JP3271659B2 - High strength gear and manufacturing method thereof - Google Patents
High strength gear and manufacturing method thereofInfo
- Publication number
- JP3271659B2 JP3271659B2 JP18281198A JP18281198A JP3271659B2 JP 3271659 B2 JP3271659 B2 JP 3271659B2 JP 18281198 A JP18281198 A JP 18281198A JP 18281198 A JP18281198 A JP 18281198A JP 3271659 B2 JP3271659 B2 JP 3271659B2
- Authority
- JP
- Japan
- Prior art keywords
- gear
- tooth
- core
- tooth surface
- strength
- 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.)
- Expired - Fee Related
Links
Landscapes
- Gears, Cams (AREA)
- Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)
- Heat Treatment Of Articles (AREA)
Description
【0001】[0001]
【発明の属する技術分野】本発明は、高面圧で使用され
る動力伝達用歯車などとして好適な高強度歯車およびそ
の製造方法に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-strength gear suitable as a power transmission gear used at a high surface pressure and a method for manufacturing the same.
【0002】[0002]
【従来の技術】近年、自動車等の燃費低減あるいは排ガ
ス低減を目的とする軽量化、さらには、高出力化の要求
が高まってきている。そして、ユニットサイズを上げる
ことなく高い駆動力を伝達するために、動力伝達用歯車
の歯面に負荷される面圧は非常に厳しくなっており、接
触面の剥離現象であるピッチングや接触面の摩耗が問題
となることもありえないことではない。2. Description of the Related Art In recent years, there has been an increasing demand for weight reduction for the purpose of reducing fuel consumption or exhaust gas of automobiles and the like, and also for higher output. In order to transmit high driving force without increasing the unit size, the surface pressure applied to the tooth surface of the power transmission gear is extremely severe, and pitching or contact surface, which is a phenomenon of contact surface separation, is occurring. It is not impossible that wear is a problem.
【0003】この問題に対応しようとする従来技術とし
ては、例えば、歯車の表面に高濃度の浸炭を行い、微細
な炭化物を析出させて、高い硬度を得る方法があり、歯
車への適用についても多くの出願(例えば、特開平7−
3430号公報など)がなされている。As a conventional technique for solving this problem, for example, there is a method of performing high concentration carburization on the surface of a gear to precipitate fine carbides to obtain a high hardness. Many applications (for example,
No. 3430).
【0004】しかし、歯車においては、歯面の強度と同
時に歯元の靭性が求められ、曲げ応力による疲労や衝撃
強度を確保せねばならないため、歯面の硬度と歯元の靭
性を両立させるには歯元の靭性を損なうほどの高濃度の
浸炭をおこなうことはできなかった。そのため、炭化物
を析出させることで歯面強度の向上をはかるには、例え
ば、特開平6−17189号公報に記載のように、炭化
物の面積率を低く規定したり、加熱−冷却サイクルによ
る球状化処理により炭化物の形状を制御する処理(例え
ば、特開平2−156063号公報)を加える必要があ
った。However, in the gear, the toughness of the tooth root is required at the same time as the strength of the tooth surface, and the fatigue and impact strength due to bending stress must be ensured. Could not perform carburization at a high concentration enough to impair the toughness of the tooth root. Therefore, in order to improve the tooth surface strength by precipitating carbide, for example, as described in JP-A-6-17189, the area ratio of carbide is specified to be low, or spheroidization by a heating-cooling cycle is performed. It was necessary to add a process for controlling the shape of the carbide by the process (for example, JP-A-2-15663).
【0005】一方、歯元の疲労強度を向上させるための
方法としては、硬質粒子を歯車に投射するショットピー
ニングが広く用いられている。その主要な効果は歯車の
表面の圧縮残留応力が付与されるためと考えられてお
り、大きな圧縮残留応力を与えるために、投射速度を高
める、いわゆるハードショットピーニングが開発されて
いる。[0005] On the other hand, as a method for improving the fatigue strength of the tooth root, shot peening in which hard particles are projected onto a gear is widely used. It is considered that the main effect is that compressive residual stress on the surface of the gear is applied, and so-called hard shot peening, in which the projection speed is increased to give a large compressive residual stress, has been developed.
【0006】しかし、ハードショットピーニングを行う
と、歯先が塑性変形して潰れてしまい、修正加工を行う
必要がある。また、歯車の表面に炭化物を析出させるよ
うな場合に、修正加工を行うと歯車表層の炭化物が失わ
れしまい、さらにまた、硬度が高いために工具の摩耗も
大きくなってしまう。However, when hard shot peening is performed, the tip of the tooth is plastically deformed and crushed, and it is necessary to perform a correction process. Further, in the case where carbide is precipitated on the surface of the gear, if the correction processing is performed, the carbide on the surface layer of the gear is lost, and since the hardness is high, the wear of the tool is increased.
【0007】このほか、歯面と歯元に要求される異なる
強度特性を両立させるためには、歯面と歯元の浸炭深さ
を変える方法が考えられているが、従来の技術では歯面
と歯元での浸炭深さや炭化物量を変え、硬度差を与える
ことにとどまっており、炭化物の有無がその後の処理、
例えば、窒化やショットピーニングに及ぼす影響に注目
しているものはない。In addition, a method of changing the carburizing depth between the tooth surface and the tooth root has been considered in order to achieve the different strength characteristics required for the tooth surface and the tooth root. And changing the carburization depth and carbide amount at the root of the tooth to give a difference in hardness.
For example, none has focused on the effects on nitriding or shot peening.
【0008】[0008]
【発明の目的】本発明は、このような従来の問題点に着
目してなされたもので、本発明者の研究によれば、炭化
物量およびオーステナイト状態での炭素濃度の差は、そ
の後の窒化処理や焼き戻し硬度、さらにはショットピー
ニングを行った際の反応に大きく影響を与えることが確
かめられたことから、本発明はこの現象を利用すること
により、歯車の歯面と歯元の組織を最適に制御し、歯面
と歯元のそれぞれに要求される強度特性を両立させた高
強度歯車およびその製造方法を提供することを目的とし
ている。SUMMARY OF THE INVENTION The present invention has been made in view of such a conventional problem. According to the study of the present inventors, the difference between the amount of carbide and the carbon concentration in the austenite state is reduced by the subsequent nitriding. It has been confirmed that this has a significant effect on the treatment and tempering hardness, and furthermore on the reaction when shot peening is performed.The present invention utilizes this phenomenon to reduce the tooth surface and tooth root structure of the gear. It is an object of the present invention to provide a high-strength gear that is optimally controlled, and achieves both the strength characteristics required for the tooth surface and the tooth root, and a method for manufacturing the same.
