JP2011236470A - Aluminum-based bearing alloy and production method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an Al-based bearing alloy that is excellent in non-seizure properties, and a production method thereof.SOLUTION: The Al-based bearing alloy 3 (Al-based bearing alloy layer) contains 1 to 15 mass% of Si, wherein a total length of circumference of Si particles 5 observed in an observation field of 37,820 μmon a slide side surface 3a is 4,000 to 6,000 μm.

Description

  The present invention relates to an Al-based bearing alloy containing Si in the Al group and a method for manufacturing the same.

A plain bearing provided with an Al-based bearing alloy on a base material has relatively good initial conformability, has excellent fatigue resistance at high surface pressure, and is used for a bearing of an internal combustion engine of an automobile. .
A configuration in which the Al-based bearing alloy has better fatigue resistance is disclosed in Patent Document 1, for example. The Al-based bearing alloy of Patent Document 1 contains 1 to 15% by mass of Si and 0.005 to 0.5% by mass of Sr. In addition, this Patent Document 1 discloses that an Al-based bearing alloy withstands a high load and becomes brittle by the action of the refined Si particles by adding Sr to the Al-based bearing alloy and making the Si particles fine. It is also disclosed that the fatigue resistance of the Al-based bearing alloy can be improved.

Japanese Patent Laid-Open No. 3-6345

  In recent years, in addition to the fatigue resistance described above, an Al-based bearing alloy having excellent non-seizure properties has been demanded. That is, in the field of internal combustion engines in recent years, in order to improve fuel efficiency, the connecting rods are thinned to reduce the weight of the internal combustion engine. When the connecting rod is thinned, the rigidity of the connecting rod decreases and the connecting rod itself is easily deformed. For this reason, the plain bearing itself provided on the connecting rod is also easily deformed. As a result, the sliding counterpart member is likely to locally contact the surface on the sliding side of the Al-based bearing alloy of the slide bearing. If this counterpart member continues to slide while in direct contact with the Al-based bearing alloy, seizure may occur.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide an Al-based bearing alloy having excellent non-seizure properties and a method for producing the same.

The present inventor conducted intensive experiments focusing on the size of Si particles in an Al-based bearing alloy in an Al-based bearing alloy containing 1 to 15% by mass of Si. As a result, the present inventor confirmed that the Si particles observed in a predetermined range of the observation field on the surface on the sliding side even if the content of Si particles is the same in the Al-based bearing alloy containing 1 to 15% by mass of Si. It has been clarified that the non-seizure property of the Al-based bearing alloy is good when the total perimeter of is within a predetermined range.
The present inventor has made the following invention based on the above elucidation.

In the Al-based bearing alloy according to the first aspect of the present invention, in the Al-based bearing alloy containing 1 to 15% by mass of Si, the total perimeter of the Si particles observed in the observation visual field 37820 μm ² on the sliding side surface is It is characterized by being 4000-6000 μm.

In the present specification, the Al-based bearing alloy of the present invention will be described by applying it to an Al-based bearing alloy layer provided on a slide bearing base material. The Al-based bearing alloy may be used as a sliding member (slide bearing) without providing the Al-based bearing alloy on the back metal layer.
First, an example of an embodiment of an Al-based bearing alloy is shown in FIG. A plain bearing 1 shown in FIG. 1 includes a base 2 and an Al-based bearing alloy (Al-based bearing alloy layer) 3 provided on the base 2. FIG. 1 shows the surface of the Al-based bearing alloy 3 on the sliding side (sliding counterpart member side) as “surface 3a”.

The base material 2 is a component for providing the Al-based bearing alloy 3, and is a back metal layer formed of, for example, steel or iron.
As shown in FIG. 2, the Al-based bearing alloy 3 includes 1 to 15% by mass of Si (Si particles 5) in a matrix 4 made of Al or an Al alloy. As the proportion of Si in the Al-based bearing alloy 3 increases, the Al-based bearing alloy 3 also becomes harder and the fatigue resistance of the slide bearing 1 is improved. Here, when Si contained in the Al-based bearing alloy 3 is 1 mass% or more, the influence of Si hardness appears, and the effect of improving the fatigue resistance of the slide bearing 1 is obtained. Moreover, when Si contained in the Al base bearing alloy 3 is 15 mass% or less, it can suppress that the Al base bearing alloy 3 becomes weak.
The Al-based bearing alloy 3 contains unavoidable impurities.

