JPS6144141B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an aluminum alloy bearing, and more specifically, to an improvement in a lead-containing aluminum alloy bearing used as a bearing for an internal combustion engine. The above-mentioned aluminum alloys containing tin are generally used as bearings by being pressure-welded to a backing steel plate. Lead, like tin, is a soft element;
Like tin, it imparts bearing performance to aluminum alloys, but it is difficult to disperse uniformly in the alloy, so it is not used as frequently as an alloying element. However, tin and lead have physical properties in common, and are common in that they provide conformability as one of bearing performance. Note that conformability here refers to the degree to which the surface of the bearing is designed to ensure that the bearing and shaft are always in contact with each other with a film of lubricating oil interposed between them, relative to the machining accuracy of the shaft, which is the mating material of the bearing. Refers to the property of a bearing that is partially scraped or worn away by the shaft during the early years of bearing use. The conventional method has been to incorporate tin or lead into aluminum, thereby creating compatibility. A few words about the manufacturing method of bearings.In order to increase the adhesive strength between the bearing alloy formed by casting and rolling and the backing steel plate, it is essential to annealing the bearing alloy after pressure welding. The process is carried out for a long time at a temperature lower than that at which Al-Fe intermetallic compounds are formed. However, when tin and/or lead-containing aluminum alloys are exposed to high temperatures during the above-mentioned annealing, aluminum crystal grains and tin or lead crystals become coarse in the alloy structure, resulting in tin and/or lead-containing aluminum alloys. The drawback was that the high-temperature hardness and fatigue strength of the steel were reduced. Therefore, according to recent technology, a proposal has been made to strengthen the aluminum base and improve bearing performance by adding a metal harder than tin or lead to the aluminum alloy. Referring to examples of tin and/or lead-aluminum alloys, e.g.
3.5~4.5% Sn - 3.5~4.5% Si - 0.7~1.3% Cu - Remaining
Al, 4-8% Sn-1-2% Si-0.1-2% Cu-
0.1~1%Ni-Remaining Al, 3~40%Sn-0.1~5%Pb
−0.2~2%Cu−0.1~3%Sb−0.2~3%Si−
0.01~1%Ti-Remaining Al, 15~30%Sn-0.5~2%Cu
-Remaining A, and 1~23%Sn-1.5~9%Pb-0.3~
Aluminum-based bearing alloys containing tin (hereinafter referred to as multi-component bearing alloys) such as 3% Cu-1 to 8% Si-remaining Al have been used. However, in recent years, internal combustion engines for automobiles have been required to be smaller and have higher output, and as it has become necessary to install blow-by gas reduction devices to purify exhaust gas, the usage conditions for internal combustion engine bearings have changed. It has become worse than before. In other words, as bearings in recent years have become smaller and used under higher loads and higher temperatures than before, conventional multi-component bearing alloys are prone to fatigue failure and abnormal wear, which is one of the causes of troubles in automobile internal combustion engines. I was getting used to it. Fatigue phenomena in metal materials generally occur when the material is used for a long period of time, but in modern internal combustion engines, bearings can break due to fatigue even when high-load operation continues for a relatively short period of time. sometimes happened.
This is because the lubricating oil in the internal combustion engine becomes hot during high-load operation, and for example, the temperature of the lubricating oil in the oil pan reaches 130 to 150°C. It is predicted that the bearing alloys will be sliding at considerably high temperatures, and as a result, the high-temperature hardness of conventional multi-component bearing alloys will rapidly decrease, and tin will melt or migrate, which will reduce fatigue strength. The inventor of this application believes that this is the cause. The applicant of the present application proposed an aluminum alloy containing 2.5 to 25% tin, 0.5 to 8% zinc, and 0.1 to less than 0.1% chromium by weight percentage in Japanese Patent Application No. 1985-851, and the present application The applicant, in Japanese Patent Application No. 55-852, stated that the weight percentage is 2.5 to 25%.
of tin, 0.5 to 8% bad lead and/or 7%
silicon, chromium, manganese, nickel, iron, zirconium, molybdenum, cobalt, tungsten, titanium, antimony, niobium, vanadium,
An aluminum-based alloy containing at least one element selected from the group consisting of cerium, barium, and calcium, with the balance substantially consisting of aluminum has also been proposed. In these aluminum alloys, silicon, chromium, etc. are extremely fine hard Al.
-Cr is dispersed in the matrix as an intermetallic compound and has the effect of mainly preventing the coarsening of tin particles, and zinc is mostly dissolved in the matrix to strengthen the matrix, thereby improving the fatigue resistance of the alloy. Strength and high temperature hardness are improved. The bearing performance of these aluminum-based alloys is improved by the synergistic effect of both matrix reinforcement and fine dispersion reinforcement compared to the case of either single action. In the above-mentioned Japanese Patent Application Nos. 55-851 and 1985-852, it is understood that soft tin and/or lead particles achieve excellent conformability. The above-mentioned approach to compatibility is an established way of thinking in the industry, and the idea of imparting compatibility to bearings using soft tin and/or lead particles is in line with the conventional way of thinking in the industry. It can be said that it is an extension of that. Furthermore, the effects of chromium, silicon, etc. are viewed from the perspective that these particles prevent the coarsening of tin and/or lead particles, so to speak, the particles of chromium, silicon, etc. directly improve compatibility. The above patent application was filed based on the technical idea and the technical means described below to indirectly improve the compatibility of tin and/or lead-containing aluminum alloys by controlling the shape of soft tin and/or lead particles. The description can be said to be consistent. The present inventor conducted detailed research on the bearing performance of lead-containing aluminum alloys, and found that it is possible to dramatically improve bearing performance, especially conformability and seizure resistance, by using technical ideas and means that are completely different from conventional thinking. They discovered this and completed the present invention. As described in detail later, this technical means is the control of the size of silicon particles in lead-containing aluminum alloys, but silicon particles precipitate or crystallize (hereinafter referred to as crystallization for convenience) in Si-Al binary alloys. It is a well-known fact that silicon particles are distributed in aluminum-based bearing alloys for internal combustion engines. According to JP-A No. 55-82756, in the production of bearing alloys, an aluminum alloy consisting of 5 to 15% silicon, 5% or less copper, 10% or less bismuth, and 1% or less lead is heated or cold. By rolling or extruding, a cross-section reduction of at least 90% is obtained, so that the silicon particles in the alloy are present in the form of finely divided particles rather than in a continuous skeleton-like network. An invention has been proposed to do so. It is also stated that this bearing alloy is useful for both bearings with and without soft plating (overlay). The key point of this invention is to finely disperse the coarse silicon particles in the cast state by rolling, etc., and to limit the annealing performed as necessary after rolling to the extent that the processed structure is restored.
The point is that the fine morphology of silicon particles is maintained. Furthermore, since this invention specifies that a high silicon content of approximately 10% is preferable, it has been found to be meaningful to finely disperse silicon particles, which grow quite large in aluminum alloys with high silicon content. There is. However, according to the research of the present inventor, in bearing alloys for internal combustion engines used without overlay, high silicon content reduces the fatigue strength of the bearings, especially when bearings are subjected to repeated loads from the shaft. It has been found that there is a drawback in that fatigue fracture occurs when sliding under stress, resulting in a significant decrease in load capacity. Further, for the purpose of improving bearing performance, satisfactory results cannot be obtained by methods such as rolling that finely disperse silicon particles. In other words, aluminum alloys for bearings are usually produced by giving predetermined dimensions to cast materials by rolling or other methods.
