JP2013204645A - Gear excellent in tooth surface fatigue damage life - Google Patents
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- JP2013204645A JP2013204645A JP2012072296A JP2012072296A JP2013204645A JP 2013204645 A JP2013204645 A JP 2013204645A JP 2012072296 A JP2012072296 A JP 2012072296A JP 2012072296 A JP2012072296 A JP 2012072296A JP 2013204645 A JP2013204645 A JP 2013204645A
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本発明は、自動車用変速機をはじめとした各種伝達装置、或はＣＶＴプーリー等の動力伝達部品へ適用する歯車に関するものであり、特に優れた歯面疲労損傷寿命を発揮する様な歯車に関するものである。 The present invention relates to a gear applied to various transmission devices such as a transmission for an automobile or a power transmission component such as a CVT pulley, and particularly to a gear that exhibits a superior tooth surface fatigue damage life. It is.
自動車用変速機等で用いられる歯車は、高い接触面圧で使用されることから、ピッチング（ｐｉｔｔｉｎｇ）やスコーリング（ｓｃｏｒｉｎｇ）等の歯面の疲労損傷（剥離損傷）が生じることがある。特に近年では、燃費向上を目的としてユニットの小型化によって歯車も小型化しており、歯車の単位面積に加わる負荷が増大し、これによって歯車表面の摩擦力が増大して歯車表面の温度が上昇しやすくなっており、歯面疲労損傷が生じやすい状況である。歯面疲労損傷は、歯車の寿命を縮めることになるので、歯面疲労損傷に対する耐性（これを「歯面疲労損傷寿命」と呼ぶ）に優れていることは、歯車において重要な要求特性である。 Since gears used in automobile transmissions and the like are used with high contact surface pressure, tooth surface fatigue damage (peeling damage) such as pitching and scoring may occur. Particularly in recent years, gears have also been downsized due to the downsizing of the unit for the purpose of improving fuel efficiency, increasing the load applied to the unit area of the gear, which increases the frictional force on the gear surface and increases the temperature of the gear surface. This is a situation where tooth surface fatigue damage is likely to occur. Since tooth surface fatigue damage shortens the life of gears, it is an important requirement for gears to have excellent resistance to tooth surface fatigue damage (this is called "tooth surface fatigue life"). .
歯面疲労損傷寿命を向上させる技術としては、焼戻し軟化抵抗性を向上させ、高温硬さを高めることが行われている。しかしながら、歯車の高温硬さを高くすると、歯面間の馴染み性が低下し、歯面での応力緩和が起こり難くなり、却って歯面疲労損傷寿命が低下することになる。 As a technique for improving the tooth surface fatigue damage life, temper softening resistance is improved and high temperature hardness is increased. However, when the high-temperature hardness of the gear is increased, the conformability between the tooth surfaces decreases, stress relaxation on the tooth surfaces hardly occurs, and on the contrary, the tooth surface fatigue damage life decreases.
一方、リン酸マンガン処理等の化成処理（化学研磨）を施し、歯車表面の摩擦力を低減する潤滑処理が行われている。このような化成処理を施すことによって、歯車表面に加わる摩擦力が低減され、歯面疲労損傷寿命が向上することが期待される。しかしながら、歯車の単位面積に加わる負荷が増大しており、化成処理を施しても十分な歯面疲労損傷寿命が得られない場合がある。 On the other hand, chemical conversion treatment (chemical polishing) such as manganese phosphate treatment is performed, and a lubrication treatment is performed to reduce the frictional force on the gear surface. By performing such chemical conversion treatment, it is expected that the frictional force applied to the gear surface is reduced and the tooth surface fatigue damage life is improved. However, the load applied to the unit area of the gear is increasing, and even if a chemical conversion treatment is performed, a sufficient tooth surface fatigue damage life may not be obtained.
