JPH0114990B2 - - Google Patents

Description

[Detailed description of the invention]

(1) Technical Field The present invention relates to a method for manufacturing an aluminum alloy bearing, and more specifically, to a manufacturing method that can improve the performance of a tin-containing aluminum alloy bearing used as a bearing for an internal combustion engine. (2) Description of Background Art The above 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, and 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. do not have. However, since tin and lead have common physical properties, aluminum alloy bearings containing lead in addition to tin to improve conformability are also used. Compatibility here means that the surface of the bearing is such that the surface of the bearing can always come into contact with the shaft with a lubricating oil film interposed between the bearing and the shaft, depending on 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 by the shaft during early use. (3-1) Description of the prior art (Part 1 - Description of alloy materials) The conventional method was 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. Accordingly, recent technology has led to proposals to strengthen the aluminum matrix and improve bearing performance by adding a metal harder than tin or lead to the aluminum alloy. In Japanese Patent Application No. 1985-851, the applicant 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, in Japanese Patent Application No. 1985-852, stated that in terms of weight percentage, 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, chromium etc. are dispersed in the matrix as extremely fine hard Al-Cr intermetallic compounds, which mainly have the effect of preventing the coarsening of tin particles, and most of the zinc is solidified in the matrix. The melting strengthens the matrix, thereby increasing the fatigue strength and high temperature hardness of the alloy. 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 concept in the industry, and the idea of imparting compatibility to bearings using soft tin and/or lead particles is in line with the conventional thinking in the industry. , and can be said to be an extension of that. In addition, the effects of chromium, silicon, etc. are understood from the perspective that these finely dispersed particles prevent the coarsening of tin and/or lead particles, so to speak, the particles of chromium, silicon, etc. directly improve compatibility. The description in the above patent application is based on the technical idea of indirectly improving the compatibility of tin and/or lead-containing aluminum alloys by controlling the morphology of soft tin and/or lead particles. It can be said that it is consistent. (3-2) Description of conventional technology (Part 2 - Description of bearing manufacturing method) According to Japanese Patent Application Laid-open No. 55-82756, in the manufacture of bearing alloys, 5 to 15% silicon, less than 5% copper, and 10% bismuth are used. A reduction in area of at least 90% is obtained by hot or cold rolling or extrusion of an aluminum-based alloy consisting of: An invention has been proposed in which the particles do not form a skeleton-like network structure but instead exist in the state of finely divided particles. The key point of this invention is that the relatively coarse silicon particles in the cast state are finely dispersed by rolling, etc., 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. be. Furthermore, since this invention specifies that a high silicon content of about 10% is preferable, it has been found to be meaningful to finely disperse silicon particles, which grow quite large in aluminum alloys with a high silicon content. There is. For example, US Patent No. 3078563, 3093885, 3104135,
The process for producing aluminum-based bearing alloys known as 3167404, 3300836, 3300838 and 3384950 involves melting aluminum in a gas furnace and adding the desired amount of Si and depending on the desired properties of the alloy by melting in a conventional manner. Aluminum with Pb, Sn,
It is prepared by adding desired amounts of Cu, Mg, Mn and/or Cr. The molten alloy is cast, and the cast alloy is subjected to skin shaving and, if necessary, repeated rolling and annealing to obtain a bearing alloy piece of a desired thickness, which includes slitting, annealing, sandblasting, brushing, etc. These bearing alloy pieces are then attached to a backing steel plate by a conventional pressure welding method to obtain a bimetallic piece, which is then annealed and rolled up. These annealed bimetal pieces are then processed into bearing blanks. In these known manufacturing methods, the annealing temperature after rolling and before pressure welding is generally below 230°C, and rarely below 350°C.
℃ or less, and silicon particles were present in a finely dispersed state in the product. (4) Explanation of problems in conventional technology In conventional aluminum alloy bearings, if the content of hard elements such as silicon is high, the fatigue strength of the bearing decreases, and in particular, the bearing slides under repeated loads from the shaft. It was found that there is a drawback that the seizure load is significantly reduced in some cases. Furthermore, it has been found that for the purpose of improving bearing performance, satisfactory results cannot be obtained by methods such as rolling that finely disperse silicon particles. As an example of how such a discovery is completely contrary to the conventional concept of improving bearing performance, the SAE Technical Paper Series' Aluminum
Based Crankshaft Beasings for the High
Paper entitled Speed Diesel Engine (February 1981)
(Announced in Detroit on the 23rd-27th). In it, the seizure load for 11%Si-1%Cu-Al alloy is listed. According to this, silicon particles with a size exceeding 17 microns have a unit area (m ² )
If there are 8.7×10 ⁶ pieces per area, there will be a lot of variation in the seizure load, while if it exceeds 17 microns, it will be 0.6×
