JP2019027545A - Rolling bearing and manufacturing method thereof - Google Patents

Abstract

To provide a rolling bearing capable of being suitably used under, for example, vacuum environment, having small dust and outgas occurring from the rolling bearing, and having excellent durability.SOLUTION: A rolling bearing has a lubrication film comprising a fluorine lubricant, wherein the fluorine lubricant contains, on at least one of raceway surfaces of inner and outer rings and a rolling surface of a rolling body, a fluorine lubrication oil whose steam pressure at 38°C is not larger than 1×10Pa and average molecular weight is not larger than 6250, and a fluorine resin whose average molecular weight is not larger than 3000, at a mass ratio of fluorine lubrication oil:fluorine resin=1:0.40 to 1:0.48.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a rolling bearing, and more particularly to a rolling bearing with low dust generation. The present invention also relates to a manufacturing method thereof.

  Rolling bearings may be used in, for example, a transfer system device disposed inside a semiconductor manufacturing apparatus. Rolling bearings used in such a vacuum environment or in a clean atmosphere such as a clean room (hereinafter sometimes referred to as “vacuum environment etc.”) have a low operating performance in addition to smooth operation and high durability. Dust generation is required. Conventionally, by applying and encapsulating a lubricant to the rolling part of a rolling bearing, the wear of the rolling element and the part that contacts the rolling element is prevented and the smooth operation is maintained. In rolling bearings that are used in a vacuum environment that is almost unacceptable, the amount of lubricant that scatters or evaporates outside the rolling bearing by using a fluorine-based lubricant based on a fluorine-based lubricating oil with extremely low volatility. Is suppressed.

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

Further, Patent Document 7 discloses a rolling bearing in which a lubricating film made of a lubricant containing a lubricating oil having a vapor pressure of 1 × 10 ⁻⁵ Pa or less at 20 ° C. and a fluororesin is formed by oil plating. It is shown.

JP 2001-173667 A JP-A-62-246621 JP-A-1-284542 JP 2003-13974 A JP 2002-357225 A Japanese Patent Laid-Open No. 5-240257 JP 2005-36959 A

  However, in Patent Documents 1 and 2, low dust generation and durability are improved by attaching a fluorine-based lubricating oil having a functional group having a high affinity with the bearing material. The adhering molecule is a monomolecular layer, and other fluorine-based lubricating oils not chemically attached are not used for adhesion. In general, fluorine-based lubricants having functional groups have higher vapor pressure than fluorine-based lubricants not having functional groups, so that fluorine-based lubricants that have not been attached evaporate, causing outgas and dust generation. Occurs as particles.

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

  In addition, as in Patent Documents 3 to 5, when fluorine-based grease is used, it is necessary to reduce the amount of grease used in order to suppress external scattering. The durability will be reduced.

  When a rolling part is coated with a fluorine-based polymer solid lubricant as in Patent Document 6, in a situation where a relatively large axial load is applied, the solid lubricant is peeled off or missing, or dust is generated due to wear. Therefore, it may be insufficient in terms of durability and low dust generation.

  The present invention has been made in view of the above-described problems, and provides a rolling bearing that 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-described problems, the present invention provides the following rolling bearing and a manufacturing method thereof.
(1) At least one of the raceway surface of the inner and outer rings and the rolling surface of the rolling element,
A fluorine-based lubricating oil 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 in terms of mass ratio. : A rolling bearing having a lubricating film made of a fluorine-based lubricant contained in a ratio of fluororesin = 1: 0.40 to 1: 0.48.
(2) The rolling bearing according to (1), which is used in a vacuum or in a clean room.
(3) A fluorine-containing lubricating oil 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 in terms of mass ratio. Lubricant: Fluorine Resin = 1: 0.40 to 1: 0.48 Fluorine Lubricant and Diluent Solvent in a Mass Ratio, Fluorine Lubricant: Diluent Solvent = 1: 12 A method for manufacturing a rolling bearing, characterized in that at least one of the raceway surfaces of the inner and outer rings and the rolling surface of the rolling element is subjected to oil plating using a diluted lubricant solution mixed at 1:16.
(4) The method for manufacturing a rolling bearing according to (3), wherein after the oil plating treatment, heating is performed at 100 ° C. to 250 ° C. for 15 minutes to 60 minutes.