【0009】[0009]
【課題を解決するための手段】本発明に係わる高強度歯
車は、請求項1に記載しているように、歯車の駆動側お
よび被駆動側の歯面のかみ合い範囲においては歯面の最
表層から芯部方向に少なくとも0.2mmの深さまで面
積率で5〜10%の炭化物が分散析出し、かつ、当該歯
車の駆動側および被駆動側の歯元すみR部においては最
表層から芯部にかけての炭化物が面積率で最大3%であ
り、かつ、球状ないし擬球状に分散析出していると共
に、窒化処理が施されていて、前記かみ合い範囲におい
ては歯面の最表層から芯部にかけての窒素濃度分布のピ
ークが0.3wt%以下であり、前記歯元すみR部にお
いては最表層から芯部にかけての窒素濃度分布のピーク
が0.3wt%以上であるものとしたことを特徴として
いる。According to the present invention, a high-strength gear according to the present invention has an outermost surface of a tooth surface in a meshing range of a tooth surface on a driving side and a driven side of the gear. From 5% to 10% in area ratio from the outermost layer to the core portion in the direction of the core portion, and from the outermost layer to the core portion at the root portion R at the driving side and the driven side of the gear. The carbonized material having a maximum area ratio of 3% is dispersed and precipitated in a spherical or pseudo spherical shape, and is subjected to a nitriding treatment. In the meshing range, the carbide from the outermost layer of the tooth surface to the core is formed. The peak of the nitrogen concentration distribution is 0.3 wt% or less, and the peak of the nitrogen concentration distribution from the outermost surface layer to the core is 0.3 wt% or more in the root corner R portion. .
【0010】そして、本発明に係わる高強度歯車の実施
態様においては、請求項2に記載しているように、歯車
の歯面のかみ合い範囲においては歯面の最表層から芯部
にかけての残留オーステナイト量分布のピークが30w
t%以下であり、かつ、当該歯車の歯元すみR部におい
ては最表層から芯部にかけての残留オーステナイト量分
布のピークが25〜45wt%であるものとすることが
できる。In the embodiment of the high-strength gear according to the present invention, as described in claim 2, the retained austenite from the outermost surface layer of the tooth surface to the core portion in the meshing range of the tooth surface of the gear. 30w peak of quantity distribution
and the peak of the distribution of the retained austenite amount from the outermost layer to the core at the corner R of the tooth root of the gear is 25 to 45 wt%.
【0011】同じく、本発明に係わる高強度歯車の実施
態様においては、請求項3に記載しているように、歯車
の歯面のかみ合い範囲においては歯面の最表層の硬度が
Hv800以上であり、かつ、当該歯車の歯元すみR部
においては最表層の硬度がHv700〜800であるも
のとすることができる。Similarly, in the embodiment of the high-strength gear according to the present invention, the hardness of the outermost layer of the tooth surface is Hv800 or more in the meshing range of the tooth surface as described in claim 3. In addition, the hardness of the outermost layer in the tooth corner radius R portion of the gear can be Hv700 to 800.
【0012】本発明に係わる高強度歯車の製造方法は、
請求項4に記載しているように、歯車素材の浸炭処理後
に冷却ないしは冷却および加熱処理を施して炭化物を析
出させたあと窒化処理を施すことにより、歯車の駆動側
および被駆動側の歯面のかみ合い範囲においては歯面の
最表層から芯部方向に少なくとも0.2mmの深さまで
面積率で5〜10%の炭化物を分散析出させ、かつ、当
該歯車の駆動側および被駆動側の歯元すみR部において
は最表層から芯部にかけての炭化物を面積率で最大3%
とし、かつ、球状ないし擬球状に分散析出させると共
に、前記かみ合い範囲においては歯面の最表層から芯部
にかけての窒素濃度分布のピークを0.3wt%以下と
し、前記歯元すみR部においては最表層から芯部にかけ
ての窒素濃度分布のピークを0.3wt%以上とするよ
うにしたことを特徴としている。[0012] The method for manufacturing a high-strength gear according to the present invention comprises:
As described in claim 4, after the carburizing process of the gear material, cooling or cooling and heating processes are performed to precipitate carbides, and then the nitriding process is performed. In the meshing range, 5 to 10% of carbide is dispersed and precipitated at an area ratio from the outermost surface of the tooth surface to a depth of at least 0.2 mm in the direction of the core, and the roots on the driving side and the driven side of the gear. In the corner R part, the carbide from the outermost layer to the core is up to 3% in area ratio.
In addition, in the meshing range, the peak of the nitrogen concentration distribution from the outermost surface layer of the tooth surface to the core is set to 0.3 wt% or less in the meshing range. It is characterized in that the peak of the nitrogen concentration distribution from the outermost layer to the core is set to 0.3 wt% or more.
【0013】そして、本発明に係わる高強度歯車の製造
方法の実施態様においては、請求項5に記載しているよ
うに、歯車の歯面のかみ合い範囲においては歯面の最表
層から芯部にかけての残留オーステナイト量分布のピー
クを30wt%以下とし、かつ、当該歯車の歯元すみR
部においては最表層から芯部にかけての残留オーステナ
イト量分布のピークを25〜45wt%とするようにな
すことができる。According to an embodiment of the method for manufacturing a high-strength gear according to the present invention, as described in claim 5, in the meshing range of the tooth surface of the gear, from the outermost surface layer of the tooth surface to the core. The peak of the residual austenite distribution of the gear is 30 wt% or less, and the tooth corner R
In the part, the peak of the amount distribution of retained austenite from the outermost layer to the core can be 25 to 45 wt%.
【0014】同じく、本発明に係わる高強度歯車の製造
方法の実施態様においては、請求項6に記載しているよ
うに、浸炭ないしは浸炭および窒化処理後の焼き戻し処
理により、歯車の歯面のかみ合い範囲においては歯面の
最表層の硬度をHv800以上とし、かつ、当該歯車の
歯元すみR部においては最表層の硬度をHv700〜8
00とするようになすことができる。Similarly, in an embodiment of the method for manufacturing a high-strength gear according to the present invention, as described in claim 6, the tooth surface of the gear is formed by carburizing or tempering after carburizing and nitriding. In the meshing range, the hardness of the outermost layer of the tooth surface is Hv800 or more, and the hardness of the outermost layer is Hv700 to 8 in the tooth root radius R portion of the gear.
00.
【0015】同じく、本発明に係わる高強度歯車の製造
方法の実施態様においては、請求項7に記載しているよ
うに、歯元すみR部に場合によっては希釈した浸炭制御
剤を塗布した後、浸炭処理を行うようになすことができ
る。Similarly, in an embodiment of the method for manufacturing a high-strength gear according to the present invention, as described in claim 7, after the carburizing control agent diluted in some cases is applied to the root corner R, the carburizing control agent may be applied. , Carburizing treatment can be performed.
【0016】同じく、本発明に係わる高強度歯車の製造
方法の実施態様においては、請求項8に記載しているよ
うに、浸炭処理後に浸炭制御剤を除去し、続いて窒化処
理および2次焼き入れを行うようになすことができる。Similarly, in an embodiment of the method for manufacturing a high-strength gear according to the present invention, the carburizing control agent is removed after the carburizing treatment, followed by the nitriding treatment and the secondary firing. Can be put in place.
【0017】同じく、本発明に係わる高強度歯車の製造
方法の実施態様においては、請求項9に記載しているよ
うに、200〜250℃にて焼き戻しを行うようになす
ことができる。Similarly, in an embodiment of the method for manufacturing a high-strength gear according to the present invention, as described in claim 9, tempering can be performed at 200 to 250 ° C.
【0018】同じく、本発明に係わる高強度歯車の製造
方法の実施態様においては、請求項10に記載している
ように、粒径0.4mm以下の硬質粒子をアークハイト
0.3〜0.8mmとなるように投射するショットピー
ニングを行うようになすことができる。Similarly, in an embodiment of the method for manufacturing a high-strength gear according to the present invention, as described in claim 10, hard particles having a particle size of 0.4 mm or less are formed with an arc height of 0.3 to 0. Shot peening for projection so as to be 8 mm can be performed.
