JPH02160428A - Manufacture of high strength gear - Google Patents
Manufacture of high strength gearInfo
- Publication number
- JPH02160428A JPH02160428A JP31066388A JP31066388A JPH02160428A JP H02160428 A JPH02160428 A JP H02160428A JP 31066388 A JP31066388 A JP 31066388A JP 31066388 A JP31066388 A JP 31066388A JP H02160428 A JPH02160428 A JP H02160428A
- Authority
- JP
- Japan
- Prior art keywords
- gear
- grain boundary
- layer
- hardening layer
- fatigue 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.)
- Pending
Links
- 238000004519 manufacturing process Methods 0.000 title claims description 12
- 238000005498 polishing Methods 0.000 claims abstract description 24
- 238000005480 shot peening Methods 0.000 claims abstract description 16
- 238000004381 surface treatment Methods 0.000 claims abstract description 6
- 239000010410 layer Substances 0.000 claims description 31
- 238000000034 method Methods 0.000 claims description 26
- 238000005255 carburizing Methods 0.000 claims description 18
- 239000002344 surface layer Substances 0.000 claims description 9
- 239000000463 material Substances 0.000 abstract description 3
- 238000010791 quenching Methods 0.000 abstract description 3
- 230000000171 quenching effect Effects 0.000 abstract description 3
- 238000005482 strain hardening Methods 0.000 abstract description 3
- 230000001590 oxidative effect Effects 0.000 abstract 4
- 230000003647 oxidation Effects 0.000 description 19
- 238000007254 oxidation reaction Methods 0.000 description 19
- 230000007423 decrease Effects 0.000 description 7
- 230000003746 surface roughness Effects 0.000 description 7
- 238000010586 diagram Methods 0.000 description 5
- 238000005256 carbonitriding Methods 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 238000009499 grossing Methods 0.000 description 2
- 238000011282 treatment Methods 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 101100202505 Saccharomyces cerevisiae (strain ATCC 204508 / S288c) SCM4 gene Proteins 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 235000010724 Wisteria floribunda Nutrition 0.000 description 1
- 238000010420 art technique Methods 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000003754 machining Methods 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 238000003672 processing method Methods 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
Landscapes
- Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)
- Gears, Cams (AREA)
Abstract
Description
【発明の詳細な説明】
〔産業上の利用分野〕
本発明は、歯車の製造方法に係り、さらに詳しくは、成
形加工した歯車表面に形成される圧縮残留応力が低い粒
界酸化層を電解研摩して疲労強度を向上できるようにし
た高強度歯車の製造方法に関する。DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing gears, and more specifically, the present invention relates to a method for manufacturing gears, and more specifically, a grain boundary oxidation layer with low compressive residual stress formed on the surface of a formed gear is removed by electrolytic polishing. The present invention relates to a method for manufacturing high-strength gears that can improve fatigue strength.
一般に、成形加工された歯車に耐摩耗性および強じん性
などの強度を持たせるために、浸炭法。Generally, carburizing is used to give formed gears strength such as wear resistance and toughness.
浸炭窒化法等の特殊な熱処理を施して歯車表面に硬化層
を形成する方法、および浸炭法または浸炭窒化法とショ
ットピーニング法とを組み合わせて表面を硬化させる方
法等が知られている。There are known methods in which a hardened layer is formed on the gear surface by applying a special heat treatment such as carbonitriding, and a method in which the surface is hardened by combining carburizing or carbonitriding and shot peening.
ここで、上記浸炭法は最も多く使用されている方法で、
歯車などのように、表面硬化層の部分と強じん性のある
中心に近い部分とを要する部品に最適であり、しかも浸
炭法の一種である浸炭窒化法は炭素と同時に窒素も多量
に浸入させた表面硬化法である。Here, the above carburizing method is the most commonly used method,
It is ideal for parts such as gears that require a hardened surface layer and a tough central part, and the carbonitriding method, which is a type of carburizing method, allows a large amount of nitrogen to enter at the same time as carbon. This is a surface hardening method.
