JPS61213336A - Al-sn bearing alloy - Google Patents

Abstract

PURPOSE:To provide resistances for baking and wear at high load, by adding Si, Sr and small quantities of Cu, Ni, Mn to Al-Sn alloy, to ppt. Si particles spherically into Al matrix and to ppt. Al compds. in rod state. CONSTITUTION:Bearing alloy is composed of 3-35wt% Sn, 0.1-10% Pb, 0.1-6% Si, <=3% Sr, 0.1-5% total of >= one kind among Cu, Ni, Mn, and the balance Al substantially. Alloy of the compsn. is cast, ingot is cold worked, then heat treated, to ppt. Si particles spherically, spheroidally or shape approached thereto into Al matrix. Further, compds. of Cu, Ni, Mn with Al are pptd. in rod or fiber state. The bearing alloy is superior in lubricative property, has good mechanical property at high temp. of about 100-250 deg.C and is sufficiently durable for severe using condition under high load operation.

Description

[Detailed Description of the Invention] <Object of the Invention> Industrial Application Field The present invention relates to an Al-3n bearing alloy, and more specifically, Si particles are precipitated in a matrix in a spherical or nearly spherical shape, and Cu, Ni , relating to an Al-8n bearing alloy in which a compound of Mn and Al is precipitated in the form of rods or fibers, which is excellent during high-speed/high-load operation, and has seizure resistance, wear resistance, and fatigue resistance in high-temperature ranges. .

Conventional technology Recently, automobile engines have become smaller, more fuel efficient, and have higher output.As a result, the load on the bearings has increased, the temperature of the lubricating oil has also increased, and the operating conditions for the bearings have become more severe. I am following the path of For this reason, conventional multi-component or Al-based bearing alloys in which a surface layer of PB-3N or the like is formed by overlay plating, etc., suffer from fatigue and seizure phenomena due to the high temperature of the lubricated surface. Recently, there has been a demand for bearing base metals that do not have surface layers such as overlay plating. but,
Even with this type of bearing base metal, it is not always possible to exhibit stable performance under the above-mentioned severe conditions.

First, bearings that require overlay plating on the surface are JIS H5402, AJ-1 (10% Sn, 0.7
5% Cu, 0.5% Ni, AlBaj Riya, JIS H
5402, AJ-2 (6% Sn, 2.5% Cu, 1.
0%N1, Aj! JIS standards such as Bad), SAE 7
80 (6%Sn, 2%Si, 1%Cu, 0.5%N
i.

It is made of a low 5n-Al alloy as shown in SAE standards such as 0.1% Ti, AlBa/). The bearing surfaces of these bearings all require an overlay plating layer of pb-sn alloy. However, in recent years, these bearings have become unusable due to wear and tear of the plating layer under high-load, high-temperature operating conditions. On the other hand,
Bearings that do not require an overlay plating layer are SAE
783 (20% Sn.

0.5%Si, 1.0%Cu, 0.1%Ti, AJB
aj>, it is made of a high 5n-AJ alloy. However, alloys containing a large amount of sn, such as about 20%, have low hardness (the Al matrix becomes weak), so the current situation is that they cannot withstand high loads.

In addition, it has been known for some time that Al-3
PB has been added to n-based alloys to improve lubricity and provide seizure resistance. , 10% Sn, 1.5% Cu.

Ai! containing 0.5% S1! It is described that 3% PB is added to the -8n alloy.

In addition, since pb and Al hardly form a solid solution, in order to improve the dispersibility of pb, an Al-8n alloy in which sb is added in addition to pb is described in Japanese Patent Publication No. 52-12131, and furthermore, an aluminum matrix An Al-8n alloy to which Or is added for reinforcement is described in Japanese Patent Publication No. 18985/1985. However, these Al-3n alloys were developed for the purpose of improving lubricity during normal operation, and have the drawback of not exhibiting sufficient fatigue resistance under high-load operating conditions. The reason for this is that the lubrication mechanism between the shaft and bearing under high load operation is fundamentally different from that under normal operation.

