JP2564489B2 - Rocker arm with high strength, high toughness and wear resistance - Google Patents

Description

TECHNICAL FIELD The present invention relates to a rocker arm for an internal combustion engine, which has high strength and high toughness and is excellent in wear resistance.

[Conventional technology]

Conventionally, in general, for manufacturing rocker arms of an internal combustion engine,
Many wear resistant Fe-based casting alloys are used.

[Problems to be solved by the invention]

However, with the recent increase in engine output and weight reduction,
Rocker arms are also required to be smaller and thinner, but conventional wear-resistant Fe-based cast alloy rocker arms all show excellent wear resistance, but lack strength and toughness. Due to the reason, it is the current situation that these requirements cannot be satisfied sufficiently.

[Means for solving problems]

Therefore, the present inventors, from the above viewpoints, as a result of research to develop a Fe-based cast alloy rocker arm having high strength and high toughness, and also excellent in wear resistance, % (Hereinafter% indicates% by weight), C: 2 to 4%, Cr: 15.5 to 25%, Mo: 1 to 10%, Si: 0.1 to 2%, Mn: 0.1 to 2%, Co: 0.1 〜1.9%, W: 0.1〜1.9%, Ni: 0.1〜3%, the balance is composed of Fe and unavoidable impurities, and the rocker arm made of Fe-based cast alloy has high strength and high toughness. In addition, it has been found that it is excellent in wear resistance, so that it can be made smaller and thinner, and that it exhibits excellent performance even in practical use under severe conditions.

The present invention has been made based on the above findings, and the reason why the component composition is limited as described above will be described below.

(A) CC The C component has a function of improving the strength by forming a solid solution in a part of the base material, forming carbides, improving wear resistance, and further improving castability. If the content is less than 2%, the desired effect cannot be obtained, while if the content exceeds 4%, the toughness of the alloy will decrease, so the content was defined as 2-4%. .

(B) Cr The Cr component has the function of forming carbides and significantly improving the wear resistance of the alloy, but if the content is less than 15.5%, the desired excellent wear resistance cannot be secured. On the other hand, when the content exceeds 25%, the toughness of the alloy is significantly deteriorated, so the content was defined as 15.5 to 25%.

(C) Mo Mo component forms carbides to improve wear resistance,
In addition, it has a function of improving the alloy strength by forming a solid solution in the base material, but if the content is less than 1%, the desired effect cannot be obtained, while if the content exceeds 10%, the above effect Since no further improvement effect was obtained, the content was set to 1 to 10% in consideration of economic efficiency.

(D) Si The Si component has not only a deoxidizing effect but also an effect of improving the castability, but if its content is less than 0.1%, the desired effect cannot be obtained on the other hand, while its content is 2%. When it exceeds%,
Since the toughness is reduced, its content is 0.1
It was set at ~ 2%.

(E) Mn The Mn component has a deoxidizing action as well as Si as well as an action to improve the toughness of the alloy. However, if the content is less than 0.1%, the desired action cannot be obtained. If the content exceeds 2%, the wear resistance will decrease, so the content was defined as 0.1 to 2%.

(F) Co The Co component has the function of forming a solid solution in the base material to improve the strength of the alloy, but if its content is less than 0.1%, the desired strength improving effect cannot be obtained, while its content is 1.9. Even if it exceeds%, no further improvement effect can be obtained. Considering economic efficiency,
Its content was set to 0.1-1.9%.

(G) The WW component has a strength-improving effect due to solid solution and a wear resistance-improving effect due to formation of carbide, but if the content is less than 0.1%, the desired effect cannot be obtained for the above-mentioned effect. If the content exceeds 1.9%, the toughness of the alloy will deteriorate, so the content was defined as 0.1 to 1.9%.

(H) Ni The Ni component has the action of forming a solid solution in the base material to further improve the toughness of the alloy, but if its content is less than 0.1%, the desired high toughness cannot be secured, while its content Is 3%
If it exceeds, the wear resistance will decrease,
Its content was set to 0.1 to 3%.

〔Example〕

Next, the Fe-based casting alloy of the present invention will be specifically described by way of examples.

Using an ordinary high-frequency melting furnace, Fe-based alloy melts each having the composition shown in Table 1 were prepared, and then these Fe-based alloy melts were cast into a loar calm by the usual lost wax method. In the atmosphere, after holding at a predetermined temperature in the range of 850 to 950 ° C for 1 hour, quenching of oil quenching, and in the atmosphere, to a predetermined temperature in the range of 550 to 620 ° C.
The present invention can be obtained by carrying out a tempering treatment of standing cooling after holding for 5 hours. Rocker arms 1-16 and comparative rocker arms 1-12
Were manufactured respectively.

Each of the comparative rocker arms 1 to 12 has a composition in which any one of the constituent components (marked with * in Table 1) is out of the range of the present invention.

Next, for various Fe-based casting alloy rocker arms obtained as a result, tensile strength for the purpose of evaluating strength,
The Charpy impact value was measured for the purpose of evaluating the toughness, and the Rockwell hardness (C scale) was measured for the purpose of evaluating the wear resistance, and this was incorporated into a 4-cylinder OHC engine. Engine speed: 850r. pm, oil: LPG waste oil (oil temperature: 60 ° C), material of cam as counterpart member: chill material of FC25, operating time: 200 hours, actual wear test was performed, rocker arm and cam maximum wear depth Was measured. The results of these measurements are shown in Table 1.

〔The invention's effect〕

From the results shown in Table 1, the rocker arm 1 of the present invention
Each of ~ 16 has high strength and high toughness, and shows excellent wear resistance in a state of low opponent attack, whereas as seen in Comparative Rocker Arms 1 to 12, It is clear that if the content of any one of the above is out of the range of the present invention, at least one of the above properties becomes inferior.

As described above, since the rocker arm of the present invention has high strength and high toughness, it is possible to reduce the size and thickness of the rocker arm, and it has low opponent attack and excellent wear resistance. It has industrially useful properties such as excellent performance over a remarkably long period of time.

Front page continuation (72) Kenichi Kitazono 2-4-1, Hamamatsucho, Minato-ku, Tokyo Inside Tokyo Branch of Mitsubishi Metal Co., Ltd. (56) References JP-A-59-23846 (JP, A) JP-A-59 -13046 (JP, A) JP 58-3950 (JP, A) JP 56-84442 (JP, A) JP 42-23706 (JP, B1)

Claims (1)

(57) [Claims] 1. C: 2 to 4%, Cr: 15.5 to 25%, Mo: 1 to 10%, Si: 0.1 to 2%, Mn: 0.1 to 2%, Co: 0.1 to 1.9%, W: 0.1 .About.1.9%, Ni: 0.1 to 3%, and the balance consisting of a Fe-based cast alloy having a composition (hereinafter, wt%) consisting of Fe and unavoidable impurities. High strength, high toughness and wear resistance. Rocker arm with.