US20120210765A1 - Method for Manufacturing Mechanical Part Excellent in Rolling Fatigue Life - Google Patents
Method for Manufacturing Mechanical Part Excellent in Rolling Fatigue Life Download PDFInfo
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- US20120210765A1 US20120210765A1 US13/390,793 US201013390793A US2012210765A1 US 20120210765 A1 US20120210765 A1 US 20120210765A1 US 201013390793 A US201013390793 A US 201013390793A US 2012210765 A1 US2012210765 A1 US 2012210765A1
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- rolling
- steel
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
- F16C33/00—Parts of bearings; Special methods for making bearings or parts thereof
- F16C33/30—Parts of ball or roller bearings
- F16C33/58—Raceways; Race rings
- F16C33/64—Special methods of manufacture
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21J—FORGING; HAMMERING; PRESSING METAL; RIVETING; FORGE FURNACES
- B21J5/00—Methods for forging, hammering, or pressing; Special equipment or accessories therefor
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21J—FORGING; HAMMERING; PRESSING METAL; RIVETING; FORGE FURNACES
- B21J5/00—Methods for forging, hammering, or pressing; Special equipment or accessories therefor
- B21J5/06—Methods for forging, hammering, or pressing; Special equipment or accessories therefor for performing particular operations
- B21J5/08—Upsetting
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21K—MAKING FORGED OR PRESSED METAL PRODUCTS, e.g. HORSE-SHOES, RIVETS, BOLTS OR WHEELS
- B21K1/00—Making machine elements
- B21K1/04—Making machine elements ball-races or sliding bearing races
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21K—MAKING FORGED OR PRESSED METAL PRODUCTS, e.g. HORSE-SHOES, RIVETS, BOLTS OR WHEELS
- B21K21/00—Making hollow articles not covered by a single preceding sub-group
- B21K21/16—Remodelling hollow bodies with respect to the shape of the cross-section
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21K—MAKING FORGED OR PRESSED METAL PRODUCTS, e.g. HORSE-SHOES, RIVETS, BOLTS OR WHEELS
- B21K23/00—Making other articles
- B21K23/04—Making other articles flanged articles
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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
- C21D1/18—Hardening; Quenching with or without subsequent tempering
- C21D1/25—Hardening, combined with annealing between 300 degrees Celsius and 600 degrees Celsius, i.e. heat refining ("Vergüten")
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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
- C21D1/26—Methods of annealing
- C21D1/32—Soft annealing, e.g. spheroidising
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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
- C21D7/00—Modifying the physical properties of iron or steel by deformation
- C21D7/02—Modifying the physical properties of iron or steel by deformation by cold working
- C21D7/10—Modifying the physical properties of iron or steel by deformation by cold working of the whole cross-section, e.g. of concrete reinforcing bars
-
- 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
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/10—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of tubular bodies
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/40—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for rings; for bearing races
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- 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
- F16C19/14—Bearings with rolling contact, for exclusively rotary movement with bearing balls essentially of the same size in one or more circular rows for both radial and axial load
- F16C19/18—Bearings with rolling contact, for exclusively rotary movement with bearing balls essentially of the same size in one or more circular rows for both radial and axial load with two or more rows of balls
- F16C19/181—Bearings with rolling contact, for exclusively rotary movement with bearing balls essentially of the same size in one or more circular rows for both radial and axial load with two or more rows of balls with angular contact
- F16C19/183—Bearings with rolling contact, for exclusively rotary movement with bearing balls essentially of the same size in one or more circular rows for both radial and axial load with two or more rows of balls with angular contact with two rows at opposite angles
- F16C19/184—Bearings with rolling contact, for exclusively rotary movement with bearing balls essentially of the same size in one or more circular rows for both radial and axial load with two or more rows of balls with angular contact with two rows at opposite angles in O-arrangement
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
- F16C2240/00—Specified values or numerical ranges of parameters; Relations between them
- F16C2240/40—Linear dimensions, e.g. length, radius, thickness, gap
Definitions
- the present invention relates to production of a mechanical part made of a steel material, such as a bearing, a gear, a hub unit, a variable speed transmission, a constant velocity joint or a piston pin, particularly to production of a mechanical part comprising an annular body for which a good rolling fatigue life is required.
- Non-Patent Literature 1 and Non-Patent Literature 2 the process leading to a rolling fatigue failure, namely flaking, is explained as follows. That is, in the process that cracks originated from the non-metallic inclusion lead to the generation of flaking through their growth, there is involved a crack initiation stage (hereinafter, “Mode I-type initial crack”) in which the crack is displaced due to a stress concentration effect onto the periphery of the non-metallic inclusion. It is known that this then leads to failure through propagation of the crack by shear stress. This means that if a Mode I-type initial crack is not generated, subsequent crack propagation or failure does not occur. In addition, the Mode I-type initial crack occurs on the premise that there is generated a physical cavity, in an interface between the non-metallic inclusion and the matrix. It is also verified that unless the physical cavity is generated, the Mode I-type crack is not generated.
- FIG. 5 is a conceptual diagram showing an image of the periphery of the non-metallic inclusion in a test piece which was cut out from a hot rolled steel material and then subjected to ion milling, when observed by a scanning electron microscope (FE-SEM) to confirm presence/absence of cavities therein.