歯面疲労損傷寿命を向上させるための技術としてこれまでにも様々提案されている。例えば特許文献１には、リン酸塩処理にて潤滑性を確保すると共に、焼戻し軟化抵抗性を高めるために、鋼材中のＳｉ，ＣｒおよびＭｏの含有量を適切に規定することが提案されている。しかしながら、鋼材の化学成分組成を調整するだけでは、歯面疲労損傷寿命を向上させることには限度がある。
Various techniques have been proposed so far for improving the tooth surface fatigue damage life. For example,
また特許文献２には、歯車表面に凹部を設け、この凹部にリン酸マンガン粒子を残留させることによって、歯車の潤滑性を向上させる金属表面処理方法が提案されている。更に、特許文献３では、リン酸塩処理、化学研磨、電解研磨等による歯車の歯面粗さの片寄りを制御することによって、歯面疲労強度を向上させることが提案されている。しかしながら、これらの技術においても、近年要求されるような十分な歯面疲労損傷寿命が得られない場合がある。
本発明はこの様な事情に鑑みてなされたものであって、その目的は、優れた歯面疲労損傷寿命を発揮して近年の要求特性に十分に対応できる様な歯車を提供することにある。 The present invention has been made in view of such circumstances, and an object of the present invention is to provide a gear that exhibits an excellent tooth surface fatigue damage life and can sufficiently cope with recent required characteristics. .
上記課題を解決することのできた本発明の歯車とは、歯車素地表面に凹部形状が存在する表面性状において、ＪＩＳ Ｂ ０６７１−２に規定される突出山部断面積Ａ１（μｍ2）と、突出谷部断面積Ａ２（μｍ2）の比（Ａ２／Ａ１）が３〜１１．０であると共に、ＪＩＳ Ｂ ０６０１に規定される粗さ曲線の最大谷深さＲｖが１０．０μｍ以下である点に要旨を有するものである。 The gear of the present invention that has been able to solve the above-mentioned problems includes a protruding mountain cross-sectional area A1 (μm 2 ) defined in JIS B 0671-2 and a protruding surface in a surface property in which a concave shape exists on the surface of the gear base. The ratio (A2 / A1) of the valley cross-sectional area A2 (μm 2 ) is 3 to 11.0, and the maximum valley depth Rv of the roughness curve defined in JIS B 0601 is 10.0 μm or less It has a gist.
本発明の歯車においては、歯車素地表面に存在する凹部における開口径の平均値が、１６〜３０μｍであることが好ましい。 In the gear of this invention, it is preferable that the average value of the opening diameter in the recessed part which exists in the gear base | substrate surface is 16-30 micrometers.
本発明は上記のように構成されており、歯車素地表面に凹部を存在させると共に、その表面性状を適正に制御することによって、歯面の強度を維持しつつ潤滑油保持機能を向上させ、歯面疲労損傷寿命を飛躍的に向上させることができた。 The present invention is configured as described above, and has a concave portion on the surface of the gear base and appropriately controls the surface properties to improve the lubricating oil retaining function while maintaining the tooth surface strength. The surface fatigue damage life could be drastically improved.
本発明者らは、歯車における歯面疲労損傷寿命を向上させるべく、様々な角度から検討した。その結果、仕上げ加工後に適切な条件で酸洗し、歯車素地表面における表面性状を適切に制御してやれば、歯面の基本的な強度を維持しつつ潤滑油保持機能を向上させることができ、これによって歯面疲労損傷寿命を飛躍的に向上させることができることを見出し、本発明を完成した。 The present inventors have studied from various angles in order to improve the tooth surface fatigue damage life of the gear. As a result, it is possible to improve the lubricating oil retention function while maintaining the basic strength of the tooth surface by pickling under appropriate conditions after finishing and appropriately controlling the surface properties on the surface of the gear base. It has been found that the tooth surface fatigue damage life can be drastically improved, and the present invention has been completed.
歯面疲労損傷寿命を向上させるためには、相対する歯車歯面間の金属接触を防ぐ潤滑油膜の形成を助長させるような、潤滑油保持機能を高めた表面形状であることが必要であり、そのためには、歯面に深い凹部形状を形成することが有効である。また、従来のリン酸塩処理等の化学研磨や通常の酸洗処理では、歯車素地の表面にある程度の凹部が存在する状態とはなるが、潤滑油保持機能（以下、「油留り性」と呼ぶことがある）を高め得るような形態にはならないのが実状である。また、凹凸形状が大きくなり過ぎたり、凹部の深さが深くなり過ぎたりすると、歯面強度が低下し、歯面疲労損傷寿命が却って低下することも考慮する必要がある。 In order to improve the tooth surface fatigue damage life, it is necessary to have a surface shape with an enhanced lubricating oil retention function that promotes the formation of a lubricating oil film that prevents metal contact between the gear tooth surfaces facing each other, For this purpose, it is effective to form a deep concave shape on the tooth surface. In addition, in conventional chemical polishing such as phosphate treatment and normal pickling treatment, a certain degree of recesses are present on the surface of the gear base, but a lubricating oil retaining function (hereinafter referred to as “oil retention”). The actual situation is that it does not become a form that can be improved. In addition, it is necessary to consider that if the uneven shape becomes too large or the depth of the recessed portion becomes too deep, the tooth surface strength decreases and the tooth surface fatigue damage life decreases.
