KR20010058901A - Manufacturing methods for cam shaft made of spheroidal graphite cast iron based on Mo-B - Google Patents

Manufacturing methods for cam shaft made of spheroidal graphite cast iron based on Mo-B Download PDF

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KR20010058901A
KR20010058901A KR1019990066277A KR19990066277A KR20010058901A KR 20010058901 A KR20010058901 A KR 20010058901A KR 1019990066277 A KR1019990066277 A KR 1019990066277A KR 19990066277 A KR19990066277 A KR 19990066277A KR 20010058901 A KR20010058901 A KR 20010058901A
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South Korea
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cam shaft
cast iron
graphite cast
spheroidal graphite
manufacturing
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KR1019990066277A
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Korean (ko)
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고영상
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이계안
현대자동차주식회사
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Priority to KR1019990066277A priority Critical patent/KR20010058901A/en
Publication of KR20010058901A publication Critical patent/KR20010058901A/en

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    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/30—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for crankshafts; for camshafts
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/26—Methods of annealing
    • C21D1/32—Soft annealing, e.g. spheroidising
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D11/00—Process control or regulation for heat treatments
    • C21D11/005—Process control or regulation for heat treatments for cooling
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D5/00—Heat treatments of cast-iron
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C37/00—Cast-iron alloys
    • C22C37/04—Cast-iron alloys containing spheroidal graphite

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Heat Treatment Of Articles (AREA)

Abstract

PURPOSE: A method for manufacturing cam shaft of Mo-B based spheroidal graphite cast iron is provided to improve workability more than 300%, abrasion resistance, and durability by improving cooling temperature condition. CONSTITUTION: In a method for manufacturing a cam shaft of Mo-B based spheroidal graphite cast iron including the steps of melting alloy in an electric furnace, inoculating Mg into a ladle, inputting mold, soft annealing, the soft annealing is conducted at 730°C for 70-140 minutes, and the cam shaft cast product is cooled to 450-350°C at a cooling rate of 4-7°C/minute.

Description

Ｍｏ-Ｂ계 구상흑연주철 캠 샤프트 제조방법{Manufacturing methods for cam shaft made of spheroidal graphite cast iron based on Mo-B}Manufacturing method for cam shaft made of spheroidal graphite cast iron based on Mo-B}

본 발명은 자동차 부품용 캠 샤프트의 제조방법에 관한 것으로서, 더욱 상세하게는 자동차용 엔진부품으로 사용되는 Mo-B계 구상흑연주철 캠 샤프트의 내마모성을 증대시키기 위하여 주조공정에서 연화소둔 열처리 공정시 냉각 온도조건을 새롭게 개선함으로써 가공성과 물성을 크게 향상시킨 내마모성이 우수한 Mo-B계 구상 흑연 주철 캠 샤프트를 제조하는 방법에 관한 것이다.The present invention relates to a method for manufacturing a cam shaft for an automotive part, and more particularly, to increase the wear resistance of a Mo-B-based nodular cast iron camshaft used as an engine part for an automobile. The present invention relates to a method for producing a Mo-B-based spheroidal graphite cast iron camshaft excellent in abrasion resistance which greatly improves workability and physical properties by newly improving temperature conditions.

자동차용 부품에서 주요 부품으로 사용되고 있는 캠 샤프트의 재질과 관련하여 종래의 캠-샤프트 소재로는 일반적인 구상흑연주철이 사용되었으나, 이 재질은 내마모성이 떨어져 Mo-B계 카바이드를 생성시키므로 내마모성이 우수한 Mo-B계 소재가 캠 샤프트의 재료로 사용되어 왔다.In spite of the camshaft material used as the main part in automobile parts, the general spherical graphite cast iron is used as the cam-shaft material. However, since the material has low abrasion resistance, it generates Mo-B-based carbide. The B-based material has been used as the material of the camshaft.

