature of the test bearing 2 can be raised. If the temperature of the test bearing 2 is monitored by a sensor (thermoelectric pair or the like) (not shown), it is possible to perform a rotation test of the test bearing 2 in a vacuum environment at a predetermined bearing test temperature.

The materials of the rotating shaft 1, the bearing housing 3, and the portal housing 5 are not particularly limited, but general mild steel, austenite stainless steel such as SUS304, martensitic stainless steel such as SUS420, and ferritic stainless steel such as SUS430. Ferritic stainless steel, etc., precipitation-hardened stainless steel such as SUS630, etc. are used.

The material of the spring 6 may be a general piano wire, an oil tempered wire, or the like, but when the test is performed by raising the temperature, stainless steel such as SUS304 or SUS631 is used, and when the test is performed at 350 ° C. or higher, the spring 6 is used. It is preferable to use an alloy material having excellent heat resistance such as Inconel 600 or Inconel X-750.

The material of the coupling 9 is not particularly limited, and in addition to general aluminum alloys such as A5052 and A5056, duralumin such as A2017, A2024 and A7075, and stainless steel such as SUS316L, SUS304 and SUS303 are used alone or in combination. Used for. When the test bearing 2 is heated to perform the test, it is possible that the rotating shaft 1 thermally expands. Therefore, a coupling 9 having a sufficient allowable axial displacement that can absorb the thermal expansion length is selected. To. Although not shown, a ball coupling or the like in which a shaft, a cup covering the shaft, and both of them are mechanically coupled with a ball has a large allowable axial displacement, and is therefore suitable for raising the temperature of the test bearing 2.

Two support bearings 11 are arranged at equal distribution positions from the center point of the two test bearings 2 on the rotating shaft 1, and the support bearings 11 are fitted in a substantially cylindrical support bearing housing 12. A wire 13 is attached to a position corresponding to the center point of the outer diameter of the support bearing housing 12, and a weight tray 14 is attached to the other end of the wire 13. When the test bearing 2 is horizontally supported, the wire 13 is suspended from the central point of the two test bearings 2, and the weight tray 14 is suspended immediately below the wire 13. When the weight 15 is placed on the weight tray 14 and suspended, a radial load is applied to the two test bearings 2, but the rotating shaft is applied so that the load is evenly applied to each test bearing 2. 1 and the parts attached to it are set and arranged. The weight of the weight 15 is set so as to have a predetermined radial load in consideration of the weight of the rotating shaft 1 supported by the test bearing 2 and the parts attached thereto.

The material of the top plate 7B is austenitic stainless steel such as SUS304, SUS316, SUS316L, general aluminum alloys such as A5052 and A5056, duralumin such as A2017, A2024, and A7075, but glass is used. It may be possible to look inside the vacuum chamber 7. In addition to general soda glass, tempered glass, quartz glass, etc. are used as the glass material, and it can be said that using heat-resistant glass containing boron oxide is suitable for high-temperature bearing tests.

The portal housing 5 is fastened to the vacuum chamber intermediate plate 16 horizontally arranged at the center position in the depth direction of the vacuum chamber 7, at the intermediate point of the portal housing 5 on the vacuum chamber intermediate plate 16. A through hole 16A is provided, and the wire 13 is suspended through the center of the through hole 16A.

After loading the weight 15 on the weight tray 14 by inserting a hand from a maintenance port (not shown), the maintenance port is closed and the vacuum chamber 7 is vacuum-sealed.

Next, the functions and effects of this device will be described. Two test bearings 2 are inserted into the rotating shaft 1, the device is assembled according to a predetermined procedure, and the rotating shaft 1 is arranged horizontally by the two portal housings 5. The rotation shaft 1 is connected to the rotation introduction shaft 10 by a coupling 9 in a rotation restraint manner. The rotation introduction shaft 10 is vacuum-sealed so as to be externally rotatable.