The silicon particles are divided by this rolling, etc., but in addition to dividing the silicon particles in this way, in some cases, the silicon particles are coarsened and the number of silicon particles of a prescribed size is controlled to a prescribed number. It was found that bearing performance was significantly improved. By the way,
In the above publication, experiments were conducted on an aluminum alloy containing 11% silicon, and the size of the silicon particles ranged from 0.0001 inches (2.5 microns) to 0.001
inch (25 microns), but there is no mention of the number per unit area. Alumi−nium of SAE Technical PaPer Series
Based Crankshaft Bearings for the High
Paper entitled Speed Dierel Engine (February 1981)
23-27, in Detroit) is a paper published by the same person as the above publication, in which 11% Si
The seizure load for -1% Cu-Al alloy is listed. According to this, silicon particles with a size exceeding 17 microns have a particle size of 8.7× per unit area (m ² ).
It is explained that if there are ¹⁰⁶ particles, there will be a lot of variation in the seizure load, while if there are 0.6 x ¹⁰⁶ particles larger than 17 microns, the seizure load will be higher and less variable. This and other theoretical explanations are that the fine dispersion of hard silicon particles in the aluminum matrix contributes to improved compatibility and seize load. moreover,
In the above paper, the concept of ``compatibility'' is contradictory to the concept of ``compatibility,'' which refers to ``adaptability,'' which allows for misalignment between the crankshaft and the shaft.
It is stated that silicon-containing aluminum alloys need to be provided with an overlay because of their low conformability. Therefore, although there has been a concept focused on silicon particle size in conventional aluminum alloy bearings, there has been no example of success in providing an aluminum alloy that can be used as a bearing without an overlay. In addition, it was known that silicon particles are hard and directly abrade the mating material (steel crankshaft, etc.), directly affecting conformability or compatibility. This was done by applying the theory that fine hard particles are uniformly dispersed in the material, and this theory itself is inherent in, for example, the applicant's earlier patent application, and is well known in the field of sliding materials. This is one theory that has been developed. The present invention is based on a theory that is completely different from the prior art as described above, and is a lead-containing aluminum alloy that has significantly higher conformability and seizure load than the prior art and can be used as a bearing without an overlay. The company provided bearings. The aluminum alloy bearing according to the present invention contains at least 0.1 to 10% by weight of lead, cadmium, indium, thallium, and bismuth selected from the group consisting of lead, cadmium, indium, thallium, and bismuth (hereinafter referred to as lead, etc. when referring to all of these elements). Type 1 and 0.5 to 5%
an alloy containing less than or equal to 50% silicon, the remainder being substantially aluminum, is adhered to a backing metal, and the size (of the silicon particles) measured by the major axis of the silicon particles in the aluminum alloy is 5 microns or more and 40 microns or less The aluminum-based alloy bearing has at least 5 silicon particles per 3.56×10 ⁻² mm ² in any part of the alloy, and can be used without an overlay. Hereinafter, the constituent elements of the present invention will be explained in the order of chemical composition, silicon particles, and bearing structure. First, regarding the chemical composition, lead and the like are elements that change the properties of the aluminum alloy into soft ones, giving it lubricating performance and conformability suitable for bearings. Familiarity here is defined by a technical concept that is generally accepted in the industry as described above, and is hereinafter referred to as familiarity of the general concept. If the content of lead or the like exceeds 10%, the general conformability and lubricity improve, but the hardness of the aluminum alloy decreases and the strength as a bearing decreases. On the other hand, if the content of lead etc. is less than 0.1%, the general concept of aluminum alloy as a bearing alloy will not be compatible. Addition amount of lead etc. from 0.1 to 10
% range should be determined appropriately depending on the application, but generally speaking, when the load applied to the bearing, that is, the explosive load applied via the piston of an internal combustion engine, is large. It is better to keep the content of lead etc. low, for example 0.5 to 4%, and when it is small, increase the content of lead etc. On the other hand, if there is a concern about bearing seizure due to high load and high speed rotation, the content of lead etc. may be increased, for example 4 to 8%. In order to ensure that the fatigue strength and high-temperature hardness of aluminum alloys containing lead, etc. are sufficient for the performance required for bearings, it is desirable that particles of lead, etc. be finely dispersed in the alloy. . However, lead in particular is an element that is difficult to finely disperse. However, in the present invention, since the special running-in effect described later is substantially responsible for the bearing performance, there is no problem in using it as a bearing for an internal combustion engine, even if the miniaturization of particles such as lead is not so important. The preferred content of lead etc. is 1 to 6%. Silicon is an element that brings about a special conforming effect, which will be described later.If its content is less than 0.5%, the conforming effect will be insufficient, while if it is more than 5%, fatigue strength and seizure load will tend to decrease, and the shaft will wear out. let The preferred silicon content is between 2 and less than 5%. Next, silicon particles will be explained. According to the inventor's findings, a special running-in effect that does not appear when the major axis dimension (hereinafter simply referred to as dimension) of silicon particles is less than 5 microns appears when it is 5 microns or more, dramatically improving the bearing performance of aluminum alloys containing lead, etc. let This effect is observed when 5 or more silicon particles of 5 microns or more are present per 3.56 x 10 ^-2 mm ² , and becomes more pronounced as the number increases. On the other hand, if the silicon particle size exceeds 40 microns, the fatigue strength of aluminum alloys such as lead will decrease. As mentioned above, the upper limit of the silicon content in the alloy of the present invention is 5% or less (excluding 5%), which is lower than the silicon content of the eutectic or hypereutectic of the Si-Al binary system. Regarding the silicon content, and from the above, the aluminum alloy of the present invention is characterized by having a low silicon composition and crystallizing coarse silicon particles. In addition, the significance of specifying coarse silicon particles, that is, silicon particles with a size of 5 microns or more as a component in the present invention, is that, in a negative sense, fine silicon particles do not contribute to improving bearing performance. In this respect, the bearing performance of conventional aluminum-based alloy bearings is considered different. In other words, in a previous application by Dekao, fine silicon particles indirectly improve bearing performance through controlling the shape of tin and/or lead particles, as mentioned above, and the paper in the SAE journal mentioned above theoretically improves bearing performance. Experimental data also shows that finer silicon particles provide better bearing performance. however,
In the present invention, coarse silicon particles have much better performance other than fatigue strength. Therefore, if we were to actively discuss the significance of coarse silicon particles, we would be concerned with minute irregularities caused by the machining accuracy of the shaft, which is the mating material of the bearing containing such silicon particles, or by the lapping effect on the surface of the shaft when the shaft is made of spheroidal graphite cast iron. It is thought that the silicon particles flatten the area around the recesses created by graphite falling off from the bearing, and that good sliding occurs between the bearing and the shaft with an oil film always present. In the field of conventional bearings, the general idea is that soft components such as tin and lead contribute to the conformability of aluminum alloys, and the idea is that hard particles directly contribute to flattening the unevenness of the mating material. teeth,
