JP2017150593A - Roller bearing for cryogenic environment - Google Patents

Roller bearing for cryogenic environment Download PDF

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JP2017150593A
JP2017150593A JP2016034422A JP2016034422A JP2017150593A JP 2017150593 A JP2017150593 A JP 2017150593A JP 2016034422 A JP2016034422 A JP 2016034422A JP 2016034422 A JP2016034422 A JP 2016034422A JP 2017150593 A JP2017150593 A JP 2017150593A
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rolling
clearance
ring
diameter
cage
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鈴木 康介
Kosuke Suzuki
康介 鈴木
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Ntn株式会社
Ntn Corp
Ntn株式会社
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    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04DNON-POSITIVE-DISPLACEMENT PUMPS
    • F04D7/00Pumps adapted for handling specific fluids, e.g. by selection of specific materials for pumps or pump parts
    • F04D7/02Pumps adapted for handling specific fluids, e.g. by selection of specific materials for pumps or pump parts of centrifugal type
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16CSHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C19/00Bearings with rolling contact, for exclusively rotary movement
    • F16C19/02Bearings with rolling contact, for exclusively rotary movement with bearing balls essentially of the same size in one or more circular rows
    • F16C19/04Bearings with rolling contact, for exclusively rotary movement with bearing balls essentially of the same size in one or more circular rows for radial load mainly
    • F16C19/06Bearings with rolling contact, for exclusively rotary movement with bearing balls essentially of the same size in one or more circular rows for radial load mainly with a single row or balls
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16CSHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C33/00Parts of bearings; Special methods for making bearings or parts thereof
    • F16C33/30Parts of ball or roller bearings
    • F16C33/32Balls
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16CSHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C33/00Parts of bearings; Special methods for making bearings or parts thereof
    • F16C33/30Parts of ball or roller bearings
    • F16C33/38Ball cages
    • F16C33/44Selection of substances
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16CSHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C33/00Parts of bearings; Special methods for making bearings or parts thereof
    • F16C33/30Parts of ball or roller bearings
    • F16C33/58Raceways; Race rings
    • F16C33/62Selection of substances
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04DNON-POSITIVE-DISPLACEMENT PUMPS
    • F04D29/00Details, component parts, or accessories
    • F04D29/04Shafts or bearings, or assemblies thereof
    • F04D29/046Bearings

Abstract

PROBLEM TO BE SOLVED: To perform a positive prevention of poor rotation of a roller bearing component element caused by a variation in size under cryogenic temperature in regard to a guide clearance or a radial inner clearance for use in supplying solid lubricant agent through contact with a cage by arranging a clearance between respective component elements at the time of assembly under normal temperature set in a specified range in order to prevent a poor rotation of a roller bearing used in the cryogenic state.SOLUTION: This invention relates to a roller bearing for cryogenic environment in which an inner ring 1 and an outer ring 2 are made of martensitic stainless steel or high speed tool steel, a rolling element 3 is a ceramics rolling element, a cage 4 is made of resin material and a clearance ratio C at a normal temperature (20°C) is 2.5 to 4. Provided that the clearance ratio C=(a diameter of the rolling element×a guide clearance)/(an outer diameter of the inner ring×a radial inner clearance) and the guide clearance in the formula is a clearance width between an outer diameter surface of the inner ring and an inner diameter surface of the cage and the radial inner clearance is a clearance width between the raceway of the outer ring and the surface of the rolling element. A variation in size about the guide clearance or the radial inner clearance for use in supplying solid lubricant agent under a cryogenic temperature through contact with the cage is restricted and the poor rotation of the bearing is positively prevented.SELECTED DRAWING: Figure 1

Description

この発明は、液化天然ガスなどの極低温状態の液化ガスを移送するサブマージドポンプに用いられる軸受のように、極低温下で用いられる極低温環境用転がり軸受に関するものである。   The present invention relates to a rolling bearing for a cryogenic environment used at a cryogenic temperature, such as a bearing used in a submerged pump that transports a cryogenic gas such as liquefied natural gas.
一般に、常温の環境で用いられる転がり軸受は、内輪と外輪の間に転動体を回転自在に保持し、潤滑油等による液体潤滑が必要であるが、例えば−100℃以下または−200℃以下のような極低温の液化ガス等が存在する環境や、これらを取り扱う環境下で用いられる転がり軸受には、通常の潤滑油等による液体潤滑を期待できない。また、極低温環境用転がり軸受には、部品の収縮変形に伴う強度や耐久性の低下などが起こりやすいこともあり、そのような厳しい使用条件に耐える特性が必要である。   In general, a rolling bearing used in a normal temperature environment requires a rolling element to be rotatably supported between an inner ring and an outer ring, and liquid lubrication with a lubricating oil or the like is required, but for example, −100 ° C. or less or −200 ° C. or less. In a rolling bearing used in an environment where such a cryogenic liquefied gas or the like exists, or in an environment where these gases are handled, liquid lubrication with a normal lubricating oil or the like cannot be expected. In addition, rolling bearings for cryogenic environments are liable to deteriorate in strength and durability due to shrinkage and deformation of parts, and are required to withstand such severe use conditions.
因みに、極低温の液化ガスの代表例である液化天然ガス(LNG)は、メタンを主成分とし、常圧下では−161.5℃(約−162℃)以下でなければ液化しない物性である。LNGの他にも、例えば冷媒、熱媒体、充填用ガスなどに液化された状態で利用される液化ガスとして、窒素、ヘリウムなどがある。   Incidentally, liquefied natural gas (LNG), which is a typical example of a cryogenic liquefied gas, has methane as a main component, and has a physical property that does not liquefy unless it is −161.5 ° C. (about −162 ° C.) or lower under normal pressure. In addition to LNG, examples of liquefied gas used in a liquefied state such as a refrigerant, a heat medium, and a filling gas include nitrogen and helium.