【0019】同じく、本発明に係わる高強度歯車の製造
方法の実施態様においては、請求項11に記載している
ように、浸炭処理をプラズマ浸炭法により行うようにな
すことができる。Similarly, in an embodiment of the method for manufacturing a high-strength gear according to the present invention, the carburizing treatment may be performed by a plasma carburizing method.
【0020】[0020]
【発明の作用】本発明による高強度歯車およびその製造
方法では、使用する材料を特に限定するものではなく、
JIS G 4051で制定するSC材、JIS G
4102で制定するSNC材、JIS G 4103で
制定するSNCM材、JISG 4104で制定するS
Cr材、JIS G 4105で制定するSCM材、J
IS G 4106で制定するSMn材やSMnC材お
よびこれらの改良材などを用いることができるが、炭化
物の析出により母層から失われる焼入れ性向上元素、例
えば、Crの欠乏を補うことができるような焼入れ性向
上元素を含有している材料を用いることがより望まし
い。In the high-strength gear and the method of manufacturing the same according to the present invention, the materials used are not particularly limited.
SC material established by JIS G 4051, JIS G
SNC material specified in 4102, SNCM material specified in JIS G 4103, S specified in JISG 4104
Cr material, SCM material established by JIS G 4105, J
The SMn material and the SMnC material defined by IS G 4106 and their improved materials can be used. However, the hardening property improving element lost from the base layer due to the precipitation of carbide, for example, Cr, can be compensated. It is more desirable to use a material containing a hardenability improving element.
【0021】そこで、本発明の説明にあたっては、素材
として、JIS G 4105で制定するSCM420
Hを用いることとし、この素材を用いて各種試験片の形
状に加工した。Therefore, in the description of the present invention, as a material, SCM420 specified in JIS G 4105 is used.
H was used, and this material was used to process various test pieces.
【0022】次いで、各試験片に対し図1に示すパター
ンにて浸炭焼入れ焼き戻しを行った。そして、浸炭では
雰囲気のカーボンポテンシャル(Cp)を0.8〜1.
4の範囲で変えることにより球状ないしは擬球状に分散
析出している炭化物の面積率を変動させた。そして、そ
の後の炭化物の面積率の測定に際しては、粒界酸化層を
避け、最表面から0.2mmの範囲において走査型電子
顕微鏡で10000倍の写真をとり、画像解析にて求め
た。Next, each test piece was carburized, quenched and tempered according to the pattern shown in FIG. In carburizing, the carbon potential (Cp) of the atmosphere is set to 0.8 to 1.
By changing the ratio in the range of 4, the area ratio of carbides dispersed and precipitated in a spherical or pseudospherical shape was varied. In the subsequent measurement of the area ratio of carbide, a 10,000 × photograph was taken with a scanning electron microscope in a range of 0.2 mm from the outermost surface, avoiding the grain boundary oxide layer, and was obtained by image analysis.
【0023】また、ピッチングおよび摩耗強度の測定に
際しては、破損確率50%寿命をとり、回転数:150
0rpm、滑り率:40%、面圧:5000MPaの条
件でのローラーピッチング試験を行った。In measuring the pitting and the wear strength, a life of 50% of failure was taken, and the number of rotations was 150.
A roller pitching test was performed under the conditions of 0 rpm, a slip ratio: 40%, and a surface pressure: 5000 MPa.
【0024】さらに、疲労強度の測定に際しては、形状
係数2.0の試験片で回転曲げを行い、107サイクル
寿命を調べた。また、静的曲げ強度および繰り返し衝撃
寿命(1500MPa)の測定に際しては10mm角の
曲げ試験片を用いて調べた。このようにして得られた結
果を表1に示す。Further, when measuring the fatigue strength, a test piece having a shape factor of 2.0 was subjected to rotational bending, and a 107 cycle life was examined. Further, when measuring the static bending strength and the repeated impact life (1500 MPa), a 10 mm square bending test piece was used. Table 1 shows the results thus obtained.
【0025】[0025]
【表1】 [Table 1]
【0026】表1に示すように、まず、ローラーピッチ
ング試験の結果をみると、寿命および摩耗量は炭化物の
面積率を上げるほど向上する傾向にある。これは炭化物
が高温でも安定なため、炭化物が少ないものに比べて硬
度の低下を抑制する働きをしているためと理解できる。
例えば、図2は300℃で焼き戻しを行ったときの表面
硬度とローラーピッチング寿命の関係を示したものであ
るが、ピッチング強度は高温硬度とよい対応関係がある
ことがわかる。As shown in Table 1, first, the results of the roller pitting test show that the life and the amount of wear tend to increase as the area ratio of carbide increases. This can be understood from the fact that the carbide is stable even at a high temperature, and thus has a function of suppressing a decrease in hardness as compared with a carbide having a small amount of carbide.
For example, FIG. 2 shows the relationship between the surface hardness and the roller pitting life when tempering at 300 ° C. It can be seen that the pitting strength has a good correspondence with the high temperature hardness.
【0027】しかし、表1に示す結果からわかるよう
に、炭化物の面積率が10%を超えると炭化物が塊状に
合体し、安定して微細分散させることが困難となるた
め、寿命は逆に低下してしまう。このため、歯面におけ
る炭化物の面積率としては本発明の範囲である5〜10
%が適切と考えられる。また、その深さは通常の使用条
件の場合、最大せん断応力深さを考慮しても0.2mm
まであればよい。However, as can be seen from the results shown in Table 1, when the area ratio of the carbide exceeds 10%, the carbides are coalesced into a lump and it is difficult to stably and finely disperse. Resulting in. Therefore, the area ratio of carbide on the tooth surface is within the range of 5 to 10 which is within the range of the present invention.
% Is considered appropriate. In addition, the depth is 0.2 mm in the case of a normal use condition, even in consideration of the maximum shear stress depth.
You only have to do it.
【0028】一方、曲げ疲労強度も炭化物の面積率をあ
る程度まで上げるほど増加するが、静的曲げ破断強度お
よび繰り返し衝撃寿命は歯車の歯元での炭化物の面積率
が3%を超えると急激に低下してしまう。このことか
ら、歯車の歯元での炭化物の面積率は3%以下が適切と
考えられる。On the other hand, the bending fatigue strength also increases as the area ratio of carbide is increased to a certain extent, but the static bending rupture strength and the repeated impact life sharply increase when the area ratio of carbide at the root of the gear exceeds 3%. Will drop. From this, it is considered appropriate that the area ratio of carbide at the root of the gear is 3% or less.
【0029】以上説明したように、本発明によれば、歯
面の耐ピッチング性および耐摩耗性ならびに歯元の曲げ
疲労強度および耐衝撃性を最適にした高強度歯車とする
ことができる。As described above, according to the present invention, it is possible to obtain a high-strength gear in which the pitting resistance and the wear resistance of the tooth surface and the bending fatigue strength and the impact resistance of the tooth root are optimized.
【0030】なお、本発明では高濃度の浸炭が要求され
ることから、浸炭工程をプラズマ浸炭で行うのがよい。
これは真空での処理が行えることから高温下であっても
粒界酸化が生じず、また、浸炭を迅速におこなうことが
できるためである。In the present invention, since high-concentration carburization is required, the carburization step is preferably performed by plasma carburization.