이와 같이, 캠 사프트의 재질로 Mo-B계 구상흑연 주철을 사용하는 경우, 주조공정시 래들에서 Mo, B 등의 합금 원소를 첨가하여 용해하는데, 이때 사용되는 방법으로는 래들에서 합금을 용해한 후 래들에 접종하거나, 전기로 합금을 용해한후 래들에 접종하거나, 또는 전기로 합금을 용해한 후 성형면에 접종하는 방법을 사용하였다.As described above, in the case of using Mo-B-based spheroidal graphite cast iron as the material of the cam shaft, alloy elements such as Mo and B are added to the ladle during the casting process, and in this case, the alloy is dissolved in the ladle. A method of inoculating the ladle, inoculating the ladle after dissolving the alloy with electricity, or inoculating the molding surface after dissolving the alloy with electricity was used.

특히 이러한 주조공정이 완료된 후에는 잔존 압축응력을 제거하고 조직을 연화시키기 위해서 연화소둔 열처리를 하는데, 이때 연화소둔 열처리 조건은 730℃에서 1시간 유지한 다음 냉각 속도를 제어하지 않고, 150℃ 오일 배쓰 분위기에서 냉각시키는 방법으로 시행되었으며, 이 경우의 냉각 속도는 10℃/분 이상으로 유지되었다.In particular, after the casting process is completed, the soft annealing heat treatment is performed to remove the residual compressive stress and soften the tissue. At this time, the soft annealing heat treatment condition is maintained at 730 ° C. for 1 hour and then the cooling rate is not controlled. It was carried out by cooling in the atmosphere, in which case the cooling rate was maintained at 10 ℃ / min or more.

그러나, 상기와 같은 종래의 캠 샤프트 제조를 위한 주조 공정 및 열처리 공정은 드릴링시 2 ∼ 3 개/1회로 매우 저조한 가공성을 나타내며, 래들에서의 합금용해 및 연화소둔 열처리 후 퍼얼라이트가 분해되어 유리 페라이트와 유리 세멘타이트 과량으로 생성할 뿐만 아니라 압축 잔류 응력잔존과 래들합금 용해로 인한 조대한 탄화물의 생성으로 가공성이 매우 불량하며 공구의 마모가 극심한 문제점이 있었다.However, the casting process and heat treatment process for manufacturing a conventional cam shaft as described above shows very poor workability when drilling 2-3 times per drilling, and the ferrite decomposes after alloy melting and soft annealing heat treatment in the ladle, resulting in glass ferrite. In addition to the excessive generation of and free cementite, as well as the formation of coarse carbides due to residual compressive residual stress and ladle alloy dissolution, the workability is very poor and the wear of the tool is severe.

또한, 캠 샤프트는 부품 특성상 강한 물성과 내마모성이 요구되는 것이므로 그 재질의 완성된 금속조직이 퍼얼라이트 조직, 구상화 흑연 및 세멘타이트 조직으로 이루어진 조성이 되어야 하는데, 종래의 방법에 의한 캠 샤프트의 금속 조직은 퍼얼라이트 조직, 구상화 흑연에 유리 세멘타이트, 유리 페라이트 및 베이나이크 조직이 생성되어 그 금속조직이 매우 불량하여 각종 물성과 내마모성이 저하되는 문제가 있었다.In addition, since the camshaft is required to have strong physical properties and abrasion resistance due to the characteristics of the parts, the finished metal structure of the material should be composed of a pearlite structure, a spheroidized graphite and cementite structure, the metal structure of the cam shaft by the conventional method There was a problem in that glass cementite, glass ferrite, and bainike structure were formed in the silver pearlite structure and the spheroidized graphite, and the metal structure was very poor, resulting in deterioration of various physical properties and wear resistance.

상기한 바와 같은 종래의 문제점을 개선하기 위해서는 무엇보다도 주조 후 열처리에 의한 연화공정에서의 공정조건이 매우 중요할 것이라는 판단 하에 오랜 연구 끝에 캠 샤프트의 제조 공정에서 특정용해공정을 선택함과 아울러서 금속조직의 특성을 개선하기 위해 연화소둔 열처리 공정의 조건을 개선하면 보다 우수한 물성의 주조제품을 얻을 수 있다는 사실을 알게 되어 본 발명을 완성하게 되었다.In order to improve the above-mentioned problems, above all, the process conditions in the softening process by heat treatment after casting are very important. When the conditions of the soft annealing heat treatment process were improved to improve the properties of the present invention, it was found that a cast product having excellent physical properties was obtained, thereby completing the present invention.

