WO2000075522A1 - Bearing device and method of manufacturing the bearing device - Google Patents

Bearing device and method of manufacturing the bearing device Download PDF

Info

Publication number
WO2000075522A1
WO2000075522A1 PCT/JP2000/003614 JP0003614W WO0075522A1 WO 2000075522 A1 WO2000075522 A1 WO 2000075522A1 JP 0003614 W JP0003614 W JP 0003614W WO 0075522 A1 WO0075522 A1 WO 0075522A1
Authority
WO
WIPO (PCT)
Prior art keywords
shaft
bearing
bearing device
sleeve
stainless steel
Prior art date
Application number
PCT/JP2000/003614
Other languages
French (fr)
Japanese (ja)
Inventor
Susumu Tanaka
Tomohiro Kudo
Katuhiko Tanaka
Manabu Ohori
Original Assignee
Nsk Ltd.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Nsk Ltd. filed Critical Nsk Ltd.
Publication of WO2000075522A1 publication Critical patent/WO2000075522A1/en

Links

Classifications

    • 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
    • F16C33/02—Parts of sliding-contact bearings
    • F16C33/04—Brasses; Bushes; Linings
    • F16C33/06—Sliding surface mainly made of metal
    • F16C33/10—Construction relative to lubrication
    • F16C33/1025—Construction relative to lubrication with liquid, e.g. oil, as lubricant
    • F16C33/106—Details of distribution or circulation inside the bearings, e.g. details of the bearing surfaces to affect flow or pressure of the liquid
    • F16C33/107—Grooves for generating pressure
    • 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
    • C23C8/08—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 only one element being applied
    • C23C8/20—Carburising
    • C23C8/22—Carburising of ferrous surfaces
    • 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
    • F16C17/00—Sliding-contact bearings for exclusively rotary movement
    • F16C17/04—Sliding-contact bearings for exclusively rotary movement for axial load only
    • F16C17/045—Sliding-contact bearings for exclusively rotary movement for axial load only with grooves in the bearing surface to generate hydrodynamic pressure, e.g. spiral groove thrust bearings
    • 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
    • F16C17/00—Sliding-contact bearings for exclusively rotary movement
    • F16C17/10—Sliding-contact bearings for exclusively rotary movement for both radial and axial load
    • F16C17/102—Sliding-contact bearings for exclusively rotary movement for both radial and axial load with grooves in the bearing surface to generate hydrodynamic pressure
    • F16C17/107—Sliding-contact bearings for exclusively rotary movement for both radial and axial load with grooves in the bearing surface to generate hydrodynamic pressure with at least one surface for radial load and at least one surface for axial load
    • 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
    • F16C17/00—Sliding-contact bearings for exclusively rotary movement
    • F16C17/12—Sliding-contact bearings for exclusively rotary movement characterised by features not related to the direction of the load
    • F16C17/22—Sliding-contact bearings for exclusively rotary movement characterised by features not related to the direction of the load with arrangements compensating for thermal expansion
    • 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
    • F16C33/02—Parts of sliding-contact bearings
    • F16C33/04—Brasses; Bushes; Linings
    • F16C33/06—Sliding surface mainly made of metal
    • F16C33/12—Structural composition; Use of special materials or surface treatments, e.g. for rust-proofing
    • 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
    • F16C33/02—Parts of sliding-contact bearings
    • F16C33/04—Brasses; Bushes; Linings
    • F16C33/06—Sliding surface mainly made of metal
    • F16C33/14—Special methods of manufacture; Running-in
    • 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
    • F16C2220/00—Shaping
    • F16C2220/60—Shaping by removing material, e.g. machining
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C2223/00—Surface treatments; Hardening; Coating
    • F16C2223/10—Hardening, e.g. carburizing, carbo-nitriding
    • F16C2223/12—Hardening, e.g. carburizing, carbo-nitriding with carburizing

