EP0416418B1 - Method of making rocker arm - Google Patents

Method of making rocker arm Download PDF

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Publication number
EP0416418B1
EP0416418B1 EP19900116371 EP90116371A EP0416418B1 EP 0416418 B1 EP0416418 B1 EP 0416418B1 EP 19900116371 EP19900116371 EP 19900116371 EP 90116371 A EP90116371 A EP 90116371A EP 0416418 B1 EP0416418 B1 EP 0416418B1
Authority
EP
European Patent Office
Prior art keywords
weight
rocker arm
amount
added
cast iron
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 - Lifetime
Application number
EP19900116371
Other languages
German (de)
English (en)
French (fr)
Other versions
EP0416418A3 (en
EP0416418A2 (en
Inventor
Makoto C/O Nissan Motor Company Limited Kano
Ichiro C/O Nissan Motor Company Limited Tanimoto
Osamu C/O Nippon Piston Ring Co. Ltd. Kawamura
Teruo C/O Nippon Piston Ring Co. Ltd. Takahashi
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Nissan Motor Co Ltd
Nippon Piston Ring Co Ltd
Original Assignee
Nissan Motor Co Ltd
Nippon Piston Ring Co Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Nissan Motor Co Ltd, Nippon Piston Ring Co Ltd filed Critical Nissan Motor Co Ltd
Publication of EP0416418A2 publication Critical patent/EP0416418A2/en
Publication of EP0416418A3 publication Critical patent/EP0416418A3/en
Application granted granted Critical
Publication of EP0416418B1 publication Critical patent/EP0416418B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C33/00—Making ferrous alloys
    • C22C33/08—Making cast-iron alloys

Definitions

  • the present invention relates to a method of making a rocker arm utilizable as an element of a valve mechanism in an automotive internal combustion engine.
  • Anti-wear rocker arms as described in JP A Sho 63-303030, (& GB-A-2205108) are producible as one piece from high chrome cast iron by casting.
  • the anti-wear property is resulted from high-hardness carbides such as (Fe, Cr) 7 C 3 in the matrix.
  • Patent Abstracts of Japan, JP-A 53-1122 (1978) relates to high carbon, high chromium cast iron, wherein cast iron consisting of 3.2 % C, 0.2 - 1.5 % Si, 0.2 - 1.5 % Mn, 15 - 20 % Cr, 1.0 - 3.0 % V, further containing 0.3 - 3.0 % Mo and 0.3 - 3.0 % Ni is melted and the resulting molten metal is inoculated with 0,6 % Ca-Si.
  • DE-OS 27 38 379 is directed to a method for refining molten iron and steel bath, by adding a composite clad material, containing a core of e.g. calcium base alloys with a sheath of iron, into the molten iron and steel bath.
  • a composite clad material containing a core of e.g. calcium base alloys with a sheath of iron
  • High-hardness Fe-Cr-composite carbides tend to form a directional solidification in which acicular precipitates direct to the casting surface.
  • the acicular carbides abrase the sliding surface of the associated cam member.
  • acicular carbides can be rounded or globulized when tungsten is added in an amount of more than 10% by weight to the high chrome cast iron.
  • it can not be a solution of the problem, because the addition of more than 10% of tungsten is costly, what is worse, produces tungsten carbides that are highly hard and abrasive to the cam member.
  • the invention as claimed is intended to solve the problem as described above and has an object to provide a method of manufacturing a rocker arm that is less abrasive to the cam member associated. This problem is solved by the method defined in the claim.
  • the invention is achieved as a result of extensive research made from a finding that an addition agent for treating molten high chrome cast iron is effective to globulize Fe-Cr-composite carbides.
  • a Ca-Si base addition agent is added in an amount of 0.3 to 0.6% by weight to a molten metal in a process of casting a rocker arm as one piece from high chrome cast iron.
  • the Ca-Si base addition agent contains about 30% of Ca, about 60% of Si, and about 10% of impurities.
  • One or more of Sr, Zr, and Ce is added in an amount of 05 to 5% by weight to the agent.
  • the high chrome cast iron comprises by weight, of C: 2.5-3.7%, Si: 1.0-2.0%, Mn: 0.5-1.0%, Cr: 15-20%, Ni: 0.3-0.7%, P: no more than 0.3%, S: no more than 1.0%, and Fe and unavoidable impurities: the balance.
  • the cast iron may additionally contain one or more of W, Mo, Nb, Ta, Ti, and B in an amount of 3 to 10%, by weight, if necessary.
  • the Ca-Si base addition agent When the Ca-Si base addition agent is added to the molten metal not as a deoxidizer but as a globulizer, it is added in an amount of no less than 0.3% by weight.
  • the amount of less than 0.3% of the agent is insufficient to round carbide precipitates or achieve the object of the present invention.
  • the amount of more than 0.6% increase cost without more improvement of the roundness. Therefore, the addition agent is to the molten metal in an amount of 0.3 to 0.6% by weight.
  • the Ca-Si base addition agent is moderate in reaction, operable with ease, and contributable to a high yield.
  • the inventive method of casting a rocker arm as one piece from high chrome cast iron is characterized in that a Ca-Si base addition agent is added to the molten metal in an amount of 0.3 to 0.6% by weight.
  • the Ca-Si base addition agent is effective not only to deoxidize the molten metal but also to globulize precipitates of Fe-Cr carbide.
  • the method of the invention can produce a rocker arm of the type having globular precipitates of Fe-Cr carbide. This results to advantages that the rocker arm is the same in abrasion resistance as the conventional but less aggressive against the other member and that the cam member is less worn when coupled with the inventive rocker arm than when coupled with the conventional one.
  • the molten metal of each sample was treated with the individual agent of which the content, amount and elements added are given in Table 1. Every sample was hardened and tempered in the same way after casting. The samples were classified to 7 Examples and 2 Comparisons on the basis of the composition of the addition agent. Examples and Comparisons except Examples 1, 4, 5 and 7 were etched and photomicrographed as illustrated in FIGS. 1 to 5. The photomicrographs show white carbide grains distributed in the black pearlitic matrix. Each photomicrograph was analyzed by an image analyzer by which both the real and circumcircular areas of each carbide grain were measured for calculation of the ratio of the former to the latter. The average value of the ratios indicates the roundness or globularity of each of Examples and Comparisons. The values of globularity are also given in Table 1.
  • FIGS. 1 to 3 Examples have carbides in the shape of globular grains.
  • FIGS. 4 and 5 show that Comparisons have carbides in the shape of sharp or acicular grains. This difference in shape of carbides is also understood from the values of globularity in Table 1. Examples have the globularities of more than 42% while Comparisons have the globularities of 28% and 32%. It is known that, when the rocker arm has the globularity of more than 40%, it is unaggressive against the associated cam member with the result that the cam member is improved in weariness.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Valve-Gear Or Valve Arrangements (AREA)
  • Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
EP19900116371 1989-09-08 1990-08-27 Method of making rocker arm Expired - Lifetime EP0416418B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP1231732A JP2914634B2 (ja) 1989-09-08 1989-09-08 ロッカーアームの製造方法
JP231732/89 1989-09-08

