EP1407158A2 - Enhanced capacity bearing - Google Patents

Enhanced capacity bearing

Info

Publication number
EP1407158A2
EP1407158A2 EP02756191A EP02756191A EP1407158A2 EP 1407158 A2 EP1407158 A2 EP 1407158A2 EP 02756191 A EP02756191 A EP 02756191A EP 02756191 A EP02756191 A EP 02756191A EP 1407158 A2 EP1407158 A2 EP 1407158A2
Authority
EP
European Patent Office
Prior art keywords
bearing
bearing component
hardness
inner race
shaft
Prior art date
Legal status (The legal status 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 status listed.)
Withdrawn
Application number
EP02756191A
Other languages
German (de)
French (fr)
Inventor
Robert Telakowski
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Hamilton Sundstrand Corp
Original Assignee
Hamilton Sundstrand Corp
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 Hamilton Sundstrand Corp filed Critical Hamilton Sundstrand Corp
Publication of EP1407158A2 publication Critical patent/EP1407158A2/en
Withdrawn legal-status Critical Current

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02C—GAS-TURBINE PLANTS; AIR INTAKES FOR JET-PROPULSION PLANTS; CONTROLLING FUEL SUPPLY IN AIR-BREATHING JET-PROPULSION PLANTS
    • F02C7/00—Features, components parts, details or accessories, not provided for in, or of interest apart form groups F02C1/00 - F02C6/00; Air intakes for jet-propulsion plants
    • F02C7/06—Arrangements of bearings; Lubricating
    • 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
    • C23C8/24—Nitriding
    • C23C8/26—Nitriding 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
    • F16C33/00—Parts of bearings; Special methods for making bearings or parts thereof
    • F16C33/30—Parts of ball or roller bearings
    • F16C33/58—Raceways; Race rings
    • F16C33/62—Selection of substances
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C33/00—Parts of bearings; Special methods for making bearings or parts thereof
    • F16C33/30—Parts of ball or roller bearings
    • F16C33/58—Raceways; Race rings
    • F16C33/64—Special methods of manufacture