As far as the present invention is aware, there is no such explanation other than the above-mentioned SAE magazine, so the conforming effect by silicon particles is referred to as a special conforming effect. However, the SAE journal emphasizes that this action of silicon particles, which improves compliance, has the opposite effect on compliance, and as a result the bearing must have an overlay. Here, compatibility is the performance of a bearing that can adapt to machining misalignment between the shaft and the bearing, so it is semantically equivalent to conformability (compatibility based on a general concept). Therefore, neither in the SAE journal nor in any other published papers to the best of the inventor's knowledge, there is no idea that hard particles scrape away the surface irregularities of the mating shaft, flatten it, and contribute to conformability, and even more No experimental data has been published showing that the presence of more hard particles in a bearing improves seizure load and other bearing performance. Therefore, the above-mentioned special running-in effect is a feature of the present invention, and bearing performance, such as seizure load, is significantly improved when compared with materials that only have a conventional running-in effect in the general concept. Of course, the alloy of the present invention contains lead, etc., but the embedding of the soft metal into the surface of the mating material due to the general concept of conforming action is achieved after the unevenness of the mating material is flattened by a special conforming action. As a result, it is believed that the combination of both will provide excellent performance as a bearing for automobile internal combustion engines. The above-mentioned special running-in effect is particularly effective when the mating shaft is made of spheroidal graphite cast iron or flaky graphite cast iron. Spheroidal graphite cast iron tends to be used in place of conventional forged shafts to reduce the cost of shafts for internal combustion engine crankshafts, etc., but graphite particles are scraped off from the shaft surface during shaft polishing.
The traces of the fallen spheroidal graphite particles are many depressions or cavities, and the iron-based matrix around them is work-hardened sharp burrs or edges. Conventional aluminum-based bearing alloys containing tin and/or lead have had the problem that these burrs cause abnormal wear on the bearing surface. According to the inventor's research, the soft aluminum matrix is scraped off by the burr and incorporated into the recess, and this aluminum and the aluminum of the bearing material are very likely to stick together due to lack of flexibility, resulting in seizure immediately. It also became clear that However, in the lead-containing aluminum alloy according to the present invention, the coarse silicon particles scrape away the burrs and make the area around the recesses smooth. As a result, seizure does not occur even under high loads, and seizure resistance is significantly improved. The thickness of the bearing alloy mentioned above is 0.1~1mm, especially 0.2~
0.5mm is preferred. Apply anti-rust oil to the bearing alloy if necessary. The bearing of the present invention has a structure that does not require an overlay because it has excellent seizure resistance for the reasons described above. Further, the bearing alloy is bonded to a backing plate with or without a base by pressure welding or the like. The lead-containing aluminum alloy of the present invention has (A) 0.1
2% to 2%, preferably 0.2 to 1% of at least one of copper and magnesium (hereinafter referred to as copper etc.), and/or (B) 0.1 to 1%, preferably
It may further contain 0.1 to 0.6% of at least one of chromium and manganese. Copper and other materials increase the hardness of aluminum alloys containing lead and other materials, contributing to improving the fatigue strength of bearings. If the content of copper, etc. is less than 0.1%, the hardness improvement effect will be small;
If it exceeds this, the aluminum alloy containing lead etc. will become too hard, impairing its rolling properties, and will also reduce its seizure resistance and corrosion resistance against lubricating oil. The hardness improvement effect of copper etc. becomes even more pronounced when it coexists with chromium.
Hardness does not decrease much even at temperatures above 200℃. Chromium and manganese have the effect of increasing the hardness of aluminum-based alloys containing lead, etc., preventing or mitigating softening at high temperatures, and preventing coarsening of lead, etc. particles at high temperatures. A portion of chromium and manganese forms a solid solution in the aluminum matrix and causes solid solution strengthening, shifts the recrystallization softening temperature to a higher temperature side, and further increases work hardenability.
The increase in recrystallization softening temperature occurs in the high temperature range to which internal combustion engine bearings are exposed (oil pan temperature of 130 to 150 degrees Celsius).
However, the high-temperature strength of the bearing alloy is maintained well, and desirable results can be obtained in terms of fatigue resistance and load-bearing capacity. The parts of chromium and manganese that are not solidly dissolved in the aluminum matrix are Al-Cr.
(Mn) precipitates extremely finely as an intermetallic compound,
Prevents particles such as lead from becoming coarse due to annealing during bonding of the bearing alloy to the back metal or due to high temperatures inside the internal combustion engine. The hardness of this Al-Cr(Mn) intermetallic compound is about 370 on the Pickers hardness, which is relatively small since the hardness of silicon particles is about 1000. Because of this difference in hardness, Al-Cr (Mn) intermetallic compounds prevent particles such as lead from becoming coarser and improve the conforming effect of the general concept, while silicon particles improve the conformability of the mating material axis. It is thought that the unevenness is flattened to achieve a special conforming effect. A content of 0.1% is necessary to provide the above-mentioned benefits of chromium and manganese, while above 1% chromium and manganese precipitate as coarse Al-Cr(Mn) intermetallic compounds. Therefore, it is undesirable. Next, a method for controlling the size and number of silicon particles will be explained. Generally, in Al-Si alloys, most of the silicon crystallizes out as needle-shaped eutectic crystals during the casting process, and during the process of rolling the cast alloy to the required thickness for the bearing, the crystals are fragmented and reduced in size.
Most of the silicon particles in the Al-Si alloy thin plate obtained by this casting-rolling method are less than 5 microns, and although there are rare particles less than 10 microns, the number per unit area is small, and the size of the particles is small. or flake-shaped. Further, intermediate annealing is performed after rolling, and the temperature is selected to be around the recrystallization temperature, so that the silicon particles hardly become coarse due to the intermediate annealing. After obtaining a bearing alloy of a predetermined thickness by casting and rolling (intermediate annealing) as described above, this is pressure-welded to a backing steel plate, and at this time, the temperature is lower than the temperature at which Al-Fe intermetallic compounds are formed, for example, 350°C. The conventional manufacturing method for aluminum alloy bearings containing tin and/or lead has been to press the bearings and then annealing them. this
Even at a temperature of 350° C., there was little coarsening of the silicon particles during normal holding times, with the result that fine silicon particles, mostly less than 5 microns, were present in the final bearing product. On the other hand, in order to have five or more coarse silicon particles of 5 microns to ⁴⁰ microns ^per 3.56 It has been found that the most effective method is to perform high-temperature heat treatment while adjusting the holding time. In other words, silicon particle size control in processes other than the heat treatment process before pressure welding is less effective; for example, controlling the heating temperature, rolling reduction rate, etc. in the rolling process, cooling rate control in the casting process, intermediate annealing, etc. It is extremely difficult to control the size of the particles, and heat treatment during and after pressure welding may result in the formation of Al-Fe intermetallic compounds, or the dissolution of low melting point components such as lead in the aluminum alloy of the bearing just before completion. occur, and these have undesirable consequences on bearing performance, especially on the familiarity of the general concept. Table 1 shows how the number of crystallized silicon particles changes depending on the silicon content in the high-temperature heat treatment before pressure bonding as described above. Table 1 was calculated assuming that all the silicon was crystallized as cubic silicon particles of the dimensions indicated in the horizontal columns. In reality, most of the silicon particles smaller than 5 microns are coarsened into silicon particles larger than 5 microns by high-temperature heat treatment before pressure bonding. Therefore, Table 1 is useful as a reference for the method of controlling silicon particles in the aluminum alloy of the present invention.

