JP4374306B2 - Connecting rods with excellent fatigue characteristics and methods for improving the fatigue characteristics - Google Patents
Connecting rods with excellent fatigue characteristics and methods for improving the fatigue characteristics Download PDFInfo
- Publication number
- JP4374306B2 JP4374306B2 JP2004295871A JP2004295871A JP4374306B2 JP 4374306 B2 JP4374306 B2 JP 4374306B2 JP 2004295871 A JP2004295871 A JP 2004295871A JP 2004295871 A JP2004295871 A JP 2004295871A JP 4374306 B2 JP4374306 B2 JP 4374306B2
- Authority
- JP
- Japan
- Prior art keywords
- connecting rod
- column
- fatigue
- residual stress
- fatigue characteristics
- 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
Images
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
Landscapes
- Shafts, Cranks, Connecting Bars, And Related Bearings (AREA)
Description
本発明は、疲労特性に優れたコンロッドおよびその疲労特性向上方法に関する。
具体的には、自動車などの内燃機関に用いられる疲労特性に優れたコンロッドおよびその疲労特性向上方法に関する。
The present invention relates to a connecting rod excellent in fatigue characteristics and a method for improving the fatigue characteristics thereof.
Specifically, the present invention relates to a connecting rod having excellent fatigue characteristics used for an internal combustion engine such as an automobile and a method for improving the fatigue characteristics.
自動車等の内燃機関などのピストンとクランクシャフトとを連接するコンロッドには、繰り返し荷重が働くため、疲労強度の向上が求められており、従来からコンロッドの強化方法について、種々の提案がなされている。
＜加工による強化＞
例えば、特許文献１には、Ａｒ１以下２００℃以上の温度域で耐力・疲労が要求される箇所に追加工（温間鍛造）して、加工により転位を導入して転位強化および時効硬化により強度を増し、疲労強度を向上する方法に関する発明が開示されている。
しかし、同文献に記載の発明は、低温で約２０％の加工が必要なため、鍛造機が必須となり、設備コストが高いという問題があった。
Connecting rods that connect pistons and crankshafts of internal combustion engines, such as automobiles, are subjected to repeated loads, so that improvement in fatigue strength is required. Conventionally, various methods for reinforcing connecting rods have been proposed. .
<Strengthening by processing>
For example, in
However, the invention described in the same document has a problem that a forging machine is indispensable and equipment cost is high because processing of about 20% is necessary at low temperature.
＜変態および圧縮残留応力による強化＞
例えば、特許文献２には、マルテンサイト変態温度が６００℃以上である鋼を用いコンロッド形状にしたあと焼入して、表面がマルテンサイトで内部がベイナイトないしはフェライト＋パーライト組織にし、ショットブラスト、ショットピーニング等の表面圧縮加工を行なって表面を強化し、内部は柔らかくする方法に関する発明が開示されている。この発明により、必要な強度を保ったまま、ドリル加工性を向上させることができる。
しかしながら、同文献に記載の発明は、焼入による曲がり等の変形が大きく冷間形状補正が手間であること、および焼入ままでは耐力（例えば、０．０５％耐力）が低く、座屈強度の確保が困難であるという問題があるうえ、焼き戻しを行なうと耐力は上昇するが、工程が増えるためコスト上昇を招いていた。
<Strengthening by transformation and compressive residual stress>
For example,
However, the invention described in the same document has a large deformation such as bending due to quenching, and the cold shape correction is troublesome, and the proof stress (for example, 0.05% proof stress) is low and the buckling strength is low. In addition, there is a problem in that it is difficult to ensure, and tempering increases the yield strength, but increases the number of processes, which increases the cost.
＜圧縮残留応力による疲労強度向上＞
例えば、特許文献３には、強度なショットピーニング処理であるいわゆるハードショットと研削を併用して圧縮残留応力を導入し、疲労強度向上を図る方法に関する発明が開示されている。
しかし、この発明の方法は、ハードショットのみでは表面が荒れ、かえって疲労寿命を低下させる場合もあるため、研削との併用が必須であり、このため、研削を伴わない部品、熱鍛ままの部品には適用できなかった。
For example,
However, since the method of the present invention may roughen the surface only with hard shots and may reduce the fatigue life, it is essential to use it together with grinding. Could not be applied.
本発明は、前述のような従来技術の問題点を解決し、疲労特性に優れたコンロッドおよびその疲労強度向上方法を提供するものであり、具体的には下記の３点を課題とする。
１）大きな圧縮残留応力を付加することができる。
２）肌荒れが少ない。
３）簡便な強化方法である。
The present invention solves the problems of the prior art as described above, and provides a connecting rod excellent in fatigue characteristics and a method for improving the fatigue strength thereof. Specifically, the following three points are problems.
