JPS6212297B2 - - 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 surface of the bearing that is designed to ensure that the bearing and shaft always come into 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 add a metal harder than tin or lead to the aluminum alloy to strengthen the aluminum base and improve bearing performance. 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 Al, 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 in addition, it has become necessary to install blow-by gas reduction devices to purify exhaust gas. It got even worse. 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 move, which is the cause of the decrease in fatigue strength. The inventor of the present application believes that this has become the case. 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 1.0% chromium by weight percentage. In addition, the applicant of the present application has stated in Japanese Patent Application No. 1985-852 that the weight percentage is 2.5 to 25%.
of tin, 0.5 to 8% zinc and 1 to 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 most of the zinc is dissolved in the matrix and strengthens 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 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, regarding the effects of chromium, silicon, etc., these particles
In other words, there is no technical idea that particles such as chromium, silicon, etc. directly improve compatibility, but by controlling the morphology of soft tin and/or lead particles. It can be said that the description of the above patent application is consistent with the technical idea of indirectly improving the conformability of tin and/or lead-containing aluminum alloys and the technical means described below. 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 will be described in detail later, this technical means is to control the size of hard particles in tin-containing aluminum alloys, but in Si-Al = elemental alloys, hard particles precipitate or crystallize (hereinafter referred to as crystallization for convenience). ) is a well-known fact, and papers and patents discussing the distribution of silicon particles in aluminum-based bearing alloys for internal combustion engines have also been published. 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 that coarse silicon particles in a cast state are finely dispersed by rolling or the like, and the annealing performed as necessary after rolling is limited to the extent that the processed structure is restored, thereby maintaining the fine morphology of the silicon particles. 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, if the content of hard particle crystallized elements such as silicon is high, the fatigue strength of the bearings decreases.
It has been found that there is a drawback in that the load capacity is significantly reduced especially when the bearing slides under repeated loads from the shaft. Furthermore, for the purpose of improving bearing performance, methods such as rolling that finely disperse silicon particles do not provide satisfactory results. That is, aluminum alloys for bearings are usually manufactured by giving a cast material a predetermined size by a method such as rolling, and the silicon particles are divided by this rolling or the like. It has been found that bearing performance can be significantly improved by not only dividing these hard particles such as silicon, but also by making these particles coarser in some cases and controlling the number of hard particles with a given size to a given number. .
By the way, in the above publication, an experiment was conducted on an aluminum alloy containing 11% silicon, and it is stated that the size of silicon fine particles is 0.0001 inch (2.5 microns) to 0.001 inch (25 microns), but the size per unit area is There is no mention of the number. Aluminum from SAE Technical Paper Series
Based Crankshaft Beasings for the High
Paper entitled Speed Diesel Engine (February 1981)
23rd-27th, Detroit) is a paper published by the same person as the above publication, and 11% of the papers were published by the same person as the above publication.
The seizure load for Si-1%Cu-Al alloy is listed. According to this, silicon particles with a size exceeding 17 microns have a density of 8.7 microns per unit area (mm ² ).
It is explained that if there are 6 × 10 ⁶ particles, there will be a lot of variation in the seizure load, while if there are 0.6 × 10 ⁶ 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. Furthermore, in the above paper, the concept of ``adaptability'' is contradictory to the concept of ``compatibility,'' which refers to the concept of ``adaptability,'' which allows for misalignment between the crankshaft and the shaft.
It is stated that since silicon-containing aluminum alloys have low conformability, it is necessary to provide an overlay. 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 therefore 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 well-known theory. 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 one element of the first group consisting of 0.1 to 10% lead, cadmium, indium, thallium, and bismuth, and 0.5 to 11% manganese, iron, An alloy containing at least one element of a second group consisting of zirconium, titanium, antimony, nickel, molybdenum, cobalt, chromium, and niobium, the remainder being substantially aluminum, is adhered to the back metal; There are 5 or more particles per 3.56 x 10 ^-2 mm ² in any part of the alloy, and the size of the particles is 5 microns or more and 40 microns as measured by the major axis of the particles consisting of or containing elements of the group, and This is an aluminum alloy bearing that can be used without an overlay. Hereinafter, the constituent elements of the present invention will be explained in the order of chemical composition, particles, and bearing structure. First, regarding the chemical composition, lead, cadmium, indium, thallium, and bismuth (hereinafter referred to as lead, etc. when referring to all of these elements) change the properties of the aluminum alloy to soft, and improve the lubricating performance and properties suitable for bearings. It is an element that provides familiarity. 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. When the content of lead, etc. exceeds 10%, the general concept of conformability and lubricity improves, but the hardness of the aluminum alloy decreases, and the content of lead, etc.
If it is less than 0.1%, the aluminum alloy becomes too hard as a bearing alloy, and the general concept's compatibility deteriorates. How to determine the content of lead, etc. in the range of 0.1 to 10% should be determined appropriately depending on the application, but in general, it is determined based on the load applied to the bearing, that is, through the piston of the internal combustion engine. When the explosive load applied is large, the content should be low, for example 1 to 4%, and when it is small, the content of lead etc. should be high. On the other hand, if the bearing is likely to seize 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 the bearing as a bearing for an internal combustion engine even if miniaturization of tin particles is not so important. The preferred content of lead etc. is 1~
It is 6%. Manganese, iron, molybdenum, nickel, zirconium, titanium, cobalt, antimony, chromium, and niobium (hereinafter collectively referred to as manganese, etc.) are elements that bring about the special conforming effect described below, and their content is less than 0.5%. If the content exceeds 11%, the breaking-in effect of the bearing alloy will not be improved, and the fatigue strength and seizure load will tend to decrease.The preferred content of manganese, etc. is 1 to 9%. be. When two or more elements are added, the lower limit of each element is preferably 0.1%. Next, particles generated by adding manganese or the like will be explained. Manganese and the like crystallize either in the form of a single metal or in the form of an intermetallic compound of manganese and aluminum, and it is not possible to analyze the components of the crystallized product. However, by adding manganese or the like to an aluminum alloy containing lead or the like, hard particles other than soft particles such as lead crystallize. Therefore, particles consisting of or containing manganese etc. are crystallized, and these are hereinafter referred to as hard particles. According to the findings of the present inventors, a special running-in effect that does not appear when the major axis dimension (hereinafter simply referred to as the dimension) of the hard particles is less than 5 microns appears when it is 5 microns or more, which dramatically improves the bearing performance of aluminum alloys containing lead, etc. . This effect is observed when 5 or more hard 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, when the size of the hard particles exceeds 40 microns, the fatigue strength of the aluminum alloy containing