This is because the treatment can be performed in a vacuum, so that grain boundary oxidation does not occur even at a high temperature, and carburizing can be performed quickly.
【0031】次に、前記各試験片に対し、図3に示すパ
ターンにて浸炭処理した後、NH3ガス中での窒化処理
を行った。このときのカーボンポテンシャル(Cp)は
図1のパターンと同じ条件で変動させた。そして、最表
面から芯部方向への炭素および窒素濃度分布をEPMA
にて調べた結果を表2に示す。Next, the test pieces were carburized in the pattern shown in FIG. 3 and then nitrided in NH 3 gas. The carbon potential (Cp) at this time was varied under the same conditions as in the pattern of FIG. Then, the distribution of carbon and nitrogen concentrations from the outermost surface toward the core is determined by EPMA.
Table 2 shows the results of the examination.
【0032】[0032]
【表2】 [Table 2]
【0033】表2に示した結果より明らかなように、炭
化物の面積率が多いものほど窒素濃度は低くなることが
わかる。このことから、前記したように、歯面と歯元の
炭化物面積率をそれぞれ5〜10%および3%以下とし
ておけば、その後同じ条件で窒化しても、歯面と歯元で
は浸入する窒素量に違いが生じる。また、残留オーステ
ナイト量は窒素濃度が高いほど多くなる傾向にあり、窒
素量が歯面よりも多い歯元では、より優れた靭性が得ら
れることになる。逆に、高い硬度が要求される歯面では
残留オーステナイト量が少なく、高い硬度を得易いこと
になる。As is clear from the results shown in Table 2, it is understood that the nitrogen concentration becomes lower as the area ratio of the carbide is larger. From this, as described above, if the carbide area ratio of the tooth surface and the tooth root is set to 5% to 10% and 3% or less, respectively, even if nitriding is carried out under the same conditions, nitrogen entering the tooth surface and the tooth root will enter. Differences in volume occur. Further, the amount of retained austenite tends to increase as the nitrogen concentration increases, and more excellent toughness can be obtained in a tooth root where the nitrogen amount is larger than the tooth surface. Conversely, on the tooth surface where high hardness is required, the amount of retained austenite is small and high hardness is easily obtained.
【0034】表2に示した結果から、歯面強度を従来に
対して有効に向上させるためには、硬度をHv800以
上とすることが必要と考えられるが、窒素を0.3wt
%以上与えた場合は残留オーステナイトが多量に生成す
る結果となっており、安定した高い硬度を得ることは困
難である傾向となる。一方、歯元では窒素濃度分布のピ
ークを0.3wt%以上、残留オーステナイト量分布の
ピークを25〜45wt%、最表層の硬度をHv700
〜800の範囲とすることで、従来の歯車と同等以上の
曲げ疲労強度および衝撃強度を得ることができる。From the results shown in Table 2, it is considered that the hardness must be Hv 800 or more in order to effectively improve the tooth surface strength as compared with the conventional one.
%, A large amount of retained austenite is produced, and it tends to be difficult to obtain a stable and high hardness. On the other hand, at the root, the peak of the nitrogen concentration distribution is 0.3 wt% or more, the peak of the residual austenite distribution is 25 to 45 wt%, and the hardness of the outermost layer is Hv700.
By setting the range to 800, it is possible to obtain a bending fatigue strength and an impact strength equal to or higher than those of a conventional gear.
【0035】次に、前記各試験片に対し、図4に示すパ
ターンにより、浸炭および窒化処理した後の焼き戻し温
度が硬度低下に及ぼす影響を調べた。この結果を表3に
示す。Next, the effect of the tempering temperature after carburizing and nitriding treatment on the hardness reduction of each of the above test pieces was examined using the pattern shown in FIG. Table 3 shows the results.
【0036】[0036]
【表3】 [Table 3]
【0037】既に述べたように、炭化物は焼き戻し温度
程度では安定なため、炭化物が多い場合には硬度の低下
は少なく、炭化物が少ない場合には大きく軟化する。そ
のため、歯面部分の炭化物が5〜10面積%でかつ歯元
部分の炭化物が3面積%以下である組織とした後、高温
で焼き戻しを行えば、歯面硬度を維持し、かつまた、歯
元硬度は低下するため、より優れた靭性を付与すること
ができる。As described above, the carbide is stable at about the tempering temperature. Therefore, when the amount of the carbide is large, the decrease in hardness is small, and when the amount of the carbide is small, the carbide is greatly softened. For this reason, if the structure in which the carbide in the tooth surface portion is 5 to 10 area% and the carbide in the root portion is 3 area% or less, and then tempering at a high temperature, the tooth surface hardness is maintained, and Since the root hardness decreases, more excellent toughness can be provided.
【0038】表3に示すように、焼き戻しは200℃以
上にて上記の効果が十分に発揮される。しかし、250
℃を超えると焼き戻し脆化域となってしまううえ、これ
以上の高温では歯面硬度を維持することも困難になるた
め、200〜250℃の範囲とするのがより適切な条件
である。As shown in Table 3, the above effects are sufficiently exhibited in tempering at 200 ° C. or higher. But 250
If the temperature exceeds ℃, it becomes a tempering embrittlement zone, and if the temperature is higher than this, it becomes difficult to maintain the tooth surface hardness. Therefore, the temperature is more preferably set to the range of 200 to 250 ° C.
【0039】さらに、本発明による高強度歯車の製造方
法では、粒径0.4mm以下の硬質粒子をアークハイト
0.3〜0.8mmとなるように投射するショットピー
ニングを行うことも必要に応じて望ましく、このような
ショットピーニングを行うことによって歯車に圧縮残留
応力を付与することが可能であり、歯車の疲労強度がさ
らに向上したものとなる。Further, in the method for manufacturing a high-strength gear according to the present invention, shot peening for projecting hard particles having a particle size of 0.4 mm or less so as to have an arc height of 0.3 to 0.8 mm may be performed as necessary. Desirably, by performing such shot peening, it is possible to impart a compressive residual stress to the gear, and the fatigue strength of the gear is further improved.
【0040】[0040]
【発明の効果】本発明による高強度歯車では、請求項1
に記載しているように、歯車の駆動側および被駆動側の
歯面のかみ合い範囲においては歯面の最表層から芯部方
向に少なくとも0.2mmの深さまで面積率で5〜10
%の炭化物が分散析出し、かつ、当該歯車の駆動側およ
び被駆動側の歯元すみR部においては最表層から芯部に
かけての炭化物が面積率で最大3%であり、かつ、球状
ないし擬球状に分散析出していると共に、窒化処理が施
されていて、歯面のかみ合い範囲においては歯面の最表
層から芯部にかけての窒素濃度分布のピークが0.3w
t%以下であり、歯車の歯元すみR部においては最表層
から芯部にかけての窒素濃度分布のピークが0.3wt
%以上であるものとしたから、歯元部分での窒素量が歯
面部分よりも多いものとなって歯元部分での靭性をより
優れたものにすることができ、歯面の耐ピッチング性お
よび耐摩耗性ならびに歯元の曲げ疲労強度および耐衝撃
性を最適にした高強度歯車を提供することが可能である
という著しく優れた効果がもたらされる。According to the present invention, there is provided a high-strength gear according to the present invention.