In the present embodiment, the total peripheral length of Si (Si particles 5) observed in the observation visual field 37820 μm ² of the surface 3a of the Al-based bearing alloy 3 is set to 4000 to 6000 μm. The surface 3a of the Al-based bearing alloy 3 is observed with an optical microscope. The observation field can be changed by adjusting the observation range of the optical microscope. In this embodiment, the observation field is 37820 μm ² .
The perimeter of each Si particle 5 observed with an optical microscope is measured using image analysis software such as Image-Pro Plus (Version 4.5) (trade name) (manufactured by Planetron Co., Ltd.).

In this embodiment, the total perimeter of the Si particles 5 observed in the observation visual field 37820 μm ² of the surface 3a of the Al-based bearing alloy 3 is set to a predetermined length or more, and in this embodiment, 4000 μm or more. The boundary area with the particle 5 is increased. As a result, the interfacial energy increases at the boundary between the matrix 4 and the Si particles 5, and the increase in the interfacial energy also increases the surface energy of the surface 3a of the Al-based bearing alloy 3, and the wettability of the lubricating oil is high on the surface 3a. Become. Thus, when the wettability of the surface 3a becomes high, the oil film breakage hardly occurs. Therefore, according to this embodiment, the direct contact between the Al-based bearing alloy 3 and the mating member can be suppressed by improving the wettability of the surface 3a. Thereby, the non-seizure property of the AL base bearing alloy 3 is improved.

In the present embodiment, the total perimeter of the Si particles 5 observed in the observation visual field 37820 μm ² of the surface 3 a of the Al-based bearing alloy 3 is set to 6000 μm or less. When the total perimeter of the Si particles 5 is 6000 μm or less, the Si particles 5 are not present in the matrix 4 so that the matrix 4 becomes too hard. Therefore, the conformability of the Al-based bearing alloy 3 of the present embodiment is good.

In the Al-based bearing alloy according to claim 2 of the present invention, the observation visual field 37820 μm ² of the surface on the sliding side is divided into regions for each Si particle by the region division method, and the average value of the aspect ratio of the region is 1-2. It is characterized by that.

As shown in FIG. 2, the region division method refers to a line between adjacent Si particles 5 in the observation field of the surface 3 a of the Al-based bearing alloy 3 (in this embodiment, Si particles 5 in the observation field are voronoied). This is to convert to a polygonal shape, draw a line that becomes a boundary between each other at that time), and divide the observation visual field into the same number of regions as the number of Si particles 5. In the present embodiment, by this region dividing method, the observation visual field 37820 μm ² of the surface 3 a of the Al-based bearing alloy 3 is divided into regions for each Si particle 5 to be observed.

  If the content of Si (Si particles 5) is the same, the size of the Si particles 5 and the number of Si particles 5 have a correlation. That is, if the Si particles 5 are large, the number of Si particles 5 is small, and the area of each region obtained by the region division method is large. On the other hand, if the Si particles 5 are small, the number of Si particles 5 increases and the area of each region decreases.

  The “region aspect ratio” in the present embodiment is the ratio of the major axis length to the minor axis length of the region, that is, the value obtained by dividing the major axis length by the minor axis length. The major axis here means the maximum length in the region obtained by the region division method. Further, the short axis is the length in the direction passing through the center of the long axis and perpendicular to the long axis in this region.

The “average aspect ratio” referred to in the present embodiment is an average value of the aspect ratios obtained by obtaining the aspect ratio for each region obtained by dividing the observation field by the region division method. The observation visual field of this embodiment is 37820 μm ² .
In the present embodiment, the average aspect ratio of this region is 1 to 2. The closer the average aspect ratio of the region is to 1, the more the region is circular or regular polygonal, the Si particles 5 are uniformly dispersed in the matrix 4, and the surface energy of the entire surface 3a of the Al-based bearing alloy 3 is It becomes the same size. Therefore, uniform wettability is obtained over the entire surface 3a of the Al-based bearing alloy 3, and local oil film breakage does not occur. As a result, the non-seizure property of the Al-based bearing alloy 3 is extremely good.

The plain bearing 1 is manufactured through a casting process, a rolling process, a pressure welding process, a heat treatment (annealing) process, and a machining process.
According to a third aspect of the present invention, there is provided a method for producing an Al-based bearing alloy, wherein an Al-based cast plate is formed by cooling Al or an Al alloy containing molten Si by cooling at a rate of 80 to 130 ° C / sec. The Al-base cast plate is rolled at a reduction ratio of 50 to 95% to produce an Al-base bearing alloy.

