WO2021100746A1 - Élément de chemin de roulement, palier à roulement, bague de palier pour palier à roulement, et procédé de fabrication de bague de palier pour palier à roulement - Google Patents

Élément de chemin de roulement, palier à roulement, bague de palier pour palier à roulement, et procédé de fabrication de bague de palier pour palier à roulement Download PDF

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Publication number
WO2021100746A1
WO2021100746A1 PCT/JP2020/042944 JP2020042944W WO2021100746A1 WO 2021100746 A1 WO2021100746 A1 WO 2021100746A1 JP 2020042944 W JP2020042944 W JP 2020042944W WO 2021100746 A1 WO2021100746 A1 WO 2021100746A1
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WIPO (PCT)
Prior art keywords
peripheral surface
raceway
amount
retained austenite
inner ring
Prior art date
Application number
PCT/JP2020/042944
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English (en)
Japanese (ja)
Inventor
山田　昌弘
直輝 藤村
大木　力
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Ntn株式会社
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Publication date
Priority claimed from JP2019211179A external-priority patent/JP2021081047A/ja
Priority claimed from JP2020000362A external-priority patent/JP2021110341A/ja
Application filed by Ntn株式会社 filed Critical Ntn株式会社
Publication of WO2021100746A1 publication Critical patent/WO2021100746A1/fr

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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
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/34—Methods of heating
    • C21D1/42—Induction heating
    • 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
    • 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
    • F16C19/00—Bearings with rolling contact, for exclusively rotary movement
    • F16C19/22—Bearings with rolling contact, for exclusively rotary movement with bearing rollers essentially of the same size in one or more circular rows, e.g. needle bearings
    • F16C19/34—Bearings with rolling contact, for exclusively rotary movement with bearing rollers essentially of the same size in one or more circular rows, e.g. needle bearings for both radial and axial load
    • F16C19/36—Bearings with rolling contact, for exclusively rotary movement with bearing rollers essentially of the same size in one or more circular rows, e.g. needle bearings for both radial and axial load with a single row of rollers
    • 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
    • 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
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/25—Process efficiency

Definitions

  • the present invention relates to a method for manufacturing a raceway member, a rolling bearing, a raceway ring of a rolling bearing, and a raceway ring of a rolling bearing.
  • the conventional track member is manufactured by performing a heat treatment including quenching treatment and tempering treatment.
  • the tempering treatment is carried out by accommodating the entire molded product, which is the object to be treated, in the atmosphere furnace.
  • the dimensional change rate of the track member used in a high temperature environment is preferably kept low from the viewpoint of bearing life. For example, if the dimensional change rate of the inner diameter surface of the inner ring is suppressed to a low level, it is possible to suppress loosening of the fit between the inner diameter surface of the inner ring and the shaft to cause creep, and it is possible to suppress damage to the bearing.
  • Japanese Unexamined Patent Publication No. 2017-227334 discloses a technique for tempering a steel material at a temperature of 180 ° C. or higher and 230 ° C. or lower in order to reduce the average residual austenite amount of the entire track member to 18% by volume or less.
  • the track member manufactured by performing the above-mentioned tempering treatment for example, the track member manufactured without performing the tempering treatment under the above-mentioned conditions because it is not planned to be used in a high temperature environment.
  • the amount of martensite in the raceway surface and the circumferential surface (hereinafter referred to as the anti-tracking surface) located on the opposite side of the raceway surface, that is, the inner diameter surface of the inner ring or the outer diameter surface of the outer ring is suppressed to be low.
  • the hardness of the track surface and the anti-track surface is low.
  • the amount of retained austenite is smaller than that of the latter track member, but since it is necessary to reduce the amount of decrease in hardness of the raceway surface, the amount of decomposition of retained austenite is small. Therefore, the effect of suppressing the dimensional change rate is not sufficient, and the hardness of the raceway surface and the anti-trackway surface is reduced.
  • a main object of the present invention is to provide a raceway member and a rolling bearing in which the dimensional change rate of the anti-track surface is suppressed to a low level and the decrease in hardness of the raceway surface and the anti-track surface is suppressed.
  • the track member according to the present invention has a track surface extending along the circumferential direction and an anti-track surface facing the opposite side to the track surface.
  • the amount of retained austenite on the orbital plane is larger than the amount of retained austenite on the anti-orbital plane.
  • the difference between the amount of retained austenite on the orbital plane and the amount of retained austenite on the anti-orbital plane is 3% by volume or more.
  • the average residual austenite amount as a whole is 20% by volume or less. In the track member, the average residual austenite amount as a whole is 10% by volume or less.
  • the amount of retained austenite on the anti-track surface is 5% by volume or less.
  • the hardness of the anti-track surface is 600 Hv or more.
  • the rolling bearing according to the present invention includes an inner ring having an inner ring raceway surface and an inner diameter surface located on the side opposite to the inner ring raceway surface, an outer ring having an outer ring raceway surface facing the inner ring raceway surface, and an inner ring raceway surface and an outer ring. It includes a plurality of rolling elements that come into contact with the raceway surface.
  • the inner ring is the track member.
  • the inner ring raceway surface is the raceway surface of the raceway member.
  • the inner diameter surface is the anti-track surface of the track member.
  • the present invention it is possible to provide a raceway member and a rolling bearing in which the dimensional change rate of the circumferential surface is suppressed to a low level and the decrease in hardness of the raceway surface and the anti-track surface is suppressed.
  • the rolling bearing according to the present embodiment is, for example, a radial ball bearing, and more specifically, a deep groove ball bearing 1 shown in FIG.
  • the deep groove ball bearing 1 is a rolling element arranged between the annular outer ring 11, the annular inner ring 12 arranged inside the outer ring 11, and the outer ring 11 and the inner ring 12, and held by the annular cage 14. It is provided with a plurality of balls 13 which are.
  • the central axis of the outer ring 11 is arranged so as to overlap the central axis of the inner ring 12.
  • the outer ring 11 has an inner peripheral surface 11B and an outer peripheral surface 11C as an outer diameter surface.
  • An outer ring raceway surface 11A extending along the circumferential direction is formed on the inner peripheral surface 11B of the outer ring 11.
  • the inner ring 12 has an outer peripheral surface 12B facing the outer peripheral side in the radial direction and an inner peripheral surface 12C as an inner diameter surface.
  • An inner ring raceway surface 12A extending along the circumferential direction is formed on the outer peripheral surface 12B of the inner ring 12.
  • the inner ring 12 is arranged inside the outer ring 11 so that the inner ring raceway surface 12A faces the outer ring raceway surface 11A.
  • the plurality of balls 13 are in contact with the outer ring raceway surface 11A and the inner ring raceway surface 12A on the rolling surface 13A, and are arranged at a predetermined pitch in the circumferential direction by the cage 14. As a result, the plurality of balls 13 are rotatably held on the annular orbits of the outer ring 11 and the inner ring 12. With such a configuration, the outer ring 11 and the inner ring 12 of the deep groove ball bearing 1 can rotate relative to each other.
