JPS61172666A - Production of fiber reinforced cylindrical member - Google Patents

Abstract

PURPOSE:To finish the hollow part of a cylindrical member to a smooth surface by using a meltable core in a process for production consisting in combining a fiber molding and a core for forming the above-mentioned core part and disposing the same in a casting mold. CONSTITUTION:The circular cylindrical salt core 11 molded of NaCl under a high pressure is prepared in production of, for example, a hollow piston pin made of an Al alloy compounded and reinforced by inorg. fibers. The inorg. fiber molding 12 made into the shape complying approximately with the shape of the piston pin to be manufactured such as the molding shown in the figure is prepd. parallel with such meltable core 11. The molding 12 and the core 11 are then disposed into a metallic mold 13 and the melt of an Al alloy is poured into the cavity 17 of the mold 13 and is pressurized, by which the molten alloy is packed and compounded into the gap part of the molding 12. The bound body of the Al alloy and the molding 12 is taken out of the mold 13 after solidification. The core 11 in the central part of the molding 12 is dissolved and discharged away in a running water. The piston pin 20 provided with the hollow part 19 is thus obtd.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a method for manufacturing a fiber-reinforced cylindrical member, and in particular, a method for manufacturing a fiber-reinforced cylindrical member, in which a molten metal is filled into the voids of a fiber molded body and composited with a MAN, and the material is formed into a hollow cylindrical shape. The present invention relates to a method of manufacturing a cylindrical member. , K BACKGROUND TECHNOLOGY AND PROBLEMS] As various mechanical devices become lighter and faster, parts designed to eliminate waste material and increase strength are being used. For example, in car engines, hollow piston pins are used to connect the piston and connecting rod, and to increase their strength, they are reinforced with composite inorganic fibers. It looks like this. Conventionally, when manufacturing such a hollow piston pin, it was manufactured as shown in FIGS. 10 and 11. That is, first, an inorganic fiber molded body 1 having a shape corresponding to a hollow piston pin is prepared, and this molded body 1 is
was placed in a mold, and the voids of the hollow inorganic fiber molded body were filled with pickled metal such as aluminum alloy to form a compound. After the aluminum alloy is solidified, the aluminum alloy 2 filled in the hollow part of the inorganic 1!11 formed body 1 is removed by cutting or other removal processing, so that the center A piston pin 4 having a hollow portion 3 was manufactured. Since such a piston pin 4 has a hollow portion 3 in its center, it is lightweight, and has high strength due to the composite reinforced inorganic fiber molded body 1.
This will contribute to improving engine performance. However, according to the conventional manufacturing method of such a hollow piston pin 4, removal processing such as cutting is required to form the hollow portion 3, and furthermore, cutting powder of light alloy such as aluminum alloy is generated. There is. Furthermore, if pressure casting is used to completely fill the voids of the hollow inorganic fiber molded body 1 with the molten aluminum alloy 2, the inorganic fiber molded body 1 will be deformed by the pressure of the molten metal. This results in the disadvantage that the inorganic fibers 1 are not properly composited at the predetermined positions of the piston pins 4. In particular, since the inorganic 111i molded body 1 is hollow, the molded body 1 is easily distorted on the inner peripheral side. For the purpose of omitting this, attempts have been made to use a mold core 5 as shown in Fig. 12.This core 5 is made of steel, and this core 5 is As shown in Fig. 12, the hollow inorganic fiber molded body 1 is assembled and placed in a mold, and in this state, the molten aluminum alloy is injected.
The voids in the 1lli compact 1 are filled with aluminum alloy. By using the core 5 of such a mold, if the core 5 is removed after the aluminum alloy 2 is solidified, the first
A hollow piston pin 4 as shown in FIG. 3 is obtained. However, when the aluminum alloy 2 solidifies, a fusion layer is formed between the aluminum alloy and the steel core 5, and the aluminum alloy is firmly attached to the outer peripheral surface of the core 5. . Therefore, the core 5 of this mold
When removed, galling occurs on the inner circumferential surface of the hollow portion 3. Furthermore, since the outer periphery of the mold is tapered to make it easier to remove the core 5 from the mold, there is a drawback that it becomes difficult to make a piston pin 4 that is too long. ``Object of the Invention'' The present invention has been made in view of the above problems, and provides a method for omitting the process of forming the hollow part of a cylindrical member by removal processing, and also finishing the surface of the hollow part smooth. It is an object of the present invention to provide a method for manufacturing a fiber-reinforced cylindrical member.