こうした着想に基づき、歯車素地表面の表面性状を適正化する指標として、ＪＩＳ Ｂ ０６７１−２（２００２）に規定される突出山部断面積Ａ１（μｍ2）と突出谷部断面積Ａ２（μｍ2）との比（Ａ２／Ａ１）、およびＪＩＳ Ｂ ０６０１（２００１）に規定される粗さ曲線の最大谷深さＲｖを選び、これらを適切な範囲に規定したものである。これらの基本的な概念、および範囲設定理由は次の通りである。 Based on such an idea, as an index for optimizing the surface properties of the gear substrate surface, the protruding peak section A1 (μm 2 ) and the protruding valley section A2 (μm 2 ) defined in JIS B 0671-2 (2002) are used. ) (A2 / A1) and the maximum valley depth Rv of the roughness curve defined in JIS B 0601 (2001), and these are defined in an appropriate range. The basic concept and the reason for setting the range are as follows.
突出山部断面積Ａ１と突出谷部断面積Ａ２は、ＪＩＳ Ｂ ０６７１−２（２００２）に規定される概念であり、下記のようにして求められる。 The protruding peak section A1 and the protruding valley section A2 are concepts defined in JIS B 0671-2 (2002), and are obtained as follows.
突出山部断面積Ａ１と突出谷部断面積Ａ２は、ＪＩＳ Ｂ ０６７１−２（２００２）基づき、図１に示す負荷曲線から求められる。具体的には、負荷曲線上で、負荷長さ率Ｍｒが４０％となるような２点（Ａ，Ｂ）を通る直線の中で、傾きが最も小さい直線を求め、この直線とＭｒ＝０％、Ｍｒ＝１００％との交点を夫々点Ｃ、点Ｄとする。この点Ｃを通る切断レベルと負荷曲線との交点をＨ、Ｍｒ＝０％との交点をＩとしたとき、線分ＣＨ、線分ＣＩ、曲線ＨＩで囲まれる面積が突出山部断面積Ａ１である。また点Ｄを通る切断レベルと負荷曲線との交点をＥとし、Ｍｒ＝１００％との交点をＦとしたとき、線分ＤＥ、線分ＤＦ、曲線ＥＦで囲まれる面積が突出谷部断面積Ａ２である。尚、本発明では、突出山部断面積Ａ１と突出谷部断面積Ａ２は、評価長さ：４ｍｍ、カットオフ：０．８ｍｍ、５区間の条件で求めた。 The protruding peak section A1 and the protruding valley section A2 are obtained from the load curve shown in FIG. 1 based on JIS B 0671-2 (2002). Specifically, a straight line having the smallest inclination is obtained from straight lines passing through two points (A, B) such that the load length ratio Mr is 40% on the load curve, and this straight line and Mr = 0. % And Mr = 100% are point C and point D, respectively. When the intersection of the cutting level passing through the point C and the load curve is H, and the intersection of Mr = 0% is I, the area enclosed by the line segment CH, the line segment CI, and the curve HI is the protruding peak cross-sectional area A1. It is. When the intersection between the cutting level passing through the point D and the load curve is E, and the intersection with Mr = 100% is F, the area surrounded by the line segment DE, the line segment DF, and the curve EF is the projecting valley cross-sectional area. A2. In the present invention, the protruding peak portion cross-sectional area A1 and the protruding valley portion cross-sectional area A2 were obtained under the conditions of evaluation length: 4 mm, cutoff: 0.8 mm, and five sections.