Publications (3)

Publication Number Publication Date
EP0416418A2 EP0416418A2 (en) 1991-03-13
EP0416418A3 EP0416418A3 (en) 1992-06-10
EP0416418B1 true EP0416418B1 (en) 1996-11-06

Family

ID=16928167

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19900116371 Expired - Lifetime EP0416418B1 (en) 1989-09-08 1990-08-27 Method of making rocker arm

Country Status (3)

Country Link
EP (1) EP0416418B1 (ja)
JP (1) JP2914634B2 (ja)
DE (1) DE69029074T2 (ja)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104087813B (zh) * 2014-06-19 2016-01-27 宁国市正兴耐磨材料有限公司 一种矿山特种专用研磨球
CN109723513A (zh) * 2017-10-30 2019-05-07 丹阳市金长汽车部件有限公司 一种发动机气门摇臂
CN108220760B (zh) * 2017-12-29 2021-05-14 中钢集团邢台机械轧辊有限公司 一种含Nb的高铬铁轧辊
CN112695242B (zh) * 2020-11-30 2023-05-05 中钢集团邢台机械轧辊有限公司 一种开坯辊及其制备方法

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2045414C3 (de) * 1970-09-15 1975-06-05 Koerver & Nehring Gmbh, 4150 Krefeld Verwendung eines austenitischen Gußeisens mit Lamellengraphi für Gleitlager etc
JPS5129493B2 (ja) * 1971-12-24 1976-08-26
JPS5911656B2 (ja) * 1976-06-24 1984-03-16 川崎重工業株式会社 高硬度耐摩耗鋳鉄
US4094666A (en) * 1977-05-24 1978-06-13 Metal Research Corporation Method for refining molten iron and steels
DD254217A1 (de) * 1982-08-02 1988-02-17 Juergen Jahn Verfahren zur herstellung von hochverschleissfesten, schlagbeanspruchbaren gussteilen
JPS63303030A (ja) * 1987-05-30 1988-12-09 Nippon Piston Ring Co Ltd ロツカア−ム
JP2657402B2 (ja) * 1987-09-08 1997-09-24 本田技研工業株式会社 摺動部材を組合わせた摺動構造

Also Published As

Publication number Publication date
EP0416418A3 (en) 1992-06-10
EP0416418A2 (en) 1991-03-13
JP2914634B2 (ja) 1999-07-05
DE69029074D1 (de) 1996-12-12
JPH0397828A (ja) 1991-04-23
DE69029074T2 (de) 1997-04-03

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