このような液化ガスを極低温で液体の状態を維持して移送したり保管したりする場合、極低温下での専用ポンプを用いる必要があり、そのようなポンプの型式としてサブマージド型のポンプが知られている。
この型式のポンプは、モータを含むポンプ装置の全体を液化ガス中に浸漬して用いるので、本体を外気から密封するためのメカニカルシールを必要とせず、気化ガスの散逸によるロスの少ない点でも優れたものである。
When transporting or storing such a liquefied gas while maintaining a liquid state at a cryogenic temperature, it is necessary to use a dedicated pump at a cryogenic temperature. As a type of such a pump, a submerged pump is used. Are known.
Since this type of pump is used by immersing the entire pump device including the motor in liquefied gas, it does not require a mechanical seal to seal the main body from the outside air, and is excellent in that there is little loss due to dissipation of the vaporized gas. It is a thing.
このようなサブマージド型のポンプは、モータなども直接に液化ガスに触れる状態で用いられるので、モータ軸などを支持する転がり軸受についても極低温下で潤滑性に乏しいLNGなどの液化ガスで潤滑されながら、耐久性がよく安定して良好な回転状態であることが求められる。   Since such a submerged pump is used in a state where the motor and the like are in direct contact with the liquefied gas, the rolling bearing supporting the motor shaft and the like is also lubricated with a liquefied gas such as LNG having poor lubricity at extremely low temperatures. However, it is required to have a good rotation state with good durability and stability.
また、極低温環境の他の例としては、上記した液化ガスの存在する環境ばかりではなく、地表から遠く離れた成層圏以上の高高度の宇宙空間や、さらに離れた宇宙空間でも、環境温度は−50〜−270℃程度になることから、そのような人工衛星や宇宙船で用いられる極低温環境用転がり軸受にも同様な特性が求められる。   As another example of the cryogenic environment, not only the environment where the liquefied gas exists, but also the high temperature space beyond the stratosphere far from the surface of the earth and the space temperature farther away, the environmental temperature is − Since it becomes about 50-270 degreeC, the same characteristic is calculated | required also for the rolling bearing for cryogenic environments used with such an artificial satellite or a spacecraft.
このような極低温環境で用いられる転がり軸受の公知技術として、外輪および内輪がマルテンサイト系ステンレス鋼で形成され、かつ転動体がセラミックで形成され、保持器はフッ素樹脂で形成されたものが知られている(特許文献1)。   As a known technique of a rolling bearing used in such a cryogenic environment, an outer ring and an inner ring are made of martensitic stainless steel, a rolling element is made of ceramic, and a cage is made of a fluororesin. (Patent Document 1).
特開2014−20490号公報JP 2014-20490 A
しかし、上記した極低温環境で用いられる転がり軸受は、内輪、外輪、転動体、及び保持器の素材を特定して、低温化による寸法変化を生じ難くしたものに過ぎず、転がり軸受を常温で組み立てるときの部品寸法まで、特定されたものではなかった。
すなわち、従来の極低温環境用の転がり軸受では、外輪、内輪、転動体、保持器を所定の素材からなる極低温での熱収縮の少ない材質を採用しても、ある程度は低温化による寸法変化を甘受せざるを得ない。
However, the rolling bearings used in the cryogenic environment described above are only those in which the material of the inner ring, outer ring, rolling element, and cage is specified to make it difficult to cause dimensional changes due to low temperatures. The dimensions of the parts when assembled were not specified.
In other words, in conventional rolling bearings for cryogenic environments, even if outer rings, inner rings, rolling elements, and cages are made of a predetermined material and have a low heat shrinkage at a very low temperature, the dimensional change due to low temperatures is to some extent. I have to accept it.
例えば、極低温下での転がり軸受の樹脂素材からなる保持器の案内形式として、以下の(1)〜(3)の対応がある。
(1)転動体案内:転動体と保持器ポケット間に予定される熱収縮に対応する隙間を空けて、適度の接触を図る。
(2)内輪案内:内輪外径と保持器内径間に予定される熱収縮に対応する隙間を空けて、適度の接触を図る。
(3)外輪案内:外輪内径と保持器外径間に予定される熱収縮に対応する隙間を空けて、適度の接触を図る。
For example, there are the following correspondences (1) to (3) as a guide type for a cage made of a resin material of a rolling bearing at an extremely low temperature.
(1) Rolling element guide: A gap corresponding to the expected heat shrinkage is provided between the rolling element and the cage pocket to achieve appropriate contact.
(2) Inner ring guide: A gap corresponding to the expected heat shrinkage is provided between the outer diameter of the inner ring and the inner diameter of the cage to achieve appropriate contact.
(3) Outer ring guide: A gap corresponding to the expected heat shrinkage between the inner diameter of the outer ring and the outer diameter of the cage is provided to achieve appropriate contact.
これらの場合において、特に鋼材製の内外輪およびセラミックス製の転動体が採用されている場合には、鋼材やセラミックスよりも樹脂材の方が線膨張係数は大きいことから、極低温下において、(1)では、保持器の収縮が転動体の収縮より大きく、保持器は転動体の回転を妨げる可能性がある。また、(2)では、常温下での隙間の適切な設定が困難であり、理論的には保持器の外径が外輪内径より大きくする必要が生じて、設計は困難になってしまう。   In these cases, particularly when steel inner and outer rings and ceramic rolling elements are employed, since the linear expansion coefficient of the resin material is larger than that of the steel material or ceramic, In 1), the contraction of the cage is larger than the contraction of the rolling element, and the cage may impede the rotation of the rolling element. In (2), it is difficult to appropriately set the gap at room temperature. Theoretically, the outer diameter of the cage needs to be larger than the inner diameter of the outer ring, which makes designing difficult.