10 It is explained that if there are ⁶ pieces, the seizure load will be higher and the variation will be smaller. Furthermore, conventional aluminum-based alloy bearings do not have sufficient seizure resistance or fatigue resistance due to the large amount of solid solution elements in the aluminum matrix, and their fatigue resistance is particularly low under rotational loads. I understand. (5) Purpose of the Invention The present invention provides an aluminum alloy bearing using an aluminum alloy containing tin and silicon, which has excellent seizure resistance and fatigue resistance, and particularly has good fatigue resistance under rotational loads. The purpose is to provide a method for manufacturing. (6) Description of the structure of the invention The present invention is based on a method containing 3 to 15% tin and 1% by weight.
An aluminum-based product comprising a casting process of casting an aluminum alloy material containing ~9% silicon into a plate or strip shape, a rolling process of rolling this alloy material at least once, and a cutting process of cutting the rolled alloy material. In the method for manufacturing an alloy bearing, the process after the casting process includes at least one high-temperature heat treatment process in which the alloy material is heat-treated at a temperature of 450 to 550°C, and the alloy material is treated after the last high-temperature heat treatment process.
It is characterized by having a cooling step of cooling at 300° C./hour or less. The aluminum alloy of the present invention may contain up to 2% of at least one of copper and magnesium, up to 1% of at least one of chromium, manganese, antimony and zirconium, and/or up to 5% of lead. Furthermore, the aluminum alloy
Contains trace amounts of impurity elements such as iron and titanium. Although hot rolling or warm rolling may be used, cold rolling is advantageous from the viewpoint of energy saving. In this case, cold rolling is performed to a degree of workability that is allowable for efficiency, and then annealing is performed. Common. In addition, since hot rolling contains low melting point metals,
Since cracks are likely to occur and are difficult to control, cold rolling is more advantageous from this point of view as well.
In the final step of high-temperature heat treatment, it is most important to perform cooling extremely slowly, that is, to perform cooling at a cooling rate of 300° C./hour or less. In addition, when high-temperature heat treatment is performed two or more times, it is necessary to perform the cooling step of the present application following the high-temperature heat treatment at least in the final step. Of course, if this high-temperature heat treatment is performed once, it may be performed immediately after that step. The present application is a manufacturing method in which the microstructure of an alloy is controlled mainly by the state of silicon precipitation. For this purpose, as described above, it is essential that the cooling method after the high-temperature heat treatment in the last step of the high-temperature heat treatment is 300° C./hour or less. Hereinafter, the configuration of the present invention will be explained in detail. (6-1) Chemical composition First, regarding the chemical composition, tin is an element that changes the properties of the aluminum alloy into softness, 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. When the tin content exceeds 15%, 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 tin content is less than 3%, the compatibility of the general concept as a bearing alloy deteriorates. Add amount of tin from 3 to 15
% 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. The tin content should be low, for example 3 to 8%, and if it is small, the tin content should be high, but if there is a concern about bearing seizure due to high loads and high speed rotation, the tin content should be high. For example 8-15%
You should do it. In order to make the fatigue strength and high-temperature hardness of the tin-containing aluminum alloy sufficient for the performance required as a bearing,
The applicant believes that it is important that tin particles are finely dispersed in the alloy, and in a previous patent application, the coarsening of tin particles that tends to occur when the content exceeds 15% is due to fine particles such as chromium. We made proposals to prevent this from happening. However, in the present invention, since the special running-in effect described later is substantially responsible for 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 tin content is 3-8%. Silicon is an element that brings about a special conforming effect, which will be described later.If its content is less than 1%, the conforming effect will be insufficient, while if it exceeds 9%, fatigue strength and seizure load will tend to decrease, and the shaft will wear out. The preferred silicon content is between 2% and less than 5%. According to the heat treatment of the present invention, which will be described later, the silicon particles become coarser than 5 microns, and the bearing performance of the tin-containing aluminum alloy is dramatically improved.
This effect is noticeable when there are 5 or more silicon particles of 5 microns or more per 3.56 x 10 ^-2 mm ² , and the larger the number, the more pronounced the effect is. On the other hand, when the size of the silicon particles exceeds 40 microns, the fatigue strength of the tin-containing aluminum alloy tends to decrease. In the bearing of the present invention, whether the mating material is a steel shaft or a cast iron shaft, coarse silicon particles have much better performance other than fatigue strength. Therefore, the surroundings of minute irregularities due to the machining accuracy of the shaft, which is the mating material of the bearing containing coarse silicon particles, or the recesses caused by graphite falling from the surface due to the lapping action when the shaft is made of spheroidal graphite cast iron, are It is thought that the silicon particles are flattened and that good sliding occurs with an oil film always interposed between the bearing and the shaft. In addition, in the field of conventional bearings, it is generally believed that soft components such as tin contribute to the conformability of aluminum alloys, and in the SAE journal mentioned above and in other papers published to the best of the inventor's knowledge, There is no concept that hard particles scrape away the surface irregularities of the mating shaft, flatten it, and contribute to conformability. Furthermore, the presence of many hard particles such as coarse silicon particles in a bearing improves bearing performance such as seizure loads. No experimental data has been published that suggests this. Therefore, the above-mentioned special running-in effect is a feature of the present invention, and the bearing performance, for example, the seizure load, is significantly improved when compared with a material having only the conventional running-in effect of the general concept.
