JP2716141B2 - Spring material - Google Patents
Spring materialInfo
- Publication number
- JP2716141B2 JP2716141B2 JP63116365A JP11636588A JP2716141B2 JP 2716141 B2 JP2716141 B2 JP 2716141B2 JP 63116365 A JP63116365 A JP 63116365A JP 11636588 A JP11636588 A JP 11636588A JP 2716141 B2 JP2716141 B2 JP 2716141B2
- Authority
- JP
- Japan
- Prior art keywords
- hardness
- spring
- peak
- distribution
- stress
- 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
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
- F16F1/00—Springs
- F16F1/02—Springs made of steel or other material having low internal friction; Wound, torsion, leaf, cup, ring or the like springs, the material of the spring not being relevant
Landscapes
- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Springs (AREA)
Description
【発明の詳細な説明】 ［産業上の利用分野］ 本発明は、例えば自動車の弁ばねや懸架用ばね等に好
適な高耐久性を有するばね用材料に関する。Description: TECHNICAL FIELD The present invention relates to a highly durable spring material suitable for, for example, a valve spring or a suspension spring of an automobile.
［従来の技術］ 一般的な熱処理によって調質されたばね用材料の断面
内硬さ分布は第８図に模式的に示されるように表面から
中心部にわたって硬さがほぼ均等である。[Prior Art] The hardness distribution in a cross section of a spring material tempered by a general heat treatment is substantially uniform in hardness from the surface to the center as schematically shown in FIG.
これに対し浸炭あるいは窒化処理が行なわれた材料
は、第９図に示されるように表面部の硬さが高くなって
いる。浸炭あるいは窒化によって表面を強化した材料
は、硬化深さが浅い割には硬さのピーク値ａと中心部の
硬さｂとの差（ａ−ｂ）が大きい。硬度差（ａ−ｂ）が
ビッカース硬さ（HMV）で150を越えるようになると、硬
さが変化する箇所ｃ付近に応力集中を生じやすくなり耐
疲れ性はかえって低下する。On the other hand, the material subjected to the carburizing or nitriding treatment has a high surface hardness as shown in FIG. For a material whose surface has been strengthened by carburizing or nitriding, the difference (ab) between the peak value a of hardness and the hardness b at the central portion is large, although the hardening depth is shallow. When the hardness difference (ab) exceeds 150 in Vickers hardness (HMV), stress concentration tends to occur near the portion c where the hardness changes, and fatigue resistance is rather reduced.
一方、特開昭62−74027号公報や特開昭62−260015号
公報あるいは特開昭62−260020号公報などに示されてい
るばね材料は、第10図のように表面硬さｄを中心部硬さ
ｂよりも低下させることによって切欠き感受性を緩和
し、耐疲れ性を向上させている。この場合、具体的には
母材を熱処理によってある所定硬さに調質後、高周波誘
導加熱手段等の急速加熱手段により、表面から所定の深
さだけ軟化させている。On the other hand, the spring materials disclosed in JP-A-62-74027, JP-A-62-260015 or JP-A-62-260020 have a center on the surface hardness d as shown in FIG. Notch sensitivity is reduced by lowering the hardness than the part hardness b, and fatigue resistance is improved. In this case, specifically, after the base material is tempered to a predetermined hardness by heat treatment, the base material is softened to a predetermined depth from the surface by a rapid heating means such as a high-frequency induction heating means.
［発明が解決しようとする課題］ 硬さに関して言えば、耐疲れ性に最も影響を与えるの
は材料の表面からやや内側に入った部分である。ところ
が前記先行技術によって表面部を軟化させた材料は、表
面部を除くほぼ断面全域が同じ硬さと延性をもつから、
所望の耐疲れ性を発揮させるために一定レベル以上の硬
さにすると、コイルばね等に成形する際に大きな力が必
要であるなど加工しにくく、かつ成形後のスプリングバ
ック量も大きいといった問題がある。[Problems to be Solved by the Invention] In terms of hardness, the part that has the most influence on fatigue resistance is a part slightly inside the surface of the material. However, since the material whose surface is softened by the prior art has almost the same cross-sectional area except the surface, the same hardness and ductility,
If the hardness is more than a certain level in order to exhibit the desired fatigue resistance, there is a problem that it is difficult to process such as requiring a large force when forming into a coil spring and the like, and the amount of springback after forming is large. is there.