Therefore, basic studies were conducted on the lubrication mechanism under high load operation, and one of them was published in JP-A-58-6433G, in which coarse Si was dispersed and precipitated in an Al-Si alloy.
It is proposed by No.

This bearing has a cutting force made of hard Si precipitates, and because it has the cutting force, the unevenness on the surface of the mating shaft is shaved off and flattened, improving the bearing performance.

In other words, when the mating shaft is made of spherical or flaky graphite cast iron, a recess is left on the surface of the mating shaft after the graphite particles that fell off during polishing, and the hard work-hardened material around this recess remains. Protrusions such as paris and edges are generated,
These uneven parts cause abnormal wear during high load operation. However, in the above bearing, since the cutting force is applied by hard Si precipitates, the uneven parts of the mating shaft are mechanically cut and flattened, and therefore abnormal wear and seizure do not occur. .

However, if the mating shaft is made of a material other than graphite cast iron, during high-load operation, the shaft surface will be irregularly scratched by coarse S1 precipitates, causing seizure and causing a major problem.

Problems to be Solved by the Invention The present invention aims to solve the above-mentioned drawbacks. Specifically, in the conventional At-3n bearing alloy, the amount of Sn is increased or PB is added to improve lubricity. Furthermore, even if sb is added to improve the dispersibility of PB, seizure and abnormal wear will occur during high-load operation, and most cases will occur at high temperatures (100-250℃)
) We propose a bearing base metal that solves the problem of not exhibiting fatigue resistance.

<Structure of the invention> Means for solving the problem and its operation, that is, the bearing base metal according to the present invention has a moldability of 3 to 35%.
%Sn, 0.1~10%Pb, 0.1~G%Si,
Contains 3% or less Sr and at least one or more of Cu, Ni%Mn in a total of 0.1 to 5%, the remainder substantially consists of Al, and furthermore, this matrix contains Si particles. is precipitated in a spherical, elliptical, or similar shape, and a compound of Cu, Ni, Mn, and Al is precipitated in a rod-like or fibrous shape.

Therefore, the structure of this means and its operation will be explained as follows.

First, the Al-3n alloy according to the present invention contains one or more of Sn, Pb, Si, and Cu, Ni, and Mn as main components. At this time, the reason for adding Sn, Pb, etc. is mainly to improve lubricity and conformability, but the main feature is that Si particles are formed in an Al matrix in a spherical, elliptical, or even at least partially 5n-P is precipitated in a rounded shape, and 5n-P is deposited near the 81 particles.
By agglomerating alloy particles, the lubricity under high temperatures and high loads is greatly improved, and intermetallic compounds of Cu, Ni, Mn and At are precipitated in a rod-like or lll-like shape. The objective is to improve the strength at temperatures up to 250°C.

In general, the process by which the image sticking phenomenon is achieved is complex and is achieved through the synergistic action of many conditions, so it is difficult to understand it unambiguously.

However, in Cu-Pb bearing alloys with Pb-Sn alloy overlay plating formed on the surface, the plating layer wears out and seizes under high load operation, whereas Al-
We focused on the fact that 3n-pb-si-Cu alloy bearings have a phenomenon in which seizure does not occur even though no overlay plating layer is formed on the surface, and we compared the structures of both bearings.

That is, FIG. 8 is an enlarged cross-sectional view of a part of the bearing having overlay plating ■ on the surface, and FIG.
FIG. 3 is an enlarged cross-sectional view of a portion of an n-Pb-3i-Cu alloy bearing. As is clear from FIG. 8, this bearing consists of an overlay plating layer 5 on the front surface, a bearing base metal 6, and a back metal 7, and the load is supported by the entire surface of the overlay plating layer 5.

On the other hand, as shown in Fig. 9, ^l-8n-Pb-3
A bearing made of an i-Cu alloy consists of an alloy layer 6 and a back metal 7, and rod-like flake-shaped Si particles 2 are precipitated in the alloy layer 6 and the matrix. Therefore, in this bearing, the load is supported by the hard Si particles, and moreover, the Si particles have the cutting force as described above.