  According to the present invention, by forming a lubricating film composed of a lubricant containing a specific fluorine-based lubricating oil and a fluororesin, it is possible to suppress dust generation and outgas while maintaining high rotational performance. In addition, a rolling bearing having 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 an endurance test apparatus. It is sectional drawing which shows a dust generation test apparatus. It is sectional drawing which shows a dynamic friction torque test apparatus. It is a graph which shows the result of a vacuum high temperature endurance test. It is a graph which shows the result of a dynamic friction test. In a dust generation test, it is a graph which shows a result when it is set as rotational speed 300min- ¹ . In a dust generation test, it is a graph which shows a result when it is set as rotational speed 1000min- ¹ . It is a graph which shows the result of the verification-1 of the compounding ratio of the fluorine-type lubricating oil in a lubricant dilution solution. It is a graph which shows the result of the verification-2 of the compounding ratio of the fluorine-type lubricating oil in a lubricant dilution solution.

  Embodiments of the present invention will be described below 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 surfaces of the inner and outer rings and the rolling surface of the rolling elements. ing. For example, as shown in FIG. 1, the rolling bearing 100 includes an inner ring 101, an outer ring 102, a ball 103 that is a rolling element, and a corrugated cage 104 that is manufactured by press working. Lubricating films 105 are respectively formed on the raceway surface, the raceway surface of the outer ring 102, and the surface of the ball 103. 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.

  There is no limitation on the material forming the inner ring 101, the outer ring 102, the ball 103, and the cage 104, but it is formed of a metal material generally used for bearings, for example, a metal material having corrosion resistance. The This type of metal material includes bearing steel such as JIS standard SUJ2, martensitic stainless steel such as JIS standard SUS440C, precipitation hardening stainless steel such as JIS standard SUS630, and carburizing and nitriding treatments for these metal materials. And those subjected to an appropriate curing treatment such as a diamond-like carbon coating treatment. For light load applications, for example, austenitic stainless steel such as JIS standard SUS304 or SUS316, or a titanium alloy subjected to surface hardening treatment can be used. Note that the balls 103 can be made of ceramic such as silicon nitride, alumina, or zirconia in addition to the above metal materials.

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

  Usually, in order to give corrosion resistance to the rolling bearing, a method of adding a rust preventive to the lubricant is taken. However, since this rust preventive agent tends to evaporate as compared with the respective components of the fluorine-based lubricant constituting the lubricating film 105 of the present invention, the addition of the rust preventive agent causes a generation of dust and outgas. . Therefore, if a corrosion-resistant material is used for the inner ring 101 and the outer ring 102, the corrosion resistance is realized, and it is not necessary to add a rust preventive agent. Therefore, it is possible to achieve the suppression of dust generation and outgas which is the object of the present invention. .

  The cage 104 is preferably made of brass, titanium, or the like, in addition to the above metal material, but may be made of a synthetic resin material. As this synthetic resin material, for example, fluorine resin such as PTFE, ethylene tetrafluoroethylene (ETFE), engineering such as polyether ether ketone (PEEK), polyphenylene sulfide (PPS), polyether sulfone (PES), nylon 46, etc. Plastics can also be used. These synthetic resin materials may contain reinforcing fibers such as glass fibers. The form of the cage 104 may be a coronal shape or a hollow shape in addition to the corrugated shape.

The lubricating film 105 contains a fluorine-based lubricating oil and a fluororesin. The fluorine-based lubricating oil has a vapor pressure of 1 × 10 ⁻⁵ Pa or less at 38 ° C., and the lower the vapor pressure, the less outgas 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 a fluororesin is added. Moreover, it is preferable that an average molecular weight is 6250 or less. When the average molecular weight exceeds 6250, the dynamic friction torque value of the rolling bearing is remarkably increased.

The fluorine-based lubricating oil is not limited as long as it satisfies the above-described 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 include those represented by the following chemical formula 1. R ₁ and R ₂ may be the same or different.

  In addition to the fluorine-based lubricating oil having no functional group in the molecular structure, a certain amount of one having a functional group in the molecular structure may be added. As this functional group, those having a high affinity for metals, 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.

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

  The fluororesin has an action of trapping excess fluorine-based lubricating oil that is not used for adhesion, and further enhances the effect of suppressing dust generation and outgas. Therefore, the lubricating film 105 can be formed thick, and durability can be improved.

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

And preparing the fluorine-type lubricant which mixed the said fluorine-type lubricating oil and the said fluororesin,
The lubricating film 105 is formed by oil plating. The blending ratio of the fluorinated lubricant and the fluororesin in the fluorinated lubricant is preferably a mass ratio of fluorinated lubricant: fluororesin = 1: 0.40 to 1: 0.48. When the content of the fluororesin is lower than the above blending ratio, the dust generation suppressing effect is deteriorated. On the other hand, when the content is high, the content of the fluorolubricating oil is reduced, so that the lubricating performance is deteriorated. More preferably, the blending ratio is 1: 0.43 to 1: 0.46.