Definitions

  • the present invention relates to a bearing device provided with a dynamic pressure bearing (a bearing device provided with a shaft and a sleeve and generating a dynamic pressure between the two to obtain a bearing effect), and particularly for information equipment and audio / visual equipment,
  • the present invention relates to a bearing device used in a spindle motor for a magnetic disk device or an optical disk device.
  • FIG. 7 shows a conventional example of a bearing device provided with a dynamic pressure bearing.
  • the sleeve 4 has a bottom 45 that receives the lower end surface 1 a of the shaft 1.
  • the dynamic pressure grooves 4 1 and 4 2 for radial support are formed on the inner peripheral surface 4 a of the sleeve 4, and the dynamic pressure grooves 30 for axial support are formed on the lower end surface 1 a of the shaft 1. I have.
  • the sleeve 4 is a thin-walled cylinder whose inner diameter increases as the temperature rises. Therefore, if this sleeve is combined with a shaft made of the same material as the sleeve with the same coefficient of thermal expansion, the amount of increase in shaft diameter due to temperature rise will be the same as the amount of increase in sleeve inner diameter, and the operating temperature will change. However, the bearing gap does not change.
  • the sleeve 4 is made of a copper alloy having good machinability
  • the shaft 1 is made of a martensitic stainless steel having a relatively high hardness so that it is hardly damaged during handling. ing.
  • thermal expansion coefficient of copper alloy and martensitic stainless steel coefficient of linear expansion, a copper alloy: 1 7 X 1 0- 6 ⁇ 1 8 X 1 0- 6 (1 / K)
  • martensite G System stainless steel 1 0 x 1 0- 6 ⁇ : L 1 x 1 0- 6 (1 / K)
  • Japanese Patent Application Laid-Open No. H10-893445 discloses an austenitic stainless steel (wire) having a thermal expansion coefficient similar to that of a copper alloy as a shaft material. expansion coefficient: with using a 1 6 X 1 0 one 6 ⁇ 1 7 X 1 0- 6 (1 / ⁇ )), have been proposed to cure the surface of the shaft in nitriding. According to the above-mentioned publication, according to this method, the bearing gap hardly changes in accordance with a change in the operating temperature, and even if the shaft is made of a soft austenitic stainless steel, the surface hardened by nitrogen treatment can be used. However, it is described as having a hardness capable of minimizing scratch wear.
  • the surface of the shaft is hardened by nitriding, so that extremely hard chromium nitride is formed on the surface layer.
  • the corrosion resistance of the shaft surface is reduced compared to the case without nitriding.
  • the hydrodynamic bearing described in the above publication has the following problems due to the low corrosion resistance of the shaft surface.
  • the nitrided shaft surface has low corrosion resistance, and therefore, if this removal step is performed by acid cleaning, the surface may be corroded. In order to avoid corrosion, this removal process must be performed by a mechanical method.However, since the mounting thread is formed at the end of the shaft, the entire surface of the shaft is treated by a mechanical method after nitriding. This requires a great deal of time and money.
  • the present invention has been made in view of such problems of the prior art.
  • a bearing device provided with a dynamic pressure bearing a bearing gap corresponding to a change in operating temperature is provided. It consists of a combination of a copper sleeve and an austenitic stainless steel shaft with little change between the shafts, offering not only high shaft surface hardness but also excellent shaft corrosion resistance.
  • the task is to
  • Another object of the present invention is to improve the start / stop durability of a bearing device including a dynamic pressure bearing by using a shaft having a high surface hardness and a good bearing surface roughness. Disclosure of the invention
  • the present invention provides a bearing device that includes a shaft and a sleeve and generates a dynamic pressure between the two to obtain a bearing action, wherein the shaft is a solution-treated austenitic stainless steel.
  • the bearing surface of the shaft is the surface of the shaft that generates dynamic pressure in cooperation with the sleeve (by interaction with the sleeve), and if the shaft has a dynamic pressure groove, It refers to the portion of the shaft surface where the dynamic pressure groove is formed, and if the sleeve has the dynamic pressure groove, it refers to the portion of the shaft surface that contacts the dynamic pressure groove.
  • austenitic stainless steels examples include SUS303, SUS304, and SUS316. It is preferable to use SUS303 and SUS304 from the viewpoint of machinability, and to use SSUS316 from the viewpoint of corrosion resistance.
  • the bearing surface of the shaft preferably has a surface roughness (R a) of 0.30 / m or less.
  • a preferred embodiment of the bearing device of the present invention is a bearing device that includes a shaft and a sleeve, and generates a dynamic pressure between the two to obtain a bearing effect (a dynamic pressure bearing including a shaft and a sleeve that cooperates with the shaft).
  • the sleeve is made of a copper alloy
  • the shaft is formed by carburizing a shaft made of solution-treated austenitic stainless steel to form a carburized hardened layer on the surface.
  • the bearing surface of the shaft is characterized by having a surface roughness (R a) of not more than 0.30 / m and a surface hardness of not less than H v 400 by removing impurities. Things.
  • the combination of the copper sleeve and the austenitic stainless steel shaft hardly changes the bearing gap in response to changes in operating temperature, while the corrosion resistance of the shaft surface and the start-up of the bearing Hardness (Hv400 or more) and surface roughness sufficient for sliding durability at stop are ensured.
  • the present invention also provides a bearing device comprising a shaft and a sleeve, wherein a dynamic pressure is generated between the two to obtain a bearing effect, wherein the sleeve is made of a martensitic stainless steel or a brittle stainless steel; Is a case in which a carburized hardened layer is formed on the surface of a shaft made of solution-treated austenitic stainless steel by carburizing.
  • a bearing device characterized in that the bearing surface has a surface hardness of Hv 400 or more.
  • Linear expansion coefficient of martensite stainless steel and ferritic stainless steel is a 10 X 10_ 6 ⁇ 1 lxl O- 6 (1 / K), the coefficient of linear expansion of Osute Nai preparative stainless steel (1 6 x 1 0—less than 6 to 17 x 10 (1 / K)). Therefore, a bearing device equipped with a shaft made of austenitic stainless steel and a sleeve made of martensite stainless steel or ferrite stainless steel has a small bearing clearance at high temperatures, so lubrication at high temperatures It is possible to reduce a decrease in bearing rigidity due to a decrease in viscosity of the agent.
  • the carburizing treatment is performed in a carburizing gas atmosphere, for example, by heating to a temperature of 400 to 500 ° C for 10 to 50 hours.
  • Mixed gas as the carburizing gas, CO and H 2 RX gas (CO: 23%, C0 2 1%, H 2: 3 1%, H 2 0: 3 1%, a mixed gas of balance N 2) mixed gas or the like can be used between the C_ ⁇ 2 gas.
  • the carburizing process is performed by using an unsaturated hydrocarbon gas such as It is more preferable to use acetylene or ethylene under a vacuum of not more than ⁇ because a carburized hardened layer where almost no iron-based internal oxide layer is formed is formed. Further, in this method, since Cr 23 C 6 hardly precipitates in the carburized layer, a carburized hardened layer having extremely high corrosion resistance is formed. However, if the carburizing temperature exceeds 500 ° C., precipitation of Cr 23 C 6 occurs, and the corrosion resistance decreases. If the carburizing temperature is lower than 400 ° C, it takes a long time to process. In consideration of these points, the carburizing temperature is preferably set to 400 to 500 ° C.
  • the step of heating and holding in a fluorine-based gas atmosphere is preferably performed under the conditions of a heating temperature of 250 to 450 ° C. and a holding time of 10 minutes to 1 hour.
  • the fluorine gas used include fluorine compound gases such as NF 3 , BF 3 , CF 4 , HF, SF 6 , C 2 F 6 , WF 6 , CHF 3 , SiF 4 , and C 1 F 3.
  • fluorine compound gases such as NF 3 , BF 3 , CF 4 , HF, SF 6 , C 2 F 6 , WF 6 , CHF 3 , SiF 4 , and C 1 F 3.
  • Can be These gases may be used alone, but usually they are diluted with an inert gas such as N 2 gas to about 1 to 10%.
  • NF 3 is the most practical because it is gaseous at room temperature, has high chemical stability, and is easy to handle.
  • the unsaturated hydrocarbon gas it is preferable that a carburized hardened layer is formed on the surface by performing carburizing treatment at a temperature of 400 to 500 ° C. under the above atmosphere and under a vacuum of not more than 200 ° C.
  • FIG. 1 is a schematic sectional view showing a rotary device to which a bearing device according to an embodiment of the present invention is applied.
  • FIG. 2 is a graph showing the results of X-ray diffraction of the surface of No. a-4 test piece before the pickling treatment in the example.
  • FIG. 3 is a graph showing the result of X-ray diffraction of the surface of No. b-2 test piece before pickling treatment in the example.
  • FIG. 4 is a photograph showing a metal structure of a cross-section on the surface side of No. a-4 test piece before pickling treatment in the example.
  • FIG. 5 is a photograph showing a metallographic structure of a cross section on the surface side of a No. b-2 test piece before the pickling treatment in the example.
  • FIG. 6 is a graph showing the result of X-ray diffraction of the surface of No. b-7 test piece before the pickling treatment in the example.
  • FIG. 7 is a schematic sectional view showing an example of a conventional bearing device. BEST MODE FOR CARRYING OUT THE INVENTION
  • FIG. 1 is a schematic sectional view showing a rotary device to which a bearing device according to an embodiment of the present invention is applied.
  • This rotating device is a spindle motor for a magnetic disk device.
  • the lower part of a shaft 1 is fixed to a base 2, and the upper part of the shaft 1 is arranged in a sleeve 4 fitted inside a hub 3.
  • dynamic pressure grooves 41, 42 for radial support are formed on the inner peripheral surface of the sleeve 4.
  • a receiving surface 43 of a thrust plate 5 fixed to the shaft 1 is formed on an upper portion of the sleeve 4.
  • the dynamic pressure grooves 30 for axial support are formed on the upper and lower surfaces of the thrust plate 5.
  • the bearing surface of the shaft 1 is a portion of the shaft surface that comes into contact with the dynamic pressure grooves 41 and 42.
  • the upper part of this sleeve 4 is closed by a cover plate 6.
  • the cover plate 6 has a through hole 61 into which the shaft 1 is loosely fitted. The end protrudes above this through hole 61.
  • the mouth 7 is fixed to the inner peripheral surface at the lower part of the hub 3, and the stay 8 opposite thereto is fixed to the upper part of the base 2.
  • the sleeve 4 and the thrust plate 5 are made of a copper alloy having good machinability and easy to form a dynamic pressure groove by plastic working (coining).
  • the shaft 1 is formed by forming a solution-processed austenitic stainless steel into a shaft and then carburizing the shaft to form a carburized hardened layer on the surface.
  • the hub 3 is made of aluminum alloy for an aluminum disk, and made of ferritic stainless steel for a glass disk.
  • the spindle motor according to this embodiment includes a bearing device including the shaft 2 and the sleeve 4 corresponding to an embodiment of the present invention. Therefore, in this bearing device, not only is there little change in the bearing clearance according to the change in the operating temperature, but also the corrosion resistance and sufficient hardness of the shaft surface are ensured. As a result, the spindle motor of this embodiment has high reliability and durability.
  • Table 1 below shows the material of each test piece and the heat treatment method.
  • No. a—1 to a—5 and No. b— :! to b—4 are solution-treated austenitic stainless steels (solution treatment conditions: 150 ° C. After heating for 1 hour, water-cooled.) was processed into a rod having a diameter of 5 mm and a length of 5 O mm.
  • Nos. B-5 and b_6 martensite stainless steel processed into the same rod shape as described above was used.
  • a fluorine-based gas After performing the step of heating and holding under an atmosphere, carburizing treatment was performed. That is, first, a test piece was placed in a furnace, and nitrogen and nitrogen fluoride (NF
  • the mixed gas of 3 ) (NF 3 concentration 10%) was introduced and heated and maintained at a temperature of 300 to 380 ° C for 20 to 30 minutes. Then, this test piece was placed in a furnace under a mixed gas atmosphere of RX and C0 2, was subjected to carburizing treatment by holding for 40 hours pressurized heat at a temperature 450 to 500 ° C. As a result, the thickness of the hardened layer formed by carburizing becomes about 20 to 30 / m.
  • a nitriding treatment was performed by heating and holding for 48 hours. As a result, the thickness of the hardened layer formed by the nitriding treatment becomes about 20 to 30 m.
  • test piece was used without heat treatment.
  • Nos. B-5 and b-6 were kept at 950 ° C and 1050 ° C for 30 minutes, oil quenched, and tempered at 160-180 ° C for 2 hours.
  • oxide scale, nitride particles, and soot-like deposits were present on the surface in No. b_l to b-3, and the surface was blackened.
  • the inner oxide layer and soot deposits were present on the surface, and the surface was blackened.
  • Nos. A-4 and a_5 almost no internal oxide layer was observed.
  • the pickling treatment is performed to remove such internal oxide layers and surface deposits.
  • No. bl-b-3 since the base material is significantly eluted by this pickling treatment, the internal oxidation Layers and surface deposits cannot be completely removed.
  • the graph of FIG. 2 shows the result of X-ray diffraction of the surface of No. a-4 test piece before the pickling treatment. From this graph, only the peak of the austenitic stainless steel as the base metal is observed. That is, the carbon is completely dissolved in the monostenite at a concentration lower than the solid solubility limit of the monostenite.
  • Fig. 3 The graph of shows the result of X-ray diffraction of the surface of the No. b_2 test piece before the pickling treatment.
  • the photograph in Fig. 4 shows a cross section of the surface of No. a-4 specimen before pickling.
  • the photograph in Fig. 5 shows a cross section on the surface side of the No. b_2 test piece before the pickling treatment.
  • the surface is very rough, and in addition to clearly seeing the boundary between the compound layer and the base material, cracks and the like are also observed.
  • the surface is gentle and no boundary between the compound layer and the base material is recognized.
  • No. b— After the above heat treatment and pickling treatment, No. b— :! The test pieces of Nos. B-4 to b-6 were not subjected to the pickling treatment after the heat treatment described above, and the test pieces of Nos. B-4 to b-6 were finished by grinding. Each test piece after the processing was subjected to a salt spray test for 2 hours in accordance with JISZ2371. For No. b-7, an annealed SUS303 (without solution treatment) processed into the same rod shape as the other test pieces was prepared. — After the same heat treatment and pickling treatment as in 3, use the same grinding Finishing was performed and a salt spray test was performed under the same conditions.
  • the graph in Fig. 6 shows the result of X-ray diffraction of the surface of No. b-7 specimen before the pickling treatment. From this graph, in addition to the peak of the austenitic stainless steel as the base metal, peaks such as (Cr, Fe) aC and Hiichi Fe are observed. From this result, even if austenitic stainless steel is not used, the reaction between ferrite and carburizing gas occurs during carburizing, and (Cr, Fe) 3 C precipitates unless a solution-treated product is used. I understand.
  • the bearing device equipped with a shaft corresponding to test piece No. a-l to a-5 and a copper alloy sleeve has almost no change in bearing clearance according to the change in operating temperature.
  • the corrosion resistance and sufficient hardness of the shaft surface are ensured, so that the equipment has high reliability and durability.
  • a bearing device equipped with a shaft obtained in the same manner as that of the test pieces No. a-4 and a-5 subjected to vacuum carburization can eliminate the pickling process of the shaft, and therefore the work process There is also an effect that the number can be reduced.
  • the sleeve is made of a copper alloy.
  • the bearing gap is slightly reduced at high temperatures, so In this case, it is possible to reduce a decrease in bearing rigidity due to a decrease in viscosity of the lubricant.
  • the sleeve and the hub are made of stainless steel integrally, and the shaft is made of solution-treated austenitic stainless steel to reduce the bearing stiffness at high temperatures. It can be even smaller.
  • the shaft diameter was 6 mm, and the bearing width (the axial dimension of both hydrodynamic grooves 41 and 42) was 6 mm.
  • the lubricating oil was diester oil and the rotation speed was 7200 rpm.
  • SUS 3 1 6 16. 0 1 0 6 (1 / K).
  • the rotating device shown in Fig. 1 was assembled by combining the shaft and sleeve shown in Table 3.
  • the shaft diameter is 6 mm
  • the bearing width is 6 mm.
  • the shafts of Nos. 21, 22, and 26 were manufactured by using the same SUS303 solution-processed product as a-3 described above and performing the same treatment as a-3.
  • the shaft of No. 23 was prepared by using the same solution-processed SUS 304 as the above-mentioned a-1 and performing the same processing as a-1.
  • the shafts of Nos. 24 and 25 were manufactured using the same solution-processed SUS316 as in a-5 described above, and subjected to the same processing as a-5.
  • the shaft of No. 27 used the same solution-processed SUS303 as b-4 described above, and was used without heat treatment as in b-4.
  • the shaft of No. 28 was manufactured by using the same SUS420J2 as b-5 described above and performing the same processing as b-5.
  • the shaft of No. 29 was manufactured using the same SUS440C as in b-6 described above and by performing the same processing as in b-6.
  • This rotating device was placed sideways, and the rotating device was started and stopped 300,000 times under the conditions of a radial load of 1 N and a rotation speed of 7200 rpm using diester oil as a lubricating oil.
  • Table 3 also shows the observation results.
  • “X” indicates that the degree of damage was extremely large, and “ ⁇ ” indicates that almost no damage occurred.
  • the shaft was made of stainless steel and the sleeve was made of a copper alloy. Are almost the same. In Nos.
  • the shaft is made of austenitic stainless steel and the sleeve is made of ferritic stainless steel, and the thermal expansion coefficient of the sleeve is smaller than that of the shaft.
  • the shaft is made of martensite stainless steel and the sleeve is made of a copper alloy, and the thermal expansion coefficient of the sleeve is larger than that of the shaft.
  • the temperature characteristic value is largest in the combination (No. 22, 25) where the thermal expansion coefficient of the sleeve is smaller than the thermal expansion coefficient of the shaft, and the thermal expansion coefficient of the shaft and the sleeve is almost the same.
  • the same combination (Nos. 21, 23, 24, 26, 27) and the combination (No. 28, 29) with the sleeve's thermal expansion coefficient larger than the shaft's thermal expansion coefficient become smaller.
  • the bearing device of the present invention corrosion resistance and sufficient hardness of the shaft surface are ensured while the shaft is made of austenitic stainless steel having a thermal expansion coefficient substantially equal to that of a copper alloy. .
  • the shaft has a high surface hardness and a good roughness of the bearing surface of the shaft, so that the bearing has excellent durability in starting and stopping and also has excellent corrosion resistance in the shaft. Bearing device is obtained.
  • the bearing gap hardly changes according to the change in the operating temperature.
  • the corrosion resistance and sufficient hardness of the shaft surface are ensured, so that the reliability and durability of the equipment are high.
  • the rigidity of the bearing at high temperatures can be improved by using a combination in which the thermal expansion coefficient of the sleeve is smaller than the thermal expansion coefficient of the shaft.

Landscapes

  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Sliding-Contact Bearings (AREA)
  • Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)

Abstract

A bearing device having dynamic pressure bearing with less variation in bearing clearance according to a variation in service temperature and a corrosiveness and a sufficient hardness on the surface of a shaft, wherein a sleeve (4) is made of copper alloy, a solution-heat-treated austenitic stainless steel is used as the material of the shaft (1) and, after the stainless steel is machined in a shaft body, a carburization treatment is applied to the shaft body so as to form a carburized hard layer on the surface of the shaft, and then the shaft high in surface hardness and excellent in bearing surface roughness is used so as to increase the durability of the bearing device with dynamic pressure bearing against starting and stopping, and also the coefficient of thermal expansion of the material forming the sleeve is reduced to below that of the material forming the shaft so as to improve the rigidity of the bearing at high temperatures.