In short, the difference between the two is surface contact and point contact, and this difference results in a decisive difference in lubrication and temperature rise on the friction surface.Especially in surface contact as shown in Figure 8, friction occurs under high speed and high load conditions. The temperature of the surface increases rapidly, while the temperature of the 9th
In point contact as shown in the figure, a gap is formed between the surface of the alloy layer 6 and the surface of the mating shaft, and since no large load is applied to the oil film in this gap, sufficient lubrication is maintained and the temperature of the friction surface is The rise can be suppressed.

Therefore, based on the basic viewpoint that supporting the shaft load by this is extremely effective for lubrication under high loads, the present inventors have developed the present invention by researching the composition and structure to make the most of the effect. This led to the completion of such a bearing base metal. Specifically, the present inventors have discovered that Al −
Focusing on the precipitation form of Si in 8n-Pb-3i-Cu bearing alloys, we conducted research on the effect of this form on the lubricating surface. First, we found that Si is a stable substance with a high melting point, and Si has strong non-metallic properties and does not diffuse or dissolve at all even if it comes into contact with Fe, the main component of the mating shaft, at a temperature of about 20°C to 500°C. It was found to be extremely suitable.

Second, when point-supporting the mating shaft through an oil film, Si particles are hard enough to reach a Vickers hardness of 599, and since they are not a compound, they are not brittle and have high elasticity, so they cannot handle sudden fluctuations in load. It was found that it can withstand

However, although Si has the above properties, it has strong crystallinity, and even in the form of eutectic precipitation with Al,
It has a plate-like or rod-like shape, and its shape changes only slightly even if it undergoes rolling or heat treatment during the bearing manufacturing process. Therefore, if the precipitation form of the Si particles is not controlled, the Si particles 2 in the matrix 1
becomes plate-shaped or rod-shaped and separates from the Si particles 2.
-pb alloy particles 3 are present. In this state,
The edges of the hard Si particles tend to scrape and damage the mating shaft, which in turn reduces lubricity and causes seizure.

From this point of view, the present inventors removed the cutting force from the Si particles and controlled the shape so that the edges were rounded, such as spherical, in order to dramatically improve the lubricity.

That is, FIG. 2 is an enlarged cross-sectional view of a part of the bearing base metal according to one embodiment of the present invention, and as shown in FIG. 2, the Si particles 2 dispersed and precipitated in the matrix 1 are spheroidized,
These spherical particles 2 bring the ideal point contact closer to the ideal, further improve lubricity, and prevent damage to the mating shaft even when high loads are applied rapidly and rapidly.

This spheroidization of Si particles is caused by the eutectic A1 in which Sl precipitates.
It has been found that this can be achieved by improving the properties of the alloy liquid phase, and that Sr is particularly effective as an additive element.

Further, when S'' is added, the precipitation form of the 5n-Pb alloy particles 3 changes, and as shown in FIG. 2, the 5n-Pb alloy 3 comes to exist adjacent to the spheroidized Si particles 2. This structure dramatically improves the lubrication performance compared to the conventional structure (see, for example, FIG. 10).

In addition to finding a theoretical solution to the surface performance as described above, it is also necessary to consider strengthening the A/7 trix at high temperatures. In other words, Al is highly sensitive to heat and 150
If the temperature is too high, it will soften (below HvlO) and lose its strength.

Therefore, in order to prevent this softening, research has been conducted on structures that can resist deformation forces by precipitating compounds that are stable even at high temperatures.As a result, 5 to 3
When precipitated in the form of rods or fibers with a length of about 0μ,
It was confirmed that the strength increases at high temperatures. This is Al
This means that the matrix is reinforced with fibers using an intermetallic compound.

FIG. 1 simply shows the improved cross-sectional structure.