  The fluororesin is a powder, and the fluorine-based lubricant is in a so-called gel form. The fluororesin is preferably as fine as possible, and more preferably 1 μm or less in average particle size.

  In order to perform oil plating, since the concentration of the fluorine-based lubricant is too high, a diluted lubricant solution is prepared by diluting with a diluent solvent. The lubricant diluted solution is preferably in a mass ratio of fluorinated lubricating oil: diluted solvent = 1: 12 to 1:16. If the dilution solvent is less than this compounding ratio, the amount of fluorine lubricating oil may be excessive, which may impair the low outgassing and low dust generation properties. Oil shortage may result in insufficient lubrication durability performance. Desirably, the blending ratio is fluorinated lubricating oil: diluting solvent = 1: 13 to 1:15.

  Diluting solvents include alternative chlorofluorocarbon-based diluting solvent, perfluorocarbon (PFC), fluorine-based inert solution "Novec" manufactured by 3M Japan Co., Ltd., "Bertrel" manufactured by Mitsui DuPont Fluoro Chemical Co., Ltd., Solvay Specialty Polymers Japan Examples include “Galden” manufactured by Co., Ltd.

  The lubricant diluted solution may be composed only of the above-mentioned fluorine-based lubricating oil, fluororesin and diluted solvent. However, in consideration of the chemical and mechanical properties as the lubricant film 105, the lubricant diluted solution In consideration of applicability, other components may be added. 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, after assembling the inner ring 101, the outer ring 102, the ball 103, and the cage 104 to complete the rolling bearing 100, after degreasing and washing, a lubricant diluted solution is applied to the place where the ball 103 exists between the inner ring 101 and the outer ring 102. Inject only the required amount with a dropper. Thereafter, the rolling bearing 100 is rotated several times so that the lubricant diluted solution adheres to the rolling part and the sliding part of the inner ring 101, the outer ring 102, the ball 103 and the cage 104. The supply of the diluted lubricant solution may be performed by brushing in addition to the dropper, or may be performed by spraying using a spray.

  In addition, the assembled rolling bearing 100 can be pulled up after being immersed in a storage tank for the diluted lubricant solution. In this dipping method, the individual parts constituting the rolling bearing 100 may be individually dipped to form a lubricating film, and then the bearing may be assembled.

Thereafter, the entire rolling bearing 100 to which the lubricant diluted solution is adhered is heated at 100 ° C. or higher and 250 ° C.
The lubricating film 105 is formed by heating at 15 ° C. or lower for 15 minutes to 60 minutes to evaporate the diluted solvent. When the upper limit temperature and the upper limit heating time are exceeded in the heating temperature and the heating time, the lubricity of the lubricant constituting the lubricating film 105 is deteriorated, and the raceway surfaces of the inner ring 101 and the outer ring 102 and the rolling of the balls 103 are deteriorated. It causes a decrease in the hardness of the moving surface and a dimensional change. Conversely, if the temperature is set too low or the heating time is short, the diluting solvent cannot be completely removed. Therefore, during the actual oil plating treatment, it is within the range of the above heating temperature and heating time, and is sufficient to remove the dilution solvent according to the type and content of the dilution solvent used. Set proper heating temperature and heating time. In consideration of the material constituting the raceway and the like, for example, when steel that has been quenched and tempered is used, the heating temperature and the heating time are set so as not to cause the above-described decrease in hardness and dimensional change.

  Examples of the rolling bearing of the present invention include the following.

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

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

  Next, a diluted lubricant solution is prepared by diluting the fluorine-based lubricant and “Galden SV80” manufactured by Solvay Specialty Polymers Japan Co., Ltd., which is a diluent solvent, with a fluorine-based lubricant: diluting solvent = 1: 13. And

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

  In the rolling bearing 100 according to the present invention, the lubricating action by the lubricating film 105 is stably maintained, and the fluorine-based lubricating oil is less likely to volatilize due to the low vapor pressure. Since it is trapped by the resin, it generates low dust and low outgas. Further, unlike the grease, since the rotational resistance is extremely small, high-precision rotational performance can be obtained without causing an increase in torque. In addition, since fluidity is maintained, dust generation due to peeling, missing, and abrasion seen in the solid lubricating film is suppressed. Therefore, the rolling bearing of the present invention is suitable for use in a clean room such as a vacuum or a precision machine manufacturing factory.