1) A large compressive residual stress can be applied.
2) Less rough skin.
3) A simple strengthening method.
本発明は、前述の課題を解決するために鋭意検討の結果なされたものであり、コンロッドのコラムに超音波打撃処理を施して、コラム表層に圧縮残留応力を導入することによって、疲労特性に優れたコンロッドおよびその疲労強度向上方法を提供するものであり、その要旨とするところは、特許請求の範囲に記載した通りの下記内容である。
（１）質量％で、Ｃ：０．１〜０．８％、Ｓｉ：０．０５〜２．５％、Ｍｎ：０．２〜３％、Ａｌ：０．００５〜０．１％、Ｎ：０．００１〜０．０２％を含有し、残部がＦｅおよび不可避的不純物からなり、引張強さが７００ＭＰａ以上の鋼材からなるコンロッドであって、超音波打撃処理によって該コンロッドのコラム表層に導入された圧縮残留応力が前記鋼材の引張強さの５０〜８０％であり、前記コラムのリム部の平均表面粗度が０．５μｍ以下であることを特徴とする疲労特性に優れたコンロッド。
（２）質量％で、Ｃ：０．１〜０．８％、Ｓｉ：０．０５〜２．５％、Ｍｎ：０．２〜３％、Ａｌ：０．００５〜０．１％、Ｎ：０．００１〜０．０２％を含有し、残部がＦｅおよび不可避的不純物からなり、引張強さが７００ＭＰａ以上の鋼材からなるコンロッドの疲労特性向上方法であって、前記コンロッドのコラム表層に導入された圧縮残留応力が前記鋼材の引張強さの５０〜８０％、前記コラムのリム部の平均表面粗度が０．５μｍ以下になるように、振動数１０〜６０ｋＨｚ、振幅０．３〜５０μｍで振動する超音波振動端子で前記コンロッドのコラムの表面を打撃しながら走査することを特徴とするコンロッドの疲労特性向上方法。
（３）前記超音波振動端子による打撃範囲を、前記コラムの首部におけるリム部の表面とすることを特徴とする（２）に記載のコンロッドの疲労特性向上方法。
The present invention has been made as a result of intensive studies to solve the above-mentioned problems, and is excellent in fatigue characteristics by applying ultrasonic impact treatment to the column of the connecting rod and introducing compressive residual stress into the surface layer of the column. The connecting rod and its fatigue strength improving method are provided and the gist of the connecting rod is as follows.
(1) By mass%, C: 0.1-0.8%, Si: 0.05-2.5%, Mn: 0.2-3%, Al: 0.005-0.1%, N : A connecting rod containing 0.001 to 0.02%, the balance being made of Fe and inevitable impurities, and a steel material having a tensile strength of 700 MPa or more, introduced into the column surface of the connecting rod by ultrasonic hitting treatment Ri 50-80% der compressive residual stress is tensile strength of the steel is, connecting rod average surface roughness of the rim portion of the column and excellent fatigue properties, characterized in der Rukoto below 0.5μm .
(2 ) By mass%, C: 0.1-0.8%, Si: 0.05-2.5%, Mn: 0.2-3%, Al: 0.005-0.1%, N : A method for improving the fatigue properties of a connecting rod comprising 0.001 to 0.02%, the balance being Fe and inevitable impurities, and a steel material having a tensile strength of 700 MPa or more , introduced into the column surface of the connecting rod So that the compressed residual stress is 50 to 80% of the tensile strength of the steel material and the average surface roughness of the rim portion of the column is 0.5 μm or less, the frequency is 10 to 60 kHz, and the amplitude is 0.3 to 50 μm. A method for improving the fatigue characteristics of a connecting rod, comprising: scanning the surface of the column of the connecting rod while striking the surface of the connecting rod with an ultrasonic vibration terminal that vibrates.
( 3 ) The method for improving the fatigue characteristics of a connecting rod according to ( 2 ), wherein the striking range by the ultrasonic vibration terminal is the surface of the rim portion at the neck of the column.
