JPS6338717A - Light alloy sliding member - Google Patents

Abstract

PURPOSE:To improve the scratch critical characteristics and the seizure critical characteristics of a sliding member by permitting the profile irregularity in the sliding part of a cylinder block, which is made up of a fiber reinforced light alloy, to be not more than one half of the average diameter of reinforcing fibers. CONSTITUTION:A cylinder block 1 for internal combustion engines is made of light alloy, such as aluminum or the like, and the internal wall part 1a of a cylinder bore 2 is comprised of a fiber reinforced light alloy. As the reinforcing fiber, alumina fibers are used, and the profile irregularity in the internal wall part 1a is set to be not more than one half of the average diameter of the alumina fibers. Hereby, falling of the alumina fibers can be prevented, and at the same time, the quantity of abrasion in the opposite member can also be reduced, and therefore, the scratch critical characteristics and the seizure critical characteristics of a sliding member can be improved accordingly.

Description

DETAILED DESCRIPTION OF THE INVENTION A6 Object of the Invention (1) Industrial Field of Application The present invention relates to an improvement in a light alloy sliding member, particularly in a sliding member made of a fiber-reinforced light alloy.

(2) Prior Art Conventionally, no special consideration has been given to the relationship between the surface roughness of the sliding portion of the light alloy sliding member and the average diameter of the reinforcing fibers.

(3) Problems to be solved by the invention However, scratches and seizure phenomena in sliding parts are promoted by reinforcing fibers that have fallen off from the light alloy matrix. The fibers must be firmly held in the light alloy matrix, and for this purpose it is necessary to specify the surface roughness of the sliding part with respect to the average diameter of the reinforcing fibers.

As described above, the present invention specifies the relationship between the surface roughness of the sliding part and the average diameter of the reinforcing fibers to firmly hold the reinforcing fibers in the light alloy matrix, thereby achieving scratch limit characteristics and seizure limit characteristics. It is an object of the present invention to provide the above-mentioned light alloy sliding member which has the following characteristics.

B0 Structure of the Invention + 1) Means for Solving the Problems The present invention provides a light alloy sliding member in which the sliding portion is made of a fiber-reinforced light alloy, in which the surface roughness of the sliding portion is determined by the reinforcing fiber. It is characterized by being set to one-half or less of the average diameter of.

(2) Effect With the above structure, on the sliding surface of the sliding part, the reinforcing fibers dispersed with their axes arranged substantially parallel to the sliding surface have approximately half of them in the light alloy matrix. The reinforcing fibers are embedded in the matrix and retained in the matrix, thereby suppressing the reinforcing fibers from falling off. On the other hand, the reinforcing fibers arranged and dispersed with their axes substantially perpendicular to the sliding surface are embedded in a large amount in the light alloy 7 trisox, so their relationship with the surface roughness is small.

(3) Embodiment Figures 1 to 3 show a cylinder block 1 for an internal combustion engine as a sliding member made of a light alloy, and the inner wall portion 1a of the cylinder bore 2, which is the sliding part, is made of a fiber-reinforced light alloy. be done. An aluminum alloy is used as the light alloy, and alumina fiber, which is a ceramic fiber, is used as the reinforcing fiber.

The cylinder block 1 is made by placing a cylindrical molded body made of alumina fiber in the cavity of a mold preheated to 200'C, and heating an aluminum alloy specified by JIS 8DC12 at a temperature of 730 to 740C and a filling pressure. 260
It is cast by casting at kg/J. A fiber-reinforced aluminum alloy is obtained by filling and compounding the aluminum alloy into the molded body during casting of the cylinder block.

An aluminum alloy piston 3 is slid into the cylinder bore 2, and two compression rings 4 and one oil shovel ring 5 are attached to the piston 3.

Figure 4 shows the results of a chip-on-disk sliding test between a fiber-reinforced aluminum alloy with a volume content of alumina fibers of various diameters set at 10.0% and a mating material, spheroidal graphite cast iron (JISFCD75). show. The line (1) corresponds to the seizure limit characteristic, and the line ([[) corresponds to the scratch limit characteristic.

The alloy corresponds to the constituent material of the inner wall portion 1a of the cylinder bore 1, and the tip is formed of this material.

Further, the cast iron corresponds to the constituent material of the compression ring 4, and the disk is formed from this material. The sliding surfaces of these chips and disks are polished so that they have various surface roughnesses of 1.0 μm or more. In this case, the reason why the surface roughness is set to 1.0 μm or more is that it takes a lot of effort to obtain a surface roughness lower than that by polishing.

