WO2014156206A1 - Rolling bearing for electric corrosion prevention - Google Patents

Rolling bearing for electric corrosion prevention Download PDF

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Publication number
WO2014156206A1
WO2014156206A1 PCT/JP2014/050048 JP2014050048W WO2014156206A1 WO 2014156206 A1 WO2014156206 A1 WO 2014156206A1 JP 2014050048 W JP2014050048 W JP 2014050048W WO 2014156206 A1 WO2014156206 A1 WO 2014156206A1
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WO
WIPO (PCT)
Prior art keywords
rolling bearing
ceramic
outer ring
sprayed coating
inner ring
Prior art date
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PCT/JP2014/050048
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French (fr)
Japanese (ja)
Inventor
志向 虻川
水津　竜夫
Original Assignee
トーカロ株式会社
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Publication date
Application filed by トーカロ株式会社 filed Critical トーカロ株式会社
Priority to CN201480017826.7A priority Critical patent/CN105051390A/en
Publication of WO2014156206A1 publication Critical patent/WO2014156206A1/en

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C33/00—Parts of bearings; Special methods for making bearings or parts thereof
    • F16C33/30—Parts of ball or roller bearings
    • F16C33/58—Raceways; Race rings
    • F16C33/64—Special methods of manufacture
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C4/00—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge
    • C23C4/04—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge characterised by the coating material
    • C23C4/10—Oxides, borides, carbides, nitrides or silicides; Mixtures thereof
    • C23C4/11—Oxides
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C4/00—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge
    • C23C4/12—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge characterised by the method of spraying
    • C23C4/134—Plasma spraying
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C19/00—Bearings with rolling contact, for exclusively rotary movement
    • F16C19/52—Bearings with rolling contact, for exclusively rotary movement with devices affected by abnormal or undesired conditions
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C33/00—Parts of bearings; Special methods for making bearings or parts thereof
    • F16C33/30—Parts of ball or roller bearings
    • F16C33/58—Raceways; Race rings
    • F16C33/583—Details of specific parts of races
    • F16C33/586—Details of specific parts of races outside the space between the races, e.g. end faces or bore of inner ring
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C33/00—Parts of bearings; Special methods for making bearings or parts thereof
    • F16C33/30—Parts of ball or roller bearings
    • F16C33/58—Raceways; Race rings
    • F16C33/62—Selection of substances
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C35/00—Rigid support of bearing units; Housings, e.g. caps, covers
    • F16C35/04—Rigid support of bearing units; Housings, e.g. caps, covers in the case of ball or roller bearings
    • F16C35/06—Mounting or dismounting of ball or roller bearings; Fixing them onto shaft or in housing
    • F16C35/063—Fixing them on the shaft
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C35/00—Rigid support of bearing units; Housings, e.g. caps, covers
    • F16C35/04—Rigid support of bearing units; Housings, e.g. caps, covers in the case of ball or roller bearings
    • F16C35/06—Mounting or dismounting of ball or roller bearings; Fixing them onto shaft or in housing
    • F16C35/067—Fixing them in a housing
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C19/00—Bearings with rolling contact, for exclusively rotary movement
    • F16C19/02—Bearings with rolling contact, for exclusively rotary movement with bearing balls essentially of the same size in one or more circular rows
    • F16C19/04—Bearings with rolling contact, for exclusively rotary movement with bearing balls essentially of the same size in one or more circular rows for radial load mainly
    • F16C19/06—Bearings with rolling contact, for exclusively rotary movement with bearing balls essentially of the same size in one or more circular rows for radial load mainly with a single row or balls
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C2206/00—Materials with ceramics, cermets, hard carbon or similar non-metallic hard materials as main constituents
    • F16C2206/40—Ceramics, e.g. carbides, nitrides, oxides, borides of a metal
    • F16C2206/42—Ceramics, e.g. carbides, nitrides, oxides, borides of a metal based on ceramic oxides
    • F16C2206/44—Ceramics, e.g. carbides, nitrides, oxides, borides of a metal based on ceramic oxides based on aluminium oxide (Al2O3)
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C2223/00—Surface treatments; Hardening; Coating
    • F16C2223/30—Coating surfaces
    • F16C2223/42—Coating surfaces by spraying the coating material, e.g. plasma spraying
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C2380/00—Electrical apparatus
    • F16C2380/26—Dynamo-electric machines or combinations therewith, e.g. electro-motors and generators

Definitions

  • the present invention relates to a rolling bearing, and more particularly to a rolling bearing for preventing electric corrosion in which electric corrosion caused by current generated in an electric motor of a railway vehicle or the like is prevented by coating a ceramic spray coating.
  • a rolling bearing provided with a metal outer ring and a metal inner ring disposed concentrically with the outer ring via a rolling element on the inner side in the radial direction of the outer ring as a bearing for a rotating shaft or the like of an electric motor of a railway vehicle Is commonly used.
  • a current generated by the electric motor or the like flows through an outer ring, a rolling element, and an inner ring.
  • the current flowing through the rolling bearing sparks at the contact surface between the rolling elements and the inner and outer rings, and electric corrosion occurs on the outer ring, the rolling elements, and the inner ring that form a current path. Electrical corrosion not only degrades the performance of rolling bearings, but also causes a reduction in life.
  • the outer surface of the outer ring of the rolling bearing that contacts the housing may be covered with an insulating material.
  • a ceramic material is suitable, and in order to coat with the ceramic material, a ceramic film is formed on the outer surface of the outer ring of the rolling bearing by a thermal spraying method.
  • Patent Document 1 and Patent Document 2 describe an electric corrosion prevention rolling bearing in which the outer surface of the outer ring of the rolling bearing is roughened and a ceramic sprayed coating of 0.15 to 0.45 mm is formed on the surface. Yes.
  • a rolling bearing in which a ceramic sprayed coating made of gray alumina containing aluminum oxide and titanium oxide is formed on the outer surface of the outer ring with a predetermined thickness (Patent Document 3).
  • a rolling bearing is known in which a ceramic sprayed coating having alumina as a main component and titanium oxide content of 0.01 to 0.2% by weight is formed on the outer surface of an outer ring (Patent Document 4).
  • the particle size of the ceramic powder for forming the ceramic spray coating is 10 to 50 ⁇ m.
  • Patent Document 5 a ceramic sprayed coating having a porosity of 2 to 6% is formed on the outer surface of the outer ring and further filled with an organic sealant.
  • the surface of the outer ring attached to the housing is coated with a ceramic coating layer and two metal layers thereon.
  • Patent Document 7 describes a rolling bearing in which the outer surface of the outer ring of the rolling bearing is roughened to Ra of 1.0 to 3.0 ⁇ m and a ceramic film is formed on the roughened surface.
  • an object of the present invention is to provide a rolling bearing for preventing electric corrosion that can greatly improve durability.
  • a rolling bearing for preventing electric corrosion of the present invention includes a metal outer ring, a metal inner ring that is concentrically disposed via the outer ring and a plurality of rolling elements, and is relatively rotatable, and the outer ring or the A ceramic sprayed coating for preventing electric corrosion formed on the outer surface of the inner ring by a plasma spraying method, and the volume resistivity of the ceramic sprayed coating is 10 6 ⁇ cm to 10 13 ⁇ cm, It is a rolling bearing for corrosion prevention.
  • the volume resistivity of the ceramic sprayed coating is set to 10 6 ⁇ cm to 10 13 ⁇ cm, and the current is not completely cut off while maintaining the insulation performance, so that a very large voltage is applied.
  • local electric field concentration does not occur. Therefore, even if a momentary load with a very large voltage is repeated for a long period of time, the insulation performance is not impaired, and damage to the rolling bearing for preventing electrolytic corrosion is prevented. Thereby, durability can be improved significantly.
  • the film thickness of the ceramic sprayed coating is preferably 50 ⁇ m to 100 ⁇ m.
  • the effect of reducing the manufacturing cost is great, and the mechanical strength is reduced due to the shear stress generated between the outer ring and the inner ring of the rolling bearing and the residual stress inside the film in a usage environment with a large temperature difference. It is difficult to occur, and damage such as peeling or cracking of the film can be prevented.
  • the ceramic spray coating is composed of a material mainly composed of aluminum oxide and titanium oxide
  • the content of aluminum oxide is set to 60% by weight to 98% by weight
  • the content may be 2 wt% to 40 wt%.
  • the ceramic sprayed coating is subjected to a sealing treatment with an organic resin, and the surface roughness Ra after the finishing treatment applied after the sealing treatment is less than 1 ⁇ m, and the skewness Rsk is less than 0.
  • the surface roughness Ra of the surface layer is less than 1 ⁇ m and the skewness Rsk, which is a measure of surface irregularities, is less than 0, there are few protrusions on the surface. Therefore, the electric field concentration occurring on the surface when a current flows can be reduced, and the durability can be further improved.
  • the surface roughness before spraying of the outer surface of the outer ring or the inner ring coated with the ceramic spray coating is Ra: 0.5 ⁇ m to 2.0 ⁇ m, high adhesion to the ceramic spray coating can be obtained. it can.
  • the ceramic sprayed coating is preferably formed using a powder having an average particle diameter of 3 ⁇ m to 15 ⁇ m as a raw material.
  • a ceramic sprayed coating having a volume resistivity of 10 6 ⁇ cm to 10 13 ⁇ cm is formed so that the current is not completely cut off while maintaining the insulation performance. Can be improved.
  • FIG. 1 is a cross-sectional view of a rolling bearing for preventing electrolytic corrosion according to an embodiment of the present invention in which a ceramic sprayed coating is formed on an outer ring. It is sectional drawing of the rolling bearing for electrolytic corrosion prevention which concerns on other embodiment which formed the ceramic sprayed coating in the inner ring
  • FIG. 1 is a cross-sectional view of a rolling bearing 1 for preventing electric corrosion according to an embodiment of the present invention.
  • the rolling bearing 1 for preventing electric corrosion is a ball bearing using balls as rolling elements, and is a ring-shaped metal outer ring 2 and a ring-shaped metal that is arranged concentrically with the outer ring 2 and is relatively rotatable.
  • the inner ring 3 is mainly composed of a made inner ring 3, a ring-shaped cage 4 arranged between the outer ring 2 and the inner ring 3, and a plurality of rolling elements 5 held by the cage 4.
  • this invention is not limited to this embodiment, It applies to the rolling bearing for an electric corrosion prevention provided with another shape, a form, or another member. Examples of other electric corrosion prevention rolling bearings include a tapered roller bearing and a cylindrical roller bearing.
  • An outer ring side raceway surface 2a having a circular arc shape is formed on the inner periphery of the outer ring 2, and outer ring side small diameter portions 2b and the like are formed on both sides of the outer ring side raceway surface 2a.
  • An inner ring side raceway surface 3a having a circular arc shape is formed on the outer periphery of the inner ring 3, and inner ring side small diameter portions 3b and the like are formed on both sides of the inner ring side raceway surface 3a.
  • the cage 4 has a plurality of pocket portions 4a in the circumferential direction, and a metallic and spherical rolling element 5 is rotatably held in each pocket portion 4a.
  • the plurality of rolling elements 5 roll on the outer ring side raceway surface 2 a and the inner ring side raceway surface 3 a, and the rolling element 5 moves in the same direction as the rotation direction of the inner ring 3.
