JPH10237693A - Sliding member made of aluminum alloy and cylinder made of aluminum alloy - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily obtain a sliding member made of an Al alloy having a smooth surface and low in the coefficient of fraction by applying a basis composed of an Al alloy with an anodic oxide layer and working the projecting tip parts of alumina particles projecting at random on the surface into a flat shape by roller burnishing tools. SOLUTION: An anodic oxide layer is formed on the internal face of a cylinder 1 made of an Al alloy by aodic oxidation treatment. The anodic oxide layer on the internal wall 2 is subjected to smooth working by roller burnishing tools 3 formed by providing a supporting body 5 with plural rollers 4. In this way, the tip parts of alumina particles uniformly projecting in the anodic oxide layer are indented, and the surface is smoothly subjected to mirror finishing. At this time, the recessed parts among the alumina particles are allowed to remain to secure the retaining parts of lubricating oil. Furthermore, particles for compounding such as solid lubricants are previously applied and stuck to the surface of the anodic oxide layer, and the working is executed by the roller burnishing tools, by which the smoothing of the anodic oxide layer is attained, and furthermore, the grains for compounding can easily and uniformly be dispersed therein.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a sliding member made of an aluminum alloy.

[0002]

2. Description of the Related Art Conventionally, for example, a sliding surface of an aluminum alloy cylinder of an internal combustion engine is constituted by fine crystallized silicon and a hard alumite layer, and a concave portion serving as a holding portion for lubricating oil is provided.
Improving the abrasion resistance of the sliding surface has been performed (JP-A-61-53444). However, the growth of the alumite layer is uneven depending on the structure and composition of the material. In particular, in the case of an aluminum alloy casting used for a cylinder, the composition tends to be non-uniform due to segregation of alloy components, mixing of a release material, and the like, and the structure tends to be non-uniform due to a difference in cooling rate. As a result, the growth of the alumite layer becomes non-uniform, resulting in a structure in which hard alumina (Al ₂ O ₃ ) 22 randomly protrudes from the surface (FIG. 2). Therefore, the surface pressure is increased at the protruding portion, the friction loss is large, and the piston as the sliding partner is easily worn. Further, since the alumite layer grows along the surface of the material, it is necessary to machine the material in advance with high precision.

[0003]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an aluminum alloy sliding member and an aluminum alloy cylinder in which the above-mentioned disadvantages are solved and the alumite layer is uniformly projected.

[0004]

Means for Solving the Problems In order to achieve the above object, an invention according to claim 1 is directed to a sliding member made of aluminum alloy having a surface provided with an alumite layer on a base material made of aluminum alloy. Is characterized in that the protruding top is processed into a flat shape. According to the invention described in claim 2, in the sliding member made of aluminum alloy, the composite particles are adhered to the surface of the alumite layer and then processed with a roller burnishing tool to form the composite in the alumite layer. It is characterized in that particles are dispersed uniformly. The invention described in claim 3 is characterized in that, in an aluminum alloy cylinder of an internal combustion engine, an alumite layer is formed on the inner surface of the cylinder by anodizing treatment, and the alumite layer is processed smoothly by a roller burnishing tool.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In one embodiment of the present invention, a hard alumite film is formed on the inner surface of an aluminum alloy cylinder by anodic oxidation treatment, and then finished with a roller burnishing tool. That is, the surface of the non-uniformly projected alumite layer is pushed in by a roller burnishing tool to make it smooth. roller·
The burnishing tool is a mirror finishing tool that crushes unevenness on a metal surface with a roller to finish the surface as smooth as a mirror. Unlike the method of finishing by grinding, it is a plastic working method.

FIG. 1 shows an embodiment of the present invention, in which an inner wall 2 of an aluminum alloy cylinder 1 of an internal combustion engine is machined by a roller burnishing tool 3. The roller burnishing tool 3 is configured such that the plurality of rollers 4 are supported by a support 5 and the support 5 is rotated by a driving force from a drive source (not shown). The roller burnishing tool 3 can be used by being mounted on a general machine tool. At the time of the processing operation, the roller 4 is moved to the cylinder 1 as the support 5 rolls.
It rotates while contacting the inner wall of the car. At this time, the metal surface is crushed by the roller 4 and slightly plastically deformed, and the inner wall 2 of the cylinder 1 is precisely finished according to the same principle as that of unevenness of the road with a road roller.

FIG. 2 shows a state after the alumite treatment,
In this state, the holding portion for lubricating oil (21 is formed in the figure, but the surface roughness is large, and the surface pressure during sliding at the protruding tip of the alumite layer 22 increases. , 23 indicate Si particles, 24 indicate an aluminum or aluminum alloy layer, and FIG.3 shows a state after a roller burnishing process, in which the alumite layer 22 has its surface crushed by the roller burnishing tool 3,
Since the shape is pressed into the aluminum alloy material 24, a smooth surface can be obtained. As described above, in order to leave only the concave portion 21 which is a holding portion of the lubricating oil and to smooth only the convex portion 22, a special grinding technique called plate honing is usually required. According to this, a similar surface can be obtained in a time that is 1/10 or less of the grinding.