In the casting process, a molten metal containing Si or Al dissolved therein is cooled at a rate of 80 to 130 ° C./sec to cast an Al-based cast plate. The molten Si is crystallized in the matrix 4 by cooling the molten metal at this speed. The crystallized Si (Si particles 5) is finer than Si (Si particles) crystallized in the conventional configuration.
In the rolling process, the cast Al base cast plate is rolled with a roller or the like. Thereby, the Al base bearing alloy 3 is obtained. The rolling is performed until the rolling reduction (%) in the rolling process is 50 to 95%. The number of rolling is arbitrary, but is preferably 1 to 5 times.
The rolling reduction referred to in the present embodiment is a value indicating how much rolling is performed by rolling compared to before rolling (before rolling process). Specifically, when the rolling reduction is Z (%), the sheet thickness before rolling (before the rolling process) is X (mm), and the sheet thickness after rolling (after the rolling process) is Y (mm), the rolling rate is , “Rolling ratio Z = {(X−Y) ÷ X} × 100 (%)”.

According to the present embodiment, by rolling the Al-based cast plate obtained by the casting process at a reduction rate of 50% or more, the total perimeter of the Si particles 5 observed in the observation field 37820 μm ² of the surface 3a is obtained. An Al-based bearing alloy 3 having a thickness of 4000 μm or more can be obtained.
Further, according to the present embodiment, by rolling the Al-based cast plate obtained by the casting process at a reduction rate of 95% or less, the peripheral length of the Si particles 5 observed in the observation field of view 37820 μm ² of the surface 3a. An Al-based bearing alloy 3 having a total of 6000 μm or less can be obtained.

In the pressure welding process, the Al-based bearing alloy 3 obtained in the rolling process is pressure-welded to the base material (back metal layer) 2. Thereby, the board | plate material for bearing formation is manufactured.
Thereafter, the bearing-forming plate material obtained in the pressure welding process is annealed in a heat treatment (annealing) process and machined in a machining process, whereby the semicylindrical or cylindrical slide bearing 1 is manufactured.

The slide bearing 1 has been described as a two-layer structure of the base material 2 and the Al-based bearing alloy 3. However, an adhesive layer, for example, an intermediate layer such as pure Al is provided between the Al-based bearing alloy 3 and the base material 2. Alternatively, a three-layer structure may be used. Further, an overlay layer made of Bi or Sn, Bi alloy or Sn alloy or the like may be provided on the Al-based bearing alloy 3. When the overlay layer is provided on the Al-based bearing alloy 3, the non-seizure property of the Al-based bearing alloy 3 is exhibited after the overlay layer is worn out.
Further, the Al base bearing alloy 3 may be subjected to a solution treatment to increase the strength of the Al base bearing alloy 3.

Sectional drawing of Al base bearing alloy which shows one Embodiment of this invention Conceptual diagram for explaining the domain decomposition method Side view showing schematic configuration of casting apparatus Side view schematically showing the rolling process

  In order to confirm the effects of the present embodiment, slide bearing samples (Example products 1 to 5 and Comparative products 1 to 3) having an Al-based bearing alloy formed with the components shown in Table 1 were manufactured. A seizure test was performed on the sample.

The manufacturing method of Example goods 1-5 is as follows. First, after dissolving Al and Si in the ratios shown in Table 1, casting is performed by the casting apparatus 11 shown in FIG.
The casting apparatus 11 includes a melting and melting furnace 12 that stores a material for casting. The melting and melting furnace 12 is charged with a melting material having the components shown in Table 1. The components shown in Table 1 contain inevitable impurities.
The casting apparatus 11 includes a bathtub 13 for storing the molten metal poured from the melting and melting furnace 12.

  A molten metal supply nozzle 14 that discharges the molten metal stored in the bathtub 13 is provided in a part of the bathtub 13. A pair of rollers 15 and 15 are provided on the tip side of the molten metal supply nozzle 14 with a minute gap therebetween. The pair of rollers 15 and 15 are disposed such that the axial direction extends in a direction perpendicular to the flow of the molten metal and in the horizontal direction. Thereby, the molten metal in the melting and melting furnace 12 is supplied between the pair of rollers 15 and 15 through the bathtub 13 and the molten metal supply nozzle 14.