また、歯車表面層に形成される圧縮残留応力と加工硬化
によって部材の疲れ強度を向上させる表面加工処理法の
一つであるショットピーニング法には、例えば特公昭６
２−７２４５号公報に示すような先行技術が知られてい
る。In addition, shot peening, which is one of the surface processing methods that improves the fatigue strength of parts by compressive residual stress and work hardening formed on the gear surface layer, includes, for example,
A prior art technique as shown in Japanese Patent No. 2-7245 is known.
ところが、上述した浸炭法により歯車表面に浸炭焼入れ
を行なった場合は、例えば第２図に示すようにＳＣＭ４
２０等の強じん鋼では、歯車表面に深さｄｎ（数μｍか
ら数ＩＯμｆｆ１）なる粒界酸化層ｍ（５Ｉ 、Ｍｎ
、Ｃｒ等の酸化物）が形成されると共に、第３図に示す
ように上記歯車表面近傍の疲労強度τ（ｋｇｆ’／■’
）は粒界酸化層ｍの深さｄｎが深くなるにしたがい低
下し、表面圧縮残留応力が減少すぎため、強度低下の一
因となっている。However, when the gear surface is carburized and quenched by the above-mentioned carburizing method, the SCM4
In strong steel such as No. 20, the gear surface has a grain boundary oxidation layer m (5I, Mn
, oxides such as Cr) are formed, and as shown in FIG. 3, the fatigue strength τ (kgf'/■'
) decreases as the depth dn of the grain boundary oxidation layer m increases, and the surface compressive residual stress decreases too much, which is one of the reasons for the decrease in strength.
また、上述したショットピーニング法による先行技術で
は、第４図に示すように歯車表面層に浸炭焼入れを施し
た後、ショットピーニング法により表面硬化処理を施し
た場合の圧縮残留応力σ（ｋｇ／ｍｌ１１）は、深さｄ
ｌで最大値ａ ｍａｘをとり、それより表面側では急激
に小さくなり、またｄｌから深くなるにつれて徐々に小
さくなる。In addition, in the prior art using the shot peening method described above, as shown in FIG. 4, the compressive residual stress σ (kg/ml11 ) is the depth d
It takes a maximum value a max at l, rapidly decreases on the surface side, and gradually decreases as it goes deeper from dl.
さらに、上記ショットピーニング法による表面粗さγ（
μＩＫ）と歯車の疲労寿命Ｎとの関係は第５図に示すよ
うになっており、平滑な表面はど疲労寿命Ｎが延長する
ことが知られている。したがってショットピーニング法
だけで表面粗さの加工精度をコントロールするのが困難
であり、しかも歯先面、歯面および歯底面によって各部
位の強度に合わせた表面粗さを制御する装置が必要とな
り、コスト高になるなどの問題がある。Furthermore, the surface roughness γ (
The relationship between μIK) and the fatigue life N of a gear is shown in FIG. 5, and it is known that the fatigue life N of a gear is longer when the surface is smooth. Therefore, it is difficult to control the machining accuracy of the surface roughness using only the shot peening method, and moreover, a device is required to control the surface roughness according to the strength of each part depending on the tooth top surface, tooth surface, and tooth bottom surface. There are problems such as high costs.
本発明は、上述の問題点を課題として提案されたもので
、従来のような浸炭法などの表面処理とショットピーニ
ング法とにより形成された粒界酸化層における圧縮応力
の低い部分を電解研摩法によって研摩するなどの手段に
より、歯車の疲労強度゛を一段と向上させてなる高強度
歯車の製造方法を提供することを目的とするものである
。The present invention was proposed to address the above-mentioned problems, and uses electrolytic polishing to remove areas with low compressive stress in the grain boundary oxidation layer formed by conventional surface treatments such as carburizing and shot peening. It is an object of the present invention to provide a method for manufacturing a high-strength gear in which the fatigue strength of the gear is further improved by means such as polishing.