  • the inner ring 12 is a track member according to the present embodiment.
  • the inner ring 12 has an inner ring raceway surface 12A extending along the circumferential direction and an inner peripheral surface 12C as a circumferential surface extending along the circumferential direction and extending along the axial direction.
  • the amount of retained austenite on the inner ring raceway surface 12A is larger than the amount of retained austenite on the inner peripheral surface 12C.
  • the amount of retained austenite in the inner ring 12 tends to gradually decrease from the inner ring raceway surface 12A to the inner peripheral surface 12C in the radial direction.
  • the difference between the amount of retained austenite on the inner ring raceway surface 12A and the amount of retained austenite on the inner peripheral surface 12C is 3% by volume or more.
  • the difference between the amount of retained austenite on the inner ring raceway surface 12A and the amount of retained austenite on the inner peripheral surface 12C is, for example, 10% by volume or less, for example, less than 5% by volume.
  • the above difference between the amount of retained austenite on the inner ring raceway surface 12A and the amount of retained austenite on the inner peripheral surface 12C exceeds the difference between the amount of retained austenite on the raceway surface and the amount of retained austenite on the inner peripheral surface realized by the conventional tempering treatment. This is realized by the tempering process according to the present embodiment, which will be described later.
  • the amount of retained austenite is calculated from the diffraction intensities of the martensite phase and the austenite phase measured by X-ray diffraction.
  • the amount of retained austenite on the inner peripheral surface 12C is, for example, 5% by volume or less, preferably less than 5% by volume.
  • the amount of retained austenite on the inner ring raceway surface 12A is, for example, 10% by volume or more, preferably 15% by volume or more.
  • the above difference between the amount of retained austenite on the inner ring raceway surface 12A and the amount of retained austenite on the inner peripheral surface 12C exceeds the difference between the amount of retained austenite on the raceway surface and the amount of retained austenite on the inner peripheral surface realized by the conventional tempering treatment. This is realized by the tempering process in the method for manufacturing the inner ring 12 according to the present embodiment, which will be described later.
  • the average residual austenite amount of the entire inner ring 12 that is, the average value calculated from the distribution of the residual austenite amount in the radial direction from the inner ring raceway surface 12A to the inner peripheral surface 12C of the inner ring 12 is 20% by volume or less.
  • the average residual austenite amount of the inner ring 12 as a whole is 20% by volume or less regardless of whether or not the carburizing and nitriding treatment is performed in the method for producing the inner ring 12.
  • the average residual austenite amount of the entire inner ring 12 can be 10% by volume or less.
  • the hardness of the inner ring raceway surface 12A exceeds the hardness of the inner peripheral surface 12C.
  • the hardness of the inner ring raceway surface 12A is, for example, 650 Hv or more, preferably 700 Hv or more.
  • the hardness of the inner peripheral surface 12C is, for example, 600 Hv or more and 700 Hv or less.
  • the hardness of the inner ring raceway surface 12A is, for example, 750 Hv or more.
  • the hardness of each surface is measured according to the Vickers hardness test method specified in the JIS standard (JJS Z 2244: 2009).
  • the rolling bearing according to the present embodiment may be, for example, a radial roller bearing, and more specifically, a conical roller bearing 2 shown in FIG.
  • the conical roller bearing 2 includes an annular outer ring 21 and an inner ring 22, a plurality of rollers 23 which are rolling elements, and an annular cage 24.
  • An outer ring raceway surface 21A extending along the circumferential direction is formed on the inner peripheral surface of the outer ring 21, and an inner ring raceway surface 22A extending along the circumferential direction is formed on the outer peripheral surface of the inner ring 22.
  • the inner ring 22 is arranged inside the outer ring 21 so that the inner ring raceway surface 22A faces the outer ring raceway surface 21A.
  • the plurality of rollers 23 are in contact with the outer ring raceway surface 21A and the inner ring raceway surface 22A on the rolling surface 23A, and are arranged at a predetermined pitch in the circumferential direction by the cage 24. As a result, the roller 23 is rotatably held on the annular orbit of the outer ring 21 and the inner ring 22. Further, in the conical roller bearing 2, the apex of each of the cone including the outer ring raceway surface 21A, the cone including the inner ring raceway surface 22A, and the cone including the locus of the rotation axis when the roller 23 rolls is on the center line of the bearing. It is configured to intersect at one point.
  • the inner ring 22 is a track member according to the present embodiment, like the inner ring 12.
  • the inner ring 22 has the same configuration as the inner ring 12.
  • the inner ring 22 has an inner ring raceway surface 22A extending along the circumferential direction and an inner peripheral surface 22C as a circumferential surface extending along the circumferential direction and extending along the axial direction.
  • the amount of retained austenite on the inner ring raceway surface 22A is larger than the amount of retained austenite on the inner peripheral surface 22C.
  • the amount of retained austenite in the inner ring 22 tends to gradually decrease from the inner ring raceway surface 22A to the inner peripheral surface 22C in the radial direction.
  • the amount of retained austenite on the inner peripheral surface 22C is, for example, 5% by volume or less, preferably less than 5% by volume.
  • the amount of retained austenite on the inner ring raceway surface 22A is, for example, 10% by volume or more, preferably 15% by volume or more.
  • the above difference between the amount of retained austenite on the inner ring raceway surface 22A and the amount of retained austenite on the inner peripheral surface 22C exceeds the difference between the amount of retained austenite on the raceway surface and the amount of retained austenite on the inner peripheral surface realized by the conventional tempering treatment. This is realized by the tempering process in the method for manufacturing the inner ring 22 according to the present embodiment described later.
  • the average residual austenite amount of the inner ring 22 as a whole that is, the average value calculated from the distribution of the residual austenite amount in the radial direction from the inner ring raceway surface 22A to the inner peripheral surface 22C of the inner ring 22 is 20% by volume or less.
  • the average residual austenite amount of the inner ring 22 as a whole is 20% by volume or less regardless of whether or not the carburizing and nitriding treatment is performed in the method for producing the inner ring 22.
  • the average residual austenite amount of the entire inner ring 22 can be 10% by volume or less.
  • the above difference between the amount of retained austenite on the inner ring raceway surface 22A and the amount of retained austenite on the inner peripheral surface 22C exceeds the difference between the amount of retained austenite on the raceway surface and the amount of retained austenite on the inner peripheral surface realized by the conventional tempering treatment. This is realized by the tempering process according to the present embodiment, which will be described later.
  • the hardness of the inner ring raceway surface 22A exceeds the hardness of the inner peripheral surface 22C.
  • the hardness of the inner ring raceway surface 22A is, for example, 650 Hv or more, preferably 700 Hv or more.
  • the hardness of the inner peripheral surface 22C is, for example, 600 Hv or more and 700 Hv or less.
  • the hardness of the inner ring raceway surface 22A is, for example, 750 Hv or more.
  • the rolling bearing according to the present embodiment is manufactured by the method for manufacturing the rolling bearing according to the present embodiment shown in FIG.