また、上記(3)の対応を採用した場合には、常温での軸受組み立て時の各部品間の隙間をどのようにすれば、極低温下での軸受の回転不良を防止できるのか不明であり、多くの試行錯誤を伴う非容易性があった。   In addition, when adopting the measure (3) above, it is unclear how the gaps between parts during assembly of bearings at room temperature can be prevented to prevent poor rotation of the bearings at extremely low temperatures. There was a lot of trial-and-error and non-easiness.
そこで、この発明の課題は上記した問題点を解決し、極低温下で使用される転がり軸受の回転不良を防止するため、常温での組み立て時の各部品間の隙間を所定範囲に設けることにより、特に固体潤滑剤を保持器からの接触で供給するための案内隙間や、ラジアル内部隙間について極低温下での転がり軸受部品の寸法変化による回転不良を確実に防止することである。   Therefore, the object of the present invention is to solve the above-mentioned problems and to provide clearances between parts in a predetermined range during assembly at room temperature in order to prevent rotation failure of a rolling bearing used at an extremely low temperature. In particular, it is to reliably prevent a rotation failure due to a change in dimensions of a rolling bearing component at a cryogenic temperature in a guide gap for supplying a solid lubricant by contact from a cage or a radial internal gap.
上記の課題を解決するため、この発明では、マルテンサイト系ステンレス鋼または高速度工具鋼からなる内・外輪の内・外径面間に、複数の転動体を回転自在に保持する保持器を設けた転がり軸受において、前記転動体は、セラミックス製の転動体であり、前記保持器は樹脂素材からなり、以下の式で示される常温(20℃)の隙間比率Cが2.5〜4であることを特徴とする極低温環境用転がり軸受としたのである。   In order to solve the above problems, in the present invention, a cage for rotatably holding a plurality of rolling elements is provided between inner and outer diameter surfaces of inner and outer rings made of martensitic stainless steel or high-speed tool steel. In the rolling bearing, the rolling element is a ceramic rolling element, the cage is made of a resin material, and a gap ratio C at a normal temperature (20 ° C.) represented by the following formula is 2.5 to 4. This is a rolling bearing for a cryogenic environment characterized by this.
隙間比率C=(転動体径×案内隙間)/(内輪外径×ラジアル内部隙間)
(上記の式中、案内隙間=内輪外径面と保持器内径面との隙間幅であり、ラジアル内部隙間=外輪軌道面と転動体表面との隙間幅である。)
Clearance ratio C = (Rolling element diameter × Guide clearance) / (Inner ring outer diameter × Radial internal clearance)
(In the above formula, the guide gap is the gap width between the inner ring outer diameter surface and the cage inner diameter surface, and the radial inner gap is the gap width between the outer ring raceway surface and the rolling element surface.)
上記したように構成されるこの発明の極低温環境用転がり軸受は、常温(20℃)で組み立てられる際に、内輪外径面と保持器内径面との隙間(mm)が、常温またはそれ以上の温度で使用される通常の用途の転がり軸受の同箇所の間隔として、技術常識を超える大きな隙間幅のものである。   When the rolling bearing for the cryogenic environment of the present invention configured as described above is assembled at room temperature (20 ° C.), the clearance (mm) between the outer surface of the inner ring and the inner surface of the cage is at room temperature or higher. As the interval of the same location of the rolling bearing of a normal use used at a temperature of 5 mm, it has a large gap width exceeding the technical common sense.
すなわち、極低温環境用転がり軸受が、常温(20℃)で組み立てられた際には、内輪外径面と保持器内径面との案内隙間およびラジアル内部隙間は、常温(20℃)から極低温下(−196℃)まで冷却されるまでの温度差と、内・外輪と保持器のそれぞれの熱膨張率差を考慮して、上記した隙間比率Cが2.5〜4に設けられる。   That is, when a rolling bearing for a cryogenic environment is assembled at room temperature (20 ° C.), the guide gap and the radial inner gap between the inner ring outer diameter surface and the cage inner diameter surface are from ordinary temperature (20 ° C.) to cryogenic temperature. Taking into account the temperature difference until cooling down (−196 ° C.) and the difference in thermal expansion coefficient between the inner and outer rings and the cage, the gap ratio C described above is set to 2.5-4.
樹脂製の保持器の主成分としては、ポリテトラフルオロエチレン、ポリプロピレン、ポリスチレン、アクリロニトリルスチレン、アクリロニトリル−ブタジエン−スチレンプラスチック、ポリ三フッ化塩化エチレン、ポリカーボネート、ポリメチルメタクリレート、ポリアミド6、ポリアミド66、ポリスルホン、ポリフェニレンオキシド、フェノール樹脂、エポキシ樹脂、不飽和ポリエステル樹脂、ユリア樹脂、メラミン樹脂などが用いられるが、極低温下(−196℃)の使用状態においては、特にポリテトラフルオロエチレン(PTFE)が好ましい。PTFE系樹脂製の保持器の場合、保持器の内径面と、マルテンサイト系ステンレス鋼または高速度工具鋼からなる所定鋼材製の内輪外径面とが、適当な頻度で接触し、保持器表面のPTFE系樹脂が内輪外径面に移着して良好な潤滑性が発揮される。   The main components of the resin cage are polytetrafluoroethylene, polypropylene, polystyrene, acrylonitrile styrene, acrylonitrile-butadiene-styrene plastic, polytrifluoroethylene chloride, polycarbonate, polymethyl methacrylate, polyamide 6, polyamide 66, polysulfone. , Polyphenylene oxide, phenol resin, epoxy resin, unsaturated polyester resin, urea resin, melamine resin, etc. are used, but polytetrafluoroethylene (PTFE) is particularly preferable in the use state at extremely low temperature (−196 ° C.). . In the case of a cage made of PTFE resin, the inner surface of the cage and the inner ring outer diameter surface made of a predetermined steel material made of martensite stainless steel or high-speed tool steel come into contact with each other at an appropriate frequency. The PTFE-based resin is transferred to the outer surface of the inner ring and exhibits good lubricity.
