JP3182957B2 - Gear carburizing method - Google Patents
Gear carburizing methodInfo
- Publication number
- JP3182957B2 JP3182957B2 JP00511693A JP511693A JP3182957B2 JP 3182957 B2 JP3182957 B2 JP 3182957B2 JP 00511693 A JP00511693 A JP 00511693A JP 511693 A JP511693 A JP 511693A JP 3182957 B2 JP3182957 B2 JP 3182957B2
- Authority
- JP
- Japan
- Prior art keywords
- carburizing
- tooth
- gear
- root portion
- plasma
- 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
- 238000005255 carburizing Methods 0.000 title claims description 42
- 238000000034 method Methods 0.000 title claims description 27
- 239000000463 material Substances 0.000 claims description 10
- 229910001566 austenite Inorganic materials 0.000 claims description 5
- 230000000717 retained effect Effects 0.000 claims description 5
- 229910000734 martensite Inorganic materials 0.000 claims description 4
- 229910000831 Steel Inorganic materials 0.000 description 12
- 239000010959 steel Substances 0.000 description 12
- 238000011282 treatment Methods 0.000 description 12
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 7
- 229910052799 carbon Inorganic materials 0.000 description 7
- 230000000694 effects Effects 0.000 description 3
- 230000002265 prevention Effects 0.000 description 3
- 229910003296 Ni-Mo Inorganic materials 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 238000005520 cutting process Methods 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- DDTIGTPWGISMKL-UHFFFAOYSA-N molybdenum nickel Chemical compound [Ni].[Mo] DDTIGTPWGISMKL-UHFFFAOYSA-N 0.000 description 2
- 239000002244 precipitate Substances 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 238000010791 quenching Methods 0.000 description 2
- 230000000171 quenching effect Effects 0.000 description 2
- 229910018487 Ni—Cr Inorganic materials 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 239000012141 concentrate Substances 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000009832 plasma treatment Methods 0.000 description 1
- 238000007747 plating Methods 0.000 description 1
- 230000001681 protective effect Effects 0.000 description 1
- 238000005496 tempering Methods 0.000 description 1
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】この発明は、歯車の浸炭処理法に
関し、とくに耐ピッティング性や歯元疲労強度などの歯
車特性の有利な向上を、生産能率の向上に併せて実現し
ようとするものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of carburizing a gear, and more particularly to an advantageous improvement of gear characteristics such as pitting resistance and tooth root fatigue strength, together with an improvement in production efficiency. It is.
【０００２】[0002]
【従来の技術】自動車や建設機械用の歯車としては、高
強度のみならず、とくに耐ピッティング性が必要とされ
るため、従来から浸炭処理を施して歯面硬度を向上させ
た浸炭歯車が用いられている。しかしながら、歯車全体
に一様に浸炭処理を施した場合には、歯面の硬度は上昇
するものの、歯元部ではかえって疲労強度が低下し、耐
衝撃性が劣化する。そこで、歯元部の疲労強度を低下さ
せることなしに、歯面の耐ピッティング性を向上させる
方法として、例えば特開昭63−297866号公報では、歯元
Ｒ部や歯底部に防炭処理たとえば防炭材の塗布を行った
上で、表面Ｃポテンシャルを高めに設定した条件で浸炭
処理を行う方法が提案されている。2. Description of the Related Art Car gears for automobiles and construction machines require not only high strength but also especially pitting resistance. Therefore, carburized gears which have been subjected to carburizing treatment to improve tooth surface hardness have been conventionally used. Used. However, when the entire gear is uniformly carburized, the hardness of the tooth surface is increased, but the fatigue strength is rather reduced at the base of the tooth, and the impact resistance is deteriorated. Therefore, as a method of improving the pitting resistance of the tooth surface without lowering the fatigue strength of the tooth root, for example, in Japanese Patent Application Laid-Open No. 63-297866, a carbon-proof treatment is applied to the root R and the tooth bottom. For example, a method has been proposed in which a carburizing material is applied and then carburizing is performed under conditions in which the surface C potential is set higher.