  • the rolling bearing manufacturing method according to the present embodiment includes a step (S10) of preparing a molded body to be inner rings 12 and 22 (track members) and quenching of the molded body.
  • S40 and.
  • Inner rings 12 and 22 are manufactured by the above steps (S10) to (S40).
  • the method for manufacturing a rolling bearing according to the present embodiment is a step of preparing outer rings 11 and 21 and balls 13 or rollers 23 and assembling inner rings 12, 22, outer rings 11 and 21 and balls 13 or rollers 23. (S50) is further provided.
  • a steel material made of steel is prepared.
  • the steel material is prepared as, for example, steel bar or steel wire.
  • the steel material is subjected to processing such as cutting, forging, and turning.
  • a steel material (molded body) formed into the approximate shape of the inner rings 12 and 22 is produced.
  • the molded body has a first peripheral surface 10C facing inward in the radial direction and a second peripheral surface facing outward in the radial direction.
  • the inner peripheral surfaces 12C and 22C of the inner rings 12 and 22 are formed by grinding the first peripheral surface 10C in the subsequent step (S40).
  • the inner ring raceway surfaces 12A and 22A of the inner rings 12 and 22 are formed by grinding the second peripheral surface in the post-process (S40).
  • a quench hardening treatment is performed on the molded product prepared in the previous step (S10).
  • a carburizing and nitriding treatment for carburizing and nitriding the molded product is carried out.
  • a nitrogen diffusion treatment for diffusing the nitrogen that has infiltrated into the molded body by the carburizing and nitrification treatment is carried out.
  • the whole of the molded body is heated to a temperature T 1 of the above point A, retention time t 1 (soaking time) for soaking only be retained.
  • the molded product is cooled to a temperature T 2 below the Ms point (martensite transformation point).
  • This cooling treatment is carried out by immersing the target material in a coolant such as oil or water. As a result, the target material is quenched.
  • the quenching treatment is carried out under conditions such that the hardness of the hardened target material exceeds the hardness of the tempered target material described later.
  • the difference between the amount of retained austenite on the second peripheral surface and the amount of retained austenite on the first peripheral surface 10C of the molded product subjected to the quench hardening treatment is less than 3% by volume.
  • the amount of retained austenite on each of the first peripheral surface and the second peripheral surface of the molded product subjected to the quench hardening treatment (hereinafter referred to as the initial retained austenite amount) is not particularly limited. For example, it is 5% by volume or more and 13% by volume or less.
  • the tempering treatment is performed on the molded product that has been quench-hardened in the previous step (S20).
  • the first tempering treatment as a conventional dimensional stabilization treatment in which the entire molded product is heated, and the first peripheral surface 10C while the second peripheral surface of the molded product is locally cooled.
  • a second tempering process is performed in which the heat is locally heated. Local cooling of the second peripheral surface is continuously performed in the second tempering process from the start of heating to the end of heating of the first peripheral surface 10C.
  • the surface temperature of the first peripheral surface 10C of the molded product is maintained until the holding time t 2 (tempering time) elapses at the tempering temperature T 3.
  • the holding time t 2 is the time from when the first peripheral surface 10C tempering temperature T 3 is reached in the second tempering treatment to the end of heating.
  • Surface temperature of the second circumferential surface of the green body after being held by the first temperature reached T 4 lower than the tempering temperature T 3, first reaches a temperature T 4 or more tempering temperature T 3 below the second temperature reached It is held at T 5 until the holding time t 3 elapses.
  • the holding time t 3 is the time from when the second peripheral surface reaches the second reaching temperature T 5 in the second tempering process until the heating of the second peripheral surface is completed.
  • the second reached temperature T 5 is, for example, equal to the tempering temperature T 3.
  • the tempering temperature T 3 and the holding time t 2 are values in which the amount of retained austenite on the inner peripheral surfaces 12C and 22C is predetermined from the viewpoint of achieving the dimensional stability and hardness required for the inner peripheral surfaces 12C and 22C. It is set so that the hardness of the inner peripheral surfaces 12C and 22C is equal to or greater than a predetermined value.
  • the first ultimate temperature T 4 , the second ultimate temperature T 5 , and the holding time t 3 of the second peripheral surface are required for the hardness required for the inner ring raceway surfaces 12A and 22A and for the entire inner rings 12 and 22.
  • the hardness of the inner ring raceway surfaces 12A and 22A should be equal to or higher than the predetermined value, and the residual austenite amount of the inner ring raceway surfaces 12A and 22A should be equal to or lower than the predetermined value. Is set to.
  • the first tempering treatment and the second tempering treatment are carried out by, for example, the heating method and the cooling method shown in FIGS. 4 and 5.
  • the heating of the first peripheral surface 10C is carried out by, for example, induction heating using the first coil 30, preferably high frequency induction heating.
  • the first coil 30 is arranged in the molded body 10 so as to face only the first peripheral surface 10C.
  • An alternating current of 3 kHz or higher is supplied to the first coil 30.
  • a high-frequency alternating current is supplied to the first coil 30
  • the temperature rises on the second peripheral surface 10A side in the radial direction as compared with the induction heating in which a lower-frequency alternating current is supplied to the first coil 30. Is suppressed, so that the difference between the tempering temperature T 3 and the first reached temperature T 4 becomes large.
  • the cooling of the second peripheral surface 10A is carried out by supplying a cooling solvent such as water to the second peripheral surface 10A of the molded body 10 by using, for example, the injection unit 31.
  • the cooling is carried out so as not to cool the first peripheral surface 10C.
  • the cooling is carried out so that the water supplied to the second peripheral surface 10A is not supplied to the first peripheral surface 10C.
  • the injection unit 31 is arranged so as to face the second peripheral surface 10A of the molded body 10 in the second tempering process, and injects water onto the second peripheral surface 10A.
  • the first coil 30 and the injection unit 31 are arranged so as to sandwich the molded body 10 in the radial direction of the molded body 10, for example.
  • the cooling may be performed on a region of the second peripheral surface 10A that is ground to form the inner ring raceway surfaces 12A and 22A at least in the subsequent step (S40).
  • the first tempering process and the second tempering process are carried out, for example, by relatively rotating the molded body 10, the first coil 30, and the injection unit 31 in the circumferential direction.
  • the relative positions of the first coil 30 and the injection unit 31 are fixed throughout, for example, the second tempering process.
  • the first tempering process is carried out by putting the entire molded product into a heat treatment furnace heated to a temperature of 180 ° C. or higher and 230 ° C. or lower.
  • the first coil 30 heats the first peripheral surface 10C and the injection unit 31 cools the second peripheral surface 10A.
  • the set values of the tempering temperature T 3 , the holding time t 2 , the first reaching temperature T 4 , the second reaching temperature T 5, and the holding time t 3 are based on, for example, the following formulas 1, 2, and 3. Is set.
  • the coefficients of the above formulas 1, 2 and 3 vary depending on the composition of the steel of the molded product, the amount of the initial retained austenite and the like.