Since the exhaust port 8 is provided through the bottom 7A of the vacuum chamber 7, the inside of the vacuum chamber 7 can be exhausted by connecting the exhaust port 8 to a vacuum pump (not shown) in a vacuum airtight manner.

When the vacuum pump is operated, the inside of the vacuum tank 7 becomes a vacuum environment. At this time, if the rotation introduction shaft 10 is rotated by an external drive mechanism (not shown), the rotation shaft 1 rotates and the test bearing 2 also rotates. Therefore, the test bearing 2 can be rotated in a vacuum environment.

When the heater 4 is energized, the bearing housing 3 around which the heater 4 is wound is heated, and the test bearing 2 fitted to the bearing housing 3 is heated. At this time, by controlling the heater 4 by arranging a temperature sensor such as a thermoelectric pair (not shown) in contact with the outer diameter of the test bearing 2, the test at a predetermined bearing temperature becomes possible.

A torque detector (not shown) is connected to the rotation introduction shaft 10 in a normal pressure environment, and the dynamic friction torque of the rotation introduction shaft 10 is constantly monitored during the test. If the test bearing 2 continues to operate and the test bearing 2 is damaged eventually, the dynamic friction torque value of the test bearing 2 will change, and as a result, the dynamic friction torque value of the rotary introduction shaft 10 will change. It is possible to detect the occurrence of damage to the test bearing 2. When the drive source of the rotation introduction shaft 10 is a servomotor or the like, by monitoring the change in the servo voltage output value of the motor, the change in the dynamic friction torque value by the torque detector can be detected without installing the torque detector. It can be replaced with monitoring.

If the dynamic friction torque value changes, or if the servo voltage output value changes, the test bearing 2 may have been damaged. Therefore, the test equipment is stopped, the test is completed, and the test bearing 2 runs. The distance (total number of revolutions) is used as an index of durability performance.

The device specifications are as follows.
・ Test bearing:
Inner diameter: 8-40 mm
Quantity: 2
Bearing posture: Horizontal axis Rotating wheel: Inner ring rotation
・ Rotation speed: Maximum 3000min ^-1
・ Test environment: Vacuum
・ Bearing temperature: Maximum 400 ℃
・ Measurement item: Dynamic friction torque value

(Dust generation test equipment)
FIG. 3 shows a dust generation test device. As shown in the figure, the center shaft 23 is coaxially fitted and fastened to the end portion 22A of the rotating shaft 22 horizontally supported by the two support bearings 21. ing. The test bearing 24 is coaxially fitted to the outer diameter of the center shaft 23, and the inner ring of the test bearing 24 is mechanically integrally attached to the center shaft 23 by the inner ring retainer 25. The outer ring of the test bearing 24 is coaxially fitted to the test bearing housing 26, and the test bearing housing 26 is arranged coaxially with the rotating shaft 22. The outer ring end face of the test bearing 24 is in contact with the end face of the outer ring retainer 27 all around, and a load is applied from the end face of the outer ring retainer 27 to the right side of the drawing by the compression spring 28, whereby the test bearing 24 is in a preloaded state. It is held in.

The coupling 29 is coaxially fitted to the end 22A of the rotating shaft 22 and mechanically integrally coupled, and the motor shaft 30A of the motor 30 shown only partially is coaxial on the opposite side of the coupling 29. Fitted together and mechanically integrally connected.

Therefore, if the motor 30 is rotationally driven, the rotating shaft 22 can be rotated to rotate the inner ring of the test bearing 24. The test bearing 24 rotates while maintaining the preload state.

The rotating shaft 22 penetrates the ring-shaped magnetic seal 31, and the outer diameter of the rotating shaft 22 and the magnetic seal 31 are hermetically sealed. Since all the parts mechanically connected to the outer diameter of the magnetic seal 31 are hermetically sealed by an O-ring to form an airtight chamber, the end portion 22A of the rotating shaft 22 is inside the airtight chamber 32 from the outside. It is inserted and at the same time airtightness is maintained.

