JPS60208455A - Member for movable valve of internal-combustion engine - Google Patents

Abstract

PURPOSE:To obtain a member for movable valve of an internal-combustion engine having superior wear and scuffing resistances by adding graphite powder to a mixture of various kinds of metallic oxide powders to reduce the metallic oxide powders, mixing the reduced powders with FeP or FeB powder, and molding and sintering the mixture. CONSTITUTION:Metallic oxide powders are mixed so as to prepare a mixed alloy powder having a composition consisting of, by weight, one or more among 1-4% C, 10-40% Mo, 3-20% Cr, 1-10% Co, 0.005-0.8% P and 0.03-0.3% B, and the balance Fe before molding and sintering. Graphite powder is added to the mixture to reduce the metallic oxide powders, and the reduced powders are mixed with FeP or FeB powder. The resulting mixed alloy powder is molded and sintered to obtain a member for a movable valve of an internal-combustion engine.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a valve train member for an internal combustion engine, and more particularly, to a valve train member constituting a valve train mechanism for an internal combustion engine used in an automobile or the like. This applies to valve train members of internal combustion engines, such as rocker arms and valve lifters, which require excellent wear resistance in sliding parts with cams and the like.

(Prior Art) A rocker arm converts the rotational movement of a cam into the vertical movement of a valve in a valve train of an internal combustion engine.

Valve lifters and other valve lifters for internal combustion engines must not only have sufficient mechanical properties to withstand complex stresses such as bending, tension, and compression, but also must have sufficient mechanical properties to withstand complex stresses such as bending, tension, and compression. In particular, the sliding parts of the bearings are required to have excellent abrasion resistance, scratch wear resistance, so-called scuffing resistance, and to have little damage to the mating material that moves IM.

Therefore, conventionally, the main body of internal combustion engine valve train members such as rocker arms and valve lifters is generally made of steel members such as carbon steel 5 alloy steel, and the sliding surface with the cam is resistant. Carburizing and quenching treatment to improve wear resistance,
It was common practice to use chill hardening treatment, hard chrome plating treatment, thermal spraying treatment with self-fluxing alloys, etc.

However, carburized and quenched products have poor scuffing resistance, and chill-hardened products have poor durability as sliding members.

In addition, on products treated with hard chrome plating, peeling or abrasion of the hard chrome plating may occur due to localized brightness during internal combustion engine operation, and on products treated with thermal spraying of self-fluxing alloys, there is a risk of peeling off the hard chrome plating due to localized light during internal combustion engine operation. Each of the above-mentioned materials and treatments used as valve train components for conventional internal combustion engines has its own problems, such as increasing the dominance of cams over materials, resulting in severe cam wear. The development of system components is strongly desired.

[Purpose of the invention]

The present invention has been made in order to solve the problems of the prior art described above, and includes blending fine metal oxide powder containing each metal element to form the composition of the mixed alloy powder before molding and sintering. At least one of fine FeP powder and FeB powder is added to and mixed with the alloy powder produced by reducing the mixed powder with graphite powder mixed at the same time, and the mixed alloy powder is used as it is for molding and sintering. The object of the present invention is to provide a valve train member for an internal combustion engine that has excellent wear resistance and scuffing resistance, and can reduce damage to sliding mating members.

[Structure of the invention]

According to the present invention, this purpose is achieved by changing the composition of the mixed alloy powder before compaction and sintering to a weight ratio of C; 1 to 4%, M.
o: 10-40%, Cr: 3-20%, Co: 1-10
%, and P, 0.05~0.8%, B; 0.03~
Graphite mixed simultaneously with a mixed powder containing fine metal oxide powder containing each metal element to create a composition containing at least one type of 0.3% and the remainder substantially consisting of Fe. To the alloy powder produced by reduction with powder,
This is achieved by a valve train member for an internal combustion engine characterized by molding and sintering a mixed alloy powder containing fine FeP powder and FeB powder as it is.

[Action of the invention]

Hereinafter, the effects of the present invention will be explained.

First, the reason for limiting the range of each component constituting the alloy powder used for manufacturing the valve train member of the internal combustion engine of the present invention will be explained.

In addition, in the following description, all contents of alloying elements are expressed in weight ratio (%).

In the present invention, MO reacts with C to form carbides and improves wear resistance, and a part of it is solidly dissolved in the base structure to strengthen the base structure.
If it is less than 40%, the amount of carbide formed will be small, resulting in insufficient wear resistance and the strength of the base structure will be insufficient, resulting in a lot of wear on the valve train parts themselves.If it exceeds 40%, the amount of carbide in the structure will be insufficient. 10 to 40%, as excessive amount will significantly reduce toughness and increase damage to the sliding mating material.
And so.

In addition, like MO, Cr reacts with C to form carbides and improves wear resistance, and a portion of Cr is dissolved in the base structure to increase the strength of the base structure and improve corrosion resistance, so it is effective. However, if it is less than 3%, the amount of carbide formed in the structure is extremely small, resulting in insufficient wear resistance and corrosion resistance.On the other hand, if it exceeds 20%, the amount of carbide formed is too large and the sliding object It is set at 3 to 20% because it increases the damage to the material and significantly reduces the toughness.