本発明の歯車では、歯車素地の表面性状において、上記のようにして求められる突出山部断面積Ａ１（μｍ2）と突出谷部断面積Ａ２（μｍ2）の比（Ａ２／Ａ１）が３〜１１．０であることが必要である。この比（Ａ２／Ａ１）の値が３未満になると、歯車素地表面の凹部での油留り性が低下して歯面疲労損傷寿命の向上効果が発揮されない。また比（Ａ２／Ａ１）の値が１１．０を超えると、歯車素地表面の凹部の量が大きくなり過ぎ、歯面が脆くなり、歯面疲労損傷寿命が低下する。比（Ａ２／Ａ１）の値の好ましい下限は３．５以上（より好ましくは４．０以上）であり、好ましい上限は１０．５以下（より好ましくは１０．０以下）である。 In the gear according to the present invention, the ratio (A2 / A1) of the protruding peak cross-sectional area A1 (μm 2 ) to the protruding valley cross-sectional area A2 (μm 2 ) obtained as described above is 3 in the surface texture of the gear base. It must be ˜11.0. When the value of this ratio (A2 / A1) is less than 3, the oil retention in the recesses on the surface of the gear base is lowered, and the effect of improving the tooth surface fatigue damage life is not exhibited. On the other hand, if the ratio (A2 / A1) exceeds 11.0, the amount of recesses on the surface of the gear base becomes too large, the tooth surface becomes brittle, and the tooth surface fatigue damage life decreases. The preferable lower limit of the value of the ratio (A2 / A1) is 3.5 or more (more preferably 4.0 or more), and the preferable upper limit is 10.5 or less (more preferably 10.0 or less).
一方、粗さ曲線の最大谷深さＲｖは、ＪＩＳ Ｂ ０６０１（２００１）に規定されるものであり、粗さ曲線の最大深さを表したものである。この最大谷深さＲｖは、粗さ曲線を基準長さ毎に区切り（例えば、５区間）、各基準長さにおいて、平均線から谷底までの深さをＲｖｉとしたときに、各基準長さにおいて求めたＲｖｉの深さの最大値が最大谷深さＲｖである。尚、本発明では、最大谷深さＲｖは、評価長さ：４ｍｍ、カットオフ：０．８ｍｍ、５区間の条件で求めた。 On the other hand, the maximum valley depth Rv of the roughness curve is defined in JIS B 0601 (2001) and represents the maximum depth of the roughness curve. The maximum valley depth Rv is obtained by dividing the roughness curve into reference lengths (for example, five sections), and for each reference length, the depth from the average line to the valley bottom is Rvi. The maximum value of the depth of Rvi obtained in the above is the maximum valley depth Rv. In the present invention, the maximum valley depth Rv was obtained under the conditions of evaluation length: 4 mm, cut-off: 0.8 mm, and 5 sections.
最大谷深さＲｖの平均値が１０．０μｍよりも大きくなると、凹部が歯面疲労損傷の起点となり、歯面疲労損傷寿命が低下することになる。最大谷深さＲｖの平均値は好ましくは９．０μｍ以下（より好ましくは８．０μｍ以下）である。最大谷深さＲｖの平均値の下限は特に限定されないが、例えば０．５μｍ程度である。 When the average value of the maximum valley depth Rv is larger than 10.0 μm, the concave portion becomes the starting point of tooth surface fatigue damage, and the tooth surface fatigue damage life is reduced. The average value of the maximum valley depth Rv is preferably 9.0 μm or less (more preferably 8.0 μm or less). The lower limit of the average value of the maximum valley depth Rv is not particularly limited, but is, for example, about 0.5 μm.