[Table] In the case of 0.5% silicon, the number of silicon particles is 340 from Table 1. Even if some of the silicon crystallizes as silicon particles smaller than 5 microns, it is easy to ensure 5 or more silicon particles. 5 micron silicon particles depend on silicon content
The number will be 340 to 3500 pieces. Although the number of silicon particles of 5 to 10 microns in actual bearing alloys is smaller than this, the ratio of coarse particles of 5 microns or more to fine particles of less than 5 microns is increased by high-temperature heat treatment before pressure welding. And for example 5~
350 to increase the proportion of coarse grain silicon to 10 microns
A pre-pressing high temperature heat treatment of ~450°C can be utilized. According to Table 1, the number of silicon particles when the silicon content is 3% is 4 if all the silicon is crystallized as particles of 40 microns. If this were made into one piece, it would be possible to crystallize both silicon particles of 5 to 30 microns and silicon particles of 40 microns. Therefore, it is possible to crystallize a specific number of coarser silicon particles within the silicon content range of the lead-containing aluminum alloy of the present invention and within the particle size range of 5 to 40 microns. Three preferred examples are as follows. (a) 5 or more silicon particles larger than 10 microns, (b) 2 or more silicon particles larger than 20 microns, (c) 1 or more silicon particles larger than 30 microns. Next, the morphology of the coarse silicon particles according to the present invention will be explained. Generally, silicon particles in rolled tin and/or lead-containing aluminum alloys are needle-shaped, and their longitudinal direction often coincides with the rolling direction, but when the high-temperature heat treatment of the present invention is applied, the silicon particles The width in the direction perpendicular to the rolling direction is relatively large and the shape is flat or lumpy. These silicon particles have a substantially lump-like shape when viewed from the horizontal plane of the bearing, that is, the plane in contact with the shaft of the mating material. The preferred shape is blocky in horizontal and vertical planes. Most of the silicon particles having a size of 5 microns or more are in the form of lumps, have few flat shapes, and have almost no needle shapes in a given area. Such a blocky shape is extremely effective in terms of special conforming effect. The structure of the aluminum-based alloy containing lead, etc. is observed on the above-mentioned horizontal plane, excluding the outermost surface that has been altered by machining, and the dimensions of the silicon particles are measured. In addition to silicon particles, intermetallic compounds of chromium, particles of lead, and other particles (phases) are present in this alloy, but in order to distinguish silicon particles from these, it is necessary to In some cases, chromium, lead, etc. are white, and silicon particles are gray (dark gray) regardless of the etching method. The present invention will be explained below using examples. In these Examples, unless otherwise specified, the method of manufacturing the bearing or bearing alloy was as follows. An aluminum alloy of a predetermined composition was continuously cast to form a plate with a thickness of 15 mm, and after peeling, the cast plate was continuously cold-rolled to a plate thickness of 6 mm. Then intermediate annealing
The aluminum alloy thin plate was obtained by cold rolling at 350°C and subsequent cold rolling. Next, high-temperature heat treatment is performed in the range of 350 to 550°C to obtain silicon particles of a desired size, and then the aluminum alloy thin plate is preheated to 100°C, pressure-welded to a similarly preheated back metal plate, and then heated to 350°C.
The bearing was completed by annealing for pressure welding. When testing the performance of the bearing alloy itself, the steps after pressure welding were omitted. Example 1 Table 2 shows the composition and silicon particle distribution of the aluminum alloy test material. Unless otherwise specified in the table or below, the number of silicon particles is 3.56×10 ^-2 mm ²
Indicates the number of hits.