  • the above formula 1 is a prediction formula for predicting the relationship between the tempering temperature T 3 (unit: ° C.) and the above first reached temperature T 4 (unit: ° C.).
  • the present inventors consider a molded product in which the heating is carried out by induction heating on the first peripheral surface 10C and the cooling is carried out by jetting water on the second peripheral surface 10A. The temperature distribution in the member to be heated was simulated and analyzed.
  • the above formula 1 was obtained by the present inventors from the results of the above simulation analysis. As a result of the analysis, it was confirmed that the first reached temperature T 4 changes linearly with respect to the tempering temperature T 3 (see FIG. 8). The details of the simulation analysis will be described later.
  • the above formula 1 is changed to the prediction formula in the different method.
  • the above formula 2 is based on the reached temperature T (unit: K), holding time t (unit: seconds) during tempering treatment, and residual austenite amount ⁇ (remaining austenite amount ⁇ ) on the first peripheral surface 10C or the second peripheral surface 10A after tempering treatment. It is a prediction formula that predicts the relationship of unit: volume%).
  • the residual austenite amount ⁇ of the first peripheral surface 10C after the second tempering treatment is obtained by substituting the tempering temperature T 3 for the ultimate temperature T in Equation 2 and substituting the holding time t 2 for the holding time t. Calculated.
  • the residual austenite amount ⁇ of the second peripheral surface 10A after the second tempering treatment is obtained by substituting the second reaching temperature T 5 for the reaching temperature T in Equation 2 and substituting the holding time t 3 for the holding time t. It is estimated that the value is less than the calculated value by the amount of decomposition in the first tempering process.
  • the above formula 2 is based on Non-Patent Document 1 (Takeshi Inoue, "Application of new tempering parameters and their application to the method of integrating the tempering effect along the continuous temperature rise curve", Iron and Steel, 66, 10 (1980) 1533.). It was experimentally obtained by the present inventors based on the relational expression between the hardness and the tempering temperature described in 1.
  • the above formula 3 is based on the reached temperature T (unit: K), holding time t (unit: seconds) during the tempering process, and hardness M (unit: unit) of the first peripheral surface 10C or the second peripheral surface 10A after the tempering process.
  • HV is a prediction formula that predicts the relationship.
  • the hardness M of the first peripheral surface 10C after the tempering process is calculated by substituting the tempering temperature T 3 for the ultimate temperature T in Equation 3 and substituting the holding time t 3 for the holding time t.
  • the hardness M of the second peripheral surface 10A after the tempering treatment is estimated to be about a value calculated by substituting the second ultimate temperature T 5 for the ultimate temperature T in Equation 3.
  • the above formula 3 was experimentally obtained by the present inventors based on the relational expression between the amount of retained austenite and the tempering temperature described in JP-A-10-102137.
  • the tempering temperature T 3 and the holding time t 2 are such that the amount of retained austenite on the first peripheral surface 10C is equal to or less than the predetermined value and the hardness of the first peripheral surface 10C is based on the mathematical formulas 2 and 3. Is set so as to be equal to or greater than the above-mentioned predetermined value.
  • the first ultimate temperature T 4 , the second ultimate temperature T 5, and the holding time t 3 are such that the hardness of the second peripheral surface 10A is equal to or higher than the predetermined value based on the above equations 1, 2, and 3. Is set to be. Further, the second reaching temperature T 5 and the holding time t 3 are set so that the amount of retained austenite on the second peripheral surface 10A is equal to or less than the predetermined value.
  • the holding time t 2 and the holding time t 3 are set as follows, for example.
  • the lower limit of the holding time t 2 of the tempering temperature T 3 in the tempering process is set to realize the initial residual austenite amount and the dimensional stability required for the inner rings 12 and 22. It is calculated from the upper limit of the residual austenite amount of 10C based on the above formula 2.
  • the lower limit of the holding time t 3 in the second tempering process is set to realize the initial residual austenite amount and the dimensional stability required for the inner rings 12 and 22, and the retained austenite on the second peripheral surface 10A is set. It is calculated from the upper limit of the amount based on the above formula 2.
  • the upper limit of the holding time t 3 is, the hardness lower limit of the first peripheral 10C which is set to achieve the hardness required for the inner ring 12, 22, based on the equation 3 Calculated. Further, the upper limit value of the holding time t 3 is calculated based on the above formula 3 from the lower limit value of the hardness of the second peripheral surface 10A set to realize the hardness required for the inner rings 12 and 22. Will be done.
  • the initial residual austenite amount of the molded product is 5% by volume
  • the upper limit of the retained austenite amount of the first peripheral surface 10C is 0% by volume
  • the lower limit of the hardness of the first peripheral surface 10C is 670HV.
  • the lower limit of the hardness of the second peripheral surface 10A is 700 HV. From the above formula 2, the graph shown in FIG. 6 is calculated.
  • FIG. 6 shows the holding time t 2 (heating time) required to reduce the initial residual austenite amount by a predetermined amount when the tempering temperature T 3 is 350 ° C. in the tempering treatment according to the present embodiment. ) And the amount of initial retained austenite.
  • the holding time t 2 with respect to the first peripheral surface is 156 seconds or more. Is set. For example, of the holding time t 2 , the lower limit of the holding time in the first tempering process is set as 156 seconds.
  • the hardness of the second peripheral surface 10A is 700 HV or more and the hardness of the first peripheral surface 10C.
  • the holding time t 3 with respect to the second peripheral surface 10A is set to 12 seconds or less.
  • the holding time t 2 is set to 168 seconds, which is the sum of 156 seconds and 12 seconds.
  • the step (S40) at least the second peripheral surface 10A of the molded body 10 is ground.
  • the inner rings 12 and 22 having the inner ring raceway surfaces 12A and 22A are formed.
  • the inner peripheral surfaces 12C and 22C are the first peripheral surfaces that have been tempered.
  • the inner peripheral surfaces 12C and 22C are surfaces formed by grinding the first peripheral surface that has been tempered.
  • the outer rings 11 and 21 and the balls 13 or rollers 23 are prepared.
  • the inner ring 12 manufactured in the previous step (S40) the prepared outer ring 11 and the ball 13 are assembled.
  • the deep groove ball bearing 1 shown in FIG. 1 is manufactured.
  • the inner ring 22 manufactured in the previous step (S40) and the prepared outer ring 21 and roller 23 are assembled.
  • the conical roller bearing 2 shown in FIG. 2 is manufactured.
  • step (S20) carburizing and nitriding treatment is carried out, but the present invention is not limited to this.
  • the above step (S20) only the above quench hardening treatment may be carried out.
  • the amount of retained austenite in the molded product after the quenching treatment is generally smaller than that in the case where the carburizing treatment is carried out. That is, the difference between the amount of retained austenite on the inner ring raceway surfaces 12A and 22A and the amount of retained austenite on the inner peripheral surfaces 12C and 22C due to the above tempering treatment is the difference between the inner ring 12 and the inner ring 12 It is smaller than that of 22.