Even if the rotating shaft 22 is rotated, the airtight chamber 32 is maintained in an airtight state by the function of the magnetic seal 31, so that the test bearing 24 is mechanically coupled to the end 22A of the rotating shaft 22 to form the airtight chamber 32. The test bearing 24 can be rotated internally. Since the inside of the airtight chamber 32 is maintained in an airtight state, even if dust is generated from the support bearing 21, the dust does not enter the airtight chamber 32.

The airtight chamber 32 includes a cylindrical airtight chamber body 33, and if the airtight chamber body 33 is made of a transparent member such as acrylic or glass, the test bearing 24 in the airtight chamber 32 can be visually observed.

A disk-shaped side plate 34 is airtightly connected to the end surface of the airtight chamber body 33. The side plate 34 is provided with two through holes, and the piping port 35 is airtightly coupled to each of the through holes. If clean air cleaned with a hepa filter or the like is piped and connected to one of the piping ports 35, and a particle counter (not shown) is piped and connected to the other, clean air is continuously introduced into the airtight chamber 32, and at the same time, air is introduced. Particle measurement can be performed on the air inside the closed room 32 with a particle counter. Since the clean air can be introduced into the airtight chamber 32 at the same time as the air is introduced into the particle counter by the pump built in the particle counter, all the particles measured by the particle counter are the particles generated inside the airtight chamber 32. It can be said that.

Therefore, if the test bearing 22 is rotated inside the airtight chamber 32, it can be said that all the measured particles are generated from the test bearing 24 because no other dust generation source exists inside the airtight chamber 32. Therefore, this device makes it possible to carry out a dust generation test of a bearing in a normal pressure environment.

The test specifications are as follows.
・ Test bearing:
Inner diameter: 8 to 60 mm
Quantity: 1
Bearing posture: Horizontal axis Rotating wheel: Inner ring rotation
・ Rotation speed: Maximum 3000min ^-1
・ Test environment: normal pressure
・ Bearing temperature: Normal temperature
・ Measurement items: Dust size and number

(Dynamic friction torque test device)
FIG. 4 shows the entire device configuration. FIG. 4 (1) is a side view and FIG. 4 (B) is a view taken along the arrow A. As shown, the rotating shaft 61 is horizontally supported by the support bearing 62, and one end of the rotating shaft 61 is coaxially coupled to the motor 64 by a coupling 63. The inner diameter of the test bearing 65 is coaxially fitted to the other end of the rotating shaft 61 with the rotating shaft 61. An outer cylinder 66 having a substantially U-shaped cross section is coaxially fitted to the test bearing 65. The outer cylinder 66 is formed so that the end surface of the outer cylinder 66 is arranged at a good squareness with the test bearing 65.

An air pad 67 is coaxially arranged on the end surface of the outer cylinder 66 so as to face the pad surface. When air is conducted through the air pad 67, air is ejected from the pad surface of the air pad 67 to press the end surface of the outer cylinder 66, so that an axial load can be applied to the test bearing 65 in a non-contact state.

Since the connecting shaft 68 is connected to the spherical seat at the center of the end surface opposite to the pad surface of the air pad 67, the air pad 67 can freely maintain its posture around the spherical seat. The connecting shaft 68 is connected to and supported by the load meter 69A. When the compression spring 70 in the vicinity of the load meter 69A is compressed, the load meter 69A advances by the load, and an axial load can be applied to the outer cylinder 66 via the air pad 67. A predetermined axial load can be applied to the test bearing 65 by conducting air to the air pad 67 and compressing the compression spring 70 while monitoring the load value output by the load meter 69A.