Of course, the alloy of the present invention contains tin, but it is believed that 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. is,
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 black cast iron. Spheroidal graphite cast iron tends to be used in place of conventional forged shafts in order to reduce the cost of shafts such as internal combustion engine crankshafts, 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 tin-containing aluminum alloys for bearings have had the problem that these burrs cause abnormal wear on the bearing surface. According to the research of the present inventor, the soft aluminum matrix is scraped off by burrs and incorporated into the recesses.
It has also been found that due to the aluminum and the lack of aluminum conformability of the bearing material, it is very easy to agglomerate, resulting in seizure immediately. However, in the tin-containing aluminum alloy according to the present invention, the coarse silicon particles scrape off 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. Furthermore, the aluminum matrix is modified by heat treatment according to the present invention, which will be described later. The aluminum matrix contains silicon in a supersaturated solid solution during casting. It was discovered that although this silicon peroxide strengthens or hardens the matrix and contributes to improving the strength of the aluminum alloy in a general sense, it is harmful from the perspective of improving the performance of the bearing. Therefore, as a result of studying various heat treatment conditions, the inventors of the present invention have dramatically improved bearing performance by adopting a heat treatment temperature of 450 to 550°C, which is much higher than the annealing temperature used for conventional aluminum bearing alloys. improved significantly. Here, at temperatures lower than 450°C, silicon particles become coarser slightly, but this is not enough to precipitate supersaturated silicon from the aluminum matrix and bring it close to an equilibrium state. On the other hand, at temperatures higher than 550℃, partial melting may occur.
This is not preferable because it induces significant coarsening of tin. Note that the above-mentioned heat treatment temperature is the temperature conventionally employed in solution treatment of Al--Si alloys. For example, according to JP-A-55-12095, an Al-Si alloy having needle-shaped Si crystals is plastically worked to form primary Si crystals into fine spherules, which are then heated to 500°C.
After solution treatment and _T6 treatment, Si
An Al-Si alloy with finely dispersed phases was obtained. Although the Al-Si alloy with such a structure is completely different from that of the present invention, the reason why such different results are obtained is that the tin phase of the present alloy is caused by the coarsening of silicon during heat treatment. This is probably due to the fact that in the present invention, plates or strips are obtained during casting, and the cooling rate is faster than in general casting, die casting, etc., so supersaturation is likely to occur during casting. Therefore,
The heat treatment of the present invention is not a solution treatment because the material and process assumptions are different from those for general Al--Si alloys. Through such heat treatment, supersaturated silicon precipitates, and if there is a certain amount of impurities, the impurities also precipitate inductively, making the aluminum matrix extremely pure and resulting in a matrix with very little solid solution strengthening. becomes. Such matrices are very tough and therefore extremely resistant to fatigue under rotating loads. Therefore, the aluminum alloy bearing according to the present invention can be said to be an ideal bearing that has a balance between seizure resistance due to coarse silicon particles and fatigue resistance under rotational load due to the pure aluminum matrix. (7) Description of Embodiments (7-1) Chemical composition The aluminum alloy bearing of the present invention can contain 2% or less of one or more of copper and magnesium. Almost all of these coppers remain in solid solution in the matrix even after the heat treatment of the present invention, increasing the hardness of the aluminum alloy and contributing to improving the fatigue strength of the bearing. If the content of copper, etc. is less than 0.1%, the hardness improvement effect will be small, and if it exceeds 2.0%, the tin-containing aluminum alloy will become too hard, impairing its rolling properties, and will also reduce its seizure resistance and corrosion resistance to lubricating oil. The hardness-improving effect of copper or the like becomes even more pronounced when it coexists with chromium or manganese, and the hardness does not decrease much even at temperatures of over 200°C. The aluminum alloy bearing of the present invention can contain 1% or less of one or more of chromium, manganese, antimony, and zirconium. Most of these chromium and the like exist as precipitates in the aluminum alloy after the heat treatment according to the present invention, and improve the fatigue resistance against reciprocating loads. Therefore, since the bearing of the present invention containing chromium or the like is inherently excellent in rotational loads, it has extremely excellent performance. moreover,
It can also contain 5% or less of at least one of lead, bismuth, indium, thallium, and cadmium. (7-2) Method for controlling the size and number of silicon particles In general, in Al-Si alloys, most of the silicon crystallizes as needle-shaped eutectic crystals during the casting process, and the cast alloy is rolled to the required thickness for the bearing. During the rolling process, it is divided and its dimensions become smaller. 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. It has a flat or flat shape. Further, in the production of Al alloy bearings, intermediate annealing is performed after rolling, but the temperature is selected to be around the recrystallization temperature, so that the silicon particles hardly become coarse due to the intermediate annealing. On the other hand, coarse silicon particles with a diameter of 5 microns or more and 40 microns or less are 3.56×10 ^-2 mm ²