As described in the above, in the meshing range of the tooth surface on the driving side and the driven side of the gear, the area ratio is 5 to 10 from the outermost surface of the tooth surface to the depth of at least 0.2 mm in the core direction.
% Of carbide is dispersed and precipitated, and at the tooth corner R at the driving side and the driven side of the gear, the carbide from the outermost layer to the core has a maximum area ratio of 3%, and is spherical or pseudo. It is spherically dispersed and precipitated, and is subjected to nitriding treatment. In the meshing range of the tooth surface, the peak of the nitrogen concentration distribution from the outermost surface layer of the tooth surface to the core is 0.3 watts.
t% or less, and the peak of the nitrogen concentration distribution from the outermost layer to the core at the root portion of the tooth root is 0.3 wt%.
%, The amount of nitrogen in the tooth root portion is larger than that in the tooth surface portion, and the toughness in the tooth root portion can be improved, and the pitting resistance of the tooth surface can be improved. In addition, it is possible to provide a high-strength gear in which the wear resistance and the bending fatigue strength of the tooth root and the impact resistance are optimized.
【0041】そして、請求項2に記載しているように、
歯車の歯面のかみ合い範囲においては歯面の最表層から
芯部にかけての残留オーステナイト量分布のピークが3
0wt%以下であり、かつ、当該歯車の歯元すみR部に
おいては最表層から芯部にかけての残留オーステナイト
量分布のピークが25〜45wt%であるものとするこ
とによって、高い硬度が要求される歯面では残留オース
テナイト量が少なく、高い硬度を得やすいものとなって
歯面部分での耐摩耗性をより優れたものとすることがで
き、歯面の耐ピッチング性および耐摩耗性ならびに歯元
の曲げ疲労強度および耐衝撃性をさらに良好なものとし
た高強度歯車を提供することが可能であるという著しく
優れた効果がもたらされる。And, as described in claim 2,
In the meshing range of the gear tooth surface, the peak of the residual austenite distribution from the outermost layer of the tooth surface to the core has a peak of 3%.
High hardness is required by setting the peak of the residual austenite amount distribution from the outermost layer to the core at 25% to 45% by weight in the tooth root radius R portion of the gear. The tooth surface has a small amount of retained austenite, and it is easy to obtain high hardness, which makes it possible to further improve the wear resistance at the tooth surface, and the pitting and wear resistance of the tooth surface and the tooth root A remarkably excellent effect is that it is possible to provide a high-strength gear with further improved bending fatigue strength and impact resistance.
【0042】さらにまた、請求項3に記載しているよう
に、歯車の歯面のかみ合い範囲においては歯面の最表層
の硬度がHv800以上であり、かつ、当該歯車の歯元
すみR部においては最表層の硬度がHv700〜800
であるものとすることによって、歯面強度をさらに向上
したものとすることが可能であり、歯面の耐ピッチング
性および耐摩耗性ならびに歯元の曲げ疲労強度および耐
衝撃性をさらに良好なものとした高強度歯車を提供する
ことが可能であるという著しく優れた効果がもたらされ
る。Further, as described in the third aspect, in the meshing range of the tooth surface of the gear, the hardness of the outermost layer of the tooth surface is Hv800 or more, and at the tooth corner radius R portion of the gear. Means that the hardness of the outermost layer is Hv 700 to 800
, It is possible to further improve the tooth surface strength, and to further improve the pitting resistance and wear resistance of the tooth surface and the bending fatigue strength and impact resistance of the tooth root A remarkably excellent effect that it is possible to provide a high-strength gear having a reduced strength.
【0043】本発明による高強度歯車の製造方法では、
請求項4に記載しているように、歯車素材の浸炭処理後
に冷却ないしは冷却および加熱処理を施して炭化物を析
出させたあと窒化処理を施すことにより、歯車の駆動側
および被駆動側の歯面のかみ合い範囲においては歯面の
最表層から芯部方向に少なくとも0.2mmの深さまで
面積率で5〜10%の炭化物を分散析出させ、かつ、当
該歯車の駆動側および被駆動側の歯元すみR部において
は最表層から芯部にかけての炭化物を面積率で最大3%
とし、かつ、球状ないし擬球状に分散析出させると共
に、歯面のかみ合い範囲においては歯面の最表層から芯
部にかけての窒素濃度分布のピークを0.3wt%以下
とし、当該歯車の歯元すみR部においては最表層から芯
部にかけての窒素濃度分布のピークを0.3wt%以上
とするようにしているから、歯元部分での窒素量を歯面
部分よりも多いものとすることが可能であり、歯元部分
での靭性をより優れたものにすることが可能であって、
歯面の耐ピッチング性および耐摩耗性ならびに歯元の曲
げ疲労強度および耐衝撃性を最適にした高強度歯車を製
造することが可能であるという著しく優れた効果がもた
らされる。In the method for manufacturing a high-strength gear according to the present invention,
As described in claim 4, after the carburizing process of the gear material, cooling or cooling and heating processes are performed to precipitate carbides, and then the nitriding process is performed. In the meshing range, 5 to 10% of carbide is dispersed and precipitated at an area ratio from the outermost surface of the tooth surface to a depth of at least 0.2 mm in the direction of the core, and the roots on the driving side and the driven side of the gear. In the corner R part, the carbide from the outermost layer to the core is up to 3% in area ratio
And in a spherical or pseudo-spherical state, the peak of the nitrogen concentration distribution from the outermost surface layer of the tooth surface to the core is set to 0.3 wt% or less in the meshing range of the tooth surface, and In the R portion, the peak of the nitrogen concentration distribution from the outermost layer to the core is set to 0.3 wt% or more, so that the nitrogen amount at the root portion can be larger than that at the tooth surface portion. It is possible to make the toughness at the root part more excellent,
A remarkably excellent effect is obtained that it is possible to manufacture a high-strength gear in which the pitting resistance and the wear resistance of the tooth surface and the bending fatigue strength and the impact resistance of the root are optimized.
【0044】そして、請求項5に記載しているように、
歯車の歯面のかみ合い範囲においては歯面の最表層から
芯部にかけての残留オーステナイト量分布のピークを3
0wt%以下とし、かつ、当該歯車の歯元すみR部にお
いては最表層から芯部にかけての残留オーステナイト量
分布のピークを25〜45wt%とするようなすことに
よって、高い硬度が要求される歯面では残留オーステナ
イト量が少ないものとすることができ、高い硬度を得る
ことが可能となって歯面部分での耐摩耗性をより優れた
ものとすることが可能であり、歯面の耐ピッチング性お
よび耐摩耗性ならびに歯元の曲げ疲労強度および耐衝撃
性がさらに良好な高強度歯車を製造することが可能であ
るという著しく優れた効果がもたらされる。And, as described in claim 5,
In the meshing range of the gear tooth surface, the peak of the residual austenite distribution from the outermost layer of the tooth surface to the core is 3
0 wt% or less and the peak of the distribution of retained austenite from the outermost surface layer to the core at the corner R of the root of the gear is set to 25 to 45 wt%, so that a tooth surface requiring high hardness is required. In this case, the amount of retained austenite can be reduced, high hardness can be obtained, and the wear resistance at the tooth surface can be further improved, and the pitting resistance of the tooth surface can be improved. In addition, a remarkably excellent effect is obtained in that it is possible to manufacture a high-strength gear having even better wear resistance, root bending fatigue strength and impact resistance.