Summary of the Invention 1 The present invention is directed to the manufacture of a cylindrical member in which the voids of a fiber molded body are filled with molten metal to be composited with fibers, and the cylindrical member is formed into a hollow cylindrical shape. In the method, a soluble core having a shape corresponding to the hollow portion is prepared, and this soluble core is combined with an Ill1 molded body formed into a shape corresponding to the cylindrical member or its composite reinforcement portion, and placed in a mold. , relates to a method for manufacturing a fiber-reinforced cylindrical member, characterized in that molten metal is filled into the voids of the fiber molded body to form a composite material, and after solidification, the soluble core is melted to form a hollow part. This method eliminates the need for a removable process to form the hollow part, and also ensures that the surface of the hollow part has a predetermined level of smoothness, and that the composite reinforced inorganic fiber molded product is not deformed. It is something. KEmbodiment 1 The present invention will be described below with reference to an illustrated embodiment. In this embodiment, the present invention is applied to a method of manufacturing a hollow piston pin made of aluminum alloy composite reinforced with inorganic fibers. When forming such a hollow piston pin, a cylindrical salt core 11 as shown in FIGS. 1 and 2 is first prepared. This salt core 11 constitutes a soluble core, and sodium chloride particles are molded under high pressure of about 2000 kg/d. The higher the pressure for molding the soluble core 11, the more it can withstand the subsequent pressure casting. Therefore, when injecting aluminum alloy molten at high pressure, it is desirable to mold the soluble core 11 at higher pressure. If the salt core 11 is press-molded into a cylindrical shape, the salt core 11 will be
Sinter for about 2 hours at ℃. The soluble core 11 thus obtained is very strong and has sufficient strength to withstand high-pressure casting of molten metal. In parallel with the soluble core 11, an inorganic fiber molded body 12 as shown in FIGS. 3 and 4 is prepared. In this embodiment, the inorganic fiber molded body 12 is made of alumina ceramic fiber containing 95% by weight or more of alumina. The proportion of the inorganic fibers after being combined with the aluminum alloy is approximately 10% by volume. This inorganic mm molded body 12 is made to have a shape that substantially corresponds to the shape of the piston pin to be manufactured. Such an inorganic fiber molded body 12 and the above-mentioned soluble core 11
is placed in a mold 13 shown in FIG. This mold is for manufacturing a piston pin by pressure casting, and is composed of a cylindrical mold 14 and a lower mold 15. In this mold 13, the inorganic fiber molded body 12 and the cylindrical salt core 11 are placed in combination. Furthermore, a fixed amount of molten aluminum alloy of JIS AC8A, for example, is injected into the cavity 17 of the mold 13. Then, a pressure of about 1000 kg/c (approximately 1,000 kg/cm) is applied to the molten aluminum alloy 16 from above using the punch die 18. Due to this pressure, the molten aluminum alloy 116 is applied to the voids of the fiber-free molded body 12 placed in the cavity 17. It will be filled with melted aluminum alloy!
i16 and the inorganic 111 ft molded body 12 are completely integrated into a composite. FIG. 6 shows the mold 13 after solidifying the thus pressure-cast combination of the aluminum alloy and the inorganic fiber molded body 12.
This figure shows the state taken out from the inorganic fiber molded article 12, and the soluble core 11 is fitted into the center of the inorganic fiber molded article 12. Then, this soluble core 11 is dissolved in running water and drained out. Then, as shown in FIG. 7, a piston pin 20 having a hollow portion 19 consisting of a through hole in its center is obtained. Hollow piston pin 2 obtained by the method of this example
0, the hollow portion 19 is formed by dissolving the soluble core 11 in running water as described above.
Eliminates the need for removal processes such as boring to form. Therefore, cutting powder of light alloys such as aluminum alloys is not generated. The surface roughness of the hollow portion 19 obtained by roughly removing the soluble core 11 is very fine, and a value of 25 to 30 seconds has been measured as a result of trial production. Therefore, even if a special surface roughening specification is required, the machining process for that purpose is so simple that only one step is required. Furthermore, when filling the voids of the inorganic fiber molded body 12 with molten aluminum alloy by pressure casting, since the inner circumference of the inorganic fiber molded body 12 is supported by the soluble core 11, the pressure It is possible to reliably prevent the molded body 12 from being undesirably deformed by the molten aluminum alloy during the casting process. Therefore, it is possible to provide a piston pin 20 that can properly compositely strengthen the inorganic fiber molded body 12 at a predetermined position. Next, a piston pin 20 manufactured by a method according to a modification of the above embodiment will be explained with reference to FIG. This piston pin 20 has a hollow portion 19 whose diametrical dimension is different between the outlet side and the inner part, and the dimension is smaller in the inner part. That is, the piston pin 20 has a thicker wall thickness at the center portion, and is provided with a thicker wall portion 21 . Such a thick part 21
The shape of the above-mentioned soluble core 11 is made into such a hollow part 1.
9, it can be easily formed. Alternatively, as shown in FIG.
may be partially formed in the intermediate portion. Note that this thick portion 21 is provided in a portion where high shear stress is generated. Also in this case, by making the shape of the salt core 11 correspond to the shape of the hollow portion 19 of the piston pin 20, it becomes possible to easily form the salt core 11. Therefore, the degree of freedom in design also increases. Although the present invention has been described above with reference to the illustrated embodiment and its modified examples, the present invention is not limited to the above-described embodiment, and various modifications can be made based on the technical idea of the present invention. For example, the above embodiment relates to a method for manufacturing a piston pin, but the present invention can also be applied to a method for manufacturing cylindrical members such as cylinders and bushes, which have high wear resistance and high strength. It is. Furthermore, in the above embodiments, alumina-based l fibers are used as the inorganic fibers, but silica-based inorganic fibers, or ceramic fibers that are a mixture of alumina-based inorganic IIN and silica-based inorganic fibers, silicon carbide and silicon nitride whiskers,
It is also applicable to cylindrical members compositely reinforced with metal fibers such as stainless steel. Furthermore, although the above embodiment relates to a method for manufacturing a piston pin made of an aluminum alloy, it can be applied to casting of metals that melt at a temperature lower than the melting point of the soluble core, such as magnesium alloy, zinc alloy, lead alloy. Alternatively, it can also be used in a method for manufacturing a 1a fiber-reinforced cylindrical member cast from a titanium alloy or the like. [Effects of the Invention] As described above, the present invention provides a method for preparing a soluble core having a shape corresponding to a hollow portion, and molding this soluble core into a shape corresponding to a cylindrical member or its composite reinforced portion. It is arranged in a mold in combination with a fiber forming body, molten metal is filled into the voids of the mm molded body to form a composite, and after solidification, the soluble core is melted to form a hollow part. Therefore, according to the present invention, since the hollow portion can be formed by melting the soluble core, it is possible to omit the step of forming the hollow portion by removal processing. Furthermore, the surface roughness of the hollow portion formed by melting the soluble core can be made smooth, and galling will not occur on the inner surface of the hollow portion. Furthermore, since the soluble core prevents the inorganic fiber molded body from being deformed by molten metal, it becomes possible to correctly compound and reinforce the inorganic fibers at predetermined positions.