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

  Hereinafter, the present invention will be further described 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 an endurance test apparatus. As shown in the figure, two test bearings 2 are loaded and fitted from both ends of the rotary shaft in two step portions of the rotary shaft 1 arranged horizontally. . A substantially sleeve-shaped bearing housing 3 is fitted to each of the two test bearings 2, and the test bearing housing 3 has a stepped portion on the outer diameter, and the stepped portion is abutted against the bearing housing 3. Are respectively fitted to the gate-shaped housings 5. The two gate-shaped housings 5 are mechanically joined to the intermediate plate 16 of the vacuum chamber 7 and support the test bearing 2 so that the rotary shaft 1 is kept horizontal.

  The test bearing 2 can be applied with a preload by 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 so that the temperature of the test bearing 2 can be raised as necessary.

  The test bearing 2 and the rotary shaft 1 supported by the portal housing 5 are all disposed inside the vacuum chamber 7. A coupling 9 is disposed at the end of the rotating shaft 1, and the rotation introducing shaft 10 that is coaxially connected to the coupling 9 can be rotated 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 make the inside of the vacuum chamber 7 a vacuum environment.

  For the vacuum-tightness of the rotation introducing 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 the vacuum pump is activated and the inside of the vacuum chamber 7 is made into a vacuum environment, when the rotation introducing shaft 10 is rotated by an external drive (not shown), the test bearing 2 also rotates. It is possible to perform a rotation test.

  At this time, when 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 and controlled by a sensor (thermocouple 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 material of the rotary shaft 1, the bearing housing 3, and the gate-type housing 5 is not particularly limited, but general mild steel, austenitic stainless steel such as SUS304, martensitic stainless steel such as SUS420, etc., ferrite such as SUS430 For example, precipitation hardening stainless steel such as SUS630 is used.

  The material of the spring 6 may be a general piano wire, oil tempered wire, etc., but when performing the test at an elevated temperature, when performing the test at 350 ° C. or higher, such as stainless steel such as SUS304 or SUS631, An alloy material having excellent heat resistance such as Inconel 600 or Inconel X-750 may be used.

  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, stainless steel such as SUS316L, SUS304, and SUS303 are used alone or in combination. Used for. When the test bearing 2 is heated and the test is performed, it is considered that the rotary shaft 1 is thermally expanded. Therefore, a coupling 9 having a sufficient allowable axial displacement that can absorb the thermal expansion length is selected. The Although not shown, a ball coupling or the like of a type in which a shaft and a cup covering the shaft and both of them are mechanically coupled with each other has a large allowable axial displacement, and therefore is suitable when the test bearing 2 is heated.

  Two support bearings 11 are arranged at equal positions from the center point of the two test bearings 2 on the rotary shaft 1, and the support bearings 11 are fitted into 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 center 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, the two test bearings 2 are subjected to a radial load, but each test bearing 2 is rotated so that the load is evenly loaded. 1 and parts attached thereto 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 rotary shaft 1 supported by the test bearing 2 and parts attached thereto.

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

  The gate-type housing 5 is fastened to a vacuum chamber intermediate plate 16 that is horizontally disposed at the center position in the depth direction of the vacuum chamber 7. A through hole 16A is provided, and the wire 13 is suspended through the center of the through hole 16A.

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

  Next, functions and effects of this apparatus will be described. Two test bearings 2 are inserted into the rotary shaft 1, the apparatus is assembled in a predetermined procedure, and the rotary shaft 1 is placed horizontally by the two portal housings 5. The rotary shaft 1 is rotationally constrainedly connected to the rotation introducing shaft 10 by a coupling 9. The rotation introducing shaft 10 is vacuum-sealed so as to be rotatable externally.

  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-tight manner.

  When the vacuum pump is operated, the inside of the vacuum chamber 7 becomes a vacuum environment. At this time, if the rotation introducing shaft 10 is rotated by an external drive mechanism (not shown), the rotating 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 in the bearing housing 3 is heated. At this time, a temperature sensor such as a thermocouple (not shown) is arranged in contact with the outer diameter of the test bearing 2 and the heater 4 is controlled, thereby enabling a test at a predetermined bearing temperature.

  A torque detector (not shown) is connected to the rotation introducing shaft 10 in a normal pressure environment, and the dynamic friction torque of the rotation introducing shaft 10 is constantly monitored during the test. If the operation of the test bearing 2 continues and eventually the test bearing 2 is damaged, some change occurs in the dynamic friction torque value of the test bearing 2, thereby causing a change in the dynamic friction torque value of the rotation introducing shaft 10. The occurrence of damage to the test bearing 2 can be detected. When the drive source of the rotation introducing shaft 10 is a servo motor or the like, the change in the dynamic friction torque value by the torque detector can be detected by monitoring the change in the servo voltage output value of the motor without installing the torque detector. It can be replaced with monitoring.

