WO2017099071A1 - 軸受用軸及び軸受 - Google Patents
軸受用軸及び軸受 Download PDFInfo
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- WO2017099071A1 WO2017099071A1 PCT/JP2016/086215 JP2016086215W WO2017099071A1 WO 2017099071 A1 WO2017099071 A1 WO 2017099071A1 JP 2016086215 W JP2016086215 W JP 2016086215W WO 2017099071 A1 WO2017099071 A1 WO 2017099071A1
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- bearing
- bearing shaft
- nitrogen
- shaft
- rolling element
- Prior art date
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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
- F16C3/00—Shafts; Axles; Cranks; Eccentrics
- F16C3/02—Shafts; Axles
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/40—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for rings; for bearing races
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
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- 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
- C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
- C23C8/06—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases
- C23C8/28—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases more than one element being applied in one step
- C23C8/30—Carbo-nitriding
- C23C8/32—Carbo-nitriding of ferrous surfaces
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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
- F16C33/34—Rollers; Needles
- F16C33/36—Rollers; Needles with bearing-surfaces other than cylindrical, e.g. tapered; with grooves in the bearing surfaces
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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
- F16C33/46—Cages for rollers or needles
- F16C33/54—Cages for rollers or needles made from wire, strips, or sheet metal
- F16C33/542—Cages for rollers or needles made from wire, strips, or sheet metal made from sheet metal
- F16C33/543—Cages for rollers or needles made from wire, strips, or sheet metal made from sheet metal from a single part
- F16C33/546—Cages for rollers or needles made from wire, strips, or sheet metal made from sheet metal from a single part with a M- or W-shaped cross section
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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
- F16C33/583—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
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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
- F16C33/62—Selection of substances
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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
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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
- F16C33/66—Special parts or details in view of lubrication
- F16C33/6637—Special parts or details in view of lubrication with liquid lubricant
- F16C33/6659—Details of supply of the liquid to the bearing, e.g. passages or nozzles
- F16C33/6677—Details of supply of the liquid to the bearing, e.g. passages or nozzles from radial inside, e.g. via a passage through the shaft and/or inner ring
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/06—Surface hardening
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/18—Hardening; Quenching with or without subsequent tempering
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/001—Austenite
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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
- F16C2361/00—Apparatus or articles in engineering in general
- F16C2361/61—Toothed gear systems, e.g. support of pinion shafts
Definitions
- the present invention relates to a bearing shaft and a bearing, and more particularly to a bearing shaft used for a bearing used in a manner of rotating an outer ring.
- bearings used in mechanical devices such as planetary gear reducers are known.
- Such a bearing is used in a manner of rotating the outer ring.
- the bearing shaft located on the inner ring side always has the same load region, so that there is a problem that the life is shortened with respect to fatigue peeling.
- a bearing shaft is made of an alloy steel containing 0.1 to 0.5% by mass of carbon and other alloy elements, and the bearing shaft is used.
- a technique is disclosed in which a hardened layer is formed on the surface of a shaft for a bearing by performing a shot peening treatment after subjecting the shaft to carbonitriding, induction hardening, and tempering.
- the bearing shaft described above is used in the most severe state with respect to fatigue peeling, so the life of the bearing shaft restricts the life of the entire mechanical device. Therefore, further improvement in durability is required for the bearing shaft.
- the present invention has been made to solve the above-described problems, and an object of the present invention is to provide a bearing shaft and a bearing excellent in durability.
- the bearing shaft according to the present invention is a bearing shaft having an outer peripheral surface including a raceway surface with which a rolling element contacts, and is made of steel containing 0.7% or more of carbon.
- a nitrogen-enriched layer is formed on the raceway surface.
- the absolute value of the compressive residual stress on the surface of the nitrogen-enriched layer is 600 MPa or more and 1700 MPa or less.
- a bearing according to the present invention includes a bearing shaft including an outer peripheral surface having a raceway surface, and a rolling element including a surface in contact with the raceway surface.
- the bearing shaft is made of steel containing 0.7% or more of carbon.
