JPH0814010B2 - Valve guide material and manufacturing method thereof - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a valve guide material made of a sintered alloy having excellent wear resistance and corrosion resistance, which is suitable for a valve guide of an outboard engine, and a manufacturing method thereof. .

2. Description of the Related Art Valve guides for internal combustion engines for automobiles include, for example, Japanese Patent Publication
Although iron-based sintered alloys such as No. 55-34858 are used, iron-based alloys have one drawback in that they easily rust.

For this reason, phosphor bronze alloys have been used in valve guides for internal combustion engines for outboard motors, avoiding iron systems, but existing phosphor bronze alloys do not have sufficient wear resistance, and materials with better characteristics are required. Was there.

Problems to be Solved by the Invention The first aspect of the present invention is that it is superior in wear resistance to phosphor bronze of JIS: C5191 at the operating temperature as a valve guide of an outboard engine, and has a transverse rupture strength and a surface. An object of the present invention is to provide a valve guide material for an outboard engine, which is excellent in hardness and rigidity.

A second aspect of the present invention is, in addition to the object of the first aspect of the invention, a ship having graphite or molybdenum disulfide as a solid lubricant, which is decomposed at a high temperature and cannot be sintered at a low temperature. It is intended to provide a valve guide material for an external engine.

A third aspect of the present invention provides a method for producing the first aspect of the invention, and a fourth aspect of the invention provides a method for producing the second aspect of the invention. The purpose is.

Means for Solving the Problems The first valve guide material for outboard engines of the present invention is 4 to 8% tin, 1 to 4% nickel, and 0.1 to 0.3 phosphorus by weight ratio.
%, And the balance of copper, and is composed of an alloy obtained by sintering a green compact of the shape of a valve guide. The second valve guide material for an outboard engine of the present invention has a weight ratio. Tin 4-8%, Nickel 1-4%, Phosphorus 0.1-0.3%,
At least one of graphite and molybdenum disulfide 1-5
%, And the composition of the balance of the copper, and is made of an alloy obtained by sintering a green compact in the shape of a valve guide.

The third method for manufacturing an outboard valve guide material according to the present invention is such that the composition is 10 ± 2% tin and 0.3 ± 0.1% phosphorus by weight ratio.
And a predetermined amount of the phosphor bronze powder of the balance of the copper and 1 to 4% of nickel are mixed in the copper powder to make the tin 4 to 8%, nickel 1 to 4%, phosphorus
The composition of 0.1 to 0.3% and the balance of copper is formed into a valve guide shape and sintered, and the fourth method for producing an outboard valve guide material of the present invention is tin 10% by weight.
Tin 4 by blending copper powder with ± 2%, phosphorus 0.3 ± 0.1%, and a predetermined amount of phosphor bronze powder with the balance of copper, nickel 1 to 4%, and at least one of graphite and molybdenum disulfide 1 to 5% ~
8%, nickel 1 to 4%, phosphorus 0.1 to 0.3%, at least one of graphite and molybdenum disulfide 1 to 5%, and the balance of copper, characterized by being molded and sintered into the shape of a valve guide. .

Examples Hereinafter, the present invention will be described in detail with reference to its examples.

In this example, atomized phosphor bronze powder having a composition of 10% tin, 0.3% phosphorus and the balance of copper was prepared.

Nickel is an element that alloys with Cu, Sn, and P, and has the effect of strengthening the phosphor bronze matrix and improving heat resistance and wear resistance.

Therefore, to see the effect of nickel with the tin and phosphorus contents fixed, in order to see the effect of nickel on the electrolytic copper part, 57% of this phosphor bronze powder and a predetermined amount of carbonyl nickel powder were added, and the tin and phosphorus contents were Sn. … 5.7%, P… 0.17% Constantly mixed powders of different types with different Ni contents were compressed and molded into a specified shape, and then sintered at a temperature of 820 ° C for 30 minutes using a sintering furnace with an atmosphere of decomposed ammonia gas. A sample having a sintered density of 8.2 g / cm ³ was prepared.