ここで、隙間比率Cは、単に各部品の材質の熱膨張率と温度だけで計算により求められるものではなく、使用中に軌道輪に係る荷重や、外輪の径方向への移動量、各部品の弾性変形量に関わり、これらの影響下に前記した式に従って、隙間比率Cを求め、軸受部品の寸法変化による回転不良を確実に防止でき良好な回転状態になる適切な数値を実験的に見つけだすことにより、特定することができたものである。   Here, the clearance ratio C is not simply obtained by calculation based only on the thermal expansion coefficient and temperature of the material of each component, but the load on the bearing ring during use, the amount of movement of the outer ring in the radial direction, Under these influences, the clearance ratio C is obtained according to the above-described formula, and an appropriate numerical value that can reliably prevent a rotation failure due to a change in the dimensions of the bearing component and achieve a good rotation state is experimentally found. It was possible to specify.
また、この発明の極低温環境用転がり軸受は、マルテンサイト系ステンレス鋼または高速度工具鋼からなる内輪と外輪が、極低温下で寸法変化の起こり難い素材であり、使用時の摩耗も起こり難いものであり、良好な回転状態がより安定する。   In the rolling bearing for cryogenic environment according to the present invention, the inner ring and outer ring made of martensitic stainless steel or high-speed tool steel are materials that do not easily undergo dimensional changes at extremely low temperatures, and wear during use is also unlikely to occur. And a good rotation state is more stable.
また、内輪と外輪の回転時に摩擦接触する転動体は、樹脂成分が移着しやすいセラミックス製であるから、回転に伴って保持器から適当な頻度で移着する樹脂成分、特にポリテトラフルオロエチレン(PTFE)が極低温下でも安定して優れた固体潤滑性を発揮し、内輪と外輪が転動体に接触する度に、転動体が固体潤滑されて摩耗は抑制され、円滑に安定して回転する。   In addition, the rolling elements that are in frictional contact during rotation of the inner ring and the outer ring are made of ceramics in which the resin component is easily transferred. Therefore, the resin component that transfers at an appropriate frequency from the cage with rotation, particularly polytetrafluoroethylene. (PTFE) stably exhibits excellent solid lubricity even at extremely low temperatures, and every time the inner ring and outer ring come into contact with the rolling element, the rolling element is solid-lubricated to suppress wear and rotate smoothly and stably. To do.
そのため、転がり軸受を長期間使用するときにも軌道面および転動体の摩耗が極めて少なくなり、特にLNGによって潤滑されかつ冷却されるという極低温環境下での内外輪と転動体が長期使用に耐えるようになり、耐摩耗性および潤滑性が低下せず耐久性に優れた極低温環境用転がり軸受となる。   Therefore, even when the rolling bearing is used for a long period of time, the wear of the raceway surface and the rolling element is extremely reduced, and the inner and outer rings and the rolling element in an extremely low temperature environment that is lubricated and cooled by LNG can withstand long-term use. Thus, a rolling bearing for a cryogenic environment having excellent durability without deterioration in wear resistance and lubricity is obtained.
上記セラミックス製の転動体は、窒化ケイ素系のセラミックス製転動体であることが高硬度で耐摩耗性に優れているので、好ましい。
また、上記極低温環境用転がり軸受は、液化ガス用ポンプの転がり軸受に適用できる。液化ガス用ポンプである液化天然ガス用サブマージドポンプは、特にこの発明の転がり軸受の実用的利用価値を高める適用例である。
The ceramic rolling element is preferably a silicon nitride ceramic rolling element because of its high hardness and excellent wear resistance.
The rolling bearing for the cryogenic environment can be applied to a rolling bearing of a liquefied gas pump. The liquefied natural gas submerged pump, which is a liquefied gas pump, is an application example that increases the practical utility value of the rolling bearing of the present invention.
この発明は、セラミックス製転動体と、樹脂製保持器とを具備し、常温での所定の隙間比率C=(転動体径×案内隙間)/(内輪外径×ラジアル内部隙間)の特定された極低温環境用転がり軸受としたので、極低温下で固体潤滑剤を保持器からの接触で供給するための案内隙間や、ラジアル内部隙間について寸法変化が抑制され、回転不良を確実に防止でき、また軌道面および転動体の摩耗が極めて少ないものとなり、特にLNG等の液化ガスによって潤滑されかつ冷却される極低温環境下や宇宙環境のような極低温環境下でも長期間の使用に耐えて経時的に耐摩耗性および潤滑性が低下せず、回転状態の安定した極低温環境用転がり軸受になる利点がある。   The present invention includes a ceramic rolling element and a resin cage, and has a specified gap ratio C = (rolling body diameter × guide gap) / (inner ring outer diameter × radial inner gap) at room temperature. Because it is a rolling bearing for cryogenic environment, dimensional change is suppressed for the guide gap for supplying solid lubricant by contact from the cage at extremely low temperature and the radial internal gap, and rotation failure can be reliably prevented, In addition, the wear of the raceway surface and rolling elements is extremely small, and it can withstand long-term use even in a cryogenic environment such as LNG or a cryogenic environment that is lubricated and cooled by a liquefied gas such as LNG. In particular, the wear resistance and lubricity are not lowered, and there is an advantage that a rolling bearing for a cryogenic environment having a stable rotation state is obtained.