  • the cage 4 that holds the plurality of rolling elements 5 also moves in the same direction as the rolling elements 5.
  • the electric corrosion prevention rolling bearing 1 is mainly applied to a rolling bearing that supports a rotating shaft of an electric motor, a generator, or an electric device of a vehicle, and current generated by the electric motor or the like generates an outer ring 2, a rolling element 5, an inner ring 3. It is a rolling bearing that prevents electric corrosion from occurring in the rolling bearing 1 for preventing electric corrosion when flowing through the shaft.
  • the outer ring 2 is fixed in contact with a housing (not shown) for attaching the rolling bearing 1 for preventing electric corrosion.
  • An electrolytic corrosion preventing function is imparted to the entire outer surface 21 of the outer ring 2 that is a contact portion with the housing. Increasing the electric resistance of the outer surface 21 of the outer ring 2 makes it difficult for a local current such as a spark to flow through the rolling bearing 1 for preventing electric corrosion, thereby preventing electric corrosion.
  • a ceramic spray coating 10 is formed on the outer surface 21 of the outer ring 2.
  • the ceramic sprayed coating 10 is formed on the outer ring 2, but a similar ceramic sprayed coating may be formed on the outer surface 31 of the inner ring 3 as shown in FIG. In this case, the outer surface 31 of the inner ring 3 comes into contact with a rotating shaft (not shown).
  • Ceramic materials for forming a thermal spray coating generally, Al 2 O 3 , MgO, TiO 2 , Cr 2 O 3 , ZrO 2 , HfO 2 , SiO 2 , Y 2 O 3 , Al 2 O 3 .TiO 2 , Al 2 O 3 .SiO 2 , Al 2 O 3 .MgO, and the like are known.
  • a ceramic constituting the ceramic sprayed coating 10 of the present embodiment a material mainly composed of aluminum oxide, titanium oxide, or the like can be used.
  • gray alumina Al 2 O 3 , TiO 2
  • alumina yttria 3Al 2 O 3 ⁇ 5Y 2 O 3
  • alumina magnesia Mg ⁇ Al 2 O 4
  • alumina ⁇ silica 3Al 2 O 3 ⁇ 2SiO 2
  • gray alumina mainly composed of aluminum oxide and titanium oxide is suitable.
  • White alumina (Al 2 O 3 ), which has a high dielectric breakdown voltage and a high volume resistivity, is known as a material for a ceramic spray coating for preventing electrolytic corrosion.
  • the gray alumina (Al 2 O 3 , TiO 2 ) contains titanium oxide, which is a conductive material. Gray alumina has a lower volume resistivity than white alumina, and a dielectric breakdown voltage lower than that of white alumina. .
  • a major reason for selecting gray alumina is low insulation due to the low volume resistivity. Moreover, the film formability can also be improved.
  • the melting point of titanium oxide (TiO 2 ) is lower than that of white alumina.
  • the titanium oxide (TiO 2 ) is more easily adhered to the metal substrate than the case where the aluminum oxide (Al 2 O 3 ) is 100%, and a uniform film is formed. Cheap. Therefore, the yield is better when gray alumina is selected, and the manufacturing cost can be reduced.
  • gray alumina which is a material mainly composed of aluminum oxide and titanium oxide is most preferably used. It is done.
  • the content of aluminum oxide in the ceramic sprayed coating is set to 60 wt% to 98 wt%, and the content of titanium oxide is set to 2 wt% to 40 wt%. More preferably, the content of aluminum oxide is 70 to 90% by weight, and the content of titanium oxide is 10 to 30% by weight.
  • the volume resistivity of the ceramic sprayed coating 10 is adjusted to 10 6 ⁇ cm to 10 13 ⁇ cm.
  • a more preferable range of the volume resistivity of the ceramic sprayed coating 10 is 10 8 ⁇ cm to 10 10 ⁇ cm.
  • the reason why a relatively large amount of titanium oxide is contained in the ceramic sprayed coating is that the volume resistivity is adjusted to 10 6 ⁇ cm to 10 13 ⁇ cm to obtain a low insulating property.
  • the current is not completely cut off while maintaining the required insulation performance. By doing so, local electric field concentration does not occur even when a very large voltage is applied. Therefore, even if a momentary load with a very large voltage is repeated for a long period of time, the insulation performance is not impaired, and damage to the electric corrosion prevention rolling bearing 1 is prevented for a long period of time.
  • a strong shear stress may occur at the interface between the outer ring 2 or the inner ring 3 of the rolling bearing 1 for preventing electric corrosion and the ceramic sprayed coating 10.
  • the shear stress acts as a force to peel the ceramic sprayed coating 10 from the outer ring 2 or the inner ring 3 and causes peeling of the coating.
  • there is a residual stress due to thermal shrinkage that occurs during film formation inside the ceramic sprayed coating 10 and the mechanical strength may decrease due to the influence of the residual stress, leading to a decrease in impact resistance.
  • the film thickness of the ceramic sprayed coating 10 of the present embodiment is 50 ⁇ m to 100 ⁇ m, which is an extremely thin coating, so that the shear stress is small and the coating is hardly peeled off.
  • the residual stress at the time of film formation is small, it is difficult to cause a decrease in mechanical strength. Accordingly, damage such as peeling or cracking of the film can be prevented.
  • the significance of setting the upper limit of the film thickness of the ceramic sprayed coating 10 to 100 ⁇ m is as described above, and the lower limit of the film thickness is set to 50 ⁇ m because the insulating performance cannot be maintained if the film thickness is smaller than this.
  • what is necessary is just to adjust the film-forming time, for example, in order to control the film thickness of the ceramic sprayed coating 10.
  • the surface layer of the ceramic sprayed coating 10 is subjected to a sealing treatment to close the pores.
  • the thermal spray coating generally has pores in principle, and depending on the pore structure of the thermal spray coating, gas or liquid may permeate the coated substrate. If the sealing treatment is not performed, for example, water enters the pores and the insulating performance is lowered.
  • the sealing agent not only seals the pores of the sprayed layer, but also has a function of maintaining the adhesion of the coating after the sealing treatment.
  • the porosity of the ceramic sprayed coating 10 is set to 6% or less. When the porosity of the ceramic sprayed coating 10 is larger than 6%, the sealing agent may not be sufficiently filled, and the function of the sealing agent cannot be exhibited.
  • the porosity can be controlled by adjusting the particle size of the ceramic powder, adjusting the distance between the spray gun and the outer surfaces 21 and 31 of the outer ring 2 or inner ring 3 to be treated, and adjusting the pressure of the spraying atmosphere. it can.
  • the organic resin for sealing treatment may be any resin that has fluidity so as to enter the pores of the ceramic sprayed coating 10.
  • synthetic resins include, for example, bisphenol F type epoxy resin, bisphenol A type epoxy resin, epoxy resin such as polyglycidyl (meth) acrylate, acrylic resin, fluorine resin, urethane resin, phenol resin, xylene resin, polyester resin, unsaturated resin
  • Known synthetic resins such as polyester resins, polyamide resins, and melamine resins can be used. These can be used alone or in admixture of two or more.
  • the ceramic spray coating 10 is formed by spraying ceramic powder having an average particle size of 3 ⁇ m to 15 ⁇ m.
  • the porosity of the sprayed layer can be controlled to 6% or less, and variation in pore size can be suppressed.
  • a ceramic powder having a small particle diameter as in this embodiment, a ceramic sprayed coating 10 having small pores and uniform pore sizes can be obtained. If the pore size can be made uniform, the filling degree of the sealing agent can be improved, which is advantageous from the viewpoint of suppressing the variation in insulating performance.
  • the average particle size of the ceramic powder is desirably small, but if it is too small, the fluidity of the ceramic powder may decrease during the thermal spraying process for forming the thermal spray coating, and there is a possibility that it cannot be stably supplied. If the ceramic powder is unevenly conveyed, the coating strength tends to vary and the thickness tends to be non-uniform. From such a viewpoint, it is preferable to use a ceramic powder having an average particle diameter in the range of 3 ⁇ m to 15 ⁇ m, more preferably 3 ⁇ m to 12 ⁇ m. When the average particle size of the ceramic powder exceeds 15 ⁇ m, a portion where the film is formed without being completely melted is formed, and the portion becomes excessively porous so that it becomes difficult to fill the sealing agent, and the insulating performance is deteriorated.
  • the ceramic sprayed coating 10 is subjected to a sealing treatment with an organic resin and then subjected to a finishing treatment such as polishing, and the surface properties are controlled so that the surface roughness Ra is less than 1 ⁇ m and the skewness Rsk is less than 0. Yes.
  • the surface roughness Ra defined in JISB0660 and the skewness Rsk defined in JISB0601 are used as indices.
  • the skewness Rsk is a physical quantity obtained by dividing the cube average of the height deviation in the reference length by the cube of the root mean square.
  • the skewness Rsk is a mathematical index that expresses the difference in surface irregularities, and serves as a standard indicating the symmetry of the irregularities on the target surface.
  • the value of the skewness Rsk is greatly influenced by the presence of a small number of protrusions and valleys remaining on the surface after polishing.
  • the skewness Rsk has a positive value when there are sharp protrusions on the surface and the convex area of the surface roughness is large, and approaches zero when the protrusions and valleys are symmetric. When the concave area of the surface roughness is large, a negative value is shown. Therefore, the outer ring 2 or the inner ring 3 of the rolling bearing 1 for preventing electric corrosion having a surface roughness Ra of less than 1 ⁇ m and a skewness Rsk of less than 0 has a surface property with very few sharp protrusions.
  • the surface properties may be controlled by adjusting the particle size of the ceramic powder during spraying.
  • the ceramic spray coating 10 is obtained by supplying ceramic powder into a heat source, spraying the ceramic powder on the outer surfaces 21 and 31 of the outer ring 2 or the inner ring 3 while heating and melting it, and depositing molten particles.
  • the ceramic powder is supplied in units of tens of thousands of pieces continuously into the heat source. As a result, particles having different flatness are deposited randomly.
  • the surface roughness Ra and skewness Rsk can be controlled to show the above values by using ceramic powder having an average particle size in the range of 3 ⁇ m to 15 ⁇ m as in this embodiment. Furthermore, the surface roughness Ra and the skewness Rsk can easily exhibit the above values by performing a sealing treatment with an organic resin.
  • the ceramic sprayed coating 10 is formed by any one of the atmospheric plasma spraying method, the low pressure plasma spraying method, the high-speed flame spraying method, the gas flame spraying method, the arc spraying method, the water plasma spraying method, the electric arc spraying method, and the explosion spraying method.
  • the film forming conditions by each thermal spraying method may be appropriately set according to the base material, raw material powder, film thickness, manufacturing environment, and the like.
  • the plasma spraying method is a thermal spraying method using electric energy as a heat source, and forms a film using argon or hydrogen as a plasma generation source. Since the heat source temperature is high and the frame speed is high, a high melting point ceramic material can be densely formed, which is suitable for the method of manufacturing the ceramic sprayed coating 10.