lead etc. decreases. From this point of view, the upper limit of the content of manganese, etc. in the alloy of the present invention is 11% as described above. In addition, the significance of specifying coarse hard particles, that is, hard particles with a size of 5 microns or more as a component in the present invention, is that, in a negative sense, fine hard particles do not contribute to improving bearing performance. In this respect, it differs from the conventional approach to understanding the bearing performance of aluminum-based alloy bearings. In other words, in the applicant's previous application, fine silicon particles indirectly improve bearing performance through the control of the shape of tin particles, as mentioned above, and in the above-mentioned SAE journal paper, both theoretically and experimental data However, finer silicon particles provide better bearing performance. However, in the present invention, coarse hard particles have much better performance other than fatigue strength. Therefore, if we were to actively discuss the significance of coarse hard 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 hard particles, or by lapping of the surface when the shaft is made of spheroidal graphite cast iron. It is thought that the hard particles flatten the periphery of the recesses created by more graphite falling off, and that good sliding occurs between the bearing and the shaft with an oil film always present.
In addition, in the field of conventional bearings, it is common to think that hard components such as tin contribute to the conformability of aluminum alloys, and the idea that hard particles directly contribute to flattening the unevenness of the mating material is As far as the inventors know, there is no such thing other than the above-mentioned SAE magazine, so the conforming effect by hard particles is referred to as a special conforming effect. However, this effect of silicon particles is considered by SAE to improve flexibility,
Compatibility is adversely affected, and as a result it is emphasized that the bearing must be provided with 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. There has also been no published experimental data showing that bearing performance such as seizure load is improved when a large amount of is present in a bearing. 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 hard 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 an automobile internal combustion engine. 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 hard aluminum matrix is scraped off by the burr and incorporated into the recess, and this aluminum and the bearing material's lack of conformability make it very easy to stick together, resulting in seizure immediately. It also became clear that However, in the lead-containing aluminum alloy according to the present invention, the coarse hard 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. The bearing alloy is bonded with or without an underlayer by a method such as pressure welding. The lead-containing aluminum alloy of the present invention has (A) 0.1
It may further contain at least one of copper and magnesium (hereinafter referred to as copper, etc.) in an amount of 2% to 2%, preferably 0.2 to 1%. Copper and the like increase the high-temperature hardness of tin-containing aluminum alloys and contribute to improving the fatigue strength of bearings. If the content of copper, etc. is less than 0.1%, the effect of improving high-temperature hardness will be small, and if it exceeds 2.0%, the aluminum alloy containing lead, etc. will become too hard, impairing rolling properties, and will also reduce seizure resistance and corrosion resistance to lubricating oil. . The high-temperature hardness improvement effect of copper, etc. becomes even more pronounced when it coexists with chromium, and the hardness does not decrease much even at temperatures above 200°C. If less than 0.5% of manganese and/or chromium is contained, or if some manganese and/or chromium does not form coarse hard particles, the manganese and/or chromium will form fine precipitates. Manganese and chromium, which precipitate as fine precipitates, increase the hardness of aluminum-based alloys containing lead, etc., and also prevent or reduce softening at high temperatures, and have the effect of not causing coarsening of lead, etc. particles at high temperatures. play. Some of the chromium and manganese dissolve in solid solution in the aluminum base, resulting in solid solution strengthening.
In addition, the recrystallization softening temperature is shifted to a higher temperature side, and work hardenability is further increased. An increase in the recrystallization softening temperature means that the high-temperature strength of the bearing alloy is maintained well even in the high-temperature range to which internal combustion engine bearings are exposed (oil pan temperature of 130 to 150 degrees Celsius), resulting in improved fatigue resistance and load resistance. Achieves desired results in terms of performance. The portions of chromium and manganese that are not solidly dissolved in the aluminum matrix precipitate extremely finely as Al-Cr (Mn) intermetallic compounds, and particles such as lead are formed during annealing when bonding the bearing alloy to the backing metal or at high temperatures in internal combustion engines. This prevents it from becoming coarser. This Al-Cr
The hardness of (Mn) intermetallic compounds is approximately the Bitkers hardness.
370, which is significantly smaller than the hardness of hard particles. Because of this difference in hardness, Al-Cr
(Mn) intermetallic compounds are thought to prevent coarsening of particles such as lead and improve the general conforming effect, while hard particles flatten the unevenness of the shaft of the mating material and achieve a special conforming effect. It will be done. A content of 0.1% is required to provide the benefits of chromium and manganese as described above. Next, a method for controlling the size and number of hard particles will be explained. Judging from the phase diagram of binary alloys such as Al-Mn, the hard particles are thought to be of the following types depending on the type of alloying element. Mn:MnAl ₄ and MnAl ₆ Fe:FeAl ₃ Mo:MoAl ₃ Ni:NiAl ₃ Zr:ZrAl ₃ Co:Co ₂ Al ₉ Ti:TiAl ₃ Sb:AlSb Nb:NbAl _3The above intermetallic compounds are considered to be present during casting. The forms of crystallization are diverse, and these crystallized substances are broken up and reduced in size during the process of rolling the cast alloy to the required thickness for the bearing. Casting like this
Most of the hard particles obtained by the rolling method are 5 microns or less, and although some are rarely 10 microns or less, their number per unit area is small and they are acicular or flat. Further, intermediate annealing is performed after rolling, and the temperature is selected to be approximately the recrystallization temperature, so that the hard 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.
The conventional method for manufacturing tin- and/or lead-containing aluminum alloy bearings has been to perform annealing after pressure welding at a temperature below the intermetallic compound formation temperature, for example, 350°C. Even at this temperature of 350°C, the hard particles hardly became coarse during the normal holding time, and as a result, fine hard particles, most of which were less than 5 microns, were present in the final bearing product. On the other hand, the phase-large hard particles according to the present invention have a diameter of 5 microns or more and 40 microns or less.
In order to have more than 5 pieces per 3.56×10 ^-2 mm ² ,
It has been found that it is most effective to subject the bearing alloy to high-temperature heat treatment at 350 to 550° C. by adjusting the holding time before the above-mentioned pressure welding. In other words, controlling the hard particle size in a process 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 because of this, Al-
The formation of Fe intermetallic compounds or the dissolution of low melting point components such as lead in the aluminum alloy of the bearing immediately before completion occur, and these have undesirable consequences in terms of bearing performance, especially in terms of general concept compatibility. Table 1 shows how the approximate number of crystallized hard particles changes depending on the content of manganese etc. in the high-temperature heat treatment before pressure bonding as described above. Table 1 is calculated assuming that all manganese etc. are crystallized as cubic hard particles having the dimensions shown in the horizontal column. In reality, most of the hard particles smaller than 5 microns are coarsened into hard particles larger than 5 microns by high-temperature heat treatment before pressure bonding. Therefore, Table 1 is useful as a material for controlling hard particles in the aluminum alloy of the present invention.