- FE-SEM scanning electron microscope
- code 5 indicates a non-metallic inclusion of Al 2 O 3
- code 4 indicates cavities. Particularly in machine structural steel, deoxidation by Al is normally performed. An Al 2 O 3 -based non-metallic inclusion 5 formed at this time is confirmed to tend to easily generate cavities 4 particularly in an interface with the matrix due to the difference in deformability from the matrix or due to the shape. Therefore, in order to improve the rolling fatigue life of the mechanical part 7 , it is effective to close the cavity 4 existing in the interface between the non-metallic inclusion 5 and the matrix or to reduce the volume of the cavity 4 .
- the present invention is directed to a technology relating to (3) described in the above paragraph [0006] and is to provide a method for producing a mechanical part having a rolling portion superior in rolling fatigue life on the inner diameter surface of an annular workpiece material, by conducting plastic processing to improve the state of the interface between non-metallic inclusions and the matrix steel material contained in the steel material constituting the annular workpiece material, which is to be subjected to cold forging, as compared to the conventional method for producing the conventional steel material aiming at reducing the non-metallic inclusions and reducing the diameters of the non-metallic inclusions.
- a method for producing a mechanical part superior in rolling fatigue life wherein the mechanical part comprises a rolling portion for a rolling element to roll along an inner diameter surface of an annular workpiece material subjected to cold forging, wherein the method comprises the step of performing cold forging by applying a hydrostatic stress to the inner diameter surface of the annular workpiece material on which the rolling portion is to be formed, thereby forming the rolling portion on the inner diameter surface of the annular workpiece material for the rolling element to roll therealong and increasing an inner diameter of the annular workpiece material other than the rolling portion, so as to provide an annular mechanical part comprising the rolling portion superior in rolling fatigue life.
- the application of this hydrostatic pressure directs the cavities existing in the interface between non-metallic inclusions in the steel and the steel matrix to close, enabling production of a mechanical part superior in rolling fatigue life.
- the annular workpiece material to be subjected to cold forging is preferably a steel pipe or a hot forged ring.
- the hydrostatic stress is at least 1000 MPa.
- Applying a hydrostatic stress of at least 1000 MPa during cold forging to form a rolling surface makes it possible to close the cavities existing in the interface between the non-metallic inclusions contained in the steel and the steel matrix and thus to produce a mechanical part superior in rolling fatigue life.
- the cavities generated in the interface between the non-metallic inclusions and the steel matrix can be closed or reduced even without reducing the amount of the non-metallic inclusions and without reducing the diameters thereof at the time of producing the steel material.
- a hydrostatic stress preferably at least 1000 MPa
- FIG. 1A is a schematic view explaining a cold forging process (before compression processing) for an annular matrix according to the present invention.
- FIG. 1B is a schematic view explaining a cold forging process (after compression processing) for the annular matrix according to the present invention.
- FIG. 2 is a longitudinal cross-sectional view of a rolling bearing produced in accordance with the method of the present invention.
- FIG. 3 is a diagram showing CAE analysis of the rolling bearing produced in accordance with the method of the present invention
- FIG. 4A is a conceptual diagram showing a non-metallic inclusion and cavities in the periphery thereof before cold forging.
- FIG. 4B is a conceptual diagram showing a non-metallic inclusion and cavities in the periphery thereof after cold forging.
- FIG. 5 is a conceptual diagram showing a non-metallic inclusion of a hot rolled steel material and cavities in the periphery thereof.
- the steel material required for the production method of the present invention may be machine structural steel and bearing steel.
- These machine structural steels are generally produced as a steel material through 1) oxidation refining of molten steel in an arc melting furnace or a converter furnace, 2) reduction refining in a ladle refining furnace (LF), 3) rotary-flow vacuum degassing treatment by a rotary-flow vacuum degasser (RH treatment), 4) casting of steel ingot by continuous casting or ingot casting and 5) plastic working of steel ingot by hot rolling or hot forging and cold rolling or by cold rolling and cold forging.
- LF ladle refining furnace
- RH treatment rotary-flow vacuum degasser
- the annular matrix 2 used in the production method of the present invention can be produced as follows. First of all, the steel material produced as described above (for example, steel materials defined in JIS G 4805 (2008), JIS G 4051 (2005), JIS G 4104 or JIS G 4105) is subjected to the process of the aforementioned plastic working to produce a steel material. This steel material is subjected to asset milling, extrusion processing or hot processing such as hot forging to be processed into a steel pipe or a hot forged ring, which is then cut to a predetermined length. Further, the outer diameter surface and the inner diameter surface of the cut steel pipe or hot forged ring are subjected to cutting processing, and thus provide a steel pipe or hot forged ring provided with predetermined dimensions as the annular matrix 2 .
- the steel material produced as described above for example, steel materials defined in JIS G 4805 (2008), JIS G 4051 (2005), JIS G 4104 or JIS G 4105
- This steel material is subjected to asset milling, extru
- the process according to the present invention will be explained with reference to FIG. 1 .
- the annular matrix 2 in a predetermined configuration is subjected to appropriate lubrication processing to have a temperature around room temperature.
- the annular matrix 2 is set within an annular retraining frame 1 in a press apparatus as shown in FIG. 1A .
- Dies 3 are arranged at upper and lower positions in the restraining frame 1 and are respectively fixed to moving parts (not shown) at upper and lower positions in the press apparatus.
- an upper punch 3 a of the fixed die 3 and an annular upper punch 3 b arranged around the upper punch 3 a start a descending motion in the arrow direction.
- the descending upper punch 3 a and annular upper punch 3 b applies plastic working to the inner diameter 2 a and the upper end face 2 b of the annular matrix 2 .