  • An example of a process for obtaining the ceramic sprayed coating 10 is to clean the outer surfaces 21 and 31 of the outer ring 2 or the inner ring 3 which is a base material, roughening the outer surfaces 21 and 31 by blasting, under The coating treatment, the thermal spraying of the ceramic sprayed coating 10 as the top coat, the sealing treatment of the surface layer of the ceramic sprayed coating 10, and the surface polishing treatment are performed in this order.
  • the undercoat process may be omitted depending on the difference in the thermal spray material, and other processes such as a preheating process may be included.
  • the undercoat improves the adhesion between the outer surfaces 21 and 31 of the outer ring 2 or the inner ring 3 and the ceramic sprayed coating 10 and prevents peeling or cracking of the coating.
  • the undercoat is not necessarily provided, and when the ceramic powder is directly sprayed onto the outer ring 2 or the inner ring 3, the spraying conditions may be employed so that the ceramic powder can be completely melted.
  • the average particle diameter of the ceramic powder may be in the range of 3 ⁇ m to 15 ⁇ m as in this embodiment, and the plasma heat source, the flight speed of the plasma particles, etc. may be optimized.
  • the ceramic sprayed coating 10 is formed on the outer surface 21 of the outer ring 2 or the outer surface 31 of the inner ring 3 of the rolling bearing 1 for preventing electric corrosion, for example, a rotating shaft of an electric motor for a railway vehicle, power generation Even if a voltage is generated on the rotating shaft of the machine, the rolling bearing 1 that supports the rotating shaft can exhibit an electrolytic corrosion preventing effect. Even when a high voltage of, for example, about 3 kV is repeatedly applied to the outer surfaces 21 and 31 of the outer ring 2 or the inner ring 3 over a long period of time, it is possible to continue to maintain the electrolytic corrosion prevention effect.
  • the ceramic sprayed coating 10 is provided in a single layer structure on the outer ring 2 or the inner ring 3 of the rolling bearing 1 for preventing electric corrosion.
  • different ceramic sprayed coatings may be formed in multiple layers, or the ceramic sprayed coating.
  • Another metal layer may be provided on the upper layer.
  • the volume resistivity of the ceramic sprayed coating 10 is set to 10 6 ⁇ cm to 10 13 ⁇ cm, and the current is not completely cut off while maintaining the insulation performance. Therefore, even when a very large voltage is applied, local electric field concentration does not occur. Therefore, even if a momentary load with a very large voltage is repeated for a long period of time, the insulation performance is not impaired, and damage to the electric corrosion prevention rolling bearing 1 is prevented. Thereby, durability can be improved significantly.
  • a test piece having a composition, film thickness, sealing treatment, substrate surface roughness, post-film formation surface roughness, and volume resistivity is manufactured and insulated on the surface of the metal substrate. Destructibility was evaluated. The dielectric breakdown property was evaluated by conducting a dielectric breakdown test and visually confirming the presence or absence of dielectric breakdown.
  • the dielectric breakdown test method is as follows. An 80 ⁇ 80 mm aluminum foil is placed in the center on the surface on which the test piece is formed, and a voltage is applied between the aluminum foil and the back side of the test piece. Gradually increase the voltage from 0 kV and apply up to 3 kV to confirm the presence or absence of dielectric breakdown (spark). As a withstand voltage tester, TOS-5101 manufactured by Kikusui Electronics Co., Ltd. was used.
  • the film thickness was measured using a standard outer micrometer M100 manufactured by Mitutoyo Corporation, and the surface roughness was measured using 2800G manufactured by Tokyo Seimitsu Surfcom.
  • the volume resistivity measurement method is as follows. An 80 ⁇ 80 mm aluminum foil is placed in the center on the surface on which the test piece is formed, and a voltage is applied between the aluminum foil and the back side of the test piece. The resistance value R is calculated by dividing the voltage by the current flowing at that time.
  • the volume resistivity ⁇ is expressed as follows using the area S (8 ⁇ 8 cm) and the film thickness d (cm).
  • One side of a SS400 flat plate of 100 x 100 x 10 mm is first roughened by blasting, then ceramic spraying is performed, the surface layer on which the film is formed is subjected to sealing treatment, and finally polishing finish is performed to obtain a test piece.
  • polishing finish was performed after ceramic spraying.
  • the roughening treatment was performed by alumina grid blasting
  • the sealing treatment was performed by applying an epoxy sealant and then firing
  • the final polishing finish was performed using a flat polishing machine.
  • a film may be formed on a curved surface of a cylindrical structure, for example.
  • evaluation is performed using a flat test piece. This is because the volume resistivity and dielectric breakdown voltage of the film are hardly affected by the shape of the substrate, and a more rigorous evaluation result is obtained by comparing with a flat test piece that easily obtains uniform conditions.
  • thermal spraying conditions are as follows. Thermal spraying method: plasma spraying method, current value: 600 A, argon gas flow rate: 40 NLPM, hydrogen gas flow rate: 8.5 NLPM, spraying distance: 100 mm, ladder scan (gun feed rate: 600 mm / sec, 3 mm pitch).
  • Table 1 shows the composition (titania content), film thickness, presence / absence of sealing treatment, substrate surface roughness, post-film surface roughness, volume resistivity, and dielectric breakdown test results of each example and comparative example.
  • the substrate surface roughness is the roughness after roughening one side of a flat plate by blasting, and the surface roughness after film formation is to seal the formed surface layer, It is the surface roughness after polishing finish. In the case of no sealing treatment, it is the surface roughness after the film-formed surface is polished.

Abstract

A rolling bearing (1) for electric corrosion prevention, comprising a metal outer ring (2) and a metal inner ring (3) that is arranged via a plurality of rolling bodies (5). A ceramic thermal spray coating film (10) for preventing electric corrosion is formed, by plasma spraying, on the outer surfaces (21, 31) of the outer ring (2) or inner ring (3). The ceramic thermal spray coating film (10) has: a film thickness of 50-100 µm; a composition of 60-98 wt% aluminum oxide and 2-40 wt% titanium oxide; a volume resistance adjusted to 106-1013 Ωcm; and increased durability so as to maintain insulation properties but not completely isolate current.

Description

電蝕防止用転がり軸受Rolling bearing for electric corrosion prevention
　本発明は転がり軸受に関するものであり、特に鉄道車両の電動モータ等で生じる電流による電蝕をセラミックス溶射皮膜を被覆することで防止した電蝕防止用転がり軸受に関する。 The present invention relates to a rolling bearing, and more particularly to a rolling bearing for preventing electric corrosion in which electric corrosion caused by current generated in an electric motor of a railway vehicle or the like is prevented by coating a ceramic spray coating.
　鉄道車両の電動モータの回転軸等の軸受として、金属製の外輪と、この外輪の径方向内側で転動体を介して当該外輪と同心状に配置された金属製の内輪とを備えた転がり軸受が一般に用いられている。鉄道車両の電動モータ、発電機、電気機器の回転軸を支承する転がり軸受には、電動モータ等で生じた電流が外輪、転動体、内輪を伝って流れる。転がり軸受を流れる電流は、転動体と内外輪の接触面でスパークを起こし、電流の通路となる外輪、転動体、内輪に電蝕が生じる。電蝕は転がり軸受の性能を低下させるばかりでなく、寿命減少の要因となる。 A rolling bearing provided with a metal outer ring and a metal inner ring disposed concentrically with the outer ring via a rolling element on the inner side in the radial direction of the outer ring as a bearing for a rotating shaft or the like of an electric motor of a railway vehicle Is commonly used. In a rolling bearing that supports a rotating shaft of an electric motor, a generator, and an electric device of a railway vehicle, a current generated by the electric motor or the like flows through an outer ring, a rolling element, and an inner ring. The current flowing through the rolling bearing sparks at the contact surface between the rolling elements and the inner and outer rings, and electric corrosion occurs on the outer ring, the rolling elements, and the inner ring that form a current path. Electrical corrosion not only degrades the performance of rolling bearings, but also causes a reduction in life.
　転がり軸受の例えば外輪とこれを支持するハウジングとの間を絶縁し、転がり軸受に電流が流れないようにすることで電蝕による寿命の低下を防ぐことができる。それには、ハウジングに接触する転がり軸受の外輪の外表面を絶縁材で被覆すればよい。絶縁材としてはセラミックス材料が好適であり、セラミックス材料で被覆するために、転がり軸受の外輪の外表面に溶射法によってセラミックス皮膜を形成することが行われている。 It is possible to prevent a decrease in the service life due to electrolytic corrosion by insulating between the outer ring of the rolling bearing, for example, and the housing supporting the rolling bearing so that no current flows through the rolling bearing. For this purpose, the outer surface of the outer ring of the rolling bearing that contacts the housing may be covered with an insulating material. As the insulating material, a ceramic material is suitable, and in order to coat with the ceramic material, a ceramic film is formed on the outer surface of the outer ring of the rolling bearing by a thermal spraying method.
　特許文献１及び特許文献２には、転がり軸受の外輪の外表面を粗面化し、その表面に０．１５～０．４５ｍｍのセラミックス溶射皮膜を形成している電蝕防止転がり軸受が記載されている。外輪の外表面に、アルミニウム酸化物及びチタン酸化物が含まれたグレイアルミナからなるセラミックス溶射皮膜を所定の薄さで形成した転がり軸受も知られている（特許文献３）。外輪の外表面に、アルミナを主成分とし、酸化チタンの含有量を０．０１～０．２重量％としたセラミックス溶射皮膜を形成した転がり軸受が知られている（特許文献４）。この従来技術では、セラミックス溶射皮膜を形成するためのセラミックス粉末の粒径を１０～５０μｍとしている。 Patent Document 1 and Patent Document 2 describe an electric corrosion prevention rolling bearing in which the outer surface of the outer ring of the rolling bearing is roughened and a ceramic sprayed coating of 0.15 to 0.45 mm is formed on the surface. Yes. There is also known a rolling bearing in which a ceramic sprayed coating made of gray alumina containing aluminum oxide and titanium oxide is formed on the outer surface of the outer ring with a predetermined thickness (Patent Document 3). A rolling bearing is known in which a ceramic sprayed coating having alumina as a main component and titanium oxide content of 0.01 to 0.2% by weight is formed on the outer surface of an outer ring (Patent Document 4). In this prior art, the particle size of the ceramic powder for forming the ceramic spray coating is 10 to 50 μm.
　特許文献５の転がり軸受では、外輪の外表面に、気孔率：２～６％のセラミックス溶射皮膜を形成して、さらに有機系の封孔剤を充填している。特許文献６に記載された転がり軸受では、ハウジングに取り付けられる外輪の表面を、セラミックス製の被覆層とその上の２層の金属層で被覆している。特許文献７には、転がり軸受の外輪の外表面をＲａで１．０～３．０μｍに粗面化して、粗面化された表面にセラミックス皮膜を形成した転がり軸受が記載されている。 In the rolling bearing of Patent Document 5, a ceramic sprayed coating having a porosity of 2 to 6% is formed on the outer surface of the outer ring and further filled with an organic sealant. In the rolling bearing described in Patent Document 6, the surface of the outer ring attached to the housing is coated with a ceramic coating layer and two metal layers thereon. Patent Document 7 describes a rolling bearing in which the outer surface of the outer ring of the rolling bearing is roughened to Ra of 1.0 to 3.0 μm and a ceramic film is formed on the roughened surface.