Description

明 細 書 軸受装置およびその製造方法 技術分野  Description Bearing device and its manufacturing method
この発明は、 動圧軸受を備えた軸受装置 （軸とスリーブとを備え、 両 者の間に動圧を生じさせて軸受作用を得る軸受装置） に関し、 情報機器 や音響 ·映像機器用、 特に、 磁気ディスク装置や光ディスク装置用のス ピンドルモー夕に使用する軸受装置として好適なものに関する。 背景技術  The present invention relates to a bearing device provided with a dynamic pressure bearing (a bearing device provided with a shaft and a sleeve and generating a dynamic pressure between the two to obtain a bearing effect), and particularly for information equipment and audio / visual equipment, The present invention relates to a bearing device used in a spindle motor for a magnetic disk device or an optical disk device. Background art
図 7は、 動圧軸受を備えた軸受装置の従来例である。 この軸受装置に おいて、 スリーブ 4は、 軸 1の下端面 1 aを受ける底部 4 5を備えてい る。 この例では、 ラジアル支持用の動圧溝 4 1 , 4 2がスリーブ 4の内 周面 4 aに形成され、 アキシャル支持用の動圧溝 3 0が軸 1の下端面 1 aに形成されている。  FIG. 7 shows a conventional example of a bearing device provided with a dynamic pressure bearing. In this bearing device, the sleeve 4 has a bottom 45 that receives the lower end surface 1 a of the shaft 1. In this example, the dynamic pressure grooves 4 1 and 4 2 for radial support are formed on the inner peripheral surface 4 a of the sleeve 4, and the dynamic pressure grooves 30 for axial support are formed on the lower end surface 1 a of the shaft 1. I have.
このスリーブ 4は、 温度上昇によって内径が大きくなる薄肉円筒であ る。 したがって、 このスリーブを、 熱膨張係数がこのスリーブと同じ材 料からなる軸と組み合わせれば、 温度上昇による軸径の増大量とスリー ブ内径の増大量が同じになるため、 使用温度が変化しても軸受隙間は変 ィ匕しない。  The sleeve 4 is a thin-walled cylinder whose inner diameter increases as the temperature rises. Therefore, if this sleeve is combined with a shaft made of the same material as the sleeve with the same coefficient of thermal expansion, the amount of increase in shaft diameter due to temperature rise will be the same as the amount of increase in sleeve inner diameter, and the operating temperature will change. However, the bearing gap does not change.
通常、 このスリーブ 4は、 切削性の良好な銅合金で作製されており、 軸 1は、 取り扱い時に傷がつき難くするために、 比較的高い硬度が得ら れるマルテンサイ ト系ステンレス鋼で作製されている。 ここで、 銅合金 とマルテンサイ ト系ステンレス鋼で熱膨張係数に差がある （線膨張係数 で、 銅合金： 1 7 X 1 0— 6〜 1 8 X 1 0— 6 ( 1 /K ) 、 マルテンサイ ト 系ステンレス鋼： 1 0 x 1 0—6〜： L 1 x 1 0—6 ( 1 /K ) ) ため、 この 軸受装置には、 使用温度の変化によって軸受隙間が変化する、 すなわち 軸受性能が変化するという問題点がある。 Usually, the sleeve 4 is made of a copper alloy having good machinability, and the shaft 1 is made of a martensitic stainless steel having a relatively high hardness so that it is hardly damaged during handling. ing. Here, in there is a difference in thermal expansion coefficient of copper alloy and martensitic stainless steel (coefficient of linear expansion, a copper alloy: 1 7 X 1 0- 6 ~ 1 8 X 1 0- 6 (1 / K), martensite G System stainless steel: 1 0 x 1 0- 6 ~ : L 1 x 1 0- 6 (1 / K)) Accordingly, the bearing device, the bearing clearance is changed by a change in operating temperature, i.e. bearing performance change There is a problem that.
この問題点を解決するために、 日本国特開平 1 0— 8 9 3 4 5号公報 には、 軸の材料として、 熱膨張係数が銅合金に近似しているオーステナ ィ ト系ステンレス鋼 （線膨張係数： 1 6 X 1 0一6〜 1 7 X 1 0—6 ( 1 / Κ ) ) を使用するとともに、 軸の表面を窒化処理で硬化することが提案 されている。 上記公報には、 この方法によれば、 使用温度の変化に応じ た軸受隙間の変化がほとんど生じないとともに、 軟質なオーステナイ ト 系ステンレス鋼製の軸であっても、 窒素処理で硬化された表面がひっか き摩耗を軽微にできる硬度になる、 と記載されている。 In order to solve this problem, Japanese Patent Application Laid-Open No. H10-893445 discloses an austenitic stainless steel (wire) having a thermal expansion coefficient similar to that of a copper alloy as a shaft material. expansion coefficient: with using a 1 6 X 1 0 one 6 ~ 1 7 X 1 0- 6 (1 / Κ)), have been proposed to cure the surface of the shaft in nitriding. According to the above-mentioned publication, according to this method, the bearing gap hardly changes in accordance with a change in the operating temperature, and even if the shaft is made of a soft austenitic stainless steel, the surface hardened by nitrogen treatment can be used. However, it is described as having a hardness capable of minimizing scratch wear.
しかしながら、 上記公報に記載の方法では、 窒化処理により軸の表面 硬化を行っているため、 表面層に非常に硬質なクロム窒化物が形成され る。 その結果、 軸表面の耐食性は、 窒化処理しない場合と比較して低下 する。 また、 上記公報に記載された動圧軸受には、 軸表面の耐食性が低 いことに伴って、 以下のような問題点もある。  However, in the method described in the above publication, the surface of the shaft is hardened by nitriding, so that extremely hard chromium nitride is formed on the surface layer. As a result, the corrosion resistance of the shaft surface is reduced compared to the case without nitriding. Further, the hydrodynamic bearing described in the above publication has the following problems due to the low corrosion resistance of the shaft surface.
すなわち、 窒化処理された軸表面には酸化スケールや窒化物粒子が存 在するため、 これらが脱落して軸受隙間に入り込まないように、 後工程 でこれらを除去する必要がある。 ここで、 上述のように、 窒化処理され た軸表面は耐食性が低いため、 この除去工程を酸洗浄で行うと表面が腐 食する恐れがある。 腐食を避けるためには、 この除去工程を機械的方法 によって行う必要があるが、 軸の端部には取付用ねじ溝が形成されてい るため、 窒化処理後に軸の全面を機械的方法によって処理するには多大 な時間と費用が必要である。  That is, since oxide scale and nitride particles are present on the shaft surface subjected to the nitriding treatment, it is necessary to remove them in a subsequent step so that they do not fall off and enter the bearing gap. Here, as described above, the nitrided shaft surface has low corrosion resistance, and therefore, if this removal step is performed by acid cleaning, the surface may be corroded. In order to avoid corrosion, this removal process must be performed by a mechanical method.However, since the mounting thread is formed at the end of the shaft, the entire surface of the shaft is treated by a mechanical method after nitriding. This requires a great deal of time and money.
本発明は、 このような従来技術の問題点に着目してなされたものであ り、 動圧軸受を備えた軸受装置として、 使用温度の変化に応じた軸受隙 間の変化がほとんどない、 銅製のスリーブとオーステナイ ト系ステンレ ス鋼製の軸との組合せで構成されていて、 軸の表面硬度が高いだけでな く、 軸の耐食性にも優れたものを提供することを課題とする。 The present invention has been made in view of such problems of the prior art. As a bearing device provided with a dynamic pressure bearing, a bearing gap corresponding to a change in operating temperature is provided. It consists of a combination of a copper sleeve and an austenitic stainless steel shaft with little change between the shafts, offering not only high shaft surface hardness but also excellent shaft corrosion resistance. The task is to
本発明は、 また、 表面硬度が高く且つ軸受面の粗さが良好な軸を用い ることによって、 動圧軸受を備えた軸受装置の起動停止耐久性を良好に することを課題とする。 発明の開示  Another object of the present invention is to improve the start / stop durability of a bearing device including a dynamic pressure bearing by using a shaft having a high surface hardness and a good bearing surface roughness. Disclosure of the invention
上記課題を解決するために、 本発明は、 軸とスリーブとを備え、 両者 の間に動圧を生じさせて軸受作用を得る軸受装置において、 前記軸は、 溶体化処理されたオーステナイ 卜系ステンレス鋼からなる軸状体に浸炭 処理を施すことにより表面に浸炭硬化層が形成されたものであり、 この 軸の軸受面の表面硬さは H v 4 0 0以上であることを特徴とする軸受装 置を提供する。  In order to solve the above-mentioned problems, the present invention provides a bearing device that includes a shaft and a sleeve and generates a dynamic pressure between the two to obtain a bearing action, wherein the shaft is a solution-treated austenitic stainless steel. A bearing in which a carburized hardened layer is formed on the surface by subjecting a steel shaft to a carburizing treatment, and the bearing surface of the shaft has a surface hardness of Hv400 or more. Provide equipment.
軸の軸受面とは、 スリーブと共働して （スリーブとの相互作用によつ て） 動圧が生じる軸の表面のことであって、 軸に動圧溝が形成されてい る場合には、 軸表面の動圧溝が形成されている部分を指し、 スリーブに 動圧溝が形成してある場合には、 軸表面の前記動圧溝と接触する部分を 指す。  The bearing surface of the shaft is the surface of the shaft that generates dynamic pressure in cooperation with the sleeve (by interaction with the sleeve), and if the shaft has a dynamic pressure groove, It refers to the portion of the shaft surface where the dynamic pressure groove is formed, and if the sleeve has the dynamic pressure groove, it refers to the portion of the shaft surface that contacts the dynamic pressure groove.
オーステナイ ト系ステンレス鋼としては、 S U S 3 0 3、 S U S 3 0 4、 S U S 3 1 6等が挙げられる。 切削性の点からは S U S 3 0 3や S U S 3 0 4を使用することが、 耐食性の点からは S U S 3 1 6を使用す ることが好ましい。  Examples of austenitic stainless steels include SUS303, SUS304, and SUS316. It is preferable to use SUS303 and SUS304 from the viewpoint of machinability, and to use SSUS316 from the viewpoint of corrosion resistance.
溶体化処理されていないオーステナィ ト系ステンレス鋼はフェライ ト 量が多いため、 このフェライ トと浸炭ガスが反応して M 3 Cの析出が生 じて、 耐食性が低下したり、 十分な硬さが得られない恐れがある。 本発 明では、 軸の材料として、 溶体化処理されたオーステナイ ト系ステンレ ス鋼を使用しているため、 上述のような M 3 Cの析出が抑制される。 ま た、 表面硬化を窒化処理ではなく浸炭処理によって行っているため、 軸 表面にクロム窒化物が生じ難い。 For Osutenai DOO stainless steel that has not been treated solution is often ferrite amount, by Ji raw is M 3 C precipitation the ferrite and carburizing gas reacts, or reduction in the corrosion resistance, sufficient hardness There is a possibility that it cannot be obtained. Departure In the bright, as the material of the shaft, due to the use of austenitic stainless steel treated solution, M 3 C precipitation as described above it is suppressed. In addition, since the surface hardening is performed by carburizing instead of nitriding, chromium nitride hardly occurs on the shaft surface.
したがって、 この軸受装置によれば、 軸表面の耐食性と十分な硬さが 確保される。  Therefore, according to this bearing device, corrosion resistance and sufficient hardness of the shaft surface are ensured.
