JPH0360898B1

JPH0360898B1 -

Info

Publication number: JPH0360898B1
Application number: JP5301682A
Authority: JP
Inventors: Ryoji Tanaka
Original assignee: Daido Steel Co Ltd
Current assignee: Daido Steel Co Ltd
Priority date: 1982-03-31
Filing date: 1982-03-31
Publication date: 1991-09-18
Also published as: JPS58171554A; JPS62096647A; JPH0558055B2

Description

[Detailed description of the invention]

発明の目的 purpose of invention

[Industrial application field]

本発明は、疲れ強さを高めた歯車の製造方法に
関する。 The present invention relates to a method for manufacturing a gear with increased fatigue strength.

[Conventional technology]

一般に、機械構造用部品は高い疲れ強さを要求
されるので、材料の選択に配慮するだけでなく、
とくに表面に強い応力が加わるような用途に向け
るものにあつては、表面硬化処理を行なうことが
多い。このような目的で実施する表面硬化処理法
の代表的なものは、浸炭焼入れおよび高周波焼入
れである。よく知られているように、浸炭焼入れは高度の
表面硬化ができるが、長時間の加熱を要し、多く
のエネルギーを消費することと、処理に伴う変形
が大きいという難点がある。一方、高周波焼入れ
は、短時間の処理で実施できて省エネルギーの観
点から好ましい上に、変形が小さいため仕上げ加
工が不溶または簡単ですむといつた利点はある
が、表面硬化の度合は浸炭焼入れに及ばない。そのため、高い表面強度を必要とする用途、た
とえば自動車用変速機歯車のような機械構造用部
品については、高周波焼入れはほとんど行なわれ
ていない。本発明者は、上記した高周波焼入れの利点を生
かし、その焼入れ効果をより高く得ることによつ
て、適用可能な場合を多くすることを企てて研究
を重ねた。その結果、従来の炭素鋼よりもSiの含
有量を高めた鋼においてこの意図が実現すること
を見出した。 In general, mechanical structural parts are required to have high fatigue strength, so in addition to considering the selection of materials,
In particular, for applications where strong stress is applied to the surface, surface hardening treatment is often performed. Typical surface hardening treatment methods carried out for this purpose are carburizing and hardening and induction hardening. As is well known, carburizing and quenching can achieve a high degree of surface hardening, but it requires long heating times, consumes a lot of energy, and has the disadvantages of large deformation due to the treatment. On the other hand, induction hardening has the advantage that it can be carried out in a short time and is preferable from the viewpoint of energy saving, and that the finishing process is easy or insoluble due to small deformation, but the degree of surface hardening is not as good as that of carburizing hardening. do not have. For this reason, induction hardening is rarely performed for applications that require high surface strength, for example mechanical structural parts such as automobile transmission gears. The inventor of the present invention has conducted repeated research in an attempt to increase the number of cases in which induction hardening can be applied by taking advantage of the above-mentioned advantages of induction hardening and obtaining a higher hardening effect. As a result, they found that this intention was realized in steel with a higher Si content than conventional carbon steel.

[Problems to be solved by the invention]

本発明の目的は、上記したSi含有量の高い鋼を
使用して高周波焼入れの利点をフルに生かし、疲
れ強さの高い歯車を製造する方法を提供すること
にある。発明の構成 An object of the present invention is to provide a method for manufacturing gears with high fatigue strength by fully utilizing the advantages of induction hardening using the above-mentioned steel with a high Si content. Composition of the invention

[Means to solve the problem]

本発明の、疲れ強さの高い歯車の製造方法は、
Ｃ：0.30〜0.60％、Si：0.40％超過〜0.80％未満お
よびMn：0.40〜2.0％を含有し残部がFeおよび不
可避の不純物からなる鋼を材料とし、式 logf＝Ａ／ｍ［式中、ｆは周波数（ＫHz）、ｍは歯車のモジユ
ールをあらわし、Ａは比例定数である。］におい
てＡが３〜10の範囲となる周波数の高周波を用い
て焼入れを施すことを特徴とする。 The method of manufacturing a gear with high fatigue strength of the present invention includes:
The material is steel containing C: 0.30 to 0.60%, Si: more than 0.40% to less than 0.80%, and Mn: 0.40 to 2.0%, with the balance consisting of Fe and unavoidable impurities, and the formula logf = A / m [in the formula, f is the frequency (KHz), m is the gear module, and A is the proportionality constant. ] is characterized in that hardening is performed using high frequency waves with a frequency in which A is in the range of 3 to 10.

