JPH0366465A - Method for casting parts with fiber reinforcing metal - Google Patents

Abstract

PURPOSE:To prevent seizing of molten metal and to reduce defective rate of casting product by heating a loose core, to which fiber forming body is set. CONSTITUTION:At the time of casting parts with fiber reinforcing metal arranging the loose core 25 between the fiber forming body 27 set in cavity 11 and metallic mold means 23, the loose core 25 is set at the regular position after heating at high temp., and the fiber forming body 27 is set while directly bringing into contact with this, and the molten metal is filled up into the cavity 11. By this method, melt-sticking of the molten metal to the metallic mold, i.e., the development of seizing phenomenon comes to a little and crater on surface of the casting product is drastically reduced and the rate of defective of the casting can be reduced.

Description

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

The present invention relates to a method for casting a fiber-reinforced metal component, and more particularly to a method for casting a molded body containing Ni powder in short ceramic fibers by casting an aluminum alloy to produce NiAl2 as a reinforcing phase.

[Conventional technology]

In a method for casting a fiber-reinforced metal piston in which a molded body containing Ni powder in short ceramic fibers is cast with an aluminum alloy to produce NiAl3 in the reinforcing phase, NiA1. In order to produce this, when the fiber molded body and the molten aluminum alloy are combined, it is preferable to maintain the temperature of the molten aluminum alloy at a high state. A method of increasing the temperature of the mold to hold the high-temperature molten aluminum alloy and reducing the rate of change in temperature drop of the molten aluminum alloy during the process of filling the cavity with the molten aluminum alloy. had been adopted. Such a conventional casting method is disclosed in Japanese Patent Laid-Open No. 61-42463.

[Problem to be solved by the invention]

However, when the mold temperature was increased, the aluminum alloy was fused to the surface of the mold, that is, a seizure phenomenon occurred. When this seizure phenomenon occurs, many craters appear on the surface of the piston when it is removed from the mold. These craters are the cause of defects in the casting (piston). An object of the invention is to increase the temperature only in the vicinity of the fiber molded body in order to prevent the seizure phenomenon of the molten metal and to promote the formation of NiA1. in the fiber reinforced metal, that is, the reinforcing phase.

[Means for Solving the Problems] Therefore, the method for casting fiber-reinforced metal parts of the present invention includes a fiber molded body installed in a cavity, the fiber l1tj,
In a method for casting parts with fiber-reinforced metal in which a millet core is provided between a shape and a mold means, the placing core is heated to a high temperature and then the placing core is placed in a prescribed position of the mold means. death,
The fiber molded body is placed in direct contact with the placed core, and then the cavity is filled with molten metal. [Operation] In this method, when the cavity is filled with molten metal,
The molten metal permeates into the fiber molded body, and the component metals separate and crystallize between the fibers of the fiber molded body at the eutectic point. In this state, the temperature of the molten metal gradually decreases, but since the fiber molding is heated by the heat of the core,
The temperature of the molten metal of the fiber molded body decreases slowly, the molten metal sufficiently penetrates into the fiber molded body, and the crystallization of the component metals is promoted.