この軸受装置において、 前記軸の軸受面の表面粗さ （R a ) は 0 . 3 0 / m以下であることが好ましい。 これにより、 動圧軸受の起動停止時 の摺動耐久性が良好となる。  In this bearing device, the bearing surface of the shaft preferably has a surface roughness (R a) of 0.30 / m or less. Thereby, the sliding durability at the time of starting and stopping the dynamic pressure bearing is improved.
本発明の軸受装置の好ましい形態は、 軸とスリーブとを備え、 両者の 間に動圧を生じさせて軸受作用を得る軸受装置 （軸とこの軸と共働する スリーブとを備えた動圧軸受装置） において、 前記スリーブは銅合金か らなり、 前記軸は、 溶体化処理されたオーステナィ ト系ステンレス鋼か らなる軸状体に浸炭処理を施すことによって、 表面に浸炭硬化層が形成 されたものであり、 軸の軸受面は、 不純物除去加工されて表面粗さ （R a ) が 0 . 3 0 / m以下に表面硬さが H v 4 0 0以上になっていること を特徴とするものである。  A preferred embodiment of the bearing device of the present invention is a bearing device that includes a shaft and a sleeve, and generates a dynamic pressure between the two to obtain a bearing effect (a dynamic pressure bearing including a shaft and a sleeve that cooperates with the shaft). In the apparatus, the sleeve is made of a copper alloy, and the shaft is formed by carburizing a shaft made of solution-treated austenitic stainless steel to form a carburized hardened layer on the surface. The bearing surface of the shaft is characterized by having a surface roughness (R a) of not more than 0.30 / m and a surface hardness of not less than H v 400 by removing impurities. Things.
この軸受装置によれば、 銅製のスリーブとオーステナイ ト系ステンレ ス鋼製の軸との組合せによって、 使用温度の変化に応じた軸受隙間の変 化がほとんどないとともに、 軸表面の耐食性と軸受の起動停止時の摺動 耐久性に十分な硬さ （H v 4 0 0以上） 及び表面粗さが確保される。 本発明はまた、 軸とスリーブとを備え、 両者の間に動圧を生じさせて 軸受作用を得る軸受装置において、 前記スリーブはマルテンサイ ト系ス テンレス鋼またはフヱライ ト系ステンレス鋼からなり、 前記軸は、 溶体 化処理されたオーステナイ ト系ステンレス鋼からなる軸状体に浸炭処理 を施すことにより表面に浸炭硬化層が形成されたものであり、 この軸の 軸受面の表面硬さが Hv 400以上であることを特徴とする軸受装置を 提供する。 According to this bearing device, the combination of the copper sleeve and the austenitic stainless steel shaft hardly changes the bearing gap in response to changes in operating temperature, while the corrosion resistance of the shaft surface and the start-up of the bearing Hardness (Hv400 or more) and surface roughness sufficient for sliding durability at stop are ensured. The present invention also provides a bearing device comprising a shaft and a sleeve, wherein a dynamic pressure is generated between the two to obtain a bearing effect, wherein the sleeve is made of a martensitic stainless steel or a brittle stainless steel; Is a case in which a carburized hardened layer is formed on the surface of a shaft made of solution-treated austenitic stainless steel by carburizing. A bearing device characterized in that the bearing surface has a surface hardness of Hv 400 or more.
マルテンサイ ト系ステンレス鋼およびフェライ ト系ステンレス鋼の線 膨張係数は 10 X 10_6〜1 l x l O—6 ( 1/K) であって、 オーステ ナイ ト系ステンレス鋼の線膨張係数 （ 1 6 x 1 0— 6〜1 7 x 10 ( 1 /K) ) より小さい。 したがって、 オーステナイ ト系ステンレス鋼から なる軸と、 マルテンサイ ト系ステンレス鋼またはフェライ ト系ステンレ ス鋼からなるスリーブとを備えた軸受装置は、 高温時に軸受隙間が僅か に減少するため、 高温時の潤滑剤の粘度低下による軸受剛性の低下を少 なくすることができる。 Linear expansion coefficient of martensite stainless steel and ferritic stainless steel is a 10 X 10_ 6 ~1 lxl O- 6 (1 / K), the coefficient of linear expansion of Osute Nai preparative stainless steel (1 6 x 1 0—less than 6 to 17 x 10 (1 / K)). Therefore, a bearing device equipped with a shaft made of austenitic stainless steel and a sleeve made of martensite stainless steel or ferrite stainless steel has a small bearing clearance at high temperatures, so lubrication at high temperatures It is possible to reduce a decrease in bearing rigidity due to a decrease in viscosity of the agent.
浸炭処理は、 浸炭ガス雰囲気下で、 例えば温度 400〜500°Cに 1 0〜50時間加熱することにより行われる。 浸炭用ガスとしては、 CO と H2 との混合ガス、 RXガス （CO ： 23%、 C02 1 %、 H2 ： 3 1 %、 H2 0 : 3 1 %、 残部 N2 の混合ガス） と C〇2 ガスとの混合ガ ス等が使用できる。 The carburizing treatment is performed in a carburizing gas atmosphere, for example, by heating to a temperature of 400 to 500 ° C for 10 to 50 hours. Mixed gas as the carburizing gas, CO and H 2, RX gas (CO: 23%, C0 2 1%, H 2: 3 1%, H 2 0: 3 1%, a mixed gas of balance N 2) mixed gas or the like can be used between the C_〇 2 gas.
ただし、 400〜500°Cで C〇を含む雰囲気下では、 浸炭 （2 C→ C〇2 +C) と同時に、 F eの酸化 （ 4 C 0+ 3 F e→4 C O + F e 3 〇4 ) も生じるため、 表面から 2~3〃mの部分に鉄系内部酸化層が形 成されて表面が黒くなる。 そのため、 浸炭処理後に、 鉄系内部酸化層或 いは煤等の不純物を除去する目的で、 酸洗い処理を行うことが好ましい 。 また、 相手スリープと接触する軸の軸受面の粗さ （Ra) が 0. 30 zm以下となるように、 仕上げ研削およびバレル研磨 （不純物除去加工 ) を行うことが好ましい。 このバレル研磨により表面の不純物 （黒皮） も除去される。 なお、 軸の軸受面の粗さ （Ra) が 0. 30〃mを超え ると、 軸受の起動停止耐久性が低下する。 However, 400 to 500 in an atmosphere containing C_〇 in ° C, carburizing (2 C → C_〇 2 + C) at the same time, F oxidation of e (4 C 0+ 3 F e → 4 CO + F e 3 〇 4 ) also occurs, so that an iron-based internal oxide layer is formed at a portion 2 to 3 mm from the surface, and the surface becomes black. Therefore, it is preferable to perform pickling treatment after the carburizing treatment in order to remove impurities such as an iron-based internal oxide layer or soot. Further, it is preferable to perform finish grinding and barrel polishing (impurity removal processing) so that the roughness (Ra) of the bearing surface of the shaft that comes into contact with the partner sleep is 0.30 zm or less. By this barrel polishing, impurities (black scale) on the surface are also removed. If the roughness (Ra) of the bearing surface of the shaft exceeds 0.30 起動 m, the durability for starting and stopping the bearing will decrease.
一方、 浸炭処理工程を、 浸炭ガスとして不飽和炭化水素ガス、 例えば アセチレンやエチレンを使用し、 ΙΤΟΓΓ以下の真空下で行うと、 前記鉄 系内部酸化層がほとんど生じない浸炭硬化層が形成されるためより好ま しい。 また、 この方法では、 浸炭層に C r23C6 が析出し難いため、 耐 食性の非常に高い浸炭硬化層が形成される。 ただし、 浸炭処理温度が 5 00 °Cを超えると Cr23C6 の析出が生じるようになって、 耐食性が低 下する。 また、 浸炭処理温度が 400°C未満であると処理に時間がかか る。 これらの点を考慮すると、 浸炭処理温度は 4 0 0〜5 0 0°Cとする ことが好ましい。 On the other hand, the carburizing process is performed by using an unsaturated hydrocarbon gas such as It is more preferable to use acetylene or ethylene under a vacuum of not more than ΙΤΟΓΓ because a carburized hardened layer where almost no iron-based internal oxide layer is formed is formed. Further, in this method, since Cr 23 C 6 hardly precipitates in the carburized layer, a carburized hardened layer having extremely high corrosion resistance is formed. However, if the carburizing temperature exceeds 500 ° C., precipitation of Cr 23 C 6 occurs, and the corrosion resistance decreases. If the carburizing temperature is lower than 400 ° C, it takes a long time to process. In consideration of these points, the carburizing temperature is preferably set to 400 to 500 ° C.
また、 浸炭処理の前に、 フッ素系ガス雰囲気下で加熱保持する工程を 行うことが好ましい。 フッ素系ガス雰囲気下で加熱保持する工程は、 加 熱温度 2 5 0〜4 5 0°C、 保持時間 1 0分〜 1時間の条件で行うことが 好ましい。 使用するフッ素ガスとしては、 NF3 、 BF3 、 CF4 、 H F、 S F6 、 C2 F6 、 WF6 、 CHF3 、 S i F4 、 C 1 F3 等のフ ッ素化合物ガスが挙げられる。 これらのガスを単独で用いても良いが、 通常は N2 ガス等の不活性ガスで 1 ~ 1 0 %程度に希釈して使用する。 このうち、 NF3 は常温でガス状であって、 化学的安定性が高く、 取り 扱いが容易であるため、 最も実用的である。 Before the carburizing treatment, it is preferable to perform a step of heating and holding in a fluorine-based gas atmosphere. The step of heating and holding in a fluorine-based gas atmosphere is preferably performed under the conditions of a heating temperature of 250 to 450 ° C. and a holding time of 10 minutes to 1 hour. Examples of the fluorine gas used include fluorine compound gases such as NF 3 , BF 3 , CF 4 , HF, SF 6 , C 2 F 6 , WF 6 , CHF 3 , SiF 4 , and C 1 F 3. Can be These gases may be used alone, but usually they are diluted with an inert gas such as N 2 gas to about 1 to 10%. Of these, NF 3 is the most practical because it is gaseous at room temperature, has high chemical stability, and is easy to handle.
以上のことから、 本発明の軸受装置において、 前記軸は、 フッ素系ガ ス雰囲気下で 2 5 0-4 5 0°Cに 1 0分〜 1時間保持された後に、 不飽 和炭化水素ガスの雰囲気下且つ Ι ΤΟΓΓ以下の真空下で、 温度 4 0 0〜5 00°Cで浸炭処理を行うことにより表面に浸炭硬化層が形成されたもの であることが好ましい。 図面の簡単な説明  From the above, in the bearing device of the present invention, after the shaft is kept at 250 to 450 ° C. for 10 minutes to 1 hour in a fluorine-based gas atmosphere, the unsaturated hydrocarbon gas It is preferable that a carburized hardened layer is formed on the surface by performing carburizing treatment at a temperature of 400 to 500 ° C. under the above atmosphere and under a vacuum of not more than 200 ° C. BRIEF DESCRIPTION OF THE FIGURES
図 1は、 本発明の一実施形態に相当する軸受装置が適用された回転装 置を示す概略断面図である。 図 2は、 実施例において、 酸洗い処理前の No. a— 4試験片の表面を X線回折した結果を示すグラフである。 FIG. 1 is a schematic sectional view showing a rotary device to which a bearing device according to an embodiment of the present invention is applied. FIG. 2 is a graph showing the results of X-ray diffraction of the surface of No. a-4 test piece before the pickling treatment in the example.
図 3は、 実施例において、 酸洗い処理前の No. b— 2試験片の表面を X線回折した結果を示すグラフである。  FIG. 3 is a graph showing the result of X-ray diffraction of the surface of No. b-2 test piece before pickling treatment in the example.
図 4は、 実施例において、 酸洗い処理前の No. a— 4試験片の表面側 の断面の金属組織を示す写真である。  FIG. 4 is a photograph showing a metal structure of a cross-section on the surface side of No. a-4 test piece before pickling treatment in the example.
図 5は、 実施例において、 酸洗い処理前の No. b— 2試験片の表面側 の断面の金属組織を示す写真である。  FIG. 5 is a photograph showing a metallographic structure of a cross section on the surface side of a No. b-2 test piece before the pickling treatment in the example.
図 6は、 実施例において、 酸洗い処理前の No. b— 7試験片の表面を X線回折した結果を示すグラフである。  FIG. 6 is a graph showing the result of X-ray diffraction of the surface of No. b-7 test piece before the pickling treatment in the example.
