JP3033638B2 - Methods for improving the fatigue strength of carburized and hardened parts - Google Patents
Methods for improving the fatigue strength of carburized and hardened partsInfo
- Publication number
- JP3033638B2 JP3033638B2 JP04162380A JP16238092A JP3033638B2 JP 3033638 B2 JP3033638 B2 JP 3033638B2 JP 04162380 A JP04162380 A JP 04162380A JP 16238092 A JP16238092 A JP 16238092A JP 3033638 B2 JP3033638 B2 JP 3033638B2
- Authority
- JP
- Japan
- Prior art keywords
- carburized
- shot
- fatigue strength
- quenched
- improving
- 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 - Lifetime
Links
Landscapes
- Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)
- Heat Treatment Of Articles (AREA)
Description
【０００１】[0001]
【産業上の利用分野】本発明は、自動車の駆動系等に用
いられる浸炭焼入れ部品の疲労強度を向上させる方法に
関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for improving the fatigue strength of a carburized and quenched part used for a drive system of an automobile.
【０００２】[0002]
【従来の技術】一般に、自動車の駆動系（トランスミッ
ション、デイファレンシャル等）に用いられる動力伝達
軸においては、一般機械の動力伝達軸よりも高い動力の
伝達を要求されるので、必要な耐磨耗性および疲労強度
を与えるために浸炭焼入れを行う。尚、浸炭焼入れ法と
しては、固体浸炭焼入れ、液体浸炭焼入れもあるが、大
量生産に適し、品質の安定が維持できることから、ガス
浸炭焼入れが主流となっている。2. Description of the Related Art Generally, a power transmission shaft used for a drive system of an automobile (transmission, differential, etc.) is required to transmit a higher power than a power transmission shaft of a general machine. Carburize and quench to provide wear and fatigue strength. The carburizing and quenching methods include solid carburizing and quenching, and liquid carburizing and quenching. However, gas carburizing and quenching are the mainstream because they are suitable for mass production and can maintain stable quality.
【０００３】ところで、上記浸炭焼入れの結果、耐磨耗
性の点から必要な表面かたさは比較的容易に得られる
が、ガス浸炭焼入れのため、雰囲気ガス中のＣＯ2 、Ｈ
2 、微量に存在しているＯ2 などが、軸材に添加されて
いるＣｒ、Ｍｎ、Ｓｉ、Ａｌ、Ｂなどの元素に対して酸
化雰囲気となり、このため、浸炭処理中に、これらの元
素が表面付近で結晶粒界に沿って内部酸化し、表面の焼
入れ性を低下させて最表面に異常層と呼ばれる不完全焼
入れ層が生成し、強度低下を招いていた。Meanwhile, the result of the carburizing and quenching, but the necessary surface hardness from the viewpoint of abrasion resistance obtained relatively easily, for gas carburizing and quenching, in the atmospheric gas CO 2, H
2. O 2 and the like present in trace amounts become an oxidizing atmosphere for elements such as Cr, Mn, Si, Al, and B added to the shaft material. Was internally oxidized along the crystal grain boundaries near the surface, degrading the hardenability of the surface, producing an incompletely hardened layer called an abnormal layer on the outermost surface, leading to a decrease in strength.
【０００４】そこで、上記表面異常層を改善する方法と
して種々試みがなされているが、ショットピーニングを
行うことにより著しい強度向上が得られることが判り、
近年、自動車用浸炭焼入れ部品の表面硬化処理として多
用されている。即ち、浸炭焼入れ後、ショットピーニン
グを行うと、表面層の残留オーステナイトが加工硬化す
ることによりマルテンサイト化され、そのため、圧縮残
留応力が付与される。これにより、疲労強度を向上させ
る。Various attempts have been made to improve the surface abnormal layer. However, it has been found that a remarkable improvement in strength can be obtained by performing shot peening.
In recent years, it is frequently used as a surface hardening treatment for carburized and hardened parts for automobiles. That is, when shot peening is performed after carburizing and quenching, the retained austenite in the surface layer is work-hardened to form martensite, and thus compressive residual stress is applied. Thereby, the fatigue strength is improved.