実施形態を示す極低温環境用転がり軸受の要部断面図Sectional drawing of the principal part of the rolling bearing for cryogenic environments which shows embodiment 実施形態の使用状態を説明し、液化天然ガス用サブマージドポンプの概略構成図Schematic diagram of a submerged pump for liquefied natural gas, explaining the state of use of the embodiment
この発明の実施形態を以下に添付図面に基づいて説明する。
図1に示すように実施形態の転がり軸受は、後記所定の鋼材からなる内輪1の外径面1aと外輪2の内径面2aの間に、複数の転動体(玉)3を回転自在に保持する保持器4を設けた玉軸受Aであり、転動体3はセラミックス製であり、保持器4はポリテトラフルオロエチレンを主成分とする樹脂素材からなり、隙間比率C=(転動体径×案内隙間σ1)/(内輪外径×ラジアル内部隙間σ)の式で示される所定の隙間比率Cが2.5〜4である極低温環境用転がり軸受である。
ここで前記式中の案内隙間σ1は常温(20℃)での内輪外径面1aと保持器4の内径面との隙間(mm)であり、ラジアル内部隙間σは極低温下(−196℃)での外輪内径面2aと転動体3の表面との隙間(mm)である。
Embodiments of the present invention will be described below with reference to the accompanying drawings.
As shown in FIG. 1, the rolling bearing of the embodiment holds a plurality of rolling elements (balls) 3 rotatably between an outer diameter surface 1 a of an inner ring 1 and an inner diameter surface 2 a of an outer ring 2, which will be described later. The rolling element 3 is made of ceramics, the cage 4 is made of a resin material mainly composed of polytetrafluoroethylene, and the clearance ratio C = (Rolling element diameter × guide). This is a rolling bearing for a cryogenic environment in which a predetermined gap ratio C expressed by the equation of gap σ 1 ) / (inner ring outer diameter × radial inner gap σ 2 ) is 2.5 to 4 .
Here, the guide gap σ 1 in the above formula is the gap (mm) between the inner ring outer diameter surface 1a and the inner diameter surface of the cage 4 at room temperature (20 ° C.), and the radial inner gap σ 2 is extremely low (− The clearance (mm) between the outer ring inner surface 2a and the surface of the rolling element 3 at 196 ° C.).
上記した内輪1および外輪2は、マルテンサイト系ステンレス鋼または高速度工具鋼であり、これらは硬質で耐摩耗性に優れた鋼材である。マルテンサイト系ステンレス鋼の例としては、SUS403、SUS420、SUS440Cなどが挙げられる。また、高速度工具鋼としては、米国鉄鋼協会AISI規格の高速度鋼M50、日本工業規格のSKH4等が挙げられる。   The inner ring 1 and the outer ring 2 described above are martensitic stainless steel or high-speed tool steel, and these are steel materials that are hard and have excellent wear resistance. Examples of martensitic stainless steel include SUS403, SUS420, and SUS440C. Examples of the high-speed tool steel include American Steel Association AISI standard high-speed steel M50, Japanese Industrial Standard SKH4, and the like.
なお、図示は省略したが、内輪1および外輪2の基材の表面側、少なくとも軌道面(または転走面とも別称される。)に、ビッカース硬度(Hv)1000〜4000程度のダイヤモンドライクカーボンを主体とする硬質皮膜を、基材に対し表面へ向けて段階的または連続的に硬度を高めた中間層を介して設けることによって、より耐摩耗性を高めた実施形態とすることもできる。   Although not shown, diamond-like carbon having a Vickers hardness (Hv) of about 1000 to 4000 is provided on the surface side of the base material of the inner ring 1 and the outer ring 2, at least on the raceway surface (or also called the rolling surface). By providing the main hard film through an intermediate layer whose hardness is increased stepwise or continuously toward the surface of the base material, an embodiment with higher wear resistance can be obtained.
この発明に用いる転動体3は、セラミックス製であり、セラミックスの種類は、特に限定されないが、窒化ケイ素系、ジルコニア系、炭化ケイ素系、アルミナ系の各系のセラミックスを調製することができるが、例えば窒化ケイ素系セラミックス製の転動体は、特に硬質で耐摩耗性に優れているので好ましい。   The rolling element 3 used in this invention is made of ceramics, and the type of ceramics is not particularly limited, but silicon nitride-based, zirconia-based, silicon carbide-based, and alumina-based ceramics can be prepared. For example, rolling elements made of silicon nitride ceramics are preferable because they are particularly hard and excellent in wear resistance.
この発明に用いる保持器4は、ポリテトラフルオロエチレン(PTFE)、ポリプロピレン、ポリスチレン、アクリロニトリルスチレン、アクリロニトリル−ブタジエン−スチレンプラスチック、ポリ三フッ化塩化エチレン、ポリカーボネート、ポリメチルメタクリレート、ポリアミド6、ポリアミド66、ポリスルホン、ポリフェニレンオキシド、フェノール樹脂、エポキシ樹脂、不飽和ポリエステル樹脂、ユリア樹脂、メラミン樹脂などを主成分とする樹脂素材が用いられる。特に良好な潤滑性を考慮した場合、ポリテトラフルオロエチレン(例えばNTN社製:ベアリーFL3000等)からなるものを採用する。このような樹脂素材は、極低温でも転動体の表面に固体潤滑剤を移着させ、良好かつ安定した固体潤滑性を発揮させるからである。   The cage 4 used in the present invention is made of polytetrafluoroethylene (PTFE), polypropylene, polystyrene, acrylonitrile styrene, acrylonitrile-butadiene-styrene plastic, polytrifluoroethylene chloride, polycarbonate, polymethyl methacrylate, polyamide 6, polyamide 66, A resin material mainly composed of polysulfone, polyphenylene oxide, phenol resin, epoxy resin, unsaturated polyester resin, urea resin, melamine resin or the like is used. In consideration of particularly good lubricity, one made of polytetrafluoroethylene (for example, NTN Corporation: BEAREE FL3000) is employed. This is because such a resin material transfers a solid lubricant to the surface of the rolling element even at an extremely low temperature and exhibits good and stable solid lubricity.