따라서, 본 발명은 Mo-B계 구상 흑연 주철의 캠 샤프트 제조를 위한 주조 공정 중에 전기로 합금용해 공정을 사용하되, 주조 후의 연화소둔 열처리 공정에서 냉각속도를 제어함으로써, 캠 샤프트의 내마모성을 향상시킨 자동차 부품용 캠 샤프트의 새로운 제조 방법을 제공하는 데 그 목적이 있다.Therefore, the present invention uses an alloy melting process during the casting process for producing a cam shaft of Mo-B spherical graphite cast iron, but by controlling the cooling rate in the soft annealing heat treatment process after casting, to improve the wear resistance of the cam shaft The object is to provide a new method of manufacturing a camshaft for an automotive part.

본 발명은 Mo-B계 구상 흑연 주철을 이용하여 전기로 합금용해, 래들접종 및 몰드 투입과정을 거치되, 주조 연화과정에서 730℃에서 일정 시간 유지 후 냉각시키는 연화소둔 열처리를 시행하여 자동차 부품용 캠 샤프트를 제조하는 방법에 있어서, 상기 연화 소둔 열처리를 730℃에서 1시간 10분 ∼ 1시간 50분 유지시킨 후 냉각 속도를 4 ∼ 7℃/분으로 하여 550 ∼ 350℃까지 냉각시킨 다음 방냉시켜 캠 샤프트를 제조하는 것을 그 특징으로 한다.The present invention is a molten annealing, ladle inoculation and mold injection process using the Mo-B-based spheroidal graphite cast iron, while in the casting softening process is subjected to soft annealing heat treatment for cooling after maintaining a certain time at 730 ℃ for automotive parts In the method for producing a cam shaft, the soft annealing heat treatment is maintained at 730 ℃ for 1 hour 10 minutes to 1 hour 50 minutes, and then cooled to 550 ~ 350 ℃ at 4 ~ 7 ℃ / min cooling rate and then allowed to cool It is characterized by manufacturing a cam shaft.

이와 같은 본 발명을 더욱 상세히 설명하면 다음과 같다.Referring to the present invention in more detail as follows.

본 발명에서는 Mo-B계 구상 흑연 주철을 이용하여 자동차 부품용 캠 샤프트를 제조함에 있어서 종래 사용하였던 여러 공법 중에서 전기로 합금용해 후 래들 접종(Mg주입)을 한 다음, 몰드 투입하여 완성하는 공법으로 제조한다. 이와 같이, 본 발명에서는 고온 용해로 인해 흑연 및 탄화물이 균일하고, 미세 석출에 유리하며, 특히 합금 성분의 균질 확산으로 인하여 미세하고 균일한 주조 금속조직을 얻기 위하여 전기로 합금용해 공정에 의한 제조 공법을 선택하여 캠 샤프트를 제조한다.In the present invention, in the manufacture of cam shafts for automobile parts using Mo-B-based spheroidal graphite cast iron, after ladle inoculation (Mg injection) after alloy melting by electric furnace among the various methods used in the past, Manufacture. As such, in the present invention, graphite and carbides are uniform due to high temperature melting, and are advantageous for fine precipitation, and in particular, a manufacturing method by an electrolytic alloy melting process is used to obtain a fine and uniform cast metal structure due to homogeneous diffusion of alloying components. Select to manufacture the camshaft.