【０００３】ここに防炭処理法としては、めっき法、防
炭材ハケ塗り法及び防炭シール貼付法などを利用した方
法がある。また、防炭材を薄めて、歯底部のＣ量をコン
トロールする方法などもある。[0003] As the carbon prevention treatment method, there are methods using a plating method, a carbon protection material brush coating method, a carbon protection seal sticking method, and the like. In addition, there is a method of controlling the amount of carbon at the bottom of the tooth by thinning the carbon protective material.
【０００４】[0004]
【発明が解決しようとする課題】しかしながら、上記よ
うな防炭処理法は、防炭材の塗布及び浸炭後の除去に長
時間を要するだけでなく、特に塗布作業には熟練を必要
とするところに問題を残していた。また、上記の各方法
を採用してもなお、歯元疲労強度が依然として低いとこ
ろにも問題があった。この発明は、上記の問題を有利に
解決するもので、生産性を阻害することなしに、耐ピッ
ティング性はいうまでもなく、歯元疲労強度を効果的に
向上させ得る、歯車の新規な浸炭処理法を提案すること
を目的とする。However, the above-mentioned carbon-prevention treatment requires not only a long time for applying the carbon-proof material and removing it after carburizing, but also requires a special skill for the coating operation. Had left the problem. Further, even when each of the above methods is adopted, there is a problem in that the root fatigue strength is still low. The present invention advantageously solves the above-described problems, and without impairing productivity, not only pitting resistance, but also a new gear gear that can effectively improve root fatigue strength. The purpose is to propose a carburizing method.
【０００５】[0005]
【課題を解決するための手段】さて発明者らは、上記の
目的を達成すべく、数多くの実験と検討を重ねたが、そ
の過程で、浸炭法としてプラズマ浸炭法の利用を試みた
ところ、所期した目的の達成に関し、望外の成果が得ら
れたのである。また、プラズマ浸炭法による浸炭処理の
際、歯元Ｒ部及び歯底部のみに近接する防炭治具を利用
すれば、一層優れた効果が得られることも併せて見出し
た。この発明は、上記の知見に立脚するものである。Means for Solving the Problems The inventors of the present invention have conducted numerous experiments and studies in order to achieve the above-mentioned object. In the course of the experiment, the inventors tried to use the plasma carburizing method as a carburizing method. Unexpected results were achieved in achieving the desired objectives. It has also been found that, when carburizing by the plasma carburizing method, a more excellent effect can be obtained by using a carburizing jig close to only the root portion and the root portion. The present invention is based on the above findings.
【０００６】すなわちこの発明は、所定の形状に仕上げ
た歯車に浸炭処理を施すに当たり、プラズマ浸炭法を用
い、歯面には炭化物を析出させる一方、歯元Ｒ部及び歯
底部は（マルテンサイト＋残留オーステナイト）組織と
することを特徴とする歯車の浸炭処理法である。That is, according to the present invention, when carburizing a gear finished in a predetermined shape, a plasma carburizing method is used to precipitate carbide on the tooth surface, while the root portion of the root and the tooth bottom are formed of (martensite + This is a method of carburizing a gear, which has a retained austenite) structure.
【０００７】この発明では、歯元Ｒ部及び歯底部のみを
遮蔽する防炭治具の存在下にプラズマ浸炭処理を施すこ
とがとりわけ有利である。また、効果の一層の向上を図
るためには、歯車素材中に、Ni及びMoを複合含有させる
ことがより好ましい。In the present invention, it is particularly advantageous to carry out the plasma carburizing treatment in the presence of a carburizing jig for shielding only the root portion and the tooth bottom. In addition, in order to further improve the effect, it is more preferable that Ni and Mo are compounded in the gear material.