【０００５】[0005]
【発明が解決しようとする課題】ところで、従来は表面
硬度の上昇および圧縮残留応力の付与のためにショット
ピーニングを行っているが、これだけでは疲労強度向上
が十分ではない。即ち、従来はショットピーニングによ
り大きな圧縮残留応力を付与するため、直径 0.4mmクラ
ス以上の大きなボールを表面にショットさせていたが、
これでは表面粗度が悪化して疲労強度を十分に向上させ
ることができない。しかも、圧縮残留応力は疲労の進展
を抑える役割しかなく、表面異常層に疲労亀裂が発生す
ると、いくら圧縮残留応力が高くても破損は避け難い。
従って、浸炭焼入れ部品の疲労強度を向上するには、大
きな圧縮残留応力の付与も大切であるが、表面粗度の向
上および表面異常層を無くすることが重要である。Conventionally, shot peening has been performed to increase the surface hardness and impart compressive residual stress, but this alone is not sufficient to improve the fatigue strength . That is, conventionally, a large ball with a diameter of 0.4 mm or more was shot on the surface in order to give a large compressive residual stress by shot peening.
In this case, the surface roughness deteriorates and the fatigue strength cannot be sufficiently improved. Moreover, the compressive residual stress only plays a role of suppressing the progress of fatigue, and if a fatigue crack occurs in the abnormal surface layer, it is difficult to avoid breakage even if the compressive residual stress is high.
Therefore, in order to improve the fatigue strength of a carburized and quenched part, it is important to apply a large compressive residual stress, but it is important to improve the surface roughness and eliminate the abnormal surface layer.
【０００６】本発明はこのような問題に鑑みてなされた
もので、浸炭焼入れ部品の疲労強度をより一層向上させ
る方法を提供することを目的とする。[0006] The present invention has been made in view of such a problem, and an object of the present invention is to provide a method for further improving the fatigue strength of a carburized and quenched part.
【０００７】[0007]
【課題を解決するための手段】本発明は上記目的を達成
するため、表面異常層を有する浸炭焼入れ部品に対して
直径０．１mm以下の小さなショット玉を用いてショット
ピーニングを施し、上記浸炭焼入れ部品に圧縮残留応力
を付与するとともに、当該部品の表面異常層をマルテン
サイトに変態させて当該表面異常層を無くすようにした
浸炭焼入れ部品の疲労強度向上方法を提供する。According to the present invention, in order to achieve the above object, a carburized and quenched part having an abnormal surface layer is subjected to shot peening using a small shot ball having a diameter of 0.1 mm or less, and Provided is a method for improving the fatigue strength of a carburized and quenched component in which a compressive residual stress is applied to a component and the abnormal surface layer of the component is transformed into martensite to eliminate the abnormal surface layer.
【０００８】[0008]
【作用】本発明によれば、表面異常層を有する浸炭焼入
れ部品に対して直径 0.1mm以下の小さなショット玉を用
いてショットピーニングを施すことにより、表面粗度を
悪化させることなく浸炭焼入れ部品にある程度の圧縮残
留応力が付与される。しかも、ショットピーニング時に
発生する熱により浸炭焼入れ部品に再び焼きが入り、こ
れにより表面異常層をマルテンサイトに変態させて当該
表面異常層をなくせれる。According to the present invention, a carburized and quenched component having an abnormal surface layer is subjected to shot peening using a small shot ball having a diameter of 0.1 mm or less, so that a carburized and quenched component can be obtained without deteriorating surface roughness. Some compressive residual stress is applied. In addition, the carburized and quenched part is again quenched by the heat generated during shot peening, thereby transforming the abnormal surface layer into martensite and eliminating the abnormal surface layer.
【０００９】[0009]
【実施例】以下、本発明に係る浸炭焼入れ部品の疲労強
度向上方法を図面に基づいて説明する。DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for improving the fatigue strength of a carburized and quenched part according to the present invention will be described below with reference to the drawings.
【００１０】図１は本発明方法で使用する玉ショット装
置を示し、加圧タンク（１）内に多数の直径 0.1mm以下
の小さなショット玉（２）（２）…を収容し、これをシ
ョットノズル（３）の先端からエアー圧力で噴射する。FIG. 1 shows a ball shot apparatus used in the method of the present invention. A large number of small shot balls (2) (2)... Injection is performed with air pressure from the tip of the nozzle (3).