本発明により、コンロッドのコラムに超音波打撃処理を施して、コラム表層に圧縮残留応力を導入することによって、疲労特性に優れ、肌荒れが少ないコンロッドおよび簡便な疲労強度向上方法を提供することができ、このため、疲労破壊することがなくなり部品の信頼性が増す。
例えば、図６に示すように、母材強度が８１０ＭＰａの鋼材に対して本発明の条件で超音波打撃処理を施したところ、圧縮残留応力が４０５ＭＰａ以上の場合に、４４０ＭＰａ以上の疲労強度が確保できる。
また、強化分相応の部品の軽量化が可能となり燃費向上・コスト削減に寄与するなど、産業上有用な著しい効果を奏する。
According to the present invention, by applying ultrasonic striking treatment to the column of the connecting rod and introducing compressive residual stress into the column surface layer, it is possible to provide a connecting rod having excellent fatigue characteristics and less rough skin and a simple method for improving fatigue strength. For this reason, fatigue failure is eliminated and the reliability of the parts is increased.
For example, as shown in FIG. 6, when a steel material having a base material strength of 810 MPa is subjected to an ultrasonic impact treatment under the conditions of the present invention, a fatigue strength of 440 MPa or more is secured when the compressive residual stress is 405 MPa or more. it can.
In addition, it is possible to reduce the weight of the parts corresponding to the strengthened parts and contribute to the improvement of fuel consumption and cost reduction.
本発明を実施するための最良の形態について図１乃至図４を用いて詳細に説明する。
図１は、本発明の対象であるコンロッドを例示する斜視図である。
図１において、１は小端部、２は大端部、３は首部、４はコラムを示す。
自動車の内燃機関に用いられるコンロッドは、エンジンの燃焼室で起こる爆発を回転運動に変えるための重要部品であり、爆発毎に高い応力を受けるため、疲労特性の確保が重要な課題であり、この疲労強度向上のために、コンロッドの高強度化が望まれている。
しかしながら、コンロッドの大端部・小端部は切削加工を行なうため、切削性を確保するため強度をあまり上げることができない。
そこで、本発明等は、高強度化と切削性という、相反する要求を満足させるため、強度を上げずに疲労強度のみを向上する方法を検討した結果、超音波振動する端子で鋼材を打撃することにより、コンロッドのコラム表面に大きな圧縮の残留応力を付与し、かつショットピーニングと同様表面を塑性加工することにより加工硬化し、コンロッドの疲労強度の大幅向上が可能であることを見出した。
The best mode for carrying out the present invention will be described in detail with reference to FIGS.
FIG. 1 is a perspective view illustrating a connecting rod that is an object of the present invention.
In FIG. 1, 1 is a small end, 2 is a large end, 3 is a neck, and 4 is a column.
Connecting rods used in automobile internal combustion engines are an important part for turning the explosion that occurs in the combustion chamber of the engine into a rotational motion. Since high stress is applied to each explosion, securing fatigue characteristics is an important issue. In order to improve the fatigue strength, it is desired to increase the strength of the connecting rod.
However, since the large end portion and the small end portion of the connecting rod are machined, the strength cannot be increased so much in order to secure the machinability.
In view of this, the present invention and the like have studied the method of improving only the fatigue strength without increasing the strength in order to satisfy the conflicting demands of high strength and machinability. As a result, the steel material is hit with a terminal that vibrates ultrasonically. As a result, it was found that a large compressive residual stress was applied to the column surface of the connecting rod, and the surface of the connecting rod was worked and hardened by plastic working as in shot peening, so that the fatigue strength of the connecting rod could be greatly improved.
本発明のコンロッドは、質量％で、Ｃ：０．１〜０．８％、Ｓｉ：０．０５〜２．５％、Ｍｎ：０．２〜３％、Ａｌ：０．００５〜０．１％、Ｎ：０．００１〜０．０２％を含有し、残部がＦｅおよび不可避的不純物からなり、引張強さが７００ＭＰａ以上の鋼材からなるコンロッドであって、該コンロッドのコラム表層における圧縮残留応力が前記鋼材の引張強さの５０〜８０％であることを特徴とする。
なお、本発明においては、コンロッドに用いる鋼材の組織や処理工程は問わず、フェライト−パ−ライト鋼、ベイナイト鋼、マルテンサイト鋼など、いずれの組織の鋼材にも適用できるうえ、熱間鍛造非調質鋼や調質鋼だけでなく鋳造品にも適用できる。
The connecting rod of the present invention is mass%, C: 0.1 to 0.8%, Si: 0.05 to 2.5%, Mn: 0.2 to 3%, Al: 0.005 to 0.1. %, N: 0.001 to 0.02%, with the balance being Fe and inevitable impurities, and a connecting rod made of a steel material having a tensile strength of 700 MPa or more, the compressive residual stress in the column surface of the connecting rod Is 50 to 80% of the tensile strength of the steel material.