【0045】さらにまた、請求項6に記載しているよう
に、浸炭ないしは浸炭および窒化処理後の焼き戻し処理
により、歯車の歯面のかみ合い範囲においては歯面の最
表層の硬度をHv800以上とし、かつ、当該歯車の歯
元すみR部においては最表層の硬度をHv700〜80
0とするようになすことによって、歯面強度をさらに向
上したものとすることが可能であり、歯面の耐ピッチン
グ性および耐摩耗性ならびに歯元の曲げ疲労強度および
耐衝撃性がさらに良好な高強度歯車を製造することが可
能であるという著しく優れた効果がもたらされる。Further, as described in claim 6, the hardness of the outermost layer of the tooth surface is Hv 800 or more in the meshing range of the gear tooth surface by carburizing or tempering after carburizing and nitriding. In addition, the hardness of the outermost layer is Hv700-80 at the root corner R portion of the gear.
By setting to 0, the tooth surface strength can be further improved, and the pitting resistance and wear resistance of the tooth surface and the bending fatigue strength and impact resistance of the tooth root can be further improved. A remarkably excellent effect that a high-strength gear can be manufactured is brought about.
【0046】さらにまた、請求項7に記載しているよう
に、歯元すみR部に必要に応じて希釈した浸炭制御剤を
塗布した後、浸炭処理を行うようになすことによって、
歯元部分での炭素含有量を少ないものとすることがで
き、歯元部分での靭性により優れた高強度歯車を製造す
ることが可能であるという著しく優れた効果がもたらさ
れる。Further, as described in claim 7, the carburizing treatment is carried out after the carburizing control agent diluted as necessary is applied to the root corner R portion.
The carbon content at the root portion can be reduced, and a remarkably excellent effect that a high-strength gear having excellent toughness at the root portion can be manufactured can be obtained.
【0047】さらにまた、請求項8に記載しているよう
に、浸炭処理後に浸炭制御剤を除去し、続いて窒化処理
および2次焼き入れを行うようになすことによって、歯
元部分での窒素量を多いものとして歯元部分での靭性に
より優れた高強度歯車を製造することが可能であるとい
う著しく優れた効果がもたらされる。Further, as described in claim 8, the carburizing control agent is removed after the carburizing treatment, and then the nitriding treatment and the secondary quenching are performed, so that the nitrogen at the tooth root portion is reduced. A remarkably excellent effect is obtained that a high-strength gear having a large amount can be manufactured with higher toughness at the root portion.
【0048】さらにまた、請求項9に記載しているよう
に、200〜250℃にて焼き戻しを行うようになすこ
とによって、歯面硬度を維持すると共に歯元硬度が低下
したものとなって、歯面の耐ピッチング性および耐摩耗
性ならびに歯元の曲げ疲労強度および耐衝撃性がさらに
良好な高強度歯車を製造することが可能であるという著
しく優れた効果がもたらされる。Further, by performing tempering at 200 to 250 ° C., the tooth surface hardness is maintained and the root hardness is reduced. In addition, a remarkably excellent effect is obtained that a high-strength gear having more favorable pitting resistance and wear resistance of the tooth surface as well as bending fatigue strength and impact resistance of the root can be manufactured.
【0049】さらにまた、請求項10に記載しているよ
うに、粒径0.4mm以下の硬質粒子をアークハイト
0.3〜0.8mmとなるように投射するショットピー
ニングを行うようになすことによって、歯車の表面に圧
縮残留応力を付与することが可能であり、疲労強度によ
り一層優れた高強度歯車を製造することが可能であると
いう著しく優れた効果がもたらされる。Still further, according to the present invention, shot peening is performed in which hard particles having a particle size of 0.4 mm or less are projected so as to have an arc height of 0.3 to 0.8 mm. Thereby, it is possible to apply a compressive residual stress to the surface of the gear, and it is possible to manufacture a high-strength gear having more excellent fatigue strength.
【0050】さらにまた、請求項11に記載しているよ
うに、浸炭処理をプラズマ浸炭法により行うようになす
ことによって、真空での処理が行えることから高温下で
あっても粒界酸化を生じず、また、浸炭を迅速におこな
うことが可能であり、品質のよい高強度歯車を生産性よ
く製造することが可能であるという著しく優れた効果が
もたらされる。Furthermore, by performing the carburizing treatment by the plasma carburizing method as described in claim 11, since the treatment can be carried out in a vacuum, grain boundary oxidation occurs even at a high temperature. In addition, carburizing can be performed quickly, and a remarkably excellent effect that high-quality high-strength gears can be manufactured with high productivity can be obtained.
【0051】[0051]
【実施例】素材としてJIS G 4105で制定する
SCM435を用い、歯数12、モジュール4.4のギ
ヤ形状をもつ歯車素材に加工した後、市販の防炭剤を2
/3に希釈しグリセリンにて粘度を調整したものを歯元
R部に塗布した。その後、図5に示す条件で浸炭焼入れ
を行い、防炭剤を除去した後NH3ガス5体積%雰囲気
中で窒化処理し、その後2次焼入れ、高温焼き戻しを行
って本発明実施例の歯車を製造した。EXAMPLE SCM435 specified by JIS G 4105 was used as a material, processed into a gear material having a gear shape having 12 teeth and a module 4.4, and then using a commercially available carbon-proofing agent.
The mixture was diluted to / 3 and the viscosity was adjusted with glycerin. Thereafter, carburizing and quenching is performed under the conditions shown in FIG. 5, and after removing the anti-carbonizing agent, nitriding is performed in an atmosphere of 5% by volume of NH 3 gas, and then secondary quenching and high-temperature tempering are performed to obtain the gear of the present invention. Manufactured.
【0052】比較のために、実施例と同じギヤ形状をも
つ歯車素材に対し図6に示す条件で浸炭・窒化焼き入れ
焼き戻しを行って比較例の歯車を製造した。前記実施例
および比較例で製造した歯車の組織、硬度を調べた結果
を表4に示す。For comparison, a gear material having the same gear shape as in the example was subjected to carburizing, nitriding, quenching and tempering under the conditions shown in FIG. 6 to produce a gear of a comparative example. Table 4 shows the results of examining the structure and hardness of the gears manufactured in the above Examples and Comparative Examples.
【0053】[0053]
【表4】 [Table 4]
【0054】次に、本発明実施例の歯車および比較例の
歯車にショットピーニングを行い、ショット粒径とアー
クハイトが歯先盛り上がりおよび歯元に生じる残留応力
に及ぼす影響を調べた。その結果を表5に示す。Next, the gears of the examples of the present invention and the gears of the comparative example were subjected to shot peening, and the effects of the shot particle size and the arc height on the swelling of the tip and the residual stress generated at the root were examined. Table 5 shows the results.