本発明の歯車においては、歯車素地表面に存在する凹部における開口径の平均値（平均開口径）が、１６〜３０μｍであることが好ましい。平均開口径が１６μｍ未満では、歯車素地表面の凹部の油溜り性が小さくなり、歯車疲労強度が向上しない。平均開口径が３０μｍを超えると、歯車素地表面の凹部が大きくなり、凹部が歯面疲労損傷の起点となるため歯面疲労損傷寿命が低下する傾向を示す。平均開口径の好ましい下限は１８μｍ以上であり（より好ましくは２０μｍ以上）、好ましい上限は２８μｍ以下（より好ましくは２６μｍ以下）である。尚、凹部における開口径とは、凹部における摺動方向の幅と摺動方向に垂直な方向の幅との平均値である。 In the gear of this invention, it is preferable that the average value (average opening diameter) of the opening diameter in the recessed part which exists in the gear base | substrate surface is 16-30 micrometers. When the average opening diameter is less than 16 μm, the oil retention of the recesses on the surface of the gear base is reduced, and the gear fatigue strength is not improved. When the average opening diameter exceeds 30 μm, the concave portion of the surface of the gear base becomes large, and the concave portion becomes a starting point of tooth surface fatigue damage, so that the tooth surface fatigue damage life tends to be reduced. The preferable lower limit of the average opening diameter is 18 μm or more (more preferably 20 μm or more), and the preferable upper limit is 28 μm or less (more preferably 26 μm or less). In addition, the opening diameter in a recessed part is an average value of the width | variety of the sliding direction in a recessed part, and the width | variety perpendicular to a sliding direction.
上記のような歯車素地表面の表面性状は、リン酸塩処理等の化学研磨を施しては実現できず、化学研磨する代わりに特定の条件で酸洗処理する必要がある。即ち、圧延材に対して、粗加工を施した後、浸炭処理および仕上げ加工を施し、その後にリン酸塩処理等の化学研磨を施す代わりに、所定の条件で酸洗処理する必要がある。このときの酸洗条件としては、用いる鋼種によっても若干異なるが、濃度が１５〜３５％程度（好ましくは２０〜３０％程度）の硫酸水溶液を用い、水溶液温度３０〜９０℃程度（好ましくは４０〜８０℃程度、より好ましくは５０〜７０℃程度）として３〜７５分程度（好ましくは５〜６０分程度、より好ましくは１０〜５０分程度）の浸漬処理を行う必要がある。 The surface texture of the surface of the gear base as described above cannot be realized by performing chemical polishing such as phosphating, and needs to be pickled under specific conditions instead of chemical polishing. That is, instead of subjecting the rolled material to roughing, then carburizing and finishing, and then performing chemical polishing such as phosphate treatment, it is necessary to perform pickling treatment under predetermined conditions. The pickling conditions at this time are slightly different depending on the steel type to be used, but an aqueous sulfuric acid solution having a concentration of about 15 to 35% (preferably about 20 to 30%) is used, and the aqueous solution temperature is about 30 to 90 ° C. (preferably 40). It is necessary to perform immersion treatment for about 3 to 75 minutes (preferably about 5 to 60 minutes, more preferably about 10 to 50 minutes) as about -80 ° C, more preferably about 50-70 ° C.
本発明で用いる鋼材としては、歯車用に用いられている通常のものであればよく、例えばＪＩＳに規定されているＳ３５Ｃ、Ｃ４５Ｃ等の機械構造用炭素鋼や、ＳＣｒ４２０、ＳＣｒ４２０Ｈ、ＳＣＭ４２０、ＳＮＣ４１５、ＳＮＣＭ４２０等の機械構造用合金鋼等が挙げられる。 The steel material used in the present invention may be any ordinary steel material used for gears. For example, carbon steel for mechanical structures such as S35C and C45C defined in JIS, SCr420, SCr420H, SCM420, SNC415, Examples thereof include alloy steel for machine structure such as SNCM420.
以下、実施例によって本発明をより具体的に説明するが、本発明はもとより下記実施例によって制限を受けるものではなく、前・後記の趣旨に適合し得る範囲で変更を加えて実施することは勿論可能であり、それらはいずれも本発明の技術的範囲に包含される。 Hereinafter, the present invention will be described in more detail by way of examples.However, the present invention is not limited by the following examples as a matter of course, and may be implemented with modifications within a range that can meet the gist of the preceding and following descriptions. Of course, they are all possible and are included in the technical scope of the present invention.
ＪＩＳ ＳＣｒ４２０Ｈ相当鋼の圧延材を、所定の形状に粗加工した後、浸炭処理を行った後、仕上げ加工を行い、図２に示す試験片形状（ローラーピッチング試験片形状）に加工し、試験片とした。尚、このときの浸炭処理は、９３０℃にてカーボンポテンシャル（Ｃｐ）が０．８％、有効浸炭深さ（ＥＣＤ）が１．０ｍｍとなるようにし、その後、焼戻し１７０℃×２時間を行った。 A JIS SCr420H equivalent steel rolled material is roughly processed into a predetermined shape, then carburized, and then finished, and processed into a test piece shape (roller pitching test piece shape) shown in FIG. It was. In this case, the carburization treatment is performed such that the carbon potential (Cp) is 0.8% and the effective carburization depth (ECD) is 1.0 mm at 930 ° C., and then tempering is performed at 170 ° C. × 2 hours. It was.