[Table] When the content of manganese etc. is 0.5%, the number of hard particles is 340 from Table 1. Even if a part of manganese etc. crystallizes as hard particles of less than 5 microns, it is easy to secure 5 or more particles. The number of 5 micron hard particles is 340 to 3500 depending on the content of manganese etc. Although the number of hard 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. For example, in order to increase the proportion of coarse hard particles of 5 to 10 microns, high-temperature heat treatment at 350 to 450° C. can be used before pressure welding. According to Table 1, the number of hard particles when the content of manganese, etc. is 3% is 4, if manganese, etc. is completely crystallized as particles of 40 microns. If this number is one, it is possible to crystallize both 5 to 30 micron hard particles and 40 micron hard particles. Therefore, it is possible to precipitate a specific number of coarser hard particles within the range of the content of manganese, etc. in the lead-containing aluminum alloy of the present invention, and within the size range of 5 to 40 microns. A preferred example of this is as follows. (a) 5 or more hard particles of 10 microns or more (b) 2 or more hard particles of 20 microns or more (c) 1 or more hard particles of 30 microns or more Next, the morphology of the hard particles according to the present invention will be explained. Generally, hard particles in rolled aluminum alloys containing lead, etc. exhibit a needle shape, and the longitudinal direction often coincides with the rolling direction, but when the high temperature heat treatment of the present invention is performed, the hard particles have a relatively narrow width in the direction perpendicular to the rolling direction. becomes large and flat or lumpy. These hard particles have a flat or block shape when viewed from the horizontal surface of the bearing, that is, the surface in contact with the shaft of the mating material. A preferred shape is block-like when viewed in a horizontal plane and in a plane perpendicular thereto.
Most of the hard particles having a diameter 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. Furthermore, as a method for observing the structure of an aluminum-based alloy containing lead, etc., the dimensions of the hard particles are measured on the above-mentioned horizontal plane, excluding the mechanically altered outermost surface. In the examples described below, a PMG type universal metallurgical microscope (equipped with a dry plate photographing device) manufactured by Olympus Optical Industries, Ltd. is used to examine the structure of the alloy on a hand plate type process film (manufactured by Fuji Photo Film Co., Ltd.). was photographed. Since there is a lot of disturbance in focus and image around the photographic field of view, the area of 89 x 64 mm ² excluding the peripheral area =
The number of particles was measured for 3.56×10 ⁻² mm. According to such a counting method, there is no need to convert the measurement visual field area each time, and conversion errors are eliminated. In addition to hard particles, the alloy contains metal compounds of chromium, particles of lead, and other particles (phases). Regardless of the method, it is sufficient to rely on the fact that lead, chromium, etc. exhibit a white color, and hard particles exhibit a gray (dark gray) color. The present invention will be explained below using examples. In these Examples, unless otherwise specified, the manufacturing method of 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. Next, intermediate annealing (350°C) was performed, followed by cold rolling to obtain an aluminum alloy thin plate. Subsequently, high temperature heat treatment is performed in the range of 350 to 550°C to obtain hard particles of the desired size, and then the aluminum alloy thin plate is preheated to 230°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 hard particle distribution of the aluminum alloy test material. Unless otherwise specified in the table and below, the number of hard particles refers to the number per 3.56×10 ⁻² mm ² .