[Effect]

上記の合金組成を定めた理由は、つぎのとおり
である。Ｃ含有量0.30〜0.60％は機械構造用の炭素鋼の
通常採用されている範囲であり、下限は高周波焼
入れにより所定の表面硬さを得るために最低限必
要な量であり、また上限はこれを超えると焼ワレ
の危険があることから設けた。 Si含有量0.40％超過〜0.80％未満は、炭素鋼に
一般的な0.15〜0.35％の範囲を外れた高い値であ
る。下限は高周波焼入れにより高い表面硬化を得
る上で必要であり、上限は被削性が良好に保たれ
る範囲という観点から定めた。 Mnの含有量0.40〜2.0％は、炭素鋼に代表的な
範囲を包含して、比較的広い範囲に及んでいる。
下限値は脱酸および焼入性の確保のために必要で
あり、上限は、Siとともに被削性にかんがみて決
定した。歯車の疲れ強さは、歯元における曲げ疲れ強さ
と、歯面における面疲れ強さとが問題であつて、
前者は歯の折損の可能性を左右し、後者は摩耗に
よる寿命を決定する。曲げ疲れ強さを高めるため
には、歯元の隅肉部の表面硬化後の残留応力が、
引張りでなく圧縮であることが望ましい。上記
の、比例定数Ａ＝３〜10の範囲は、こうした望ま
しい表面硬化を起させる条件である。また、従来
にない高いSi含有量は、高周波焼入れ後の歯面の
疲れ強さを向上させる。実施例第１表に示す化学組成の鋼を溶製した。比較の
ためあげたS35C、S45CおよびS55Cは、従来から
高周波焼入れを適用して機械構造用部品を製造す
るのに用いられている炭素鋼であり、SCM420
は、浸炭焼入れを行なう鋼である。 The reason for determining the above alloy composition is as follows. C content of 0.30 to 0.60% is the range normally adopted for carbon steel for machine structures, the lower limit is the minimum amount necessary to obtain a specified surface hardness by induction hardening, and the upper limit is this. This was established because there is a risk of burn damage if the temperature is exceeded. The Si content of more than 0.40% to less than 0.80% is a high value outside the range of 0.15 to 0.35% that is common for carbon steel. The lower limit is necessary to obtain high surface hardening by induction hardening, and the upper limit is determined from the viewpoint of maintaining good machinability. The Mn content ranges from 0.40 to 2.0% over a relatively wide range, including the range typical of carbon steel.
The lower limit is necessary to ensure deoxidation and hardenability, and the upper limit was determined in consideration of machinability as well as Si. The fatigue strength of gears is a matter of bending fatigue strength at the tooth root and surface fatigue strength at the tooth surface.
The former determines the possibility of tooth breakage, and the latter determines the lifespan due to wear. In order to increase bending fatigue strength, the residual stress after surface hardening in the fillet of the tooth base must be
It is desirable to use compression rather than tension. The above-mentioned range of proportionality constant A=3 to 10 is a condition for causing such desirable surface hardening. Furthermore, the unprecedentedly high Si content improves the fatigue strength of the tooth surface after induction hardening. Example Steel having the chemical composition shown in Table 1 was melted. S35C, S45C and S55C mentioned for comparison are carbon steels traditionally used to manufacture mechanical structural parts by applying induction hardening, and SCM420
is a steel that undergoes carburizing and quenching.