A pin 71 is arranged perpendicular to the outer diameter at a position corresponding to the test bearing 65 on the outer diameter of the outer cylinder 66. A thread 72 is connected to the pin 71, and the thread 72 is coaxially connected to the axis of another load meter 69B after being extended in the direction perpendicular to the paper surface. A pin 71, a load meter 69B, and the like are arranged so that the thread 72 is supported perpendicular to the paper surface, that is, in the tangential direction of the outer diameter of the test bearing 65.

Here, air is conducted to the air pad 67 to operate the air pad function, and a predetermined axial load is applied to the test bearing 65 via the outer cylinder 66. After that, when the motor 64 is energized and rotated at a predetermined rotation speed, the inner ring of the test bearing 65 rotates. As the inner ring rotates, the outer ring of the test bearing 65 also starts to rotate due to rolling friction, but since the outer cylinder 66 and the load meter 69B are connected by the thread 72, the load meter 69B becomes a detent. The inner ring of the test bearing 65 continues to rotate, and the outer ring is in a stationary state. The output value of the load meter 69B at this time is the rotating force of the test bearing 65.

If the radial dimension of the connection position between the pin 71 and the thread 72 is taken into consideration in the accompanying force, the dynamic friction torque value of the test bearing 65 at a predetermined rotational speed can be measured. The axial load applied to the test bearing 65 is the load value applied to the air pad, and the radial load applied to the test bearing 65 is the own weight of the outer cylinder 66. Due to the function of the air pad 67, no frictional force is applied to the outer cylinder 66 from the air pad 67.

In rolling bearings, in the case of unidirectional rotation, torque spikes may occur immediately after the start of rotation and show a large dynamic friction torque value, but the dynamic friction torque value begins to settle about 1 minute after the start of rotation, and then rolling familiarity progresses. Then, the dynamic friction torque value gradually decreases, and the value tends to settle down about 15 minutes after the start of rotation. Therefore, the dynamic friction torque characteristics of the test bearing 65 can be roughly known by measuring the dynamic friction torque values 1 minute and 15 minutes after the start of rotation.

The device specifications are as follows.
・ Test bearing inner diameter: 20 mm
Quantity: 1
Axial posture Horizontal / Rotation speed: Maximum 1000min ^-1
・ Rotation direction: One direction ・ Test environment: Normal pressure ・ Bearing temperature: Room temperature ・ Load condition: Axial load and radial load ・ Measurement time: 1 minute and 15 minutes after rotation start ・ Measurement item: Bearing rotation force

Various tests shown below were performed using each of the above test devices.

(Vacuum high temperature durability test)
The following test bearings of Example 1, Comparative Example 1-1, and Comparative Example 1-2 were prepared.
(Example 1)
Fluorine-based lubricating oil A having a steam pressure of 1 × ^10-5 Pa and an average molecular weight of 6250 at 38 ° C. and PTFE powder having an average molecular weight of 3000 and an average particle size of about 4 μm are mixed in terms of mass ratio of fluorine. Lubricating oil: PTFE powder = 1: Approximately 0.44 is mixed to prepare a fluorine-based lubricant A. Next, the fluorine-based lubricant A and the fluorine-based dilution solvent are diluted in a mass ratio of fluorine-based lubricant A: dilution solvent = 1: 14 to obtain a lubricant dilution solution A. Then, a deep groove ball bearing (inner diameter of 8 mm) made of SUS440C is immersed in the lubricant diluting solution A, and after pulling up, the surface of the inner and outer rings is wiped off, and the entire bearing is heated at 140 ° C. for about 30 minutes to form a lubricating film. A test bearing was manufactured. In addition, a press cage was attached to the test bearing.

(Comparative Example 1-1)
A lubricant-diluted solution in which a fluorine-based lubricating oil containing a fluorine-based lubricating oil B having an average molecular weight of 8400 as a main component and a fluorine-based dilution solvent are mixed in a mass ratio of fluorine-based lubricant B: dilution solvent = 1:19. A test bearing was produced in the same manner as in Example 1 except that B was used.