[Table] The test materials in Table 2 were subjected to seizure load measurements under the following conditions. Conditions A Tester: Journal type seizure tester Conditions: Compatible shaft - FCD 70 Lubricating oil type - SAE10W - 30 Shaft surface roughness - 0.4 to 0.6μmRz Lubricating oil temperature - 140±2.5℃ Shaft rotation speed - 1000 rpm Shaft diameter - 52mm Shaft hardness - Hv 200-300 Load - 50Kg/cm ² Increased by the same amount at 30min intervals Bearing roughness - 1 to 1.8μmRz Bearing diameter - 52mm The seizure load measurement results are shown in Figure 1. In FIG. 1, the horizontal axis represents the number of silicon particles with the maximum size of the sample material. The test materials are divided into five groups, A through E, according to the maximum particle size of the five ranges in Table 1, and are shown in FIG. The following facts become clear from this figure. The seizure load depends on the maximum size of the silicon particles. That is, among groups A, B, C, D, and E, the latter has a higher seizure load. In addition, for groups other than group A, the seizure load increases with the number of silicon particles having the maximum size. For this reason, in the present invention, the number of silicon particles of at least 5 microns is limited to 5 or more. Thus, while the test materials of Group A, which are outside the scope of the present invention, have a seizure load of just under 500 kg/cm ² at most, the present invention can obtain a seizure load twice this amount. Example 2 Seizure load and fatigue strength were measured for the test materials shown in Table 3 (1). The conditions for measuring fatigue strength were as follows. Conditions B Tester: Alternating load tester Conditions: Mating material shaft - S55C Lubricating oil type - SAE10W - 30 Shaft surface roughness - 0.8μmRz Lubricating oil temperature - 140±2.5℃ Lubricating oil pressure - 5Kg/cm ^2- axis rotation speed - 3000rpm Shaft diameter - 52φ Shaft hardness - Hv 500 - 600 Number of shaft rotations - 10 ⁷ times Bearing roughness - 1 to 1.8 μmRz Bearing diameter - 52 x 20 mm The measurement results are shown in Table 3 (2). This shows that according to the present invention, the seizure load is improved and the fatigue strength is not deteriorated by coarse silicon particles. Note that in Table 3 (1), the number of silicon particles less than 5 microns was not measured. Furthermore, this mating material shaft is made of carbon steel for mechanical structures (S55C), and it can be seen that the bearing alloy according to the present invention is effective even when carbon in the mating material does not exist in the form of graphite.