[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 - FCD70 Lubricating oil type - SAE10W - 30 Shaft surface roughness - 0.6 to 0.8μm Rz Lubricating oil temperature - 160±2.5℃ Shaft rotation speed - 1000rpm Shaft diameter - 52mm Shaft hardness - Hv200 - 300 Load - 50Kg/cm ² Increased by the same amount at 30min intervals Bearing roughness - 1 to 1.8μm Rz Bearing diameter - 52mm The seizure load measurement results are shown in Figure 1. In FIG. 1, the horizontal axis represents the number of maximum dimension hard particles of the sample material. The test materials were divided into four groups from A to D according to the maximum particle size in the four ranges shown in Table 1.
It is shown in FIG. The following facts become clear from this figure. (a) The seizure load is influenced by the number of manganese particles with the largest size, and is almost unaffected by the number of hard particles with smaller sizes. (b) The seizure load increases with the number of hard particles of maximum size. However, there is almost no increase in the seizure load for the test materials of Group A, and there is a significant increase in the seizure load for the other groups containing hard particles with larger dimensions. Based on the above facts (a) and (b), the present invention is limited to having at least 5 hard particles of at least 5 microns. 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 - 0.8μm Rz Lubricating oil temperature - 140±2.5℃ Lubricating oil pressure - 5Kg/cm ^2- axis rotation speed - 3000rpm Shaft diameter - 52φ Shaft hardness - Hv500 - 600 Number of shaft rotations - 10 ⁷ times Bearing roughness - 1 to 1.8μm Rz Bearing diameter - 52 x 20mm