(Comparative Example 1-2)
According to JP-A-2005-36959, alkylated cyclopentane (steam pressure: 1 × ^10-5 Pa) is used as the lubricating oil C, and the lubricating oil containing this as the main component and the diluting solvent are mixed in a mass ratio with the lubricating oil. A test bearing was produced in the same manner as in Example 1 except that the lubricant diluting solution C in which C: diluting solvent = 1:19 was used.

In each test bearing, the space between the inner ring and the outer ring was exposed (without a shield).

Then, using the durability test apparatus shown in FIG. 2, the vacuum high temperature durability was compared under the following test conditions.
・ Rotation speed: 3000min ^-1
・ Test environment: Vacuum ( ^{about 1 x 10 -1} Pa)
・ Bearing temperature: 200 ° C
-Load condition: With preload (Load condition is radial load P / C <5 (*))
(* P: dynamic equivalent load, C: basic dynamic constant load)
・ Test end conditions: The dynamic friction torque value being monitored suddenly increases, abnormal noise, and a large amount of wear.
End of test when powder is generated or when they are combined ・ Number of tests: 1 time

The test results are shown in FIG. 5. Example 1 shows about 1.2 times more durability than Comparative Example 1-1 and about 1.4 times more durability than Comparative Example 1-2. As described above, it can be seen that the rolling bearing of the present invention is excellent in durability performance in a vacuum high temperature environment.

(Dynamic friction torque test)
Using a deep groove ball bearing having an inner diameter of 20 mm, a lubricating film by oil plating was formed in the same manner as in Example 1, Comparative Example 1-1 and Comparative Example 1-2 to prepare a test bearing. It should be noted that the case where the same test bearing as in Example 1 is used is the case where the same test bearing as in Example 2 and the case where the same test bearing as in Comparative Example 1-1 is used, and the case where the same test bearing as in Comparative Example 2-1 and Comparative Example 1-2 is used. Let's refer to the case of using Comparative Example 2-2.

Then, the dynamic friction torque values of each test bearing were compared using the dynamic friction torque test apparatus shown in FIG. The test conditions are as follows.
・ Rotation speed: 1000min ^-1
・ Test environment: Normal pressure ・ Bearing temperature: Normal temperature ・ Load condition: Axial load and radial load ・ Measurement time: 1 minute and 15 minutes after rotation start ・ Measurement item: Bearing rotation force

In Comparative Examples 2-1 and 2-2, the blending ratio of the lubricating oil and the diluting solvent is 1:19, which is larger than the blending ratio (1:12 to 1:16) specified in the present invention. .. Therefore, when the same oil plating treatment is performed, it is considered that the total weight of the lubricating oil adhering to the bearing is smaller in Comparative Examples 2-1 and 2-2. Since the amount of lubricating oil adhered is a factor that increases the dynamic friction torque value of the bearing, the dynamic friction torque value is usually larger in Comparative Examples 2-1 and 2-2 than in Example 2. As shown in 6, the test result shows that the dynamic friction torque value of Example 2 is smaller.

It is considered that the kinetic friction torque value increases as the amount of lubricating oil adhered increases. However, the mixing ratio of the amount of fluorine-based lubricating oil and the fluororesin is within the scope of the present invention, and the mixing ratio of the fluorine-based lubricant and the diluting solvent is also set. Within the range of the present invention, it is possible to prevent the dynamic friction torque value from becoming large and keep it at a small value without making the amount of the fluoropolymer-based lubricating oil extremely small.

As described above, if the oil plating treatment is performed with the blending ratio of the fluoropolymer and the fluororesin and the blending ratio of the fluorine-based lubricating oil and the diluting solvent within the range of the present invention, the amount of the fluoropolymer can be reduced. Rolling bearings with a small dynamic friction torque value can be used without being extremely reduced.