Definitions

  • This invention relates to an improved bearing, and more specifically, the invention relates to an improved bearing particularly suitable for turbines used in the aerospace industry.
  • bearing life standards are based upon an SAE 52100 steel, which typically has a hardness in the range of 60 to 62 Re.
  • a premium grade steel such as M50
  • M50 materials are frequently used in the aerospace industry for such components as turbine bearings, for which extended bearing life is particularly desirable. In spite of the increased bearing life that 50 provides, further improvements are desirable to increase bearing durability.
  • Increased bearing life may also be achieved by utilizing alternative materials such as ceramics.
  • ceramics are an exotic material which may cost significantly more than a premium grade steel such as M50.
  • the size of the bearing may also be increased to increase the bearing life. However, by increasing the size of the bearing weight is added and it may be more difficult to package the bearing.
  • coatings may be added to the bearing surfaces to reduce wear and increase the life of the bearing. However, once the coatings wear from the bearing, the bearing life may rapidly decrease. The coating must be carefully selected to provide sufficient adhesion between the coating and the base material. Nitriding is a known process used to increase the case hardness, or surface hardness, of a component.
  • nitriding has not been applied to turbine applications, and particularly nitriding has not been applied to premium grade thru hardened steel such as M50.
  • Prior art bearing materials does not provide adequate hardness in the event that the case hardened portion wears through. Therefore, what is needed is a hardened premium grade steel particularly suitable for aerospace applications such as turbines.
  • the present invention provides a bearing particularly suitable for a turbine and turbine related components used in the aerospace industry. More particularly, the bearing is suitable for such applications as pneumatic starters for turbines.
  • the bearing is preferably constructed from a thru hardened M50 steel, which typically has a pre-treated hardness in the range of approximately 60 to 64 Re. With the present invention, the bearing is nitrided to obtain a case hardness of approximately 74 Re. To achieve such a case hardness, the bearing may require nitriding over several days.
  • a pneumatic starter includes a planetary gear assembly having a shaft, which is the life limiting component for particular applications.
  • the shaft is preferably constructed from M50 alloy steel that has a portion of its outer surface nitrided.
  • the nitrided surface functions as an inner race of a bearing assembly. Nitriding the portion of the shaft extends the bearing life of the bearing due to its increased hardness.
  • a bearing having an increased bearing life without utilizing alternative materials or increasing the size of the bearing.
  • Figure 1 is a cross-sectional view of a turbine having a pneumatic starter
  • Figure 2 is a schematic view of a nitriding process for bearings of the present invention.
  • Achieving increased bearing life and improved performance of bearings is critical for many applications. For example, increasing bearing life for bearings used in aerospace applications such as turbine starters is desirable to increase durability and reliability.
  • bearing life standards are based upon an SAE 52100 steel, which has a hardness of typically in the range of 60 to 62 Re. Increasing the hardness of a life limiting bearing component may have the effect of extending the overall bearing life and lengthening the service interval of the components associated with the bearing.
  • a turbine starter 10 commonly used in the aerospace industry is shown in Figure 1. The starter 10 includes a portion of a planetary gear assembly 12 supported within a housing by a bearing assembly 14.
  • Bearing assemblies typically includes an inner race, an outer race, and a plurality of rolling elements arranged between the inner and outer races to reduce the friction there between.
  • the inner race may be defined by an exterior surface of a gear shaft 16
  • the outer race may be defined by an inner diameter of a planetary gear 18.
  • the gear shaft 16 is supported by the planetary gear 18 and a plurality of rolling elements 20, such as needle or tapered rollers, arranged between the gear shaft 16 and planetary gear 18.
  • Premium grade, high speed steels are commonly used in the aerospace industries due to their increased hardness and extended life as compared to standard bearing materials such as SAE 52100 steels.
  • M50 alloys typically have a maximum hardness of approximately 64 Re.
  • the gear shaft 16 of the pneumatic starter 10 may be nitrided.
  • the gear shaft 16 is preferably constructed from a M50 alloy. Referring to Figure 2, the untreated gear shaft 32 would be loaded into a chamber 34 for nitriding. Ammonia gas or another suitable nitrogen rich mixture 36 is provided to the chamber 34.
  • the gear shaft 32 remains in the nitrogen rich atmosphere within the chamber 34 to increase the nitrogen content of the exterior portion of the gear shaft 16 and thereby increase the case hardness.
  • the case hardness, or depth of the hardness is dependent upon the temperature within the chamber 34 and the time the gear shaft 16 spends within the chamber 34, among other factors. By nitriding the gear shaft 16 for several days in the chamber 34 a case hardness of approximately 74 Re may be achieved. If the case hardened portion of the bearing wears through, the underlying unhardened M50 material provides considerable wear resistance. In this manner, the bearing life may be increased by at least three-fold.

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Combustion & Propulsion (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)
  • Rolling Contact Bearings (AREA)

Abstract

A bearing is provided particularly suitable for a turbine and turbine related components used in the aerospace industry. More particularly, the bearing is suitable for such applications as pneumatic starters for turbines. The bearing is preferably constructed from a M50 steel, which typically has a pre-treated hardness in the range of approximately 60 to 64 Rc. With the present invention, the bearing is nitrided to obtain a case hardness of approximately 74 Rc. To achieve such a case hardness, the bearing may require nitriding over several days. In one preferred embodiment of the present invention, a pneumatic starter includes a shaft, preferably constructed from M50, that has a portion of its outer surface nitrided. The nitrided surface functions as an inner race of a bearing assembly. Nitriding the portion of the shaft extends the bearing life of the bearing due to its increased harness.