  • the difference becomes larger than that of the conventional inner ring in which the conventional tempering treatment is performed instead of the tempering treatment.
  • the above difference between the inner rings 12 and 22 manufactured without performing the carburizing and nitriding treatment can be, for example, 3% by volume or more and 5% by volume or less.
  • the outer rings 11 and 21 may also be configured as the track members according to the present embodiment.
  • the amount of retained austenite on the outer ring raceway surface 11A is larger than the amount of retained austenite on the outer peripheral surface 11C as the circumferential surface, and the difference between the two is 3% by volume or more.
  • the amount of retained austenite on the outer ring raceway surface 21A is larger than the amount of retained austenite on the outer peripheral surface 21C as the circumferential surface, and the difference between the two is 3% by volume or more.
  • the inner rings 12 and 22 as the raceway members according to the present embodiment are made of steel and extend along the circumferential direction with the inner ring raceway surfaces 12A and 22A, and extend along the circumferential direction and along the axial direction. It has inner peripheral surfaces 12C and 22C as an extending circumferential surface.
  • the amount of retained austenite on the inner ring raceway surfaces 12A and 22A is larger than the amount of retained austenite on the inner peripheral surfaces 12C and 22C.
  • the difference between the amount of retained austenite on the inner ring raceway surfaces 12A and 22A and the amount of retained austenite on the inner peripheral surfaces 12C and 22C is 3% by volume or more.
  • the entire molded body is heated in the atmosphere furnace, so that retained austenite and martensite in the region that should be the raceway surface are decomposed. Therefore, in the inner ring as the first comparative example manufactured by the conventional tempering treatment, the difference between the amount of retained austenite on the raceway surface and the amount of retained austenite on the inner diameter surface is less than 3% by volume. As a result, in the inner ring, the dimensional stability of the inner diameter surface and the hardness of the raceway surface showed a trade-off relationship, and it was difficult to increase both at the same time.
  • the second period in the tempering process is performed.
  • the reaching temperature of the surface becomes high, and the decomposition of retained austenite and martensite on the second peripheral surface side proceeds.
  • the difference between the amount of retained austenite on the raceway surface and the amount of retained austenite on the inner diameter surface is 3 volumes even in the inner ring as a second comparative example produced by the tempering treatment in which only the heating is performed and the cooling is not performed. It will be less than%.
  • the dimensional stability of the inner diameter surface and the hardness of the raceway surface show a trade-off relationship, and it is difficult to increase both at the same time.
  • the temperature of the second peripheral surface 10A is set to the temperature of the first peripheral surface 10C.
  • some of the time of the holding time t 2, which is held in the tempering temperature T 3 is held in the first ultimate temperature T 4 lower than the tempering temperature T 3.
  • the first ultimate temperature T 4 can be made lower than the ultimate temperature of each of the second peripheral surfaces of the first comparative example and the second comparative example by the above cooling. Therefore, in the tempering treatment according to the present embodiment, decomposition of retained austenite and martensite on the second peripheral surface 10A side is suppressed as compared with the first comparative example and the second comparative example.
  • the residual austenite amount of the inner ring raceway surfaces 12A and 22A formed based on the second peripheral surface is determined.
  • the amount of retained austenite on the inner peripheral surfaces 12C and 22C formed based on the first peripheral surface is 3% by volume or more larger than the amount of retained austenite.
  • the amount of retained austenite on the inner ring raceway surfaces 12A and 22A is larger than that of the inner rings of the first and second comparative examples, and the amount of retained austenite on the inner peripheral surfaces 12C and 22C is large. It can be reduced as compared with that of the inner ring of the first comparative example and the second comparative example.
  • the dimensional stability of the inner peripheral surfaces 12C and 22C and the hardness of the inner ring raceway surfaces 12A and 22A are simultaneously enhanced as compared with the inner rings of the first comparative example and the second comparative example. There is.
  • the amount of retained austenite on the inner peripheral surfaces 12C and 22C is the same as that of the inner rings of the first and second comparative examples, and the amount of retained austenite on the inner ring raceway surfaces 12A and 22A. Can be increased as compared with that of the inner ring of the first comparative example and the second comparative example.
  • the dimensional stability of the inner peripheral surfaces 12C and 22C is made equivalent to that of the inner rings of the first comparative example and the second comparative example, and the hardness of the inner ring raceway surfaces 12A and 22A is high. It is greatly improved as compared with that of the inner ring of the first comparative example and the second comparative example.
  • the amount of retained austenite on the inner ring raceway surfaces 12A and 22A is equal to that of the inner rings of the first and second comparative examples, and the amount of retained austenite on the inner peripheral surfaces 12C and 22C. Can be reduced as compared with that of the inner ring of the first comparative example and the second comparative example.
  • the hardness of the inner ring raceway surfaces 12A and 22A is the same as that of the inner rings of the first comparative example and the second comparative example, and the dimensional stability of the inner peripheral surfaces 12C and 22C is improved. It is greatly improved as compared with that of the inner ring of the first comparative example and the second comparative example.
  • the tempering temperature of the tempering treatment is equal to the tempering temperature T 3
  • the reaching temperature of the second peripheral surface is the first reaching temperature.
  • the second tempering treatment is performed after the first tempering treatment.
  • the entire molded body is heated. Therefore, the amount of retained austenite on the inner ring raceway surfaces 12A and 22A formed based on the second peripheral surface 10A is smaller than the amount of retained austenite on the inner ring raceway surface of the third comparative example.
  • the average residual austenite amount of the inner rings 12 and 22 as a whole is also smaller than that of the third comparative example, and the overall dimensional stability of the inner rings 12 and 22 is improved as compared with that of the third comparative example.
  • the inner rings 12 and 22 are manufactured after undergoing carburizing and nitriding treatment.
  • the average residual austenite amount of the inner rings 12 and 22 is, for example, 5% by volume or more and 25% by volume or less.
  • the dimensional stability of the inner peripheral surfaces 12C and 22C and the hardness of the inner ring raceway surfaces 12A and 22A are simultaneously and greatly improved as compared with the first comparative example and the second comparative example. There is. Further, the overall dimensional stability of the inner rings 12 and 22 is higher than that of the third comparative example.
  • the inner rings 12 and 22 may be manufactured without undergoing carburizing and nitrification treatment.
  • the total average retained austenite amount of the inner rings 12 and 22 can be 10% by volume or less. Therefore, in such inner rings 12 and 22, the dimensional stability of the inner peripheral surfaces 12C and 22C and the hardness of the inner ring raceway surfaces 12A and 22A are at the same time as compared with the inner rings of the first comparative example and the second comparative example. It has improved significantly.
  • the hardness of the inner ring raceway surfaces 12A and 22A of the inner rings 12 and 22 is 700 Hv or more.
  • the tempering treatment according to the present embodiment can suppress the decomposition of martensite on the second peripheral surface of the molded product as compared with the conventional tempering treatment. Therefore, the hardness of the inner ring raceway surfaces 12A and 22A may exceed the hardness of the raceway surfaces of the inner rings of the first comparative example and the second comparative example.