特開２０１１－１１７６０７号公報JP 2011-117607 A 特開２００７－１７０６７３号公報JP 2007-170673 A 特開２００９－２９９９０４号公報JP 2009-299904 A 特開２００７－１４７０７２号公報JP 2007-147072 A 特開２００８－５０６６９号公報JP 2008-50669 A 特開２００２－１８１０５４号公報JP 2002-181054 A 特開２００８－３２１２７号公報JP 2008-32127 A
　鉄道車両の電動モータ等では、長期に渡って高い絶縁性能を維持しなければならないことや、多様な使用環境下において場合によっては瞬間的に非常に高電圧になることを想定して転がり軸受に絶縁性能を付与しておく必要がある。しかしながら上記特許文献１～７では、転がり軸受の製造コスト、絶縁抵抗、密着性等を改善できるとされているものの、例えば通常とは異なる高い電圧が負荷された場合、その瞬間の電圧には耐えることはできても、これが長期間に渡って何度も繰り返されると絶縁破壊を起こしかねない。そのため、長期に渡る耐久性が低いといった問題がある。 For rolling stock electric motors, etc., rolling bearings are assumed to maintain high insulation performance over a long period of time, and in some cases, extremely high voltage may be instantaneously applied in various usage environments. It is necessary to provide insulation performance. However, in Patent Documents 1 to 7, although it is said that the manufacturing cost, insulation resistance, adhesion, etc. of the rolling bearing can be improved, for example, when a high voltage different from usual is loaded, it withstands the instantaneous voltage. If possible, it can cause dielectric breakdown if it is repeated many times over a long period of time. Therefore, there is a problem that durability over a long period is low.
　そこで本発明は上記従来技術の問題点に鑑み、耐久性を大幅に向上させることができる電蝕防止用転がり軸受を提供することを目的とする。 Therefore, in view of the above-mentioned problems of the prior art, an object of the present invention is to provide a rolling bearing for preventing electric corrosion that can greatly improve durability.
　上記目的を達成するため次の技術的手段を講じた。即ち本発明の電蝕防止用転がり軸受は、金属製の外輪と、この外輪と複数の転動体を介して同心状に配置されて相対回転自在とされた金属製の内輪と、前記外輪又は前記内輪の外表面に、プラズマ溶射法によって形成された電蝕防止用のセラミックス溶射皮膜と、を備え、前記セラミックス溶射皮膜の体積抵抗率が１０６Ωｃｍ～１０１３Ωｃｍであることを特徴とする電蝕防止用転がり軸受である。 In order to achieve the above objective, the following technical measures were taken. That is, a rolling bearing for preventing electric corrosion of the present invention includes a metal outer ring, a metal inner ring that is concentrically disposed via the outer ring and a plurality of rolling elements, and is relatively rotatable, and the outer ring or the A ceramic sprayed coating for preventing electric corrosion formed on the outer surface of the inner ring by a plasma spraying method, and the volume resistivity of the ceramic sprayed coating is 10 6 Ωcm to 10 13 Ωcm, It is a rolling bearing for corrosion prevention.
　上記の本発明によれば、セラミックス溶射皮膜の体積抵抗率が１０６Ωｃｍ～１０１３Ωｃｍとされており、絶縁性能を維持しつつも電流を完全に遮断しないので、非常に大きな電圧が負荷されても局所的な電界集中が生じなくなる。従って、非常に大きな電圧の瞬間的な負荷が長期に渡って繰り返されても絶縁性能が損なわれず、電蝕防止用転がり軸受の損傷が防止される。これにより、耐久性を大幅に向上させることができる。 According to the present invention, the volume resistivity of the ceramic sprayed coating is set to 10 6 Ωcm to 10 13 Ωcm, and the current is not completely cut off while maintaining the insulation performance, so that a very large voltage is applied. However, local electric field concentration does not occur. Therefore, even if a momentary load with a very large voltage is repeated for a long period of time, the insulation performance is not impaired, and damage to the rolling bearing for preventing electrolytic corrosion is prevented. Thereby, durability can be improved significantly.
　前記セラミックス溶射皮膜の膜厚が５０μｍ～１００μｍであることが好ましい。この場合、製造コストの低減効果が大きく、また、温度差の大きい使用環境下において転がり軸受の外輪又は内輪との間で生じる剪断応力や、皮膜内部の残留応力の影響による機械的強度の低下が起こり難く、皮膜の剥離や割れ等の損傷を招かないようにすることができる。 The film thickness of the ceramic sprayed coating is preferably 50 μm to 100 μm. In this case, the effect of reducing the manufacturing cost is great, and the mechanical strength is reduced due to the shear stress generated between the outer ring and the inner ring of the rolling bearing and the residual stress inside the film in a usage environment with a large temperature difference. It is difficult to occur, and damage such as peeling or cracking of the film can be prevented.
　耐久性を向上させるには、前記セラミックス溶射皮膜をアルミニウム酸化物及びチタン酸化物を主成分とする材料で構成し、アルミニウム酸化物の含有率を６０重量％～９８重量％とし、チタン酸化物の含有率を２重量％～４０重量％とすればよい。チタン酸化物の含有率の上限を４０重量％とすることで、電流を僅かに流すようにして高い耐久性を確保し、それと同時に溶射の際の成膜効率が高くなり製造コストを低減できる。 In order to improve the durability, the ceramic spray coating is composed of a material mainly composed of aluminum oxide and titanium oxide, the content of aluminum oxide is set to 60% by weight to 98% by weight, The content may be 2 wt% to 40 wt%. By setting the upper limit of the content of titanium oxide to 40% by weight, high durability can be ensured by passing a small amount of current, and at the same time, the film formation efficiency during thermal spraying can be increased and the manufacturing cost can be reduced.
　前記セラミックス溶射皮膜に有機系樹脂による封孔処理が施されていることが好ましく、更に封孔処理後に施される仕上げ処理後の表面粗さＲａが１μｍ未満であり、かつスキューネスＲｓｋが０未満であることが好ましい。表層の表面粗さＲａを１μｍ未満とし、表面の凹凸の目安となるスキューネスＲｓｋを０未満としているため、表面に突起が少ない。そのため、電流が流れたときに表面上で生じる電界集中の点在を少なくでき、耐久性をさらに向上させることができる。 It is preferable that the ceramic sprayed coating is subjected to a sealing treatment with an organic resin, and the surface roughness Ra after the finishing treatment applied after the sealing treatment is less than 1 μm, and the skewness Rsk is less than 0. Preferably there is. Since the surface roughness Ra of the surface layer is less than 1 μm and the skewness Rsk, which is a measure of surface irregularities, is less than 0, there are few protrusions on the surface. Therefore, the electric field concentration occurring on the surface when a current flows can be reduced, and the durability can be further improved.
　前記セラミックス溶射皮膜で被覆されている前記外輪又は前記内輪の外表面の溶射前の表面粗さをＲａ：０．５μｍ～２．０μｍとすれば、セラミックス溶射皮膜との高い密着性を得ることができる。 If the surface roughness before spraying of the outer surface of the outer ring or the inner ring coated with the ceramic spray coating is Ra: 0.5 μm to 2.0 μm, high adhesion to the ceramic spray coating can be obtained. it can.
　前記セラミックス溶射皮膜は、平均粒径：３μｍ～１５μｍの粉末を原料として形成されていることが好ましい。 The ceramic sprayed coating is preferably formed using a powder having an average particle diameter of 3 μm to 15 μm as a raw material.
　上記の通り本発明によれば、体積抵抗率が１０６Ωｃｍ～１０１３Ωｃｍのセラミックス溶射皮膜を形成して、絶縁性能を維持しつつも電流を完全に遮断しないようにしたので耐久性を大幅に向上させることができる。 As described above, according to the present invention, a ceramic sprayed coating having a volume resistivity of 10 6 Ωcm to 10 13 Ωcm is formed so that the current is not completely cut off while maintaining the insulation performance. Can be improved.
外輪にセラミックス溶射皮膜を形成した本発明の一実施形態に係る電蝕防止用転がり軸受の断面図である。1 is a cross-sectional view of a rolling bearing for preventing electrolytic corrosion according to an embodiment of the present invention in which a ceramic sprayed coating is formed on an outer ring. 内輪にセラミックス溶射皮膜を形成した他の実施形態に係る電蝕防止用転がり軸受の断面図である。It is sectional drawing of the rolling bearing for electrolytic corrosion prevention which concerns on other embodiment which formed the ceramic sprayed coating in the inner ring | wheel.
　以下に本発明の実施の形態を説明する。図１は本発明の一実施形態に係る電蝕防止用転がり軸受１の断面図である。電蝕防止用転がり軸受１は、転動体として玉を使った玉軸受であり、リング状の金属製の外輪２と、外輪２と同心状に配置されて相対回転自在とされたリング状の金属製の内輪３と、外輪２と内輪３間に配置されているリング状の保持器４と、保持器４に保持されている複数の転動体５とで主に構成されている。なお、本発明はこの実施形態に限定されず、他の形状、形式又は他の部材が設けられたあらゆる電蝕防止用転がり軸受に適用される。他の電蝕防止用転がり軸受としては、例えば円錐ころ軸受、円筒ころ軸受等が挙げられる。 Embodiments of the present invention will be described below. FIG. 1 is a cross-sectional view of a rolling bearing 1 for preventing electric corrosion according to an embodiment of the present invention. The rolling bearing 1 for preventing electric corrosion is a ball bearing using balls as rolling elements, and is a ring-shaped metal outer ring 2 and a ring-shaped metal that is arranged concentrically with the outer ring 2 and is relatively rotatable. The inner ring 3 is mainly composed of a made inner ring 3, a ring-shaped cage 4 arranged between the outer ring 2 and the inner ring 3, and a plurality of rolling elements 5 held by the cage 4. In addition, this invention is not limited to this embodiment, It applies to the rolling bearing for an electric corrosion prevention provided with another shape, a form, or another member. Examples of other electric corrosion prevention rolling bearings include a tapered roller bearing and a cylindrical roller bearing.
　外輪２の内周には、断面円弧状の外輪側軌道面２ａが形成され、外輪側軌道面２ａの両側に、外輪側小径部２ｂ等が形成されている。内輪３の外周には、断面円弧状の内輪側軌道面３ａが形成され、内輪側軌道面３ａの両側に、内輪側小径部３ｂ等が形成されている。保持器４は円周方向に複数のポケット部４ａを有しており、各ポケット部４ａに、金属製で球形状の転動体５が回転可能に保持されている。外輪２に対し内輪３が回転すると、外輪側軌道面２ａおよび内輪側軌道面３ａ上を複数の転動体５が転動し、転動体５は内輪３の回転方向と同方向へ移動する。複数の転動体５を保持する保持器４も転動体５と同方向へ移動する。 An outer ring side raceway surface 2a having a circular arc shape is formed on the inner periphery of the outer ring 2, and outer ring side small diameter portions 2b and the like are formed on both sides of the outer ring side raceway surface 2a. An inner ring side raceway surface 3a having a circular arc shape is formed on the outer periphery of the inner ring 3, and inner ring side small diameter portions 3b and the like are formed on both sides of the inner ring side raceway surface 3a. The cage 4 has a plurality of pocket portions 4a in the circumferential direction, and a metallic and spherical rolling element 5 is rotatably held in each pocket portion 4a. When the inner ring 3 rotates with respect to the outer ring 2, the plurality of rolling elements 5 roll on the outer ring side raceway surface 2 a and the inner ring side raceway surface 3 a, and the rolling element 5 moves in the same direction as the rotation direction of the inner ring 3. The cage 4 that holds the plurality of rolling elements 5 also moves in the same direction as the rolling elements 5.