- the annular matrix 2 is pushed downward, while at the same time a lower punch 3 c and an annular lower punch 3 d of the die 3 applies plastic working to the inner diameter 2 a and the lower end face 2 c of the annular matrix 2 . That is, the upper end face 2 b of the annular matrix 2 is pushed downward following the descending of the upper punch 3 a and the annular upper punch 3 b.
- the lower end face 2 c of the annular matrix 2 is relatively pushed up by the lower punch 3 c and the annular lower punch 3 d.
- the annular matrix 2 is subjected to compression processing to receive a hydrostatic stress by cold forging from the upper punch 3 a and the annular upper punch 3 b as well as the lower punch 3 c and the annular lower punch 3 d, thereby closing the cavities 4 existing between the steel matrix of the annular matrix 2 and the non-metallic inclusions 5 .
- Test pieces (unit: % by mass) Steel Type C Si Mn P S Cu Ni Mo Cr Al SUJ2 1.04 0.22 0.32 0.008 0.007 — — 0.03 1.44 0.011 SUJ3 1.00 0.55 1.01 0.007 0.008 0.03 0.05 0.01 0.99 — S45C 0.44 0.20 0.70 0.01 0.01 — — — — — S53C 0.52 0.20 0.65 0.01 0.01 — — — — — —
- This example was implemented on test pieces of steel types shown in Table 1.
- molten steel was subjected to an oxidation refining in an arc melting furnace, a reduction refining in a ladle refining furnace (LF), and a degassing processing in a rotary-flow vacuum degasser (RH) for reducing the oxygen content in the molten steel, which was then subjected to continuous casting to produce a steel ingot.
- the steel ingot was subjected to conventional hot rolling to provide a steel material, which was then processed to form a steel pipe by assel mill.
- the steel pipe was then subjected to conventional spheroidized annealing to prepare a steel pipe.
- the above-obtained steel pipe made of the test piece shown in Table 1 and having an outer diameter ⁇ of 80 mm and a thickness of 8.7 mm was sawn to a steel pipe having a width of 27.2 mm in the longitudinal direction of the steel pipe, of which the outer diameter and the inner diameter were subjected to cutting processing to provide a steel pipe having an outer diameter ⁇ of 78.5 mm and a thickness of 7.0 mm.
- This steel pipe was then subjected to conventional lubrication processing to provide an annual matrix 2 for cold forging.
- the annular matrix 2 was subjected to the following cold forging, as shown in FIG.
- the cold forging applies a hydrostatic stress of up to approximately 1500 MPa to the vicinity of the rolling portion 6 , as predicted from the CAE analysis diagram shown in FIG. 3 .
- FIG. 4A and FIG. 4B schematically show the change of the cavities 4 existing between the non-metallic inclusion 5 and the steel as the annular matrix 2 from before to after the cold forging.
- FIG. 4A shows a configuration of the non-metallic inclusion 5 in the annular matrix 2 before the cold forging, with the cavities 4 being formed adjacent to the non-metallic inclusion 5 .
- FIG. 4B shows that it was confirmed that the cavity 4 existing between the non-metallic inclusion 5 and the steel as the annular matrix 2 was closed after the cold forging.
- test pieces were subjected to turning processing to form a bearing washer which is a member of a thrust rolling bearing, followed by quenching and tempering treatment. There were thus obtained a hardness of HRB 94 or more for S45C, a hardness of HRC 20 or more for S53C, and a hardness of HRC 58 or more for SUJ2 and SUJ3.
- the test pieces were further subjected to grinding to provide a thrust rolling bearing, followed by evaluation of the rolling fatigue life thereof.
- a commercially available ball for the thrust rolling bearing was used for the rolling body.
- the evaluation results of the rolling fatigue life were shown in Table 3 in accordance with three-step criteria including A: excellent, B: good, and C: poor.
- the number before hyphen “-” in the conditions in Table 3 refers to steel type condition in Table 2 while the alphabetical letter after hyphen “-” refers to processing condition in Table 2. Since the hardness is different from each other among steel types, the same evaluation cannot be made thereamong. Therefore, the evaluation of the rolling fatigue life was made based upon comparison among the same steel types.
- Test pieces are produced in the same way as in Example 1, except that hot forged rings are produced instead of the steel pipes.
- the method for producing the hot forged ring is as follows. First of all, molten steel was subjected to an oxidation refining in an arc melting furnace, a reduction refining in a ladle refining furnace (LF), and a degassing processing in a rotary-flow vacuum degasser (RH) for reducing the oxygen content in the molten steel, which was then subjected to continuous casting to produce a steel ingot.
- the steel ingot was subjected to conventional hot rolling to provide a steel material, which was then processed to form a billet by shear cutting.
- the billet was then subjected to hot forging to provide a hot forged ring having an outer diameter ⁇ of 80 mm, a thickness of 8.7 mm and a width of 27.2 mm.
- the hot forged ring was subjected to conventional spheroidized annealing to prepare a hot forged ring.
- the outer diameter and the inner diameter of the hot forged ring made of the above-obtained test piece shown in Table 1 were subjected to cutting processing to provide a hot forged ring having an outer diameter ⁇ of 78.5 mm and a thickness of 7.0 mm.
- the hot forged ring was then subjected to conventional lubrication processing to form an annual matrix 2 for cold forging. Cold forging and its subsequent processes using the annular matrix 2 are the same as in Example 1. In this case, effects similar to those attained in Example 1 can also be attained.