- a nitrogen-enriched layer is formed on the raceway surface.
- the absolute value of the compressive residual stress on the surface of the nitrogen-enriched layer is 600 MPa or more and 1700 MPa or less, and the amount of retained austenite at the surface layer portion on the surface of the rolling element is the amount of the nitrogen-enriched layer formed on the raceway surface of the bearing shaft. More than the amount of retained austenite in the surface layer.
- the life of the bearing shaft can be extended.
- FIG. 4 is a partial cross-sectional schematic diagram showing a modification of the needle roller shown in FIG. 3.
- FIG. 6 is a partial cross-sectional schematic diagram showing a modification of the cage shown in FIG. 4.
- FIG. 9 is a schematic cross-sectional view taken along line IX-IX in FIG.
- FIG. 1 is a schematic cross-sectional view of a bearing according to an embodiment. With reference to FIG. 1, the structure of the bearing according to embodiment is demonstrated.
- the bearing 10 includes a bearing shaft 1, rolling elements 2 that are needle rollers, and a cage 3.
- the bearing shaft 1 has a cylindrical shape.
- a plurality of rolling elements 2 are arranged on a side surface that is a raceway surface of the bearing shaft 1.
- the plurality of rolling elements 2 are arranged on the side surface of the bearing shaft 1 at intervals in the circumferential direction.
- the plurality of rolling elements 2 are arranged at equal intervals on the side surface of the bearing shaft 1.
- the bearing shaft 1 is made of steel containing 0.7% or more of carbon.
- a nitrogen-enriched layer 1a is formed on the raceway surface.
- the nitrogen enriched layer 1a has a higher nitrogen concentration than the inner peripheral portion 1c of the bearing shaft 1.
- a hardened layer 1b is formed on the surface of the nitrogen-enriched layer 1a.
- the absolute value of the compressive residual stress on the surface of the nitrogen-enriched layer 1a (that is, the surface of the hardened layer 1b) is 600 MPa or more and 1700 MPa or less.
- the cage 3 is disposed on the side surface of the bearing shaft 1 and has an annular shape along the circumferential direction of the side surface.
- the cage 3 is formed with a plurality of pockets for holding the rolling elements 2 inside. When the rolling element 2 is accommodated in the pocket, the position of the rolling element 2 is determined.
- FIG. 2 is a schematic cross-sectional view of a bearing shaft constituting the bearing shown in FIG. With reference to FIG. 2, the structure of the bearing shaft 1 will be described in detail.
- a nitrogen-enriched layer 1a is formed on the surface of the bearing shaft 1 (the side surface as the raceway surface and the end surface extending so as to intersect the side surface).
- a hardened layer 1b is formed on the surface of the nitrogen-enriched layer 1a.
- the hardened layer 1b is formed by performing shot peening. As described above, the absolute value of the compressive residual stress on the surface of the hardened layer 1b is 600 MPa or more and 1700 MPa or less.
- the hardness on the surface of the cured layer 1b is Hv850 or more and Hv1000 or less. Moreover, the surface roughness of the hardened layer 1b is 0.2 micrometer or less by arithmetic mean roughness Ra. Furthermore, the amount of retained austenite in the hardened layer 1b is 9% by volume or less.
- the bearing shaft 1 is made of, for example, high carbon chrome bearing steel.
- FIG. 3 is a schematic cross-sectional view of the rolling element 2 constituting the bearing shown in FIG. With reference to FIG. 3, the structure of the rolling element 2 is demonstrated concretely.
- the rolling element 2 is a needle roller, and a nitrogen-enriched layer 2 a is formed on the surface (a side surface in contact with the bearing shaft 1 and an end surface extending in a direction intersecting the side surface). Yes.
- the nitrogen enriched layer 2 a has a higher nitrogen concentration than the inner peripheral portion 2 c of the rolling element 2.
- the amount of retained austenite at the surface layer portion on the surface of the rolling element is larger than the amount of retained austenite at the surface layer portion of the nitrogen-enriched layer formed on the raceway surface of the bearing shaft.