【0055】[0055]
【表5】 [Table 5]
【0056】表5に示すように、粒径およびアークハイ
トが同じものでは、本発明実施例の歯車に対して比較例
の歯車では歯先盛り上がり量が大きく、また、歯元の圧
縮残留応力ピークも小さい。これは、本発明実施例の歯
車では歯元の残留オーステナイト量が多く、そのため、
ショットピーニングによる加工誘起変態によって高い圧
縮残留応力を生じていることによるものと考えられる。
すなわち、本発明実施例の歯車では歯面の硬度が高く、
かつ、歯元の残留オーステナイト量が多い組織としたた
めに、小径ショットピーニングでも歯元に大きな圧縮残
留応力が得られる。この小径ショットピーニングでは、
大きな歯先盛り上がりが生じないので、その後の修正加
工も少なくてすむ。As shown in Table 5, when the grain size and the arc height were the same, the tooth of the comparative example had a larger amount of swelling at the tooth tip than the gear of the present invention, and the peak of the compressive residual stress at the tooth root. Is also small. This is because the gear of the present invention has a large amount of retained austenite at the tooth root, and therefore,
It is considered that high compressive residual stress is generated by the work induced transformation by shot peening.
That is, in the gear of the embodiment of the present invention, the hardness of the tooth surface is high,
In addition, since the structure has a large amount of retained austenite at the tooth root, a large compressive residual stress can be obtained at the tooth root even with small-diameter shot peening. In this small diameter shot peening,
Since a large tooth tip bulge does not occur, there is less need for subsequent correction processing.
【0057】表5に示す結果から、歯先盛り上がりを抑
えるにはショットの粒径を0.4mm以下とし、アーク
ハイトを0.8mm以下とするのが望ましい。また、ア
ークハイトが0.3mm未満ではショットピーニングの
効果がほとんど得られない。From the results shown in Table 5, it is desirable to set the shot particle diameter to 0.4 mm or less and the arc height to 0.8 mm or less in order to suppress the rise of the tooth tip. When the arc height is less than 0.3 mm, the effect of shot peening is hardly obtained.
【0058】次に、ショットピーニング条件として粒径
が0.4mmの鋼球をアークハイトが0.7mmとなる
ように投射した後、本発明実施例の歯車および比較例の
歯車をトルク4kN−mの歯車かみ合い試験にて評価し
たところ、本発明実施例の歯車の寿命は比較例の歯車に
比べて図7に示すように約4倍程度の破断寿命となっ
た。Next, as a shot peening condition, a steel ball having a particle diameter of 0.4 mm was projected so as to have an arc height of 0.7 mm, and then the gear of the embodiment of the present invention and the gear of the comparative example were torqued to 4 kN-m. As a result, the life of the gear of the example of the present invention was about four times as long as that of the gear of the comparative example as shown in FIG.
【0059】また、ローラーピッチング試験片に本発明
実施例の歯車および比較例の歯車に対して施したのと同
じ熱処理を行い、それぞれの歯面相当の組織および硬度
とし、回転数:1500rpm、滑り率:40%、面
圧:5000MPaにて50%破損寿命を比較した結
果、図8に示すように、本発明相当品の寿命は比較品の
約12倍の長寿命が得られた。Further, the same heat treatment as that performed on the gears of the examples of the present invention and the gears of the comparative examples was performed on the roller pitching test pieces to obtain a structure and hardness corresponding to the respective tooth surfaces. As a result of comparing the 50% failure life at a rate of 40% and a surface pressure of 5000 MPa, as shown in FIG. 8, the life of the product equivalent to the present invention was about 12 times longer than that of the comparison product.
【図1】炭化物の影響を調べる実験で採用した浸炭焼入
れ条件を示す説明図である。FIG. 1 is an explanatory diagram showing carburizing and quenching conditions adopted in an experiment for investigating the effect of carbides.
【図2】300℃焼き戻しを行ったときの表面硬度とロ
ーラーピッチング寿命との関係を表すグラフである。FIG. 2 is a graph showing a relationship between a surface hardness and a roller pitting life when tempering at 300 ° C. is performed.
【図3】浸炭後の窒化の影響を調べる実験で採用した浸
炭および窒化条件を示す説明図である。FIG. 3 is an explanatory diagram showing carburizing and nitriding conditions adopted in an experiment for examining the effect of nitriding after carburizing.
【図4】焼き戻しの影響を調べる実験で採用した熱処理
条件を示す説明図である。FIG. 4 is an explanatory diagram showing heat treatment conditions adopted in an experiment for examining the effect of tempering.
【図5】本発明の実施例で採用した熱処理条件を示す説
明図である。FIG. 5 is an explanatory diagram showing heat treatment conditions adopted in the example of the present invention.
【図6】本発明の比較例で採用した熱処理条件を示す説
明図である。FIG. 6 is an explanatory diagram showing heat treatment conditions adopted in a comparative example of the present invention.
【図7】本発明実施例の歯車と比較例の歯車における疲
労強度を比較した結果を示すグラフである。FIG. 7 is a graph showing the results of comparing the fatigue strength of the gear of the present invention and the gear of the comparative example.
【図8】本発明実施例相当のローラーピッチング試験片
と比較例相当のローラーピッチング試験片についてピッ
チング寿命を比較した結果を示すグラフである。FIG. 8 is a graph showing the results of comparing the pitting life of a roller pitting test piece corresponding to an example of the present invention and a roller pitting test piece corresponding to a comparative example.
フロントページの続き (56)参考文献 特開 平6−25823(JP,A) 特開 平7−316640(JP,A) 特開 平9−72402(JP,A) 特開 平7−242994(JP,A) 特開 平7−3430(JP,A) 特開 平7−54050(JP,A) 特開 昭59−35630(JP,A) 特開 昭63−297866(JP,A) 特開 昭58−189368(JP,A) 特開 平6−17189(JP,A) (58)調査した分野(Int.Cl.7,DB名) F16H 55/00 - 55/56 C21D 1/06 C21D 9/32 C23C 8/20 C23C 8/34 Continuation of front page (56) References JP-A-6-25823 (JP, A) JP-A-7-316640 (JP, A) JP-A-9-72402 (JP, A) JP-A-7-242994 (JP) JP-A-7-3430 (JP, A) JP-A-7-54050 (JP, A) JP-A-59-35630 (JP, A) JP-A-63-297866 (JP, A) 58-189368 (JP, A) JP-A-6-17189 (JP, A) (58) Fields investigated (Int. Cl. 7 , DB name) F16H 55/00-55/56 C21D 1/06 C21D 9 / 32 C23C 8/20 C23C 8/34
Claims (11)
み合い範囲においては歯面の最表層から芯部方向に少な
くとも0.2mmの深さまで面積率で5〜10%の炭化
物が分散析出し、かつ、当該歯車の駆動側および被駆動
側の歯元すみR部においては最表層から芯部にかけての
炭化物が面積率で最大3%であり、かつ、球状ないし擬
球状に分散析出していると共に、窒化処理が施されてい
て、前記かみ合い範囲においては歯面の最表層から芯部
にかけての窒素濃度分布のピークが0.3wt%以下で
あり、前記歯元すみR部においては最表層から芯部にか
けての窒素濃度分布のピークが0.3wt%以上である
ことを特徴とする高強度歯車。1. In the meshing range of the tooth surface on the driving side and the driven side of the gear, 5 to 10% of carbide is dispersed and precipitated at an area ratio from the outermost surface of the tooth surface to a depth of at least 0.2 mm in the direction of the core. In the toothed corners R on the driving side and the driven side of the gear, carbides from the outermost layer to the core have an area ratio of up to 3%, and are dispersed and precipitated in a spherical or pseudospherical shape. In addition, a nitriding treatment has been performed, and in the meshing range, the peak of the nitrogen concentration distribution from the outermost surface layer of the tooth surface to the core portion is 0.3 wt% or less, and the outermost layer in the root portion of the tooth root R is A high-strength gear characterized in that the peak of the nitrogen concentration distribution from the core to the core is 0.3 wt% or more.