　電蝕防止用転がり軸受１は、主に車両の電動モータ、発電機、電気機器の回転軸を支承する転がり軸受に適用され、電動モータ等で生じた電流が外輪２、転動体５、内輪３を伝って流れる場合に、電蝕防止用転がり軸受１に電蝕を生じないようにする転がり軸受である。電蝕防止用転がり軸受１を取り付けるための図示しないハウジングに、外輪２が接触した状態で固定される。ハウジングへの接触部分である外輪２の外表面２１の全体に電蝕防止機能が付与されている。外輪２の外表面２１の電気抵抗を高くすることで電蝕防止用転がり軸受１にスパークのような局所的な電流が流れにくくなり電蝕を防ぐことができる。 The electric corrosion prevention rolling bearing 1 is mainly applied to a rolling bearing that supports a rotating shaft of an electric motor, a generator, or an electric device of a vehicle, and current generated by the electric motor or the like generates an outer ring 2, a rolling element 5, an inner ring 3. It is a rolling bearing that prevents electric corrosion from occurring in the rolling bearing 1 for preventing electric corrosion when flowing through the shaft. The outer ring 2 is fixed in contact with a housing (not shown) for attaching the rolling bearing 1 for preventing electric corrosion. An electrolytic corrosion preventing function is imparted to the entire outer surface 21 of the outer ring 2 that is a contact portion with the housing. Increasing the electric resistance of the outer surface 21 of the outer ring 2 makes it difficult for a local current such as a spark to flow through the rolling bearing 1 for preventing electric corrosion, thereby preventing electric corrosion.
　このような電蝕防止のため、外輪２の外表面２１にはセラミックス溶射皮膜１０が形成されている。なお、本実施形態ではセラミックス溶射皮膜１０を外輪２に形成しているが、図２に示すように内輪３の外表面３１に同様のセラミックス溶射皮膜を形成してもよい。この場合には、内輪３の外表面３１が図示しない回転軸に接触する。溶射皮膜を形成するためのセラミックス材料として、一般に、Ａｌ２Ｏ３、ＭｇＯ、ＴｉＯ２、Ｃｒ２Ｏ３、ＺｒＯ２、ＨｆＯ２、ＳｉＯ２、Ｙ２Ｏ３、Ａｌ２Ｏ３・ＴｉＯ２、Ａｌ２Ｏ３・ＳｉＯ２、Ａｌ２Ｏ３・ＭｇＯなどが知られている。その中でも、本実施形態のセラミックス溶射皮膜１０を構成するセラミックスとして、アルミニウム酸化物やチタン酸化物等を主成分とする材料を用いることができる。より具体的には、グレイアルミナ（Ａｌ２Ｏ３、ＴｉＯ２）、アルミナ・イットリア（３Ａｌ２Ｏ３・５Ｙ２Ｏ３）、アルミナ・マグネシア（Ｍｇ・Ａｌ２Ｏ４）、アルミナ・シリカ（３Ａｌ２Ｏ３・２ＳｉＯ２）等を挙げることができる。特に、アルミニウム酸化物及びチタン酸化物を主成分とするグレイアルミナが好適である。 In order to prevent such electrolytic corrosion, a ceramic spray coating 10 is formed on the outer surface 21 of the outer ring 2. In this embodiment, the ceramic sprayed coating 10 is formed on the outer ring 2, but a similar ceramic sprayed coating may be formed on the outer surface 31 of the inner ring 3 as shown in FIG. In this case, the outer surface 31 of the inner ring 3 comes into contact with a rotating shaft (not shown). As ceramic materials for forming a thermal spray coating, generally, Al 2 O 3 , MgO, TiO 2 , Cr 2 O 3 , ZrO 2 , HfO 2 , SiO 2 , Y 2 O 3 , Al 2 O 3 .TiO 2 , Al 2 O 3 .SiO 2 , Al 2 O 3 .MgO, and the like are known. Among these, as a ceramic constituting the ceramic sprayed coating 10 of the present embodiment, a material mainly composed of aluminum oxide, titanium oxide, or the like can be used. More specifically, gray alumina (Al 2 O 3 , TiO 2 ), alumina yttria (3Al 2 O 3 · 5Y 2 O 3 ), alumina magnesia (Mg · Al 2 O 4 ), alumina · silica (3Al 2 O 3 · 2SiO 2 ). In particular, gray alumina mainly composed of aluminum oxide and titanium oxide is suitable.
　電蝕防止用のセラミックス溶射皮膜の材料として、絶縁破壊電圧及び体積抵抗率の高いホワイトアルミナ（Ａｌ２Ｏ３）が知られている。上記のグレイアルミナ（Ａｌ２Ｏ３、ＴｉＯ２）には、導電物質であるチタン酸化物が含有されており、グレイアルミナの体積抵抗率はホワイトアルミナよりも低く、絶縁破壊電圧もホワイトアルミナより小さい。グレイアルミナを選択する大きな理由として、この体積抵抗率の低さによる低絶縁性が挙げられる。また、成膜性をも向上させることができる。チタン酸化物（ＴｉＯ２）の融点はホワイトアルミナよりも低い。そのため、アルミニウム酸化物（Ａｌ２Ｏ３）が１００％である場合よりも、チタン酸化物（ＴｉＯ２）を含有させた方が、金属基材に対して付着し易く、均一な皮膜を形成しやすい。そのため、グレイアルミナを選択した場合の方が歩留まりがよく、製造コストを低減することができる。 White alumina (Al 2 O 3 ), which has a high dielectric breakdown voltage and a high volume resistivity, is known as a material for a ceramic spray coating for preventing electrolytic corrosion. The gray alumina (Al 2 O 3 , TiO 2 ) contains titanium oxide, which is a conductive material. Gray alumina has a lower volume resistivity than white alumina, and a dielectric breakdown voltage lower than that of white alumina. . A major reason for selecting gray alumina is low insulation due to the low volume resistivity. Moreover, the film formability can also be improved. The melting point of titanium oxide (TiO 2 ) is lower than that of white alumina. Therefore, the titanium oxide (TiO 2 ) is more easily adhered to the metal substrate than the case where the aluminum oxide (Al 2 O 3 ) is 100%, and a uniform film is formed. Cheap. Therefore, the yield is better when gray alumina is selected, and the manufacturing cost can be reduced.
　従って、セラミックス溶射皮膜の抵抗を制御するために材料成分やその割合を調整する必要があり、本実施形態ではアルミニウム酸化物及びチタン酸化物を主成分とする材料であるグレイアルミナが最も好適に用いられる。局所的な電流が流れにくくなる配合割合として、セラミックス溶射皮膜中のアルミニウム酸化物の含有率を６０重量％～９８重量％とし、チタン酸化物の含有率を２重量％～４０重量％とする。さらに好ましくは、アルミニウム酸化物の含有率が７０重量％～９０重量％であり、チタン酸化物の含有率が１０重量％～３０重量％である。これにより、セラミックス溶射皮膜１０の体積抵抗率を１０６Ωｃｍ～１０１３Ωｃｍに調整している。セラミックス溶射皮膜１０のより好ましい体積抵抗率の範囲は１０８Ωｃｍ～１０１０Ωｃｍである。 Therefore, it is necessary to adjust the material components and the ratio thereof in order to control the resistance of the ceramic sprayed coating. In this embodiment, gray alumina which is a material mainly composed of aluminum oxide and titanium oxide is most preferably used. It is done. As a blending ratio at which local current hardly flows, the content of aluminum oxide in the ceramic sprayed coating is set to 60 wt% to 98 wt%, and the content of titanium oxide is set to 2 wt% to 40 wt%. More preferably, the content of aluminum oxide is 70 to 90% by weight, and the content of titanium oxide is 10 to 30% by weight. As a result, the volume resistivity of the ceramic sprayed coating 10 is adjusted to 10 6 Ωcm to 10 13 Ωcm. A more preferable range of the volume resistivity of the ceramic sprayed coating 10 is 10 8 Ωcm to 10 10 Ωcm.
　セラミックス溶射皮膜中にチタン酸化物を比較的多く含有させるのは、体積抵抗率を１０６Ωｃｍ～１０１３Ωｃｍに調整して、あえて低い絶縁性を得るためである。比較的電気抵抗の低いチタン酸化物の含有率を最大で４０重量％とすることによって、所要の絶縁性能を維持しつつも電流を完全に遮断しないようにしている。このようにすることで、非常に大きな電圧が負荷されても局所的な電界集中が生じなくなる。従って、非常に大きな電圧の瞬間的な負荷が長期に渡って繰り返されても絶縁性能が損なわれず、電蝕防止用転がり軸受１の損傷が長期に渡って防止される。 The reason why a relatively large amount of titanium oxide is contained in the ceramic sprayed coating is that the volume resistivity is adjusted to 10 6 Ωcm to 10 13 Ωcm to obtain a low insulating property. By setting the content of titanium oxide having a relatively low electrical resistance to a maximum of 40% by weight, the current is not completely cut off while maintaining the required insulation performance. By doing so, local electric field concentration does not occur even when a very large voltage is applied. Therefore, even if a momentary load with a very large voltage is repeated for a long period of time, the insulation performance is not impaired, and damage to the electric corrosion prevention rolling bearing 1 is prevented for a long period of time.
　セラミックス溶射皮膜の膜厚を調整することも重要である。本実施形態の膜厚は５０μｍ～１００μｍとしており、従来よりも極めて薄いセラミックス溶射皮膜を形成している。膜厚のより好ましい範囲は７０μｍ～８５μｍである。外輪２又は内輪３の外表面２１、３１に形成するセラミックス溶射皮膜１０を極めて薄くすることで次のような利点がある。セラミックス溶射皮膜１０の成膜工程では、対象とする金属基材の被成膜面の全面にセラミックス粉末をくまなく吹き付ける工程に最も長い時間を要し、当然のことながら膜厚が厚くなるだけ、溶射時間も長くなる。膜厚を本実施系形態の程度まで薄くできれば、従来よりも成膜時間を大幅に短縮でき、製造コストの低減効果が極めて大きい。 It is also important to adjust the film thickness of the ceramic sprayed coating. The film thickness of this embodiment is 50 μm to 100 μm, and a ceramic sprayed coating that is extremely thinner than the conventional one is formed. A more preferable range of the film thickness is 70 μm to 85 μm. There are the following advantages by making the ceramic sprayed coating 10 formed on the outer surfaces 21 and 31 of the outer ring 2 or the inner ring 3 extremely thin. In the film-forming process of the ceramic sprayed coating 10, the longest time is required for the process of spraying the ceramic powder all over the film-forming surface of the target metal substrate, and as a matter of course, the film thickness increases. The spraying time also becomes longer. If the film thickness can be reduced to the extent of the present embodiment, the film formation time can be greatly shortened compared to the conventional case, and the effect of reducing the manufacturing cost is extremely large.
