JPS6016301B2 - sliding member - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a sliding member, particularly a light alloy sliding member whose sliding portion (including the sliding surface) is compositely reinforced with inorganic fibers. As a method for compositing the above-mentioned inorganic fibers, the present inventors have developed a technique for forming the above-mentioned fibers into arbitrary shapes and bulk densities, and compositing them at arbitrary locations in the village by high-pressure solidification casting. The above-mentioned inorganic fibers include ceramic fibers (for example, silica fibers, alumina fibers, or crystallized fibers thereof, etc.)
Fibers such as fibers and whiskers (e.g., boron carbide whiskers) are excellent for composite reinforcement. Although these various fibers have low elasticity, they have a relatively high melting point and are hard, and they exhibit excellent abrasion resistance, which is the key to wet dynamic properties, as well as excellent moldability and low cost. It has characteristics. When these fibers are used to compositely strengthen the sliding portion of a light alloy member, various effects can be expected, such as not only strengthening and improving the sliding properties but also improving load resistance. However, one of the physical properties of the above-mentioned fibers is that it deteriorates thermal conductivity, and it cannot be denied that this poses a problem when used in sliding members. In general, in both non-lubricated and lubricated sliding mechanisms, the heat generated in the sliding parts is not cooled by the lubricating medium but is diffused by the mutual thermal conductivity of the members, and the thermal balance of the sliding parts is maintained. Therefore, materials with poor thermal conductivity naturally have poor heat absorption and diffusion properties, which increases the temperature of the sliding parts, resulting in wear, scuffing, etc. A similar phenomenon also occurs when there is a significant difference in thermal conductivity between the sliding member and the slidable member. Therefore, for sliding members,
Not only is excellent wear resistance required, but thermal balance due to thermal conductivity, heat capacity, etc. is also required as an essential element. The present invention has been proposed in view of the above points, and involves various studies on the mechanical strength and thermal balance of the sliding member from the viewpoint of the amount of composite fibers and the thickness of the composite reinforcing layer.
The purpose is to significantly improve the sliding characteristics of this type of sliding part. That is, in a light alloy sliding member made by compositely reinforcing an inorganic fiber molded body of an arbitrary shape in a sliding part by high-pressure solidification casting, the volume ratio of the fiber molded body in the sliding part is set to 30 to 6. %, and the lower limit of the thickness of the composite reinforcement layer is 0.5 fence,
The upper limit of the thickness is 5 legs when the volume ratio is 30 volume%, 2.5 ribs when the volume ratio is 6, and 2.5 sails from the 5 side when the volume ratio is 30 to 60 volume%. It is characterized by a gradual decrease within the range. FIG. 1 shows the relationship between the volume ratio of the fiber molded article of the present invention and the thickness of the fiber composite reinforcing layer, and the trapezoidal part surrounded by A to D is the appropriate range. If the volume ratio of the fiber molded body is less than 30% by volume (region [1]), the composite reinforcement of the light alloy matrix is lacking, the wear resistance is reduced, and matrix scuffing is likely to occur. In addition, the above volume ratio is more than 60% by volume (