  Here, the pair of rollers 15 and 15 are cooled by a cooling pipe 16 which is a cooling means. A plurality of cooling pipes 16 are provided inside the pair of rollers 15 and 15 so as to extend in the axial direction. By supplying a coolant such as water into the cooling pipe 16, the pair of rollers 15 and 15 are cooled. The amount and speed of water supplied to the cooling pipe 16 are adjusted by the degree of opening / closing of a valve (not shown) controlled by a control device (not shown). In the manufacture of the samples of the example products 1 to 5, the molten metal supplied from the molten metal supply nozzle 14 between the pair of rollers 15 and 15 is cooled at a cooling rate of 80 to 130 ° C./sec (the cooling rate shown in Table 1). The degree of opening and closing of the valve is adjusted so as to cool the air. Moreover, cooling at 80-130 degreeC / sec is performed until a molten metal reaches 550 degreeC.

  When the molten metal is cooled and solidified by a pair of rollers 15, 15, a cast Al base cast plate 17 is obtained. The obtained Al-based cast plate 17 is cut at a predetermined length by a cutter 18 and wound by a coiler 19. Next, the Al-based cast plate 17 is rolled by a pair of rollers 20 and 20 shown in FIG. 4 until the rolling reduction reaches the value shown in Table 1 in the rolling process.

  Next, the Al-based cast plate 17 having a predetermined rolling reduction is pressed against the steel plate constituting the base material (back metal layer). Thereby, the board | plate material for bearing formation is manufactured. Then, the bearing forming plate was annealed for several hours, and the bearing forming plate was machined to produce a sliding bearing. The sliding bearings were designated as Examples 1 to 5.

On the other hand, the manufacturing methods of Comparative Examples 1 to 3 differ from the manufacturing methods of Examples 1 to 5 in the following points.
Comparative Example Product 1 was obtained by the same production method as Example Products 1 to 5 except that the rolling reduction in the rolling process was 40%.
The comparative example product 2 was obtained by the same manufacturing method as the example products 1 to 5 except that the cooling rate in the casting process was set to 70 ° C./sec.
Comparative product 3 was obtained by the same production method as that of Examples 1 to 5 except that the cooling rate in the casting process was 70 ° C./sec and the rolling reduction in the rolling process was 40%.

The surface of each sample was observed with respect to Examples 1 to 5 and Comparative Examples 1 to 3 thus obtained, and a seizure test was performed under the test conditions shown in Table 2. These results are shown in Table 1.
Examples 1 to 5 and Comparative Examples 1 to 3 shown in Table 1 are “total sum of peripheral lengths of Si particles” and “average value of area aspect ratio” obtained by photographing a structure with an optical microscope and an observation field of 37820 μm. The image in ² was measured using image analysis software such as Image-Pro Plus (Version 4.5) (trade name) (manufactured by Planetron Co., Ltd.).

Next, the results of the seizure test are analyzed.
From comparison between the example products 1 to 5 and the comparative example products 1 and 3, it can be understood that the example products 1 to 5 are excellent in non-seizure property because the total perimeter of the Si particles is 4000 μm or more. .
From comparison between the example products 1 to 5 and the comparative example product 2, it can be understood that the example products 1 to 5 are excellent in non-seizure property because the total perimeter of the Si particles is 6000 μm or less.
From comparison between the example products 1 to 4 and the example product 5, the example products 1 to 4 are extremely excellent in non-seizure properties because the average value of the aspect ratio of the region obtained by the region division method is 2 or less. I can understand that.
The present invention can be implemented with appropriate modifications within a range not departing from the gist.

  In the drawings, 3 is an Al base bearing alloy, 3a is a surface, 5 is Si particles, and 17 is an Al base cast plate.

Claims (3)

In an Al-based bearing alloy containing 1 to 15% by mass of Si,
An Al-based bearing alloy characterized in that the total perimeter of Si particles observed in an observation visual field of 37820 μm ² on the sliding side surface is 4000 to 6000 μm. ^{2. The} Al region according to claim 1, wherein an observation visual field of 37820 μm ² on the surface on the sliding side is divided into regions for each of the Si particles by a region dividing method, and an average value of aspect ratios of the regions is 1 to 2. Base bearing alloy.   An Al base cast plate is formed by cooling a molten metal containing Al or Al alloy containing Si and cooling at a rate of 80 to 130 ° C./sec, and rolling the Al base cast plate at a reduction rate of 50 to 95%. An Al-based bearing alloy is produced by manufacturing an Al-based bearing alloy.

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