上記で得られた試験片に対し、下記表１に示す各種の潤滑処理（化成処理、酸洗処理）を施した。尚、酸洗する試験片については、酸洗前の表面粗さが粗いと凹部が生成されにくいため、上記仕上げ加工では通常の歯車の研磨品と同等となるように、算術平均粗さＲａで０．１〜０．４μｍとなるように研磨処理を施した。この研磨後、硫酸や塩酸等を用いて酸洗を実施し、試験片の摺動面（試験片の試験面）に凹部を生成した。下記表１には、酸洗条件を示した。 The test pieces obtained above were subjected to various lubricating treatments (chemical conversion treatment, pickling treatment) shown in Table 1 below. In addition, for the test piece to be pickled, since the concave portion is difficult to be generated if the surface roughness before pickling is rough, the arithmetic average roughness Ra is equal to that of a normal gear polished product in the above finishing process. Polishing processing was performed so that it might be set to 0.1-0.4 micrometer. After this polishing, pickling was performed using sulfuric acid, hydrochloric acid or the like, and a recess was formed on the sliding surface of the test piece (the test surface of the test piece). Table 1 below shows pickling conditions.
上記の処理を施した各試験片について、表面性状（Ｒｖ、Ａ２、Ａ１、Ａ２／Ａ１、平均開口径）を下記の方法で測定すると共に、ローラーピッチング試験によって、歯面疲労損傷寿命を測定した。 About each test piece which performed said process, while measuring surface property (Rv, A2, A1, A2 / A1, average opening diameter) by the following method, the tooth surface fatigue damage life was measured by the roller pitching test. .
[表面性状の測定]
ミツトヨ社製「ＣＳ３２００」にて、図２に示す試験片の円周上９０°ごと４箇所で、評価長さ：４ｍｍ、カットオフ：０．８ｍｍ、５区間の条件にて、ＪＩＳ Ｂ ０６０１（２００１）に規定される最大谷深さＲｖと、ＪＩＳ Ｂ ０６７１−２（２００２）に規定される突出山部断面積Ａ１（μｍ2）、突出谷部断面積Ａ２(μｍ2）を測定し、それぞれについて平均値を求めた。尚、リン酸マンガンで処理したもの（表１の試験Ｎｏ．２、３）については、ローラーピッチング試験後の試験片にて５％クロム酸溶液にてリン酸マンガン皮膜を除去した後、非摺動部にて粗さ測定を実施した。
[Measurement of surface properties]
In “CS3200” manufactured by Mitutoyo Co., Ltd., JIS B 0601 (4 mm, 90 mm on the circumference of the test piece shown in FIG. 2001), the maximum valley depth Rv specified in JIS B 0671-2 (2002), and the protruding peak section A1 (μm 2 ) and the protruding valley section A2 (μm 2 ) are measured. The average value was calculated | required about each. For the samples treated with manganese phosphate (Test Nos. 2 and 3 in Table 1), after removing the manganese phosphate film with a 5% chromic acid solution on the test piece after the roller pitching test, The roughness was measured at the moving part.
[凹部開口部分の開口径の測定]
レーザーテック社製「１ＬＭ２１Ｗ」にて、試験片表面に存在する凹部を１０００倍にて観察し、摺動方向の幅と摺動方向に対して垂直方向の幅の平均を、凹部の開口径と定義し、３視野の平均値を求めた。
[Measurement of opening diameter of recess opening]
With “1LM21W” manufactured by Lasertec, the concave portion present on the surface of the test piece was observed at 1000 times, and the average of the width in the sliding direction and the width perpendicular to the sliding direction was defined as the opening diameter of the concave portion. And the average value of 3 visual fields was calculated | required.