The test method was to rotate the disk at a speed of 9.5 m/s, press the sliding surface of the chip against the sliding surface of the disk with a predetermined pressing force without lubrication, and check the surface roughness and burnout of each chip. The relationship between the surface pressure acting on the chip at the sticking limit and the scratching limit is determined.

As is clear from Figure 4, the surface roughness of the chip is 1.0~
If it is in the range of 3.0 μm, the surface pressure at the scratch limit is about 25 to about 35 kg/-, and the surface pressure at the seizure limit is 66
The sliding properties are as high as ~82 kg/cd, which is sufficient for practical use.

In such a sliding test between a fiber-reinforced aluminum alloy chip and a cast iron disk, scratching and seizure phenomena are promoted by alumina fibers falling off from the matrix of the chip during the sliding test. Therefore, it is necessary to firmly hold the alumina fibers in the matrix, and in order to satisfy this requirement, the surface roughness of the chip is preferably set to 1/2 or less of the average diameter of the alumina fibers. With this setting, approximately half of the alumina fibers distributed on the sliding surface of the chip with their axes arranged approximately parallel to the sliding surface are embedded in the matrix and held in the matrix. This suppresses the alumina fibers from falling off. On the other hand, the alumina fibers, which are arranged and dispersed with their axes substantially perpendicular to the sliding surface, are embedded in a large amount in the matrix, so their relationship with the surface roughness is small.

Considering the above points, the average diameter of the alumina fibers is 2.
When it is set to 0 to 6.0 ttm, the surface roughness of the chip is set to 1.0 to 3.0 μm. For best sliding properties, the average diameter of the alumina fibers should be between 2.0 and 4.
It is set to 0 μm, and the surface roughness of the sliding surface is set accordingly.

FIG. 5 shows the results of a chimp-on-disc sliding test between fiber-reinforced aluminum alloys with various volume contents of alumina fibers having an average diameter of 3 μm and a mating material, spheroidal graphite cast iron (JIS FCD75). The line (Illa) corresponds to the seizure limit characteristic, and the line (llrb) corresponds to the scratch limit characteristic.

The alloy corresponds to the constituent material of the inner wall portion 1a of the cylinder pore 2, and the chip is formed from this material.

Further, the cast iron corresponds to the constituent material of the compression ring 4,
This material forms a disk. The surface roughness of the chip and disk is set to 1 μm.

The test method was to rotate a disk at a speed of 9.5 m/s, and place the sliding surface of the chip on the sliding surface of the disk.
The chips were pressed with a predetermined pressing force under the KA slide, and the relationship between the volume content of alumina fiber in each chip and the surface pressure acting on the chip at the seizure limit and scratch limit was determined.

As is clear from Fig. 5, when the volume content of alumina fiber is set to 8.0 to 20.0%, the surface pressure at the scratch limit on the chip is about 30 to about 95%, as shown by the line (■b).
kg/c4, and the surface pressure at the limit of seizure is as high as about 70 to about 170 kg/cut, as shown in line (Illa). Furthermore, the fibers reinforcing the tip and therefore the sliding part are sufficiently reinforced, and the wear resistance is also excellent, and furthermore, the amount of Ir wear on the mating material can be reduced.

However, when the volume content is less than 8.0%, the fiber reinforcing ability is small and the wear resistance and seizure resistance are reduced.

On the other hand, if the volume content exceeds 20.0%, the filling properties of the aluminum alloy matrix will deteriorate, making it impossible to achieve sufficient fiber reinforcement, and the hardness of the sliding parts will increase, causing wear and tear on the mating material. The amount increases, and the heat transfer coefficient also decreases.

In FIG. 5, lines (IVa) and (rVb) respectively correspond to the seizure limit characteristics and scratch limit characteristics of a hybrid fiber-reinforced aluminum alloy chip in which alumina fibers and carbon fibers are mixed. In this case, the volume content of carbon fiber (relative to the total volume of the chip) is set to 0.3%.

In this way, in a hybrid type chip, its seizure limit characteristic and scratch limit characteristic are line ([a)
, (IIIb) is clearly improved.

However, if the volume content of carbon fiber is less than 0.3%,
If the above-mentioned effect based on the lubricating ability of carbon fiber cannot be obtained, and on the other hand, the above-mentioned volume content exceeds 20.0%, the total volume content will decrease in relation to the amount of alumina fiber, and the mixed fiber will not be used. When obtaining a molded article, moldability deteriorates. Therefore, the appropriate volume content of carbon fiber is 0.3 to 20.0%. Note that since carbon fiber has a lubricating ability, even if it falls off from the matrix, the scratch limit characteristics etc. will not be impaired.