Description

ENHANCED CAPACITY BEARING
Technical Field
This invention relates to an improved bearing, and more specifically, the invention relates to an improved bearing particularly suitable for turbines used in the aerospace industry.
It is desirable to increase the life of bearings to decrease the amount of service necessary for the bearing and the components associated with the bearing. One way of increasing the bearing life is to increase the hardness of the bearing to reduce bearing wear. One way to increase bearing hardness is to utilize a premium grade steel which provides increased hardness. For example, bearing life standards are based upon an SAE 52100 steel, which typically has a hardness in the range of 60 to 62 Re. By utilizing a premium grade steel such as M50, a hardness in the range of 64 Re may be obtained thereby increasing the bearing fatigue life. M50 materials are frequently used in the aerospace industry for such components as turbine bearings, for which extended bearing life is particularly desirable. In spite of the increased bearing life that 50 provides, further improvements are desirable to increase bearing durability. Increased bearing life may also be achieved by utilizing alternative materials such as ceramics. However, ceramics are an exotic material which may cost significantly more than a premium grade steel such as M50. The size of the bearing may also be increased to increase the bearing life. However, by increasing the size of the bearing weight is added and it may be more difficult to package the bearing. Alternatively, coatings may be added to the bearing surfaces to reduce wear and increase the life of the bearing. However, once the coatings wear from the bearing, the bearing life may rapidly decrease. The coating must be carefully selected to provide sufficient adhesion between the coating and the base material. Nitriding is a known process used to increase the case hardness, or surface hardness, of a component. However, nitriding has not been applied to turbine applications, and particularly nitriding has not been applied to premium grade thru hardened steel such as M50. Prior art bearing materials does not provide adequate hardness in the event that the case hardened portion wears through. Therefore, what is needed is a hardened premium grade steel particularly suitable for aerospace applications such as turbines.
Disclosure of Invention
The present invention provides a bearing particularly suitable for a turbine and turbine related components used in the aerospace industry. More particularly, the bearing is suitable for such applications as pneumatic starters for turbines. The bearing is preferably constructed from a thru hardened M50 steel, which typically has a pre-treated hardness in the range of approximately 60 to 64 Re. With the present invention, the bearing is nitrided to obtain a case hardness of approximately 74 Re. To achieve such a case hardness, the bearing may require nitriding over several days.
In one preferred embodiment of the present invention, a pneumatic starter includes a planetary gear assembly having a shaft, which is the life limiting component for particular applications. The shaft is preferably constructed from M50 alloy steel that has a portion of its outer surface nitrided. The nitrided surface functions as an inner race of a bearing assembly. Nitriding the portion of the shaft extends the bearing life of the bearing due to its increased hardness.
Accordingly, a bearing is provided having an increased bearing life without utilizing alternative materials or increasing the size of the bearing.
Brief Description of Drawings
Other advantages of the present invention can be understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein: Figure 1 is a cross-sectional view of a turbine having a pneumatic starter; and
Figure 2 is a schematic view of a nitriding process for bearings of the present invention.
Best Mode for Carrying Out the Invention
Achieving increased bearing life and improved performance of bearings is critical for many applications. For example, increasing bearing life for bearings used in aerospace applications such as turbine starters is desirable to increase durability and reliability. In the bearing industry, bearing life standards are based upon an SAE 52100 steel, which has a hardness of typically in the range of 60 to 62 Re. Increasing the hardness of a life limiting bearing component may have the effect of extending the overall bearing life and lengthening the service interval of the components associated with the bearing. A turbine starter 10 commonly used in the aerospace industry is shown in Figure 1. The starter 10 includes a portion of a planetary gear assembly 12 supported within a housing by a bearing assembly 14. Bearing assemblies typically includes an inner race, an outer race, and a plurality of rolling elements arranged between the inner and outer races to reduce the friction there between. In the embodiments shown, the inner race may be defined by an exterior surface of a gear shaft 16, and the outer race may be defined by an inner diameter of a planetary gear 18. The gear shaft 16 is supported by the planetary gear 18 and a plurality of rolling elements 20, such as needle or tapered rollers, arranged between the gear shaft 16 and planetary gear 18. Premium grade, high speed steels are commonly used in the aerospace industries due to their increased hardness and extended life as compared to standard bearing materials such as SAE 52100 steels. M50 alloys typically have a maximum hardness of approximately 64 Re. Despite the increased hardness and improved bearing life provided by M50 alloys, it is desirable to further extend bearing life. Depending on the particular application, a different part of the bearing assembly may be more highly stressed than another bearing component and therefore have a shorter fatigue life. For example, the inner race of the gear shaft 16 may fatigue earlier than the other bearing components. Accordingly, it is desirable to increase the hardness of the inner race. In one preferred embodiment, the gear shaft 16 of the pneumatic starter 10 may be nitrided. The gear shaft 16 is preferably constructed from a M50 alloy. Referring to Figure 2, the untreated gear shaft 32 would be loaded into a chamber 34 for nitriding. Ammonia gas or another suitable nitrogen rich mixture 36 is provided to the chamber 34. The gear shaft 32 remains in the nitrogen rich atmosphere within the chamber 34 to increase the nitrogen content of the exterior portion of the gear shaft 16 and thereby increase the case hardness. The case hardness, or depth of the hardness, is dependent upon the temperature within the chamber 34 and the time the gear shaft 16 spends within the chamber 34, among other factors. By nitriding the gear shaft 16 for several days in the chamber 34 a case hardness of approximately 74 Re may be achieved. If the case hardened portion of the bearing wears through, the underlying unhardened M50 material provides considerable wear resistance. In this manner, the bearing life may be increased by at least three-fold. The invention has been described in an illustrative manner, and it is to be understood that the terminology that has been used is intended to be in the nature of words of description rather than of limitation. Obviously, many modifications and variations of the present invention are possible in light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