従って本発明の目的は、切欠き感受性を緩和できるだ
けでなく優れた耐疲れ性を有しかつ加工性もよいばね用
材料を提供することにある。SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a spring material which not only can reduce notch sensitivity but also has excellent fatigue resistance and good workability.
［課題を解決するための手段］ 上記目的を果たすために本発明のばね用材料は、表面
からやや内側に入った表層部に硬さのピークを生じさ
せ、しかも表面の硬さが上記ピーク値よりも小さく、か
つ表層部よりも中心側の部分の硬さも上記ピーク値より
も小さい硬さ分布となるように調質し、かつ、硬さのピ
ーク位置e1が、ショットピーニングによって付与される
圧縮残留応力のピーク位置c1からばね使用時に最大応力
を生じる位置c2の間に入る硬さ分布となるように調質し
たものである。[Means for Solving the Problems] In order to achieve the above object, the spring material of the present invention causes a hardness peak to occur in a surface layer slightly inward from the surface, and the surface hardness has the peak value. Smaller, and the hardness of the portion on the center side of the surface layer is also tempered so as to have a hardness distribution smaller than the peak value, and the peak position e 1 of the hardness is given by shot peening. is obtained by tempering so that the hardness distribution falling between the positions c 2 resulting in maximum stress at peak positions c 1 to the spring used in the compressive residual stress.
［作用］ 本発明のばね用材料においては、表面硬さを下げるこ
とによって切欠き感受性が緩和されるとともに、耐疲れ
性の向上に最も効果のある表面からやや内側に入ったと
ころの表層部に硬さのピークがある。そしてこのピーク
位置よりも中心側の部分の硬さが下がっているから、表
面部のみが軟化している材料に比べると絞りで５〜20％
ほど延性を大きくすることができ、同じ耐疲れ性であれ
ば延性が小さい分だけコイルばね等への成形が容易であ
る。ショットピーニングを行うばねでは、材料表面から
ある程度の深さにわたって圧縮残留応力が生じる。ばね
の耐疲れ性はこの圧縮残留応力の分布状態とその領域で
の硬さに左右される。また、耐疲れ性は、材料表面から
やや内側に入った箇所の硬さにも左右される。しかして
本発明のように、硬さのピーク位置e1が、ショットピー
ニングによって付与される圧縮残留応力のピーク位置c1
からばね使用時に最大応力を生じる位置c2の間に入るよ
うな硬さ分布となるように調質しておけば、ばねの耐疲
れ性が著しく高まる。[Action] In the spring material of the present invention, notch sensitivity is reduced by lowering the surface hardness, and the surface layer portion slightly inside from the surface that is most effective in improving fatigue resistance is applied to the surface layer. There is a peak in hardness. And since the hardness of the part on the center side lower than this peak position is reduced by 5 to 20% compared with the material whose surface part is only softened.
The greater the ductility, the easier it is to form into a coil spring or the like due to the smaller ductility if the fatigue resistance is the same. In a spring that performs shot peening, compressive residual stress is generated over a certain depth from the material surface. The fatigue resistance of the spring depends on the distribution state of the compressive residual stress and the hardness in that region. In addition, the fatigue resistance also depends on the hardness of a portion slightly inside the material surface. Thus, as in the present invention, the peak position e 1 of the hardness is the peak position c 1 of the compressive residual stress applied by shot peening.
Once it has tempering so that the hardness distribution as fall between the positions c 2 resulting in maximum stress when to the spring used, resistance to fatigue of the spring is increased considerably.