본 발명은 특히 캠 샤프트 주조 제품의 연화소둔 열처리 공정에서 종래에 냉각조건에 대한 제어 없이 냉각시키므로서 금속조직의 치밀성과 불균일한 조직의 형성이 있었던 점을 개선하기 위해 730℃에서 약 1시간 유지 후 냉각시킬 때 상기 연화온도에서의 유지시간을 종래보다 다소 긴 1시간 10분 ∼ 1시간 50분, 더욱 바람직하기로는 1시간 30분 내외 동안 유지시킨 후 냉각시키며, 특히 냉각 속도를 4 ∼ 8℃/분, 더욱 바람직하기로는 5 ∼ 6℃/분 내외의 속도로 냉각되도록 제어하고, 이렇게 냉각속도를 제어하는 조건으로 계속 냉각상태를 유지하면서 450 ∼ 350℃, 더욱 바람직하기로는 400℃ 전후의 온도까지 냉각시킨 다음에는 인위적 냉각제어를 멈추고 그대로 방냉시켜서 연화처리를 완성한다.In the present invention, in particular, in the soft annealing heat treatment process of a camshaft cast product, after cooling for about 1 hour at 730 ° C. to improve the density of metal structures and the formation of non-uniform structures, the cooling is performed without control of cooling conditions. When cooling, the holding time at the softening temperature is maintained for 1 hour 10 minutes to 1 hour 50 minutes, more preferably 1 hour and 30 minutes, which is somewhat longer than before, and then cooled, and the cooling rate is 4-8 ° C. / Minutes, more preferably controlled to cool at a rate of about 5 to 6 ℃ / minute, and while maintaining the cooling state under the conditions that control the cooling rate to 450 to 350 ℃, more preferably to a temperature around 400 ℃ After cooling, the artificial cooling control is stopped and allowed to cool as it is to complete the softening treatment.

본 발명에서는 냉각속도의 제어가 제조된 금속조직의 물성에 영향을 주는 매우 중요한 인자가 되는 바, 본 발명에서 냉각 속도를 제어하는 이유는 730℃에서 냉각 초기시 조금만 빨리 냉각되어도, CCT 곡선상의 퍼얼라이트 존을 지나치지 않게 되어 유리 페라이트, 유리 세멘타이트, 베이라이트, 등의 조직이 생성되어 가공성이 불량해지기 때문이다. 즉, 상기와 같이 냉각 속도를 조절하면, 구상화 흑연, 퍼얼라이트, 세멘타이트 조직으로 이루어진 매우 양호한 조직의 Mo-B계 캠 샤프트를 얻을 수 있다.In the present invention, the control of the cooling rate is a very important factor affecting the physical properties of the produced metal structure. The reason for controlling the cooling rate in the present invention is that even if the cooling is only a little faster at the initial stage of cooling at 730 ° C, This is because a structure such as glass ferrite, glass cementite, bayite, or the like is formed by not passing the light zone, resulting in poor workability. That is, by adjusting the cooling rate as described above, a very good Mo-B type camshaft composed of spherical graphite, pearlite and cementite structure can be obtained.

만일, 연화 온도에서의 유지 시간이 너무 짧으면 연화가 충분하지 않게 되는 경우가 있으므로 바람직하기로는 종래의 1시간 보다 긴 유지상태가 필요하며, 냉각속도를 너무 급작스럽게 하거나 조절하지 않는 경우등 본 발명의 조건을 벗어나면 금속 조직상의 불균일 특성이 초래되어 물성이나 내마모성이 저하되는 문제가 있고, 방냉 이전의 냉각속도 제어를 너무 저온까지 유지하거나 너무 고온에서 중단하면 역시 금속조직이 불량하여 물성에 좋지 못한 영향을 주게 된다.If the holding time at the softening temperature is too short, softening may not be sufficient. Preferably, a holding state longer than the conventional 1 hour is required, and the cooling rate is too sudden or not adjusted. If the condition is out of condition, there is a problem that the property of the metal structure is inferior due to the non-uniform characteristic, and the property of the metal or the wear resistance is deteriorated. Will be given.

위와 같이, 본 발명에 따라 제조된 캠 샤프트는 내마모성 등 그 물성이 종래에 비하여 매우 우수하고, 가공성도 종래보다 약 300%이상 증가하는 효과를 나타낸다.As described above, the camshaft manufactured according to the present invention has excellent physical properties such as abrasion resistance compared to the conventional, and exhibits an effect of increasing workability by about 300% or more.

이와 같은 본 발명을 실시예에 의거하여 더욱 상세히 설명하겠는 바, 본 발명이 실시예에 의해 한정되는 것은 아니다.Although this invention is demonstrated in more detail based on an Example, this invention is not limited by an Example.

실시예 및 비교예Examples and Comparative Examples

통상의 캠 샤프트 제조방법으로 제조하되 다음 표 1과 같은 조건으로 캠 샤프트를 제조하였으며, 그 물성 측정 결과는 다음 표 2에 나타내었다.The camshaft was manufactured by the conventional camshaft manufacturing method, but the camshaft was manufactured under the conditions shown in Table 1 below, and the results of the measurement of the physical properties are shown in Table 2 below.

