JP2007284769A - Method for manufacturing connecting rod, and connecting rod - Google Patents
Method for manufacturing connecting rod, and connecting rod Download PDFInfo
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- JP2007284769A JP2007284769A JP2006115797A JP2006115797A JP2007284769A JP 2007284769 A JP2007284769 A JP 2007284769A JP 2006115797 A JP2006115797 A JP 2006115797A JP 2006115797 A JP2006115797 A JP 2006115797A JP 2007284769 A JP2007284769 A JP 2007284769A
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Abstract
Description
本発明は、コネクティングロッドの製造方法およびコネクティングロッドに関し、さらに詳しくは、粉体材料から圧粉体を成形する圧粉体成形工程と、該圧粉体を燒結して燒結体とする焼結工程と、該焼結体を熱間鍛造する熱間鍛造工程と、を行うことにより、クランク軸が連結される大端部と、ピストンピンが連結される小端部と、大端部と小端部の間に延在するコラム部と、を有するコネクティングロッドを製造する方法、および、粉体材料から成形された圧粉体を燒結し、その後熱間鍛造して、クランク軸が連結される大端部と、ピストンピンが連結される小端部と、大端部と小端部の間に延在するコラム部と、が形成されてなるコネクティングロッドに関するものである。
なお、以下の説明においては、コネクティングロッドを場合によってコンロッドと略称する。
The present invention relates to a method of manufacturing a connecting rod and a connecting rod, and more specifically, a green compact forming step of forming a green compact from a powder material, and a sintering step of sintering the green compact to form a sintered body. And a hot forging step for hot forging the sintered body, a large end to which the crankshaft is connected, a small end to which the piston pin is connected, a large end and a small end And a method of manufacturing a connecting rod having a column portion extending between the portions, and compacting a green compact formed from a powder material, followed by hot forging to connect the crankshaft. The present invention relates to a connecting rod in which an end portion, a small end portion to which a piston pin is connected, and a column portion extending between the large end portion and the small end portion are formed.
In the following description, the connecting rod is abbreviated as a connecting rod in some cases.
内燃機関のピストンとクランクシャフトを連結するコンロッドは、クランク軸が連結される大端部と、ピストンピンが連結される小端部と、大端部と小端部を連結するコラム部と、が形成されている。このようなコンロッドでは、一般に、特にコラム部は、ピストンの往復運動とクランクシャフトの回転による慣性力により衝撃的な引張および圧縮荷重や曲げ荷重などを繰返し受けるため、これらの荷重に対する強度、特に耐疲労強度が要求される。一方、コンロッドの大端部と小端部は、クランクシャフトとピストンピンがそれぞれ摺動可能に連結されるため、成形後に軸受メタルを設けるなどの目的で切削や研削などの機械加工が施されるため、被削性が容易であることが要求される。すなわち、コンロッドのコラム部と大端部および小端部とでは、相反する特性が求められる。 A connecting rod that connects a piston and a crankshaft of an internal combustion engine has a large end portion to which a crankshaft is connected, a small end portion to which a piston pin is connected, and a column portion that connects the large end portion and the small end portion. Is formed. In such connecting rods, in particular, the column portion, in particular, is repeatedly subjected to shocking tensile and compressive loads, bending loads, etc. by the inertial force due to the reciprocating motion of the piston and the rotation of the crankshaft. Fatigue strength is required. On the other hand, since the crankshaft and the piston pin are slidably connected to the large end and the small end of the connecting rod, machining such as cutting and grinding is performed for the purpose of providing a bearing metal after molding. Therefore, it is required that machinability is easy. That is, contradictory characteristics are required at the column portion of the connecting rod, the large end portion, and the small end portion.
このようなコンロッドには、焼結により作られた焼結コンロッドが従来から知られている（例えば、特許文献１）。また、別の従来のコンロッドには、各種荷重に対する強度を高めるために、浸炭してコンロッドの表面層の炭素量を高めるなど、コンロッドに表面硬化処理を施すことにより硬化させたものが知られている（例えば、特許文献２）。 As such a connecting rod, a sintered connecting rod made by sintering has been conventionally known (for example, Patent Document 1). Another conventional connecting rod is known to be hardened by subjecting the connecting rod to surface hardening, such as carburizing to increase the carbon content of the surface layer of the connecting rod in order to increase the strength against various loads. (For example, Patent Document 2).
上記特許文献１は、コストアップを招くことなく、強度が高く、且つ軽量で、且つ低振動であるようなコンロッドを提供することを目的としたもので、鉄系の焼結材料を燒結することによって作られたコンロッドであって、コンロッド全体の平均密度は６．８〜７．４ｇ／ｃｍ3の範囲にあり、クランクシャフトと接する大端部については密度が他の部分よりも小さく（低く）６．５〜７．２ｇ／ｃｍ3の範囲にあることを特徴とする焼結コンロッドが開示されている。特許文献１のコンロッドは、焼結だけによって作られているので、全体が高強度であり且つ軽く、また、大端部の密度を他の部分よりも小さくしたので低振動であることが記載されている（公報第２頁右上欄第３行〜同欄第１４行）。
また、特許文献１には、高強度と軽量性と低振動とをある程度のレベルで兼ね備えている従来のコンロッドとして、焼結と熱間鍛造との両方を実施するものや、焼結とショットピーニングと冷間コイニングとを組み合わせたものが挙げられている（公報第１頁右下欄第５行〜同欄第１４行）。
The above-mentioned Patent Document 1 aims to provide a connecting rod that is high in strength, light in weight, and low in vibration without causing an increase in cost, and sintering an iron-based sintered material. The average density of the whole connecting rod is in the range of 6.8 to 7.4 g / cm 3 , and the density at the large end contacting the crankshaft is smaller (lower) than the other parts. A sintered connecting rod is disclosed which is characterized by being in the range of 6.5 to 7.2 g / cm 3 . Since the connecting rod of Patent Document 1 is made only by sintering, it is described that it is high in strength and light as a whole, and has low vibration because the density of the large end portion is smaller than other portions. (Gazette page 2, upper right column, line 3 to column 14, line 14).