FIG. 6 shows the results of a chip-on-disc wear test of fiber-reinforced aluminum alloys with various volume contents of alumina fibers having an average diameter of 3 μm and a mating material, spheroidal graphite cast iron (JIs FCD75). The line (V) corresponds to the wear amount of the alloy, and the line (Vr) corresponds to the wear amount of the cast iron.

The alloy corresponds to the constituent material of the inner wall portion 1a of the cylinder bore 1, and the tip is formed of this material.

Further, the cast iron corresponds to the constituent material of the compression ring 4,
This material forms a disk. The surface roughness of the chip and disk is set to 1 μm.The test method is to rotate the disk at a speed of 2.5 m/s, and apply a pressing force to the sliding surface of the chip with the sliding surface of the disk under lubrication. 20kg
This state was maintained until the sliding distance reached 2000 m. The amount of lubricating oil supplied is 2 to 3
ml/min.

As is clear from Fig. 6, when the volume content of alumina fiber is set to 8.0 to 20.0%, the line (V)
The amount of wear on the tip is small, about 0.5 to about 0.85 μm, as shown by the line (Vl), and the amount of wear on the disk is about 2.0 μm, as shown by the line (Vl).
The thickness is reduced to 85 to about 5 μm.

In order to minimize the amount of wear on the chips and disks, it is preferable to set their surface roughness to 1 μm or less and the volume content of alumina fibers to 12.0 to 14.0%.

The alumina fibers include long fibers, short fibers, whiskers, etc., and include, for example, Safil (trade name) manufactured by ICr Corporation and Fiber FP (trade name) manufactured by DuPont. As other reinforcing fibers, conventionally known fibers such as alumina-silica fibers can also be used.

Since the diameters of individual reinforcing fibers are different, the average diameter of the reinforcing fibers refers to the average value thereof. In this case, reinforcing fibers include those with circular cross sections as well as those with non-circular cross sections such as elliptical and polygonal cross sections, so the diameter of non-circular reinforcing fibers is determined from the cross sectional area.

Note that the present invention is not limited to cylinder blocks for internal combustion engines;
It also applies to other members. Moreover, a magnesium alloy or the like can also be used as the light alloy.

C0 Effects of the Invention According to the present invention, by specifying the surface roughness of the sliding part with respect to the average diameter of the reinforcing fibers as described above, the reinforcing fibers are firmly held in the light alloy matrix, and the scratch limit is reduced. A light alloy sliding member with improved characteristics and seizure limit characteristics can be provided.

[Brief explanation of drawings]

Figure 1 is a perspective view of the cylinder block, Figure 2 is a plan view of the cylinder block, Figure 3 is a sectional view taken along the line m-■ in Figure 2, and Figure 4 shows the sliding characteristics in relation to the surface roughness of the chip and disk. Figure 5 is a graph showing the relationship between the surface pressure acting on the chip, Figure 5 is a graph showing the sliding properties as a relationship between the volume content of alumina fiber and the surface pressure acting on the chip, and Figure 6 is a graph showing the relationship between the volume content of alumina fiber and the surface pressure acting on the chip. It is a graph showing the relationship between volume content and wear amount of chips and disks. l... Cylinder block as an aluminum alloy sliding member, 1a... Inner wall of cylinder pore as a sliding part Patent Author: Honda Motor Co., Ltd. Agent
Patent Attorney Ochiai Combined use 1 Figure 4 E IUL of the surface of the knob and L screen (I-1m) Figure 6 Volume content of the lumi-su fly force ('/,) Figure 5

Claims (5)

[Claims] (1) A light alloy sliding member in which the sliding part is made of a fiber-reinforced light alloy, characterized in that the surface roughness of the sliding part is set to one-half or less of the average diameter of the reinforcing fibers. Light alloy sliding member. (2) The light alloy sliding member according to claim (1), wherein the surface roughness of the sliding portion is set to 3.0 μm or less. (3) The light alloy sliding member according to claim 1 or 2, wherein the reinforcing fibers have an average diameter of 2.0 to 4.0 μm. (4) The light alloy sliding member according to claim 1, 2, or 3, wherein the reinforcing fibers are ceramic fibers. (5) The light alloy sliding member is a cylinder block for an internal combustion engine, and the sliding part is an inner wall part of a cylinder bore. The light alloy sliding member according to item (4).