【表】各鋼から、第２表に示すような歯車形試験片
を、切削により製造した。第２表試験片諸元大歯車小歯車種類平歯車平歯車モジユール各種各種歯数各種各種圧力角 20゜ 20゜ピツチ円形 80mm 70mm 歯先円形 85mm 75mm 歯幅 10mm ８mm 荒仕上げホブホブ精仕上歯研歯研ついで、各試験片を、第３表に示す条件で高周
波焼入れし、表面を硬化させた。なお、SCM420
は浸炭焼入れした。第３表高周波焼入れ条件大歯車小歯車方式定置焼入れコイル 95φ×15 85φ×15 周波数各種加熱時間 5sec 移動速度 − 陽極電圧 8KV 陽極電流 5.5A 格子電流 1.5A 待ち時間 2sec 冷却水溶性焼入剤噴射焼もどし 160℃×90minW.C. これらの試験片について、第４表に示す条件の
耐久試験を行なうとともに、供試鋼Ａでつくつた
ものの、歯元隅肉部の残留応力を測定した。耐久
誌験の結果は図面のグラフに示し、残留応力は第
５表に掲げる。第４表試験条件歯車方式定置焼入れ応力ヘルツ応力〜250Kgｆ／mm² 潤滑油出光ギヤオイル HE−90S（40℃）寿命判定歯折損または歯面損傷回転数 5160rpm[Table] Gear-shaped test pieces as shown in Table 2 were manufactured from each steel by cutting. Table 2 Test piece specifications Large gear Small gear Type Spur gear Spur gear Module Various Various Number of teeth Various Various Pressure Angle 20° 20° Pitch circular 80mm 70mm Tip circular 85mm 75mm Teeth width 10mm 8mm Rough finishing Hob Hob Fine finishing Top Tooth Grinding Tooth Grinding Next, each test piece was induction hardened under the conditions shown in Table 3 to harden the surface. In addition, SCM420
was carburized and quenched. Table 3 Induction hardening conditions Large gear small gear system Hardening in place Coil 95φ×15 85φ×15 Frequency Various Heating time 5sec Traveling speed - Anode voltage 8KV Anode current 5.5A Grid current 1.5A Waiting time 2sec Cooling Water-soluble quenching agent Injection Tempering 160°C x 90 minW.C. These test pieces were subjected to durability tests under the conditions shown in Table 4, and the residual stress in the fillets at the root of the teeth was measured for those made from sample steel A. The results of the durability test are shown in the graph of the drawing, and the residual stress is listed in Table 5. Table 4 Test conditions Gear system Hardening in place stress Hertzian stress ~ 250Kgf/mm ² Lubricating oil Idemitsu gear oil HE-90S (40℃) Life judgment Tooth breakage or tooth surface damage Rotation speed 5160rpm

【表】の条件をみたす。
図面からも、本発明に従つて製造した歯車がす
ぐれた疲れ強さを有することがわかる。また第５
表のデータは、本発明によれば歯元隅肉部の残留
応力が、常に圧縮側に得られることを裏付けてい
る。発明の効果本発明により、高周波焼入れを、高い疲れ強さ
を要求される歯車の製造に採用することが可能に
なり、その長所をフルに利用して、すぐれた特性
をもつ歯車が得られるようになつた。The conditions in [Table] are met.
It can also be seen from the drawings that the gear manufactured according to the invention has excellent fatigue strength. Also the fifth
The data in the table confirm that according to the present invention, the residual stress in the root fillet is always obtained on the compression side. Effects of the Invention The present invention makes it possible to apply induction hardening to the manufacture of gears that require high fatigue strength, and to fully utilize its advantages to obtain gears with excellent characteristics. It became.

[Brief explanation of drawings]

図面は、本発明の方法により製造した歯車の疲
れ強さを、従来の製品と比較して示すグラフであ
る。 The drawing is a graph showing the fatigue strength of gears manufactured by the method of the present invention in comparison with conventional products.

Claims

[Claims] 1. C: 0.30 to 0.60%, Si: exceeding 0.40% by weight
The material is steel containing less than 0.80% and Mn: 0.4 to 2.0%, with the balance consisting of Fe and unavoidable impurities, and the formula logf = A/m [where f is the frequency (KHz) and m is the gear module]. , where A is a proportionality constant. ] A method for manufacturing a gear with high fatigue strength, characterized in that hardening is performed using high frequency at a frequency where A is in the range of 3 to 10.