In the present invention, the structure of steel used for the connecting rod and the treatment process are not limited, and it can be applied to steels having any structure such as ferrite-pearlite steel, bainite steel, martensite steel, etc. It can be applied not only to tempered steel and tempered steel, but also to cast products.
本発明の限定理由を以下に説明する。
＜鋼材成分の限定理由＞
Ｃは、鋼を強化するのに有効な元素であるが、０．１％未満では充分な強度が得られない。一方、過多に添加すると靭性が低下するため、添加量の上限を０．８％とする。
Ｓｉは、鋼の強化元素として有効であるが、０．０５％未満ではその効果がない。一方、過多に添加すると靭性および被削性が低下するため、添加量の上限を２．５％とする。
Ｍｎは、鋼の強化に有効な元素であるが、０．２％未満では充分な効果が得られない。一方、過多に添加すると靭性および被削性が低下するため、添加量の上限を２％とする。
Ａｌは、鋼の脱酸および結晶粒の微細化のために有効な元素であるが、０．００５％未満ではその効果がない。一方、過多に添加すると被削性が低下するため、添加量の上限を０．１％とする。
Ｎは、Ｖ炭窒化物やＮｂ炭窒化物を生成し析出強化のために必要な元素であるが、０．００１％未満では充分な効果が得られない。一方、過多に添加すると靭性が劣化するため、添加量の上限を０．０２％とする。
これらの元素以外にも、固溶強化が期待できる元素としてＣｒ，Ｎｉ，Ｍｏ，Ｃｕが、析出強化が期待できる元素としてＴｉ，Ｖ，Ｎｂが、被削性を向上させる元素として、Ｐｂ，Ｓ，Ｂｉ等が考えられるが、特に限定はしない。
The reason for limiting the present invention will be described below.
<Reason for limiting steel components>
C is an element effective for strengthening steel, but if it is less than 0.1%, sufficient strength cannot be obtained. On the other hand, if added excessively, toughness decreases, so the upper limit of the amount added is 0.8%.
Si is effective as a steel strengthening element, but less than 0.05% has no effect. On the other hand, if added in excess, the toughness and machinability deteriorate, so the upper limit of the amount added is 2.5%.
Mn is an element effective for strengthening steel, but if it is less than 0.2%, a sufficient effect cannot be obtained. On the other hand, if added in excess, the toughness and machinability deteriorate, so the upper limit of the amount added is 2%.
Al is an element effective for deoxidation of steel and refinement of crystal grains, but if it is less than 0.005%, there is no effect. On the other hand, if added in excess, the machinability decreases, so the upper limit of the amount added is 0.1%.
N is an element necessary for precipitation strengthening by generating V carbonitride and Nb carbonitride, but if it is less than 0.001%, sufficient effects cannot be obtained. On the other hand, if added excessively, the toughness deteriorates, so the upper limit of the amount added is 0.02%.
In addition to these elements, Cr, Ni, Mo, and Cu can be expected as solid solution strengthening, Ti, V, and Nb can be expected as precipitation strengthening, and Pb, S as elements that improve machinability. , Bi, etc. are conceivable, but not particularly limited.
＜強度および圧縮残留応力の限定理由＞
強度は７００ＭＰａ以下の鋼材では、超音波処理の処理部表面の圧縮残留応力の下限規定である５０％では十分な疲労強度向上効果が得られないため、その下限値を７００ＭＰａとした。
本発明の超音波処理の処理部表面における残留応力の限定理由を以下に示す。
７００ＭＰａ以上の強度を持つ鋼材において、引張強さの５０％以下の圧縮残留応力では十分な疲労強度向上が認められないこと、および、引張強さの８０％以上の圧縮残留応力を付与することは、本発明では困難であることから、その上限を８０％とした。
<Reason for limitation of strength and compressive residual stress>
In steel materials having a strength of 700 MPa or less, a sufficient fatigue strength improvement effect cannot be obtained at 50%, which is the lower limit of the compressive residual stress on the surface of the ultrasonic treated portion, so the lower limit was set to 700 MPa.
The reasons for limiting the residual stress on the surface of the treated portion of the ultrasonic treatment of the present invention are shown below.
In a steel material having a strength of 700 MPa or more, a sufficient fatigue strength improvement cannot be observed with a compressive residual stress of 50% or less of the tensile strength, and a compressive residual stress of 80% or more of the tensile strength is imparted. Since it is difficult in the present invention, the upper limit was made 80%.