  If there is a change in the dynamic friction torque value or a change in the servo voltage output value, the test bearing 2 may have been damaged. Therefore, the test device is stopped and the test is terminated. The distance (total number of revolutions) is used as an index of durability performance.

The device specifications are as follows.
・ Test bearing:
Inner diameter: 8-40mm
Number: 2
Bearing orientation: Horizontal shaft Rotating wheel: Inner ring rotation
・ Rotational speed: 3000 min ^-1 maximum
・ Test environment: Vacuum
・ Bearing temperature: Max 400 ℃
・ Measurement item: Dynamic friction torque value

(Dust generation test equipment)
FIG. 3 shows the dust generation test apparatus. As shown in the figure, the center shaft 23 is coaxially fitted and fastened to the end 22A of the rotating shaft 22 supported horizontally by the two support bearings 21. ing. A test bearing 24 is coaxially fitted to the outer diameter of the center shaft 23, and an inner ring of the test bearing 24 is attached to the center shaft 23 mechanically by an inner ring retainer 25. The outer ring of the test bearing 24 is fitted coaxially to the test bearing housing 26, and the test bearing housing 26 is arranged coaxially with the rotating shaft 22. The outer ring end surface of the test bearing 24 is in contact with the end surface of the outer ring retainer 27 on the entire circumference, and is loaded by the compression spring 28 from the end surface of the outer ring retainer 27 to the right side of the drawing. Is held in.

  A coupling 29 is coaxially fitted to the end 22 </ b> A of the rotary shaft 22 and is mechanically coupled, and a motor shaft 30 </ b> A of a motor 30 (not shown) is coaxially arranged on the opposite side of the coupling 29. Are fitted together and are integrally coupled with each other.

  Therefore, if the motor 30 is driven to rotate, the rotating shaft 22 can rotate and the inner ring of the test bearing 24 can be rotated. 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. All the components that are mechanically connected to the outer diameter of the magnetic seal 31 are hermetically sealed by an O-ring to form an airtight chamber. Therefore, the end 22A of the rotary shaft 22 extends from the outside of the airtight chamber 32 to the inside. Inserted and kept airtight at the same time.

  Even if the rotating shaft 22 is rotated, the hermetic chamber 32 is maintained in an airtight state by the function of the magnetic seal 31. Therefore, the test bearing 24 is mechanically coupled to the end 22 </ b> A of the rotating shaft 22, thereby The test bearing 24 can be rotated inside. Since the inside of the airtight chamber 32 is kept in an airtight state, even if dust is generated from the support bearing 21, the dust does not enter the airtight chamber 32.

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

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

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

The test specifications are as follows.
・ Test bearing:
Inner diameter: 8-60mm
Number: 1
Bearing orientation: Horizontal shaft Rotating wheel: Inner ring rotation
・ Rotational speed: 3000 min ^-1 maximum
・ Test environment: normal pressure
・ Bearing temperature: normal temperature
・ Measurement items: Dust generation size and number

(Dynamic friction torque test equipment)
FIG. 4 shows the entire apparatus configuration, in which FIG. 1A is a side view and FIG. As shown in the figure, 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 other end of the rotating shaft 61 is fitted with the inner diameter of the test bearing 65 coaxially 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 right angle with the test bearing 65.

  An air pad 67 is coaxially disposed on the end surface of the outer cylinder 66 so as to face the pad surface. If air is conducted to the air pad 67, air is ejected from the pad surface of the air pad 67 and presses 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 connection shaft 68 is spherically connected to the center of the end surface opposite to the pad surface of the air pad 67, the posture of the air pad 67 can be freely maintained around the spherical seat. The connecting shaft 68 is connected to and supported by a load cell 69A. When the compression spring 70 in the vicinity of the load meter 69 </ b> A is compressed, the load meter 69 </ b> A moves forward with 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. The thread 72 extends in the direction perpendicular to the plane of the drawing, and is then coaxially connected to the shaft of another load meter 69B. 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. Thereafter, when the motor 64 is energized and rotated at a predetermined rotational 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. However, since the outer cylinder 66 and the load meter 69B are connected by the thread 72, the load meter 69B is prevented from rotating. The inner ring of the test bearing 65 continues to rotate, and the outer ring is stationary. The output value of the load meter 69B at this time is the accompanying force of the test bearing 65.

  If the radial dimension of the connection position of the pin 71 and the thread 72 is taken into account 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 a 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, the outer cylinder 66 is not loaded with frictional force from the air pad 67.