  • the inner rings 12 and 22 are the inner rings of the deep groove ball bearing 1 or the conical roller bearing 2 which are radial bearings, and the inner peripheral surfaces 12C and 22C are surfaces located on the opposite sides of the inner ring raceway surfaces 12A and 22A in the radial direction. is there.
  • the deep groove ball bearing 1 provided with the inner ring 12 has higher dimensional stability of the inner peripheral surface 12C and hardness of the inner ring raceway surface 12A at the same time than the deep groove ball bearings provided with the inner rings of the first comparative example and the second comparative example. Because it is a bearing, it has a long life.
  • the conical roller bearing 2 provided with the inner ring 22 has the dimensional stability of the inner peripheral surface 22C and the hardness of the inner ring raceway surface 22A at the same time as compared with the conical roller bearings having the inner rings of the first comparative example and the second comparative example. Because it is enhanced, it has a long life.
  • the details of the above simulation analysis regarding the second tempering process according to the present embodiment will be described below.
  • the simulation analysis was performed by heat conduction analysis by the finite element method.
  • the member to be heated simulating the molded body was made of JIS standard SUJ2 and was a ring having a thickness of 3 mm in the axial direction. Further, it was assumed that the member to be heated was subjected to the above quenching treatment.
  • the tempering process of the member to be heated was simulated using the analysis model shown in FIG. 7, and the temperature distribution inside the member to be heated at that time was analyzed. In this analysis model, tempering conditions were set in which the heating of the first peripheral surface of the molded product was induced and the cooling of the second peripheral surface was water cooling.
  • FIG. 8 shows the heating temperature and the ultimate temperature of the cooled second peripheral surface when the heating temperature for the first peripheral surface is 180 ° C. or higher and 490 ° C. or lower and the holding time is 1 minute. It is a graph which shows the relationship.
  • the horizontal axis of FIG. 8 indicates the heating temperature (unit: ° C.) with respect to the first peripheral surface, and the vertical axis of FIG. 8 indicates the ultimate temperature (unit: ° C.) of the second peripheral surface.
  • the temperature reached by the second peripheral surface changed linearly with respect to the heating temperature with respect to the first peripheral surface.
  • the above formula 1 was derived from the graph of FIG. From FIG.
  • the temperature difference between the first peripheral surface and the second peripheral surface can be sufficiently increased, and the residual austenite amount and the inner peripheral surface of the inner ring raceway surface can be sufficiently increased. It was confirmed that the difference from the amount of retained austenite in the above can be 3% by volume or more.
  • FIG. 9 is a graph showing the temperature changes of the first peripheral surface and the second peripheral surface with respect to the elapsed time from the start of heating with the heating temperature of the first peripheral surface to 420 ° C. and the above-mentioned cooling.
  • the horizontal axis of FIG. 9 indicates the elapsed time (unit: seconds) from the start of heating, and the vertical axis of FIG. 9 indicates the temperatures (unit: ° C.) of the first peripheral surface and the second peripheral surface.
  • the temperature of the first peripheral surface reached 390 ° C., which is 90% of the tempering temperature.
  • the temperature of the second peripheral surface reached 220 ° C., which is 90% of the temperature estimated from the above equation 1, about 5 seconds after the start of heating. Further, after the temperature of the second peripheral surface reached the above-estimated temperature, the temperature rise of the second peripheral surface was suppressed even though the heating of the first peripheral surface was continued. That is, it was confirmed that the temperature rise of the second peripheral surface was sufficiently suppressed by the above water cooling.
  • FIG. 10 is a diagram showing the temperature distribution inside the member to be heated when 30 seconds have passed since the start of heating and cooling at a heating temperature of 350 ° C. for the first peripheral surface.
  • the temperature inside the member to be heated gradually decreases from the first peripheral surface to the second peripheral surface, and the amount of decrease from the temperature of the first peripheral surface is the first circumference. It was confirmed that it changed linearly with respect to the distance from the surface. Further, it was confirmed that the temperature reached in the region where the raceway surface is formed can be suppressed to a temperature at which the decomposition of martensite can be sufficiently suppressed, even when the grinding allowance in the above step (S50) is taken into consideration.
  • the heating and cooling shown in FIG. 10 were carried out on the member to be heated having a residual austenite amount of 14.4% by volume and a hardness of 780Hv on the first peripheral surface and the second peripheral surface before the tempering treatment.
  • the amount of retained austenite on the first peripheral surface is 2% by volume or less and the hardness of the first peripheral surface is 680Hv
  • the amount of retained austenite on the second peripheral surface is 14.1% by volume and the hardness is 779Hv. Met.
  • the conventional tempering treatment is carried out on a member to be heated in which the amount of retained austenite on the first and second peripheral surfaces before the tempering treatment is 14.4% by volume and the hardness is 780 Hv
  • the first The difference between the amount of retained austenite on the peripheral surface and the amount of retained austenite on the second peripheral surface was less than 5% by volume.
  • the method for manufacturing the raceway member according to the present embodiment it is possible to manufacture an inner ring in which the amount of retained austenite on the raceway surface is 5% by volume or more larger than the amount of retained austenite on the first peripheral surface. .. Further, according to the method for manufacturing a track member according to the present embodiment, the amount of residual austenite on the first peripheral surface is lower and the residual austenite on the second peripheral surface is lower than that in the conventional method for manufacturing a track member including tempering treatment. It was confirmed that an inner ring with a high amount of austenite could be produced.
  • the raceway ring of the rolling bearing according to the embodiment is, for example, an inner ring of a deep groove ball bearing (hereinafter, referred to as "inner ring 110").
  • inner ring 110 an inner ring of a deep groove ball bearing
  • the raceway ring of the rolling bearing according to the embodiment is not limited to this.
  • the raceway ring of the rolling bearing according to the embodiment may be an outer ring of a deep groove ball bearing, or may be a raceway ring of a rolling bearing other than the deep groove ball bearing.
  • the inner ring 110 is made of hardened steel. That is, this steel contains martensite crystal grains and retained austenite crystal grains. This steel may contain other than martensite crystal grains and retained austenite crystal grains (for example, ferrite crystal grains and carbide grains). This steel is, for example, SUJ2, which is a high carbon chrome bearing steel defined in the JIS standard (JIS G 4805: 2008).
  • FIG. 11 is a plan view of the inner ring 110.
  • FIG. 12 is a cross-sectional view taken along the line XII-XII of FIG. As shown in FIGS. 11 and 12, the inner ring 110 has an annular shape. The inner ring 110 has a central axis A.
  • the inner ring 110 has a first end surface 110a and a second end surface 110b, an inner peripheral surface 110c, and an outer peripheral surface 110d.
  • the first end surface 110a, the second end surface 110b, the inner peripheral surface 110c, and the outer peripheral surface 110d may be collectively referred to as the surface of the inner ring 110.
  • the first end face 110a and the second end face 110b form end faces in a direction along the central axis A (hereinafter, referred to as "axial direction").