- the amount of retained austenite at the surface layer portion on the surface of the rolling element is 9% by volume or more and 50% by volume or less.
- the amount of retained austenite may exceed 9% by volume.
- FIG. 4 is a partial cross-sectional schematic view showing a cage constituting the bearing shown in FIG. The retainer 3 will be described with reference to FIG.
- the cage 3 has an annular shape as described above.
- the cage 3 is formed with a plurality of pockets 3a for holding the rolling elements 2 (see FIG. 1) inside.
- the pockets 3a are formed at substantially equal intervals.
- Any material can be used as the material of the cage 3.
- a material constituting the cage 3 for example, steel can be used.
- the cage 3 may be formed by pressing the steel. Further, a resin may be used as a material constituting the cage 3.
- ⁇ Manufacturing method> As a manufacturing method of the bearing 10, first, members (bearing shaft 1, rolling element 2, cage 3) constituting the bearing 10 are prepared as follows. And the bearing 10 can be obtained by implementing the process of assembling the said member.
- Manufacturing method of shaft 1 for bearing As a manufacturing method of the bearing shaft 1 described above, first, a rod-shaped material (for example, a material made of JIS standard SUJ2) is prepared from steel having a composition constituting the bearing shaft 1. And the said raw material is processed into the shape of the shaft 1 for bearings by applying conventionally well-known machining processes, such as turning, with respect to the said raw material (machining process). Thereafter, a heat treatment step is performed. Specifically, carbonitriding, tempering, quenching, and tempering are performed on the material processed as described above. As a specific example of conditions for the heat treatment, for example, a temperature condition such as 800 ° C. or higher and lower than 1000 ° C. that is a temperature of the A1 point or higher can be used for the carbonitriding treatment temperature.
- a temperature condition such as 800 ° C. or higher and lower than 1000 ° C. that is a temperature of the A1 point or higher can be used for the carbonitriding treatment temperature.
- the heat-treated material is subjected to conventionally known machining such as grinding to finish the material so as to have the dimensions of the bearing shaft 1.
- shot peening is performed on the side surface (side surface to be the rolling surface) of the bearing shaft 1. In this way, the bearing shaft 1 can be obtained.
- the order of the finishing process and the shot peening process described above may be changed, and the shot peening process may be performed first.
- Manufacturing method of rolling element 2 As a manufacturing method of the rolling element 2, a conventionally well-known manufacturing method can be used. For example, a rod-shaped material made of steel (for example, high carbon chromium bearing steel) is prepared as the rolling element 2. The material is processed so as to be in the shape of the rolling element 2 by performing conventionally known machining on the material. Thereafter, a heat treatment step is performed. Specifically, carbonitriding is performed on the material processed as described above. As a specific example of conditions for the heat treatment, for example, a temperature condition such as 800 ° C. or higher and lower than 1000 ° C. that is a temperature of the A1 point or higher can be used for the carbonitriding treatment temperature.
- a temperature condition such as 800 ° C. or higher and lower than 1000 ° C. that is a temperature of the A1 point or higher can be used for the carbonitriding treatment temperature.
- the heat-treated material is subjected to conventionally known machining such as grinding to process the material so as to have the dimensions of the rolling element 2. In this way, the rolling element 2 can be obtained.
- Manufacturing method of cage 3 As a manufacturing method of the cage 3, a conventionally known manufacturing method can be used.
- the bearing shaft 1 is a bearing shaft 1 including an outer peripheral surface including a raceway surface (side surface) with which the rolling element 2 contacts as described above, and steel containing 0.7% or more of carbon. It is comprised by.
- a nitrogen-enriched layer 1a is formed on the raceway surface.
- the absolute value of the compressive residual stress on the surface of the nitrogen-enriched layer 1a (the surface of the hardened layer 1b formed by shot peening on the side surface of the bearing shaft 1) is 600 MPa or more and 1700 MPa or less.