なお、圧縮残留応力のピーク位置c1や、ばね使用時に
最大応力を生じる位置c2などは、Ｘ線を利用した応力測
定装置を用いて材料内部の金属結晶の歪み等を解析する
ことによって知ることができる。硬さのピーク位置e1に
ついては、径方向に切断された材料の断面を、マイクロ
ビッカース硬さ試験機によって断面の径方向に順次測定
してゆくことによって知ることができる。Incidentally, and peak positions c 1 of the compressive residual stress, such as the position c 2 resulting in maximum stress when the spring used is known by analyzing the distortion of the material inside the metal crystals by using a stress measuring apparatus using the X-ray be able to. For peak position e 1 of the hardness, the cross-section of the cut material in the radial direction can be known by slide into successively measured in the radial direction of the cross section by the micro-Vickers hardness tester.
［実施例］ 第２図に模式的に示されたオースドローイング装置１
を用いて、母材としての鋼線Ａのドローイングを行な
う。鋼線Ａは一例として線径4mmのsup7であり、これを
線径3.8mmまで減面させる。減面率は約10％である。こ
の装置１は、加熱手段２と、冷却槽３と、ダイス４と、
冷却手段５と、引抜き用のチャック６などを備えてい
る。なお、加熱手段２と冷却槽３との間に冷却空気を噴
出する予備冷却手段７を設けてもよい。ダイス４のダイ
ス角αは15゜であるが、α＝45゜まで適用できる。Example An aus drawing apparatus 1 schematically shown in FIG.
Is used to draw a steel wire A as a base material. The steel wire A is sup7 having a wire diameter of 4 mm as an example, and is reduced to a wire diameter of 3.8 mm. The area reduction rate is about 10%. The apparatus 1 includes a heating means 2, a cooling tank 3, a die 4,
A cooling means 5 and a chuck 6 for pulling out are provided. Note that a pre-cooling unit 7 for ejecting cooling air may be provided between the heating unit 2 and the cooling tank 3. The die angle α of the die 4 is 15 °, but can be applied up to α = 45 °.
加熱手段２としては急速加熱が可能な通電加熱装置あ
るいは高周波誘導加熱装置が適するが、通常の加熱炉で
あってもよい。冷却槽３には、冷却媒体の一例として鋼
線ＡのMs点以上の温度（400〜500℃）の溶融鉛８が収容
されている。ダイス４はこの溶融鉛中に浸漬されてい
る。チャック６は鋼線Ａを長手方向に引っ張るものであ
るが、引っ張りと同時に軸回りに回転させることによっ
て、鋼線Ａをねじりながらダイス４を通過させるように
してもよい。冷却手段５は、ダイス４から引出された鋼
線ＡをMs点以下の温度まで急冷するのに使われ、一例と
して低温の空気を吹付けるノズルあるいは水等の冷却媒
体を吹付けるノズルなどを備えている。As the heating means 2, an electric heating device or a high-frequency induction heating device capable of rapid heating is suitable, but an ordinary heating furnace may be used. In the cooling tank 3, molten lead 8 having a temperature (400 to 500 ° C.) higher than the Ms point of the steel wire A is stored as an example of a cooling medium. The die 4 is immersed in the molten lead. Although the chuck 6 pulls the steel wire A in the longitudinal direction, the steel wire A may be rotated around the axis at the same time as the pulling, so that the steel wire A is passed through the die 4 while being twisted. The cooling means 5 is used for rapidly cooling the steel wire A drawn from the die 4 to a temperature of not more than the Ms point, and includes, for example, a nozzle for blowing low-temperature air or a nozzle for blowing a cooling medium such as water. ing.
チャック６によって鋼線Ａを引っ張りながら、加熱手
段２によって鋼線Ａをオーステナイト化温度（例えば95
0℃）まで急速加熱する。予備冷却手段７を通過するこ
とにより表面温度が600℃程度まで下がった鋼線Ａは冷
却槽３に導入されるとともに溶融鉛８によって過冷オー
ステナイト化温度（例えば400℃）まで急冷される。引
抜き速度は25mm/secである。While pulling the steel wire A by the chuck 6, the heating means 2 turns the steel wire A to an austenitizing temperature (for example, 95%).
(0 ° C). The steel wire A whose surface temperature has dropped to about 600 ° C. by passing through the pre-cooling means 7 is introduced into the cooling bath 3 and rapidly cooled by the molten lead 8 to a supercooled austenitizing temperature (for example, 400 ° C.). The drawing speed is 25 mm / sec.