In addition, CO is effective because it dissolves in the matrix structure and strengthens it, but if it is less than 1%, the effect is not sufficient, and if it exceeds 10%, the strength will actually decrease. It was taken as lO%.

Furthermore, during sintering of the material of the present invention, P and B are dissolved in the base structure to activate the sintering reaction, and not only enable sintering at a lower temperature, but also improve the stability of the low melting point steadite. It is effective because it forms a phase and densifies the sintered body with the liquid phase, but if P is less than 0.05% and B is less than 0.03%, the above effect is not sufficient, and P is 0.8%, B is 0.3
%, the toughness decreases, so P is 0.05~
0.8%, and B was 0.03 to 0.3%.

In addition, C strengthens the base organization and M o.

Cr, reacts with M6 ClMI Cff+ M,,
l Cs.

It is effective because it forms M and C type carbides and improves wear resistance, but if it is less than 1%, the amount of precipitated carbides is small, so the above effect is not sufficient, and if it exceeds 4%, the M
Most of Mo and Cr form carbides and are solid-solved in the matrix structure.

1 to 1 because the lack of
It was set at 4%.

Next, in the present invention, the reason why graphite powder mixed with a fine metal oxide powder mixture is used for reduction is as follows.

That is, conventional methods for producing alloy powder include (1), spraying method,
■, Grinding method, ■, Reduction method, etc. are used, but in the method of the present invention, since the metal oxide powder that is the raw material is finely pulverized, the reduction temperature during reduction is kept relatively low. The alloy powder particles can be strongly sintered during the reduction process.

The particles are weakly bonded to each other without grain growth, and can be easily ground into fine alloy powder with a particle size of 10 μm or less.

Furthermore, since the fine alloy powder produced by reducing graphite powder has excellent activity, it has excellent sinterability, and alloying and carbide formation reactions can proceed easily.

Therefore, although the alloy powder is a fine powder, it has excellent compression moldability and can be easily compacted by ordinary die molding.

Next, the reason why the valve train member of the internal combustion engine of the present invention has a density ratio of 98% or more and residual pores having round closed pores with a diameter of 5 μm or less is uniformly dispersed. .

If the density ratio is less than 98%, there will be too many residual pores, which will increase the pitting resistance, wear resistance 5, and damage to the mating material on which it slides, so the density ratio is preferably 98% or more.

If the diameter of the residual pores exceeds 5μ, the above-mentioned characteristics will deteriorate, so it is desirable that the diameter of the residual pores be as small as 5μ or less.

Furthermore, the closer the shape of the residual pores is to a round shape, the better the pitting resistance is, and the closed pores improve the lubricating oil retention effect and provide excellent scuffing resistance.

Next, in the valve train member for an internal combustion engine of the present invention, spherical carbides with an average particle size of 10 μm or less are uniformly dispersed in the structure in an area ratio of 10 to 40%. This is because if the average particle size exceeds 10 μm, the damage to the mating material on which it slides increases.

Moreover, the reason why the carbide shape is spherical is that damage to the mating material on which it slides can be reduced.

Furthermore, if the area ratio of carbide in the structure exceeds 40%, the amount of carbide becomes excessive and increases the damage to the sliding mating material, while if it is less than 10%, the amount of carbide in the structure is too small and the valve drive 10 to 40% as it reduces the wear resistance of system parts.
It is better to

〔Example〕

Hereinafter, the present invention will be described in detail based on the accompanying drawings.

Fe, O, powder, Mob, powder with a particle size of 5μ or less.

After reduction, Coo powder, Cr, O, powder, and C powder were blended to give each sample composition shown in Table 1, and wet-mixed in a solvent for 2 hours using a ball mill.

Next, the mixed powder of fine metal oxide powder blended as above was dried and passed through a 100-mesh sieve, and the mixed powder was reduced at 1000°C for 2 hours in ammonia decomposition gas with a dew point of -40°C. Spongy alloys with various compositions as shown in Table 1 were manufactured using the following methods.

Next, FeP powder with a particle size of 5μ or less is added to this spongy alloy.
A mixed powder in which at least one type of FeB powder is added and mixed is pulverized by a pulverizer and passed through a 100-mesh sieve, and the pulverized fine alloy powder is used as it is and subjected to a pressure of 5 ton/cm''. Compacted with
Dew point: 1100°C in -40°C ammonia decomposition gas
A sintering process was performed for 1 hour.

In Table 1, the present invention material (1) has an MO of 25%.

CO; 5%, Cr; 10%, PiO, 3%, C; 3%,
Fe 201 powder with a particle size of 5μ or less; 85 g, M
o Os powder; 38 g, Coo powder; 6 g.

1 containing Cr, O, powder; 15g, c powder; 24g
&P;Add and mix FeP powder equivalent to 0.3%,
Manufactured by the process described above.