【table】

【table】

[Table] Example 3 Example 2 for sample material with silicon content of 1%
When conducting a similar experiment, Table 4 (1) and (2)
Similar results were obtained as shown in .

【table】

【table】

[Table] Example 4 Table 5 (1) and (2) show the results of an experiment conducted in the same manner as in Example 2 using a sample material with a silicon content of 3%. This result is almost the same as in Example 2.

【table】

【table】

【table】

[Table] Example 5 Example 2 for the sample material with a silicon content of 4.7%
The results of experiments conducted in the same manner as above are shown in Table 6 (1) and (2). The experimental results are almost the same as in Example 2.

【table】

[Table] Example 6 The surface roughness of the spheroidal graphite cast iron shaft of the mating material was varied for sample material C3 of Example 1, and the seizure load was measured under condition A. The results are shown in FIG. As a comparative example (COMP), the seizure load of a 4% Sn-1% Cu-Al alloy was measured. From the figure, it is clear that the seizure load of the material of the present invention is good regardless of the surface roughness of the mating material. In addition, the comparative material has almost no crystallization of hard particles, and the compatibility of the general concept of a soft tin phase provides the aluminum alloy with seizure resistance. Therefore, from FIG. 2, it is possible to see the difference in the effects of the general concept and special conformability on seizure resistance. Furthermore, since the mating material is spheroidal graphite cast iron, it is well understood that the material of the present invention has high seizure resistance against spheroidal graphite cast iron. Example 7 Figure 3 shows the results of measuring the seizure load (condition A) when the silicon particle distribution was kept constant and the silicon content was varied as in the test materials shown in Table 7. The measured results (condition B) are shown in FIG. In addition, in FIG. 3, the plot of each test material listed in Table 6, which was tested three times, is shown as a curve.