Patent Document 1 discloses a conventional connecting rod that combines high strength, light weight, and low vibration at a certain level, and performs both sintering and hot forging, and sintering and shot peening. And cold coining are listed (the first page, lower right column, line 5 to line 14).
一方、上記特許文献２は、大端部や小端部の表面強度をより向上させることができると共に、連結棒部（コラム部）の靱性を確保できるコンロッドを提供することを課題としたもので、クランク軸が連結される大端部と、ピストンが連結される小端部と、これら大端部及び小端部の間を連結する連結棒部とを有するコンロッドにおいて、前記大端部と小端部は複数回表面硬化処理を実施し、前記連結棒部は前記大端部と小端部の表面硬化処理回数よりも少ない回数表面硬化処理を行うか、又は、表面硬化処理をしないことを特徴とする表面硬化処理したコンロッドが開示されている。
すなわち、特許文献２では、小端部及び大端部の表面を硬化させて耐磨耗性や強度を向上しさらに耐疲労強度を向上させ、連結棒部については、耐磨耗性を必要としないので、小端部及び大端部ほどには表面を硬くする必要が無く、衝撃的な引張りあるいは圧縮荷重に耐えるように、小端部及び大端部の表面より積極的に表面硬さを低下させるものである。
そして、特許文献２では、部分的に表面硬化処理の回数を制御するために、表面硬化処理回数の少ない連結棒部を銅メッキ等によりマスキングすることが記載されている（００１７などを参照）。
On the other hand, Patent Document 2 is intended to provide a connecting rod that can further improve the surface strength of the large end portion and the small end portion and can secure the toughness of the connecting rod portion (column portion). A connecting rod having a large end connected to the crankshaft, a small end connected to the piston, and a connecting rod connecting the large end and the small end; The end portion is subjected to surface hardening treatment a plurality of times, and the connecting rod portion is subjected to surface hardening treatment less than the number of surface hardening treatments of the large end portion and the small end portion, or is not subjected to surface hardening treatment. A featured hardened connecting rod is disclosed.
That is, in patent document 2, the surface of a small end part and a large end part is hardened, and wear resistance and intensity | strength are improved, and also fatigue resistance strength is improved, About a connection rod part, abrasion resistance is required. Therefore, it is not necessary to harden the surface as much as the small end and large end, and the surface hardness is more positive than the surface of the small end and large end so as to withstand shocking tensile or compressive loads. It is to reduce.
And in patent document 2, in order to control the frequency | count of a surface hardening process partially, masking the connecting rod part with few surface hardening processes frequency by copper plating etc. is described (refer 0017 etc.).
しかしながら、上述したように、コンロッドの特に大端部と小端部の間に延在するコラム部は、各種荷重に対する強度が要求され、また、コンロッドの大端部と小端部は、機械加工を施すために被削性が求められる。
これに対して、上記特許文献１にあっては、焼結のみによって作られているため、全体の強度をより向上させることが困難であるという問題があった。そして、上記特許文献１に開示されたコンロッドの強度を向上させるため、特許文献１の焼結によって作られたコンロッドに、さらに上記特許文献２に開示されているような浸炭などの表面硬化処理を行うことが考えられるが、この場合には、特許文献１に開示されているコンロッドの大端部の密度が比較的小さい（開気孔率が高い）大端部のほうが表面積が多いために表面硬化処理がされ易くその表面層の硬度が高くなり、また、密度が比較的大きい（開気孔率が低い）コラム部と小端部は、表面積が少ないために表面硬化処理がされ難いことから、その表面層の硬度を高めることができず、大端部に要求される被削性やコラム部に要求される強度を満たすことができないという問題が発生することとなる。
また、上記特許文献２にあっても、小端部及び大端部の表面を硬化させるものであるためにかかる部位の被削性が悪く、また、連結棒部の表面硬化処理回数が少ないことからかかる部位の表面硬さが低く強度が不足するという問題があった。さらに、特許文献２にあっては、部位によって表面硬化処理の回数を異ならせるために、マスキングをする必要があり、手間やコストがかかるなどの問題があった。
However, as described above, the column portion extending between the large end portion and the small end portion of the connecting rod is required to have strength against various loads, and the large end portion and the small end portion of the connecting rod are machined. Therefore, machinability is required.
On the other hand, in the above-mentioned Patent Document 1, since it is made only by sintering, there is a problem that it is difficult to further improve the overall strength. And in order to improve the intensity | strength of the connecting rod disclosed by the said patent document 1, surface hardening processes, such as carburizing as disclosed by the said patent document 2, are further applied to the connecting rod made by sintering of the patent document 1. In this case, since the density of the large end of the connecting rod disclosed in Patent Document 1 is relatively small (the open porosity is high), the large end has a larger surface area. Since the surface layer is hard to be treated and the hardness of the surface layer is high, and the column portion and the small end portion having a relatively large density (low open porosity) are difficult to be hardened due to their small surface area. The hardness of the surface layer cannot be increased, and there arises a problem that the machinability required for the large end portion and the strength required for the column portion cannot be satisfied.
Moreover, even in the above-mentioned Patent Document 2, since the surface of the small end portion and the large end portion is hardened, the machinability of such a part is poor, and the number of surface hardening treatments of the connecting rod portion is small. Therefore, there is a problem that the surface hardness of such a portion is low and the strength is insufficient. Furthermore, in Patent Document 2, in order to vary the number of times of surface hardening treatment depending on the part, it is necessary to perform masking, and there is a problem that it takes time and cost.