(Dust generation test)
As the test bearing, the above-mentioned Example 2, Comparative Example 2-1 and Comparative Example 2-2 were used. The case where the test bearing of Example 2 is used is compared with the case where the test bearing of Example 3, the case where the test bearing of Comparative Example 1-1 is used, and the case where the test bearing of Comparative Example 3-2 and Comparative Example 1-2 are used. Example 3-2.

Then, using the dust generation test apparatus shown in FIG. 3, the number of particles of 0.1 μm or less generated from each test bearing was counted, and the number of particles ^{per 1 ft 3} was compared. The test conditions are as follows.
Rotation speed: 2 Conditions and testing environment 300 min ^-1 and 1000min ^-1: normal pressure - bearing temperature: normal temperature and loading condition: preload only Measuring device: Particle Counter measured ^{flow: 0.25ft} 3 ^/2.5min , Multiply the number of measured particles to 1ft ³・ Number of measurements: 24 times

Figure 7 results in rotation speed 300 min ^-1, indicates the results of a rotational speed 1000min ^-1 in FIG. When the number of particles is 0, it is described as "1" for convenience.

As shown in FIG. 7, at a rotation speed of 300 min ^-1 , the number of Examples 3 is ^{0 to several per 1 ft 3} , whereas that of Comparative Example 3-1 is about 2000 and that of Comparative Example 3-2 is about 4000. is there. In terms of cleanliness class, Example 3 is cleanliness class 1, Comparative Example 3-1 is class 100, and Comparative Example 3-2 is class 1000.

Further, as shown in FIG. 8, in 1000 min ^-1 , the number of Examples 3 is about 0 to 10, whereas that of Comparative Example 3-1 is about 100,000 and that of Comparative Example 3-2 is about 600,000. is there. In terms of cleanliness class, Example 3 has a cleanliness class 1, Comparative Example 3-1 has a cleanliness class of 10000, and Comparative Example 3-2 has a cleanliness class of 100,000.

As described above, it can be seen that the test bearing of Example 3 according to the present invention is extremely excellent in particle characteristics. In Comparative Examples 3-1 and 3-2, the blending ratio of the lubricating oil and the diluting solvent was 1:19, and the dilution ratio was larger than the range of the present invention (1:12 to 1:16), and the same oil plating was performed. When the treatment is performed, the total weight of the lubricating oil adhering to the bearing is considered to be smaller in Comparative Examples 3-1 and 3-2. The smaller the amount of lubricating oil adhered, the smaller the number of particles generated from the bearing should be. Therefore, the number of particles in Comparative Examples 3-1 and 3-2 is usually smaller than that in Example 3. , As shown in FIGS. 7 and 8, the result of Example 3 is smaller.

As described above, if the oil plating treatment is performed with the blending ratio of the fluoropolymer and the fluororesin and the blending ratio of the fluorine-based lubricating oil and the diluting solvent within the range of the present invention, the amount of the fluorine-based lubricating oil can be reduced. A rolling bearing with a small number of generated particles can be obtained without extremely reducing the amount of particles.

(Verification of compounding ratio of fluorine-based lubricating oil in lubricant diluted solution-1)
A test bearing was produced by forming a lubricating film by oil plating using a deep groove ball bearing having an inner diameter of 20 mm in the same manner as in Example 1. The case where the same test bearing as in Example 1 is used is referred to as Example 4.

Further, the content (blending ratio) of the fluorine-based lubricating oil in the diluted lubricant solution was set to 1.7 times that of Example 4, and a lubricating film was formed by oil plating in the same manner as in Example 4 to prepare a test bearing. Then, it was referred to as Comparative Example 4-1. Further, a test bearing in which the content (blending ratio) of the fluorine-based lubricating oil in the diluted lubricant solution was 3.3 times that of Example 4 was designated as Comparative Example 4-2.