- the bearing 10 includes a bearing shaft 1 including an outer peripheral surface having a raceway surface, and a rolling element 2 including a surface in contact with the raceway surface.
- the bearing shaft 1 is made of steel containing 0.7% or more of carbon.
- a nitrogen-enriched layer 1a is formed on the raceway surface.
- the absolute value of the compressive residual stress on the surface of the nitrogen-enriched layer 1a (the surface of the hardened layer 1b) is 600 MPa to 1700 MPa.
- the lower limit of the absolute value of the compressive residual stress may be 1000 MPa. In this case, the resistance to fatigue described above can be clearly increased (for example, the life related to fatigue peeling can be made longer than before).
- the lower limit value of the absolute value of the compressive residual stress may be 1300 MPa. In this case, the bearing strength against fatigue of the bearing shaft 1 can be reliably improved.
- the amount of retained austenite in the surface layer portion (nitrogen-enriched layer 2a) on the surface of the rolling element 2 is the surface layer portion (hardened layer 1b) of the nitrogen-enriched layer 1a formed on the raceway surface of the bearing shaft 1. It may be larger than the amount of retained austenite in).
- a measurement method by X-ray diffraction can be used as a method for measuring the amount of retained austenite.
- the amount of retained austenite of the rolling element 2 is larger than the amount of retained austenite in the surface layer portion (hardened layer 1 b) of the bearing shaft 1, there is a foreign matter between the raceway surface of the bearing shaft 1 and the rolling element 2. Even when it is bitten, the surface of the rolling element 2 can be deformed by the foreign matter. For this reason, it is possible to reduce the possibility that a damaged portion such as a scratch or a crack is generated on the bearing shaft 1 side due to the presence of the foreign matter.
- the amount of retained austenite at the surface layer portion (nitrogen-enriched layer 2a) on the surface of the rolling element 2 may be 9% by volume or more and 50% by volume or less.
- the upper limit of the amount of retained austenite in the surface layer portion of the rolling element 2 is set to 50% by volume. When the upper limit is exceeded, the dimensional change caused by the transformation of the crystal structure during use may affect the characteristics of the bearing 10. This is because of the increase.
- the upper limit of the amount of retained austenite at the surface layer of the rolling element 2 may be 30% by volume. In this case, the influence of the dimensional change due to the transformation of the crystal structure can be further reduced. Further, the lower limit of the amount of retained austenite at the surface layer portion of the rolling element 2 may be 15% by volume. In this case, since the deformation due to the foreign matter can be easily caused on the rolling element 2 side when the foreign matter is caught, the possibility that the foreign matter is damaged in the bearing shaft 1 can be further reduced.
- the nitrogen enriched layer 2a is formed on the surface of the rolling element 2 as described above.
- the fatigue strength and wear resistance of the rolling element 2 can be improved.
- the nitrogen-enriched layer 2a is a layer in which the nitrogen concentration in the steel is increased with respect to the nitrogen concentration contained in the material steel.
- the hardness (Vickers hardness) of the surface of the nitrogen-enriched layer 1a formed on the raceway surface (side surface) (surface of the hardened layer 1b) is Hv850 or higher and Hv1000 or lower.
- the hardness of the surface of the hardened layer 1b is sufficiently high, it is possible to suppress the occurrence of indentations and the like in the bearing shaft 1 due to the biting of foreign matter. For this reason, it is possible to enhance the durability against fatigue peeling in the bearing shaft 1 under a foreign matter mixing condition.
- the surface roughness of the nitrogen-enriched layer 1a formed on the raceway surface (side surface) is 0.2 ⁇ m or less in terms of arithmetic average roughness Ra.
- the surface roughness of the surface of the bearing shaft 1 is large. It is possible to suppress the occurrence of a problem that the surface cannot be used as a raceway surface.
- the upper limit of the surface roughness of the nitrogen-enriched layer 1a may be 0.05 ⁇ m in terms of arithmetic average roughness Ra. In this case, the rolling element brought into contact with the surface of the bearing shaft can be smoothly rolled.