【０００８】[0008]
【作用】この発明によれば、多大の時間を要していた防
炭材の塗布及び除去作業が不要となるので、生産性が格
段に向上するだけでなく、プラズマ浸炭法を利用した場
合には、歯面部にグロー放電が集中するため炭化物が析
出するのは歯面だけで、歯元Ｒ部及び歯底部は（マルテ
ンサイト＋残留オーステナイト）組織となるので、歯面
の耐ピッティング性は言うまでもなく、歯元部の疲労強
度が格段に向上する。According to the present invention, it is not necessary to apply and remove the carbon-blocking material, which requires a lot of time, so that not only the productivity is remarkably improved, but also when the plasma carburizing method is used. Because the glow discharge concentrates on the tooth surface, carbide precipitates only on the tooth surface, and the root portion and the root of the tooth have a (martensite + retained austenite) structure. Needless to say, the fatigue strength at the base of the tooth is significantly improved.
【０００９】この発明では、プラズマ浸炭処理によっ
て、歯面の表面Ｃ量を増大して、耐ピッティング性の向
上を図るわけであるが、このとき表面硬度はＨRC≧61、
また有効硬化層深さ≧１mmとすることが好ましい。ここ
に、上記の表面硬度及び有効硬化層深さを得るには、以
下の条件でプラズマ処理を行えば良い。たとえば、浸炭
温度：960 ℃、表面Ｃ量：1.5 wt％、浸炭時間：2.5
ｈ、焼入れ温度：870 ℃、焼入れ油温：80℃、そして焼
戻し処理：170 ℃×２ｈ後、空冷である。なお、プラズ
マ浸炭処理に要する時間は２〜４時間程度であるので、
従来のガス浸炭法に較べると、所要時間が大幅に短縮さ
れる。In the present invention, the amount of surface C of the tooth surface is increased by plasma carburization to improve the pitting resistance. At this time, the surface hardness is HRC ≧ 61,
Further, it is preferable that the effective hardened layer depth ≧ 1 mm. Here, in order to obtain the above surface hardness and effective hardened layer depth, plasma treatment may be performed under the following conditions. For example, carburizing temperature: 960 ° C, surface C content: 1.5 wt%, carburizing time: 2.5
h, quenching temperature: 870 ° C., quenching oil temperature: 80 ° C., tempering treatment: 170 ° C. × 2 hours, and then air cooling. In addition, since the time required for the plasma carburizing treatment is about 2 to 4 hours,
The required time is greatly reduced as compared with the conventional gas carburizing method.
【００１０】またこの発明に従うプラズマ浸炭処理の実
施に際して、歯元Ｒ部及び歯底部のみに近接する防炭治
具を利用すれば、歯元Ｒ部及び歯底部の浸炭をほぼ完全
に防止することができるので、歯元部疲労強度の一層の
向上を図ることができる。ここにかような防炭治具とし
ては、図２（ｂ）に示すようなものが、とりわけ有利に
適合する。In carrying out the plasma carburizing treatment according to the present invention, the use of a carburizing jig close to only the root portion and the root portion makes it possible to substantially completely prevent carburization of the root portion and the root portion. Therefore, the root fatigue strength can be further improved. As such a coal-proof jig, the one shown in FIG. 2B is particularly advantageously applied.
【００１１】さらにこの発明では、歯車素材中に、Ni及
びMoを併せて含有させることが有利である。というの
は、Ni及びMoを複合含有させた場合には、焼入れ性が向
上し、表面及び内部の硬さが向上すると共に、靭性も向
上するので、耐ピッティング性及び歯元疲労強度ともに
一層の向上が望み得るからである。ここに上記の効果を
得るためには好適なNi, Mo量はそれぞれ、Ni：0.5 〜2.
5wt％（以下単に％で示す）、Mo：0.1 〜1.0 ％程度で
ある。Further, in the present invention, it is advantageous to include Ni and Mo together in the gear material. This is because, when Ni and Mo are combined, the hardenability is improved, the surface and internal hardness are improved, and the toughness is also improved, so both the pitting resistance and the root fatigue strength are further improved. This is because an improvement in can be expected. Here, in order to obtain the above-mentioned effects, preferable amounts of Ni and Mo are respectively Ni: 0.5 to 2.
5 wt% (hereinafter simply indicated as%), Mo: about 0.1 to 1.0%.