＜表面粗度の限定理由＞
本発明においてはコンロッドの表面粗度は問わないが、コラムのリム部の平均表面粗度が０．５μｍ以下であることが好ましい。
コラムのリム部の平均表面粗度が０．５μｍ以下とすることによって、肌荒れが少なく、疲労強度を著しく向上させることができる。
<Reason for limiting surface roughness>
In the present invention, the surface roughness of the connecting rod is not limited, but the average surface roughness of the rim portion of the column is preferably 0.5 μm or less.
By setting the average surface roughness of the rim portion of the column to 0.5 μm or less, there is little skin roughness and the fatigue strength can be remarkably improved.
図２乃至図４は、本発明のコンロッドの疲労強度向上方法の実施形態を例示する図である。
図２乃至図４において、１は小端部、２は大端部、３は首部、４はコラム、５はリム部、６は超音波振動端子を示す。
図２は、本発明のコンロッドの実施形態を例示する図であり、上段が平面図を示し、下段が断面図を示している。
コンロッドのコラム４は繰り返し荷重を受けることによって、特に小端部１および大端部２の首部３が最も疲労き裂が生じ易い。
そこで、本発明におけるコンロッドの疲労特性向上方法は、振動数１０〜６０ｋＨｚ、振幅０．３〜５０μｍで振動する超音波振動端子で前記コンロッドのコラム４の表面を打撃しながら走査することを特徴とする。
超音波振動子の振動数を１０〜６０ｋＨｚと限定したのは、鋼材に与えられる圧縮の残留応力がこの領域で大きくなるからである。同様に、超音波振動するピン先端の振幅を０．３μｍ以上と限定したのも、これ以下の振幅では十分な圧縮残留応力を鋼材に与えることができないからである。振幅は大きいほど残留応力が増すが、５０μｍ以上では塑性変形が大きくなり過ぎ、部品の寸法精度が低下するとともに表面粗度も増大し、疲労強度も低下するため、振幅の上限を５０μｍに限定する。
2 to 4 are diagrams illustrating an embodiment of the connecting rod fatigue strength improving method of the present invention.
2 to 4, 1 is a small end portion, 2 is a large end portion, 3 is a neck portion, 4 is a column, 5 is a rim portion , and 6 is an ultrasonic vibration terminal.
FIG. 2 is a diagram illustrating an embodiment of the connecting rod of the present invention, in which the upper stage shows a plan view and the lower stage shows a cross-sectional view.
The column 4 of the connecting rod is subjected to repeated loads, so that fatigue cracks are most likely to occur particularly in the
Therefore, the method for improving the fatigue characteristics of the connecting rod in the present invention is characterized in that scanning is performed while striking the surface of the column 4 of the connecting rod with an ultrasonic vibration terminal that vibrates at a frequency of 10 to 60 kHz and an amplitude of 0.3 to 50 μm. To do.
The reason why the frequency of the ultrasonic vibrator is limited to 10 to 60 kHz is that the compressive residual stress applied to the steel material increases in this region. Similarly, the amplitude of the tip of the pin that vibrates ultrasonically is limited to 0.3 μm or more because sufficient compressive residual stress cannot be applied to the steel material with an amplitude below this. Residual stress increases as the amplitude increases, but plastic deformation becomes too large at 50 μm or more, the dimensional accuracy of the parts decreases, the surface roughness increases, and the fatigue strength also decreases, so the upper limit of the amplitude is limited to 50 μm. .
図３は、本発明におけるコンロッドのコラムの断面図であり、図２におけるＡ矢視図である。
図３に示すように、コラム４の首部３におけるリム部５の表面を超音波振動端子６を矢印の方向に移動させながら打撃処理を行うことが好ましい。コラム４の首部３におけるリム部５が、最も疲労き裂が生じ易い箇所であり、この部分を選択的に超音波打撃処理を行うことによって、コンロッドの疲労強度をさらに向上させることができる。
FIG. 3 is a cross-sectional view of the column of the connecting rod in the present invention, and is a view taken in the direction of arrow A in FIG.