図 7は、 従来の軸受装置の一例を示す概略断面図である。 発明を実施するための最良の形態  FIG. 7 is a schematic sectional view showing an example of a conventional bearing device. BEST MODE FOR CARRYING OUT THE INVENTION
以下、 本発明の実施形態について説明する。  Hereinafter, embodiments of the present invention will be described.
図 1は、 本発明の一実施形態に相当する軸受装置が適用された回転装 置を示す概略断面図である。  FIG. 1 is a schematic sectional view showing a rotary device to which a bearing device according to an embodiment of the present invention is applied.
この回転装置は、 磁気ディスク装置用のスピンドルモー夕であり、 軸 1の下部がベース 2に固定され、 この軸 1の上部は、 ハブ 3に内嵌され たスリーブ 4内に配置されている。 スリーブ 4の内周面には、 ラジアル 支持用の動圧溝 4 1 , 4 2が形成されている。 スリーブ 4の上部には、 軸 1に固定されたスラストプレート 5の受け面 4 3が形成されている。 アキシャル支持用の動圧溝 3 0は、 スラストプレ一ト 5の上下面に形成 されている。 この軸 1の軸受面は、 軸の表面のうち動圧溝 4 1 , 4 2と 接触する部分である。  This rotating device is a spindle motor for a magnetic disk device. The lower part of a shaft 1 is fixed to a base 2, and the upper part of the shaft 1 is arranged in a sleeve 4 fitted inside a hub 3. On the inner peripheral surface of the sleeve 4, dynamic pressure grooves 41, 42 for radial support are formed. A receiving surface 43 of a thrust plate 5 fixed to the shaft 1 is formed on an upper portion of the sleeve 4. The dynamic pressure grooves 30 for axial support are formed on the upper and lower surfaces of the thrust plate 5. The bearing surface of the shaft 1 is a portion of the shaft surface that comes into contact with the dynamic pressure grooves 41 and 42.
このスリーブ 4の上部はカバープレート 6で塞がれている。 このカバ 一プレート 6には軸 1が遊嵌される貫通穴 6 1が設けてあり、 軸 1の上 端部はこの貫通穴 6 1より上部に突出している。 ハブ 3の下部の内周面 に口一夕 7が固定されており、 これに対向するステ一夕 8がベース 2の 上部に固定されている。 The upper part of this sleeve 4 is closed by a cover plate 6. The cover plate 6 has a through hole 61 into which the shaft 1 is loosely fitted. The end protrudes above this through hole 61. The mouth 7 is fixed to the inner peripheral surface at the lower part of the hub 3, and the stay 8 opposite thereto is fixed to the upper part of the base 2.
スリーブ 4およびスラストプレート 5は、 切削性が良好で、 塑性加工 (コイニング） による動圧溝の形成が容易な銅合金で作製されている。 軸 1は、 溶体化処理されたオーステナィ ト系ステンレス鋼を軸状に形成 した後、 これに浸炭処理を施すことによって、 表面に浸炭硬化層が形成 されたものである。 ハブ 3は、 アルミ製ディスク用の場合にはアルミ二 ゥム合金製のものを、 ガラス製ディスク用の場合にはフェライ ト系ステ ンレス鋼製のものを使用する。  The sleeve 4 and the thrust plate 5 are made of a copper alloy having good machinability and easy to form a dynamic pressure groove by plastic working (coining). The shaft 1 is formed by forming a solution-processed austenitic stainless steel into a shaft and then carburizing the shaft to form a carburized hardened layer on the surface. The hub 3 is made of aluminum alloy for an aluminum disk, and made of ferritic stainless steel for a glass disk.
したがって、 この実施形態のスピンドルモー夕は、 本発明の一実施形 態に相当する軸 2とスリーブ 4とを備えた軸受装置を備えている。 その ため、 この軸受装置には、 使用温度の変化に応じた軸受隙間の変化がほ とんどないばかりでなく、 軸表面の耐食性と十分な硬さが確保される。 その結果、 この実施形態のスピンドルモー夕は、 信頼性および耐久性が 高いものとなる。  Therefore, the spindle motor according to this embodiment includes a bearing device including the shaft 2 and the sleeve 4 corresponding to an embodiment of the present invention. Therefore, in this bearing device, not only is there little change in the bearing clearance according to the change in the operating temperature, but also the corrosion resistance and sufficient hardness of the shaft surface are ensured. As a result, the spindle motor of this embodiment has high reliability and durability.
[軸の品質評価試験]  [Shaft quality evaluation test]
本発明の軸受装置を構成する軸の性能を具体的に説明するために、 以 下に示すような、 試験片を用いた軸の品質評価試験を行った。  In order to specifically explain the performance of the shaft constituting the bearing device of the present invention, a shaft quality evaluation test using a test piece as shown below was performed.
各試験片の材料および熱処理方法を下記の表 1に示す。 試験片として は、 No. a— 1〜a— 5 , No. b—：!〜 b— 4では、 オーステナィ ト系 ステンレス鋼の溶体化処理品 （溶体化処理条件： 1 0 5 0 °Cで 1時間加 熱後、 水冷。 ） を、 直径 5 mmで長さ 5 O mmの棒状に加工したものを 使用した。 No. b— 5 , b _ 6では、 マルテンサイ ト系ステンレス鋼を 前記と同じ棒状に加工したものを使用した。  Table 1 below shows the material of each test piece and the heat treatment method. For the test specimens, No. a—1 to a—5 and No. b— :! to b—4 are solution-treated austenitic stainless steels (solution treatment conditions: 150 ° C. After heating for 1 hour, water-cooled.) Was processed into a rod having a diameter of 5 mm and a length of 5 O mm. In Nos. B-5 and b_6, martensite stainless steel processed into the same rod shape as described above was used.
No. a— l〜a _ 3については、 先ず、 試験片に対してフッ素系ガス 雰囲気下で加熱保持する工程を行った後に、 浸炭処理を行った。 すなわ ち、 先ず、 炉内に試験片を入れて、 この炉内に窒素とフッ化窒素 （NFFor No. a—l to a_3, first, a fluorine-based gas After performing the step of heating and holding under an atmosphere, carburizing treatment was performed. That is, first, a test piece was placed in a furnace, and nitrogen and nitrogen fluoride (NF
3 ) の混合ガス （NF3 濃度 10%) を導入し、 温度 300〜380°C に 20〜30分間加熱保持した。 次に、 この試験片を、 RXと C02 の 混合ガス雰囲気下の炉内に入れて、 温度 450〜500°Cで 40時間加 熱保持することにより浸炭処理を行った。 これにより、 浸炭処理により 形成される硬化層の厚さは 20〜30 /m程度となる。 The mixed gas of 3 ) (NF 3 concentration 10%) was introduced and heated and maintained at a temperature of 300 to 380 ° C for 20 to 30 minutes. Then, this test piece was placed in a furnace under a mixed gas atmosphere of RX and C0 2, was subjected to carburizing treatment by holding for 40 hours pressurized heat at a temperature 450 to 500 ° C. As a result, the thickness of the hardened layer formed by carburizing becomes about 20 to 30 / m.
No. a— 4， a— 5については、 先ず、 上記と同様に、 試験片に対し てフッ素系ガス雰囲気下で加熱保持する工程を行った。 次に、 この試験 片をアセチレン雰囲気下の炉内に入れて、 この炉内を 1〜30 X 10一2 Torr の真空下にし、 温度 450〜500°Cで 40時間加熱保持するこ とにより浸炭処理を行った。 これにより、 浸炭処理により形成される硬 化層の厚さは 20〜30 zm程度となる。 For Nos. A-4 and a-5, first, a step of heating and holding the test piece in a fluorine-based gas atmosphere was performed in the same manner as above. Next, the test piece was placed in a furnace in an acetylene atmosphere, and the inside of the furnace was evacuated to a vacuum of 1 to 30 × 10 to 12 Torr and heated and maintained at a temperature of 450 to 500 ° C for 40 hours to carburize. Processing was performed. As a result, the thickness of the hardened layer formed by carburizing becomes about 20 to 30 zm.
No. b— l〜b— 3については、 先ず、 上記と同様に、 試験片に対し てフッ素系ガス雰囲気下で加熱保持する工程を行った。 次に、 この試験 片をアンモニアガス雰囲気下の炉内に入れて、 温度 400~450°Cで As for No. bl-1 to b-3, first, a step of heating and holding the test piece in a fluorine-based gas atmosphere was performed in the same manner as described above. Next, the test piece was placed in a furnace under an atmosphere of ammonia gas, and the temperature was 400 to 450 ° C.
48時間加熱保持することにより窒化処理を行った。 これにより、 窒化 処理により形成される硬化層の厚さは 20〜30 m程度となる。 A nitriding treatment was performed by heating and holding for 48 hours. As a result, the thickness of the hardened layer formed by the nitriding treatment becomes about 20 to 30 m.
No. b— 4については、 試験片に対する熱処理を行わずにそのまま用 いた。 No. b— 5, b— 6については、 それぞれ 950°C， 1050 °C に 30分間保持した後に油焼入れし、 160〜 180°Cで 2時間焼き戻 しをしたものを用いた。  For No. b-4, the test piece was used without heat treatment. Nos. B-5 and b-6 were kept at 950 ° C and 1050 ° C for 30 minutes, oil quenched, and tempered at 160-180 ° C for 2 hours.
これらの処理が施された No. a— l〜a— 5 , No. b— l〜b— 6の 試験片について、 表面硬さ、 表面粗さ、 熱処理前後の寸法変化 （膨張量 ) を測定した。 また、 HF— HN03 混合酸に浸漬する酸洗い処理を行 い、 処理後の試験片の状態を調べた。 これらの結果を下記の表 1にまと めて示す。 酸洗い処理の結果は、 外観を観察し、 外観が極めて良好なも のを 「〇」 で、 母材の溶出が生じて外観が著しく損なわれた場合を 「X 」 で示す。 The surface hardness, surface roughness, and dimensional change (expansion amount) before and after heat treatment were measured for the test pieces No. a-l to a-5 and No. b-l to b-6 that were subjected to these treatments. did. Further, HF-HN0 3 have line pickling treatment by immersing in a mixed acid, were examined the state of the test piece after treatment. These results are summarized in Table 1 below. I will show you. The results of the pickling treatment were observed by observing the appearance, and "〇" indicates that the appearance was very good, and "X" indicates that the appearance was significantly impaired due to elution of the base metal.
表 1から分かるように、 浸炭処理によって表面が硬化されている No. a— 1〜a— 5と、 窒化処理によって表面が硬化されている No. b - 1 〜b— 3との比較では、 表面硬さは No. b _ 1〜b— 3の方が硬いが、 表面粗さおよび熱処理前後の寸法変化は No. a— l〜a— 5の方が小さ い。 そのため、 No. a— l〜a— 5の方が後加工性の点で有利である。 また、 酸洗い処理の結果は No. a— 1〜a— 5は全て〇であるが、 No. b—：！〜 b — 3は全て Xであり、 No. a—；！〜 a— 5の方が耐食性およ び製造上の取扱性に優れていることが分かる。  As can be seen from Table 1, a comparison of No. a-1 to a-5, whose surface is hardened by carburizing, and No. b-1 to b-3, whose surface is hardened by nitriding, The surface hardness of No. b_1 to b-3 is harder, but the surface roughness and dimensional change before and after heat treatment are smaller for No. a-1 to a-5. Therefore, No. a-l to a-5 are more advantageous in terms of post-processability. In addition, the results of the pickling treatment are No. a-1 to a-5 for all 〇, but No. b— :! ~ B — 3 are all X, No. a— ;! It can be seen that ~ a-5 is more excellent in corrosion resistance and manufacturing handleability.