【００１１】本発明方法は上記玉ショット装置により加
圧タンク（１）内の多数の直径 0.1mm以下の小さなショ
ット玉（２）（２）…をショットノズル（３）の先端か
ら噴射し、これを浸炭焼入れ部品の一例である動力伝達
軸（４）にショットさせる。尚、この実施例における動
力伝達軸（４）は、例えばトランスミッションのインプ
ットシャフト或いはアウトプットシャフトとして用いら
れるもので、軸上に歯車（４ａ）およびスプライン（４
ｂ）が一体に形成してあり、この歯車（４ａ）およびス
プライン（４ｂ）を含めた全体にショット玉（２）
（２）…をショットさせる。According to the method of the present invention, a large number of small shot balls (2) (2)... Having a diameter of 0.1 mm or less in a pressurized tank (1) are jetted from the tip of a shot nozzle (3) by the ball shot device. Is shot on a power transmission shaft (4) which is an example of a carburized and quenched part. The power transmission shaft (4) in this embodiment is used as, for example, an input shaft or an output shaft of a transmission, and has a gear (4a) and a spline (4) on the shaft.
b) is integrally formed, and the shot ball (2) is entirely formed including the gear (4a) and the spline (4b).
(2) ... is shot.
【００１２】本発明に係る方法によれば、直径０．１mm
以下の小さなショット玉（２）を動力伝達軸（４）にシ
ョットさせることにより、表面粗度を悪化させることな
く動力伝達軸（４）にある程度の圧縮残留応力が付与さ
れる。しかも、直径０．１mm以下の小さなショット玉
（２）を動力伝達軸（４）にショットさせると、ショッ
ト時にショット玉（２）と動力伝達軸（４）との間に摩
擦熱が発生し、この摩擦熱はショット玉（２）が小さい
ために動力伝達軸（４）に多く伝導され、これにより動
力伝達軸（４）に焼きが入り、図２に示すように、不完
全焼入れ層である表面異常層（ａ）がマルテンサイト
（ｂ）に変態して当該表面異常層（ａ）を無くすことが
できた。According to the method of the present invention, the diameter is 0.1 mm.
By making the following small shot balls (2) shot on the power transmission shaft (4), a certain degree of compressive residual stress is applied to the power transmission shaft (4) without deteriorating the surface roughness. Moreover, when a small shot ball (2) having a diameter of 0.1 mm or less is shot on the power transmission shaft (4), frictional heat is generated between the shot ball (2) and the power transmission shaft (4) during the shot, This frictional heat is largely transmitted to the power transmission shaft (4) due to the small shot ball (2), thereby quenching the power transmission shaft (4), and as shown in FIG. 2, it is an incompletely quenched layer. The abnormal surface layer (a) was transformed into martensite (b), and the abnormal surface layer (a) could be eliminated.
【００１３】従って、本発明に係る方法によれば、表面
粗度を悪化させることなく動力伝達軸（４）に圧縮残留
応力を付与させるとともに、疲労亀裂が発生し易い表面
異常層を無くせれるから、動力伝達軸（４）の疲労強度
を著しく向上させることが可能である。Therefore, according to the method of the present invention, it is possible to impart a compressive residual stress to the power transmission shaft (4) without deteriorating the surface roughness, and to eliminate an abnormal surface layer where fatigue cracks are easily generated. Thus, the fatigue strength of the power transmission shaft (4) can be significantly improved.
【００１４】尚、大きな圧縮残留応力を付与させたい場
合は、大きなショット玉をショットさせた後、直径 0.1
mm以下の小さなショット玉をショットさせる２段ショッ
トを行えば良い。When it is desired to apply a large compressive residual stress, a large shot ball is shot, and then a diameter of 0.1 mm is applied.
What is necessary is just to perform a two-step shot in which a small shot ball of mm or less is shot.
【００１５】また、本発明は浸炭焼入れ歯車単体やその
他の浸炭焼入れ部品にも適用し得ることは言うまでもな
い。It is needless to say that the present invention can be applied to a carburized and quenched gear alone and other carburized and quenched parts.
【００１６】[0016]
【発明の効果】 以上説明したように、本発明は、表面異
常層を有する浸炭焼入れ部品に対して直径０．１mm以下
の小さなショット玉を用いてショットピーニングを施す
ことにより、表面粗度を悪化させることなく浸炭焼入れ
部品に圧縮残留応力を付与させるとともに、疲労亀裂が
発生し易い表面異常層をマルテンサイトに変態させて当
該表面異常層を無くせれるから、浸炭焼入れ部品の疲労
強度を著しく向上させることができる。 As described above, according to the present invention, carburized and quenched parts having an abnormal surface layer are subjected to shot peening using small shot balls having a diameter of 0.1 mm or less, thereby deteriorating the surface roughness. While imparting compressive residual stress to the carburized and quenched part without causing it, and transforming the abnormal surface layer where fatigue cracks easily occur into martensite and eliminating the abnormal surface layer, the fatigue strength of the carburized and quenched part is significantly improved. be able to.