本発明は、上述した問題に鑑みてなされたもので、簡単な構成で、被削性が要求される大端部と小端部を硬化させることなく、強度が要求されるコラム部を容易に硬化させることができるコネクティングロッドの製造方法およびコネクティングロッドを提供することを目的とする。 The present invention has been made in view of the above-described problems. With a simple configuration, the column portion that requires strength can be easily formed without hardening the large end portion and the small end portion that require machinability. It is an object of the present invention to provide a method of manufacturing a connecting rod that can be cured and a connecting rod.
請求項１のコネクティングロッドの製造方法に係る発明は、上記目的を達成するため、粉体材料から圧粉体を成形する圧粉体成形工程と、該圧粉体を燒結して燒結体とする焼結工程と、該焼結体を熱間鍛造する熱間鍛造工程と、を行うことにより、クランク軸が連結される大端部と、ピストンピンが連結される小端部と、大端部と小端部の間に延在するコラム部と、を有するコネクティングロッドを製造する方法であって、前記圧粉体成形工程で、圧粉体の前記コラム部となる部分の密度を前記大端部と前記小端部となる部分の密度よりも低く成形し、前記焼結工程で圧粉体を表面硬化処理することを特徴とする。なお、圧粉体は、大端部と小端部となる部分の密度を７．１ｇ／ｃｍ3以上とすると共に、コラム部となる部分の密度を６．２〜６．８ｇ／ｃｍ3に成形することが望ましい。
請求項２のコネクティングロッドに係る発明は、上記目的を達成するため、粉体材料から成形された圧粉体を燒結し、その後熱間鍛造して、クランク軸が連結される大端部と、ピストンピンが連結される小端部と、大端部と小端部の間に延在するコラム部と、が形成されてなるコネクティングロッドであって、前記焼結体の段階で、前記コラム部となる部分の開気孔率が前記大端部と前記小端部となる部分の開気孔率よりも高くなっており、かつ、表面硬化処理されていることを特徴とする。なお、焼結体の段階では、コラム部となる部分の開気孔率が３０％、より好ましくは５０％以上で、大端部と小端部となる部分の開気孔率が１０％以下であることが望ましい。
In order to achieve the above object, the invention according to the manufacturing method of the connecting rod of claim 1 is a green compact forming step of forming a green compact from a powder material, and the green compact is sintered to form a sintered body. By performing a sintering step and a hot forging step for hot forging the sintered body, a large end to which the crankshaft is connected, a small end to which the piston pin is connected, and a large end And a column portion extending between the small end portion, and a connecting rod having a column portion extending between the small end portion, wherein the density of the portion that becomes the column portion of the green compact is increased in the green compact forming step. The green compact is shaped to be lower than the density of the portion and the small end portion, and the green compact is subjected to surface hardening treatment in the sintering step. In the green compact, the density of the portion serving as the large end portion and the small end portion is set to 7.1 g / cm 3 or more, and the density of the portion serving as the column portion is set to 6.2 to 6.8 g / cm 3 . It is desirable to mold.
In order to achieve the above-mentioned object, the connecting rod of claim 2 is a method of sintering a green compact formed from a powder material, then hot forging, and a large end to which a crankshaft is connected, A connecting rod having a small end to which a piston pin is connected and a column extending between the large end and the small end, wherein the column is formed at the stage of the sintered body. The open porosity of the portion to be is higher than the open porosity of the portion to be the large end portion and the small end portion, and is subjected to surface hardening treatment. In the sintered body stage, the open porosity of the portion to be the column portion is 30%, more preferably 50% or more, and the open porosity of the portion to be the large end portion and the small end portion is 10% or less. It is desirable.
請求項１の発明では、圧粉体成形工程で、圧粉体のコラム部となる部分の密度を大端部と小端部となる部分の密度よりも低く成形することにより、焼結体のコラム部となる部分の開気孔率が大端部と小端部となる部分の開気孔率よりも高くなる、すなわち、焼結体のコラム部となる部分の表面積が大端部と小端部となる部分の表面積よりも多くなる。そのため、焼結工程で表面硬化処理することにより、コラム部となる部分がその内部まで充分に表面硬化処理されて硬度が上昇し、また、大端部と小端部はコラム部と比較して硬度が上昇し難い。したがって、コラム部が要求される強度を備えると共に、大端部と小端部が要求される被削性を備えたコネクティングロッドが製造される。
請求項２の発明では、焼結体の段階で、コラム部となる部分の開気孔率が大端部と前記小端部となる部分の開気孔率よりも高くなっており、かつ、表面硬化処理されていることにより、コラム部となる部分がその内部まで充分に表面硬化処理されて硬度が上昇しており、また、大端部と小端部はコラム部と比較して硬度が低く抑えられている。したがって、コネクティングロッドは、コラム部が要求される強度を備えると共に、大端部と小端部が要求される被削性を備えている。
In the first aspect of the invention, in the green compact forming step, the density of the portion to be the column portion of the green compact is formed to be lower than the density of the portions to be the large end portion and the small end portion. The open porosity of the portion that becomes the column portion is higher than the open porosity of the portion that becomes the large end portion and the small end portion, that is, the surface area of the portion that becomes the column portion of the sintered body is large end portion and small end portion More than the surface area of the part. Therefore, by surface hardening treatment in the sintering process, the part that becomes the column part is sufficiently surface hardened to the inside to increase the hardness, and the large end part and the small end part are compared with the column part. Hardness does not rise easily. Accordingly, a connecting rod having the strength required for the column portion and the machinability required for the large end portion and the small end portion is manufactured.
In the invention of claim 2, the open porosity of the portion that becomes the column portion is higher than the open porosity of the portion that becomes the large end portion and the small end portion at the stage of the sintered body, and surface hardening is performed. Due to the treatment, the part that becomes the column part is sufficiently hardened to the inside and the hardness is increased, and the hardness at the large end part and the small end part is kept lower than the column part. It has been. Therefore, the connecting rod has the strength required for the column portion and the machinability required for the large end portion and the small end portion.