【００１２】なお、この発明における歯車用鋼素材とし
ては、上述したとおり、Ni, Mo複合添加鋼がとりわけ有
利に適合するけれども、これだけに限られるものではな
く、以下に示すような機械構造用鋼であればいずれもが
適合する。 ・Cr鋼：SCr 415, SCr 420など。 ・Cr−Mo鋼：SCM 415, SCM 420, SCM 421 など。 ・Ni−Cr鋼：SNC 415, SNC 815など。 ・Ni−Cr−Mo鋼：SNCM 220, SNCM 415, SNCM 420など。As described above, the steel material for gears according to the present invention is particularly preferably Ni-, Mo-composite-added steel, but is not limited thereto. If both are suitable.・ Cr steel: SCr 415, SCr 420, etc.・ Cr-Mo steel: SCM415, SCM420, SCM421 etc.・ Ni-Cr steel: SNC 415, SNC 815, etc.・ Ni-Cr-Mo steel: SNCM 220, SNCM 415, SNCM 420, etc.
【００１３】[0013]
【実施例】表１に成分組成を示す供試鋼（鋼：SCM42
0、鋼：Ni−Mo添加鋼）をそれぞれ、表２に示す歯車
諸元（平歯）に従って機械加工した後、図１（ａ）〜
（ｄ）に示す浸炭条件および拡散条件で浸炭処理を施し
た。このとき一部については、図２（ａ），（ｂ）に示
すような防炭処理を施した。なお図１に示した浸炭処理
は、同図ａのガス浸炭処理および同図ｂ〜ｄのプラズマ
浸炭処理とも、浸炭後の表面Ｃ量が 1.5％となる条件で
行った。また同図ｂ〜ｄのプラズマ浸炭については、歯
車を陰極とし、周囲に陽極板を配置して行った。防炭治
具を使用した場合には、これも陰極（補助陰極）とし
た。また雰囲気は、３Torrの（H2＋CH4)雰囲気とし、こ
のうち CH4分圧は 0.8Torrとした。表３に浸炭処理条件
を示す。また表４には、得られた製品の表面硬度、炭化
物面積率、有効硬化層深さ及び残留オーステナイト量に
ついて調べた結果を示す。[Example] Test steel (Steel: SCM42) whose component composition is shown in Table 1
0, steel: Ni-Mo added steel) were machined according to the gear specifications (spur teeth) shown in Table 2, respectively, and then FIG.
Carburizing was performed under the carburizing and diffusion conditions shown in (d). At this time, a part was subjected to a carbon prevention treatment as shown in FIGS. 2 (a) and 2 (b). The carburizing process shown in FIG. 1 is performed by the gas carburizing process shown in FIG.
Both carburizing treatments were performed under the condition that the surface C content after carburizing was 1.5%. The plasma carburization in FIGS. B to d was performed by using a gear as a cathode and arranging an anode plate around the gear. When a coal-proof jig was used, this was also used as a cathode (auxiliary cathode). The atmosphere was a 3 Torr (H 2 + CH 4 ) atmosphere, of which the partial pressure of CH 4 was 0.8 Torr. Table 3 shows the carburizing conditions. Table 4 shows the results of examination of the surface hardness, carbide area ratio, effective hardened layer depth, and retained austenite amount of the obtained product.
【００１４】[0014]
【表１】 [Table 1]
【００１５】[0015]
【表２】 [Table 2]
【００１６】[0016]
【表３】 [Table 3]
【００１７】[0017]
【表４】 [Table 4]
【００１８】表４より明らかなように、従来のガス浸炭
法（No.1, 2)でも、歯面部については充分な表面硬さが
得られるが、歯元Ｒ部にも炭化物が析出する。この点、
この発明に従うプラズマ浸炭法（No.3〜7)では、炭化物
の析出は歯面部のみであり、歯元Ｒ部はマルテンサイト
＋残留オーステナイト組織となる。この理由は、グロー
放電が歯面部に集中するからである。この傾向は、防炭
治具を用いた場合（No.7）に一層著しい。というのは、
かかる治具の存在により、歯底部ではグローの発生がほ
ぼ完全に防止されるからである。As is clear from Table 4, the conventional gas carburizing method (Nos. 1 and 2) can provide sufficient surface hardness at the tooth surface, but also precipitates carbide at the root portion of the tooth. In this regard,
In the plasma carburizing method (Nos. 3 to 7) according to the present invention, carbide is precipitated only in the tooth surface portion, and the root portion of the tooth has a martensite + retained austenite structure. This is because the glow discharge is concentrated on the tooth surface. This tendency is even more remarkable when a coal-proof jig is used (No. 7). I mean,
This is because the presence of such a jig almost completely prevents the generation of glow at the tooth bottom.