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Abstract
Disclosed is a method for producing a mechanical part superior in rolling fatigue life. The mechanical part includes a rolling portion for a rolling element to roll along an inner diameter surface of an annular workpiece material subjected to cold forging. The method includes performing cold forging by applying a hydrostatic stress to the inner diameter surface of the annular workpiece material on which the rolling portion is to be formed, thereby forming the rolling portion on the inner diameter surface of the annular workpiece material for the rolling element to roll therealong and increasing an inner diameter of the annular workpiece material other than the rolling portion, so as to provide an annular mechanical part including the rolling portion superior in rolling fatigue life.
Description
- This application claims priority to Japanese Patent Application No. 2009-194962 filed on Aug. 26, 2009 and Japanese Patent Application No. 2010-185927 filed on Aug. 23, 2010, the entire disclosures of which are incorporated herein by reference.
- The present invention relates to production of a mechanical part made of a steel material, such as a bearing, a gear, a hub unit, a variable speed transmission, a constant velocity joint or a piston pin, particularly to production of a mechanical part comprising an annular body for which a good rolling fatigue life is required.
- In recent years, with increasingly high performance in various mechanical apparatuses, usage environments of mechanical parts or apparatuses for which a rolling fatigue life is required become very severe, causing a strong demand for improvements in operating life and reliability of these mechanical parts or apparatuses. In response to such a demand, as a measure in terms of steel materials, there has been conducted proper adjustment of steel ingredients or reduction of impurity elements contained along with the steel ingredients.
- Among the impurity elements contained along with the steel ingredients constituting these mechanical parts or apparatuses, Al2O3, MnS, TiN and other non-metallic inclusions consisting of these impurity elements may originate a failure in steel parts of the mechanical parts or apparatuses. For this reason, it is known that these non-metallic inclusions are particularly detrimental. It is further known that a larger diameter of the non-metallic inclusion leads to a shorter rolling fatigue life of steel parts. Thus, there has been proposed various high cleanliness steel having a reduced amount of non-metallic inclusions, with the purification level of the steel being heightened and with an extremely reduced amount of large oxide-based non-metallic inclusions having diameters of 20 μm or more (for example, see
Patent Literature 1 and Patent Literature 2). - In the meantime, even if a steel material made of such high cleanliness steel is used for a mechanical part or apparatus, it has not yet been sufficiently achieved to prevent the mechanical part or apparatus from leading to failure in a short life span. For this reason, developments are being actively conducted to reduce the amount of non-metallic inclusions in the steel material and further to reduce the diameters of the non-metallic inclusions.
- On the other hand, technological developments are also being actively conducted to provide mechanical parts excellent in rolling fatigue life even without reducing the amount of the non-metallic inclusions in the steel material and without reducing the diameters thereof. For example, there has been proposed: (1) a technique in which, at the time of producing a part by rolling motion, a fiber flow on a rolling portion is controlled to obtain an excellent rolling fatigue life (for example, see Patent Literature 3) and (2) a technique in which a compression stress is applied in advance to a rolling portion to obtain an excellent rolling fatigue life (for example, see Patent Literature 4). In addition, the applicant has proposed (3) a technique of providing a steel material with an improved interface state between non-metallic inclusions contained in the steel material and the matrix steel to achieve an excellent rolling fatigue life. These techniques are published in Non-Patent
Literature 1 and Non-Patent Literature 2. - In
Non-Patent Literature 1 andNon-Patent Literature 2, the process leading to a rolling fatigue failure, namely flaking, is explained as follows. That is, in the process that cracks originated from the non-metallic inclusion lead to the generation of flaking through their growth, there is involved a crack initiation stage (hereinafter, “Mode I-type initial crack”) in which the crack is displaced due to a stress concentration effect onto the periphery of the non-metallic inclusion. It is known that this then leads to failure through propagation of the crack by shear stress. This means that if a Mode I-type initial crack is not generated, subsequent crack propagation or failure does not occur. In addition, the Mode I-type initial crack occurs on the premise that there is generated a physical cavity, in an interface between the non-metallic inclusion and the matrix. It is also verified that unless the physical cavity is generated, the Mode I-type crack is not generated. - Meanwhile,
FIG. 5 is a conceptual diagram showing an image of the periphery of the non-metallic inclusion in a test piece which was cut out from a hot rolled steel material and then subjected to ion milling, when observed by a scanning electron microscope (FE-SEM) to confirm presence/absence of cavities therein. In -
FIG. 5 ,code 5 indicates a non-metallic inclusion of Al2O3, whilecode 4 indicates cavities. Particularly in machine structural steel, deoxidation by Al is normally performed. An Al2O3-basednon-metallic inclusion 5 formed at this time is confirmed to tend to easily generatecavities 4 particularly in an interface with the matrix due to the difference in deformability from the matrix or due to the shape. Therefore, in order to improve the rolling fatigue life of themechanical part 7, it is effective to close thecavity 4 existing in the interface between thenon-metallic inclusion 5 and the matrix or to reduce the volume of thecavity 4. -
- Patent Literature 1: JP2006-63402A
- Patent Literature 2: JP06-192790A
- Patent Literature 3: JP4-357324A
- Patent Literature 4: JP2006-77854A
-
- Non-Patent Literature 1: Tetsu-to-Hagane, 94 (2008), p.13
- Non-Patent Literature 2: Kazuhiko Hiraoka, Heisei 20-Nendo Academic Dissertation of University of Hyogo (January in 2008)
- The present invention is directed to a technology relating to (3) described in the above paragraph [0006] and is to provide a method for producing a mechanical part having a rolling portion superior in rolling fatigue life on the inner diameter surface of an annular workpiece material, by conducting plastic processing to improve the state of the interface between non-metallic inclusions and the matrix steel material contained in the steel material constituting the annular workpiece material, which is to be subjected to cold forging, as compared to the conventional method for producing the conventional steel material aiming at reducing the non-metallic inclusions and reducing the diameters of the non-metallic inclusions.