Claims

Claims
1. A bearing component constructed from a M50 alloy with a nitrided case having a case hardness of approximately 74 Re.
2. The bearing component according to claim 1 , wherein said thru hardened M50 alloy has a pre-treated hardness in a range of approximately 60 to 64 Re.
3. The bearing component according to claim 1 , wherein said bearing component is an inner race.
4. The bearing component according to claim 3, wherein said inner race is a shaft of a pneumatic starter for a turbine engine.
5. A method of manufacturing a bearing comprising the steps of: a) providing a bearing component constructed from a M50 alloy; b) nitriding the bearing component to increase the nitrogen content of an exterior portion of the bearing component; and c) achieving a case hardness of approximately 74 Re.
6. The method according to claim 5, wherein said bearing component is an inner race.
7. The method according to claim 6, wherein said inner race is a shaft of a pneumatic starter for a turbine.
8. A starter comprising: a housing; planetary gear assembly supported within said housing; and a bearing assembly arranged within said planetary gear assembly wherein a portion of said bearing assembly is constructed from a nitrided high speed steel.
9. The starter according to claim 8, wherein said high speed steel is a M50 alloy.
10. The starter according to claim 8, wherein said bearing component is an inner race.
11. The starter according to claim 9, wherein planetary gear assembly includes a shaft with a portion of said shaft providing said inner.
EP02756191A 2001-07-17 2002-06-13 Enhanced capacity bearing Withdrawn EP1407158A2 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
US09/907,462 US20030201033A1 (en) 2001-07-17 2001-07-17 Enhanced capacity bearing
US907462 2001-07-17
PCT/US2002/018934 WO2003008822A2 (en) 2001-07-17 2002-06-13 Enhanced capacity bearing

Publications (1)

Publication Number Publication Date
EP1407158A2 true EP1407158A2 (en) 2004-04-14

Family

ID=25424133

Family Applications (1)

Application Number Title Priority Date Filing Date
EP02756191A Withdrawn EP1407158A2 (en) 2001-07-17 2002-06-13 Enhanced capacity bearing

Country Status (3)

Country Link
US (1) US20030201033A1 (en)
EP (1) EP1407158A2 (en)
WO (1) WO2003008822A2 (en)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8033736B2 (en) * 2007-07-12 2011-10-11 Roller Bearing Company Of America, Inc. Swashplate bearing assembly with enhanced alloys
WO2009152543A1 (en) 2008-06-17 2009-12-23 Erber Aktiengesellschaft Immunochromatographic method and test system for determining at least one analyte in a test solution under examination
US10526909B2 (en) 2014-01-20 2020-01-07 United Technologies Corporation Lightweight journal support pin
CN107315861B (en) * 2017-05-16 2020-06-19 沈阳透平机械股份有限公司 Calculation and judgment method for bearing capacity of ion nitriding gear

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1603832A (en) * 1977-05-31 1981-12-02 British Leyland Cars Ltd Method for the gaseous nitriding of ferrous metal components
EP0592352B1 (en) * 1992-10-05 1996-12-04 United Technologies Corporation Flyweight actuated clutch
JP3241491B2 (en) * 1993-06-29 2001-12-25 大同特殊鋼株式会社 Rolling bearing for high temperature and high speed rotation
JP3750202B2 (en) * 1996-02-21 2006-03-01 日本精工株式会社 Rolling bearing
DE69835281T2 (en) * 1997-04-03 2007-08-09 Jtekt Corp., Osaka ROLLER BEARING
US6248186B1 (en) * 1997-11-07 2001-06-19 Nsk Ltd. Ball-and-roller bearing and method of manufacturing the same

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO03008822A3 *

Also Published As

Publication number Publication date
US20030201033A1 (en) 2003-10-30
WO2003008822A2 (en) 2003-01-30
WO2003008822A3 (en) 2003-05-08

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