【００１９】次に表５に、得られた製品のピッティング
寿命と切損寿命について調べた結果を示す。Next, Table 5 shows the results obtained by examining the pitting life and the cutting life of the obtained products.
【表５】 [Table 5]
【００２０】同表より明らかなように、この発明に従い
プラズマ浸炭処理を施した歯車（No.3〜7)はいずれも、
従来材に較べてピッティング寿命及び切損寿命とも著し
く改善され、寿命の大幅な延長が達成されている。特に
鋼のNi−Mo鋼は、マトリックスの靭性が元々高いこと
から、寿命のより一層の向上を図ることができた。As is clear from the table, all of the gears (Nos. 3 to 7) subjected to the plasma carburizing treatment according to the present invention have the following characteristics.
The pitting life and the cutting life are remarkably improved as compared with the conventional material, and the life is greatly extended. In particular, the Ni-Mo steel as a steel originally had a high toughness of the matrix, so that the service life could be further improved.
【００２１】[0021]
【発明の効果】かくしてこの発明によれば、短時間で歯
面部のみに深い有効硬化層を形成することができ、従っ
て生産性の向上に併せて、耐ピッティング性及び歯元疲
労強度の向上を実現することができる。As described above, according to the present invention, a deep effective hardened layer can be formed only on the tooth surface in a short period of time, so that the pitting resistance and the root fatigue strength can be improved in addition to the improvement of the productivity. Can be realized.
【図１】浸炭処理条件を示す模式図である。FIG. 1 is a schematic view showing carburizing conditions.
【図２】防炭処理要領を示す模式図である。FIG. 2 is a schematic view showing the procedure of a carbon prevention treatment.
Claims (3)
施すに当たり、プラズマ浸炭法を用い、歯面には炭化物
を析出させる一方、歯元Ｒ部及び歯底部は（マルテンサ
イト＋残留オーステナイト）組織とすることを特徴とす
る歯車の浸炭処理法。When carburizing a gear finished in a predetermined shape, a plasma carburizing method is used to precipitate carbide on the tooth surface, while the root portion and the root portion are (martensite + retained austenite). A method for carburizing gears, characterized by having a texture.
のみを遮蔽する防炭治具の存在下にプラズマ浸炭処理を
施すことを特徴とする歯車の浸炭処理法。2. The method of carburizing gears according to claim 1, wherein plasma carburizing is performed in the presence of a carburizing jig that shields only the root portion and the tooth bottom.
Ni及びMoを複合含有するものである歯車の浸炭処理法。3. The gear material according to claim 1 or 2,
A method for carburizing gears containing a combination of Ni and Mo.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP00511693A JP3182957B2 (en) | 1993-01-14 | 1993-01-14 | Gear carburizing method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP00511693A JP3182957B2 (en) | 1993-01-14 | 1993-01-14 | Gear carburizing method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH06212396A JPH06212396A (en) | 1994-08-02 |
| JP3182957B2 true JP3182957B2 (en) | 2001-07-03 |
Family
ID=11602364
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP00511693A Expired - Fee Related JP3182957B2 (en) | 1993-01-14 | 1993-01-14 | Gear carburizing method |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3182957B2 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3301857B2 (en) * | 1994-03-29 | 2002-07-15 | マツダ株式会社 | Carburizing method |
| JP2017180675A (en) * | 2016-03-30 | 2017-10-05 | Ntn株式会社 | Tripod type constant velocity universal joint and heat treatment method for tripod member |
-
1993
- 1993-01-14 JP JP00511693A patent/JP3182957B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH06212396A (en) | 1994-08-02 |
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