As shown in FIG. 3, it is preferable to perform a striking process while moving the ultrasonic vibration terminal 6 in the direction of the arrow on the surface of the rim portion 5 in the
図４は、本発明のコンロッドの疲労強度向上方法に用いる超音波振動端子を例示する図である。
本発明においては、超音波振動端子の形状は問わないが、前述のように打撃処理部の表面粗度を０．５μｍ以下にするためには、図４に示すように、超音波振動端子６の先端部の半径を５ｍｍ程度に大きくし、また、超音波振動端子６の疲労き裂の入る方向に対して直角方向に往復させて走査することが好ましい。
これは、超音波振動端子６による処理により導入される圧縮残留応力には異方性があり、走査の方向に、より強い圧縮残留応力が付与されるからである。超音波打撃ピン先端の形状は、半球状、蒲鉾状が考えられるが特に限定しない。
なお、コンロッドの疲労き裂は、コラムの大小端近傍に発生することが多く、この部分を重点的に超音波処理するとよい。特に首部側面の見切り線近傍は、鍛造時の巻きこみ疵等応力集中を生じるノッチが存在している可能性があるため、首部側面の見切り線近傍への処理が効果的である。また、その他の疲労き裂発生場所として冷間矯正（コイニング）端部が挙げられる。この部位は引張残留応力が発生しており、疲労き裂の発生しやすい場所である。この部位を処理することにより、引張残留応力を圧縮残留応力に変えることが可能である。
FIG. 4 is a diagram illustrating an ultrasonic vibration terminal used in the connecting rod fatigue strength improving method of the present invention.
In the present invention, the shape of the ultrasonic vibration terminal is not limited, but as described above, in order to reduce the surface roughness of the hitting treatment portion to 0.5 μm or less, as shown in FIG. It is preferable to increase the radius of the tip of the oscillating member to about 5 mm, and to reciprocate in a direction perpendicular to the direction in which the fatigue crack of the ultrasonic vibration terminal 6 enters.
This is because the compressive residual stress introduced by the processing by the ultrasonic vibration terminal 6 is anisotropic, and a stronger compressive residual stress is applied in the scanning direction. The shape of the tip of the ultrasonic striking pin may be a hemispherical shape or a bowl shape, but is not particularly limited.
Note that the fatigue crack of the connecting rod often occurs in the vicinity of the large and small ends of the column, and this portion is preferably subjected to ultrasonic treatment mainly. In particular, the vicinity of the parting line on the side surface of the neck part may have a notch that causes stress concentration such as a winding wrinkle at the time of forging. Therefore, the processing near the parting line on the side face of the neck part is effective. Another fatigue crack occurrence location is a cold straightening (coining) end. This region is where tensile residual stress is generated and fatigue cracks are likely to occur. By treating this part, it is possible to change the tensile residual stress to the compressive residual stress.
表１に示す成分の鋼から、図５に示すコンロッドの疲労を模した平面曲げ試験片（ＪＩＳ Ｚ ２２７５ １号試験片、ｂ＝２０ｍｍ、Ｒ＝３０ｍｍ、ｔ＝２ｍｍ）を切り出した。
この試験片に本発明の超音波処理を施したもの、および無処理ないしは範囲外の処理を施した比較材を用意し、両振り平面曲げ疲労試験を行ない疲労強度を求めた。結果を表２に示す。
超音波打撃処理は、図５に示すように、試験片中央のくびれ部分について裏表行なった。この時の端子の形状は、先端の曲率半径５ｍｍ、幅３０ｍｍの蒲鉾状端子で行なった結果を表２に示す。
表２中の残留応力測定値は、疲労試験を行っていない試験片を別途用意し接合部表層の残留応力を測定したものである。なお、残留応力の測定はＸ線を用いて行ない、回折Ｘ線の強度を測定しピーク強度の半値幅から求めている。
超音波打撃処理無しの比較例は、引張強度の１／２未満の疲労強度しか得られなかった。
一方、適正な超音波打撃処理を行った発明例は、引張り強さの５０〜８０％の圧縮残留応力が導入されて、疲労強度が向上することが判る。
なお、打撃処理部の平均表面粗度を測定したところ、発明例においては０．５μｍ以下であっが、比較例では０．５μｍを超えていた。
以上のことから、本発明は比較例に比べ、大幅な疲労強度向上が認められ、有効であることが確認された。
A specimen subjected to the ultrasonic treatment of the present invention and a comparative material subjected to no treatment or treatment outside the range were prepared, and a double-bending plane bending fatigue test was performed to determine fatigue strength. The results are shown in Table 2.
As shown in FIG. 5, the ultrasonic striking treatment was performed on both sides of the constricted portion at the center of the test piece. The shape of the terminal at this time is shown in Table 2 as a result obtained by using a hook-shaped terminal having a radius of curvature of 5 mm at the tip and a width of 30 mm.
The residual stress measurement values in Table 2 are obtained by separately preparing a test piece that has not been subjected to a fatigue test and measuring the residual stress of the joint surface layer. The residual stress is measured using X-rays, and the intensity of diffracted X-rays is measured and obtained from the half-value width of the peak intensity.