請求項１の発明によれば、粉体成形工程で、圧粉体のコラム部となる部分の密度を大端部と小端部となる部分の密度よりも低く成形し、焼結工程で圧粉体を表面硬化処理する、という簡単な構成で、被削性が要求される大端部と小端部を硬化させることなく、強度が要求されるコラム部を容易に硬化させることが可能なコネクティングロッドの製造方法を提供することができる。
請求項２の発明によれば、焼結体の段階で、コラム部となる部分の開気孔率が大端部と小端部となる部分の開気孔率よりも高くなっており、かつ、表面硬化処理されている、という簡単な構成で、被削性を要求される大端部と小端部が硬化することなく、強度を要求されるコラム部が容易に且つ確実に硬化したコネクティングロッドを提供することができる。
According to the invention of claim 1, in the powder forming step, the density of the portion that becomes the column portion of the green compact is formed lower than the density of the portion that becomes the large end portion and the small end portion, and the pressure is reduced in the sintering step. With a simple configuration of surface-treating the powder, it is possible to easily harden the column parts that require strength without hardening the large and small ends that require machinability. A method of manufacturing a connecting rod can be provided.
According to the invention of claim 2, at the stage of the sintered body, the open porosity of the portion to be the column portion is higher than the open porosity of the portion to be the large end portion and the small end portion, and the surface With a simple structure that is hardened, the connecting rod is hardened easily and reliably in the column part that requires strength without hardening the large end part and small end part that require machinability. Can be provided.
最初に、本発明のコンロッドの製造方法の実施の一形態を、図１〜図４に基づいて詳細に説明する。図において、同一符号は同様の部分または相当する部分に付すものとする。
本発明のコンロッドの製造方法は、概略、粉体材料から圧粉体１を成形する圧粉体成形工程と、この圧粉体１を燒結して燒結体１’とする焼結工程と、この焼結体１’を熱間鍛造する熱間鍛造工程と、を行うことにより、クランク軸が連結される大端部１０”と、ピストンピンが連結される小端部１１”と、大端部１０”と小端部１１”の間に延在するコラム部１２”と、を有するコネクティングロッド１”を製造するもので、圧粉体成形工程で、圧粉体１のコラム部１２”となる部分１２の密度を、大端部１０”と小端部１１”となる部分１０、１１の密度よりも低く成形し、その後の焼結工程で圧粉体１を表面硬化処理するものである。
First, an embodiment of a method for manufacturing a connecting rod according to the present invention will be described in detail with reference to FIGS. In the drawings, the same reference numerals are given to similar or corresponding parts.
The connecting rod manufacturing method of the present invention generally includes a green compact forming step of forming a green compact 1 from a powder material, a sintering step of sintering the green compact 1 to form a sintered body 1 ', A hot forging step of hot forging the sintered body 1 ', a large end 10 "to which the crankshaft is connected, a small end 11" to which the piston pin is connected, and a large end A connecting rod 1 ″ having a column portion 12 ″ extending between 10 ″ and a small end portion 11 ″ is manufactured, and becomes a column portion 12 ″ of the green compact 1 in the green compact forming process. The density of the portion 12 is formed to be lower than the density of the portions 10 and 11 that become the large end portion 10 ″ and the small end portion 11 ″, and the green compact 1 is subjected to surface hardening treatment in the subsequent sintering process.
最初に、本発明により製造されるコンロッド１”の形状を図３に基づいて説明する。コンロッド１”は、端部に大端部１０”と小端部１１”とが形成されており、大端部１０”と小端部１１”の間にはコラム部１２”が延在している。この実施の形態においては、大端部１０”と小端部１１”には、クランクピンとピストンピンを受けるための大端孔１０ａ”と小端孔１１ａ”がそれぞれ形成されている。大端部１０”は、図に示した実施の形態に限定されることなく、キャップ部と分割して構成し、このキャップ部をボルトにより締結するものであってもよい。 First, the shape of the connecting rod 1 ″ manufactured according to the present invention will be described with reference to FIG. 3. The connecting rod 1 ″ has a large end portion 10 ″ and a small end portion 11 ″ formed at the ends, and is thus large. A column portion 12 ″ extends between the end portion 10 ″ and the small end portion 11 ″. In this embodiment, the large end portion 10 ″ and the small end portion 11 ″ have a crank pin and a piston pin. A large end hole 10a "and a small end hole 11a" are respectively formed. The large end part 10 "is not limited to the embodiment shown in the figure, and is divided from the cap part. And this cap part may be fastened with a volt | bolt.
コンロッド１”を製造するにあたり、最初に、粉体材料として所定の粉末原料を予め混粉したプレミックス粉を準備し、成形型のキャビティ内に供給して、製造するコンロッド１”の形状に応じて図１に示すような圧粉体１を成形する（圧粉体成形工程）。このとき、成形型のキャビティのコラム部１２”となる部分１２を成形するための部分には、大端部１０”と小端部１１”となる部分１０、１１を成形するための部分よりも少ない量の粉体材料が充填される。これにより、圧粉体１のコラム部１２”となる部分１２の密度は、大端部１０”と小端部１１”となる部分１０、１１の密度よりも低く、すなわち、コラム部１２”となる部分１２が大端部１０”と小端部１１”となる部分１０、１１よりも疎の状態で成形されることとなる。この実施の形態では、例えば、大端部１０”および小端部１１”となる部分の密度が７．１ｇ／ｃｍ3以上で、また、コラム部１２”となる部分１２の密度が６．２〜６．８ｇ／ｃｍ3の範囲で成形される。 In manufacturing the connecting rod 1 ″, first, a premix powder prepared by mixing a predetermined powder raw material in advance as a powder material is prepared and supplied into the cavity of the molding die, depending on the shape of the connecting rod 1 ″ to be manufactured. Then, a green compact 1 as shown in FIG. 1 is formed (green compact forming step). At this time, the portion for forming the column portion 12 ″ of the mold cavity 12 is formed more than the portion for forming the portions 10 and 11 to be the large end portion 10 ″ and the small end portion 11 ″. A small amount of the powder material is filled. Thereby, the density of the portion 12 which becomes the column portion 12 ″ of the green compact 1 is the density of the portions 10 and 11 which become the large end portion 10 ″ and the small end portion 11 ″. Lower, that is, the portion 12 that becomes the column portion 12 ″ is formed in a sparser state than the portions 10 and 11 that become the large end portion 10 ″ and the small end portion 11 ″. For example, the density of the portion that becomes the large end portion 10 ″ and the small end portion 11 ″ is 7.1 g / cm 3 or more, and the density of the portion 12 that becomes the column portion 12 ″ is 6.2 to 6.8 g / Molded in the range of cm 3 .