[Table] From FIG. 3, it can be seen that the seizure load becomes maximum when the silicon content is about 3%. As mentioned above, the seizure load is controlled by the number and size of the maximum silicon particles in the silicon content range of the present invention, but in this example where the lower limit of the number of particles with a particle size of 5 microns is controlled constant, it is determined by the silicon content. Some influence can be seen. This is believed to be due to fine silicon particles of less than 5 microns. From FIG. 4, it can be seen that when the silicon content exceeds 5%, the fatigue strength decreases. This is also considered to be due to the fine particles mentioned above. Example 8 Experiments similar to Examples 2, 3, 4, and 5 were conducted by changing other types of lead, copper, etc. The results are shown in Table 8 (1) and (2). From these tables, it can be seen that sufficient seizure load and fatigue strength can be obtained with various arbitrary components.

【table】

【table】

[Table] Example 9 The following experiment was conducted using the test materials shown in Table 1. (1) Effect of lubricating oil temperature 80°C and 140°C under condition A for C3 test material
The seizure load was measured at an oil temperature of °C. Similar measurements were conducted using a 4%Sn-1%Cn-Al alloy as a sample material for comparison. The results are shown in FIG. It can be seen that there is an extreme difference in the seizure load at high temperatures between the comparative material and the material of the present invention. (2) Influence of mating materials (forged shaft and spheroidal graphite cast iron) at oil temperature of 140°C C3 specimen and 4%Sn-1%Cn-Al alloy were used as comparative specimens under condition A (however, oil temperature was 140°C). Fig. 6 shows the results of measuring the seizure load at 30°C. There is no significant difference in seizure load between the test materials of the present invention and comparative examples when the counterpart material is a forged material, but an extreme difference appears in the case of spheroidal graphite cast iron (FCD70). (3) Wear resistance A wear resistance test was conducted on the C3 sample material under the following conditions. Conditions C Tester: Mixed lubrication tester Conditions: Mating material shaft - FCD 70 Shaft surface roughness - 0.8~0.9μmRz Lubricating oil type - Liquid paraffin Shaft rotation speed - 100rpm Shaft diameter - 40φ (mm) Shaft strength - Hv 200~ 300 Load - 25Kg For comparison, 4% Sn-1 which does not contain silicon
The amount of wear of the %Cn-Al alloy was measured under Condition C. The wear amount measurement results are shown in Fig. 7. The comparative material (COMP) wears out progressively over time, but the material of the present invention shows almost no increase in wear amount after about one hour. The inventor thinks about such a difference as follows. In the material of the present invention, the coarse silicon particles present on the bearing surface wear out the protrusions of the surface roughness of the mating shaft and the edges such as burrs around the spherical graphite present on the surface at the initial stage of sliding. By scraping the surface of the shaft and changing it into a shaft surface that provides a better sliding condition for the bearing, it creates a state close to fluid lubrication and prevents direct contact between the shaft and the bearing, which stops the progress of bearing wear. It is assumed that Example 10 (comparative example) After cold rolling an aluminum alloy containing 4% Sn, 3% Pb, 0.5% Cu, 0.4% Cr and with varying silicon content, annealing of the cold rolled plate was omitted. Other than that, a bearing was manufactured using the same manufacturing method as the test material of the present invention (COMP). Fig. 8 shows the results of measuring the seizure load for each three specimens under condition A. Comparing the same silicon content of less than 5% in Figure 8 and Figure 3, which show the seizure load of the test material without coarsening the silicon particles, the test material of the present invention has a significantly higher seizure load. It can also be seen that the variation in seizure load is reduced. The results of measuring the wear amount of the comparative materials and the test materials 33 to 38 (Example 7) of the present invention under condition C are shown in the ninth table.
As shown in the figure. From this drawing, it can be seen that the wear resistance of lead-containing aluminum alloys is significantly improved when the silicon particle size is controlled by performing high-temperature heat treatment according to the present invention. Example 11 The microscopic structure of an aluminum alloy containing 3% Si, 4% Pb, 0.5% Cu, and 0.4% Cr on a horizontal plane was observed while changing the annealing temperature before pressure welding as follows. 200℃ (comparative example low temperature heat treatment) 400℃ 480℃ 530℃ heating and slow cooling In the structure of the comparative example, most of the silicon particles are 5
Although there are some silicon particles with a size of less than a micron and a size of 5 microns or more, they have an acicular or flat shape extending in the rolling direction. This is an example in which the size of silicon particles was controlled to 5 to 10 microns at 400°C. Comparing the comparative example and 400℃, fine silicon particles of less than 5 microns are
At 400°C, the number decreases, and coarse and lumpy silicon particles of 5 microns or more are observed. From this fact, it is inferred that the high temperature heat treatment of the present invention causes fine silicon particles to coalesce and turn into coarse particles. 400
℃ more than 10 microns and less than 20 microns, 480℃
The size of the silicon particles was controlled to exceed 20 microns and below 30 microns. In addition to bulky silicon crystals, elongated Pb alloy particles were observed. Comparing 480°C and 530°C, it was found that the Pb alloy particles became coarser due to the higher temperature heat treatment. A sketch of silicon and lead particles at 530°C is shown in Figure 10. Since the Pb alloy particles have an irregular shape and the silicon particles have a regular shape such as a polygon, the behavior of the former during high-temperature heat treatment is clearly different from the behavior of the latter. Here, since Pb alloy particles have a low melting point, it can be expected to some extent from general knowledge of tin (lead)-containing metal materials that the shape will change due to melting and softening. However, it is difficult to provide a theoretically valid explanation for the coalescence of silicon particles and the resulting agglomeration. In any case, it is a discovery of the present invention that an aluminum alloy structure containing bulky coarse silicon particles improves bearing performance, and the present invention has great industrial significance as it significantly improves bearing performance.