Comparative Example ultrasonic striking treatment no Shino did only less than half of the fatigue strength of the tensile strength obtained.
On the other hand, it can be seen that, in the invention example in which an appropriate ultrasonic striking treatment has been performed, the fatigue strength is improved by introducing a compressive residual stress of 50 to 80% of the tensile strength.
In addition, when the average surface roughness of the hit | damage process part was measured, although it was 0.5 micrometer or less in the invention example, it exceeded 0.5 micrometer in the comparative example.
From the above, it was confirmed that the present invention was effective as a result of a significant improvement in fatigue strength as compared with the comparative example.
１ 小端部
２ 大端部
３ 首部
４ コラム
５ リム部
６ 超音波振動端子（半球状先端）
７ 超音波振動端子（蒲鉾状先端）
1
7 Ultrasonic vibration terminal (hook tip)
Claims (3)
Ｃ：０．１〜０．８％、
Ｓｉ：０．０５〜２．５％、
Ｍｎ：０．２〜３％、
Ａｌ：０．００５〜０．１％、
Ｎ：０．００１〜０．０２％
を含有し、残部がＦｅおよび不可避的不純物からなり、引張強さが７００ＭＰａ以上の鋼材からなるコンロッドであって、超音波打撃処理によって該コンロッドのコラム表層に導入された圧縮残留応力が前記鋼材の引張強さの５０〜８０％であり、前記コラムのリム部の平均表面粗度が０．５μｍ以下であることを特徴とする疲労特性に優れたコンロッド。 % By mass
C: 0.1-0.8%
Si: 0.05 to 2.5%,
Mn: 0.2-3%,
Al: 0.005 to 0.1%,
N: 0.001 to 0.02%
And the balance consisting of Fe and inevitable impurities, and a tensile strength of 700 MPa or more steel rod, the compressive residual stress introduced into the column surface of the connecting rod by ultrasonic striking treatment 50-80% der tensile strength is, connecting rod average surface roughness of the rim portion of the column and excellent fatigue properties, characterized in der Rukoto below 0.5 [mu] m.
Ｃ：０．１〜０．８％、
Ｓｉ：０．０５〜２．５％、
Ｍｎ：０．２〜３％、
Ａｌ：０．００５〜０．１％、
Ｎ：０．００１〜０．０２％
を含有し、残部がＦｅおよび不可避的不純物からなり、引張強さが７００ＭＰａ以上の鋼材からなるコンロッドの疲労特性向上方法であって、前記コンロッドのコラム表層に導入された圧縮残留応力が前記鋼材の引張強さの５０〜８０％、前記コラムのリム部の平均表面粗度が０．５μｍ以下になるように、振動数１０〜６０ｋＨｚ、振幅０．３〜５０μｍで振動する超音波振動端子で前記コンロッドのコラムの表面を打撃しながら走査することを特徴とするコンロッドの疲労特性向上方法。 % By mass
C: 0.1-0.8%
Si: 0.05 to 2.5%,
Mn: 0.2-3%,
Al: 0.005 to 0.1%,
N: 0.001 to 0.02%
And the balance is made of Fe and inevitable impurities, and the tensile strength of the connecting rod is made up of 700 MPa or more steel material, the compressive residual stress introduced into the column surface layer of the connecting rod of the steel material The ultrasonic vibration terminal that vibrates at a frequency of 10 to 60 kHz and an amplitude of 0.3 to 50 μm so that the tensile strength is 50 to 80% and the average surface roughness of the rim portion of the column is 0.5 μm or less. A method for improving the fatigue characteristics of a connecting rod, wherein the scanning is performed while striking the surface of the column of the connecting rod.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2004295871A JP4374306B2 (en) | 2004-10-08 | 2004-10-08 | Connecting rods with excellent fatigue characteristics and methods for improving the fatigue characteristics |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2004295871A JP4374306B2 (en) | 2004-10-08 | 2004-10-08 | Connecting rods with excellent fatigue characteristics and methods for improving the fatigue characteristics |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2006104553A JP2006104553A (en) | 2006-04-20 |
| JP4374306B2 true JP4374306B2 (en) | 2009-12-02 |
Family
ID=36374625
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2004295871A Expired - Fee Related JP4374306B2 (en) | 2004-10-08 | 2004-10-08 | Connecting rods with excellent fatigue characteristics and methods for improving the fatigue characteristics |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP4374306B2 (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100894499B1 (en) | 2008-05-14 | 2009-04-22 | (주)디자인메카 | The bearing processing system using an ultrasonic nano crystal surface modifier and processing method using the same |
| JP6226814B2 (en) * | 2014-05-22 | 2017-11-08 | 株式会社神戸製鋼所 | Manufacturing method of welded structure |
| US20230105814A1 (en) * | 2020-02-05 | 2023-04-06 | Mitsubishi Materials Corporation | Method for manufacturing cutting tool |
| CN112231953A (en) * | 2020-10-14 | 2021-01-15 | 西安热工研究院有限公司 | Method for improving fatigue strength of plug seat of emergency diesel engine of nuclear power station |
-
2004