FIGS. 4 and 5 show another embodiment of the present invention. In this embodiment, the roller burnishing tool 3
By using the fact that the surface of the alumite layer 22 is crushed by the processing of the above, the composite particles 25 such as a solid lubricant are compounded in the alumite layer 22. As shown in FIG. 4, by applying particles 25 on the alumite layer 22 and then performing burnishing on the surface,
The alumite layer 22 becomes smooth as shown in FIG. 5, and has a structure in which particles 25 are composited on the surface. Particle 25
Examples of the method of attaching are methods such as spray coating and electrostatic powder coating. PTF is used as particles of solid lubricant, etc.
E, MoS ₂ , h-BN, graphite fluoride, graphite and the like can be mentioned. Hard ceramic particles such as SiC and Al ₂ O ₃ may be used as composite particles.

The members to which the present invention is applied can be widely applied to aluminum alloy sliding members regardless of the cylinder of the embodiment shown in FIG. The treated surface is preferably composed of a base made of an aluminum alloy in which fine crystallized silicon is dispersed, and a hard alumite layer applied to the base. The hard alumite layer can be generally obtained by using, for example, about 10% by weight of sulfuric acid or about 2% by weight of oxalic acid and performing anodization at a constant current in these electrolytic baths. The processing surface to be subjected to roller burnishing to which the present invention is applied can be formed.

[0010]

EXAMPLE 1 ADC 1 of a 4-cycle, 270 cc generator engine
An alumite layer having a thickness of 15 μm was formed on the inner surfaces of the two cylinders at 5 A / dm ² in 10% sulfuric acid. The alumite layer was finished with a roller burnishing tool. roller·
The surface roughness before and after burnishing improved from 10 to 4 in Rmax. 3,600rpm using this engine
A 10-hour endurance test was performed, and the one provided with an alumite layer and the one subjected to roller burnishing were compared. As a result, in the case of only the alumite layer, traces of biting by foreign matter were found on the skirt portion of the piston and the inner surface of the cylinder. On the other hand, no abnormality was recognized in the roller burnishing.

Example 2 An alumite layer was formed on the inner surface of a cylinder of the same ADC12 material as in Example 1. The surface was sprayed with MoS ₂ and then subjected to roller burnishing. As a result, MoS
_{The two} particles were well dispersed in the alumite layer by roller burnishing, and a smooth surface could be obtained. Using this cylinder, an endurance test was performed at 3,600 rpm for 10 hours. No abnormality was found in the skirt portion of the piston and the inner surface of the cylinder.

[0012]

As is apparent from the above description, according to the present invention, there are provided an aluminum alloy sliding member and an aluminum alloy cylinder in which the conventional inconvenience is solved and the alumite layer is uniformly projected. . That is, according to the present invention, the surface of the alumite layer of the sliding member made of an aluminum alloy is crushed by the roller and becomes smooth, the friction loss is reduced, and the wear of the piston is reduced. Further, since the same effect as that of the plate honing can be obtained in a short time by the roller burnishing tool, the cost is reduced. Further, particles such as a solid lubricant can be easily compounded in the alumite layer by the roller burnishing process, so that the wear resistance can be improved. Further, the fatigue strength of the base material is improved due to the residual compressive stress caused by the roller burnishing. Furthermore, since the finishing process is performed by the roller burnishing process after the anodizing process, there is no need to precisely machine the material before the anodizing process, so that many advantages such as cost reduction can be expected. .

[Brief description of the drawings]

FIG. 1 is a conceptual diagram illustrating a state of manufacturing an aluminum alloy cylinder of an internal combustion engine, which is an aluminum alloy sliding member according to one embodiment of the present invention.

FIG. 2 is a sectional view illustrating a state before a roller burnishing process of the aluminum alloy sliding member according to the embodiment of the present invention.

FIG. 3 is a cross-sectional view illustrating a state in which a sliding member made of an aluminum alloy according to one embodiment of the present invention is subjected to a roller burnishing process.

FIG. 4 is a sectional view illustrating a state before a roller burnishing process of a sliding member made of an aluminum alloy according to another embodiment of the present invention.

FIG. 5 is a cross-sectional view illustrating a state in which a roller burnishing process is performed on an aluminum alloy sliding member according to another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Aluminum alloy cylinder 3 Roller burnishing tool 4 Roller 5 Support body 21 Lubricating oil holding part 22 Alumite layer 23 Si particle 24 Aluminum alloy layer 25 Particles for compounding

Claims (3)

[Claims] 1. A sliding member made of an aluminum alloy having a surface provided with an alumite layer on a base material made of an aluminum alloy, wherein a protruding apex of alumina particles is processed into a flat shape. Element. 2. A sliding member made of an aluminum alloy,
After attaching the composite particles to the surface of the alumite layer,
2. The aluminum alloy sliding member according to claim 1, wherein the composite particles are uniformly dispersed in the alumite layer by processing with a roller burnishing tool. 3. An aluminum alloy cylinder for an internal combustion engine, wherein an alumite layer is formed on the inner surface of the cylinder by anodizing treatment, and the alumite layer is smoothly processed by a roller burnishing tool. cylinder.