Then, the dynamic friction torque values of each test bearing were compared using the dynamic friction torque test apparatus shown in FIG. The test conditions are as follows.
・ Rotation speed: 1000min ^-1
・ Test environment: Normal pressure ・ Bearing temperature: Normal temperature ・ Load condition: Axial load and radial load ・ Measurement time: 1 minute and 15 minutes after rotation start ・ Measurement item: Bearing rotation force

The content (blending ratio) of the fluorinated lubricating oil in the diluted lubricant solution is 1.7 times in Comparative Example 4-1 and 3.3 times in Comparative Example 4-2 with respect to Example 4. Since a lubricating film is formed on all three test bearings by the same oil plating treatment, the amount of fluorine-based lubricating oil adhering to the bearings is approximately 1 in Comparative Example 4-1 assuming 1.0 in Example 4. 7.7, Comparative Example 4-2 is about 3.3.

The results are shown in FIG. 9 (the results of Example 4 are diverted from the results of Example 2), and the dynamic friction torque values increase in the order of the amount of fluorine-based lubricating oil adhered. That is, it can be seen that when the amount of the fluorine-based lubricating oil adhered is increased, the dynamic friction torque value increases accordingly. On the other hand, as shown in FIG. 6, in Example 2 (same as in Example 4), the dynamic friction torque value is smaller than that in Comparative Examples 2-1 and 2-2. That is, it can be said that the compounding ratio of the fluorine-based lubricating oil specified in the present invention is an appropriate amount in terms of the dynamic friction torque value of the rolling bearing. That is, by setting the blending ratio of the fluorine-based lubricating oil and the fluororesin within the range of the present invention and also setting the blending ratio of the fluorine-based lubricating oil and the diluting solvent within the range of the present invention, the amount of the fluorine-based lubricating oil can be extremely increased. It is possible to prevent the dynamic friction torque value from increasing and keep it at a small value without reducing it.

As described above, if the oil plating treatment is performed with the blending ratio of the fluoropolymer and the fluororesin and the blending ratio of the fluorine-based lubricating oil and the diluting solvent within the range of the present invention, the amount of the fluorine-based lubricating oil can be reduced. Rolling bearings with a small dynamic friction torque value can be used without being extremely reduced.

(Verification of compounding ratio of fluorine-based lubricating oil in lubricant diluted solution-2)
As the test bearing, the above-mentioned Example 4, Comparative Example 4-1 and Comparative Example 4-2 were used. The case where the test bearing of Example 4 is used is compared with the case where the test bearing of Example 5 is used, the case where the test bearing of Comparative Example 4-1 is used is compared with the case where the test bearing of Comparative Example 5-1 is used, and the case where the test bearing of Comparative Example 4-2 is used. Example 5-2.

Then, using the dust generation test apparatus shown in FIG. 3, the number of particles of 0.1 μm or less generated from each test bearing was counted, and the number of particles ^{per 1 ft 3} was compared. The test conditions are as follows.
・ Rotation speed: 1000min ^-1
· Test Environment: normal pressure - bearing temperature: normal temperature and loading condition: preload only Measuring device: Particle Counter measured ^{flow: 0.25ft} 3 ^/2.5min, converted-in 1 ft ³ by the measured particle count to four times Number of measurements: 24 times

The results are shown in FIG. 10 (the results of Example 5 are diverted from the results of ^{Example 3 at 1000 min -1).} When the number of particles is 0, it is described as "1" for convenience. Example 5 has about ^{0 to 10 pieces per 1ft 3} , whereas Comparative Example 5-1 has about 400 pieces, and Comparative Example 5-2 has about 4000 pieces. In terms of cleanliness class, Example 5 has a cleanliness class 1, Comparative Example 5-1 has a cleanliness class 100, and Comparative Example 5-2 has a cleanliness class 1000.