  In the case of rolling bearings, in the case of one-way rotation, a torque spike may be generated immediately after the start of rotation and a large dynamic friction torque value may be shown, but the dynamic friction torque value starts to settle in about one minute after the start of rotation, and then the rolling familiarity proceeds. Then, the dynamic friction torque value gradually decreases, and the value tends to settle about 15 minutes after the rotation is started. Therefore, the dynamic friction torque characteristics of the test bearing 65 can be roughly known by measuring the dynamic friction torque values at 1 minute and 15 minutes after the start of rotation.

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

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

(Vacuum high temperature durability test)
Test bearings of Example 1, Comparative Example 1-1, and Comparative Example 1-2 below were prepared.
Example 1
A fluorine-based lubricating oil A having a vapor pressure of 1 × 10 ⁻⁵ Pa at 38 ° C. and an average molecular weight of 6250 and PTFE powder having an average molecular weight of 3000 and an average particle diameter of about 4 μm in terms of mass ratio Lubricating lubricant: PTFE powder = 1: Mix at about 0.44 to prepare fluorinated lubricant A. Next, the fluorine-based lubricant A and the fluorine-based diluent solvent are diluted with a weight ratio of fluorine-based lubricant A: diluting solvent = 1: 14 to obtain a lubricant diluted solution A. Then, a SUS440C deep groove ball bearing (inner diameter: 8 mm) is immersed in the lubricant diluted solution A, and after lifting, the surfaces of the inner and outer rings are wiped, and the entire bearing is heated at 140 ° C. for about 30 minutes to form a lubricating film. A test bearing was prepared. The test bearing was equipped with a press cage.

(Comparative Example 1-1)
Lubricant diluted solution in which a fluorinated lubricating oil having an average molecular weight of 8400 as a main component and a fluorinated lubricating oil as a main component and a fluorinated diluted solvent are fluorinated lubricating oil B: diluted 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 (vapor pressure: 1 × 10 ⁻⁵ Pa) is used as the lubricating oil C, and the lubricating oil mainly composed of this and the diluent solvent are used in a mass ratio. C: A test bearing was produced in the same manner as in Example 1 except that the lubricant diluted solution C having a dilution solvent of 1:19 was used.

  In each test bearing, the space between the inner ring and the outer ring was exposed (no shield).

And using the durability test apparatus shown in FIG. 2, the vacuum high temperature durability was compared on the following test conditions.
・ Rotation speed: 3000 min ^-1
Test environment: Vacuum (about 1 × 10 ⁻¹ Pa)
・ Bearing temperature: 200 ℃
・ Load condition: Preload (Load condition is radial load P / C <5 (*)
(* P: Dynamic equivalent load, C: Basic dynamic constant load)
-Test termination condition: The dynamic friction torque value being monitored suddenly increases, abnormal noise or a large amount of wear
When powder is generated or a combination of these occurs, the test is completed.

  The test results are shown in FIG. 5, and Example 1 shows durability about 1.2 times that of Comparative Example 1-1 and about 1.4 times that of Comparative Example 1-2. Thus, it turns out that the rolling bearing of this invention is excellent in the 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 was formed by oil plating in the same manner as in Example 1, Comparative Example 1-1, and Comparative Example 1-2 to prepare a test bearing. In addition, the case where the test bearing similar to Example 1 is used is Example 2, and the case where the test bearing similar to Comparative Example 1-1 is used is the same test bearing as Comparative Example 2-1 and Comparative Example 1-2. The case where is used is referred to as Comparative Example 2-2.

And the dynamic friction torque value of each test bearing was compared using the dynamic friction torque test apparatus shown in FIG. The test conditions are as follows.
・ Rotational speed: 1000 min ^-1
・ Test environment: normal pressure ・ Bearing temperature: normal temperature ・ Loading conditions: axial load and radial load ・ Measuring time: 1 minute and 15 minutes after starting rotation ・ Measurement item: bearing swing force

  In Comparative Examples 2-1 and 2-2, the blending ratio of the lubricating oil and the dilution solvent is 1:19, and the dilution ratio is larger than the blending ratio (1:12 to 1:16) defined in the present invention. . Therefore, when the same oil plating process 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 adhesion amount of the lubricating oil is a factor that increases the dynamic friction torque value of the bearing, the dynamic friction torque values are usually larger in Comparative Examples 2-1 and 2-2 than in Example 2. As shown in FIG. 6, the test result shows that the dynamic friction torque value of Example 2 is smaller.

  It is considered that the larger the adhesion amount of lubricating oil is, the larger the dynamic friction torque value is. However, the blending ratio of the fluorolubricating oil amount and the fluororesin is within the scope of the present invention. By making it within the range of the present invention, it is possible to prevent the dynamic friction torque value from increasing and keep it at a small value without extremely reducing the amount of the fluorinated lubricant.