It has been found that the most effective way to have five or more particles present per bearing alloy is to subject the bearing alloy to a high temperature heat treatment at 350 to 550° C. before the above-mentioned pressure welding. That is,
Silicon particle size control 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. Dimensional control is extremely difficult, 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 tin in the aluminum alloy of the bearing just before completion. , these have undesirable consequences in terms of bearing performance, particularly in terms of 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] Generally, silicon particles in rolled tin-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 of the target in the direction perpendicular to rolling increases and becomes lumpy. When viewed from the horizontal plane of the bearing, that is, the plane in contact with the shaft of the mating material, the silicon particles have a substantially lump-like shape.
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 silicon particles are observed on the above-mentioned horizontal plane to measure the dimensions of the silicon particles.
In addition to silicon particles, intermetallic compounds of chromium, tin particles, and other particles (phases) are present in this alloy, but in order to distinguish silicon particles from these, chromium and tin are separated when viewed with a metallurgical microscope. etc. are white, and silicon particles are gray (dark gray) regardless of the etching method. (7-3) Control of solid solution amount in aluminum matrix 450 to 550℃ within the above temperature range of 350 to 550℃
The heat treatment causes precipitation of supersaturated silicon, etc. The preferred heat treatment time is 3 to 6 hours each time. It is preferable that the cooling rate after heating to 450 to 550°C is slow. Note that in general solution treatment, rapid cooling is usually or essential, but in the present invention, in the cooling step after high-temperature heat treatment,
Because the alloy was cooled slowly at less than 300°C/hour, the microstructure of the alloy became one in which large amounts of silicon precipitated, resulting in extremely excellent fatigue resistance under rotational loads. This is because during high-temperature heat treatment, silicon exists in two states: a precipitated component and a solid solution component that is supersaturated with respect to room temperature, but in the cooling process of the present invention, this supersaturated solid solution silicon is also removed. Most of it precipitates out. Therefore, in the alloy manufactured according to the present invention, the amount of solid solution of silicon in the aluminum matrix after the cooling process is extremely smaller than that in the case of rapid cooling, resulting in a low solid solution matrix for silicon. This low solid solution matrix improves the properties of the alloy, which greatly contributes to improving fatigue resistance under rotational loads. At the same time, the slow cooling rate effectively matures the silicon, which also contributes to improved fatigue resistance under rotational loads. From the above point of view, among the high-temperature heat treatment steps, the cooling step that is performed subsequent to the final step must have a cooling rate of 300°C/hour or less, and in particular, 50°C/hour or less, e.g. 25°C/hour. It is more preferable that In addition, in the manufacturing method of the present invention, the relationship between the copper selectively contained in the aluminum alloy material and the high-temperature heat treatment and cooling of the present invention will be explained in detail again based on the explanation in the column of (7-1) Chemical composition above. I will explain. Copper contained in the present invention is 2% or less. In such a component range, copper exists as a solid solution in the alloy during high-temperature heat treatment, but in the cooling process of the present invention, this solid solution content of copper is substantially retained, and almost all of it is in the matrix. It becomes a solid solution state. In the present invention, the copper that precipitates as a small portion is slowly cooled, so that it precipitates in a relatively large amount. Of course, if the copper content is less than the solid solution amount at room temperature, such precipitation will not substantially occur. As described above, according to the manufacturing method of the present invention, even if copper is contained in an amount larger than the solid solution amount at room temperature, the alloy is not substantially supersaturated and solid solution, but is in a solid solution state close to the equilibrium state. , it can be seen that when the content is less than that, the alloy is in a state in which substantially the entire amount of copper is dissolved in solid solution. Therefore, even if low-temperature heat treatment is performed after the cooling treatment of the present invention, there is virtually no supersaturated solid solution that would precipitate copper, so a stable alloy structure is maintained. . Therefore, the hardness of the alloy is improved by solid solution of copper, and the presence of very small and large precipitates improves the properties of the alloy, contributing to improved fatigue resistance under rotational loads. It happens. For example, when bearings are used under conditions where dynamic loads are relatively low, the degree of slow cooling is increased, and when bearings are used under severe bearing conditions that require high fatigue strength, cooling is more similar to rapid cooling. The degree may be changed. Note that ordinary annealing may be performed in addition to the heat treatment of the present invention. (7-4) Bearing structure The thickness of the bearing alloy mentioned above is 0.1 to 1 mm, especially 0.2 mm.
~0.5 mm 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 a method such as pressure welding. However, if necessary, an overlay and/or
Alternatively, it may have a solid bearing structure. (7-5) Manufacturing process conditions Detailed examples of manufacturing process conditions according to the present invention are shown in the second section.
Shown in the table. These do not limit the invention except for the heat treatment of the invention.