ダイス４から引抜かれた鋼線Ａは、冷却手段５によっ
て直ちにMs点以下の温度まで急冷されることによって短
時間で組織が凍結される。しかも表層部にはダイス４か
らの引抜きによって加工硬化したマルテンサイト組織が
得られる。これを450℃・45分間の焼戻しを行なうこと
によって、第３図に示される硬さ分布のばね材料Ａ′が
得られる。The structure of the steel wire A drawn from the die 4 is immediately frozen by the cooling means 5 to a temperature equal to or lower than the Ms point, so that the structure is frozen in a short time. In addition, a martensite structure work-hardened by drawing from the die 4 is obtained on the surface layer. This is tempered at 450 ° C. for 45 minutes to obtain a spring material A ′ having a hardness distribution shown in FIG.
このような硬さ分布になる理由は、オースドローイン
グされた材料がもつ特有の焼入れ直後の硬さ分布と、焼
戻し軟化抵抗の相乗作用によるものと考えられる。第４
図に実線で示されるように、焼戻し軟化抵抗は表面側ほ
ど大となる。つまり焼戻しを行なった時に表面側ほど軟
化しにくい。これは、オースドローイングによる加工硬
化で表層部に歪んだ結晶が存在し、表層側ほど転位の量
が多くて金属同志を強く結びつけているからである。一
方、オースドローイング直後つまり焼入れ直後の硬さ分
布は、同第４図に破線で示すようにほぼ均一であるが、
最表面においては加工熱の発生による温度上昇により変
態生成物が生じたり、僅かながら脱炭が生じる傾向にあ
り、更に焼戻し時に外面側から加熱を受けるために内部
に比べて高い熱量にさらされるために最表面の硬さは僅
かに下がる。従って焼戻し後の硬さ分布は、前述したよ
うに表層部に硬さのピークが生じ、かつ表面の硬さが上
記ピーク値よりも小さいとともに表層部よりも中心側の
部分の硬さも上記ピーク値よりも小さくなる。The reason for such a hardness distribution is considered to be a synergistic effect of the specific hardness distribution immediately after quenching of the ausdrawn material and the tempering softening resistance. 4th
As shown by the solid line in the figure, the temper softening resistance becomes larger on the surface side. That is, when tempering is performed, the surface is harder to soften. This is because there is a crystal distorted in the surface layer due to work hardening by aus drawing, and the amount of dislocation is larger on the surface layer side, and the metals are strongly connected. On the other hand, the hardness distribution immediately after ausdrawing, that is, immediately after quenching is almost uniform as shown by the broken line in FIG.
At the outermost surface, there is a tendency for transformation products to occur due to the temperature rise due to the generation of processing heat, and a slight tendency to decarburize. However, the hardness of the outermost surface is slightly reduced. Therefore, as described above, the hardness distribution after tempering is such that the surface layer has a hardness peak, the surface hardness is smaller than the peak value, and the hardness at the center side of the surface layer is also the peak value. Smaller than.