- 2004-10-08 JP JP2004295871A patent/JP4374306B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JP2006104553A (en) | 2006-04-20 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| EP1803831B1 (en) | Nitrocarburized microalloyed steel member | |
| KR20060046214A (en) | High-strength steel for large-scaled forging, and crankshaft | |
| US20120318409A1 (en) | Solid stabilizer, steel material for solid stabilizer, and manufacturing method of solid stabilizer | |
| CN100516268C (en) | High strength machine parts and shaft excellent in fatigue characteristics, and method for improving fatigue characteristics thereof | |
| JP2017122500A (en) | Large-sized crank shaft | |
| JP5343760B2 (en) | Tempered soft nitriding parts | |
| KR101547015B1 (en) | High strength large steel forging | |
| KR101928680B1 (en) | Non-tempered soft-nitrided component | |
| JP4374306B2 (en) | Connecting rods with excellent fatigue characteristics and methods for improving the fatigue characteristics | |
| JP3876384B2 (en) | High strength connecting rod and manufacturing method thereof | |
| JP4436225B2 (en) | High-strength mechanical parts with excellent fatigue characteristics and methods for improving the fatigue characteristics | |
| JP6477904B2 (en) | Crankshaft rough profile, nitrided crankshaft, and method of manufacturing the same | |
| JP2001254143A (en) | Soft-nitriding non-thermally refined crank shaft and its producing method | |
| US20090110589A1 (en) | Steel Material and Process for Producing the Same | |
| JP2021167444A (en) | Compression coil spring | |
| JP4818632B2 (en) | Shaft with excellent fatigue resistance and method for improving fatigue characteristics | |
| JP2006292108A (en) | Crank shaft and its manufacturing method | |
| WO2005100626A1 (en) | Crankshaft excellent in flexural fatigue strength | |
| KR101717390B1 (en) | Untempered soft-nitrided component | |
| JP4010023B2 (en) | Soft nitrided non-tempered crankshaft and manufacturing method thereof | |
| WO2006030800A1 (en) | High strength machine parts and shaft excellent in fatigue characteristics, and method for improving fatigue characteristics thereof | |
| JP2012020298A (en) | Method for manufacturing forging | |
| JP2002121645A (en) | Steel for gear having excellent dedendum bending fatigue characteristic and facial pressure fatigue characteristic and gear | |
| JP4403044B2 (en) | Crankshaft fatigue characteristics improvement method | |
| JP5916553B2 (en) | Steel for connecting rod and connecting rod |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A621 | Written request for application examination |
Free format text: JAPANESE INTERMEDIATE CODE: A621 Effective date: 20060907 |
|
| A977 | Report on retrieval |
Free format text: JAPANESE INTERMEDIATE CODE: A971007 Effective date: 20090326 |
|
| A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20090407 |
|
| A521 | Written amendment |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20090601 |
|
| TRDD | Decision of grant or rejection written | ||
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 Effective date: 20090901 |
|
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 |
|
| A61 | First payment of annual fees (during grant procedure) |
Free format text: JAPANESE INTERMEDIATE CODE: A61 Effective date: 20090907 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20120911 Year of fee payment: 3 |
|
| R151 | Written notification of patent or utility model registration |
Ref document number: 4374306 Country of ref document: JP Free format text: JAPANESE INTERMEDIATE CODE: R151 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20120911 Year of fee payment: 3 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20120911 Year of fee payment: 3 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20130911 Year of fee payment: 4 |
|
| S533 | Written request for registration of change of name |
Free format text: JAPANESE INTERMEDIATE CODE: R313533 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20130911 Year of fee payment: 4 |
|
| R350 | Written notification of registration of transfer |
Free format text: JAPANESE INTERMEDIATE CODE: R350 |
|
| S533 | Written request for registration of change of name |
Free format text: JAPANESE INTERMEDIATE CODE: R313533 |
|
| R350 | Written notification of registration of transfer |
Free format text: JAPANESE INTERMEDIATE CODE: R350 |
|
| LAPS | Cancellation because of no payment of annual fees |