【table】

[Table] (8) Examples 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 of approximately 1 mm. followed by 450-550℃
The aluminum alloy thin plate was heat-treated for 3 hours to obtain silicon particles with a desired size within the range of
The bearing was preheated to 100°C, pressed to a similarly preheated iron backing plate, and annealed at 350°C for pressure welding. Example 1 A bearing was manufactured using an aluminum alloy whose composition is shown in the following table.

[Table] Samples No. 2 and No. 3 in Table 2 are 450-550 above.
This is a comparative example of heat treatment conditions, in which low-temperature heat treatment at 200 to 300 °C was performed instead of high-temperature heat treatment at 200 to 300 °C. In addition to these heat treatment conditions, No. 4 is a comparative example in that the composition does not contain Si. The Si particle size is 400
The five largest images were selected from the double field of view and the average was calculated. Below: Rotation speed: 1000rpm Lubricating oil: 10W-30 Oil temperature: 140℃ Shaft roughness: 0.4-0.6μmRz Shaft diameter: After running under the conditions of 52mm, increase the load temporarily under the same conditions to prevent seizure. When this was reached, the test was stopped and the seizure surface pressure was determined. The results are shown in FIG. In the figure, ● indicates that the DCI shaft is the mating material, and ○ indicates that the steel-filled shaft is the mating material. Next, for Samples 1 to 4, the number of load repetitions at which cracks occurred in the bearing under reciprocating load was determined using the Soda dynamic load tester standard test method under the following conditions. Surface pressure: 0±1000Kg/cm ² Rotation speed: 2100~2400rpm Lubricating oil: 10W-30 Oil temperature: 140±5℃ Shaft type: S55C Hardened shaft roughness: 0.8~1.0μmRz Shaft diameter: 40mm Results are shown in the second As shown in the figure. ● in the figure indicates a crack has occurred.
○ indicates no cracks. Subsequently, for Samples 1, 2, and 4, the number of load repetitions at which cracks occurred in the bearing under rotational load was determined using the standard test method using a triaxial rotating load tester under the following conditions. Surface pressure: 208Kg/cm ² rotation speed: 800rpm Lubricating oil: 10W-30 Oil temperature: 160±5℃ Shaft type: S45C Quenched shaft roughness: 0.4-0.6μmRz Shaft diameter: 48 The results are shown in Figure 3. . Example 2 A bearing was manufactured using an aluminum alloy having the composition shown in Table 4. This bearing was subjected to seizure load measurement under the following conditions. Condition A Tester: Journal type seizure tester Conditions: Compatible shaft - FCD70 or S50C Lubricating oil type - SAE10W-30 Shaft surface roughness - 0.4 to 0.6 μmRz Lubricating oil temperature - 140 ± 2.5°C Shaft rotation speed - 1000 rpm Shaft diameter -52mm Shaft hardness - Hv200-300 (FCD70) (Hv500-600) (S50C hardened material) Load - 50Kg/cm ² /Increased by the same amount at 30mm intervals Bearing roughness - 1 to 1.8μmRz Bearing diameter - 52mm