上記硬さ分布をもつばね用材料は、表面が軟化してい
ることによって切欠き感受性が緩和されるとともに、耐
疲れ性の向上に最も効果のある表層部に硬さのピークが
ある。換言すると、硬さのピーク位置よりも中心側の部
分の硬さが下がっているから、表面部のみが軟化してい
る材料に比べると、同じ耐疲れ性であれば延性が大きい
分だけコイルばね等への成形が容易である。In the spring material having the above hardness distribution, notch sensitivity is reduced due to the softened surface, and a hardness peak is present in a surface layer most effective in improving fatigue resistance. In other words, since the hardness of the central portion is lower than the peak position of the hardness, compared to a material having only a softened surface portion, if the same fatigue resistance is used, the coil spring has a greater ductility than the material having the same fatigue resistance. Easy to mold into
第１図は本発明によるばね用材料の断面内硬さ分布を
模式的に表わしたものであり、硬さが変化し始める箇所
e0から表面までの距離をl1、硬さのピーク位置e1から表
面までの距離をl2としたとき、l1をl2の２倍以上にする
のが望ましい。なぜなら、第１図に２点鎖線で示したよ
うにe1がe0に近付くほどe0における硬度変化が急になっ
てe0付近に応力が集中しやすくなり、ここが疲労破壊の
起点になることがあるからである。硬さが変化し始める
箇所e0や硬さのピーク位置e1は、径方向に切断された材
料の断面を、マイクロビッカース硬さ試験機によって断
面の径方向に順次測定してゆくことによって知ることが
できる。硬さが変化し始める箇所e0は、測定精度や硬さ
のばらつき等を考慮すると、第３図に示されるように、
材料の中心から硬さのピークに向かって硬さの変化率が
距離1mm当たり50HMVを越える箇所（第３図において表面
から0.5mm付近）である。硬さのピーク位置e1は、断面
内で最大硬さを示す箇所である。本発明者らの研究によ
ると、l1≧2l2であれば硬さの変化点e0での応力集中が
充分に緩和され、しかも硬さのピーク値Ａと中心側部分
の硬さＢの差（Ａ−Ｂ）をHMV150以下とすることによっ
て、硬さの変化点e0が疲労破壊の起点になることを防止
できた。この図示例では表面の硬さＣが中心部の硬さＢ
よりも小さいが、ＣとＢよりも大きくてもよい。好まし
い硬さA,B,Cは、HMV350≦Ｃ≦HMV580,HMV350≦Ｂ≦HMV6
50,HMV20≦Ａ−Ｂ≦HMV150である。FIG. 1 schematically shows a hardness distribution in a cross section of a spring material according to the present invention, where a hardness starts to change.
Assuming that the distance from e 0 to the surface is l 1 and the distance from the hardness peak position e 1 to the surface is l 2 , it is desirable that l 1 be at least twice as large as l 2 . This is because, e 1 as shown by two-dot chain line in Figure 1 is likely hardness change steeper stress is concentrated in the vicinity of e 0 in more e 0 approaches e 0, here the starting point of fatigue fracture This is because it may be. The location e 0 where the hardness starts to change and the peak position e 1 of the hardness are known by sequentially measuring the cross section of the material cut in the radial direction in the radial direction of the cross section using a micro Vickers hardness tester. be able to. The location e 0 at which the hardness starts to change is, as shown in FIG. 3, in consideration of measurement accuracy, variation in hardness, and the like.
This is a location where the rate of change in hardness from the center of the material to the hardness peak exceeds 50 HMV per 1 mm of distance (around 0.5 mm from the surface in FIG. 3). Peak position e 1 of the hardness is a point showing the maximum hardness in the section. According to the study of the present inventors, if l 1 ≧ 2l 2 , the stress concentration at the change point e 0 of the hardness is sufficiently relaxed, and furthermore, the peak value A of the hardness and the hardness B of the central part are reduced. by difference of (a-B) and HMV150 less, change point e 0 hardness is prevented to become a starting point of fatigue fracture. In the illustrated example, the hardness C of the surface is the hardness B of the central part.
, But may be larger than C and B. Preferred hardness A, B, C is HMV350 ≦ C ≦ HMV580, HMV350 ≦ B ≦ HMV6
50, HMV20 ≦ AB ≦ HMV150.
上記ばね用材料Ａ′は、コイルばねに成形された後に
周知のショットピーング処理が施される。第５図に実線
ｍで示したように、ショットピーニングされた材料の内
部には、いわゆるクロッシングポイントc0を境に表面側
が圧縮の残留応力で、内部側が引っ張りの応力となる。
また圧縮残留応力が最大となるピーク位置c1の深さは一
般にクロッシングポイントc0の深さの半分位である。こ
のばね材料の曲げあるいはねじり応力分布は、同図に破
線ｎで示されるように中心側ほど応力が小さくなる。こ
のため、ばねとして使用される際の応力は、ｍとｎの合
力（線分ｇ）となり、最大応力を生じる位置c2はクロッ
シングポイントc0より少し内側にある。The above-mentioned spring material A 'is subjected to a well-known shot peening process after being formed into a coil spring. As indicated by the solid line m in FIG. 5, the interior of the shot peening material, surface bordering a so-called crossing points c 0 is the residual stress of compression, the internal side is tensile stress.