[Table] The measurement results are shown in Table 3 (2). From this, it can be seen that according to the present invention, the seizure load is improved and the fatigue strength is not deteriorated by coarse hard particles. In addition,
In Table 3 (1), the number of hard particles less than 5 microns was not measured. Furthermore, the material to be used in the fatigue test was carbon steel for machine structures (S55C), and it can be seen that the material of the present invention is effective even when carbon does not exist in the form of graphite in the ferrous material.

【table】

[Table] Example 3 When the same experiment as in Example 2 was conducted on a sample material with a manganese content of 7%, Table 4 (1) and
Similar results were obtained as shown in (2).

【table】

【table】

[Table] Example 4 Example 2 for a test material with a manganese content of 11%
The results of experiments conducted in the same manner as above are shown in Tables 5 (1) and (2). The experimental results are almost the same as in Example 2.

【table】

[Table] Example 5 The results of measuring the seizure load (condition A) when the hard particle distribution was kept constant and the contents of all elements such as manganese were varied as in the test materials shown in Table 6 are shown below. It is shown in Figure 2. In addition, in Figure 2, 4
A comparative example (COMP) of an aluminum alloy containing % Pb, 0.5% Cu, 0.4% Cr, Mn, etc. was annealed at 350°C before pressure welding, and the hard particle size was not controlled. From FIG. 2, it can be seen that the test material of the present invention has a significantly higher seizure load than that of the comparative example. Further, in the sample material of the present invention, the seizure load is saturated at about 4% manganese etc. As mentioned above, the seizure load is controlled by the number and size of the maximum hard particles in the content range of manganese, etc. of the present invention, but in this example, where the number of particles with a lower limit of 5 microns was controlled to be constant, manganese, etc. Some influence can be seen depending on the content of This is thought to be due to fine hard particles of less than 5 microns. The results of measuring the fatigue strength of the test material of the present invention under condition B are shown in FIG. From FIG. 3, it can be seen that when the content of manganese etc. exceeds 5%, the fatigue strength decreases. This is also considered to be due to the fine particles mentioned above.

[Table] Example 6 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 7 (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] Figure 10 shows a microscopic structure photograph of sample material 44 (magnification
400x). Low melting point metals such as Pb have an amorphous structure and are somewhat elongated in the rolling direction. on the other hand
Cr is hard and has flaky, spherical, and polygonal particle shapes. Therefore, Pb etc. and Cr can be easily distinguished. Example 7 The following experiment was conducted using the test materials shown in Table 2. ( ₁ ) Influence of lubricating oil temperature
The seizure load was measured at an oil temperature of 140°C. Similar measurements were conducted using a 4% Pb-1% Cu-Al alloy as a comparative material (COMP). 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 _C2 specimen and 20%Sn-1%Cu-Al alloy were used as comparison specimens, and condition A (oil temperature Figure 5 shows the results of measuring the seizure load at 140°C. There is no significant difference in seizure load between the test materials of the present invention and comparative examples when the mating material is a forged material, but a considerable difference appears when using spheroidal graphite cast iron (FCD70). (3) Wear resistance The amount of wear was measured for the _C2 test material under the following conditions. Conditions C Tester: Mixed lubrication tester Conditions: Mating material shaft - FCD70 Shaft surface roughness - 0.8 to 0.9μm Rz Lubricating oil type - Liquid paraffin Shaft rotation speed - 100rpm Shaft diameter - 40φ (mm) Shaft hardness - Hv200 to 300 Load: 25Kg For comparison, 6%Pb does not contain manganese etc.
- The amount of wear of the 1% Cu-Al alloy was measured under Condition C. The wear amount measurement results are shown in Figure 6. 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 comparative material, the soft lead phase is mainly scraped off by the shaft of the mating material, and as a result, the comparative material is constantly worn. In the material of the present invention, the coarse hard particles existing on the bearing surface wear out (scrape off) the protruding parts of the surface roughness of the mating shaft and the edges such as burrs around the spherical graphite existing on the surface at the initial stage of sliding. ), by changing the shaft surface to provide better sliding conditions when the shaft is attached to 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 there are. Example 8 A test sample of the present invention, except that annealing of the cold-rolled plate after cold-rolling an aluminum alloy containing 4% Pb, 0.5% Cu, and 0.4% Cr and varying the manganese content was omitted. The bearing was manufactured using the same manufacturing method as the material. The wear amount of this bearing was measured under condition G and the results are shown as (COMP) in FIG. The figure also shows the amount of wear of the specimens with sample numbers 25-33. Conditions G Tester: Mixed lubrication tester Conditions: Mating material shaft - FCD70 Shaft surface roughness - 0.8 to 0.9μm Rz Lubricating oil type - Liquid paraffin Shaft rotation speed - 100rpm Shaft diameter - 40φ (mm) Shaft hardness - Hv200 to 300 Load: 25Kg Test time: 5Hrs From FIG. 7, it can be seen that the wear resistance of aluminum alloys containing lead, etc. is significantly improved by performing high-temperature heat treatment according to the present invention and controlling the particle size of manganese, etc. Example 9 Horizontal plane microscopic structure sketches when the annealing temperature before pressure welding of an aluminum alloy containing 5% Mn, 4% Pb, 0.5% Cu, and 0.4% Cr is changed as follows are shown in each drawing. . 270°C (low-temperature heat treatment in comparative example) Fig. 8 Slow cooling after heating at 500°C Fig. 9 Hard particles change from flat to lumpy due to the high-temperature heat treatment of the present invention.

