JPS6346138B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a sintered bearing alloy material, and an object thereof is to obtain a new sintered alloy that has excellent strength and toughness, and also exhibits excellent properties in terms of coefficient of friction and other bearing functions. It is something to do.

Various sintered alloys have been known for use as bearing materials and other materials, but they can be roughly divided into copper-based and iron-based.
Sn, Cu-Sn-C, Cu-Sn-Pb-C alloys, etc.
In addition, iron-based materials include Fe-C, Fe-Pb-C, Fe-Cu, Fe
-Cu-C alloys and the like have been variously proposed and put into practical use. However, in such conventional products, iron-based products have higher hardness than copper-based products, do not necessarily conform well to shaft materials, etc., and are inferior in corrosion resistance. Copper-based materials have the advantage of having excellent physical properties, allowing for thin walls, and being relatively inexpensive. Copper-based materials have a symmetrical relationship with respect to these properties.

In other words, it is natural that the sintered alloy used in this type of bearing should be one that has excellent performance in terms of conformability to the shaft material, corrosion resistance, mechanical strength, etc., as described above, and has been conventionally used. Various studies have been conducted to obtain various sintered alloys, but since the above-mentioned characteristics are technically contradictory, a product that effectively satisfies them has not yet been obtained. Therefore, it is generally believed that copper-based sintered alloys should be used primarily for oil-impregnated bearings, and iron-based sintered alloys should be used for mechanical parts.

The present invention was devised after repeated studies in view of the above-mentioned circumstances, and is made by molding a mixture of 30 to 70% by weight of bronze powder to iron powder.
It is proposed to be sintered at ~950°C to have a porosity of 15-25% by volume, and if necessary, add up to 3% graphite powder, molybdenum disulfide, or a solid lubricant such as molybdenum.

That is, to further explain the present invention, based on the technical concept as described above, the present inventor has developed an iron,
As a result of detailed studies on various sintered alloys using copper and tin, we found that the behavior during sintering differs when copper and tin are combined as single substances and when they are used as an alloy of bronze. I discovered something different. The bronze of the lid is generally wt%,
It has a composition of Cu: 79-90%, Sn: 2-11%, Zn: 1-12%, and also contains a small amount of Pb, etc. Even within these ranges, each Although different properties can be obtained by varying the percentage range of the components, such bronze will in any case have a lower melting point than copper alone. However, when iron, copper, and tin powders are blended as described above, Sn has a relatively low melting point of about 230℃, while Cu has a melting point of 1083℃,
Fe has a high melting point of 1539℃, and these three
Even when mixed metal powders are mixed and molded and sintered, a phenomenon similar to reverse segregation of Sn occurs, and so-called tin sweat is generated, causing the formation of Sn.
This results in the formation of a hard phase with a high content of δ phase, which results in a lack of compatibility with the shaft material, which is desirable as a bearing material. In the case of bronze powder obtained by alloying, even if a graded Fe powder is used, it can only be sintered at a temperature considerably lower than the approximately 1100°C generally used for Fe-based sintered metals. However, during sintering, a part of the bronze component becomes eutectic with iron to create a bronze-iron alloy composition, and in particular, such a bronze-iron alloy composition tends to coat the surface of iron particles. Even products containing a considerable amount of iron powder have a color and feel similar to those of simple copper-based sintered alloys, and the composition is uniform, with the inevitable segregation occurring in iron-copper sintered products. Achieving a sintered alloy with no damage.
It is clear that a composition with a uniform, non-segregating Fe particle surface coated with a bronze-iron alloy exhibits sufficient corrosion resistance. The material of the present invention coated with a high quality alloy has mechanical strength equivalent to or higher than that of conventional iron-based sintered alloys, and also has good conformability to shaft materials etc. due to its bronze coating layer. can get.

The blending ratio of the Fe powder and the bronze powder can be changed as appropriate within the range of 30 to 70% by weight of the bronze powder. That is, if the bronze powder content is less than 30% by weight, it becomes similar to a mere iron-based sintered body and a sufficient alloy layer with bronze cannot be obtained, so that the above-mentioned characteristics of the present invention cannot be effectively obtained. I can't. Furthermore, if more than 70% by weight of bronze powder is used, the above-mentioned core effect of Fe particles cannot be obtained, and its mechanical strength etc. will be close to that of a mere copper-based sintered alloy. When a material with a high Sn content is used, there is a tendency for a hard phase to appear as so-called hard spots, and the object of the present invention cannot be achieved.