　さらに鉄道車両の電動モータ等の温度差が大きい使用環境下では、電蝕防止用転がり軸受１の外輪２又は内輪３と、セラミックス溶射皮膜１０との界面に強い剪断応力が生じる場合がある。剪断応力は、外輪２又は内輪３からセラミックス溶射皮膜１０を引きはがそうという力となり皮膜の剥離を招く。また、セラミックス溶射皮膜１０の内部には成膜時に発生する熱収縮による残留応力が存在し、その残留応力の影響により機械的強度が下がり耐衝撃性の低下を招く場合もある。 Furthermore, in a use environment where the temperature difference is large such as an electric motor of a railway vehicle, a strong shear stress may occur at the interface between the outer ring 2 or the inner ring 3 of the rolling bearing 1 for preventing electric corrosion and the ceramic sprayed coating 10. The shear stress acts as a force to peel the ceramic sprayed coating 10 from the outer ring 2 or the inner ring 3 and causes peeling of the coating. In addition, there is a residual stress due to thermal shrinkage that occurs during film formation inside the ceramic sprayed coating 10, and the mechanical strength may decrease due to the influence of the residual stress, leading to a decrease in impact resistance.
　これらの点に関し、本実施形態のセラミックス溶射皮膜１０の膜厚は５０μｍ～１００μｍとして極めて薄い皮膜となっており剪断応力が小さく、皮膜の剥離が生じ難い。また、成膜時の残留応力も小さいことから機械的強度の低下を招き難い。従って、皮膜の剥離や割れ等の損傷を起こさないようにすることができる。セラミックス溶射皮膜１０の膜厚の上限を１００μｍとした意義は以上のとおりであり、膜厚の下限を５０μｍとしたのは、これよりも薄い膜厚とすると絶縁性能を維持できないからである。なお、セラミックス溶射皮膜１０の膜厚を制御するには例えば成膜時間を調整すればよい。 Regarding these points, the film thickness of the ceramic sprayed coating 10 of the present embodiment is 50 μm to 100 μm, which is an extremely thin coating, so that the shear stress is small and the coating is hardly peeled off. In addition, since the residual stress at the time of film formation is small, it is difficult to cause a decrease in mechanical strength. Accordingly, damage such as peeling or cracking of the film can be prevented. The significance of setting the upper limit of the film thickness of the ceramic sprayed coating 10 to 100 μm is as described above, and the lower limit of the film thickness is set to 50 μm because the insulating performance cannot be maintained if the film thickness is smaller than this. In addition, what is necessary is just to adjust the film-forming time, for example, in order to control the film thickness of the ceramic sprayed coating 10. FIG.
　セラミックス溶射皮膜１０の表層には気孔を塞ぐための封孔処理が施されている。溶射皮膜は一般にその原理上、気孔を有しており、溶射皮膜が有する気孔の構造によっては、気体や液体が、被覆されている基材まで浸透する場合がある。封孔処理を施さなければ、気孔に例えば水が入り込んで絶縁性能を低下させる。封孔剤は、溶射層の気孔を封孔するばかりでなく、封孔処理後の皮膜の密着力を維持する働きも有する。本実施形態では、セラミックス溶射皮膜１０の気孔率を６％以下としている。セラミックス溶射皮膜１０の気孔率を６％よりも大きくすると、封孔剤が十分に充填されない場合があり、封孔剤の働きが発揮されなくなる。気孔率の制御はセラミックス粉末の粒度の調整の他、溶射ガンと被処理体である外輪２又は内輪３の外表面２１、３１との間の距離、溶射雰囲気の圧力の調整等によって行うことができる。 The surface layer of the ceramic sprayed coating 10 is subjected to a sealing treatment to close the pores. The thermal spray coating generally has pores in principle, and depending on the pore structure of the thermal spray coating, gas or liquid may permeate the coated substrate. If the sealing treatment is not performed, for example, water enters the pores and the insulating performance is lowered. The sealing agent not only seals the pores of the sprayed layer, but also has a function of maintaining the adhesion of the coating after the sealing treatment. In this embodiment, the porosity of the ceramic sprayed coating 10 is set to 6% or less. When the porosity of the ceramic sprayed coating 10 is larger than 6%, the sealing agent may not be sufficiently filled, and the function of the sealing agent cannot be exhibited. The porosity can be controlled by adjusting the particle size of the ceramic powder, adjusting the distance between the spray gun and the outer surfaces 21 and 31 of the outer ring 2 or inner ring 3 to be treated, and adjusting the pressure of the spraying atmosphere. it can.
　封孔処理用の有機系樹脂としては、セラミックス溶射皮膜１０の気孔に侵入できるような流動性のある樹脂であればよい。選択の際には、合成樹脂の平均分子量及び粘度が考慮される。合成樹脂には、例えばビスフェノールＦ型エポキシ樹脂、ビスフェノールＡ型エポキシ樹脂、ポリグリシジル（メタ）アクリレート等のエポキシ樹脂、アクリル樹脂、フッ素系樹脂、ウレタン樹脂、フェノール樹脂、キシレン樹脂、ポリエステル樹脂、不飽和ポリエステル樹脂、ポリアミド樹脂、メラミン樹脂など公知の合成樹脂を用いることができる。これらは、単独で又は２種以上を混合して用いることができる。 The organic resin for sealing treatment may be any resin that has fluidity so as to enter the pores of the ceramic sprayed coating 10. In the selection, the average molecular weight and viscosity of the synthetic resin are taken into consideration. Synthetic resins include, for example, bisphenol F type epoxy resin, bisphenol A type epoxy resin, epoxy resin such as polyglycidyl (meth) acrylate, acrylic resin, fluorine resin, urethane resin, phenol resin, xylene resin, polyester resin, unsaturated resin Known synthetic resins such as polyester resins, polyamide resins, and melamine resins can be used. These can be used alone or in admixture of two or more.
　セラミックス溶射皮膜１０は平均粒径が３μｍ～１５μｍのセラミックス粉末を溶射することによって形成されている。平均粒径が３μｍ～１５μｍのセラミックス粉末を溶射することで、溶射層の気孔率を６％以下に制御でき、気孔の大きさのばらつきを抑えることができる。本実施形態のように粒径が小さいセラミックス粉末を用いることにより、気孔が小さく、かつ気孔の大きさが均一なセラミックス溶射皮膜１０が得られる。気孔の大きさを均一にできれば、封孔剤の充填度合を良好にでき、絶縁性能のばらつきを抑える面から有利となる。 The ceramic spray coating 10 is formed by spraying ceramic powder having an average particle size of 3 μm to 15 μm. By spraying ceramic powder having an average particle size of 3 μm to 15 μm, the porosity of the sprayed layer can be controlled to 6% or less, and variation in pore size can be suppressed. By using a ceramic powder having a small particle diameter as in this embodiment, a ceramic sprayed coating 10 having small pores and uniform pore sizes can be obtained. If the pore size can be made uniform, the filling degree of the sealing agent can be improved, which is advantageous from the viewpoint of suppressing the variation in insulating performance.
　セラミックス粉末の平均粒径は小さいことが望ましいが、小さすぎると、溶射皮膜を形成する溶射工程でセラミックス粉末の流動性が低下して安定供給できないおそれがある。セラミックス粉末の搬送にむらができれば、皮膜強度にばらつきが生じやすく、厚みが不均一となり易い。このような観点から、平均粒径が３μｍ～１５μｍの範囲、より好ましくは３μｍ～１２μｍにあるセラミックス粉末を用いることが好ましい。セラミックス粉末の平均粒径が１５μｍを超えると、完全に溶融しないまま成膜される部分が生じてしまい、過度に多孔質化されて封孔剤の充填が難しくなり、絶縁性能が低下する。 The average particle size of the ceramic powder is desirably small, but if it is too small, the fluidity of the ceramic powder may decrease during the thermal spraying process for forming the thermal spray coating, and there is a possibility that it cannot be stably supplied. If the ceramic powder is unevenly conveyed, the coating strength tends to vary and the thickness tends to be non-uniform. From such a viewpoint, it is preferable to use a ceramic powder having an average particle diameter in the range of 3 μm to 15 μm, more preferably 3 μm to 12 μm. When the average particle size of the ceramic powder exceeds 15 μm, a portion where the film is formed without being completely melted is formed, and the portion becomes excessively porous so that it becomes difficult to fill the sealing agent, and the insulating performance is deteriorated.
　セラミックス溶射皮膜１０に有機系樹脂による封孔処理を施した後、研磨加工等の仕上げ処理を施し、表面粗さＲａが１μｍ未満、かつスキューネスＲｓｋが０未満となるように表面性状を制御している。 The ceramic sprayed coating 10 is subjected to a sealing treatment with an organic resin and then subjected to a finishing treatment such as polishing, and the surface properties are controlled so that the surface roughness Ra is less than 1 μm and the skewness Rsk is less than 0. Yes.
　セラミックス溶射皮膜１０の表面性状に関して、ＪＩＳＢ０６６０に規定する表面粗さＲａと、ＪＩＳＢ０６０１に規定されているスキューネスＲｓｋを指標としている。スキューネスＲｓｋは、基準長さにおける高さ偏差の三乗平均を二乗平均平方根の３乗で割った物理量である。スキューネスＲｓｋは表面の凹凸の差異を表現する数学的指標であり、対象となる面の凹凸の対称性を示す目安になる。スキューネスＲｓｋの値は、研磨後に表面に残留した少数の突起及び谷の存在に大きく影響される。スキューネスＲｓｋは、表面に鋭い突起が存在し、表面粗さの凸面積が大きい場合にはプラスの値になり、突起と谷が対称な場合には０に近づき、下に鋭く陥没する凹が多く、表面粗さの凹面積が大きい場合にはマイナスの値を示す。従って、表面粗さＲａを１μｍ未満、かつスキューネスＲｓｋを０未満とする電蝕防止用転がり軸受１の外輪２又は内輪３は、鋭い突起が極めて少ない表面性状を有している。 Regarding the surface properties of the ceramic sprayed coating 10, the surface roughness Ra defined in JISB0660 and the skewness Rsk defined in JISB0601 are used as indices. The skewness Rsk is a physical quantity obtained by dividing the cube average of the height deviation in the reference length by the cube of the root mean square. The skewness Rsk is a mathematical index that expresses the difference in surface irregularities, and serves as a standard indicating the symmetry of the irregularities on the target surface. The value of the skewness Rsk is greatly influenced by the presence of a small number of protrusions and valleys remaining on the surface after polishing. The skewness Rsk has a positive value when there are sharp protrusions on the surface and the convex area of the surface roughness is large, and approaches zero when the protrusions and valleys are symmetric. When the concave area of the surface roughness is large, a negative value is shown. Therefore, the outer ring 2 or the inner ring 3 of the rolling bearing 1 for preventing electric corrosion having a surface roughness Ra of less than 1 μm and a skewness Rsk of less than 0 has a surface property with very few sharp protrusions.