保持器4の形式(または形態)は、特に限定されるものではなく、周知の環状のものであり、例えば冠型タイプ、また円筒またはリング状の周方向にポケット穴を等間隔に形成した円環状タイプ、さらに環状の軸方向に二つ割り可能なものであって、これら分割された部品をピンで加締めて一体化可能なタイプであっても良い。   The type (or form) of the cage 4 is not particularly limited, and is a well-known annular type, for example, a crown type type, or a circular shape in which pocket holes are formed at equal intervals in the circumferential direction of a cylinder or a ring. An annular type or a type that can be divided into two in the annular axial direction, and can be integrated by crimping these divided parts with pins.
また、この発明においては、転がり軸受の種類(型式)は、ラジアル内部隙間を有するものであれば特に限定されるものではなく、例えば、深溝玉軸受または円筒ころ軸受の極低温環境用転がり軸受であっても良い。   In the present invention, the type (model) of the rolling bearing is not particularly limited as long as it has a radial internal clearance. For example, it is a rolling bearing for cryogenic environments such as a deep groove ball bearing or a cylindrical roller bearing. There may be.
そして、この発明の極低温環境用転がり軸受は、その具体的な用途を、液化ガス用ポンプ用の転がり軸受としたものでも良く、また人工衛星アンテナの支持や駆動装置に用いる転がり軸受であっても良い。   The rolling bearing for the cryogenic environment of the present invention may be a rolling bearing for a pump for a liquefied gas, the rolling bearing used for supporting or driving a satellite antenna. Also good.
転がり軸受の用途が液化ガス用ポンプである場合は、液化天然ガス(LNG)用サブマージドポンプであってもよいが、その場合には、転がり軸受が直接に極低温のLNGに接触するため、この発明の内外輪と転動体が長期間の使用に耐えて耐摩耗性および潤滑性の低下しない耐久性に優れた極低温環境用転がり軸受となる効果が顕著に現れる。   When the application of the rolling bearing is a pump for liquefied gas, it may be a submerged pump for liquefied natural gas (LNG), but in that case, since the rolling bearing directly contacts the cryogenic LNG, The inner and outer rings and rolling elements of the present invention have a remarkable effect of becoming a rolling bearing for a cryogenic environment excellent in durability that withstands long-term use and does not deteriorate wear resistance and lubricity.
図2に示すように、液化天然ガス(LNG)用サブマージドポンプは、ポンプ全体を液中に浸漬することにより、ポット(圧力容器)8内で気密性を発揮するものであり、ポンプ軸9は、モータ軸10に同軸上に一体に連結された構造である。   As shown in FIG. 2, the submerged pump for liquefied natural gas (LNG) exhibits airtightness in a pot (pressure vessel) 8 by immersing the entire pump in the liquid. Is a structure integrally connected to the motor shaft 10 coaxially.
ポット8は、LNGの吸込口11を外側に向けて開口しており、また外部配管(図示せず。)に通じる吐出口12を有している。ポット8内に装着されたモータ13は、外部電源によって回転するモータ軸10の上側と下側を、図1に示される実施形態の玉軸受Aで支持しており、このモータ軸10と一体に回転するポンプ軸9には、複数段の羽根車(インペラー)14が取り付けられている。   The pot 8 is opened with the LNG suction port 11 facing outward, and has a discharge port 12 leading to an external pipe (not shown). The motor 13 mounted in the pot 8 supports the upper and lower sides of the motor shaft 10 rotated by an external power source with the ball bearing A of the embodiment shown in FIG. A plurality of stages of impellers 14 are attached to the rotating pump shaft 9.
このポンプの図示した装置内の流路は、駆動したモータ13によるポンプ軸9と一体に回転する羽根車14によって、ポット8内に吸込口11から流入したLNGが、ポット8の内側面に沿って下向きに流れ、多段の羽根車14の最下段部分から吸い込まれて、羽根車14の周囲に配置された筒状内壁15の内側の配管16から吐出口12に流れるが、LNGの一部は筒状内壁15の内側の他の配管17からモータ13内を潤滑液として流れて、玉軸受Aを潤滑および冷却し、ポット8の内側面に沿って下向きの流れに合流して、再度、多段の羽根車14の先端部分から吸い込まれる。   The flow path in the illustrated apparatus of the pump is such that the LNG flowing from the suction port 11 into the pot 8 along the inner surface of the pot 8 by the impeller 14 that rotates integrally with the pump shaft 9 by the driven motor 13. It flows downward and flows into the discharge port 12 from the pipe 16 inside the cylindrical inner wall 15 arranged around the impeller 14, and is sucked in from the lowermost portion of the multistage impeller 14. The other pipe 17 inside the cylindrical inner wall 15 flows in the motor 13 as a lubricating liquid, lubricates and cools the ball bearing A, joins the downward flow along the inner side surface of the pot 8, and again multistage. Is sucked from the tip of the impeller 14.
このようにして使用される玉軸受Aは、転動体を樹脂製保持器で保持し、転動体は、セラミックス製の転動体であり、前記保持器はポリテトラフルオロエチレンを主成分とする樹脂素材からなり、以下の式で示される所定の隙間比率Cが2.5〜4であるので、極低温下で固体潤滑剤を保持器からの接触で供給するための案内隙間や、ラジアル内部隙間について寸法変化が抑制され、回転不良を確実に防止できる。
これにより軌道面および転動体の摩耗が極めて少ないものとなり、特にLNG等の液化ガスによって潤滑されかつ冷却される極低温環境下や宇宙環境のような極低温環境下でも長期間の使用に耐えて経時的に耐摩耗性および潤滑性の低下せず、回転状態の安定した極低温環境用転がり軸受になる。
The ball bearing A used in this way holds the rolling element with a resin cage, the rolling element is a ceramic rolling element, and the cage is a resin material mainly composed of polytetrafluoroethylene. Since the predetermined gap ratio C expressed by the following formula is 2.5 to 4, the guide gap for supplying the solid lubricant by contact from the cage at a cryogenic temperature, and the radial internal gap Dimensional change is suppressed, and rotation failure can be reliably prevented.