【Example】

Hereinafter, one embodiment of the present invention will be described based on the drawings. FIG. 1 shows a vertical pressure casting machine. In the figure, 1 is the lower mold. An upper mold 3 is installed on top of the lower mold l. A pressure plunger 5 for pressurizing the molten aluminum alloy is inserted into these molds L3. This pressurizing plunger 5 is connected to the intermediate plate 7
It is moved up and down by a pressure cylinder 9 supported by. FIG. 2 shows a cavity 11 for casting a piston.
It is shown. The upper mold 3 includes a ball insert (mold means) 15 that forms the inner surface of the piston, and a horizontal core (mold means) 17 and a horizontal core (mold means) that forms the cylindrical surface of the piston.
19 have been installed. Further, a lower mold 1 is provided with a lower mold member (mold means) 23 that forms the combustion surface of the piston. and the horizontal core 17 and the horizontal core 19.Furthermore, on the inner surface of the placed core 25, a fiber molded body 27 is installed between the placed core 25, the horizontal core 17, and the horizontal core 19. Child 1
It is located between 9. This fiber molded body 27 is
It is an annular molded body containing Ni powder inside ceramic short fibers. FIG. 3 shows the placing core 25 in a partial sectional view. A punching slope of about 2 degrees is formed on the outer circumferential surface 251 where the placing core 25 contacts the lower mold 1 in order to facilitate release from the lower mold 23. An annular V-groove 29 is formed in the inner circumferential surface 253 of the piston to prevent the piston casting from separating from the placing core 25 during mold release. Next, the casting process of this example will be explained. With the lower mold 1 and the upper mold 3 separated and opened, the placed core 25 is heated. This placed core 25 is heated to about 00°C to 400 t' in an electric furnace or badge furnace, etc. Using a zero-order setting jig or the like, the heated placed core 25 is placed on the lower part of the servant
to be installed. After that, when the annular fiber molded body 27 containing Ni powder in the ceramic short fibers is placed on the inner circumferential surface 253 of the placing core 25, the upper mold 3 is lowered and the mold is clamped. It turns out. After this mold clamping, the molten aluminum alloy charged in the sleeves (not shown) of the lower mold 1 and the upper mold 3 is
500 to 1000 kJ by pressurizing plunger 5
Filled with a pressure of r/ci. When the cavity is filled with molten aluminum alloy, the molten metal penetrates into the fiber molded body 27 and the component metal (N i A 13) is mixed with ceramic short fibers at the eutectic point, as shown in FIG. It separates and crystallizes between the fibers. In this state, the temperature of the molten aluminum alloy gradually decreases, but the fiber molded body 27 is placed on the core 2.
5, the fiber molded body 27
The temperature of the molten metal decreases slowly, as shown in Figures 5 and 6.
As shown in the figure, the molten aluminum alloy sufficiently penetrates into the fiber compact 27, and the component metal (NiAlg
) will be crystallized throughout the fiber molded body 27. That is, ceramic fiber-reinforced metal (reinforced phase) is formed in the aluminum alloy base material. Then, at the stage when the molten aluminum alloy solidifies, the lower mold 1 and the upper mold 3 are released, and the piston is formed. The casting of the piston with the ceramic fiber reinforced metal (reinforced phase) 41 is then removed as shown in FIG. ,
The final piston 40 will be machined into the shape shown by the dashed-double line in the figure. Note that the first piston ring groove 43 is formed in the ceramic fiber reinforced metal (reinforced phase) 41. Further, the second and third piston rings 45 and 47 are formed in an aluminum alloy base material. Next, the effects of this embodiment will be described. In this embodiment, only the placing core 25 is heated, and the lower mold 1, the upper mold 3, the upper mold 15, the lower mold 23, the horizontal mold 17,
Since the transverse insert 19 is kept at room temperature, the occurrence of seizure of the molten aluminum alloy is reduced, and the defect rate of the cast product is significantly reduced. Furthermore, by heating the placing core 25, N i A 1 ! The crystallization of I is promoted, and a reinforcing phase with excellent heat resistance and wear resistance is formed in the aluminum alloy base material. In addition, only the placing core 25 is heated, and the lower mold 1, the upper mold 3, the upper mold 15, the lower mold 23, the horizontal insert 17, and the horizontal insert 19 are kept at room temperature. The solidification time of molten aluminum alloy is shortened, and the productivity of piston castings is improved. In addition, since there is no need to preheat the lower mold 1, upper mold 3, upper mold 15, lower mold 23, horizontal mold 17, and horizontal mold 19 at the start of operation, the vertical pressure casting machine This will increase the operating time of the machine and improve the productivity of the vertical pressure casting machine. Although specific embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and includes various embodiments within the scope of the claims. be.

【Effect of the invention】

As described above, in the present invention, by only heating the placing core in which the fiber molded body is installed, the fusion of the molten metal to the mold, that is, the occurrence of seizure phenomenon, is reduced, and the surface of the cast product is reduced. craters will be significantly reduced. As a result, the defect rate of cast products is significantly reduced.

[Brief explanation of drawings]

Figure 1 is an external view of the vertical pressure casting machine, Figure 2 is a partial sectional view taken along the -■ break line in Figure 1, Figure 3 is a partial sectional view of the placing core, and Figure 4 is a partial sectional view of the placing core. The figure is a state diagram showing the initial penetration state of molten aluminum alloy into the fiber compact, section 5.
The figure is a state diagram showing the middle stage of penetration of molten aluminum alloy into the fiber molded body, Figure 6 is a state diagram showing the late stage of penetration of molten aluminum alloy into the fiber molded body, and Figure 7 is a state diagram showing the state of penetration of molten aluminum alloy into the fiber molded body. FIG. 2 is a fragmented cross-sectional view showing the product. 11... Cavity 23... Lower insert (mold means) 25... Placed core 27... Fiber molded body

Claims (1)

[Claims] (1) In a casting method for a fiber-reinforced metal component, which includes a fiber molded body placed in a cavity and a core placed between the fiber molded body and a mold means, the core is heated to a high temperature. After that, the placing core is placed in a prescribed position of the mold means, a fiber molded body is placed in direct contact with the placed placing core, and then molten metal is filled into the cavity. A method for casting fiber-reinforced metal parts.