- the upper limit of the surface roughness of the nitrogen-enriched layer may be an arithmetic average roughness Ra of 0.03 ⁇ m.
- the amount of retained austenite in the surface layer portion (hardened layer 1b) of the nitrogen-enriched layer 1a formed on the raceway surface (side surface) is 9% by volume or less.
- the amount of retained austenite in the surface layer portion (cured layer 1b) is kept low, the hardness and strength in the surface layer portion (cured layer 1b) constituting the raceway surface can be sufficiently increased.
- the amount of retained austenite in the surface layer portion (cured layer 1b) may be 5% by volume or less, or 3% by volume or less.
- the steel constituting the bearing shaft 1 is high-carbon chromium bearing steel. In this case, sufficiently high hardness and strength can be obtained also for the inner peripheral portion 1 c of the bearing shaft 1.
- FIG. 5 is a schematic cross-sectional view showing a modification of the bearing shaft 1 shown in FIG.
- the modification of the bearing shaft 1 basically has the same configuration as the bearing shaft 1 shown in FIG. 2 and can obtain the same effect.
- An oil hole 21 extending from the end face of the bearing shaft 1 along the central axis of the bearing shaft 1 and a branch hole 22 connected to the oil hole 21 in the bearing shaft 1 and extending in the radial direction of the bearing shaft 1 are formed. This is different from the bearing shaft 1 shown in FIG.
- the end of the branch hole 22 reaches the side surface of the bearing shaft 1 (the raceway surface in contact with the rolling element 2) and is connected to an opening formed on the side surface.
- the oil hole 21 and the branch hole 22 By forming the oil hole 21 and the branch hole 22, the lubricating oil can be easily supplied to the contact portion between the bearing shaft 1 and the rolling element 2 through the oil hole 21 and the branch hole 22.
- the oil hole 21 may be provided so as to penetrate the bearing shaft 1 in the central axis direction.
- FIG. 6 is a partial cross-sectional schematic diagram showing a modification of the rolling element 2 shown in FIG.
- the modified example of the rolling element 2 basically has the same configuration as the rolling element 2 shown in FIG. 3 and can obtain the same effect.
- 3 is different from the rolling element 2 shown in FIG. 3 in that crowning 2d is formed at both ends in the axial direction. That is, in the bearing 10, the rolling element 2 is a roller with crowning.
- the contact surface pressure at the contact portion between the bearing shaft 1 and the rolling element 2 at the end of the rolling element 2 can be prevented from locally increasing. As a result, the occurrence of defects such as peeling in the bearing shaft 1 can be suppressed.
- any form can be adopted as the shape of the crowning of the rolling element 2, for example, logarithmic crowning can be applied.
- FIG. 7 is a partial cross-sectional schematic diagram showing a modified example of the cage 3 shown in FIG.
- the modified example of the cage 3 basically has the same configuration as the cage 3 shown in FIG. 4, but is held outside the central axis of the rolling element 2 held in the pocket.
- the cage 3 shown in FIG. 4 is configured such that the structure of the vessel 3 (a column portion positioned between two adjacent pockets and extending along the central axis of the rolling element 2) is arranged. Is different.
- the cage 3 shown in FIG. 7 has a smaller distance between adjacent pockets than the cage 3 shown in FIG. More than the cage 3 shown in FIG. For this reason, the rated load of the bearing 10 can be increased compared with the case where the cage shown in FIG. 4 is used.
- FIG. 8 is a schematic diagram showing a planetary gear speed reducer (also referred to as a planetary speed reducer) to which the bearing shaft 1 or the bearing 10 according to the embodiment is applied.
- FIG. 9 is a partial cross-sectional schematic view taken along line IX-IX in FIG.
- the planetary gear speed reducer to which the bearing shaft 1 or the bearing 10 according to the embodiment is applied includes an input shaft 11 and a sun gear 12 that is coaxially attached to the input shaft 11.
- the internal gear 13 fixed concentrically to the reduction gear casing (not shown) on the outer diameter side of the sun gear 12, and the sun gear 12 and the internal gear 13 are interposed between the gears at equal intervals in the circumferential direction.