The depth of the peak position c 1 that compressive residual stress is maximum is generally about half of the depth of the crossing point c 0. In the bending or torsional stress distribution of the spring material, the stress becomes smaller toward the center as shown by a broken line n in FIG. For this reason, the stress when used as a spring is the combined force of m and n (line segment g), and the position c 2 where the maximum stress occurs is slightly inside the crossing point c 0 .
残留応力の観点からすると、耐疲れ性を左右するのは
材料表面からクロッシングポイントc0に至る圧縮残留応
力の分布状態とその領域での硬さである。これに対し、
材料の断面内硬さ分布の観点からするとから、耐疲れ性
を左右するのは材料表面からやや内側に入った箇所の硬
さである。このため、前述した硬さのピーク位置e1がc1
（圧縮残留応力が最大となる位置）からc2（使用時に最
大応力が生じる位置）の間にくるようにショットピーニ
ング前に調質を行なえば、耐疲れ性を向上させる上でき
わめて好結果が得られることにより、本発明の目的が達
成される。From the standpoint of the residual stress, to affect the resistance to fatigue resistance is hardness at that area and the distribution of compressive residual stress reaches the crossing point c 0 from the material surface. In contrast,
From the viewpoint of the hardness distribution in the cross section of the material, it is the hardness of a portion slightly inside from the material surface that determines the fatigue resistance. Therefore, the peak position e 1 of the hardness is c 1
If refining is performed before shot peening so that it is between (the position where the compressive residual stress is the maximum) and c 2 (the position where the maximum stress occurs during use), extremely good results can be achieved in improving fatigue resistance. The object of the present invention is achieved by being obtained.
具体的に言えば、一般的なクロッシングポイントc0の
深さは、線径4mmの弁ばねサイズで0.15〜0.25mm、線径1
2mmの懸架用ばねでも0.2〜0.3mmである。ばね使用時に
最大応力を生じる箇所c2はクロッシングポイントc0より
も僅かに内側、つまり線径12mmの時にはおおむね0.4mm
付近のところに生じる。一方、圧縮残留応力がピークと
なる位置c1の深さは一般的にクロッシングポイントc0の
約1/2であり、現行のショットピーニングでは最小で0.0
5mmが限界である。従って弁ばねサイズ（線径4mmから懸
架用ばねサイズ（線径12mm）の範囲で使われる場合に
は、第５図にハッチングで示したc1からc2間の領域は、
0.05〜0.4mmである。この範囲にe1に入るようにするに
は、最小値0.05mmに対して最大12mm（半径Ｒ＝６）の線
径ではl2/R＝0.05/6≒0.008が最小であり、また最大値
0.4mmに対して最小線径4mm（半径Ｒ＝２）ではl2/R＝0.
4/2＝0.20となる。これらのことから本発明では、実用
に供されるばねサイズで耐疲れ性に最も効果のある硬さ
のピーク位置e1の深さl2を、 0.008≦l2/R≦0.20の範囲に入れることを推奨する。Specifically, the general depth of the crossing point c 0 is, 0.15 to 0.25 mm in the valve spring size diameter 4 mm, diameter 1
Even a 2 mm suspension spring is 0.2-0.3 mm. The point c 2 where the maximum stress occurs when using a spring is slightly inside the crossing point c 0 , that is, approximately 0.4 mm when the wire diameter is 12 mm.
Occurs in the vicinity. On the other hand, the depth of the position c 1 that compressive residual stress has a peak is about 1/2 of the general crossing point c 0, a minimum in the current shot peening 0.0
5mm is the limit. Therefore, when used in the range of valve spring size (wire diameter 4 mm to suspension spring size (wire diameter 12 mm)), the area between c 1 and c 2 shown by hatching in FIG.