この目的を達成するため、本発明によれば、成形加工さ
れた歯車の表面処理において、上記歯車表面に浸炭、ま
たは浸炭後にショットピーニングを行なうことにより表
面硬化層を形成し、上記表面硬化層の圧縮残留応力の低
い粒界酸化層を電解研摩によって研摩したことを特徴と
するものである。In order to achieve this object, according to the present invention, in surface treatment of a formed gear, a surface hardening layer is formed by carburizing the surface of the gear, or by performing shot peening after carburizing. It is characterized by having a grain boundary oxidation layer with low compressive residual stress polished by electrolytic polishing.
このように、本発明による高強度歯車の製造方法では、
成形加工された歯車表面に浸炭、または浸炭後にショッ
トピーニングを行なった後、その表面を電解研摩によっ
て研摩して平滑化したので、歯車表面直下の粒界酸化層
（数μｍから数１０μＩＩりより内部の高圧縮残留応力
を有する表面硬化層を、表面に露出させることができる
。As described above, in the method for manufacturing a high-strength gear according to the present invention,
After carburizing the formed gear surface or shot peening after carburizing, the surface was polished and smoothed by electrolytic polishing. A hardened surface layer having a high compressive residual stress of 100 mL can be exposed on the surface.
したがって、上記電解研摩法により、粒界酸化層を研摩
することによって疲労強度の向上を図ることができると
共に、この研摩代を調整することによって、適切な疲労
強度に設定することが可能になる。Therefore, by the electrolytic polishing method described above, fatigue strength can be improved by polishing the grain boundary oxidation layer, and by adjusting this polishing allowance, it is possible to set an appropriate fatigue strength.
以下、本発明による実施例を添付の図面に基づいて詳細
に説明する。Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.
まず、第１図において、所定の材料（ＳＣＭ４２０など
）により成形加工された歯車ｌの表面に、耐摩耗性や疲
労強度を持たせるために、浸炭焼入れを施して表面硬化
層２が形成される。この表面硬化層２の外表には粒界酸
化層が形成される。First, in FIG. 1, a hardened surface layer 2 is formed on the surface of a gear l formed from a predetermined material (such as SCM420) by carburizing and quenching in order to provide wear resistance and fatigue strength. . A grain boundary oxidation layer is formed on the outer surface of this hardened surface layer 2.
上記表面硬化層２の外表には、第２図から明らかなよう
に粒界酸化層ｍが歯車１の表面からｄｎの高さにわたっ
て形成されており、疲労強度τは粒界酸化層ｍの深さｄ
ｎが深くなるにしたがって減少する。As is clear from FIG. 2, a grain boundary oxidation layer m is formed on the outer surface of the surface hardening layer 2 over a height of dn from the surface of the gear 1, and the fatigue strength τ is determined by the depth of the grain boundary oxidation layer m. Sad
It decreases as n becomes deeper.
次に、上記粒界酸化層ｍを含む表面硬化層２にショット
ピーニング法による表面処理が施されて、表面硬化層２
に発生する圧縮残留応力と加工硬化によって部材の疲労
強度を上昇させる。Next, the surface hardened layer 2 including the grain boundary oxidation layer m is subjected to surface treatment by shot peening, and the surface hardened layer 2 is
The fatigue strength of the member is increased by the compressive residual stress and work hardening generated in the process.
すなわち、上記浸炭法により歯車１の表面層に熱処理を
施した後、ショットピーニング法による表面処理を施し
た場合の圧縮残留応力σ（ｋｇｆ’／ａｍ’ ）は、第
４図に示すようになっており、この圧縮残留応力σは深
さｄｌの位置で最大となる。That is, the compressive residual stress σ (kgf'/am') when the surface layer of the gear 1 is heat treated by the carburizing method and then surface treated by the shot peening method is as shown in FIG. This compressive residual stress σ is maximum at the depth dl.