[Brief explanation of the drawing]

Figure 1 is a graph showing the relationship between seizure load and the number of maximum size silicon particles, Figure 2 is a graph showing the relationship between seizure load and shaft surface roughness, and Figure 3 is a graph showing the relationship between seizure load and silicon content. Figure 4 is a graph showing the relationship between fatigue strength and silicon content, Figure 5 is a graph showing the relationship between seizure load and lubricating oil temperature, and Figure 6 is a graph showing the relationship between seizure load and lubricating oil temperature.
The figure shows the change in seizure load depending on the type of mating shaft, Figure 7 is a graph showing the change in wear amount over time, Figure 8 is a graph showing the relationship between seizure load and silicon content, and Figure 9 is the wear amount. Figure 10 is a graph showing the relationship between silicon content and silicon content. In the drawing, COMP refers to the comparative material, and other numbers and symbols refer to the numbers of the sample materials.

Claims (1)

[Scope of Claims] 1 Contains at least one member selected from the group consisting of lead, cadmium, indium, thallium, and bismuth in a weight percentage of 0.1 to 10%, and silicon in a weight percentage of 0.5 to less than 5%, with the remainder being substantially An alloy made of aluminum is adhered to a backing metal, and the silicon particles in the aluminum alloy having a dimension of 5 microns or more and 40 microns or less as measured by the major axis of silicon are 3.56 x 10 ^- in any part of the alloy. ²
Aluminum alloy bearings that have 5 or more pieces per mm ² and can be used without an overlay. 2 Silicon particles with dimensions of 10 microns or more and 40 microns or less in any part of the alloy 3.56
The aluminum alloy bearing according to claim 1, wherein there are two or more bearings per 10 ^-2 mm ² . 3. Claim 1, wherein the content of at least one element of the group consisting of lead, cadmium, indium, thallium, and bismuth is 1 to 6%, and the content of silicon is 2% or more and less than 5%. Alloy bearings listed in section. 4. The aluminum-based alloy bearing according to any one of claims 1 to 3, wherein the shaft of the bearing mating material is made of spheroidal graphite cast iron or flake graphite cast iron. 5. The aluminum-based alloy bearing according to claim 4, wherein the silicon particles having a particle size of 55 to 40 microns are in the form of a block when viewed in a horizontal plane, that is, a plane parallel to the plane in contact with the axis of the mating material. 6 At least one member selected from the group consisting of lead, cadmium, indium, thallium, and bismuth in a weight percentage of 0.1 to 10%, at least one member selected from the group consisting of copper and magnesium in a weight percentage of 0.1 to 2%, and An alloy containing 0.5 to less than 5% silicon, the remainder being substantially aluminum, is adhered to a backing metal, and the silicon particles in the aluminum alloy have a size of 5 microns or more and 40 microns or less, as measured by the major axis of the silicon particles. An aluminum-based alloy bearing in which 5 or more silicon particles are present per 3.56×10 ^-2 mm ² in any part of the alloy, and which can be used without an overlay. 7. At least one member selected from the group consisting of chromium and manganese in an amount of 0.1 to 1% by weight.
The backing metal is an alloy containing 0.1 to 10% of at least one selected from the group consisting of lead, cadmium, indium, thallium, and bismuth, and 0.5 to less than 5% of silicon, the balance being substantially aluminum. 5 or more silicon particles per 3.56 x 10 ^-2 mm ² in any part of the aluminum alloy with a dimension of 5 microns or more and 40 microns or less as measured by the long axis of the silicon particles in the aluminum alloy Aluminum alloy bearings that exist and can be used without overlays. 8. At least one member selected from the group consisting of chromium and manganese in an amount of 0.1 to 1% by weight.
0.1 to 10% of lead, cadmium, indium, thallium, and bismuth, 0.1 to 2% of copper, and at least one selected from the group of magnesium, and 0.5 to 5% of copper. % of silicon, the remainder being substantially aluminum, is adhered to a backing metal, and the silicon particles in the aluminum alloy have a size of 5 microns or more and 40 microns or less, as measured by the major axis of the silicon particles in the aluminum alloy. An aluminum-based alloy bearing in which 5 or more silicon particles are present per 3.56×10 ^-2 mm ² in any part of the alloy, and which can be used without an overlay.