It is 0.05 to 0.4 mm. In order to fall within this range e 1 , for a wire diameter of a maximum of 12 mm (radius R = 6) against a minimum of 0.05 mm, l 2 /R=0.05/6＝0.008 is the minimum, and the maximum is
For a minimum wire diameter of 4 mm (radius R = 2) against 0.4 mm, l 2 / R = 0.
4/2 = 0.20. From these facts, in the present invention, the depth l 2 of the peak position e 1 of the hardness that is most effective in fatigue resistance at a spring size used for practical use is set in the range of 0.008 ≦ l 2 /R≦0.20. It is recommended that
第６図に弁ばねサイズでの疲労試験結果を示す。この
場合の素材はswosc（Si−Cr添加オイルテンパー線）を
用い、前述した条件でオースドローイングと焼戻しを行
なったものである。本発明によるばね用材料は、既存の
オイルテンパー線に比べて２倍ほど疲労強度が向上する
ことが確認された。同じく弁ばねサイズでの残留せん断
ひずみ（締付応力120Kgf/mm2,締付時間72hour）につい
ては、室温で1.0×10-4,80℃において７×10-4であり、
同一条件でのオイルテンパー線の残留せん断ひずみ（室
温で2.0×10-4,80℃で９×10-4）に比べて耐へたり性に
も優れている。FIG. 6 shows the results of a fatigue test with a valve spring size. The material used in this case is swosc (oil tempered wire with Si-Cr added) and is subjected to ausdrawing and tempering under the conditions described above. It has been confirmed that the spring material according to the present invention has twice as much fatigue strength as the existing oil-tempered wire. Similarly, the residual shear strain at the valve spring size (tightening stress 120 kgf / mm 2 , tightening time 72 hours) is 1.0 × 10 -4 at room temperature and 7 × 10 -4 at 80 ° C.
Excellent in sag resistance compared to the residual shear strain of oil-tempered wire under the same conditions (2.0 × 10 −4 at room temperature, 9 × 10 −4 at 80 ° C.).
上記実施例ではオースドローイングによる加工熱処理
と焼戻しによって所望の硬さ分布をもたせたが、これ以
外の方法によって前記硬さ分布を実現することもでき
る。例えば第７図に示されるように、冷間引抜き等の冷
間加工によって材料の表面部を加工硬化させたのちに、
高周波誘導加熱等の急速加熱によって短時間の表面焼戻
しを行なうことにより、中心部の硬さをほとんど変化さ
せずに表面部のみを軟化させるようにしてもよい。In the above embodiment, the desired hardness distribution is provided by the working heat treatment and tempering by aus drawing, but the hardness distribution can be realized by other methods. For example, as shown in FIG. 7, after work hardening the surface of the material by cold working such as cold drawing,
By performing surface tempering for a short time by rapid heating such as high-frequency induction heating, only the surface portion may be softened without substantially changing the hardness of the central portion.
［発明の効果］ 本発明によれば、ショットピーニングが行われるばね
用材料において、切欠き感受性を緩和できるだけでな
く、耐疲れ性に優れかつ延性が大きくコイルばね等への
成形が容易なばね用材料が得られる。[Effects of the Invention] According to the present invention, in a spring material subjected to shot peening, not only the notch sensitivity can be reduced, but also the fatigue resistance is excellent, the ductility is large, and the spring is easily formed into a coil spring or the like. The material is obtained.
第１図は本発明の一実施例によるばね材料の硬さ分布を
模式的に示す図、第２図はオースドローイングを実施す
るための装置の略縦断面図、第３図はオースドローイン
グと焼戻し後の材料の硬さを示す図、第４図は焼戻し軟
化抵抗と焼戻し後の硬さとの関係を示す図、第５図は残
留応力とばね使用時の応力の関係を示す図、第６図は弁
ばねサイズでの疲労試験結果を示す図、第７図は冷間加
工後の硬さ分布を示す図、第８図は普通熱処理を行なっ
た場合の硬さ分布を示す図、第９図は浸炭または窒化処
理による硬さ分布を示す図、第10図は表面部を軟化させ
た従来例の硬さ分布を示す図である。FIG. 1 is a view schematically showing a hardness distribution of a spring material according to an embodiment of the present invention, FIG. 2 is a schematic vertical sectional view of an apparatus for performing aus drawing, and FIG. 3 is aus drawing and tempering. FIG. 4 shows the relationship between the temper softening resistance and the hardness after tempering, FIG. 5 shows the relationship between residual stress and stress when a spring is used, and FIG. 6. FIG. 7 shows a fatigue test result in a valve spring size, FIG. 7 shows a hardness distribution after cold working, FIG. 8 shows a hardness distribution when ordinary heat treatment is performed, and FIG. FIG. 10 is a diagram showing a hardness distribution by carburizing or nitriding, and FIG. 10 is a diagram showing a hardness distribution of a conventional example in which the surface is softened.