したがって、上記表面硬化層２の深さｄｌを研摩するこ
とによって粒界酸化層ｍを取り除き、高圧縮残留応力を
有する表面硬化層２が表面に露出することになり、疲労
強度を向上させることができる。Therefore, by polishing the depth dl of the surface hardening layer 2, the grain boundary oxidation layer m is removed, and the surface hardening layer 2 having high compressive residual stress is exposed on the surface, thereby improving fatigue strength. can.
このために、本発明では、上記粒界酸化層ｍ等を安定で
、且つ均一に研摩するために電気エネルギで金属の溶解
を行なう電解研摩法が適用される。For this reason, in the present invention, in order to stably and uniformly polish the grain boundary oxide layer m, etc., an electrolytic polishing method is applied in which metal is melted with electrical energy.
上記電解研摩法では、歯車１の材料に応じて溶液組成、
温度、電流密度または電圧を適正値に制御することによ
って研摩代を調整することができるものであるから、上
記粒界酸化層ｍ等の研摩代を調整して適切な疲労強度に
設定することが可能になる。In the above electrolytic polishing method, the solution composition varies depending on the material of the gear 1.
Since the polishing allowance can be adjusted by controlling the temperature, current density, or voltage to appropriate values, it is possible to adjust the polishing allowance of the grain boundary oxide layer m, etc. to set an appropriate fatigue strength. It becomes possible.
一方、上記歯車１の疲労寿命Ｎおよびピッチング寿命Ｎ
′と、表面処理されたｍ面の粗さγ（μｍ）との関係は
第５図に示すようになっており、歯面の粗さγが細かく
なるにしたがって、疲労寿命Ｎおよびピッチング寿命Ｎ
′が延長されるものである。On the other hand, the fatigue life N and pitting life N of the gear 1
' and the roughness γ (μm) of the surface-treated m-surface is shown in Figure 5. As the tooth surface roughness γ becomes finer, the fatigue life N and pitting life N decrease.
′ is extended.
このようにして、本発明による歯車の製造方法では、成
形加工された歯車表面に浸炭、または浸炭とショットピ
ーニングとを組合せた表面硬化処理を施した後、これに
よって形成される粒界酸化層を電解研摩によって除去し
平滑化したので、疲労クラックの起点となる粒界酸化層
がなくなり、歯車の疲労強度およびピッチング強度が向
上する。In this way, in the gear manufacturing method according to the present invention, after carburizing the formed gear surface or surface hardening treatment using a combination of carburizing and shot peening, the grain boundary oxidation layer formed thereby is removed. Since it is removed and smoothed by electrolytic polishing, the grain boundary oxidation layer that becomes the starting point of fatigue cracks is eliminated, and the fatigue strength and pitting strength of the gear are improved.
また、上記電解研摩による研摩代を調整することによっ
て、適切な強度に設定することができる。Moreover, by adjusting the polishing allowance by the electrolytic polishing described above, it is possible to set the strength to an appropriate level.