In addition, in the present invention material (2), Fe3$53 powder was added in an amount equivalent to 0.1% of B in place of the FeP powder in the present invention material (2), and other fine metal oxide powders were added in the same manner as the present invention material (2). After blending and reduction, FeP powder and FaB powder are added and mixed, and the mixed alloy powder composition before molding and sintering is adjusted to P:0.
B i was set to 0.1% instead of 3%.

In addition, the present invention material (2) is made by combining the FeP powder of the present invention material (2) with P;0
．． 2% equivalent of B and 0.1% of FeB powder were added, and other fine metal oxide powders were mixed in the same manner as in the present invention material to make the mixed alloy powder composition before molding and sintering. Material ■
In place of Pio of 3%, P: 0°2% and Bio: 1%.

Next, the comparative material (■) is P in the present invention material (■).

B is not added, Mo is less than 10%, and Cr is less than 3%.

Comparative material (2) is the same as the invention material (2) in which Co was not added and P was added in an amount exceeding 0.8%.

Comparative material (2) is the same as the present invention material (2) to which B is added in an amount exceeding 0.3%.

The sintered body formed and sintered in this manner was brazed onto a rocker arm, processed into a rocker arm band shape, and assembled into an internal combustion engine as shown in the figure to perform a bench durability test.

In the figure, reference numeral 1 denotes a swing arm type rocker arm, and the rocker arm main body 1a, including the part that contacts the valve 2 and the lash adjuster 3, is made of prepared materials or alloys in the same way as conventional ones.On the other hand, the cam 4 The portion that slides against the rocker arm pad portion 1b is formed of a sintered alloy as described above.

The rocker arm pad part lI) made of this sintered alloy is a
The means for fixing to the arm main body 1a is arbitrary, and for example, brazing, mechanical caulking, casting, or the like may be used.

Note that in this example, a brazing method was used.

” Characteristics of double sintered bodies (hardness Hv), density ratio (%)
, average residual pore diameter (μ) 1 structure (carbide particle size, carbide area ratio)], and the measurement results of the amount of wear on the rocker arm band portion 1b and the amount of cam wear after the end of this bench durability test. It is shown in Table 2.

Table 1 Table 2 As is clear from Tables 1 and 2, the comparative material ■
Since no P or B is added, the MO content is less than 10%, and the Cr content is less than 3%, not only the strength of the matrix structure is low, but also the area ratio of carbides in the structure is low and the amount of carbides is small, so it has excellent wear resistance. The density ratio is 98%.
It is understood that the damage to the mating material on which it slides is increasing.

Comparative material (■) does not contain Co and has a high P content of over 0.8%, so it has low toughness, the base structure does not have sufficient strength, and there are few carbides, so it has poor wear resistance. Furthermore, since the residual pore diameter exceeds 5μ, it is understood that the damage to the sliding mating material is increased.

Comparative material (3) has a high content of B exceeding 0.3%, so it has low toughness and therefore poor wear resistance.

In contrast to the above comparative materials ■ to ■, the present invention materials ■ to ■ all have a high density ratio of 98% or more, an average residual pore size of 5μ or less, and carbides in the structure have an average particle size of 10μ or less. Not only that, but the area ratio of carbides in the structure is 10 to 40%.
, and the cam wear and rocker arm pad wear in bench durability tests were also small, demonstrating excellent properties as a valve train member for internal combustion engines.

〔Effect of the invention〕

As is clear from the following, according to the valve train member for an internal combustion engine according to the present invention, the composition of the mixed alloy powder before compacting and sintering, Fine FeP powder, F
By molding and sintering the mixed alloy powder containing at least one type of eB powder as it is, it has excellent wear resistance and scuffing resistance, and is free from TL scratches on sliding mating materials. It has the advantage of being able to reduce the amount of damage.

[Brief explanation of the drawing]

The figure is a schematic diagram showing a valve train of an internal combustion engine. l------Rocker arm. 1a---1 rocker arm main body. 1b・-11-=Rocker arm pad part. 2-・-・～Pulp. 3・−・−・・Lash adjuster. 4---One cam. Applicant: Toyota Motor Hayashi Shiki Company

Claims (1)

[Claims] 1. The composition of the mixed alloy powder before molding and sintering is changed to In a ratio, C: 1 to 4%, Mo: 10 to 40%. Cr; 3-20%, CoHl ~io%, and P
; 0.05 to 0.8%, Bio, 03 to 0.3%, contains at least lits, and the remainder is substantially Fe.
In order to have a composition consisting of fine gold rIsr! containing each metal element! ! A mixed alloy powder obtained by adding and mixing fine FeP powder and FeB powder to an alloy powder produced by reduction with graphite powder, which was simultaneously mixed with a mixed powder containing compound powder, was used as it was for molding and sintering. A valve train member for an internal combustion engine, characterized by: The valve train member for an internal combustion engine according to claim 1, wherein residual pores having a density ratio of 2.98% or more and having round closed pores with a diameter of 5 μm or less are uniformly dispersed. 3. A valve train for an internal combustion engine according to claim 1, in which spherical carbides having an average particle diameter of 1Oμ or less are uniformly dispersed in an area ratio of 10 to 40% in the structure. System parts.