次いで、図２に示すように、圧粉体１を焼結炉などで燒結して焼結体１’とする（焼結工程）。このとき、焼結炉内は、たとえばＣＯ２量が０．０６％以下、より好ましくは０．０４％以下に制御されたＲＸガスなどの浸炭性ガス雰囲気とされている。また、圧粉体１は、たとえば、図４に示すように、常温から１０００℃までを２００℃／min以上の昇温速度で（第１昇温ゾーン）、１０００℃以上を３０℃／minの昇温速度で（第２昇温ゾーン）加熱され、約１１５０℃に所定時間保持される（均熱ゾーン）。そのため、圧粉体１は、燒結されて焼結体１’となるときに、同時に表面硬化処理として浸炭される。このとき、焼結体１’は、たとえば０．６〜０．８％のカーボンポテンシャルでパーライトとなる。圧粉体１の大端部１０”と小端部１１”となる部分１０、１１の密度が高くなるように成形されていることから、焼結体１’のかかる部分１０’、１１’の開気孔率が低くなる。一方、圧粉体１のコラム部１２”となる部分１２の密度が低くなるように成形されていることから、焼結体１’のかかる部分１２’の開気孔率が高くなる。たとえば、この実施の形態では、焼結体１’の大端部１０”と小端部１１”となる部分１０’、１１’の開気孔率を１０％以下で、コラム部１２”となる部分１２’の開気孔率を３０％以上、さらに好ましくは５０％以上に確保する。 Next, as shown in FIG. 2, the green compact 1 is sintered in a sintering furnace or the like to obtain a sintered body 1 '(sintering step). At this time, the inside of the sintering furnace is a carburizing gas atmosphere such as RX gas in which the amount of CO 2 is controlled to 0.06% or less, more preferably 0.04% or less. In addition, as shown in FIG. 4, the green compact 1 has a temperature increase rate of 200 ° C./min or higher from normal temperature to 1000 ° C. (first temperature increase zone), and a temperature of 1000 ° C. or higher of 30 ° C./min. Heated at a rate of temperature rise (second temperature rise zone) and held at about 1150 ° C. for a predetermined time (soaking zone). Therefore, when the green compact 1 is sintered into the sintered body 1 ′, it is simultaneously carburized as a surface hardening treatment. At this time, the sintered body 1 ′ becomes pearlite with a carbon potential of 0.6 to 0.8%, for example. Since the density of the portions 10 and 11 that become the large end portion 10 ″ and the small end portion 11 ″ of the green compact 1 is increased, the portions 10 ′ and 11 ′ of the sintered body 1 ′ Open porosity is lowered. On the other hand, since the density of the portion 12 which becomes the column portion 12 ″ of the green compact 1 is reduced, the open porosity of the portion 12 ′ of the sintered body 1 ′ is increased. In the embodiment, the open porosity of the portions 10 ′ and 11 ′ that become the large end portion 10 ″ and the small end portion 11 ″ of the sintered body 1 ′ is 10% or less, and the portion 12 ′ that becomes the column portion 12 ″. The open porosity is secured to 30% or more, more preferably 50% or more.
ここで、開気孔率について説明する。開気孔率は次の数式（１）によって求められる。 Here, the open porosity will be described. The open porosity is obtained by the following formula (1).
上述したように、圧粉体１の大端部１０”と小端部１１”となる部分１０、１１は、その密度が高くなるように成形されているため、浸炭性ガスが内部に侵入しにくく、従ってかかる部分１０、１１における内部での浸炭反応が生じにくく表面だけにとどまることから大端部１０”と小端部１１”において硬化する度合が少なく、後の機械加工工程での被削性を損なうことがない。一方、圧粉体１のコラム部１２”となる部分１２は、密度が低くなるように成形されているため、焼結と同時に浸炭性ガスが開放気孔から内部に容易に侵入し、従ってかかる部分１２における浸炭反応が内部でも生じることから硬化が促進され、コラム部１２”の耐疲労強度などが強化されることとなる。すなわち、本発明では、焼結と同時に浸炭するのであるが、積極的に硬化させたい部分であるコラム部１２”と、硬化を抑えたい部分である大端部１０”および小端部１１”とで、部分的に、圧粉体１の密度を異ならせることにより、焼結体１’の開気孔率を部分的に異ならせ、その結果、浸炭による硬化の度合を部分的に異ならせている。 As described above, the portions 10 and 11 which become the large end portion 10 ″ and the small end portion 11 ″ of the green compact 1 are formed so as to have a high density, so that the carburizing gas enters the inside. Therefore, the carburizing reaction inside the portions 10 and 11 is difficult to occur, and only the surface remains. Therefore, the degree of hardening at the large end portion 10 ″ and the small end portion 11 ″ is small, and the machining in the subsequent machining process is performed. There is no loss of sex. On the other hand, since the portion 12 which becomes the column portion 12 ″ of the green compact 1 is formed so as to have a low density, the carburizing gas easily penetrates into the inside from the open pores simultaneously with the sintering, and accordingly, this portion. Since the carburization reaction in 12 occurs also inside, hardening is accelerated and the fatigue strength of the column portion 12 ″ and the like are strengthened. That is, in the present invention, the carburizing is performed simultaneously with the sintering, but the column portion 12 ″ that is a portion that is to be hardened positively, and the large end portion 10 ″ and the small end portion 11 ″ that are portions that are desired to suppress hardening. Thus, by partially varying the density of the green compact 1, the open porosity of the sintered body 1 ′ is partially varied, and as a result, the degree of hardening by carburization is partially varied. .