熱処理後の試験片の状態については、 No. b _ l〜b— 3では表面に 酸化スケールや窒化物粒子、 煤状堆積物が存在し、 表面が黒くなつてい た。 No. a— l〜a— 3では内部酸化層と表面に煤状堆積物が存在し、 表面が黒くなつていた。 No. a— 4， a _ 5では内部酸化層がほとんど 観察されなかった。  Regarding the condition of the test piece after heat treatment, oxide scale, nitride particles, and soot-like deposits were present on the surface in No. b_l to b-3, and the surface was blackened. In No. a—l to a—3, the inner oxide layer and soot deposits were present on the surface, and the surface was blackened. In Nos. A-4 and a_5, almost no internal oxide layer was observed.
酸洗い処理はこのような内部酸化層や表面堆積物を除去するために行 われるが、 No. b— l〜b— 3はこの酸洗い処理で著しい母材の溶出が 生じることから、 内部酸化層や表面堆積物を完全に除去することができ ない。 これに対して No. a—：！〜 a— 5では、 酸洗い処理で母材の溶出 がほとんど生じないことから、 内部酸化層や表面堆積物を完全に除去す ることができる。  The pickling treatment is performed to remove such internal oxide layers and surface deposits. However, in No. bl-b-3, since the base material is significantly eluted by this pickling treatment, the internal oxidation Layers and surface deposits cannot be completely removed. No. a— :! In ~ a-5, the pickling treatment hardly dissolves the base material, so that the internal oxide layer and surface deposits can be completely removed.
図 2のグラフは、 酸洗い処理前の No. a— 4試験片の表面を X線回折 した結果を示す。 このグラフからは、 母材であるオーステナイ ト系ステ ンレス鋼のピークのみが観察される。 すなわち、 炭素はォ一ステナイ ト の固溶限以下の濃度で、 ォ一ステナイ ト中に完全に固溶している。 図 3 のグラフは、 酸洗い処理前の No. b _ 2試験片の表面を X線回折した結 果を示す。 このグラフからは、 母材であるオーステナイ ト系ステンレス 鋼のピークは全く観察されず、 （C r , F e ) 2 N ( 1 - x , ， C r 2 N等 のクロム窒化物のピークが観察される。 The graph of FIG. 2 shows the result of X-ray diffraction of the surface of No. a-4 test piece before the pickling treatment. From this graph, only the peak of the austenitic stainless steel as the base metal is observed. That is, the carbon is completely dissolved in the monostenite at a concentration lower than the solid solubility limit of the monostenite. Fig. 3 The graph of shows the result of X-ray diffraction of the surface of the No. b_2 test piece before the pickling treatment. From this graph, the peak of the austenitic stainless steel as the base material is not observed at all, (C r, F e) 2 N (1 - x,, the peak of chromium nitride such as C r 2 N is observed Is done.
図 4の写真は、 酸洗い処理前の No. a— 4試験片の表面側の断面を示 す。 図 5の写真は、 酸洗い処理前の No. b _ 2試験片の表面側の断面を 示す。 図 5の写真では、 表面が非常に粗くなつており、 化合物層と母材 との境界が明瞭に分かることに加えて、 クラック等も観察される。 これ に対して図 4の写真では、 表面がなだらかであり、 化合物層と母材との 境界線も認められない。  The photograph in Fig. 4 shows a cross section of the surface of No. a-4 specimen before pickling. The photograph in Fig. 5 shows a cross section on the surface side of the No. b_2 test piece before the pickling treatment. In the photograph of Fig. 5, the surface is very rough, and in addition to clearly seeing the boundary between the compound layer and the base material, cracks and the like are also observed. On the other hand, in the photograph of FIG. 4, the surface is gentle and no boundary between the compound layer and the base material is recognized.
これらの結果から、 No. a— 4試験片の表面側には浸炭処理により析 出物は生成されないが、 No. b— 2試験片の表面側には窒化処理により クロム窒化物からなる化合物層が形成されていることが分かる。  From these results, no deposits were generated on the surface side of No. a-4 test piece by carburizing treatment, but on the surface side of No. b-2 test piece, a compound layer consisting of chromium nitride was formed by nitriding treatment. It can be seen that is formed.
なお、 表 1から分かるように、 マルテンサイ ト系ステンレス鋼からな る No. b— 5， 6は硬度が高い。 これに対して、 No. b— 4は、 溶体化 処理されたォ一ステナイ ト系ステンレス鋼からなるが、 熱処理がされて いないため硬度が低い。 したがって、 No. b— 4の構成では、 加工工程 中の取り扱い時に傷などが生じる恐れがあることが分かる。  As can be seen from Table 1, the hardness of martensite stainless steel No. b-5, 6 is high. On the other hand, No. b-4 is made of solution-treated austenitic stainless steel, but has low hardness because it has not been heat-treated. Therefore, it can be seen that with the configuration of No. b-4, there is a possibility that scratches and the like may occur during handling during the processing process.
次に、 No. a— 1〜 a— 5については上記熱処理と酸洗い処理を行つ た後に、 No. b—：！〜 b— 3の試験片については上記熱処理を施した後 に酸洗い処理を行わないで、 No. b— 4〜b— 6の試験片についてはそ のまま、 研削による仕上げ加工を行った。 この加工後の各試験片につい て、 J I S Z 2 3 7 1に準拠して塩水噴霧試験を 2時間行った。 ま た、 No. b— 7として、 S U S 3 0 3の焼き鈍し品 （固溶化処理なし） を他の試験片と同じ棒状に加工したものを用意し、 これに対して No. a 一 l〜a— 3と同じ熱処理と酸洗い処理を行った後に、 同じ研削による 仕上げ加工を行い、 同じ条件で塩水噴霧試験を行った。 Next, for No. a-1 to a-5, after the above heat treatment and pickling treatment, No. b— :! The test pieces of Nos. B-4 to b-6 were not subjected to the pickling treatment after the heat treatment described above, and the test pieces of Nos. B-4 to b-6 were finished by grinding. Each test piece after the processing was subjected to a salt spray test for 2 hours in accordance with JISZ2371. For No. b-7, an annealed SUS303 (without solution treatment) processed into the same rod shape as the other test pieces was prepared. — After the same heat treatment and pickling treatment as in 3, use the same grinding Finishing was performed and a salt spray test was performed under the same conditions.
その結果を、 下記の表 2に示す。 鯖が全く生じなかった場合を 「〇」 で、 僅かに鲭が生じた場合を 「△」 で、 著しく鎬が生じた場合を 「X」 で示す。  The results are shown in Table 2 below. The case where no mackerel occurred was indicated by “〇”, the case where slight 鲭 occurred was indicated by “△”, and the case where severe ho occurred was indicated by “X”.
表 2から分かるように、 同じ熱処理 （浸炭処理） と酸洗い処理がなさ れた No. a— l〜a— 5， b— 7のうち、 溶体化処理品を使用した No. a— l〜a— 5には、 塩水噴霧試験により鯖が全く生じなかったが、 溶 体化処理品でない焼き鈍し品を使用した No. b— 7には、 僅かに鎬が生 じていた。 また、 窒化処理された No. b— l〜b— 3には、 著しく鑌が 生じた。 熱処理がされていない No. b— 4〜b— 6のうち、 オーステナ イ ト系ステンレス鋼からなる No. b— 4には鯖が生じなかったが、 マル テンサイ ト系ステンレス鋼からなる No. b— 5 , 6には著しく鯖が生じ た。  As can be seen from Table 2, of the heat treated (carburized) and acid pickled Nos. A–l to a–5 and b–7, the no. In a-5, no mackerel was formed by the salt spray test, but in No.b-7, which used an annealed product that was not a solution-treated product, a slight ho appeared. In addition, markedly 鑌 occurred in No. b-l to b-3 after nitriding. Among the unheated No. b-4 to b-6, No. b-4 made of austenitic stainless steel did not produce mackerel, but No. b made of martensitic stainless steel — 5 and 6 had mackerel formation.
図 6のグラフは、 酸洗い処理前の No. b— 7試験片の表面を X線回折 した結果を示す。 このグラフからは、 母材であるオーステナイ ト系ステ ンレス鋼のピーク以外に、 （C r , F e ) a Cやひ一 F e等のピークが 観察される。 この結果から、 オーステナィ ト系ステンレス鋼であっても 溶体化処理品を使用しないと、 浸炭処理時にフェライ 卜と浸炭ガスの反 応が生じて、 （C r， F e ) 3 Cが析出することが分かる。  The graph in Fig. 6 shows the result of X-ray diffraction of the surface of No. b-7 specimen before the pickling treatment. From this graph, in addition to the peak of the austenitic stainless steel as the base metal, peaks such as (Cr, Fe) aC and Hiichi Fe are observed. From this result, even if austenitic stainless steel is not used, the reaction between ferrite and carburizing gas occurs during carburizing, and (Cr, Fe) 3 C precipitates unless a solution-treated product is used. I understand.
以上の結果から、 試験片 No. a— l ~ a— 5に相当する軸と、 銅合金 製のスリーブとを備えた軸受装置は、 使用温度の変化に応じた軸受隙間 の変化がほとんどないばかりでなく、 軸表面の耐食性と十分な硬さが確 保されるため、 装置の信頼性および耐久性が高いものとなることが分か る。 特に、 真空浸炭が施された試験片 No. a— 4 , a— 5と同様にして 得られた軸を備えた軸受装置は、 軸の酸洗い処理工程を省略することが できるため、 作業工程数を少なくできる効果もある。 なお、 上記実施例では、 スリーブを銅合金製としたが、 マルテンサイ ト系ステンレス鋼やフェライ ト系ステンレス鋼からなるスリーブを用い ることにより、 高温時に軸受隙間が僅かに減少するようにして、 高温時 の潤滑剤の粘度低下による軸受剛性の低下を少なくすることもできる。 すなわち、 スリーブに銅合金を用いる代わりに、 スリーブとハブを一体 でフヱライ ト系ステンレス鋼製とし、 軸に溶体化処理されたオーステナ ィ ト系ステンレス鋼を用いて、 高温時の軸受剛性の低下をより一層少な くすることもできる。 From the above results, it can be seen that the bearing device equipped with a shaft corresponding to test piece No. a-l to a-5 and a copper alloy sleeve has almost no change in bearing clearance according to the change in operating temperature. However, it is clear that the corrosion resistance and sufficient hardness of the shaft surface are ensured, so that the equipment has high reliability and durability. In particular, a bearing device equipped with a shaft obtained in the same manner as that of the test pieces No. a-4 and a-5 subjected to vacuum carburization can eliminate the pickling process of the shaft, and therefore the work process There is also an effect that the number can be reduced. In the above embodiment, the sleeve is made of a copper alloy. However, by using a sleeve made of martensite stainless steel or ferrite stainless steel, the bearing gap is slightly reduced at high temperatures, so In this case, it is possible to reduce a decrease in bearing rigidity due to a decrease in viscosity of the lubricant. In other words, instead of using a copper alloy for the sleeve, the sleeve and the hub are made of stainless steel integrally, and the shaft is made of solution-treated austenitic stainless steel to reduce the bearing stiffness at high temperatures. It can be even smaller.
[軸受装置の温度特性試験と起動停止耐久性試験]  [Temperature characteristic test and start / stop durability test of bearing device]
先ず、 図 1の回転装置について、 軸とスリーブとの組合せを下記の表 3に示す組合せとした時の、 0°Cでのトルクと 80°Cでの負荷容量を計 算により求めた。 これらの値は、 軸とスリーブの線膨張係数、 軸径、 軸 受幅、 回転速度、 および潤滑油の粘度を所定の計算式に代入することに よって算出される。  First, the torque at 0 ° C and the load capacity at 80 ° C for the rotating device shown in Fig. 1 when the combinations of shaft and sleeve were the combinations shown in Table 3 below were calculated. These values are calculated by substituting the coefficient of linear expansion of the shaft and the sleeve, the shaft diameter, the bearing width, the rotation speed, and the viscosity of the lubricating oil into predetermined formulas.