なお、本発明による実施例では、歯車表面に浸炭焼入れ
を施して浸炭硬化層を形成し、さらにショットピーニン
グによって表面硬化処理した後に電解研摩法によって粒
界酸化層を研摩する方法について説明したが、これに限
定するものではなく、浸炭によって形成された粒界酸化
層を電解研摩で研摩し、その後にショットピーニングを
施して歯車の歯底などを所定の表面粗さに加工すること
も可能である。゛
〔発明の効果〕
以上説明したように、本発明によれば、歯車の製造方法
において、浸炭焼入れによって表面硬化層の外表に形成
された圧縮残留応力の低い粒界酸化層を電解研摩によっ
て研摩することにより平滑化したので、歯車の疲労強度
を向上させるとともに、表面粗さが細かくなるよう平滑
化したので歯車寿命の延長を図ることができる。In addition, in the embodiment according to the present invention, a method was described in which the gear surface is carburized and quenched to form a carburized hardened layer, and then the grain boundary oxidation layer is polished by electrolytic polishing after surface hardening treatment by shot peening. The method is not limited to this, but it is also possible to polish the grain boundary oxidation layer formed by carburization using electrolytic polishing, and then perform shot peening to process the bottom of the tooth of a gear to a predetermined surface roughness. . [Effects of the Invention] As explained above, according to the present invention, in the gear manufacturing method, the grain boundary oxidation layer with low compressive residual stress formed on the outer surface of the hardened surface layer by carburizing and quenching is polished by electrolytic polishing. By smoothing the surface, the fatigue strength of the gear can be improved, and by smoothing the surface so that the surface roughness is fine, it is possible to extend the life of the gear.
また、電解研摩による研摩代を調整することにより、適
切な強度を有する歯車の製造が可能である。Further, by adjusting the polishing allowance by electrolytic polishing, it is possible to manufacture a gear having appropriate strength.
第１図は本発明による歯車製造方法の工程図、第２図は
浸炭による粒界酸化層を示す図、第３図は疲労強度と粒
界酸化層の深さとの特性図、第４図は浸炭とショットピ
ーニングとによる残留応力の特性図、第５図は歯面粗さ
と寿命との特゛性図である。
■・・・歯車、２・・・表面硬化層、ｍ・・・粒界酸化
層。
第１図
第２図
特許出願人 富士重工業株式会社第３図Figure 1 is a process diagram of the gear manufacturing method according to the present invention, Figure 2 is a diagram showing grain boundary oxidation layers due to carburization, Figure 3 is a characteristic diagram of fatigue strength and depth of grain boundary oxidation layers, and Figure 4 is A characteristic diagram of residual stress due to carburizing and shot peening, and FIG. 5 is a characteristic diagram of tooth surface roughness and life. ■...Gear, 2...Surface hardening layer, m...Grain boundary oxidation layer. Figure 1 Figure 2 Patent applicant Fuji Heavy Industries Ltd. Figure 3
Claims (1)
グを行なうことにより表面硬化層を形成し、 上記表面硬化層の圧縮残留応力の低い粒界酸化層を電解
研摩によって研摩したことを特徴とする高強度歯車の製
造方法。[Claims] In the surface treatment of a molded gear, a hardened surface layer is formed by carburizing the surface of the gear, or shot peening is performed after carburizing, and the grain boundaries of the hardened surface layer have low compressive residual stress. A method for manufacturing a high-strength gear, characterized in that the oxide layer is polished by electrolytic polishing.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP31066388A JPH02160428A (en) | 1988-12-08 | 1988-12-08 | Manufacture of high strength gear |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP31066388A JPH02160428A (en) | 1988-12-08 | 1988-12-08 | Manufacture of high strength gear |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH02160428A true JPH02160428A (en) | 1990-06-20 |
Family
ID=18007959
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP31066388A Pending JPH02160428A (en) | 1988-12-08 | 1988-12-08 | Manufacture of high strength gear |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH02160428A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH04331270A (en) * | 1991-05-02 | 1992-11-19 | Chisso Corp | Printing ink composition |
| JP2008297618A (en) * | 2007-06-02 | 2008-12-11 | Sanyo Special Steel Co Ltd | Method for manufacturing carburized steel part excellent in indentation resistance |
-
1988
- 1988-12-08 JP JP31066388A patent/JPH02160428A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH04331270A (en) * | 1991-05-02 | 1992-11-19 | Chisso Corp | Printing ink composition |
| JP2008297618A (en) * | 2007-06-02 | 2008-12-11 | Sanyo Special Steel Co Ltd | Method for manufacturing carburized steel part excellent in indentation resistance |
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