焼結工程で焼結されると共に浸炭されて得られた焼結体１’は、直ちに鍛造型で鍛造される。このとき、焼結体１’は、鍛造型によって圧縮され、気孔が潰される。そして、鍛造工程が終了すると、大気中で常温となるまで放冷する。コンロッド１”は、焼結により昇温された状態からそのまま熱間鍛造されて放冷されるために焼ならしされて、大端部１０”と小端部１１”の被削性を低下させることなく、また、特にコラム部１２”の強度が向上する。 The sintered body 1 ′ obtained by sintering and carburizing in the sintering process is immediately forged with a forging die. At this time, the sintered body 1 ′ is compressed by the forging die and the pores are crushed. And when a forge process is complete | finished, it cools until it will become normal temperature in air | atmosphere. The connecting rod 1 ″ is hot forged from the state heated by sintering as it is and is allowed to cool, so that it is normalized to reduce the machinability of the large end portion 10 ″ and the small end portion 11 ″. In addition, the strength of the column portion 12 ″ is particularly improved.
本発明の実施例を図５および図６を含めて以下に説明する。この実施例では、粉末材料として、鉄粉に２％の銅粉と０．５％の黒鉛粉末を混合したプレミックス粉を用意した。そして、圧粉体成形工程では、圧粉体１の密度分布を、大端部１０”となる部分１０を７．１３ｇ／ｃｍ3、また、小端部１１”となる部分１１を７．１８ｇ／ｃｍ3となるように成形すると共に、コラム部１２”となる部分１２を６．４０ｇ／ｃｍ3となるように成形した。 An embodiment of the present invention will be described below including FIG. 5 and FIG. In this example, a premix powder prepared by mixing iron powder with 2% copper powder and 0.5% graphite powder was prepared as a powder material. In the green compact forming step, the density distribution of the green compact 1 is 7.13 g / cm 3 for the portion 10 that becomes the large end portion 10 ″ and 7.18 g for the portion 11 that becomes the small end portion 11 ″. / cm 3 and thereby molded into a was molded portion 12 serving as the column portion 12 "so that the 6.40 g / cm 3.
次いで、焼結工程では、ＣＯ２が０．０５％のＲＸガス雰囲気の焼結炉で、図４に参照されるように、脱ワックス工程を兼ねて、常温の状態から第１昇温ゾーンで２１０℃／minで、続いて、第２昇温ゾーンで３１℃／minで１１５０℃となるまで昇温させてから、この温度で１５分間保持して（均熱ゾーン）、焼結体１’を得た。このときの焼結体１’の開気孔率は、大端部１０”となる部分１０’が７％、小端部１１”となる部分１１’が６％、コラム部１２”となる部分１２’が４６％であった。 Next, in the sintering step, as shown in FIG. 4, in a sintering furnace having an RX gas atmosphere of 0.05% CO 2, the dewaxing step is also performed, and the normal temperature is increased from 210 to 210 in the first heating zone. Subsequently, the temperature was raised to 1150 ° C. at 31 ° C./min in the second temperature raising zone, and then held at this temperature for 15 minutes (soaking zone) to obtain the sintered body 1 ′. Obtained. The open porosity of the sintered body 1 ′ at this time is 7% for the portion 10 ′ that becomes the large end portion 10 ″, 6% for the portion 11 ′ that becomes the small end portion 11 ″, and the portion 12 that becomes the column portion 12 ″. 'Was 46%.
１１５０℃に保持して得た焼結体１’を焼結炉から取り出し、速やかに鍛造型にセットして、約４９０Ｍｐａ（ton/cm2）の圧力で鍛造を行い（熱間鍛造工程）、気孔を潰して、大気中放冷して常温となるまで冷却してコンロッド１”を得た。 The sintered body 1 ′ obtained by maintaining at 1150 ° C. is taken out from the sintering furnace, quickly set in a forging die, and forged at a pressure of about 490 Mpa (ton / cm 2 ) (hot forging process) The pores were crushed, allowed to cool in the air, and cooled to room temperature to obtain a connecting rod 1 ″.
このようにして製造された本発明のコンロッド１”の硬さを測定すると共に引張試験を行った。その結果は、ヴィッカース硬さで大端部１０”がＨＶ（９８Ｎ）２６７、小端部１１”がＨＶ２７１、コラム部１２”がＨＶ３３５となり、大端部１０”および小端部１１”と比較してコラム部１２”が硬くなっていた。また、引張強さは、９８ｋｇ／ｍｍ2（コラム部１２”で破断）であった。そして、図５に電子顕微鏡写真で示すように、本発明により製造されたコンロッドのコラム部における組織は、白く見えるフェライトと黒く見えるセメンタイトが層状となったパーライトラメラーとなっていることが明確に確認できることから、強度が向上しているものと判断できる。 The connecting rod 1 ″ of the present invention thus manufactured was measured for hardness and subjected to a tensile test. As a result, the large end portion 10 ″ was HV (98N) 267 and the small end portion 11 was Vickers hardness. "HV271 and column portion 12" became HV335, and the column portion 12 "was harder than the large end portion 10" and the small end portion 11 ". The tensile strength was 98 kg / mm 2 (column Part 12 ″). Then, as shown in the electron micrograph in FIG. 5, it is clearly confirmed that the structure of the column portion of the connecting rod manufactured according to the present invention is a pearlite lamellar layered with white-looking ferrite and black-looking cementite. From this, it can be determined that the strength is improved.