- According to the present invention, there is provided a method for producing a mechanical part superior in rolling fatigue life, wherein the mechanical part comprises a rolling portion for a rolling element to roll along an inner diameter surface of an annular workpiece material subjected to cold forging, wherein the method comprises the step of performing cold forging by applying a hydrostatic stress to the inner diameter surface of the annular workpiece material on which the rolling portion is to be formed, thereby forming the rolling portion on the inner diameter surface of the annular workpiece material for the rolling element to roll therealong and increasing an inner diameter of the annular workpiece material other than the rolling portion, so as to provide an annular mechanical part comprising the rolling portion superior in rolling fatigue life. The application of this hydrostatic pressure directs the cavities existing in the interface between non-metallic inclusions in the steel and the steel matrix to close, enabling production of a mechanical part superior in rolling fatigue life. The annular workpiece material to be subjected to cold forging is preferably a steel pipe or a hot forged ring.
- According to a preferred aspect of the present invention, there is provided the method in which the hydrostatic stress is at least 1000 MPa. Applying a hydrostatic stress of at least 1000 MPa during cold forging to form a rolling surface makes it possible to close the cavities existing in the interface between the non-metallic inclusions contained in the steel and the steel matrix and thus to produce a mechanical part superior in rolling fatigue life.
- According to the production method of the present invention, when a hydrostatic stress (preferably at least 1000 MPa) is applied to the annular workpiece material at cold forging, the cavities generated in the interface between the non-metallic inclusions and the steel matrix can be closed or reduced even without reducing the amount of the non-metallic inclusions and without reducing the diameters thereof at the time of producing the steel material. As a result, it is possible to avoid flaking which occurs due to rolling contact fatigue originated from non-metallic inclusions, enabling production of a mechanical part provided with a rolling portion having a significantly improved rolling fatigue life.
-
FIG. 1A is a schematic view explaining a cold forging process (before compression processing) for an annular matrix according to the present invention. -
FIG. 1B is a schematic view explaining a cold forging process (after compression processing) for the annular matrix according to the present invention. -
FIG. 2 is a longitudinal cross-sectional view of a rolling bearing produced in accordance with the method of the present invention. -
FIG. 3 is a diagram showing CAE analysis of the rolling bearing produced in accordance with the method of the present invention -
FIG. 4A is a conceptual diagram showing a non-metallic inclusion and cavities in the periphery thereof before cold forging. -
FIG. 4B is a conceptual diagram showing a non-metallic inclusion and cavities in the periphery thereof after cold forging. -
FIG. 5 is a conceptual diagram showing a non-metallic inclusion of a hot rolled steel material and cavities in the periphery thereof. - The steel material required for the production method of the present invention may be machine structural steel and bearing steel.
- These machine structural steels are generally produced as a steel material through 1) oxidation refining of molten steel in an arc melting furnace or a converter furnace, 2) reduction refining in a ladle refining furnace (LF), 3) rotary-flow vacuum degassing treatment by a rotary-flow vacuum degasser (RH treatment), 4) casting of steel ingot by continuous casting or ingot casting and 5) plastic working of steel ingot by hot rolling or hot forging and cold rolling or by cold rolling and cold forging.
- The
annular matrix 2 used in the production method of the present invention can be produced as follows. First of all, the steel material produced as described above (for example, steel materials defined in JIS G 4805 (2008), JIS G 4051 (2005), JIS G 4104 or JIS G 4105) is subjected to the process of the aforementioned plastic working to produce a steel material. This steel material is subjected to asset milling, extrusion processing or hot processing such as hot forging to be processed into a steel pipe or a hot forged ring, which is then cut to a predetermined length. Further, the outer diameter surface and the inner diameter surface of the cut steel pipe or hot forged ring are subjected to cutting processing, and thus provide a steel pipe or hot forged ring provided with predetermined dimensions as theannular matrix 2. - The process according to the present invention will be explained with reference to
FIG. 1 . Theannular matrix 2 in a predetermined configuration is subjected to appropriate lubrication processing to have a temperature around room temperature. Theannular matrix 2 is set within anannular retraining frame 1 in a press apparatus as shown inFIG. 1A . Dies 3 are arranged at upper and lower positions in therestraining frame 1 and are respectively fixed to moving parts (not shown) at upper and lower positions in the press apparatus. Following the start of a processing motion of the press apparatus, anupper punch 3 a of the fixeddie 3 and an annularupper punch 3 b arranged around theupper punch 3 a start a descending motion in the arrow direction. In theannular matrix 2 set in a predetermined position in the dies 3, the descendingupper punch 3 a and annularupper punch 3 b applies plastic working to theinner diameter 2 a and theupper end face 2 b of theannular matrix 2. In addition, following the descending of theupper punch 3 a and the annularupper punch 3 b, theannular matrix 2 is pushed downward, while at the same time alower punch 3 c and an annularlower punch 3 d of thedie 3 applies plastic working to theinner diameter 2 a and thelower end face 2 c of theannular matrix 2. That is, theupper end face 2 b of theannular matrix 2 is pushed downward following the descending of theupper punch 3 a and the annularupper punch 3 b. As a result, thelower end face 2 c of theannular matrix 2 is relatively pushed up by thelower punch 3 c and the annularlower punch 3 d. In the end stage of the processing, theannular matrix 2 is subjected to compression processing to receive a hydrostatic stress by cold forging from theupper punch 3 a and the annularupper punch 3 b as well as thelower punch 3 c and the annularlower punch 3 d, thereby closing thecavities 4 existing between the steel matrix of theannular matrix 2 and thenon-metallic inclusions 5. - As shown in