［歯面疲労損傷寿命の評価方法］
歯車特性の評価方法として、図２に示す二円筒試験片を用い、コマツ式二円筒試験機（ＲＰ２０１）にてローラーピッチング試験を実施した。ローラーピッチング試験は、前記試験片（小ローラ）と、同じ鋼種で作製された大ローラ（相手材）とを用いる。試験条件は、面圧：３ＧＰａ、回転速度：１５００ｒｐｍ、すべり速度１．２２ｍ／ｓであり、振動計にて歯面疲労損傷による振動停止までの繰返し数を測定し、これを歯面疲労損傷寿命とした。なお潤滑油としては市販されているＡＴＦを用いた。
[Evaluation method for tooth surface fatigue damage life]
As a method for evaluating gear characteristics, a roller pitching test was performed using a two-cylinder test piece (RP201) using a two-cylinder test piece shown in FIG. The roller pitching test uses the test piece (small roller) and a large roller (counter member) made of the same steel type. The test conditions were surface pressure: 3 GPa, rotation speed: 1500 rpm, sliding speed 1.22 m / s, and the number of repetitions until vibration stop due to tooth surface fatigue damage was measured with a vibrometer. It was. A commercially available ATF was used as the lubricating oil.
これらの結果（歯面疲労損傷寿命）を、試験片の表面性状（Ｒｖ、Ａ２、Ａ１、Ａ２／Ａ１、凹部開口径の平均値）と共に、下記表２に示す。 These results (tooth surface fatigue damage life) are shown in Table 2 below together with the surface properties of the test piece (Rv, A2, A1, A2 / A1, average value of recess opening diameter).
これらの結果から次のように考察することができる。まずＮｏ．４〜１０（試験Ｎｏ．の意味、以下同じ）は、適切な条件（酸洗条件）で試験片表面（歯車素地表面に相当）に凹部形状を形成することによって、表面性状は本発明で規定する要件を満足するものとなり、いずれも優れた歯面疲労損傷寿命が発揮されていることがわかる。このうちＮｏ．４のものは、本発明例中、酸洗溶液の温度が低く、酸洗処理時間が短く、好ましい要件である凹部開口径の平均値が若干小さくなっているものであり、Ｎｏ．５〜１０の発明例と比べて歯面疲労損傷寿命が若干低下しているが、基本的に問題のない程度である。 These results can be considered as follows. First, no. 4 to 10 (meaning of test No., the same applies hereinafter) is defined by the present invention by forming a concave shape on the surface of the test piece (corresponding to the gear substrate surface) under appropriate conditions (pickling conditions). It can be seen that all of them satisfy the requirements, and excellent tooth surface fatigue damage life is exhibited. Of these, No. No. 4 is a sample in which the temperature of the pickling solution is low, the pickling treatment time is short, and the average value of the recess opening diameter, which is a preferable requirement, is slightly smaller. Although the tooth surface fatigue damage life is slightly reduced as compared with the inventive examples of 5 to 10, it is basically a problem-free level.
これに対し、Ｎｏ．１〜３、１１〜２０では、試験片表面（歯車素地表面に相当）に形成される凹部形状が本発明で規定するいずれかの要件を外れるものとなっており、歯面疲労損傷寿命の向上が殆ど見られないことがわかる。即ち、Ｎｏ．１のものは、研磨仕上げしたままで潤滑処理を施していないものであり、表面に凹部が無いため歯面疲労損傷寿命が低くなっている。 In contrast, no. In 1-3, 11-20, the concave shape formed on the surface of the test piece (corresponding to the surface of the gear base) deviates from any of the requirements defined in the present invention, and the tooth surface fatigue damage life is improved. It can be seen that is hardly seen. That is, no. In the case of No. 1, the surface is polished and not lubricated, and since there are no recesses on the surface, the tooth surface fatigue damage life is low.
Ｎｏ．２、３のものは、リン酸マンガン処理を施したものであるが、硫酸で酸洗処理する場合と比べて、鉄に対する溶解力が弱くなり、前記比（Ａ２／Ａ１）の値が小さく、幅も小さくなるため、油溜り性が低くなり、歯面に加わる摩擦力が低減しないため歯面疲労損傷寿命が向上していない。 No. Although the thing of 2 and 3 is what gave the manganese phosphate process, compared with the case where it pickles with a sulfuric acid, the solubility with respect to iron becomes weak, and the value of the said ratio (A2 / A1) is small, Since the width is also reduced, the oil retention is reduced, and the frictional force applied to the tooth surface is not reduced, so the tooth surface fatigue damage life is not improved.