- a plurality of planetary gears 14 (in the illustrated case, at four positions shifted in the circumferential direction by about 90 ° when viewed from the input shaft 11) and bearings as planetary pins that support the rotation of each planetary gear 14
- the shaft 1 is composed of an annular carrier 16 in which all bearing shafts 1 are rotatably connected, and an output shaft 17 that is concentric with the carrier 16 and provided integrally therewith.
- a rolling element 2 (needle roller) is disposed between the planetary gear 14 and a bearing shaft 1 as a planetary pin that supports the planetary gear 14.
- the bearing shaft 1 is the bearing shaft 1 according to the embodiment, and a nitrogen-enriched layer 1a (see FIG. 1) and a hardened layer 1b (see FIG. 1) are provided on the side surface (track surface) that contacts the rolling element 2. Is formed.
- the rolling element 2 has the same configuration as the rolling element 2 shown in FIG.
- the bearing shaft 1 is formed to have a length protruding on both sides of the planetary gear 14.
- One of the portions of the bearing shaft 1 protruding from the end face of the planetary gear 14 is a protrusion 19 and the other is a protrusion 20.
- An oil hole 21 is provided in a penetrating state in the shaft center of the bearing shaft 1.
- a branch hole 22 is provided so as to be orthogonal to the oil hole 21 at an intersection 23 which is an intermediate part of the oil hole 21. Both end portions of the branch hole 22 are connected to openings on the side surface (outer diameter surface) of the bearing shaft 1.
- the protruding portion 19 described above is fitted and fixed to the carrier 16 with a sliding bearing 28 (side washer) interposed between the protruding portion 19 and the planetary gear 14. Further, the other protruding portion 20 is also fitted and fixed to the retaining member 27 with the planetary gear 14 interposed through a sliding bearing 28.
- the retaining member 27 may be an individual member for each bearing shaft 1 of each planetary gear 14, or may be an annular member similar to the carrier 16. Alternatively, the retaining member 27 may be integrated with the carrier 16.
- the bearing shaft 1 can be improved in resistance to fatigue, and the life of the bearing shaft 1 can be extended. Can be planned. As a result, it is possible to avoid the life of the planetary speed reducer being restricted by the bearing shaft 1.
- An oil bath lubrication system can be adopted as a lubrication system for the planetary gear reducer described above.
- the speed reducer is substantially immersed in the lubricating oil to the vicinity of its center (see the oil level L of the lubricating oil in FIG. 8).
- the planetary gear 14 rotates and revolves around the point P in the direction indicated by the arrow X in FIG.
- the oil that has flowed into the oil hole 21 when in the oil is supplied to the contact portion between the rolling element 2 and the bearing shaft 1 through the branch hole 22.
- the planetary gear reducer described above may be integrated with a drive unit such as a motor.
- a drive unit such as a motor.
- a drive unit having an arbitrary configuration can be used.
- a hydraulic motor such as a conductive motor or a swash plate motor can be used.
- the planetary gear speed reducer according to the embodiment may be applied to a drive unit that drives a caterpillar of a construction machine, for example.
- the bearing shaft 1 in which the oil hole 21 and the branch hole 22 are not formed may be applied as the bearing shaft 1.
- the embodiment is particularly advantageously applied to a bearing shaft such as a planetary gear reducer.