　表面性状を、溶射時のセラミックス粉末の粒径を調整することによって制御してもよい。セラミックス溶射皮膜１０は、熱源中にセラミック粉末を供給し、これを加熱して溶融させつつ外輪２又は内輪３の外表面２１、３１に吹き付け、溶融粒子を堆積させて得られる。セラミック粉末は数万個単位で、連続して熱源中へ供給され、結果的には扁平度の異なる粒子が無秩序に堆積する。研磨加工の他、本実施形態のように平均粒径が３μｍ～１５μｍの範囲のセラミック粉末を用いることによって、表面粗さＲａとスキューネスＲｓｋが上記の値を示すように制御することができる。さらに有機系樹脂による封孔処理を行うことによって表面粗さＲａとスキューネスＲｓｋが容易に上記の値を示すようになる。 The surface properties may be controlled by adjusting the particle size of the ceramic powder during spraying. The ceramic spray coating 10 is obtained by supplying ceramic powder into a heat source, spraying the ceramic powder on the outer surfaces 21 and 31 of the outer ring 2 or the inner ring 3 while heating and melting it, and depositing molten particles. The ceramic powder is supplied in units of tens of thousands of pieces continuously into the heat source. As a result, particles having different flatness are deposited randomly. In addition to polishing, the surface roughness Ra and skewness Rsk can be controlled to show the above values by using ceramic powder having an average particle size in the range of 3 μm to 15 μm as in this embodiment. Furthermore, the surface roughness Ra and the skewness Rsk can easily exhibit the above values by performing a sealing treatment with an organic resin.
　溶射皮膜の表面に突起が多ければ、電蝕防止用転がり軸受１に電流が流れようとしたときに、その突起に優先的に電圧がかかり、電界集中の箇所が点在することになる。本実施形態のように表面粗さＲａが１μｍ未満、かつスキューネスＲｓｋが０未満となる表面性状を有する外輪２又は内輪３とすることで、皮膜表面の鋭く尖った突起が少なくなり、表面上で生じる電界集中の点在を少なくでき、長期に渡る耐久性を向上させることができる。 If there are many protrusions on the surface of the thermal spray coating, when current flows through the rolling bearing 1 for preventing electric corrosion, voltage is preferentially applied to the protrusions, and electric field concentration points are scattered. By using the outer ring 2 or the inner ring 3 having the surface properties such that the surface roughness Ra is less than 1 μm and the skewness Rsk is less than 0 as in the present embodiment, sharp and sharp protrusions on the surface of the coating are reduced, and on the surface The scattered electric field concentration can be reduced, and durability over a long period can be improved.
　セラミックス溶射皮膜１０は、大気プラズマ溶射法、減圧プラズマ溶射法、高速フレーム溶射法、ガスフレーム溶射法、アーク溶射法、水プラズマ溶射法、電気アーク溶射法、爆発溶射法の何れかによって形成する。これら各種の溶射法を用いることによって、耐久性に優れ、かつ高品質のセラミックス溶射皮膜１０を得ることができる。各溶射法による成膜条件は、基材、原料粉末、膜厚、製造環境などに応じて適宜設定すればよい。 The ceramic sprayed coating 10 is formed by any one of the atmospheric plasma spraying method, the low pressure plasma spraying method, the high-speed flame spraying method, the gas flame spraying method, the arc spraying method, the water plasma spraying method, the electric arc spraying method, and the explosion spraying method. By using these various thermal spraying methods, it is possible to obtain a ceramic sprayed coating 10 having excellent durability and high quality. The film forming conditions by each thermal spraying method may be appropriately set according to the base material, raw material powder, film thickness, manufacturing environment, and the like.
　このうちプラズマ溶射法は、電気エネルギーを熱源とする溶射法であり、プラズマの発生源としてアルゴンや水素などを利用して成膜するものである。熱源温度が高く、フレーム速度が速いことから高融点のセラミックス材料を緻密に成膜することが可能であり、セラミックス溶射皮膜１０の製造方法に適している。 Among these, the plasma spraying method is a thermal spraying method using electric energy as a heat source, and forms a film using argon or hydrogen as a plasma generation source. Since the heat source temperature is high and the frame speed is high, a high melting point ceramic material can be densely formed, which is suitable for the method of manufacturing the ceramic sprayed coating 10.
　セラミックス溶射皮膜１０を得るための工程の一例を挙げると、基材である外輪２又は内輪３の外表面２１、３１の清浄化処理、外表面２１、３１のブラスト加工による粗面化処理、アンダーコート処理、トップコートであるセラミックス溶射皮膜１０の溶射、セラミックス溶射皮膜１０の表層の封孔処理、表面研磨処理をこの順に従って行う。溶射材料の違いによってアンダーコート処理が省かれることや、予熱工程などの他の工程が含まれる場合もある。 An example of a process for obtaining the ceramic sprayed coating 10 is to clean the outer surfaces 21 and 31 of the outer ring 2 or the inner ring 3 which is a base material, roughening the outer surfaces 21 and 31 by blasting, under The coating treatment, the thermal spraying of the ceramic sprayed coating 10 as the top coat, the sealing treatment of the surface layer of the ceramic sprayed coating 10, and the surface polishing treatment are performed in this order. The undercoat process may be omitted depending on the difference in the thermal spray material, and other processes such as a preheating process may be included.
　ブラスト加工の前に、外輪２又は内輪３の外表面２１、３１に付着している油脂、鉄さび等を、脱脂、酸洗、サンドブラスト処理などによって除去する。次いで、清浄化された外輪２又は内輪３の外表面２１、３１にＳｉＣ粒子やＡｌ２Ｏ３粒子等の硬質研削粒子を圧縮空気を駆動源としてブラスト加工を行い、表面粗さＲａが０．５μｍ～２．０μｍとなるように粗面化状態とする。後の溶射時において、溶融状態の微粒子が吹き付けられた際に粗面化された形状に沿って物理的に良好に噛み合うため、以上のように粗面化された外輪２又は内輪３の外表面２１、３１は溶射皮膜の密着力を上げるのに有効に作用する。アンダーコートは、外輪２又は内輪３の外表面２１、３１とセラミックス溶射皮膜１０との密着性を向上させ、皮膜の剥離や割れを防止する。 Prior to blasting, oil and fat, iron rust and the like adhering to the outer surfaces 21 and 31 of the outer ring 2 or the inner ring 3 are removed by degreasing, pickling, sand blasting, or the like. Next, the outer surfaces 21 and 31 of the cleaned outer ring 2 or inner ring 3 are blasted with hard abrasive particles such as SiC particles and Al 2 O 3 particles using compressed air as a driving source, and the surface roughness Ra is 0. The surface is roughened so as to be 5 μm to 2.0 μm. In the subsequent thermal spraying, the outer surface of the outer ring 2 or the inner ring 3 that has been roughened as described above, because the fine particles in the melted state physically mesh with each other along the roughened shape. 21 and 31 effectively act to increase the adhesion of the thermal spray coating. The undercoat improves the adhesion between the outer surfaces 21 and 31 of the outer ring 2 or the inner ring 3 and the ceramic sprayed coating 10 and prevents peeling or cracking of the coating.
　アンダーコートは必ずしも設ける必要はなく、セラミックス粉末を外輪２又は内輪３に直に溶射して成膜する場合には、セラミックス粉末が完全に溶融できるような溶射条件を採用すればよい。そのためには、セラミックス粉末の平均粒径を本実施形態のように３μｍ～１５μｍの範囲として、かつプラズマ熱源、及びプラズマ粒子の飛行速度等を適正化すればよい。 The undercoat is not necessarily provided, and when the ceramic powder is directly sprayed onto the outer ring 2 or the inner ring 3, the spraying conditions may be employed so that the ceramic powder can be completely melted. For this purpose, the average particle diameter of the ceramic powder may be in the range of 3 μm to 15 μm as in this embodiment, and the plasma heat source, the flight speed of the plasma particles, etc. may be optimized.
　以上説明したように電蝕防止用転がり軸受１の外輪２の外表面２１又は内輪３の外表面３１にセラミックス溶射皮膜１０が形成されているため、例えば鉄道車両用の電動モータの回転軸、発電機の回転軸に電圧が生じても、この回転軸を支持する当該転がり軸受１は電蝕防止効果を発揮できる。そして、外輪２又は内輪３の外表面２１、３１に、例えば３ｋＶ程度の高い電圧が長期間に渡って繰り返しかかっても、電蝕防止効果を維持し続けることができる。なお本実施形態では、電蝕防止用転がり軸受１の外輪２又は内輪３にセラミックス溶射皮膜１０を単層構造で設けるものとしたが、異なるセラミックス溶射皮膜を複層とすること、又はセラミックス溶射皮膜の上層に他の金属層を設けてもよい。 As described above, since the ceramic sprayed coating 10 is formed on the outer surface 21 of the outer ring 2 or the outer surface 31 of the inner ring 3 of the rolling bearing 1 for preventing electric corrosion, for example, a rotating shaft of an electric motor for a railway vehicle, power generation Even if a voltage is generated on the rotating shaft of the machine, the rolling bearing 1 that supports the rotating shaft can exhibit an electrolytic corrosion preventing effect. Even when a high voltage of, for example, about 3 kV is repeatedly applied to the outer surfaces 21 and 31 of the outer ring 2 or the inner ring 3 over a long period of time, it is possible to continue to maintain the electrolytic corrosion prevention effect. In the present embodiment, the ceramic sprayed coating 10 is provided in a single layer structure on the outer ring 2 or the inner ring 3 of the rolling bearing 1 for preventing electric corrosion. However, different ceramic sprayed coatings may be formed in multiple layers, or the ceramic sprayed coating. Another metal layer may be provided on the upper layer.
　上記本実施形態の電蝕防止用転がり軸受１によれば、セラミックス溶射皮膜１０の体積抵抗率が１０６Ωｃｍ～１０１３Ωｃｍとされており、絶縁性能を維持しつつも電流を完全に遮断しないので、非常に大きな電圧が負荷されても局所的な電界集中が生じなくなる。従って、非常に大きな電圧の瞬間的な負荷が長期に渡って繰り返されても絶縁性能が損なわれず、電蝕防止用転がり軸受１の損傷が防止される。これにより、耐久性を大幅に向上させることができる。 According to the rolling bearing 1 for preventing electric corrosion of the present embodiment, the volume resistivity of the ceramic sprayed coating 10 is set to 10 6 Ωcm to 10 13 Ωcm, and the current is not completely cut off while maintaining the insulation performance. Therefore, even when a very large voltage is applied, local electric field concentration does not occur. Therefore, even if a momentary load with a very large voltage is repeated for a long period of time, the insulation performance is not impaired, and damage to the electric corrosion prevention rolling bearing 1 is prevented. Thereby, durability can be improved significantly.
　以下、実施例により本発明をより詳細に説明する。本発明はこれら実施例に限定されるものではない。上記の実施形態に準じて金属基材の表面に、組成、膜厚、封孔処理、基材表面粗さ、成膜後表面粗さ、及び体積抵抗率を変えた試験片を製作して絶縁破壊性を評価した。絶縁破壊性の評価は絶縁破壊試験を実施し、絶縁破壊の有無を目視で確認して行った。 Hereinafter, the present invention will be described in more detail with reference to examples. The present invention is not limited to these examples. According to the above embodiment, a test piece having a composition, film thickness, sealing treatment, substrate surface roughness, post-film formation surface roughness, and volume resistivity is manufactured and insulated on the surface of the metal substrate. Destructibility was evaluated. The dielectric breakdown property was evaluated by conducting a dielectric breakdown test and visually confirming the presence or absence of dielectric breakdown.