Ｎｏ．１１は、酸洗処理に用いた硫酸の温度が低い（室温）ものであり、酸溶液の腐食力が小さいために適正な凹部形状が生成しにくくなっており、前記比（Ａ２／Ａ１）が３よりも小さいものとなって油溜り性が改善されず、歯面に加わる摩擦力が低減しないため、歯面疲労損傷寿命が向上しない。 No. No. 11 is a low temperature (room temperature) sulfuric acid used for the pickling treatment, and since the corrosive force of the acid solution is small, it is difficult to form an appropriate concave shape, and the ratio (A2 / A1) is The oil retention is not improved and the frictional force applied to the tooth surface is not reduced, and the tooth surface fatigue damage life is not improved.
Ｎｏ．１２は、酸洗溶液の濃度が低いと腐食量が小さくなって、凹部が生成しないため油溜り性が低く歯面に加わる摩擦力が低減しないため、歯面疲労損傷寿命が向上していない。Ｎｏ．１３は、酸洗時の浸漬時間が短くなっており、前記比（Ａ２／Ａ１）の値が小さくなっているため、凹部による油溜り性が改善されず、歯面に加わる摩擦力が低減しないため、歯面疲労損傷寿命が向上していない。 No. No. 12, when the concentration of the pickling solution is low, the amount of corrosion becomes small, and no recess is formed, so that oil retention is low and the frictional force applied to the tooth surface is not reduced, so the tooth surface fatigue damage life is not improved. No. No. 13 has a shorter immersion time during pickling and a smaller value of the ratio (A2 / A1), so that the oil retention due to the recess is not improved and the frictional force applied to the tooth surface is not reduced. Therefore, the tooth surface fatigue damage life is not improved.
Ｎｏ．１４、１５は、酸洗時の硫酸濃度が高くなっており、最大谷深さ（Ｒｖ）が大きくなり、凹部が起点となって早期に破損が起こるため歯面疲労損傷寿命が短いくなっている。Ｎｏ．１６では、浸漬時間が長く、前記比（Ａ２／Ａ１）の値が大きく、また凹部の開口径の平均値が大きくなり、歯面の強度が低下するため歯面疲労損傷寿命が低下している。 No. Nos. 14 and 15 have a high sulfuric acid concentration at the time of pickling, the maximum valley depth (Rv) becomes large, and the tooth surface fatigue damage life becomes short because breakage occurs at an early stage starting from the recess. Yes. No. In No. 16, the immersion time is long, the value of the ratio (A2 / A1) is large, the average value of the opening diameters of the recesses is large, and the tooth surface strength is reduced, so that the tooth surface fatigue damage life is reduced. .
Ｎｏ．１７では、酸洗時の浸漬時間が長くなって、前記比（Ａ２／Ａ１）の値が大きくなり、最大谷深さＲｖおよび凹部の開口径の平均値が大きくなり、凹部が起点となって歯面の強度が低下するため歯面疲労損傷寿命が低下している。 No. In No. 17, the immersion time during pickling is increased, the value of the ratio (A2 / A1) is increased, the average value of the maximum valley depth Rv and the opening diameter of the recess is increased, and the recess is the starting point. Since the strength of the tooth surface is reduced, the tooth surface fatigue damage life is reduced.
Ｎｏ．１８〜２０は、塩酸による酸洗処理（濃度１０〜３０％、常温）を行ったものであるが、硫酸で酸洗処理する場合と比べて鉄に対する溶解力が弱く、前記比（Ａ２／Ａ１）の値が小さいため歯面に加わる摩擦力が低減せず、歯面疲労損傷寿命が向上していない。 No. Nos. 18 to 20 are those subjected to pickling treatment with hydrochloric acid (concentration 10 to 30%, normal temperature), but have a lower solubility in iron than the case of pickling treatment with sulfuric acid, and the ratio (A2 / A1) ) Is small, the frictional force applied to the tooth surface is not reduced, and the tooth surface fatigue damage life is not improved.
Claims (2)
The gear excellent in tooth surface fatigue damage life according to claim 1, wherein an average value of opening diameters in recesses existing on the surface of the gear base is 16 to 30 μm.
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