To explain in more detail, in the bearing with the structure shown in Fig. 1,
Si particles 2 whose lubricated surfaces protrude from the surface of matrix 1
Moreover, an oil film is interposed between the Si particles and the mating shaft to maintain fluid lubrication. However, this oil film ruptures when subjected to a rapidly fluctuating load and locally reaches boundary lubrication, and if a 5n-Pb alloy film is present on the top surface of the Si particles 2 at this time, seizure can be prevented. The oil film is normally regenerated and the state of fluid lubrication can be quickly restored. At this time as well, with the structure shown in Figure 1, 5n-pb alloy particles 3 exist near S; particles 2, and this alloy has affinity even in the molten state, which causes oil to run out. Hateful. Furthermore, even if the Si particles become high in temperature due to friction between the mating shaft and the Si particles, the heat is absorbed by the heat of fusion of 5n-Pb, making it difficult for the mating shaft to seize with the AJ alloy in the matrix nearby. Also, at this time, as shown in FIG. 3, at least a part of the 5n-Pb alloy particles 3 adjacent to the Si particles 2 is in a liquid phase, and this liquid phase 3a is supplied to the protruding surface of the Si particles 2. Ru.

This supply amount increases by 75% as the temperature rises, and since the 5n-Pb liquid phase 3a is always present on the lubricated surface of the Si particles 2, overheating can be prevented.

In short, the structure in which the Si particles 2 are spherical and the 5n-Pb alloy particles 3 are adjacent to them is very effective in the boundary lubrication state (oil film has broken), and even in the normal fluid lubrication state, the structure in which the hard Si particles The particles 2 suitably adapt to the mating shaft and are covered with a soft 5n-Pb alloy layer, which acts as a shock absorber.

Furthermore, in order to obtain an excellent lubricating surface, Si particles and 5n-P
b A strong Al matrix is required to support the alloy particles, and for this purpose, at least one or more of Cu, Ni, and Mn is added to precipitate intermetallic compounds with Al in the form of rods or fibers. However, the amount is 5% of the total amount
If it exceeds this, the compound will become coarse and its toughness will deteriorate, so the appropriate amount to add is 0.1 to 5% in total. In addition, 8 mouths also have a pb of 0.0 in the range of 3 to 35%.
An appropriate lubricating surface can be formed within the range of 1 to 10%.

Example Next, examples will be described.

First, an Al-3n alloy having the composition shown in Table 1 was cast as a plate material with a thickness of 2010 m by continuous casting, and the upper and lower surfaces of each casting billet I. It was rolled down to a thickness of 2n+m by cold rolling on the 0mm-faced surface side. 300 in this state
A heat treatment at ~350° C. was performed to remove strain, and then a thin plate of pure Al was crimped onto an iron backing plate to obtain a bearing with a thickness of 1.50 mm.

Table 1 Among these bearings, 1 has Sr added to the test material and Si
The sample material Nt2 is N1, Mn is &, 1
In addition to the above components, Ns, 3 is based on the present invention in which Cu is roughly added to Nl2 to precipitate the compound.

Each of these test materials was used as a bearing at room temperature to 25°C.
To check mechanical properties down to 0°C, room temperature (25°C)
Tensile strength and elongation tests were conducted under six conditions: , 50°C, 100°C, 150°C, 200°C, and 250°C, and the relationships shown in Figures 4 and 5 were obtained. In addition,
The back metal of each sample material was removed by machining to leave only the Al-3n alloy portion, and the shape was as shown in No. 5 of JIS Z 2201.

These results show that sample material 2.3 has a particularly high ``zio''.

There was not much decrease in strength at ~250°C, and Cu,
The effect of adding Ni and Mn can be seen. In addition, the structure of this sample material 2.3 is Cu, Ni%M as seen in Figure 1.
A compound of n and Al was precipitated in a rod shape.

Next, in order to find out the friction performance of the surface of these test materials,
The test was carried out using a Suzuki type abrasion tester, and the test conditions were as follows.

Surface pressure 10kgf/I] 2~100klJf/I
)' 10kof/c12 5tep every 15 minutes until
Upload it.

Masatsu speed 411/sea Mating material 845C% Hardness HRC-55 Surface roughness 0.
8-1. O3 Oil used: SAE, 20w-40 Oil temperature: 150°C±5°C The results are as shown in Figure 6.