The sintering temperature should be adjusted accordingly depending on the amount of bronze powder mixed within the above range. For example, if the bronze powder is 30% by weight (iron powder is 70% by weight), the sintering temperature should be adjusted to 950℃. and if this bronze powder is 70% by weight (iron powder is 30% by weight)
Adopting a temperature of about 800°C is the reason for effectively exhibiting the characteristics of the present invention as described above, and in the case of an intermediate composition relationship between them, the sintering temperature is adjusted according to the degree of operation. . In any case, 950℃
When sintered at a high temperature exceeding 1,083℃, the temperature approaches the melting point of copper (1083℃), which develops a eutectic structure of copper and iron, increasing hardness and tensile strength. The coefficient becomes large, which is not desirable.

The porosity is 15 to 25% by volume, and if it is less than 15% by volume, it is sufficient in terms of strength, but the oil content as an oil-impregnated bearing material is so small that it is difficult to obtain desirable lubrication performance. On the other hand, if the porosity exceeds 25% by volume, the strength and toughness will be extremely poor and the object of the present invention cannot be achieved.

In some cases, the performance can be further improved by adding graphite or other solid lubricants in an amount of 3% by weight or less. A specific manufacturing example of the product according to the present invention will be described below.

Production example 1 Cu: 81.0-87.0wt%, Sn: 4.0-6.0wt%,
Bronze castings consisting of Zn: 4.0 to 7.0 wt% with the balance being Pb and impurities were melted and then sprayed to prepare 100 to 350 mesh of bronze powder and 150 to 250 mesh of iron powder. A bearing material with an outer diameter of 10 mm, an inner diameter of 4 mm, and a height of 8 mm was formed using a mixture of equal amounts of Obtained.

Production Example 2 Using the same bronze powder and iron powder as in Production Example 1, 50wt% bronze powder, 49wt% iron powder, 1wt graphite powder.
% was molded in the same manner as in Production Example 1 and sintered to obtain a bearing material with a porosity of 20% by volume.

In addition, for the production examples of the present invention as described above,
Separately, as Fe-based sintered alloy, 98wt% iron powder and 2wt% copper powder
Comparative Example 1 and the ratio of 90 wt% copper powder to 10 wt% tin powder. Comparative Example 2 was prepared by molding the mixture in the same dimensions as in the production example described above and sintering it at 800°C to have a porosity of 20% by volume, and each of these sintered alloys was treated with the same turbine oil system. The results of testing and measuring the performance of bearings impregnated with lubricating oil are shown in Figure ¹ below. It was confirmed that a significant improvement in bearing performance was achieved, which was superior to that of bearings, and of course it was found to have more favorable characteristics over the entire range than iron-based bearings.

In addition, the mechanical strength of the above-mentioned production examples of the present invention and comparative examples was examined.
The results of measuring the radial crushing strength of the porosity adjusted to 25 vol% together with the case of the above-mentioned porosity of 20 vol% are shown in Figure 2. It was confirmed that it exhibits mechanical strength.

The inventors of the present invention also studied bronze powders having the following component compositions as described above, and were able to obtain similar results with each of them.

Cu: 79-83wt%, Sn: 2.0-4.0wt%, Zn:
8-12wt%, Pb: 3-7wt%.

Cu: 86-90wt%, Sn: 7-9wt%, Zn: 3
~5wt%, Pb: 1wt% or less.

Cu: 86.5-89.5wt%, Sn: 9-11wt%,
Zn: 1.0-3.0wt%, Pb: 1wt% or less.

Cu: 86-90wt%, Sn: 5.0-7.0wt%, Zn:
3.0-5.0wt%, Pb: 1-3wt%.

As explained above, the present invention is equivalent to or better than conventional copper-based sintered alloys in terms of conformability to the shaft material and corrosion resistance, and is superior in mechanical strength to that of conventional iron-based sintered alloys. It is possible to accurately provide a new sintered alloy with special characteristics, and when compression molding it, it has characteristics such as less wear on the mold than with conventional iron-based sintered alloys. This is an invention with great industrial effects.

[Brief explanation of the drawing]

The drawings show the technical contents of the present invention, and Figure 1 is a chart showing the results of measuring the bearing performance of the sintered alloy according to the present invention together with a comparative example using the conventional method. 2 is a chart showing measurement results regarding physical performance.

Claims (1)

[Claims] 1 Cu: 79 to 90 wt%, Sn: 2 to 11 wt%, Zn: 1
Bronze powder containing ~12wt% to iron powder
Molding the mixture with addition in the range of ~70% by weight
A method for producing a sintered bearing alloy material characterized by sintering at 800 to 950°C to have a porosity of 15 to 25% by volume. 2 Cu: 79-90wt%, Sn: 2-11wt%, Zn: 1
Bronze powder containing ~12wt% to iron powder
70% by weight and graphite or other solid lubricant powder in a range of 3% by weight or less.