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Abstract
Description
図1は、実施形態に従った軸受の断面模式図である。図1を参照して、実施形態に従った軸受の構成を説明する。
図2は、図1に示した軸受を構成する軸受用軸の断面模式図である。図2を参照して、軸受用軸1の構成を具体的に説明する。
図3は、図1に示した軸受を構成する転動体2の断面模式図である。図3を参照して、転動体2の構成を具体的に説明する。
図4は、図1に示した軸受を構成する保持器を示す部分断面模式図である。図4を参照して、保持器3を説明する。
軸受10の製造方法としては、まず軸受10を構成する部材(軸受用軸1、転動体2、保持器3)を以下のように準備する。そして、当該部材を組立てる工程を実施することにより、軸受10を得ることができる。
上述した軸受用軸1の製造方法としては、まず軸受用軸1を構成する組成の鋼により棒状の素材(たとえばJIS規格SUJ2からなる素材)を準備する。そして、当該素材に対して旋削加工など従来周知の機械加工工程を適用することで、軸受用軸1の形状に当該素材を加工する(機械加工工程)。その後、熱処理工程を実施する。具体的には、上記のように加工された素材に対して浸炭窒化処理、調質処理、焼入処理、焼戻し処理などを実施する。熱処理の具体的な条件例としては、たとえば、浸炭窒化処理の処理温度について、A1点以上の温度である800℃以上1000℃未満といった温度条件を用いることができる。
転動体2の製造方法としては、従来周知の製造方法を用いることができる。たとえば、転動体2として鋼(たとえば高炭素クロム軸受鋼)からなる棒状の素材を準備する。当該素材に対して従来周知の機械加工を行うことにより、転動体2の形状となるよう当該素材を加工する。その後、熱処理工程を実施する。具体的には、上記のように加工された素材に対して浸炭窒化処理などを実施する。熱処理の具体的な条件例としては、たとえば、浸炭窒化処理の処理温度について、A1点以上の温度である800℃以上1000℃未満といった温度条件を用いることができる。
保持器3の製造方法としては、従来周知の製造方法を用いることができる。
実施形態に従った軸受用軸1は、上述のように転動体2が接触する軌道面(側面)を含む外周面を備える軸受用軸1であって、炭素を0.7%以上含有する鋼により構成されている。軌道面には、窒素富化層1aが形成されている。窒素富化層1aの表面(軸受用軸1の側面におけるショットピーニングにより形成された硬化層1bの表面)における圧縮残留応力の絶対値は600MPa以上1700MPa以下である。
図5は、図2に示した軸受用軸1の変形例を示す断面模式図である。図5に示すように、軸受用軸1の変形例は、基本的には図2に示した軸受用軸1と同様の構成を備え、同様の効果を得ることができるが、軸受用軸1の端面から軸受用軸1の中心軸に沿って延びる油穴21と、軸受用軸1の内部において当該油穴21に接続されるとともに軸受用軸1の径方向に延びる分岐穴22とが形成されている点が図2に示した軸受用軸1と異なっている。分岐穴22の端部は軸受用軸1の側面(転動体2と接触する軌道面)に到達し、当該側面に形成された開口部に繋がっている。このような油穴21および分岐穴22が形成されることにより、油穴21および分岐穴22を介して軸受用軸1と転動体2との接触部に潤滑油を容易に供給することができる。油穴21は、軸受用軸1を中心軸方向に貫通するように設けられていてもよい。
図8は、実施形態に係る軸受用軸1または軸受10を適用した遊星歯車減速機(遊星減速機とも呼ぶ)を示す模式図である。図9は、図8の線分IX-IXにおける部分断面模式図である。図8および図9に示すように、実施形態に係る軸受用軸1または軸受10を適用した遊星歯車減速機は、入力軸11と、当該入力軸11と同軸状に取り付けられた太陽歯車12と、太陽歯車12の外径側において減速機のケーシング(図示しない)に同心状態に固定された内歯歯車13と、太陽歯車12と内歯歯車13との間に介在し周方向に等間隔に(図示の場合は入力軸11から見て約90°ずつ周方向にずれた4個所に)配置された複数個の遊星歯車14と、各遊星歯車14の回転を支持する遊星ピンとしての軸受用軸1と、すべての軸受用軸1を回転自在な状態に連結した環状のキャリヤ16と、キャリヤ16と同心状態であって一体に設けられた出力軸17とにより構成される。
Claims (12)
- 転動体が接触する軌道面を含む外周面を備える軸受用軸であって、
炭素を0.7%以上含有する鋼により構成され、
前記軌道面には、窒素富化層が形成され、
前記窒素富化層の表面における圧縮残留応力の絶対値が600MPa以上1700MPa以下である、軸受用軸。 - 前記窒素富化層の表面における硬度はHv850以上Hv1000以下である、請求項1に記載の軸受用軸。
- 前記窒素富化層の表面粗さは算術平均粗さRaで0.2μm以下である、請求項1または請求項2に記載の軸受用軸。