本発明によるコンロッド１”と比較するための例を以下に示す。この比較例では、粉末材料として、上述した本発明による実施例と同様に鉄粉に２％の銅粉と０．５％の黒鉛粉末を混合したプレミックス粉を準備したが、圧粉体成形工程では、圧粉体（１）の密度分布を、大端部（１０”）となる部分（１０）を７．１１ｇ／ｃｍ3、小端部（１１”）となる部分（１１）を７．１４ｇ／ｃｍ3、、コラム部（１２”）となる部分（１２）を７．１５ｇ／ｃｍ3となるように成形した。そして、上述した本発明による実施例と同様に、焼結工程で表面硬化処理として浸炭し、直ちに熱間鍛造した後に大気中で放冷した。比較例の焼結体（１’）の開気孔率は、大端部（１０”）となる部分（１０’）と小端部（１１”）となる部分（１１’）が共に７％で、コラム部（１２”）となる部分（１２’）が６％であった。 An example for comparison with the connecting rod 1 "according to the present invention is shown below. In this comparative example, as a powder material, as in the above-described embodiment according to the present invention, 2% copper powder and 0.5% of iron powder are used. A premix powder in which graphite powder was mixed was prepared. In the green compact forming step, the density distribution of the green compact (1) was determined to be 7.11 g / cm at the portion (10) that becomes the large end (10 ″). 3, were molded portion to be a small end (11 ") and a portion of (11) 7.14 g / cm 3 ,, column section (12 ') (12) so that 7.15 g / cm 3. And like the Example by this invention mentioned above, it carburized as a surface hardening process by a sintering process, Then, after carrying out hot forging immediately, it stood to cool in air | atmosphere. The open porosity of the sintered body (1 ′) of the comparative example is 7% for both the portion (10 ′) that becomes the large end portion (10 ″) and the portion (11 ′) that becomes the small end portion (11 ″). The portion (12 ′) to be the column portion (12 ″) was 6%.
このようにして製造された比較例のコンロッド（１”）の硬さを本発明の実施例によるコンロッド１”と同様に測定すると共に引張試験を行った。その結果は、ヴィッカース硬さで大端部（１０”）がＨＶ（９８Ｎ）２６０、小端部（１１”）がＨＶ２５５、コラム部（１２”）がＨＶ２６５となり、大端部（１０”）および小端部（１１”）とコラム部（１２”）とがほぼ同じ程度で硬化していた。また、引張強さは、７６ｋｇ／ｍｍ2（コラム部（１２”）で破断）であった。そして、図６に電子顕微鏡写真で示すように、比較例のコンロッド（１”）のコラム部（１２”）における組織は、白く見えるフェライトが多く、黒く見えるセメンタイトと層状をなすパーライトラメラーとなっていないことが明確に確認できることから、本発明による実施例よりも強度が向上していない。 The hardness of the connecting rod (1 ″) of the comparative example manufactured as described above was measured in the same manner as the connecting rod 1 ″ according to the example of the present invention, and a tensile test was performed. The result is that the Vickers hardness is HV (98N) 260 at the large end (10 ″), HV255 at the small end (11 ″), HV265 at the column end (12 ″), and the large end (10 ″) and The small end portion (11 ″) and the column portion (12 ″) were cured to approximately the same degree. The tensile strength was 76 kg / mm 2 (breaking at the column part (12 ″)). As shown in the electron micrograph in FIG. 6, the column part (1 ″) of the comparative example ( The structure in 12 ″) has many ferrites that appear white, and since it can be clearly confirmed that it is not a pearlite lamellar layered with cementite that appears black, the strength is not improved as compared with the examples according to the present invention.
本発明によるコンロッド１”は、焼結体１’の段階で、コラム部１２”となる部分１２’の開気孔率が大端部１０”と小端部１１”となる部分１０’、１１’の開気孔率よりも高くなっており、かつ、浸炭処理されているため、コラム部１２”となる部分１２’の開放気孔から内部にまで浸炭性ガスが侵入して充分硬化されており、また、大端部１０”と小端部１１”となる部分１０’、１１’ではその表面だけが浸炭性ガスによって硬化されている。そのため、コラム部１２”の強度が向上しており、また、大端部１０”と小端部１１”の被削性が低下してはいない。 The connecting rod 1 ″ according to the present invention has a portion 10 ′, 11 ′ in which the open porosity of the portion 12 ′ that becomes the column portion 12 ″ becomes the large end portion 10 ″ and the small end portion 11 ″ at the stage of the sintered body 1 ′. Since the carburizing treatment is performed, the carburizing gas penetrates from the open pores of the portion 12 ′ to become the column portion 12 ″ into the inside, and is sufficiently cured. In the portions 10 ′ and 11 ′ that become the large end portion 10 ″ and the small end portion 11 ″, only the surfaces thereof are hardened by the carburizing gas. Therefore, the strength of the column portion 12 ″ is improved, The machinability of the large end portion 10 ″ and the small end portion 11 ″ is not deteriorated.