자동차용 엔진부품으로 사용되는 Mo-B계 구상 흑연 주철 캠 샤프트의 내마모성을 증대시키기 위하여 주조공정에서 연화소둔 열처리 공정시 냉각 온도조건을 새롭게 개선함으로써 가공성을 약 300%이상 향상시키고, 내마모성이 우수하여 내구성이 크게 향상되었으며, 오일 베쓰를 사용하지 않으므로 환경오염방지 효과도 있다.In order to increase the abrasion resistance of Mo-B spherical graphite cast iron camshaft used for automobile engine parts, the cooling temperature condition is newly improved during the soft annealing heat treatment process in the casting process, which improves the workability by about 300%. Durability is greatly improved, and since it does not use oil bath, it also prevents environmental pollution.

Claims (1)

Mo-B계 구상 흑연 주철을 이용하여 전기로 합금용해, 래들접종 및 몰드 투입과정을 거치되, 주조 연화과정에서 730℃에서 일정 시간 유지 후 냉각시키는 연화소둔 열처리를 시행하여 자동차 부품용 캠 샤프트를 제조하는 방법에 있어서, 상기 연화 소둔 열처리를 730℃에서 1시간 10분 ∼ 1시간 50분 유지시킨 후 냉각 속도를 4 ∼ 7℃/분으로 하여 450 ∼ 350℃까지 냉각시킨 다음 방냉시켜 캠 샤프트를 제조하는 것을 특징으로 하는 자동차 부품용 캠 샤프트를 제조하는 방법.Cam-shaft for automobile parts is subjected to soft annealing heat treatment by molten alloy heating, ladle inoculation and mold injection process using Mo-B-based spheroidal graphite cast iron. In the manufacturing method, the soft annealing heat treatment is maintained at 730 ℃ for 1 hour 10 minutes to 1 hour 50 minutes and then cooled to 450 ~ 350 ℃ at 4 ~ 7 ℃ / min cooling rate and then cooled to cam shaft A method of manufacturing a cam shaft for an automotive part, characterized in that for producing.
KR1019990066277A 1999-12-30 1999-12-30 Manufacturing methods for cam shaft made of spheroidal graphite cast iron based on Mo-B KR20010058901A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2023249954A3 (en) * 2022-06-20 2024-02-08 Cummins Inc. Systems and methods for improving iron-based camshaft fatigue life

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS61133361A (en) * 1984-11-30 1986-06-20 Ngk Insulators Ltd Spheroidal graphite cast iron and its manufacture
JPS62192527A (en) * 1986-02-19 1987-08-24 Hitachi Metals Ltd Heat treatment of spheroidal graphite cast iron
JPH0472014A (en) * 1990-07-09 1992-03-06 Hitachi Metals Ltd Method for continuously casting spheroidal graphite cast iron bar
KR920012497A (en) * 1990-12-28 1992-07-27 이경훈 Manufacturing method of connecting rod of spheroidized graphite cast iron
KR19980076417A (en) * 1997-04-07 1998-11-16 이광래 Cast Iron Alloy and Manufacturing Method of High Toughness Cast Iron and Ostamper Nodular Graphite Iron

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS61133361A (en) * 1984-11-30 1986-06-20 Ngk Insulators Ltd Spheroidal graphite cast iron and its manufacture
JPS62192527A (en) * 1986-02-19 1987-08-24 Hitachi Metals Ltd Heat treatment of spheroidal graphite cast iron
JPH0472014A (en) * 1990-07-09 1992-03-06 Hitachi Metals Ltd Method for continuously casting spheroidal graphite cast iron bar
KR920012497A (en) * 1990-12-28 1992-07-27 이경훈 Manufacturing method of connecting rod of spheroidized graphite cast iron
KR19980076417A (en) * 1997-04-07 1998-11-16 이광래 Cast Iron Alloy and Manufacturing Method of High Toughness Cast Iron and Ostamper Nodular Graphite Iron

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2023249954A3 (en) * 2022-06-20 2024-02-08 Cummins Inc. Systems and methods for improving iron-based camshaft fatigue life

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