- 前記窒素富化層の表層部における残留オーステナイト量が9体積%以下である、請求項1~請求項3のいずれか1項に記載の軸受用軸。
- 前記鋼は高炭素クロム軸受鋼である、請求項1~請求項4のいずれか1項に記載の軸受用軸。
- 軌道面を有する外周面を含む軸受用軸と、
前記軌道面に接触する表面を含む転動体とを備え、
前記軸受用軸は、炭素を0.7%以上含有する鋼により構成され、
前記軌道面には、窒素富化層が形成され、
前記窒素富化層の表面における圧縮残留応力の絶対値が600MPa以上1700MPa以下であり、
前記転動体の前記表面における表層部での残留オーステナイト量は、前記軸受用軸の前記軌道面に形成された前記窒素富化層の表層部における残留オーステナイト量より多い、軸受。 - 前記転動体の前記表面には窒素富化層が形成されている、請求項6に記載の軸受。
- 前記転動体は、クラウニング付ころである、請求項6または請求項7に記載の軸受。
- 前記軸受用軸の前記軌道面に形成された前記窒素富化層の表面における硬度はHv850以上Hv1000以下である、請求項6~請求項8のいずれか1項に記載の軸受。
- 前記軸受用軸の前記軌道面に形成された前記窒素富化層の表面粗さは算術平均粗さRaで0.2μm以下である、請求項6~請求項9のいずれか1項に記載の軸受。
- 前記軸受用軸の前記軌道面に形成された前記窒素富化層の表層部における残留オーステナイト量が9体積%以下である、請求項6~請求項10のいずれか1項に記載の軸受。
- 前記鋼は高炭素クロム軸受鋼である、請求項6~請求項11のいずれか1項に記載の軸受。
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CN201680071790.XA CN108368869B (zh) | 2015-12-09 | 2016-12-06 | 轴承用轴和轴承 |
DE112016005662.1T DE112016005662T5 (de) | 2015-12-09 | 2016-12-06 | Lagerwelle und Lager |
US16/060,388 US10458461B2 (en) | 2015-12-09 | 2016-12-06 | Bearing shaft and bearing |
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JP2015240277A JP6637304B2 (ja) | 2015-12-09 | 2015-12-09 | 軸受 |
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JP2015240278A JP2017106535A (ja) | 2015-12-09 | 2015-12-09 | 軸受 |
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JP2020008114A (ja) * | 2018-07-10 | 2020-01-16 | 株式会社ジェイテクト | 回転体支持用軸、回転体支持用軸の製造方法、及びころ軸受 |
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JP2005314794A (ja) * | 2004-03-30 | 2005-11-10 | Nsk Ltd | 転がり軸受 |
JP2006071022A (ja) * | 2004-09-02 | 2006-03-16 | Nsk Ltd | 転がり軸受 |
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EP1548145B1 (en) | 2002-10-17 | 2006-05-03 | NTN Corporation | Roller cam follower for an engine |
JP4576842B2 (ja) * | 2004-01-20 | 2010-11-10 | 日本精工株式会社 | 転がり軸受及びこれを用いたベルト式無段変速機 |
JP2015007265A (ja) * | 2013-06-25 | 2015-01-15 | 日本精工株式会社 | 転動軸 |
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JP2009019639A (ja) * | 2003-02-28 | 2009-01-29 | Ntn Corp | エンジンのローラ付きカムフォロアの製造方法 |
JP2005282854A (ja) * | 2004-03-03 | 2005-10-13 | Nsk Ltd | 転がり軸受 |
JP2005314794A (ja) * | 2004-03-30 | 2005-11-10 | Nsk Ltd | 転がり軸受 |
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