FIG. 1B , subjecting theannular matrix 2 to the above compression processing applies a hydrostatic stress to the vicinity of the rollingportion 6 in themechanical part 7 to be produced, thereby providing an effect of closing thecavities 4 existing between the steel matrix of theannular matrix 2 and thenon-metallic inclusions 5. In this case, in order to sufficiently attain the effect of closing thecavities 4, it is preferable that a hydrostatic stress of at least 1000 MPa be applied to the vicinity of the rollingportion 6 at cold forging. The application of such hydrostatic stress directs thecavities 4 existing between thenon-metallic inclusions 5 and the matrix steel of theannular matrix 2 to change so as to close thecavities 4 or to reduce the volume of thecavities 4. This change enables avoidance of flaking which occurs due to rolling contact fatigue originated fromnon-metallic inclusions 5. As a result, there can be obtained themechanical part 7 having the rollingportion 6 having a superior rolling fatigue life. - The present invention will be explained with reference to examples in view of implementing conditions and obtained results. The compositions of test pieces used as steel materials for the
annular matrix 2 are shown in Table 1. -
TABLE 1 Ingredients of Test pieces (unit: % by mass) Steel Type C Si Mn P S Cu Ni Mo Cr Al SUJ2 1.04 0.22 0.32 0.008 0.007 — — 0.03 1.44 0.011 SUJ3 1.00 0.55 1.01 0.007 0.008 0.03 0.05 0.01 0.99 — S45C 0.44 0.20 0.70 0.01 0.01 — — — — — S53C 0.52 0.20 0.65 0.01 0.01 — — — — — - This example was implemented on test pieces of steel types shown in Table 1. First of all, molten steel was subjected to an oxidation refining in an arc melting furnace, a reduction refining in a ladle refining furnace (LF), and a degassing processing in a rotary-flow vacuum degasser (RH) for reducing the oxygen content in the molten steel, which was then subjected to continuous casting to produce a steel ingot. The steel ingot was subjected to conventional hot rolling to provide a steel material, which was then processed to form a steel pipe by assel mill. The steel pipe was then subjected to conventional spheroidized annealing to prepare a steel pipe.
- The above-obtained steel pipe made of the test piece shown in Table 1 and having an outer diameter φ of 80 mm and a thickness of 8.7 mm was sawn to a steel pipe having a width of 27.2 mm in the longitudinal direction of the steel pipe, of which the outer diameter and the inner diameter were subjected to cutting processing to provide a steel pipe having an outer diameter φ of 78.5 mm and a thickness of 7.0 mm. This steel pipe was then subjected to conventional lubrication processing to provide an
annual matrix 2 for cold forging. Theannular matrix 2 was subjected to the following cold forging, as shown inFIG. 2 , by using dies 3 designed in such a way that a cold forged product having a width of 28.1 mm, an outer diameter φ of 79.0 mm could be obtained in which the central portion in the inner diameter had a projection 2 d having a width of 7.5 mm and an inner diameter φ of 61.8 mm and in which the rollingportion 6 had a largestinner diameter 2 a of 68.2 mm. The cold forging was performed in such a way that theannular matrix 2 and the dies 3 both have temperatures around room temperature and apply a processing load of 4000 to 4200 kN and a processing surface pressure of 1800 to 1900 MPa in accordance with the processing method using the dies 3 shown inFIG. 1 . - It is considered that the cold forging applies a hydrostatic stress of up to approximately 1500 MPa to the vicinity of the rolling
portion 6, as predicted from the CAE analysis diagram shown inFIG. 3 . -
FIG. 4A andFIG. 4B schematically show the change of thecavities 4 existing between thenon-metallic inclusion 5 and the steel as theannular matrix 2 from before to after the cold forging.FIG. 4A shows a configuration of thenon-metallic inclusion 5 in theannular matrix 2 before the cold forging, with thecavities 4 being formed adjacent to thenon-metallic inclusion 5. As shown inFIG. 4B , however, it was confirmed that thecavity 4 existing between thenon-metallic inclusion 5 and the steel as theannular matrix 2 was closed after the cold forging. - Further, in order to evaluate the rolling fatigue life of the
mechanical part 7 which is the effect of the present invention, molding loads and molding methods at cold forging were controlled to obtain various test pieces under four steel type conditions and five processing conditions as shown in Table 2. -
TABLE 2 Steel type conditions Steel type condition Steel type 1 SUJ2 2 SUJ3 3 S45C 4 S53C Processing conditions Processing Maximum initiation Molding hydrostatic Processing temperature Processing load stress condition (° C.) method (kN) (MPa) A 20 Compression 4000-4200 1500 processing B 20 Compression 2700-3000 1000 processing C 20 Compression 3200-3500 1250 processing D 20 Tension 2700-3000 −1000 processing (tension) E 1000 Compression 350-500 800 processing - These obtained test pieces were subjected to turning processing to form a bearing washer which is a member of a thrust rolling bearing, followed by quenching and tempering treatment. There were thus obtained a hardness of HRB 94 or more for S45C, a hardness of HRC 20 or more for S53C, and a hardness of HRC 58 or more for SUJ2 and SUJ3. The test pieces were further subjected to grinding to provide a thrust rolling bearing, followed by evaluation of the rolling fatigue life thereof. For the rolling body, a commercially available ball for the thrust rolling bearing was used.