  As described above, if the oil plating treatment is performed within the scope of the present invention, the blending ratio of the fluorinated lubricant and the fluororesin, and the blending ratio of the fluorinated lubricant and the diluent solvent, the amount of the fluorinated lubricant is reduced. A rolling bearing having a small dynamic friction torque value can be obtained without extremely reducing it.

(Dust generation test)
As a test bearing, Example 2, Comparative Example 2-1, and Comparative Example 2-2 were used. In addition, the case where the test bearing of Example 2 is used is compared with Example 3, the case where the test bearing of Comparative Example 1-1 is used is compared with the case where the test bearing of Comparative Example 3-2 and Comparative Example 1-2 is used. This is Example 3-2.

Then, the number of particles of 0.1 μm or less generated from each test bearing was counted using the dust generation test apparatus shown in FIG. 3, and the number 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 , 4 times the number of measured particles, converted to 1 ft 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, Example 3 is 0 to several per 1 ft ³ at a rotational speed of 300 min ⁻¹ , whereas Comparative Example 3-1 is about 2000 and Comparative Example 3-2 is about 4000. is there. In terms of cleanliness class, Example 3 is Cleanness Class 1, Comparative Example 3-1 is Class 100, and Comparative Example 3-2 is Class 1000.

Moreover, as shown in FIG. 8, Example 3 is around 0 to 10 at 1000 min- ¹ , whereas Comparative Example 3-1 is around 100,000 and Comparative Example 3-2 is around 600,000. is there. In terms of cleanliness class, Example 3 is cleanliness class 1, comparative example 3-1 is cleanliness class 10000, and comparative example 3-2 is cleanliness class 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 dilution solvent was 1:19, and the dilution ratio was large compared to the range of the present invention (1:12 to 1:16). When the treatment is performed, it is considered that the total weight of the lubricating oil adhering to the bearing is smaller in Comparative Examples 3-1 and 3-2. The smaller the amount of adhesion of lubricating oil, the fewer particles generated from the bearings. Therefore, the number of particles is usually smaller in Comparative Examples 3-1 and 3-2 than in Example 3. As shown in FIG. 7 and FIG. 8, the result of Example 3 is smaller.

  As described above, if the oil plating treatment is performed within the scope of the present invention, the blending ratio of the fluorinated lubricant and the fluororesin, and the blending ratio of the fluorinated lubricant and the diluent solvent, the amount of the fluorinated lubricant is reduced. A rolling bearing with a small number of generated particles can be obtained without being extremely reduced.

(Verification of blending ratio of fluorinated lubricant in diluted lubricant solution-1)
Using a deep groove ball bearing having an inner diameter of 20 mm, a lubricating coating was formed by oil plating in the same manner as in Example 1 to produce a test bearing. A case where a test bearing similar to that in Example 1 is used is referred to as Example 4.

  In addition, the content (mixing ratio) of the fluorine-based lubricating oil in the lubricant diluted solution was 1.7 times that in Example 4, and a lubricating coating was formed by oil plating in the same manner as in Example 4 to produce a test bearing. And it was set as Comparative Example 4-1. Furthermore, a test bearing in which the content (mixing ratio) of the fluorine-based lubricating oil in the lubricant diluted solution was 3.3 times that of Example 4 was referred to as Comparative Example 4-2.

And the dynamic friction torque value of each test bearing was compared using the dynamic friction torque test apparatus shown in FIG. The test conditions are as follows.
・ Rotational speed: 1000 min ^-1
・ Test environment: normal pressure ・ Bearing temperature: normal temperature ・ Loading conditions: axial load and radial load ・ Measuring time: 1 minute and 15 minutes after starting rotation ・ Measurement item: bearing swing force

  The content (blending ratio) of the fluorine-based lubricating oil in the lubricant diluted solution is 1.7 times in Comparative Example 4-1, and 3.3 times in Comparative Example 4-2, as compared to Example 4. Since all three test bearings formed a lubricating film by the same oil plating treatment, the amount of fluorine-based lubricating oil adhering to the bearings was approximately 1 in Comparative Example 4-1, assuming that Example 4 was 1.0. 7, Comparative Example 4-2 is approximately 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 adhesion amount of the fluorinated lubricant. That is, it can be seen that as the adhesion amount of the fluorinated lubricant is increased, the dynamic friction torque value is increased accordingly. On the other hand, as shown in FIG. 6, Example 2 (same as Example 4) has a smaller dynamic friction torque value than Comparative Examples 2-1 and 2-2. That is, it can be said that the blending ratio of the fluorinated lubricant defined in the present invention is an appropriate amount in terms of the dynamic friction torque value of the rolling bearing. In other words, the blending ratio of the fluorinated lubricating oil and the fluororesin is within the scope of the present invention, and the blending ratio of the fluorinated lubricating oil and the dilution solvent is also within the scope of the present invention, so that the amount of the fluorinated lubricating oil is extremely reduced. Without decreasing, it is possible to prevent the dynamic friction torque value from increasing and keep it at a small value.