As a result, the wear of the raceway surface and rolling elements becomes extremely low, and it can withstand long-term use even in a cryogenic environment such as a space environment or a cryogenic environment that is lubricated and cooled by a liquefied gas such as LNG. It becomes a rolling bearing for a cryogenic environment where the wear resistance and lubricity do not deteriorate with time and the rotational state is stable.
なお、上記したように、この発明の実施形態として、極低温環境用転がり軸受を示したが、前記した式で示される隙間比率Cが2.5〜4となるように、所定内径の外輪を選択してラジアル内部隙間を調整することを特徴とする極低温環境用転がり軸受の軸受内部隙間の調整方法の発明とすることもできる。   As described above, a rolling bearing for a cryogenic environment is shown as an embodiment of the present invention. However, an outer ring having a predetermined inner diameter is set so that the clearance ratio C represented by the above-described formula is 2.5 to 4. The invention may be an invention of a method for adjusting a bearing internal clearance of a rolling bearing for a cryogenic environment characterized by selecting and adjusting the radial internal clearance.
[実施例1〜3]
マルテンサイト系ステンレス鋼(SUS440C)の内輪と外輪を備え、窒化ケイ素系のセラミックス製の玉を転動体とし、ポリテトラフルオロエチレン(PTFE)を主成分とするNTN精密樹脂株式会社製のベアリーFL製の円環状の保持器を用いて、表1に示す型番の転がり軸受を組み立てた。
[Examples 1 to 3]
Made by BEAREE FL made by NTN Precision Resin Co., Ltd., which has martensitic stainless steel (SUS440C) inner and outer rings, with silicon nitride ceramic balls as rolling elements and polytetrafluoroethylene (PTFE) as the main component The rolling bearings of the model numbers shown in Table 1 were assembled using an annular cage.
表1中にNTN社製の各種転がり(玉)軸受の型番と、その内輪内径φd(mm)と外輪外径φD(mm)を示すと共に、常温(20℃)での玉径(mm)と案内隙間σ1(mm)(=内輪外径面と保持器内径面との隙間幅)との積:C1を示し、また常温(20℃)での内輪外径(mm)とラジアル内部隙間σ(mm)(=外輪軌道面と転動体表面との隙間幅)との積:Cを示し、また隙間比率C=C/Cの値を表1中に示した。
また、実施例1〜3の転がり軸受を極低温下(−196℃)の環境下における玉径(mm)と案内隙間σ1(mm)(=内輪外径面と保持器内径面との隙間幅)とを調べ、それらの積C1を表中に併記した。
Table 1 shows the model numbers of various rolling (ball) bearings manufactured by NTN, the inner ring inner diameter φd (mm) and the outer ring outer diameter φD (mm), and the ball diameter (mm) at room temperature (20 ° C.). Product of guide clearance σ 1 (mm) (= clearance width between inner ring outer diameter surface and cage inner diameter surface): C 1 , inner ring outer diameter (mm) at normal temperature (20 ° C) and radial inner clearance The product of σ 2 (mm) (= the gap width between the outer ring raceway surface and the rolling element surface): C 2 is shown, and the value of the gap ratio C = C 1 / C 2 is shown in Table 1.
Further, in the rolling bearings of Examples 1 to 3, the ball diameter (mm) and the guide clearance σ 1 (mm) (= the clearance between the inner ring outer diameter surface and the cage inner diameter surface) in an environment at an extremely low temperature (−196 ° C.). Width) and their product C 1 is also shown in the table.
[比較例1〜3]
上記各実施例と同じ型番の転がり(玉)軸受と同じ素材からなる部品を組み立てて、表1に示す内輪内径φd(mm)と外輪外径φD(mm)の転がり軸受を製造し、常温(20℃)環境下において所定範囲(2.5〜4)の範囲外の隙間比率C=C/Cに設定し、これらの軸受についても実施例と同様に各寸法を調べ、常温(20℃)での玉径(mm)と案内隙間σ1(mm)との積:C1、および常温(20℃)での内輪外径(mm)とラジアル内部隙間σ(mm)との積:Cを表1中に示した。
また、比較例1〜3の転がり軸受を極低温下(−196℃)の環境下において、玉径(mm)と案内隙間σ1(mm)(=内輪外径面と保持器内径面との隙間幅)とを調べ、それらの積C1を表中に併記した。
[Comparative Examples 1-3]
Assembling the parts made of the same material as the rolling (ball) bearing of the same model number as in each of the above embodiments, the rolling bearings having the inner ring inner diameter φd (mm) and the outer ring outer diameter φD (mm) shown in Table 1 are manufactured. (20 ° C.) In the environment, the clearance ratio C = C 1 / C 2 outside the predetermined range (2.5 to 4) is set. Product of ball diameter (mm) and guide clearance σ 1 (mm) at ° C): product of C 1 and inner ring outer diameter (mm) at normal temperature (20 ° C) and radial internal clearance σ 2 (mm) : showed C 2 in Table 1.
Further, in the rolling bearings of Comparative Examples 1 to 3 in an environment at an extremely low temperature (−196 ° C.), the ball diameter (mm) and the guide clearance σ 1 (mm) (= the outer diameter surface of the inner ring and the inner diameter surface of the cage) And the product C 1 is also shown in the table.