- The evaluation results of the rolling fatigue life were shown in Table 3 in accordance with three-step criteria including A: excellent, B: good, and C: poor. For the evaluation, the number before hyphen “-” in the conditions in Table 3 refers to steel type condition in Table 2 while the alphabetical letter after hyphen “-” refers to processing condition in Table 2. Since the hardness is different from each other among steel types, the same evaluation cannot be made thereamong. Therefore, the evaluation of the rolling fatigue life was made based upon comparison among the same steel types. It was confirmed that as the maximum compression stress at cold forging increases toward 1500 MPa, the rolling fatigue life improves so as to be evaluated as “A.” On the other hand, in the case where the tension stress was applied to the vicinity of the rolling
portion 6 by cold forging, the evaluation was rendered “C” which means that the rolling fatigue life was not improved, as shown in conditions “1-D,” “2-D,” “3-D,” and “4-D” in Table 3 under which the processing was conducted in accordance with processing condition D of Table 2. On the other hand, although not shown in Table 3, there is also confirmed an effect that the rolling fatigue life improves even if production was conducted with hot forging. However, the cold forging according to the present invention is more advantageous in that the steel material temperature is not raised. -
TABLE 3 Evaluation of rolling Conditions fatigue life 1 - A A 1 - B B 1 - C B 1 - D C 1 - E B 2 - A A 2 - B B 2 - C B 2 - D C 2 - E B 3 - A A 3 - B B 3 - C B 3 - D C 3 - E B 4 - A A 4 - B B 4 - C B 4 - D C 4 - E B - From the evaluation results of the rolling fatigue life test implemented on the test pieces in accordance with the four steel type conditions and the five processing conditions as described above, it was found that by applying a predetermined compression stress (preferably at least 1000 MPa) to the vicinity of the rolling surface at cold forging, the
cavities 4 existing between thenon-metallic inclusions 5 and the steel as theannular matrix 2 were closed or reduced to achieve an improvement in rolling fatigue life. It goes without saying that similarly to the above, an improvement in rolling fatigue life can also be achieved in an outer race ring material of a double row raceway. - Test pieces are produced in the same way as in Example 1, except that hot forged rings are produced instead of the steel pipes. The method for producing the hot forged ring is as follows. First of all, molten steel was subjected to an oxidation refining in an arc melting furnace, a reduction refining in a ladle refining furnace (LF), and a degassing processing in a rotary-flow vacuum degasser (RH) for reducing the oxygen content in the molten steel, which was then subjected to continuous casting to produce a steel ingot. The steel ingot was subjected to conventional hot rolling to provide a steel material, which was then processed to form a billet by shear cutting. The billet was then subjected to hot forging to provide a hot forged ring having an outer diameter φ of 80 mm, a thickness of 8.7 mm and a width of 27.2 mm. The hot forged ring was subjected to conventional spheroidized annealing to prepare a hot forged ring. The outer diameter and the inner diameter of the hot forged ring made of the above-obtained test piece shown in Table 1 were subjected to cutting processing to provide a hot forged ring having an outer diameter φ of 78.5 mm and a thickness of 7.0 mm. The hot forged ring was then subjected to conventional lubrication processing to form an
annual matrix 2 for cold forging. Cold forging and its subsequent processes using theannular matrix 2 are the same as in Example 1. In this case, effects similar to those attained in Example 1 can also be attained.
Claims (6)
1. A method for producing a mechanical part superior in rolling fatigue life, wherein the mechanical part comprises a rolling portion for a rolling element to roll along an inner diameter surface of an annular workpiece material subjected to cold forging, wherein the method comprises the step of:
performing cold forging by applying a hydrostatic stress to the inner diameter surface of the annular workpiece material on which the rolling portion is to be formed, thereby forming the rolling portion on the inner diameter surface of the annular workpiece material for the rolling element to roll therealong and increasing an inner diameter of the annular workpiece material other than the rolling portion, so as to provide an annular mechanical part comprising the rolling portion superior in rolling fatigue life.
2. The method according to claim 1 , wherein the annular workpiece material to be subjected to cold forging is a steel pipe.
3. The method according to claim 1 , wherein the annular workpiece material to be subjected to cold forging is a hot forged ring.