面の最表層から芯部にかけての残留オーステナイト量分
布のピークが30wt%以下であり、かつ、当該歯車の
歯元すみR部においては最表層から芯部にかけての残留
オーステナイト量分布のピークが25〜45wt%であ
る請求項1記載の高強度歯車。2. In the meshing range of the gear tooth surface, the peak of the distribution of retained austenite from the outermost layer of the tooth surface to the core is 30 wt% or less, and the peak of the tooth root radius R portion of the gear is the lowest. 2. The high-strength gear according to claim 1, wherein the peak of the distribution of the retained austenite amount from the surface layer to the core portion is 25 to 45 wt%.
面の最表層の硬度がHv800以上であり、かつ、当該
歯車の歯元すみR部においては最表層の硬度がHv70
0〜800である請求項1または2に記載の高強度歯
車。3. The hardness of the outermost layer of the tooth surface is Hv800 or more in the meshing range of the tooth surface of the gear, and the hardness of the outermost layer is Hv70 in the tooth corner radius R portion of the gear.
The high-strength gear according to claim 1, wherein the number is from 0 to 800. 4.
却および加熱処理を施して炭化物を析出させたあと窒化
処理を施すことにより、歯車の駆動側および被駆動側の
歯面のかみ合い範囲においては歯面の最表層から芯部方
向に少なくとも0.2mmの深さまで面積率で5〜10
%の炭化物を分散析出させ、かつ、当該歯車の駆動側お
よび被駆動側の歯元すみR部においては最表層から芯部
にかけての炭化物を面積率で最大3%とし、かつ、球状
ないし擬球状に分散析出させると共に、前記かみ合い範
囲においては歯面の最表層から芯部にかけての窒素濃度
分布のピークを0.3wt%以下とし、前記歯元すみR
部においては最表層から芯部にかけての窒素濃度分布の
ピークを0.3wt%以上とすることを特徴とする高強
度歯車の製造方法。4. Carburizing treatment of the gear material, followed by cooling or cooling and heating treatment to precipitate carbides and then nitriding treatment, so that the gears can be engaged in the meshing range of the tooth surfaces on the driving side and the driven side of the gear. 5 to 10 at an area ratio from the outermost layer of the surface to a depth of at least 0.2 mm in the direction of the core.
% Of carbide is dispersed and precipitated, and in the tooth corner R at the driving side and the driven side of the gear, the carbide from the outermost layer to the core is made up to 3% in area ratio, and is spherical or pseudo spherical. In the meshing range, the peak of the nitrogen concentration distribution from the outermost surface layer of the tooth surface to the core is set to 0.3 wt% or less, and the tooth root radius R is reduced.
A method for producing a high-strength gear, wherein a peak of a nitrogen concentration distribution from the outermost layer to the core is 0.3 wt% or more in a portion.
面の最表層から芯部にかけての残留オーステナイト量分
布のピークを30wt%以下とし、かつ、当該歯車の歯
元すみR部においては最表層から芯部にかけての残留オ
ーステナイト量分布のピークを25〜45wt%とする
請求項4に記載の高強度歯車の製造方法。5. The peak of the distribution of residual austenite from the outermost layer of the tooth surface to the core in the meshing range of the tooth surface of the gear is 30 wt% or less, and the outermost layer is formed at the root portion R of the tooth root. The method for manufacturing a high-strength gear according to claim 4, wherein the peak of the distribution of the amount of retained austenite from the core to the core is 25 to 45 wt%.
き戻し処理により、歯車の歯面のかみ合い範囲において
は歯面の最表層の硬度をHv800以上とし、かつ、当
該歯車の歯元すみR部においては最表層の硬度をHv7
00〜800とする請求項4または5に記載の高強度歯
車の製造方法。6. Carburizing or tempering after carburizing and nitriding, the hardness of the outermost surface of the tooth surface is set to Hv800 or more in the meshing range of the tooth surface of the gear, and at the root portion R of the tooth root of the gear. Indicates the hardness of the outermost layer is Hv7
The method for manufacturing a high-strength gear according to claim 4 or 5, wherein the number is from 00 to 800.
後、浸炭処理を行う請求項4ないし6のいずれかに記載
の高強度歯車の製造方法。7. The method for producing a high-strength gear according to claim 4, wherein a carburizing treatment is performed after the carburizing control agent is applied to the root corner R.
て窒化処理および2次焼き入れを行う請求項7に記載の
高強度歯車の製造方法。8. The method for manufacturing a high-strength gear according to claim 7, wherein the carburizing control agent is removed after the carburizing treatment, and then the nitriding treatment and the secondary quenching are performed.
求項4ないし8のいずれかに記載の高強度歯車の製造方
法。9. The method for producing a high-strength gear according to claim 4, wherein the tempering is performed at 200 to 250 ° C.
クハイト0.3〜0.8mmとなるように投射するショ
ットピーニングを行う請求項4ないし9のいずれかに記
載の高強度歯車の製造方法。10. The production of a high-strength gear according to claim 4, wherein shot peening is performed by projecting hard particles having a particle diameter of 0.4 mm or less so as to have an arc height of 0.3 to 0.8 mm. Method.
請求項4ないし10のいずれかに記載の高強度歯車の製
造方法。11. The method for producing a high-strength gear according to claim 4, wherein the carburizing treatment is performed by a plasma carburizing method.
Priority Applications (1)
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JP18281198A JP3271659B2 (en) | 1998-06-29 | 1998-06-29 | High strength gear and manufacturing method thereof |
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JP18281198A JP3271659B2 (en) | 1998-06-29 | 1998-06-29 | High strength gear and manufacturing method thereof |
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JP2000018369A JP2000018369A (en) | 2000-01-18 |
JP3271659B2 true JP3271659B2 (en) | 2002-04-02 |
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JP18281198A Expired - Fee Related JP3271659B2 (en) | 1998-06-29 | 1998-06-29 | High strength gear and manufacturing method thereof |
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Cited By (1)
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JP7524161B2 (en) | 2019-04-05 | 2024-07-29 | 三菱電機株式会社 | Refrigeration Cycle Equipment |
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Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP3620707B2 (en) * | 2000-05-19 | 2005-02-16 | 日産自動車株式会社 | Rolling element for continuously variable transmission |
JP4662205B2 (en) * | 2005-06-13 | 2011-03-30 | 新東工業株式会社 | Shot peening processing method |
JP2010222636A (en) * | 2009-03-23 | 2010-10-07 | Aisin Seiki Co Ltd | Surface treatment method of steel product |
JP5548920B2 (en) * | 2009-12-02 | 2014-07-16 | パーカー熱処理工業株式会社 | Method for carburizing a workpiece having an edge |
WO2022123715A1 (en) | 2020-12-10 | 2022-06-16 | 公益財団法人応用科学研究所 | Gear and manufacturing method therefor |
WO2023182333A1 (en) * | 2022-03-25 | 2023-09-28 | 日立建機株式会社 | Gear component |
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1998
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Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
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JP7524161B2 (en) | 2019-04-05 | 2024-07-29 | 三菱電機株式会社 | Refrigeration Cycle Equipment |
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