　絶縁破壊試験法は次のとおりである。８０×８０ｍｍのアルミホイルを試験片の成膜している表面上の中央に置き、アルミホイルと試験片裏面の間に電圧を印加する。０ｋＶから序々に電圧を上げ、最大で３ｋＶまで印加して絶縁破壊（スパーク）の有無を確認する。耐電圧試験器として菊水電子工業（株）製のＴＯＳ－５１０１を用いた。 The dielectric breakdown test method is as follows. An 80 × 80 mm aluminum foil is placed in the center on the surface on which the test piece is formed, and a voltage is applied between the aluminum foil and the back side of the test piece. Gradually increase the voltage from 0 kV and apply up to 3 kV to confirm the presence or absence of dielectric breakdown (spark). As a withstand voltage tester, TOS-5101 manufactured by Kikusui Electronics Co., Ltd. was used.
　膜厚は、（株）ミツトヨ製の標準外側マイクロメータＭ１００を用いて測定し、表面粗さは、（株）東京精密サーフコム製の２８００Ｇを用いて測定した。体積抵抗率の測定方法は次のとおりである。８０×８０ｍｍのアルミホイルを試験片の成膜している表面上の中央に置き、アルミホイルと試験片裏面の間に電圧を印加する。その電圧をその際に流れた電流で割ることにより抵抗値Ｒを算出する。体積抵抗率ρは、面積Ｓ（８×８ｃｍ）、膜厚ｄ（ｃｍ）を用いて下記のように表される。体積抵抗率の測定に使用した装置は（株）ムサシインテック社製の直流耐電圧試験器ＩＰ－７０１Ｇである。
ρ＝Ｒ×（Ｓ／ｄ）　単位：Ωｃｍ The film thickness was measured using a standard outer micrometer M100 manufactured by Mitutoyo Corporation, and the surface roughness was measured using 2800G manufactured by Tokyo Seimitsu Surfcom. The volume resistivity measurement method is as follows. An 80 × 80 mm aluminum foil is placed in the center on the surface on which the test piece is formed, and a voltage is applied between the aluminum foil and the back side of the test piece. The resistance value R is calculated by dividing the voltage by the current flowing at that time. The volume resistivity ρ is expressed as follows using the area S (8 × 8 cm) and the film thickness d (cm). The apparatus used for measuring the volume resistivity is a DC withstanding voltage tester IP-701G manufactured by Musashi Intec Co., Ltd.
ρ = R × (S / d) Unit: Ωcm
　１００×１００×１０ｍｍのＳＳ４００製の平板の片面をまずブラスト加工によって粗面化処理し、その後セラミックス溶射を行い、成膜した表層に封孔処理を施し、最後に研磨仕上げを行って試験片を作製した。封孔処理無しの比較例では、セラミックス溶射の後、研磨仕上げを行った。粗面化処理はアルミナグリッドブラスト加工によって行い、封孔処理はエポキシ系封孔剤塗布後、焼成して行い、最後の研磨仕上げは平面研磨機を用いて行った。なお、実際の施工現場では、例えば筒状構造体の曲面等に皮膜を形成する場合があるのに対して、本実施例では平板状の試験片を用いて評価している。皮膜の体積抵抗率及び絶縁破壊電圧は基材の形状には殆ど影響されず、均一な条件を得やすい平板状の試験片で比較した方がより厳密な評価結果となるからである。 One side of a SS400 flat plate of 100 x 100 x 10 mm is first roughened by blasting, then ceramic spraying is performed, the surface layer on which the film is formed is subjected to sealing treatment, and finally polishing finish is performed to obtain a test piece. Produced. In the comparative example without sealing treatment, polishing finish was performed after ceramic spraying. The roughening treatment was performed by alumina grid blasting, the sealing treatment was performed by applying an epoxy sealant and then firing, and the final polishing finish was performed using a flat polishing machine. In an actual construction site, for example, a film may be formed on a curved surface of a cylindrical structure, for example. In this example, evaluation is performed using a flat test piece. This is because the volume resistivity and dielectric breakdown voltage of the film are hardly affected by the shape of the substrate, and a more rigorous evaluation result is obtained by comparing with a flat test piece that easily obtains uniform conditions.
　溶射条件は次のとおりである。溶射法：プラズマ溶射法、電流値：６００Ａ、アルゴンガス流量：４０ＮＬＰＭ、水素ガス流量：８．５ＮＬＰＭ、溶射距離：１００ｍｍ、ラダースキャン（ガン送り速度：６００ｍｍ／ｓｅｃ、３ｍｍピッチ）。 The thermal spraying conditions are as follows. Thermal spraying method: plasma spraying method, current value: 600 A, argon gas flow rate: 40 NLPM, hydrogen gas flow rate: 8.5 NLPM, spraying distance: 100 mm, ladder scan (gun feed rate: 600 mm / sec, 3 mm pitch).
　各実施例及び比較例の組成（チタニア含有率）、膜厚、封孔処理の有無、基材表面粗さ、成膜後表面粗さ、体積抵抗率及び絶縁破壊試験の結果を表１に示す。表１において、基材表面粗さとは、平板の片面をブラスト加工によって粗面化処理した後の粗さであり、成膜後の表面粗さとは、成膜した表層に封孔処理を施し、研磨仕上げを行った後の表面粗さでる。封孔処理無しの場合では、成膜した表面を研磨仕上げした後の表面粗さである。 Table 1 shows the composition (titania content), film thickness, presence / absence of sealing treatment, substrate surface roughness, post-film surface roughness, volume resistivity, and dielectric breakdown test results of each example and comparative example. . In Table 1, the substrate surface roughness is the roughness after roughening one side of a flat plate by blasting, and the surface roughness after film formation is to seal the formed surface layer, It is the surface roughness after polishing finish. In the case of no sealing treatment, it is the surface roughness after the film-formed surface is polished.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　実施例１～実施例７では、いずれも絶縁破壊（スパーク）は発生しなかった。比較例１では電流の漏れはなかったが抵抗が高すぎてスパークが生じた。比較例２及び３では抵抗が低すぎてアーキングを生じ、スパークが発生した。封孔処理なしの比較例４では大気中の水分を含みやすく、スパークし易い傾向が見られた。比較例５では膜厚が薄すぎてスパークが生じた。比較例６では密着性が低く成膜中に剥離した。比較例７及び８では基材の表面粗さが大きすぎてスパークが生じた。電界集中の発生が原因と考えられる。比較例９では成膜後の表面粗さが大きすぎてスパークが生じた。この場合も電界集中の発生が原因と考えられる。 In Examples 1 to 7, no dielectric breakdown (spark) occurred. In Comparative Example 1, there was no current leakage, but the resistance was too high and sparking occurred. In Comparative Examples 2 and 3, the resistance was too low, resulting in arcing and sparking. In Comparative Example 4 without sealing treatment, moisture in the atmosphere was likely to be contained, and a tendency to spark was observed. In Comparative Example 5, the film thickness was too thin and sparking occurred. In Comparative Example 6, the adhesion was low and the film was peeled off during film formation. In Comparative Examples 7 and 8, the surface roughness of the substrate was too large and sparks were generated. The cause is thought to be the occurrence of electric field concentration. In Comparative Example 9, the surface roughness after film formation was too large and sparking occurred. Also in this case, it is considered that the electric field concentration is caused.
　１　電蝕防止用転がり軸受
　２　外輪
　３　内輪
　５　転動体
　２１　外輪の外表面
　３１　内輪の外表面 DESCRIPTION OF SYMBOLS 1 Rolling bearing for electric corrosion prevention 2 Outer ring 3 Inner ring 5 Rolling element 21 Outer ring outer surface 31 Outer ring outer surface

Claims (7)

  1. 　金属製の外輪と、
    　この外輪と複数の転動体を介して同心状に配置されて相対回転自在とされた金属製の内輪と
    　前記外輪又は前記内輪の外表面に、プラズマ溶射法によって形成された電蝕防止用のセラミックス溶射皮膜と、を備え、
    　前記セラミックス溶射皮膜の体積抵抗率が１０６Ωｃｍ～１０１３Ωｃｍであることを特徴とする電蝕防止用転がり軸受。     A metal outer ring,
    A metal inner ring concentrically disposed through the outer ring and a plurality of rolling elements and relatively rotatable, and a ceramic for electrolytic corrosion prevention formed on the outer ring or the outer surface of the inner ring by a plasma spraying method A thermal spray coating,
    A rolling bearing for preventing electrolytic corrosion, wherein the ceramic sprayed coating has a volume resistivity of 10 6 Ωcm to 10 13 Ωcm.
  2. 　前記セラミックス溶射皮膜の膜厚が５０μｍ～１００μｍであることを特徴とする請求項１に記載の電蝕防止用転がり軸受。 2. The rolling bearing for preventing electric corrosion according to claim 1, wherein the ceramic sprayed coating has a thickness of 50 μm to 100 μm.
  3. 　前記セラミックス溶射皮膜は、アルミニウム酸化物及びチタン酸化物を主成分とする材料からなり、アルミニウム酸化物の含有率は６０重量％～９８重量％とされると共にチタン酸化物の含有率は２重量％～４０重量％であることを特徴とする請求項１又は２に記載の電蝕防止用転がり軸受。 The ceramic sprayed coating is made of a material mainly composed of aluminum oxide and titanium oxide. The content of aluminum oxide is 60% by weight to 98% by weight and the content of titanium oxide is 2% by weight. The rolling bearing for preventing electrolytic corrosion according to claim 1 or 2, characterized in that it is -40 wt%.
  4. 　前記セラミックス溶射皮膜に有機系樹脂による封孔処理が施されていることを特徴とする請求項１～３のいずれかに記載の電蝕防止用転がり軸受。 The rolling bearing for preventing electrolytic corrosion according to any one of claims 1 to 3, wherein the ceramic sprayed coating is sealed with an organic resin.
  5. 　封孔処理後に施される仕上げ処理後の表面粗さＲａが１μｍ未満であり、かつスキューネスＲｓｋが０未満であることを特徴とする請求項４に記載の電蝕防止用転がり軸受。 5. The rolling bearing for preventing corrosion according to claim 4, wherein the surface roughness Ra after finishing treatment applied after the sealing treatment is less than 1 μm and the skewness Rsk is less than 0.
  6. 　前記セラミックス溶射皮膜で被覆されている前記外輪又は前記内輪の溶射前の外表面の表面粗さＲａが０．５μｍ～２．０μｍであることを特徴とする請求項１～５のいずれかに記載の電蝕防止用転がり軸受。 6. The surface roughness Ra of the outer surface of the outer ring or the inner ring coated with the ceramic spray coating before spraying is 0.5 μm to 2.0 μm, according to any one of claims 1 to 5. Rolling bearing for preventing electric corrosion.
  7. 　前記セラミックス溶射皮膜は、平均粒径：３μｍ～１５μｍの粉末を原料として形成されていることを特徴とする請求項１～６のいずれかに記載の電蝕防止用転がり軸受。 7. The rolling bearing for preventing electric corrosion according to claim 1, wherein the ceramic sprayed coating is formed using a powder having an average particle diameter of 3 μm to 15 μm as a raw material.
PCT/JP2014/050048 2013-03-28 2014-01-07 Rolling bearing for electric corrosion prevention WO2014156206A1 (en)

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