4. The method according to any claim 1 , wherein the hydrostatic stress is at least 1000 MPa.
5. The method according to claim 2 , wherein the hydrostatic stress is at least 1000 MPa.
6. The method according to claim 3 , wherein the hydrostatic stress is at least 1000 MPa.
Applications Claiming Priority (5)
Application Number | Priority Date | Filing Date | Title |
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JP2009194962 | 2009-08-26 | ||
JP2009194962 | 2009-08-26 | ||
JP2010185927A JP5669128B2 (en) | 2009-08-26 | 2010-08-23 | Manufacturing method of machine parts with excellent rolling fatigue life |
JP2010185927 | 2010-08-23 | ||
PCT/JP2010/064255 WO2011024792A1 (en) | 2009-08-26 | 2010-08-24 | Method for manufacturing mechanical part excellent in rolling fatigue life |
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US20120210765A1 true US20120210765A1 (en) | 2012-08-23 |
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US13/390,793 Abandoned US20120210765A1 (en) | 2009-08-26 | 2010-08-24 | Method for Manufacturing Mechanical Part Excellent in Rolling Fatigue Life |
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US (1) | US20120210765A1 (en) |
JP (1) | JP5669128B2 (en) |
KR (1) | KR20120090942A (en) |
CN (1) | CN102574196B (en) |
WO (1) | WO2011024792A1 (en) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US11371559B2 (en) | 2018-03-22 | 2022-06-28 | Ntn Corporation | Rolling component, bearing, and method of manufacturing the same |
US11421732B2 (en) | 2017-11-24 | 2022-08-23 | Ntn Corporation | Rolling component, bearing, and method of manufacturing the same |
US20220389966A1 (en) * | 2021-06-08 | 2022-12-08 | Aktiebolaget Skf | Forged outer ring |
Families Citing this family (5)
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JP5896713B2 (en) * | 2011-12-09 | 2016-03-30 | 山陽特殊製鋼株式会社 | Manufacturing method of machine parts with excellent rolling fatigue life |
JP6376725B2 (en) * | 2012-08-10 | 2018-08-22 | 山陽特殊製鋼株式会社 | Steel member with excellent rolling fatigue life |
EP3042977B1 (en) * | 2013-09-05 | 2020-02-26 | NTN Corporation | Method of testing the suitability of use of a rolling component |
WO2019103039A1 (en) * | 2017-11-24 | 2019-05-31 | Ntn株式会社 | Rolling part, bearing, and production method therefor |
WO2022201014A1 (en) * | 2021-03-24 | 2022-09-29 | Tata Steel Limited | An apparatus for thickening a tube at its intermediate portion |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3286498A (en) * | 1964-02-03 | 1966-11-22 | Gen Electric | Compressive forming |
US20020162371A1 (en) * | 2001-05-01 | 2002-11-07 | Peter Hamstra | Method of pressure-ram-forming metal containers and the like |
US20080089631A1 (en) * | 2004-09-22 | 2008-04-17 | Nsk Ltd | Raceway Ring for Radial Ball Bearing and Manufacturing Method Thereof, and Manufacturing Method of High Accurate Ring and Manufacturing Apparatus Thereof |
US20100068549A1 (en) * | 2006-06-29 | 2010-03-18 | Tenaris Connections Ag | Seamless precision steel tubes with improved isotropic toughness at low temperature for hydraulic cylinders and process for obtaining the same |
US8424205B2 (en) * | 2007-01-22 | 2013-04-23 | Nsk, Ltd. | Method for manufacturing a bearing ring member |
Family Cites Families (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2755716B2 (en) * | 1989-08-28 | 1998-05-25 | エヌティエヌ株式会社 | Forging of double row ball bearing outer ring material |
CN1079715C (en) * | 1998-06-22 | 2002-02-27 | 星龙金属株式会社 | Method of producing socket plate for wobble plate compressors |
JP4639089B2 (en) * | 2004-01-07 | 2011-02-23 | 山陽特殊製鋼株式会社 | Method for manufacturing ring with inner peripheral projection made of hollow metal tube |
CN101184562B (en) * | 2005-05-26 | 2011-06-22 | 昭和电工株式会社 | Method and apparatus for hole punching |
-
2010
- 2010-08-23 JP JP2010185927A patent/JP5669128B2/en active Active
- 2010-08-24 CN CN201080037139.3A patent/CN102574196B/en active Active
- 2010-08-24 WO PCT/JP2010/064255 patent/WO2011024792A1/en active Application Filing
- 2010-08-24 KR KR1020127003897A patent/KR20120090942A/en active Search and Examination
- 2010-08-24 US US13/390,793 patent/US20120210765A1/en not_active Abandoned
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3286498A (en) * | 1964-02-03 | 1966-11-22 | Gen Electric | Compressive forming |
US20020162371A1 (en) * | 2001-05-01 | 2002-11-07 | Peter Hamstra | Method of pressure-ram-forming metal containers and the like |
US20080089631A1 (en) * | 2004-09-22 | 2008-04-17 | Nsk Ltd | Raceway Ring for Radial Ball Bearing and Manufacturing Method Thereof, and Manufacturing Method of High Accurate Ring and Manufacturing Apparatus Thereof |
US20100068549A1 (en) * | 2006-06-29 | 2010-03-18 | Tenaris Connections Ag | Seamless precision steel tubes with improved isotropic toughness at low temperature for hydraulic cylinders and process for obtaining the same |
US8424205B2 (en) * | 2007-01-22 | 2013-04-23 | Nsk, Ltd. | Method for manufacturing a bearing ring member |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US11421732B2 (en) | 2017-11-24 | 2022-08-23 | Ntn Corporation | Rolling component, bearing, and method of manufacturing the same |
US11371559B2 (en) | 2018-03-22 | 2022-06-28 | Ntn Corporation | Rolling component, bearing, and method of manufacturing the same |
US20220389966A1 (en) * | 2021-06-08 | 2022-12-08 | Aktiebolaget Skf | Forged outer ring |
US11867232B2 (en) * | 2021-06-08 | 2024-01-09 | Aktiebolaget Skf | Forged outer ring |
Also Published As
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CN102574196B (en) | 2016-02-10 |
CN102574196A (en) | 2012-07-11 |
JP5669128B2 (en) | 2015-02-12 |
WO2011024792A1 (en) | 2011-03-03 |
KR20120090942A (en) | 2012-08-17 |
JP2011067868A (en) | 2011-04-07 |
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