【table】

[Table] In Table 4, samples 10a and 10b were subjected to high-temperature heat treatment at 460°C for 6 hours and 540°C for 3 hours, respectively. Moreover, 10c is a 6 mm cold rolled plate subjected to high temperature heat treatment. In addition, in the samples of the present invention, the average of the 10 silicon particles from the largest one is 6 to 10 μm (however, No. 9 has a silicon particle size of 6 to 10 μm).
~15 μm). Several samples were tested in the same manner as in Example 1 using the Soda dynamic load tester standard test method and the triaxial rotary load tester standard test method. However, in the former case, the number of repetitions was ¹⁰⁷ times, and the load surface pressure (reciprocating load fatigue surface pressure) at the time the crack occurred was determined. The results are shown in Figure 4. (9) Effects (a) Fatigue resistance under rotational load and fatigue resistance under reciprocating load are well balanced, and both are good. (b) Excellent seizure resistance. Especially when the mating material is DCI
Excellent seizure resistance for shafts. (c) High reliability as there is little variation in seizure resistance and good bearing performance is obtained.

[Brief explanation of drawings]

Figure 1 is a plot diagram showing the seizure surface pressure, Figures 2 and 3 are plot diagrams showing the number of cycles under reciprocating motion and rotational load, respectively, and Figure 4 is a plot diagram showing the fatigue surface pressure under reciprocating load and rotational load repetition. It is a graph showing the number of returns.

Claims (1)

[Claims] 1. A casting process of casting an aluminum alloy material containing 3 to 15% tin and 1 to 9% silicon by weight percentage into a plate or strip shape, and rolling this alloy material at least once. A method for manufacturing an aluminum alloy bearing comprising a rolling process and a cutting process of cutting the rolled alloy material, the process after the casting process including a high temperature heat treatment process of heat treating the alloy material at a temperature of 450 to 550°C. At least once, and following the last high temperature heat treatment step, the alloy material is heated to 300℃/300℃.
A method for manufacturing an aluminum alloy bearing, comprising a cooling step for cooling in less than an hour. 2. The method according to claim 1, comprising a pressure welding step of press-welding the rolled alloy material cut in the cutting step to a back metal, and the high temperature heat treatment step is performed before the pressure welding step. Method. 3. The method according to claim 1 or 2, wherein the aluminum alloy material contains 2% or less of at least one of copper and magnesium. 4. The method according to any one of claims 1 to 3, wherein the aluminum alloy material contains 1% or less of at least one of chromium, manganese, antimony, and zirconium. 5. The aluminum alloy material according to any one of claims 1 to 4, characterized in that the aluminum alloy material contains 5% or less of at least one of lead, bismuth, indium, thallium, and cadmium. Method. 6. The method according to claim 1, wherein the rolling in the rolling step is cold rolling, and the method includes an annealing step of performing annealing after cold rolling. 7. The method according to claim 1, which includes a step of heat treatment two or more times, of which at least one annealing step and at least one high temperature heat treatment step are performed. 8. The method according to claim 1, wherein the casting step is continuous casting, and the aluminum alloy material has a thickness of 5 to 30 mm during casting. 9. The method according to claim 1, wherein the cooling rate in the cooling step is 50° C./hour or less.