The content (blending ratio) of the fluorinated lubricating oil in the diluted lubricant solution is 1.7 times in Comparative Example 5-1 and 3.3 times in Comparative Example 5-2 with respect to Example 5. Since a lubricating film is formed on all three test bearings by the same oil plating treatment, the amount of fluorine-based lubricating oil adhering to the bearings is approximately 1 in Comparative Example 5-1 assuming that Example 5 is 1.0. 7.7, Comparative Example 5-2 is about 3.3.

As shown in FIG. 10, the number of particles increases in the order of the amount of the fluorine-based lubricating oil adhered. That is, it can be seen that as the amount of the foot-based lubricating oil adhered is increased, the number of particles is increased accordingly.

On the other hand, as shown in FIG. 5, Example 1 (same as Example 5) has higher durability under vacuum high temperature than Comparative Examples 1-1 and 1-2. That is, it can be said that the amount of the fluorine-based lubricating oil specified in the present invention is an appropriate amount in terms of the vacuum high temperature durability performance of the rolling bearing. That is, by setting the blending ratio of the fluorine-based lubricating oil and the fluororesin within the range of the present invention and the blending ratio of the fluorine-based lubricating oil and the diluting solvent within the range of the present invention, the amount of the fluorine-based lubricating oil is extremely high. It is possible to maintain a large vacuum high temperature durability performance by preventing the vacuum high temperature performance from becoming small without increasing the pressure.

As described above, if the oil plating treatment is performed with the blending ratio of the fluoropolymer and the fluororesin and the blending ratio of the fluorine-based lubricating oil and the diluting solvent within the range of the present invention, the amount of the fluorine-based lubricating oil can be reduced. Rolling bearings with a small dynamic friction torque value can be used without being extremely reduced.

1 Rotating shaft 2 Test bearing 3 Bearing housing 4 Heater 5 Gate type housing 6 Spring
7 Vacuum tank 7A Bottom 8 Exhaust port 9 Coupling 10 Rotational introduction shaft 11 Support bearing 12 Support bearing housing
13 wire 14 weight tray 15 weight
16 Intermediate plate 16A Through hole
21 Support bearing 22 Rotating shaft 22A End
23 Center axis
24 Test bearing 25 Inner ring retainer 26 Test bearing housing
27 Outer ring retainer 28 Compression spring 29 Coupling 30 Motor 30A Motor shaft
31 Magnetic seal 32 Airtight room
33 Airtight chamber body 34 Side plate
35 Piping port
61 Rotating shaft 62 Support bearing 63 Coupling 64 Motor 65 Test bearing 69A, 69B Load meter 70 Compression spring 71 Pin 72 Thread

Claims (4)

On at least one of the raceway surface of the inner and outer rings and the rolling surface of the rolling element,
A fluoropolymer having a vapor pressure of 1 × ^10-5 Pa or less at 38 ° C. and an average molecular weight of 6250 or less and a fluororesin having an average molecular weight of 3000 or less in terms of mass ratio. : Rolling bearing characterized by having a lubricating film made of a fluoropolymer contained in a ratio of fluororesin = 1: 0.40 to 1: 0.48. The rolling bearing according to claim 1, wherein the rolling bearing is used in a vacuum or in a clean room. A fluoropolymer having a vapor pressure of 1 × ^10-5 Pa or less at 38 ° C. and an average molecular weight of 6250 or less and a fluororesin having an average molecular weight of 3000 or less in terms of mass ratio. : Fluororesin = 1: 0.40 to 1: 0.48 Fluorine-based lubricant and diluting solvent in mass ratio, Fluororesin-based lubricating oil: Diluting solvent = 1: 12 to 1:16 A method for manufacturing a rolling bearing, which comprises oil-plating at least one of the raceway surface of the inner and outer rings and the rolling surface of the rolling element by using the lubricant diluting solution mixed in 1. The method for manufacturing a rolling bearing according to claim 3, further comprising heating at 100 ° C. or higher and 250 ° C. or lower for 15 minutes or longer and 60 minutes or lower after the oil plating treatment.

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