【図１】本発明に係る浸炭焼入れ部品の疲労強度向上方
法に使用する玉ショット装置の概略図である。FIG. 1 is a schematic view of a ball shot device used in a method for improving the fatigue strength of a carburized and quenched part according to the present invention.
【図２】浸炭焼入れ部品の表面断面の処理前と処理後の
金属組織図である。FIG. 2 is a metallographic view of a surface section of a carburized and quenched part before and after processing.
１ 加圧タンク ２ ショット玉 ３ ショットノズル ４ 動力伝達軸（浸炭焼入れ部品） ａ 表面異常層 ｂ マルテンサイト Reference Signs List 1 pressurized tank 2 shot ball 3 shot nozzle 4 power transmission shaft (carburized and quenched parts) a abnormal surface layer b martensite
───────────────────────────────────────────────────── フロントページの続き (72)発明者 垪和 成佳 大阪府池田市桃園２丁目１番１号 ダイ ハツ工業株式会社内 (72)発明者 相田 和俊 大阪府池田市桃園２丁目１番１号 ダイ ハツ工業株式会社内 (72)発明者 宮坂 四志男 愛知県名古屋市北区丸新町471番地 株 式会社不二機販内 (56)参考文献 特開 昭61−265271（ＪＰ，Ａ) 特開 平２−301513（ＪＰ，Ａ) 特開 平４−13573（ＪＰ，Ａ) 特開 昭62−253723（ＪＰ，Ａ) 特公 平２−17607（ＪＰ，Ｂ２) (58)調査した分野(Int.Cl.7，ＤＢ名) B24C 1/10 C21D 7/06 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Narika Shigeka 2-1-1, Taoyuan, Ikeda-shi, Osaka Inside Dai-Hatsu Kogyo Co., Ltd. (72) Kazutoshi Aida 2-1-1 Taoyuan, Ikeda-shi, Osaka Dai-Hatsu Kogyo Co., Ltd. (72) Inventor Shizio Miyasaka 471 Marushinmachi, Kita-ku, Nagoya City, Aichi Prefecture Fuji Machine Sales Co., Ltd. (56) References JP-A-61-265271 (JP, A) JP-A-2-301513 (JP, A) JP-A-4-13573 (JP, A) JP-A-62-253723 (JP, A) JP-B-2-17607 (JP, B2) (58) Int.Cl. 7 , DB name) B24C 1/10 C21D 7/06
Claims (1)
して直径０．１mm以下の小さなショット玉を用いてショ
ットピーニングを施し、上記浸炭焼入れ部品に圧縮残留
応力を付与するとともに、当該部品の表面異常層をマル
テンサイトに変態させて当該表面異常層を無くすように
したことを特徴とする浸炭焼入れ部品の疲労強度向上方
法。1. A carburized and quenched part having an abnormal surface layer is subjected to shot peening using a small shot ball having a diameter of 0.1 mm or less to impart a compressive residual stress to the carburized and quenched part and to provide a surface of the part. A method for improving the fatigue strength of a carburized and quenched part, wherein the abnormal layer is transformed into martensite to eliminate the surface abnormal layer.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3-267987 | 1991-10-17 | ||
| JP26798791 | 1991-10-17 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH05301165A JPH05301165A (en) | 1993-11-16 |
| JP3033638B2 true JP3033638B2 (en) | 2000-04-17 |
Family
ID=17452341
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP04162380A Expired - Lifetime JP3033638B2 (en) | 1991-10-17 | 1992-06-22 | Methods for improving the fatigue strength of carburized and hardened parts |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3033638B2 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3355275B2 (en) * | 1996-03-08 | 2002-12-09 | 本田技研工業株式会社 | Gear strengthening device |
| JP2002188702A (en) | 2000-12-25 | 2002-07-05 | Nissan Motor Co Ltd | Rolling element for continuously variable transmission and its manufacturing method |
| KR101134422B1 (en) * | 2009-10-29 | 2012-04-09 | 현대 파워텍 주식회사 | Moving part for automatic transmission and method for surface treatment thereof |
-
1992
- 1992-06-22 JP JP04162380A patent/JP3033638B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH05301165A (en) | 1993-11-16 |
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