───────────────────────────────────────────────────── フロントページの続き (72)発明者 東野 豊之 神奈川県横浜市磯子区新磯子町１番地 株式会社日発グループ中央研究所内 (56)参考文献 特開 昭53−113715（ＪＰ，Ａ) 特開 昭51−56759（ＪＰ，Ａ) 特開 平２−287223（ＪＰ，Ａ) ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Toyoyuki Higashino 1 Shinisogocho, Isogo-ku, Yokohama-shi, Kanagawa Pref. JP-A-51-56759 (JP, A) JP-A-2-287223 (JP, A)
Claims (2)
の硬さが上記ピーク値よりも小さくかつ表層部よりも中
心側の部分の硬さも上記ピーク値よりも小さい硬さ分布
となるように調質され、かつ、硬さのピーク位置e1が、
ショットピーニングによって付与される圧縮残留応力の
ピーク位置c1からばね使用時に最大応力を生じる位置c2
の間に入る硬さ分布となるように調質されたことを特徴
とするばね用材料。The surface distribution has a hardness peak, and the hardness of the surface is smaller than the peak value, and the hardness of the portion closer to the center than the surface layer has a hardness distribution smaller than the peak value. And the hardness peak position e 1 is
Position c 2 resulting in maximum stress at peak positions c 1 to the spring used in the compressive residual stresses imparted by shot peening
A spring material characterized in that it has been tempered to have a hardness distribution that falls between the two.
箇所e0から表面までの距離をl1、硬さのピーク位置e1か
ら表面までの距離をl2とした時、l1≧2l2である特許請
求の範囲第１項記載のばね用材料。2. In the above hardness distribution, when the distance from the point e 0 where the hardness starts to change to the surface is l 1 , and the distance from the hardness peak position e 1 to the surface is l 2 , l 1 ≧ 2. The spring material according to claim 1, wherein the material is 2l2.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63116365A JP2716141B2 (en) | 1988-05-13 | 1988-05-13 | Spring material |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63116365A JP2716141B2 (en) | 1988-05-13 | 1988-05-13 | Spring material |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH01287222A JPH01287222A (en) | 1989-11-17 |
| JP2716141B2 true JP2716141B2 (en) | 1998-02-18 |
Family
ID=14685161
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP63116365A Expired - Fee Related JP2716141B2 (en) | 1988-05-13 | 1988-05-13 | Spring material |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2716141B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001304369A (en) * | 2000-04-27 | 2001-10-31 | Tsubaki Nakashima Co Ltd | Carburized-quenched screw shaft for return tube type ball screw |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5156759A (en) * | 1974-11-15 | 1976-05-18 | Hitachi Metals Ltd | Onkanhikinukihoho oyobi sochi |
| FR2394611A1 (en) * | 1977-03-14 | 1979-01-12 | Sodetal | PROCESS FOR OBTAINING AN ELONGATED HARD STEEL ELEMENT |
| JPS62260015A (en) * | 1986-05-02 | 1987-11-12 | Sumitomo Electric Ind Ltd | Spring having excellent resistance to fatigue and production thereof |
-
1988
- 1988-05-13 JP JP63116365A patent/JP2716141B2/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001304369A (en) * | 2000-04-27 | 2001-10-31 | Tsubaki Nakashima Co Ltd | Carburized-quenched screw shaft for return tube type ball screw |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH01287222A (en) | 1989-11-17 |
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