  • the second end surface 110b is the opposite surface of the first end surface 110a in the axial direction.
  • the inner peripheral surface 110c extends in a direction along the circumference centered on the central axis A (hereinafter, referred to as "circumferential direction").
  • the inner peripheral surface 110c faces the central axis A side.
  • the inner peripheral surface 110c is connected to the first end surface 110a and the second end surface 110b.
  • the inner ring 110 is fitted to a shaft (not shown) on the inner peripheral surface 110c.
  • the outer peripheral surface 110d extends in the circumferential direction.
  • the outer peripheral surface 110d faces the side opposite to the central axis A. That is, the outer peripheral surface 110d is the opposite surface of the inner peripheral surface 110c in the direction orthogonal to the central axis A and passing through the central axis A (hereinafter, referred to as “diameter direction”).
  • the outer peripheral surface 110d has a raceway surface 110da.
  • the outer peripheral surface 110d is recessed on the inner peripheral surface 110c side in the raceway surface 110da.
  • the raceway surface 110da has an arc shape in a cross-sectional view passing through the central axis A.
  • the raceway surface 110da is a surface that comes into contact with a rolling element (not shown).
  • the anti-orbital plane is a plane on the opposite side of the orbital plane 110da in the radial direction.
  • the inner peripheral surface 110c is an anti-track surface.
  • the amount of retained austenite on the inner peripheral surface 110c which is the anti-orbital plane, is smaller than the amount of retained austenite on the raceway surface 110da.
  • the average value of the amount of retained austenite in the steel constituting the inner ring 110 is preferably 10% by volume or less.
  • the "average value of the amount of retained austenite in the steel constituting the inner ring 110" is a plurality of points arranged at equal intervals between the raceway surface 110da and the inner peripheral surface 110c along the radial direction of the inner ring 110. It is a value obtained by integrating the distribution curve of the retained austenite amount obtained by the measurement along the circumferential direction and dividing it by the cross-sectional area of the raceway ring (inner ring 110) parallel to the circumferential direction.
  • the difference between the amount of retained austenite on the inner peripheral surface 110c and the amount of retained austenite on the raceway surface 110da is preferably 3% by volume or more.
  • the amount of retained austenite on the inner peripheral surface 110c is preferably 5% by volume or less.
  • the amount of retained austenite in the steel constituting the inner ring 110 is measured by an X-ray diffraction method. More specifically, the amount of retained austenite is obtained by comparing the intensities of the diffraction peaks of each phase obtained by irradiating with X-rays.
  • the minimum value of compressive residual stress on the raceway surface 110 da is 100 MPa or more. In the region where the distance from the raceway surface 110 da is 0.2 mm or less, the compressive residual stress is preferably 100 MPa or less.
  • the residual stress on the orbital plane 110 da is measured by the X-ray diffraction method. More specifically, the residual stress on the raceway surface 110da is measured based on the change in the diffraction peak angle when the raceway surface 110da is irradiated with X-rays.
  • the hardness on the raceway surface 110da is higher than the hardness on the inner peripheral surface 110c.
  • the hardness of the raceway surface 110da and the hardness of the inner peripheral surface 110c are preferably 700 Hv or more.
  • the hardness of the raceway surface 110da and the hardness of the inner peripheral surface 110c are measured according to the Vickers hardness test method defined in the JIS standard (JIS Z 2244: 2009).
  • FIG. 13 is a cross-sectional view of the inner ring 110 according to the modified example.
  • an immersion layer 110e may be formed on the surface of the inner ring 110.
  • the nitrogen concentration in the steel located in the immersion layer 110e is higher than the nitrogen concentration in the steel located in the steel other than the immersion layer 110e.
  • the nitrogen concentration in steel is measured by EPMA (Electron Probe Micro Analyzer).
  • the average value of the amount of retained austenite in the steel constituting the inner ring 110 is preferably 20% by volume or less.
  • FIG. 14 is a process diagram showing a manufacturing method of the inner ring 110.
  • the method for manufacturing the inner ring 110 includes a preparation step S11, a quenching step S12, a tempering step S13, and a post-treatment step S14.
  • the preparation step S11 the annular machined member 120 to be the inner ring 110 is prepared by going through the quenching step S12, the tempering step S13, and the post-treatment step S14.
  • the surface of the member 120 to be processed is subjected to a nitrification treatment prior to the quenching step S12.
  • the immersion treatment is performed by holding the member 120 to be processed at a predetermined temperature for a predetermined time in, for example, an atmospheric gas containing nitrogen (for example, ammonia (NH 3) gas).
  • the quenching step S12 the member 120 to be processed is quenched.
  • the quenching step S12 includes a heating step S121 and a cooling step S122.
  • the heating step S121 the member 120 to be processed is heated to a temperature of one A point or higher and held for a predetermined time.
  • a 1 point is the temperature at which ferrite in steel begins to transform into austenite.
  • austenite crystal grains are generated in the steel constituting the processing target member 120.
  • the cooling step S122 is performed after the heating step S121.
  • the member 120 to be processed is cooled to a temperature equal to or lower than the Ms point.
  • the Ms point is the temperature at which the transformation from austenite to martensite begins. Therefore, in the cooling step S122, some of the austenite crystal grains in the steel constituting the processing target member 120 become martensite crystal grains.
  • the temperature is lowered below the Ms point and at or near the Mf point.
  • the Mf point is the temperature at which the transformation from austenite to martensite ends. That is, in the cooling step S122, a so-called sub-zero treatment (deep cooling treatment) is performed. As a result, the amount of retained austenite in the steel constituting the work target member 120 is considerably reduced.
  • the tempering step S13 is performed after the quenching step S12. In the tempering step S13, the member 120 to be processed is tempered.
  • FIG. 15 is a schematic plan view for explaining the tempering step S13.
  • FIG. 16 is a schematic cross-sectional view for explaining the tempering step S13. As shown in FIGS. 15 and 16, the heating in the tempering step S13 is performed by, for example, induction heating.
  • the outer peripheral surface 120d of the member 120 to be processed is cooled by a cooling liquid such as water injected from the injection unit 131.
  • FIG. 17 is a graph showing the simulation results regarding the relationship between the heating time by the heating coil 130 and the temperatures on the inner peripheral surface 120c and the outer peripheral surface 120d.
  • the horizontal axis represents the heating time (unit: seconds) by the heating coil 130
  • the vertical axis represents the temperature (unit: ° C.) on the inner peripheral surface 120c and the outer peripheral surface 120d.
  • the simulation of FIG. 17 was performed under the conditions that the heating temperature of the inner peripheral surface 120c was 420 ° C., the outer peripheral surface 120d was water-cooled, and the distance between the inner peripheral surface 120c and the outer peripheral surface 120d was 3 mm.
  • the heating temperature of the outer peripheral surface 120d is lower than the heating temperature of the inner peripheral surface 120c.
  • FIG. 18 is a graph showing a simulation result of the heating temperature of the outer peripheral surface 120d when the heating temperature of the inner peripheral surface 120c is changed.