[Brief explanation of the drawing]

Figure 1 is a graph showing the relationship between seizure load and the number of maximum size manganese particles, Figure 2 is a graph showing the relationship between seizure load and manganese content, and Figure 3 is the relationship between fatigue strength and manganese content. A graph showing,
Figure 4 is a graph showing the relationship between seizure load and lubricating oil temperature, Figure 5 is a graph showing changes in seizure load depending on the type of mating shaft, Figure 6 is a graph showing changes in wear amount over time, and Figure 7 is a graph showing the change in wear amount over time. Amount of wear and manganese content (comparison material)
and manganese etc. content (sample material of the present invention), Figures 8 and 9 are sketch diagrams of the microscopic structure of the aluminum alloy specimen, and Figure 10 is a photograph of the metallographic microstructure of specimen material 44. It is. In the drawing, COMP refers to the comparative material, and other numbers and symbols refer to the numbers of the sample materials.

Claims (1)

[Claims] 1. At least one element of the first group consisting of lead, cadmium, indium, thallium and bismuth in a weight percentage of 0.1 to 10%, and 0.5 to 11% of manganese, iron, zirconium, titanium. ,
antimony, nickel, molybdenum, cobalt,
At least one of the second group consisting of chromium and niobium
An alloy containing a seed element and the remainder being substantially aluminum is adhered to the backing metal, and the second
There are 5 or more particles per 3.56 x 10 ^-2 mm ² in any part of the alloy, the size of which is 5 microns or more and 40 microns or less as measured by the major axis of particles consisting of or containing elements of the group, An aluminum alloy bearing that can be used without an overlay. 2 Particles consisting of or containing the elements of the second group having a size of 10 microns or more and 40 microns or less are present in any part of the alloy in 5 or more particles per 3.56 × 10 ^-2 mm ² An aluminum alloy bearing according to claim 1. 3. The aluminum alloy according to claim 1 or 2, wherein the content of the first group of elements is 1 to 6%, and the content of the second group of elements is 1 to 9%. bearing. 4. The aluminum 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 particles having a particle size of 55 microns to 40 microns are in the form of a lump 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 element of the first group consisting of lead, cadmium, indium, thallium and bismuth, 0.1 to 10% by weight, 0.5 to 11
% manganese, iron, zirconium, titanium, antimony, nickel, molybdenum, cobalt, chromium and niobium, and at least one element of the third group consisting of 0.1 to 2% copper and magnesium. Contains the elements of
An alloy, the remainder of which consists essentially of aluminum, is adhered to the back metal, and the particles of the alloy are made of or contain an element of the second group and have a dimension measured by the major axis of 5 microns or more and 40 microns or less. Aluminum alloy bearings that have 5 or more bearings per 3.56×10 ^-2 mm ² in any part and can be used without an overlay.