軸の直径は 6mmとし、 軸受幅 （両動圧溝 4 1 , 42の軸方向の寸法 ) は 6 mmとした。 潤滑油はジエステル油とし、 回転速度は 7200 r p mとした。  The shaft diameter was 6 mm, and the bearing width (the axial dimension of both hydrodynamic grooves 41 and 42) was 6 mm. The lubricating oil was diester oil and the rotation speed was 7200 rpm.
C 5 19 1 (燐青銅） 、 S US 303、 および S US 304の線膨張 係数は 17〜： L 8 X 10— 6 ( 1/K) であり、 SU S 3 16の線膨張係 数は 1 6〜； 1 7 X 1 0_6 ( 1/K) であり、 SUS 420 J、 SUS 4 40 C、 および SUS 430 F (フェライ ト系ステンレス鋼） の線膨張 係数は 10〜 1 l x l O—6 ( 1/K) であるが、 この計算では以下の数 値を用いた。 C 519 1 (燐青銅） 、 SU S 303、 および SU S 30 4 : 1 7. 3 x 10- 6 ( 1 /K) 。 SUS 3 1 6 : 16. 0 1 0 6 ( 1/K) 。 SUS 420 J、 SUS 440 C、 および SUS 430 F ( フェライ ト系ステンレス鋼） ： 1 0. 3 x 10— 6 ( 1/K) 。 得られた値から、 各サンプル毎に、 0°Cでのトルク値に対する 80°C での負荷容量の比を算出した。 そして、 各比について、 No. 28の比を 1としたときの相対値を、 温度特性値として算出した。 この値が大きい ほど、 軸受装置の温度特性が良好であることを示している。 この結果も 表 3に示す。 C 5 19 1 (phosphor bronze), the linear expansion coefficient of the S US 303, and S US 304. 17 to: a L 8 X 10- 6 (1 / K), SU S 3 16 linear expansion coefficient of 1 6 ~; 17 X 10_ 6 (1 / K), and the linear expansion coefficient of SUS 420 J, SUS 440 C, and SUS 430 F (ferritic stainless steel) is 10 ~ 1 lxl O— 6 ( 1 / K), but the following values were used in this calculation. C 519 1 (phosphor bronze), SU S 303, and SU S 30 4: 1 7. 3 x 10- 6 (1 / K). SUS 3 1 6: 16. 0 1 0 6 (1 / K). SUS 420 J, SUS 440 C, and SUS 430 F (ferritic stainless steel): 1 0. 3 x 10- 6 (1 / K). From the values obtained, the ratio of the load capacity at 80 ° C to the torque value at 0 ° C was calculated for each sample. Then, for each ratio, a relative value when the ratio of No. 28 was set to 1 was calculated as a temperature characteristic value. The larger the value, the better the temperature characteristics of the bearing device. Table 3 also shows the results.
次に、 表 3に示す軸とスリーブとの組合せで、 図 1の回転装置を組み 立てた。 軸の直径は 6 mmであり、 軸受幅 （両動圧溝 4 1， 42の軸方 向の寸法） は 6 mmである。  Next, the rotating device shown in Fig. 1 was assembled by combining the shaft and sleeve shown in Table 3. The shaft diameter is 6 mm, and the bearing width (the axial dimension of both hydrodynamic grooves 41 and 42) is 6 mm.
No. 2 1 , 22, 26の軸は、 前述の a— 3と同じ SUS 303の溶 体化処理品を用い、 a— 3と同じ処理を施して作製した。 No. 23の軸 は、 前述の a— 1と同じ SUS 304の溶体化処理品を用い、 a— 1と 同じ処理を施して作製した。 No. 24， 25の軸は、 前述の a— 5と同 じ SUS 3 16の溶体化処理品を用い、 a— 5と同じ処理を施して作製 した。  The shafts of Nos. 21, 22, and 26 were manufactured by using the same SUS303 solution-processed product as a-3 described above and performing the same treatment as a-3. The shaft of No. 23 was prepared by using the same solution-processed SUS 304 as the above-mentioned a-1 and performing the same processing as a-1. The shafts of Nos. 24 and 25 were manufactured using the same solution-processed SUS316 as in a-5 described above, and subjected to the same processing as a-5.
No. 27の軸は、 前述の b— 4と同じ SUS 303の溶体化処理品を 用い、 b— 4と同様に、 熱処理を行わずにそのまま用いた。 No. 28の 軸は、 前述の b— 5と同じ SUS 420 J 2を用い、 b— 5と同じ処理 を施して作製した。 No. 29の軸は、 前述の b— 6と同じ S US 440 Cを用い、 b— 6と同じ処理を施して作製した。  The shaft of No. 27 used the same solution-processed SUS303 as b-4 described above, and was used without heat treatment as in b-4. The shaft of No. 28 was manufactured by using the same SUS420J2 as b-5 described above and performing the same processing as b-5. The shaft of No. 29 was manufactured using the same SUS440C as in b-6 described above and by performing the same processing as in b-6.
この回転装置を横向きに置き、 潤滑油としてジエステル油を用いて、 ラジアル荷重： 1 N、 回転速度： 7200 r pmの条件で、 この回転装 置を 30万回起動停止させた。 この試験後に、 スリーブの動圧発生溝と 軸の軸受面について、 摩耗による損傷状態を実体顕微鏡を用いて観察し た。 この観察結果も表 3に示す。 表 3において、 「X」 は損傷程度が著 しく大きかったことを、 「〇」 はほとんど損傷が生じていなかつたこと を示す。 表 3に示すように、 No. 2 1 , 23， 24, 26， 2 7では、 軸がォ —ステナイ ト系ステンレス鋼製でスリーブが銅合金製であり、 軸とスリ ーブの熱膨張係数がほぼ同じである。 No. 22と 2 5では、 軸がオース テナイ ト系ステンレス鋼製でスリーブがフェライ ト系ステンレス鋼製で あり、 軸の熱膨張係数よりもスリーブの熱膨張係数が小さい。 No. 2 8 と 29では、 軸がマルテンサイ ト系ステンレス鋼製でスリーブが銅合金 製であり、 軸の熱膨張係数よりもスリーブの熱膨張係数が大きい。 This rotating device was placed sideways, and the rotating device was started and stopped 300,000 times under the conditions of a radial load of 1 N and a rotation speed of 7200 rpm using diester oil as a lubricating oil. After this test, the state of damage caused by wear on the dynamic pressure generating groove of the sleeve and the bearing surface of the shaft was observed using a stereomicroscope. Table 3 also shows the observation results. In Table 3, “X” indicates that the degree of damage was extremely large, and “〇” indicates that almost no damage occurred. As shown in Table 3, in Nos. 21, 23, 24, 26, and 27, the shaft was made of stainless steel and the sleeve was made of a copper alloy. Are almost the same. In Nos. 22 and 25, the shaft is made of austenitic stainless steel and the sleeve is made of ferritic stainless steel, and the thermal expansion coefficient of the sleeve is smaller than that of the shaft. In Nos. 28 and 29, the shaft is made of martensite stainless steel and the sleeve is made of a copper alloy, and the thermal expansion coefficient of the sleeve is larger than that of the shaft.
表 3の結果から分かるように、 温度特性値は、 軸の熱膨張係数よりも スリーブの熱膨張係数が小さい組合せ （No. 2 2， 25) で最も大きく 、 軸とスリーブの熱膨張係数がほぼ同じ組合せ （No. 2 1 , 23 , 24 ， 2 6， 2 7) 、 軸の熱膨張係数よりもスリーブの熱膨張係数が大きい 組合せ （No. 2 8 , 29 ) の順に小さくなる。  As can be seen from the results in Table 3, the temperature characteristic value is largest in the combination (No. 22, 25) where the thermal expansion coefficient of the sleeve is smaller than the thermal expansion coefficient of the shaft, and the thermal expansion coefficient of the shaft and the sleeve is almost the same. The same combination (Nos. 21, 23, 24, 26, 27) and the combination (No. 28, 29) with the sleeve's thermal expansion coefficient larger than the shaft's thermal expansion coefficient become smaller.
すなわち、 高温時には、 潤滑油の粘度低下に伴う軸受剛性の低下が生 じるが、 軸の熱膨張係数よりもスリーブの熱膨張係数が小さい組合せ （ No. 22, 25) では、 温度上昇に伴って軸受隙間が小さくなるため、 高温時の軸受剛性を改善することができる。 これに対して、 軸の熱膨張 係数よりもスリーブの熱膨張係数が大きい組合せ （No. 28と 29) で は、 温度上昇に伴って軸受隙間が大きくなるため、 高温時に軸受剛性が 大きく低下する。  In other words, at high temperatures, the bearing stiffness decreases due to the decrease in the viscosity of the lubricating oil, but in combinations (No. 22, 25) where the thermal expansion coefficient of the sleeve is smaller than that of the shaft, the temperature rises. As a result, the bearing gap is reduced, so that the bearing stiffness at high temperatures can be improved. On the other hand, in combinations (No. 28 and 29) where the thermal expansion coefficient of the sleeve is larger than the thermal expansion coefficient of the shaft, the bearing stiffness decreases significantly at high temperatures because the bearing gap increases with increasing temperature. .
起動停止耐久性については、 軸の表面硬さが Hv 400以上であり、 且つ表面粗さ （R a) が 0. 30 /m以下である No. 2 1〜25 , 2 8 , 29で良好な結果が得られた。 これに対して、 軸の表面硬さが Hv 2 00未満と極めて低い No. 2 7と、 表面粗さ （R a) が 0. 30〃mを 超えた値である No. 2 6では、 起動停止耐久性が不十分であった。 表 2 Regarding the start / stop durability, No. 2 1 to 25, 28 and 29 with shaft surface hardness of Hv 400 or more and surface roughness (Ra) of 0.30 / m or less are good. The result was obtained. In contrast, No. 27, whose shaft surface hardness is extremely low, less than Hv200, and No. 26, whose surface roughness (R a) exceeds 0.30 m, start up Stopping durability was insufficient. Table 2
Figure imgf000018_0002
Figure imgf000018_0002
Figure imgf000018_0003
3
Figure imgf000018_0003
Three
Figure imgf000018_0001
産業上の利用可能性
Figure imgf000018_0001
Industrial applicability
以上説明したように、 本発明の軸受装置によれば、 軸を銅合金と熱膨 張係数がほぼ等しいオーステナイ ト系ステンレス鋼製としながら、 軸表 面の耐食性と十分な硬さが確保される。  As described above, according to the bearing device of the present invention, corrosion resistance and sufficient hardness of the shaft surface are ensured while the shaft is made of austenitic stainless steel having a thermal expansion coefficient substantially equal to that of a copper alloy. .
また、 本発明によれば、 軸の表面硬度が高く、 且つ軸の軸受面の粗さ が良好であることによって、 軸受の起動停止耐久性に優れているととも に、 軸の耐食性にも優れた軸受装置が得られる。  Further, according to the present invention, the shaft has a high surface hardness and a good roughness of the bearing surface of the shaft, so that the bearing has excellent durability in starting and stopping and also has excellent corrosion resistance in the shaft. Bearing device is obtained.
また、 本発明の軸受装置によれば、 銅合金からなるスリーブと組み合 わせる軸の材料および表面硬化方法を特定することによって、 使用温度 の変化に応じた軸受隙間の変化がほとんどないばかりでなく、 軸表面の 耐食性と十分な硬さが確保されるため、 装置の信頼性および耐久性が高 いものとなる。  Further, according to the bearing device of the present invention, by specifying the material of the shaft to be combined with the sleeve made of the copper alloy and the surface hardening method, the bearing gap hardly changes according to the change in the operating temperature. As a result, the corrosion resistance and sufficient hardness of the shaft surface are ensured, so that the reliability and durability of the equipment are high.
また、 本発明の軸受装置によれば、 軸の熱膨張係数よりもスリーブの 熱膨張係数が小さい組合せとすることによって、 高温時の軸受剛性を改 善することができる。  Further, according to the bearing device of the present invention, the rigidity of the bearing at high temperatures can be improved by using a combination in which the thermal expansion coefficient of the sleeve is smaller than the thermal expansion coefficient of the shaft.