In the [0] range), the ceramic properties of the fibers become noticeable and the frictional characteristics tend to deteriorate, and at the same time, wear and severe damage to the sliding member are often accompanied. Also, the thickness of the composite reinforcing layer [
W] range, the thermal conductivity of the sliding surface will be significantly deteriorated, resulting in an increase in the temperature of the sliding surface of the tank. Under lubrication, the thermal load on the oil film will increase, and the fibers themselves will soften and stick, and the sliding surface will increase. Thermal loads on moving parts increase and there is a risk of scuffing or adhesive wear. In addition, if the thickness is thinner than 0.5 skin ([m] area), the rigidity of the sliding surface approximates the rigidity of the matrix, so sufficient load bearing capacity cannot be obtained, and in the case of line or point contact sliding, This is not preferable because the contact area is large and wear increases. The inorganic fibers used in the present invention have a fiber diameter of about 1 to 10 mm, are formed into any shape, and are composited into the sliding part at the time of casting the sliding part. The bulk density of the above-mentioned fiber-formed body is 0.75 to 1.5 m/cc
That's about it. The light alloy matrix material is mainly aluminum alloy (for example, Japanese Industrial Standard code AC group material,
AC4C material, etc.), and if necessary, use a magnesium alloy. The material of the sliding member that is the object of the present invention is mainly cast iron, steel, etc., and it is preferable to subject it to treatments such as chilling, nitriding, sulphonitriding, or induction hardening and carburizing. Examples will be described below. EXAMPLE A case will be described in which the present invention is applied to a rocker arm for an internal combustion engine. FIG. 2 shows the relationship between the rocker arm 1 and the camshaft 2. 3 indicates the slipper surface of the rocker arm 1 that comes into contact with the camshaft, and this portion is the fiber composite reinforcing layer. That is, a fiber molded body having a bulk density of about 1.0 mm/cc is molded to match the shape of the slipper surface so that the fiber volume ratio on the slipper surface is Yokokawamoto volume %, and the molded body is molded using an aluminum alloy. The slipper surface is filled and composited using a high-pressure solidification casting method, and the thickness of the fiber composite reinforced layer after processing is 0.5 2
, 3, 4, and 5 were manufactured. Tests were conducted on the rocker arm, and the temperature of the oil film on the sliding surface and the amount of wear on the slipper and cam surfaces of the rocker arm were examined, and the results shown in Figures 3 and 4 were obtained. In FIG. 4, a shows the amount of wear for the rocker arm, and b shows the amount of wear for the cam. The test conditions were: cam crest radius 17, cam rotation speed 300 pm, spring load 52k9, arm ratio 1:
1. Fu slipper surface radius 26 ribs, slipper surface width 14 willow,
The lubricating oil temperature was 100°C. Further, the amount of wear indicates the value 100 hours after the start of the test. The camshaft is made of chilled cast iron and is nitrided. As is clear from Figures 3 and 4 above, when the thickness of the fiber composite reinforcing layer is about 0.5 ribs, the surface rigidity decreases and the temperature of the sliding surface increases due to the increase in contact area. . It was also found that although no abnormality occurred on the cam surface, the rocker arm slipper surface was prone to wear. It was observed that when the thickness of the composite reinforcing layer was about 2 or 3 ribs, the temperature rise on the sliding surface was small and the amount of wear was small. Furthermore, when the thickness of the composite reinforcing layer was about 4 sides, the temperature of the sliding surface increased because the heat absorption of the slipper surface decreased. It was also found that the thermal load on the cam increased, the cam surface tended to burn, and the amount of wear increased. When the thickness of the composite reinforcing layer is about 5 yen, the temperature of the sliding surface increases and the amount of wear increases significantly. This is due to the occurrence of oil film breakage and adhesive wear caused by fibers. In the above embodiment, the sliding member is made of cast iron and is made of aluminum alloy. Regarding the rocker arm, the fiber volume ratio on the slipper side is about 40 to 5%, and the thickness of the composite reinforcement layer on the slipper side is about 2 to 3. It was found to be the best in terms of oil film retention and balance with the cam side. As described above, by setting the fiber volume ratio of the sliding portion and the thickness of the composite reinforcing layer within the specified ranges of the present invention, it is possible to significantly improve the sliding sardine characteristics.

[Brief explanation of drawings]

Figure 1 is a graph showing the relationship between the fiber volume ratio and the thickness of the fiber composite reinforcing layer, Figure 2 is a front view showing the relationship between the rocker arm and the camshaft, and Figure 3 is a graph showing the relationship between the oil film temperature on the sliding surface and the fiber composite reinforcement layer. A graph showing the relationship between the thickness of the reinforcing layer and FIG. 4 a graph showing the relationship between the amount of wear and the thickness of the fiber composite reinforcing layer. 1 is a rocker arm, 2 is a force shaft, and 3 is a slipper surface. Figure 1 Figure 2 Figure 3 Crocodile diagram

Claims (1)

[Scope of Claims] 1. A light alloy sliding member in which a sliding part is compositely reinforced with an inorganic fiber molded body of an arbitrary shape by high-pressure solidification casting, in which the volume ratio of the fiber molded body in the sliding part is 30. ~60% by volume, and the lower limit of the thickness of the composite reinforcing layer is 0.5 mm,
The upper limit of the thickness is 5 mm at a volume ratio of 30 volume%, 2.5 mm at a volume ratio of 60 volume%, and a volume ratio of 30 to 6
A sliding member characterized in that in the range of 0 volume %, the amount is gradually decreased within the range of 5 mm to 2.5 mm. 2. The sliding member according to claim 1 is a rocker arm for an internal combustion engine, and has a structure in which a fiber composite reinforcing layer under the above conditions is provided on the slipper surface.