  • the horizontal axis represents the heating temperature (unit: ° C.) of the inner peripheral surface 120c
  • the vertical axis represents the heating temperature (unit: ° C.) of the outer peripheral surface 120d.
  • the simulation of FIG. 18 was performed under the same conditions as the simulation of FIG. 17, except that the heating temperature of the inner peripheral surface 120c was changed.
  • the heating temperature of the outer peripheral surface 120d is a linear expression of the heating temperature of the inner peripheral surface 120c.
  • the volume ratio (M 1 ) of retained austenite in the steel constituting the work target member 120 after the tempering step S13 is performed is tempered.
  • M 1 M 0 ⁇ ⁇ A.
  • the heating temperature of the outer peripheral surface 120d can be appropriately adjusted, and accordingly, the volume ratio of the retained austenite in the inner peripheral surface 120c. And the volume ratio of retained austenite on the outer peripheral surface 120d can be adjusted as appropriate.
  • post-treatment step S14 post-treatment is performed on the member 120 to be processed.
  • This post-treatment includes grinding of the processing target member 120, cleaning of the processing target member 120, and the like. With the above, the manufacturing process of the inner ring 110 is completed.
  • the inner ring 110 since the amount of retained austenite on the anti-orbital plane (inner peripheral surface 110c) is smaller than the amount of retained austenite on the raceway surface 110da, the retained austenite is transformed into martensite over time, so that the inner peripheral surface 110c The dimensional change of is small. Therefore, in the inner ring 110, the fitting with the shaft is hard to loosen, and the creep resistance on the anti-track surface can be improved.
  • the amount of retained austenite on the inner peripheral surface 110c is smaller than the amount of retained austenite on the raceway surface 110da (from another viewpoint, the amount of decrease in retained austenite on the inner peripheral surface 110c is the amount of retained austenite on the raceway surface 110da.
  • the shrinkage on the inner peripheral surface 110c side after the end of the tempering step S13 is larger than that on the raceway surface 110da side.
  • the raceway surface 110da Due to this difference in the amount of shrinkage, compressive residual stress acts on the raceway surface 110da.
  • the difference between the amount of retained austenite on the inner peripheral surface 110c and the amount of retained austenite on the raceway surface 110da is 3% by volume or more, so that the raceway surface 110da has a large compressive residual stress (specifically, , The minimum value is 100 MPa or more). Therefore, according to the inner ring 110, the rolling fatigue characteristics on the raceway surface 110 da can be improved.
  • the average value of the amount of retained austenite in the steel constituting the inner ring 110 is 10% by volume or less (when the nitriding layer 110e is formed, it is 20% by volume or less). , The transformation of retained austenite to martensite with the passage of time is less likely to occur, and the creep resistance can be further improved.
  • the average value of the amount of retained austenite in the steel constituting the inner ring 110 is 10% by volume or less (20% by volume when the nitriding layer 110e is formed). The following) can be used. If the average value of the amount of retained austenite in the steel is reduced before the tempering step S13, the time required for the tempering step S13 can be shortened, and the inner peripheral surface 110c is heated in the tempering step S13. The temperature can be lowered. As a result, the hardness can be maintained not only on the raceway surface 110da but also on the inner peripheral surface 110c.
  • Samples 1 to 4 were prepared as samples to be used in the experiment.
  • Samples 1 to 4 are annular members formed by SUJ2 defined in JIS standards.
  • the surfaces of Sample 1 and Sample 2 have not been subjected to nitrification treatment.
  • the surfaces of Samples 3 and 4 are subjected to a nitrogen immersion treatment.
  • the sample 1 and the sample 3 are not subjected to the sub-zero treatment in the cooling step S122, and the samples 2 and the sample 4 are subjected to the sub-zero treatment in the cooling step S122.
  • a tempering step S13 is performed on Samples 1 to 4.
  • the amount of retained austenite on the orbital surface of Sample 1 was 11% by volume.
  • the amount of retained austenite on the orbital surface of Sample 2 was 7% by volume.
  • the amount of retained austenite on the orbital surface of Sample 3 was 31% by volume, while the amount of retained austenite on the orbital surface of Sample 4 was 16% by volume.
  • the inner ring 110 is formed by performing the subzero treatment in the cooling step S122.
  • the average value of the amount of retained austenite in the steel can be 10% by volume or less (20% by volume or less when the immersion layer 110e is formed).
  • Tempering step S13 was performed on sample 2. At this time, the heating temperature on the inner peripheral surface side of the sample 2 was set to 300 ° C., and the outer peripheral surface side of the sample 2 was water-cooled. The heating time was set so that the difference between the amount of retained austenite on the outer peripheral surface and the retained austenite on the inner peripheral surface was 3% by volume based on the formulas 1 and 2.

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Abstract

Une bague interne (12) est constituée d'acier à haute teneur en carbone et comporte une surface de chemin de roulement de bague interne (12A) s'étendant le long de la direction circonférentielle et une surface circonférentielle interne (12C) qui fait office de surface circonférentielle s'étendant le long de la direction circonférentielle et s'étendant également le long de la direction axiale. La quantité d'austénite résiduelle dans la surface de chemin de roulement de bague interne (12A) est plus grande que celle présente dans la surface circonférentielle interne (12C). La différence entre la quantité d'austénite résiduelle sur la surface de chemin de roulement de bague interne (12A) et la quantité d'austénite résiduelle sur la surface circonférentielle interne (12C) est supérieure ou égale à 3% en volume.
PCT/JP2020/042944 2019-11-22 2020-11-18 Élément de chemin de roulement, palier à roulement, bague de palier pour palier à roulement, et procédé de fabrication de bague de palier pour palier à roulement WO2021100746A1 (fr)

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JP2019211179A JP2021081047A (ja) 2019-11-22 2019-11-22 軌道部材および転がり軸受
JP2019-211179 2019-11-22
JP2020000362A JP2021110341A (ja) 2020-01-06 2020-01-06 転がり軸受の軌道輪
JP2020-000362 2020-01-06

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH1193956A (ja) * 1997-09-18 1999-04-06 Nippon Seiko Kk 転がり軸受
JP2004232858A (ja) * 2003-01-08 2004-08-19 Ntn Corp ころがり軸受およびその製造方法
JP2013160314A (ja) * 2012-02-06 2013-08-19 Nsk Ltd 転がり軸受
JP2018009226A (ja) * 2016-07-14 2018-01-18 株式会社ジェイテクト 熱処理方法及び熱処理装置

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH1193956A (ja) * 1997-09-18 1999-04-06 Nippon Seiko Kk 転がり軸受
JP2004232858A (ja) * 2003-01-08 2004-08-19 Ntn Corp ころがり軸受およびその製造方法
JP2013160314A (ja) * 2012-02-06 2013-08-19 Nsk Ltd 転がり軸受
JP2018009226A (ja) * 2016-07-14 2018-01-18 株式会社ジェイテクト 熱処理方法及び熱処理装置

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