Claims

請 求 の 範 囲 The scope of the claims
1. 軸とスリーブとを備え、 両者の間に動圧を生じさせて軸受作用を得 る軸受装置において、 1. In a bearing device that has a shaft and a sleeve and generates a dynamic pressure between them to obtain a bearing action,
前記軸は、 溶体化処理されたオーステナイ ト系ステンレス鋼からなる 軸状体に浸炭処理を施すことにより表面に浸炭硬化層が形成されたもの であり、 この軸の軸受面の表面硬さは Hv 400以上であることを特徴 とする軸受装置。  The shaft has a carburized hardened layer formed on its surface by subjecting a shaft made of solution-treated austenitic stainless steel to a carburizing treatment, and the bearing surface of the shaft has a surface hardness of Hv A bearing device characterized by being 400 or more.
2. 前記軸の軸受面の表面粗さ （Ra) は 0. 30〃m以下である請求 項 1記載の軸受装置。  2. The bearing device according to claim 1, wherein a surface roughness (Ra) of a bearing surface of the shaft is 0.30 m or less.
3. 前記スリーブをなす材料の熱膨張係数は、 軸をなすオーステナィ ト 系ステンレス鋼の熱膨張係数と同じまたはほぼ同じである請求項 1又は 2記載の軸受装置。  3. The bearing device according to claim 1, wherein a thermal expansion coefficient of the material forming the sleeve is the same as or approximately the same as a thermal expansion coefficient of the austenitic stainless steel forming the shaft.
4. 前記スリーブは銅合金からなる請求項 3記載の軸受装置。  4. The bearing device according to claim 3, wherein the sleeve is made of a copper alloy.
5. 前記スリーブは、 軸をなすオーステナイ ト系ステンレス鋼よりも熱 膨張係数が小さい材料からなる請求項 1又は 2記載の軸受装置。 5. The bearing device according to claim 1, wherein the sleeve is made of a material having a smaller coefficient of thermal expansion than the austenitic stainless steel forming the shaft.
6. 前記スリーブはフェライ ト系ステンレス鋼またはマルテンサイ ト系 ステンレス鋼からなる請求項 5記載の軸受装置。  6. The bearing device according to claim 5, wherein the sleeve is made of ferrite stainless steel or martensite stainless steel.
7. 請求項 1〜 6のいずれか 1項に記載された軸受装置の製造方法であ つて、  7. A method for manufacturing a bearing device according to any one of claims 1 to 6, wherein
前記浸炭処理は、 浸炭ガス雰囲気下で温度 400〜500°Cで行い、 少なくとも軸の軸受面に浸炭硬化層を設けることを特徴とする軸受装置 の製造方法。  The method for producing a bearing device, wherein the carburizing treatment is performed in a carburizing gas atmosphere at a temperature of 400 to 500 ° C., and a carburized hardened layer is provided on at least a bearing surface of the shaft.
8. 前記浸炭処理は、 RXガスと C02 ガスとの混合ガスの雰囲気下で 行う請求項 7記載の製造方法。 8. The carburizing method according to claim 7, wherein performing in an atmosphere of a gas mixture of RX gas and C0 2 gas.
9. 前記浸炭処理は、 真空下で不飽和炭化水素ガスの雰囲気下で行う請 求項 7記載の製造方法。 9. The above carburizing treatment must be performed in an atmosphere of unsaturated hydrocarbon gas under vacuum. The production method according to claim 7, wherein:
1 0. 前記浸炭処理の前に、 フッ素系ガス雰囲気下で温度 250〜45 0°Cに加熱保持する工程を行う請求項 7〜 9のいずれか 1項に記載の製 造方法。  10. The production method according to any one of claims 7 to 9, wherein a step of heating and holding at a temperature of 250 to 450 ° C in a fluorine-based gas atmosphere is performed before the carburizing treatment.
PCT/JP2000/003614 1999-06-04 2000-06-02 Bearing device and method of manufacturing the bearing device WO2000075522A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP15814899 1999-06-04
JP11/158148 1999-06-04

Publications (1)

Publication Number Publication Date
WO2000075522A1 true WO2000075522A1 (en) 2000-12-14

Family

ID=15665318

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/JP2000/003614 WO2000075522A1 (en) 1999-06-04 2000-06-02 Bearing device and method of manufacturing the bearing device

Country Status (1)

Country Link
WO (1) WO2000075522A1 (en)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2004010014A1 (en) * 2002-07-18 2004-01-29 Yoshinari Yokoo Dynamic pressure bearing device, spindle motor, disk drive device, and method of manufacturing dynamic pressure bearing device
JP2004068154A (en) * 2002-08-01 2004-03-04 Ipsen Internatl Gmbh Method and device for blackening member
JP2006329262A (en) * 2005-05-24 2006-12-07 Nippon Densan Corp Dynamic pressure bearing device and motor equipped with the device, and disk device using the motor
JP2007046088A (en) * 2005-08-09 2007-02-22 Yuki Koshuha:Kk Nitrided quenched part, and method for producing the same
WO2006109039A3 (en) * 2005-04-15 2007-05-03 Gsi Group Ltd Gas bearing spindle
JP2008544085A (en) * 2005-06-22 2008-12-04 ダンマークス テクニスケ ウニヴァシティット ディ・ティ・ウ Carburizing method in hydrocarbon gas
JP2011190513A (en) * 2010-03-16 2011-09-29 Tnk Sanwa Precision Co Ltd Method for manufacturing sliding component

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS62125351U (en) * 1986-01-31 1987-08-08
JPH09249959A (en) * 1996-01-09 1997-09-22 Daido Hoxan Inc Method for carburizing treatment to austenitic metal and austenitic metal product obtained thereby
JPH09302456A (en) * 1996-03-14 1997-11-25 Daido Hoxan Inc High corrosion resistant metallic product and its production
JPH1089345A (en) * 1996-09-10 1998-04-07 Koyo Seiko Co Ltd Dynamic pressure bearing
JPH10330906A (en) * 1997-06-05 1998-12-15 Daido Hoxan Inc Production of austenitic stainless steel product
JP2000161346A (en) * 1998-11-27 2000-06-13 Nsk Ltd Spindle motor

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS62125351U (en) * 1986-01-31 1987-08-08
JPH09249959A (en) * 1996-01-09 1997-09-22 Daido Hoxan Inc Method for carburizing treatment to austenitic metal and austenitic metal product obtained thereby
JPH09302456A (en) * 1996-03-14 1997-11-25 Daido Hoxan Inc High corrosion resistant metallic product and its production
JPH1089345A (en) * 1996-09-10 1998-04-07 Koyo Seiko Co Ltd Dynamic pressure bearing
JPH10330906A (en) * 1997-06-05 1998-12-15 Daido Hoxan Inc Production of austenitic stainless steel product
JP2000161346A (en) * 1998-11-27 2000-06-13 Nsk Ltd Spindle motor

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2004010014A1 (en) * 2002-07-18 2004-01-29 Yoshinari Yokoo Dynamic pressure bearing device, spindle motor, disk drive device, and method of manufacturing dynamic pressure bearing device
US7134791B2 (en) 2002-07-18 2006-11-14 Yoshinari Yokoo Dynamic pressure bearing device, spindle motor, disk drive device, and method of manufacturing dynamic pressure bearing device
JP2004068154A (en) * 2002-08-01 2004-03-04 Ipsen Internatl Gmbh Method and device for blackening member
WO2006109039A3 (en) * 2005-04-15 2007-05-03 Gsi Group Ltd Gas bearing spindle
GB2440299A (en) * 2005-04-15 2008-01-23 Gsi Group Ltd Gas bearing spindle
GB2440299B (en) * 2005-04-15 2008-10-01 Gsi Group Ltd Gas bearing spindle
JP2006329262A (en) * 2005-05-24 2006-12-07 Nippon Densan Corp Dynamic pressure bearing device and motor equipped with the device, and disk device using the motor
JP2008544085A (en) * 2005-06-22 2008-12-04 ダンマークス テクニスケ ウニヴァシティット ディ・ティ・ウ Carburizing method in hydrocarbon gas
JP2007046088A (en) * 2005-08-09 2007-02-22 Yuki Koshuha:Kk Nitrided quenched part, and method for producing the same
JP2011190513A (en) * 2010-03-16 2011-09-29 Tnk Sanwa Precision Co Ltd Method for manufacturing sliding component

Similar Documents

Publication Publication Date Title
JP3588935B2 (en) Rolling bearings and other rolling devices
US7122086B2 (en) Rolling support device and method for manufacturing the same
CN102037159B (en) Iron and steel material having quenched surface layer part, process for producing the iron and steel material, and quenched component
US20080277031A1 (en) Surface-carbonitrided stainless steel part excellent in wear resistance and its manufacturing method
WO2008023410A1 (en) Austenite-base stainless steel pipe, for boiler, having excellent high-temperature steam oxidation resistance
JP4442030B2 (en) Method for manufacturing rolling support device
JP2002115030A (en) Rolling bearing for spindle of machine tool
US6071358A (en) Rolling member and rolling device comprising the same
US20020064326A1 (en) Rolling bearing device
WO2000075522A1 (en) Bearing device and method of manufacturing the bearing device
JPH11303874A (en) Rolling member
JP2005030569A (en) Cam follower
JP4921149B2 (en) Metal nitriding method
JP3003831B2 (en) Oil-tempered wire and method for producing the same
JP2004003627A (en) Shaft, planetary gear device and cam follower
EP1420078A2 (en) Brearing steel excellent in corrosion resistance
JP7264117B2 (en) Steel part and its manufacturing method
JP2005232543A (en) Ball screw
JP2001227550A (en) Rolling member
JP2000199524A (en) Rolling device
KR930009989B1 (en) Method for treating the surface of a rotational shaft used in fluid compressing apparatus
CN117551967A (en) Method for improving wear resistance of titanium alloy part
JP7178832B2 (en) Method for manufacturing surface hardening material
JP4327812B2 (en) Manufacturing method of carburized parts
JP2022157220A (en) Case hardening steel and carburized component

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): JP US

WWE Wipo information: entry into national phase

Ref document number: 09720778

Country of ref document: US

ENP Entry into the national phase

Ref country code: JP

Ref document number: 2001 501769

Kind code of ref document: A

Format of ref document f/p: F