１：圧粉体、 １’：焼結体、 １”：コンロッド、 １０：圧粉体の大端部となる部分、 １１：圧粉体の小端部となる部分、 １２：圧粉体のコラム部となる部分、 １０’：焼結体の大端部となる部分、 １１’ ：焼結体の小端部となる部分、 １２’：焼結体のコラム部となる部分、 １０”：コンロッドの大端部、 １１” ：コンロッドの小端部、 １２”：コンロッドのコラム部、
1: green compact, 1 ′: sintered body, 1 ″: connecting rod, 10: part to be the large end of the green compact, 11: part to be the small end of the green compact, 12: green compact 10 ′: a part that becomes the large end of the sintered body, 11 ′: a part that becomes the small end of the sintered body, 12 ′: a part that becomes the column part of the sintered body, 10 ″: Large end of connecting rod, 11 ": Small end of connecting rod, 12": Column of connecting rod,
Claims (2)
前記圧粉体成形工程で、圧粉体の前記コラム部となる部分の密度を前記大端部と前記小端部となる部分の密度よりも低く成形し、
前記焼結工程で圧粉体を表面硬化処理することを特徴とするコネクティングロッドの製造方法。 A green compact forming process for forming a green compact from a powder material, a sintering process for sintering the green compact into a sintered body, and a hot forging process for hot forging the sintered compact. By doing so, a connecting rod having a large end connected to the crankshaft, a small end connected to the piston pin, and a column extending between the large end and the small end is manufactured. A method,
In the green compact forming step, the density of the portion that becomes the column portion of the green compact is formed lower than the density of the portion that becomes the large end portion and the small end portion,
A method of manufacturing a connecting rod, wherein the green compact is subjected to a surface hardening treatment in the sintering step.
前記焼結体の段階で、前記コラム部となる部分の開気孔率が前記大端部と前記小端部となる部分の開気孔率よりも高くなっており、かつ、表面硬化処理されていることを特徴とするコネクティングロッド。
A green compact formed from a powder material is sintered, and then hot forged, then a large end to which the crankshaft is connected, a small end to which the piston pin is connected, a large end and a small end A connecting rod formed between, and a column portion extending between
At the stage of the sintered body, the open porosity of the portion that becomes the column portion is higher than the open porosity of the portion that becomes the large end portion and the small end portion, and is subjected to surface hardening treatment. Connecting rod characterized by that.
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| JP2006115797A JP2007284769A (en) | 2006-04-19 | 2006-04-19 | Method for manufacturing connecting rod, and connecting rod |
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| JP2006115797A JP2007284769A (en) | 2006-04-19 | 2006-04-19 | Method for manufacturing connecting rod, and connecting rod |
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| JP2007284769A true JP2007284769A (en) | 2007-11-01 |
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| EP2231353A2 (en) * | 2008-01-04 | 2010-09-29 | Gkn Sinter Metals, Llc | Prealloyed copper powder forged connecting rod |
| JP2011508091A (en) * | 2007-12-27 | 2011-03-10 | ホガナス アクチボラグ （パブル） | Low alloy steel powder |
| JP2011508090A (en) * | 2007-12-27 | 2011-03-10 | ホガナス アクチボラグ （パブル） | Low alloy steel powder |
| CN103921086A (en) * | 2014-05-12 | 2014-07-16 | 临沂市金立机械有限公司 | Method for forging connecting rod of small gasoline engine |
| CN105750556A (en) * | 2015-01-06 | 2016-07-13 | 现代自动车株式会社 | Green Compact Of Sintered Connecting Rod Using Different Kinds Of Powder And Method Of Manufacturing The Same |
| CN106670375A (en) * | 2016-11-28 | 2017-05-17 | 重庆万斯金属特种成形有限公司 | Forging method for gasoline engine connecting rod |
| WO2017170913A1 (en) * | 2016-03-30 | 2017-10-05 | Ntn株式会社 | Connecting rod, connecting rod module, and method for manufacturing same |
| DE112017001636T5 (en) | 2016-03-30 | 2018-12-13 | Ntn Corporation | Connecting rod, connecting rod module and method for its production |
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| JP2015108195A (en) * | 2007-12-27 | 2015-06-11 | ホガナス アクチボラグ （パブル） | Low alloy steel powder |
| JP2011508091A (en) * | 2007-12-27 | 2011-03-10 | ホガナス アクチボラグ （パブル） | Low alloy steel powder |
| JP2011508090A (en) * | 2007-12-27 | 2011-03-10 | ホガナス アクチボラグ （パブル） | Low alloy steel powder |
| JP2015110842A (en) * | 2007-12-27 | 2015-06-18 | ホガナス アクチボラグ （パブル） | Low alloy steel powder |
| US8935852B2 (en) | 2008-01-04 | 2015-01-20 | Gkn Sinter Metals, Llc | Prealloyed copper powder forged connecting rod |
| EP2231353A2 (en) * | 2008-01-04 | 2010-09-29 | Gkn Sinter Metals, Llc | Prealloyed copper powder forged connecting rod |
| EP2231353A4 (en) * | 2008-01-04 | 2013-10-16 | Gkn Sinter Metals Llc | Prealloyed copper powder forged connecting rod |
| JP2011509348A (en) * | 2008-01-04 | 2011-03-24 | ジーケーエヌ シンター メタルズ、エル・エル・シー | Pre-alloyed copper alloy powder forged connecting rod |
| CN103921086A (en) * | 2014-05-12 | 2014-07-16 | 临沂市金立机械有限公司 | Method for forging connecting rod of small gasoline engine |
| CN105750556A (en) * | 2015-01-06 | 2016-07-13 | 现代自动车株式会社 | Green Compact Of Sintered Connecting Rod Using Different Kinds Of Powder And Method Of Manufacturing The Same |
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| WO2017170913A1 (en) * | 2016-03-30 | 2017-10-05 | Ntn株式会社 | Connecting rod, connecting rod module, and method for manufacturing same |
| DE112017001636T5 (en) | 2016-03-30 | 2018-12-13 | Ntn Corporation | Connecting rod, connecting rod module and method for its production |
| CN106670375A (en) * | 2016-11-28 | 2017-05-17 | 重庆万斯金属特种成形有限公司 | Forging method for gasoline engine connecting rod |
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