  As described above, if the oil plating treatment is performed within the scope of the present invention, the blending ratio of the fluorinated lubricant and the fluororesin, and the blending ratio of the fluorinated lubricant and the diluent solvent, the amount of the fluorinated lubricant is reduced. A rolling bearing having a small dynamic friction torque value can be obtained without extremely reducing it.

(Verification of blending ratio of fluorinated lubricant in diluted lubricant solution-2)
As a test bearing, Example 4, Comparative Example 4-1, and Comparative Example 4-2 were used. In addition, the case where the test bearing of Example 4 is used is compared with Example 5, 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 and Comparative Example 4-2 is used. This is Example 5-2.

Then, the number of particles of 0.1 μm or less generated from each test bearing was counted using the dust generation test apparatus shown in FIG. 3, and the number per 1 ft ³ was compared. The test conditions are as follows.
・ Rotational speed: 1000 min ^-1
・ Test environment: normal pressure ・ Bearing temperature: normal temperature ・ Load condition: preload only ・ Measuring device: particle counter ・ Measurement flow rate: 0.25 ft ³ /2.5 min, 4 times the number of measured particles and converted to 1 ft ³・Number of measurements: 24 times

The result is shown in FIG. 10 (the result of Example 5 is diverted from the result of Example 3 at 1000 min ⁻¹ ). When the number of particles is 0, it is described as “1” for convenience. While Example 5 is around 0 to 10 per 1 ft ³ , Comparative Example 5-1 is around 400 and Comparative Example 5-2 is around 4000. In terms of cleanliness class, Example 5 is cleanliness class 1, comparative example 5-1 is cleanliness class 100, and comparative example 5-2 is cleanliness class 1000.

  The content (mixing ratio) of the fluorine-based lubricating oil in the lubricant diluted 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 all three test bearings formed a lubricating film by the same oil plating treatment, the amount of fluorine-based lubricating oil adhering to the bearings was approximately 1 in Comparative Example 5-1, assuming that Example 5 was 1.0. .7, Comparative Example 5-2 is approximately 3.3.

  As shown in FIG. 10, the number of particles increases in the order of the adhesion amount of the fluorine-based lubricating oil. That is, it can be seen that the number of particles increases as the adhesion amount of the fluorinated lubricant increases.

  On the other hand, as shown in FIG. 5, Example 1 (same as Example 5) has a higher durability performance 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 defined in the present invention is an appropriate amount in terms of the high temperature durability performance of the rolling bearing. In other words, the blending ratio of the fluorine-based lubricating oil and the fluororesin is within the scope of the present invention, and the blending ratio of the fluorine-based lubricating oil and the diluting solvent is also within the scope of the present invention. Therefore, it is possible to prevent the vacuum high-temperature performance from being reduced and to maintain a large vacuum high-temperature durability performance.

  As described above, if the oil plating treatment is performed within the scope of the present invention, the blending ratio of the fluorinated lubricant and the fluororesin, and the blending ratio of the fluorinated lubricant and the diluent solvent, the amount of the fluorinated lubricant is reduced. A rolling bearing having a small dynamic friction torque value can be obtained without extremely reducing it.

1 Rotating shaft 2 Test bearing 3 Bearing housing 4 Heater 5 Portal housing 6 Spring
7 Vacuum chamber 7A Bottom 8 Exhaust port 9 Coupling 10 Rotation introducing 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 chamber
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)

At least one of the raceway surface of the inner and outer rings and the rolling surface of the rolling element,
A fluorine-based lubricating oil 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 in terms of mass ratio. : A rolling bearing having a lubricating film made of a fluorine-based lubricant 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 fluorine-based lubricating oil 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 in terms of mass ratio. : Fluorine resin = 1: 0.40 to 1: 0.48 in a ratio of fluorine lubricant and diluent solvent, fluorine lubricant: diluent solvent = 1: 12 to 1:16 by mass ratio A method for manufacturing a rolling bearing, comprising: subjecting at least one of raceway surfaces of inner and outer rings and rolling surfaces of rolling elements to oil plating using the diluted lubricant solution mixed in (1).   4. The method of manufacturing a rolling bearing according to claim 3, wherein after the oil plating treatment, heating is performed at 100 ° C. to 250 ° C. for 15 minutes to 60 minutes. 5.

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