[Brief explanation of drawings]

FIG. 1 is an external perspective view of a soluble core used in a manufacturing method according to an embodiment of the present invention, FIG. 2 is a front view of the same, FIG. 3 is an external perspective view of an inorganic fiber molded product, and FIG. Fig. 5 is a longitudinal sectional view of a mold for manufacturing a piston pin, Fig. 6 is a longitudinal sectional view of a mold for manufacturing a piston pin
The figure is a vertical cross-sectional view of an aluminum alloy produced by fF using this mold, and Figure 7 is a vertical cross-sectional view of the resulting piston pin.
FIG. 8 is a longitudinal cross-sectional view of a piston pin according to a modified example, FIG. 9 is a vertical cross-sectional view of a piston pin according to another modified example, and FIG. 10 is a cast body of an aluminum alloy for manufacturing a conventional piston pin. FIG. 11 is a vertical cross-sectional view of the piston pin obtained by this method, FIG. 12 is a vertical cross-sectional view showing a method of manufacturing a piston pin using a mold core, and FIG. 13 is a vertical cross-sectional view of the piston pin obtained by this method. It is a longitudinal cross-sectional view of the obtained piston pin. In the symbols used in the drawings, 11... Cylindrical salt core (soluble core) 12... Inorganic mm molded body 13... Mold 16... Molten aluminum alloy 17... Cavity 19 ...Hollow portion 20...is a piston pin.

Claims (1)

[Claims] In a method for manufacturing a cylindrical member in which the void portion of a fiber molded body is filled with molten metal and composited with the fibers, the cylindrical member is formed into a cylindrical shape with a hollow interior, the shape corresponding to the hollow portion. A soluble core is prepared, and this soluble core is placed in a mold in combination with a fiber molded body formed into a shape corresponding to the cylindrical member or its composite reinforcement part, and the molten metal is poured into the fiber molded body. 1. A method for manufacturing a fiber-reinforced cylindrical member, characterized in that the hollow portion is formed by filling a cavity and forming a composite material, and then melting the soluble core after solidification to form a hollow portion.