FIG. 1 shows the results of measurement of transverse rupture strength and surface hardness of these samples. In both characteristics, when the Ni content is up to 1%, the content increases sharply with the addition, reaching an index of about 113 when the content is not added to 100, and remains almost constant up to 4%. After that, it gradually decreased, and the transverse rupture strength was about 6% Ni and the surface hardness was 7%, returning to the conventional level not containing Ni. From this result, the proper content of nickel in the present invention is such that the lower limit is 1% for stabilizing the characteristic value and the upper limit is 4% for maintaining stable characteristic.

Next, in order to see the effect of the composition of the base material when nickel is contained, the amount of Ni added to the mixed powder was kept constant at 3%,
Samples with different addition amounts of phosphor bronze powder were prepared. The molding and sintering conditions of the sample are the same as those described above.

FIG. 2 shows the results of measurement of transverse rupture strength and surface hardness of these samples, and the horizontal axis of the figure shows the amount of Sn in the samples. Therefore, for example, in a sample with Sn 6%, P is 3% of Sn.
0.18%, 3% Ni, and the balance of copper, which means that this sample was made from a mixed powder of 60% phosphor bronze powder, 3% nickel powder, and 37% copper powder.

This data shows that the mechanical properties are superior as the amount of phosphor bronze powder compounded increases in the composition range tested, and Sn is required to be at least 4% in order to maintain a level comparable to that of conventional materials. Note that the upper limit of 8% for the Sn content is not a conclusion based on this data, but for another reason. That is, as Sn increases, the amount of sintering deformation due to liquid phase generation increases and the dimensional accuracy is impaired, but the permissible limit corresponds to Sn 8%. Practically, it is preferably within 7%.

Next, the abrasion resistances of the invention material and the conventional material were compared using an Ogoshi-type abrasion tester, and the results are shown in FIG. The test conditions are load 6.3kg, friction speed 2.9m / sec, friction distance 100m.
The friction partner uses heat resistant steel (SUH3), and the test temperature is from room temperature to the valve guide operating temperature (usually about 200 ° C)
The temperature was set to over 300 ℃.

Inventive material 1 in the sample is the same as the 6% Sn sample in FIG. 2, with a sintering density of 8.2 g / cm ³ ; Inventive material 2 is an inventive material 1 containing 3% molybdenum disulfide (the surface of the powder is copper. The sintered density is 8.0 g / cm ³ .
Moreover, the sample of the conventional material is phosphor bronze rod of JIS: C5191 (Cu-6.3%
Sn-0.2% P) is cut.

According to this data, it is natural that the material of the present invention generally has less wear, whereas the conventional material has a large gradient (rate of increase in the amount of wear) in the temperature range of 100 ° C. or higher, whereas the material of the present invention is gentle. Yes, even invention material 1 containing no solid lubricant
The wear at 0 ° C and the wear of the conventional material at 100 ° C are at the same level. Therefore, the alloy according to the present invention is not only superior to the conventional material at the present time, but also has a quality that can be practically used even under more severe operating conditions.

Both graphite and molybdenum disulfide are well-known solid lubricating substances, and if appropriate amounts are dispersed in the matrix, wear resistance is further improved. However, if less than 1%, the effect is poor,
On the other hand, if it exceeds 5%, the strength of the base material decreases, so the addition amount is suitably 1 to 5%. In addition, when mixing it,
It is mixed in the form of multiple powders whose surface is coated with copper, which is the main component of the base material. This is because in the former case, the diffusion is hindered to remain as free graphite; in the latter case, the adhesion with the substrate is enhanced.

By the way, in the production of the alloy according to the present invention, the method of mixing phosphor bronze powder and other components with copper powder without using a single alloy powder containing all components is mainly related to the formability of the powder. Because of the relationship.

That is, although the phosphor bronze powder is usually produced by the atomization method, the shape of the powder is spherical because it contains phosphorus, and the moldability in compression molding is poor in combination with the fact that the material is hard. . Therefore, the overall formability was improved by mixing copper powder having good formability. Therefore, among the copper powders, an electrolytic copper powder having an irregular shape and softness is particularly suitable.

A considerable amount of copper powder is required to improve the formability, and in order to secure 4 to 8% tin and 0.1 to 0.3% phosphorus in the overall composition, the phosphor bronze alloy powder must have high tin and phosphorus concentrations. I have to. However, if it is too high, the formability of the alloy powder further deteriorates. Composition of phosphor bronze alloy powder (tin 10 ± 2%, phosphorus 0.3 ± 0.1
%) Was set in consideration of the equilibrium of this point. The allowable range given to each component is a control limit set as a manufacturing standard for alloy powders, because if the alloy powders have a large variation, the composition must be corrected each time and the quality is a problem.