According to C, all of Sample Materials 1 to 3 show good friction coefficient values, and it can be seen that the friction performance is hardly affected by the compounds of cu, Nt, and vn.

Incidentally, under a load of 100 kgf/all, the friction coefficient of sample material 3 shows an excellent value of 0.011.

Next, each sample material was actually processed into a bearing shape and an Underwood fatigue test was conducted to check the final bearing performance, and the results shown in Figure 7 were obtained. This is the length of time that performance was maintained without seizure when the bearing was fixed to the connecting rod housing and an eccentric load was applied to the shaft under the following conditions, almost the same as in an actual engine. This is a test to evaluate.

Surface pressure 600kgf/c12 Rotation speed 4000r, p, m/min Phase wheel shaft material F
C lower 0, roughness 0.8~1.5S oil used 20w
-40 (SAE) Oil temperature 170°C±10°C The upper limit of the test time was 250 hours. This final check also shows that the alloy of the present invention with added durability at high temperatures is an alloy system with excellent structure.

The alloy of the present invention, which was developed by focusing on the structure of the lubrication surface and its lubrication mechanism, is recommended as an A1 alloy bearing for high-load, high-speed operation.

<Effects of the Invention> As explained in detail above, the present invention has a weight percentage of 3 to 35
%Sn, 0.1-10%Pb, 0.1-6%Si,
Contains 0.1 to 5% in total of 3% S or less and at least one or more of Cu%Ni and Mn, with the remainder substantially consisting of At, and furthermore, this matrix contains 81 particles. is precipitated into a spherical, elliptical, or similar shape, and a compound of Cu, Ni, Mn, and Al is precipitated into a rod or fiber shape.

The bearing alloy of the present invention with these configurations has extremely excellent lubricity, has extremely good mechanical properties at high temperatures of 100 to 250°C, and is a bearing base metal that can fully withstand harsh usage conditions due to high-load operation. be.

[Brief explanation of drawings]

FIG. 1 is an enlarged cross-sectional view of a part of a bearing base metal according to one embodiment of the present invention, FIG. 2 is an enlarged cross-sectional view of a part of a bearing in which Si particles are sphericalized to improve lubricity, and FIG. is an explanatory diagram of the lubrication mechanism of the bearing base metal shown in Figure 2, Figure 4 is a graph showing the relationship between temperature and tensile strength when the bearing base metal according to the present invention is compared with a comparative material, and Figure 5 is a graph showing the relationship between the bearing base metal according to the present invention and a comparative material. A graph showing the relationship between temperature and elongation in comparison, Fig. 6 a graph showing the relationship between load and coefficient of friction in comparison with the comparison material, and Fig. 7 a graph showing the durability time of each test material in comparison with the comparison material. 8 and 9 are enlarged sectional views of a portion of a conventional bearing, and FIG. 10 is an enlarged sectional view of a portion of the bearing base metal of FIG. 9. Code 1...Matrix 2...Si
Particles 3...5n-Pb alloy particles 3a...5n-Pb liquid phase 4...II fibrous intermetallic compound 5...Overlay... ...Bearing alloy layer 7 ...Backing metal patent applicant KonuDC Co., Ltd. Representative Patent attorney Yoshikatsu Matsushita Lawyer Fumihiro Soejima@I Figure 1! 2 Figure 53 tl! 5 Figure 4 Warm friend (°C) Figure 5 &('C) m6 figure! ! Figure 7 Takomata R4

Claims (1)

[Claims] 3-35% Sn, 0.1-10% Pb, 0.1% by weight
~6% Si, 3% or less Sr, and at least one or two or more of Cu, Ni, and Mn in total of 0.1
~5%, with the remainder essentially consisting of Al, and furthermore, Si particles are precipitated in a spherical, elliptical, or similar shape in this matrix, and Cu, Ni, Mn
An Al-Sn bearing alloy characterized by being formed by precipitating a compound of and Al in the form of a rod or fiber.