表1の結果からも明らかなように、隙間比率C=C1/Cの値が、2.5未満の比較例1、2は、適正な案内隙間の1/2以下(比較例1)であり、また玉径×案内隙間の値がマイナスの値で圧接状態を示しており(比較例2)、保持器は内輪に接触して回転不良または発熱する状態になった。また、隙間比率Cが4.5の比較例3は、保持器は転がり軸受内部で遊動し、いわゆるガタつきと振動を起こして回転不良の状態であった。 As is clear from the results of Table 1, Comparative Examples 1 and 2 in which the value of the gap ratio C = C 1 / C 2 is less than 2.5 is 1/2 or less of the appropriate guide gap (Comparative Example 1). In addition, the value of the ball diameter × guide gap is a negative value, indicating a pressure contact state (Comparative Example 2), and the cage comes into contact with the inner ring and is in a state of poor rotation or heat generation. Further, in Comparative Example 3 in which the gap ratio C is 4.5, the cage is loosely moved inside the rolling bearing, causing a so-called rattling and vibration, resulting in poor rotation.
一方、隙間比率Cが、2.7〜3.6の実施例1〜3は、いずれも回転状態が円滑であり、極低温環境下でも長期間の使用に耐え、経時的に耐摩耗性および潤滑性が低下せずに安定した回転状態であった。   On the other hand, each of Examples 1 to 3 having a gap ratio C of 2.7 to 3.6 has a smooth rotation state, can withstand long-term use even in a cryogenic environment, and is resistant to wear over time. It was in a stable rotational state without lowering the lubricity.
1 内輪
1a 内輪外径面
2 外輪
2a 外輪内径面
3 転動体
4 保持器
8 ポット
9 ポンプ軸
10 モータ軸
11 吸込口
12 吐出口
13 モータ
14 羽根車
15 筒状内壁
16、17 配管
DESCRIPTION OF SYMBOLS 1 Inner ring 1a Inner ring outer diameter surface 2 Outer ring 2a Outer ring inner diameter surface 3 Rolling body 4 Cage 8 Pot 9 Pump shaft 10 Motor shaft 11 Suction port 12 Discharge port 13 Motor 14 Impeller 15 Cylindrical inner walls 16, 17 Piping

Claims (5)

  1. マルテンサイト系ステンレス鋼または高速度工具鋼からなる内・外輪の内・外径面間に、複数の転動体を回転自在に保持する保持器を設けた転がり軸受において、
    前記転動体は、セラミックス製の転動体であり、前記保持器は樹脂素材からなり、以下の式で示される20℃の隙間比率Cが2.5〜4であることを特徴とする極低温環境用転がり軸受。
    隙間比率C=(転動体径×案内隙間)/(内輪外径×ラジアル内部隙間)
    (上記式中、案内隙間=内輪外径面と保持器内径面との隙間幅であり、ラジアル内部隙間=外輪軌道面と転動体表面との隙間幅である。)
    In rolling bearings with cages that hold multiple rolling elements in a rotatable manner between the inner and outer diameter surfaces of inner and outer rings made of martensitic stainless steel or high-speed tool steel,
    The rolling element is a ceramic rolling element, the cage is made of a resin material, and a 20 ° C. gap ratio C expressed by the following formula is 2.5 to 4; Rolling bearing for use.
    Clearance ratio C = (Rolling element diameter × Guide clearance) / (Inner ring outer diameter × Radial internal clearance)
    (In the above formula, the guide gap is the gap width between the inner ring outer diameter surface and the cage inner diameter surface, and the radial inner gap is the gap width between the outer ring raceway surface and the rolling element surface.)
  2. 上記転動体が、窒化ケイ素系のセラミックス製転動体である請求項1に記載の極低温環境用転がり軸受。   The rolling bearing for a cryogenic environment according to claim 1, wherein the rolling element is a silicon nitride ceramic rolling element.
  3. 上記保持器が、ポリテトラフルオロエチレンを主成分とする樹脂素材からなる樹脂製保持器である請求項1または2に記載の極低温環境用転がり軸受。   The rolling bearing for a cryogenic environment according to claim 1 or 2, wherein the cage is a resin cage made of a resin material having polytetrafluoroethylene as a main component.
  4. 上記極低温環境用転がり軸受が、液化ガス用ポンプの転がり軸受である請求項1〜3のいずれかに記載の極低温環境用転がり軸受。   The rolling bearing for cryogenic environment according to any one of claims 1 to 3, wherein the rolling bearing for cryogenic environment is a rolling bearing of a pump for liquefied gas.
  5. 上記液化ガス用ポンプが、液化天然ガス用サブマージドポンプである請求項4に記載の極低温環境用転がり軸受。   The rolling bearing for a cryogenic environment according to claim 4, wherein the liquefied gas pump is a submerged pump for liquefied natural gas.
JP2016034422A 2016-02-25 2016-02-25 Roller bearing for cryogenic environment Pending JP2017150593A (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3460246A1 (en) * 2017-09-19 2019-03-27 Fives Cryomec AG Centrifugal pump for cryogenic feed media
WO2020050020A1 (en) * 2018-09-04 2020-03-12 日立ジョンソンコントロールズ空調株式会社 Electric compressor, and refrigeration and air conditioning device using same

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2006224816A (en) * 2005-02-17 2006-08-31 Nsk Ltd Column assist type electric power steering device
JP5750901B2 (en) * 2011-01-19 2015-07-22 日本精工株式会社 Rolling bearing
JP2015096768A (en) * 2013-10-09 2015-05-21 日本精工株式会社 Cage and rolling bearing, and pump for liquefied gas

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3460246A1 (en) * 2017-09-19 2019-03-27 Fives Cryomec AG Centrifugal pump for cryogenic feed media
WO2020050020A1 (en) * 2018-09-04 2020-03-12 日立ジョンソンコントロールズ空調株式会社 Electric compressor, and refrigeration and air conditioning device using same

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