The raw material powder is molded and sintered by the usual method of powder metallurgy, but the molding density is set high and the sintering temperature is 800 ° C.
Before and after is preferable. Sintering at a temperature of 900 ° C or higher causes excessive liquid phase, which causes deformation and blowout, while 750 ° C
In the following, since the sintering does not proceed sufficiently, the material strength becomes low.

Effects of the Invention As described in detail above, the valve guide material according to the first aspect of the present invention is superior in wear resistance to phosphor bronze of JIS: C5191 at operating temperature as a valve guide of an outboard engine. In addition, it is possible to obtain a valve guide material for an outboard engine, which has excellent bending strength and surface hardness.

The valve guide material according to the second aspect of the present invention is, in addition to the effect of the first aspect of the invention, a solid lubricant made of graphite or molybdenum disulfide that cannot be sintered unless the temperature is low because it decomposes at high temperatures. It is possible to obtain a valve guide material for an outboard engine having the above.

The valve guide material manufacturing method according to the third aspect of the present invention is excellent in formability by mixing phosphor bronze powder and nickel with steel powder, and at the operating temperature as a valve guide of an outboard engine, JIS: It is possible to obtain a method for producing a valve guide material for an outboard engine, which is superior in wear resistance to C5191 phosphorous bronze and is superior in bending resistance and surface hardness.

The method for manufacturing a valve guide material according to a fourth aspect of the present invention has the effect of the third aspect of the invention, is superior in lubricity to molybdenum, and decomposes at a high temperature so that it can be sintered only at a low temperature. It is possible to obtain a method for producing a valve guide material for an outboard engine, which can have the graphite or molybdenum disulfide as a solid lubricant.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between the Ni content and the bending strength and surface hardness of the sintered material, and FIG. 2 shows the relationship between the Sn content and the bending strength and surface hardness of the sintered material. The graph and FIG. 3 are graphs comparing the wear resistance of the present invention material and the comparative material.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Ikenoue 3-26-3 Tokiwadai, Matsudo City, Chiba Prefecture (72) Inventor Koichiro Hayashi 727-25 Minamimasuo, Kashiwa City, Chiba Prefecture (56) References JP 62- 133027 (JP, A) JP-A-55-145107 (JP, A) JP-B 29-958 (JP, B1)

Claims (4)

[Claims] 1. A weight ratio of tin 4 to 8% and nickel 1 to 4
%, Phosphorus 0.1 to 0.3%, and the balance of copper, and a valve guide material for an outboard engine, which is made of an alloy obtained by sintering a green compact in the shape of a valve guide. 2. A weight ratio of tin 4 to 8% and nickel 1 to 4
%, Phosphorus 0.1 to 0.3%, at least one of graphite and molybdenum disulfide 1 to 5%, and the balance of copper,
A valve guide material for an outboard engine, comprising an alloy obtained by sintering a green compact in the shape of a valve guide. 3. By weight ratio, the composition is 10 ± 2% tin and 0.3 ± 0.1 phosphorus.
% And a predetermined amount of phosphor bronze powder in the balance of copper and nickel 1 to 4%
And 4 are mixed with copper powder to have a composition of 4 to 8% tin, 1 to 4% nickel, 0.1 to 0.3% phosphorus, and the balance of copper, and molded into a valve guide shape and sintered. Manufacturing method of valve guide material for engines. 4. By weight ratio, the composition is 10 ± 2% tin and 0.3 ± 0.1 phosphorus.
% And a predetermined amount of phosphor bronze powder in the balance of copper and nickel 1 to 4
%, And at least one of graphite and molybdenum disulfide 1
~ 5% with copper powder and tin 4 ~ 8%, nickel 1 ~ 4
%, Phosphorus 0.1 to 0.3%, at least one of graphite and molybdenum disulfide 1 to 5%, and the balance of copper, and molded and sintered into the shape of the valve guide, the valve guide for an outboard engine. Method of manufacturing wood.