JPS58112649A - Casting method for composite member - Google Patents

Abstract

PURPOSE:To cast composite members having perfect melt stickability by setting ferrous metal coated with a low m.p. Al alloy on one side in a casting mold, charging molten metal on the other side thereof, holding the Al alloy in a molten state and charging molten metal for embedding on the one side. CONSTITUTION:A cylinder liner 2 which is beforehand formed with a coating layer 1 of a low m.p. Al alloy on the outside surface thereof is set in a mold 3, and a charging chamber 4 for preheated molten metal is formed on the inner side of said liner 2. A charging chamber 5 for molten metal for embedding is formed on the outer side chamber. Preheated molten metal is charged through a sprue 5a for preheated molten metal and is preheated from the inner side of the liner 2 to hold the Al alloy in a half-molten or molten state; thereafter, the molten metal is charged finally through the sprue 5a for molten metal for embedding.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for casting a composite member, for example, in the casting of an internal combustion engine, in which a ferrous metal such as a liner made of cast iron or steel parts is cast with a dissimilar metal such as an aluminum alloy.

In recent years, in cylinder blocks of internal combustion engines, in order to meet the demands for high heat resistance, wear resistance, and weight reduction, parts that require wear resistance, such as liners, are made of cast iron or steel materials. The cylinder body that surrounds the liner is cast in aluminum alloy, which is lightweight and has good heat conductivity. As described above, conventional methods for casting ferrous metals with aluminum alloys involve placing low melting point aluminum alloys on ferrous metals in a mold in order to improve the fusion properties between the two. The Alfin method and Alumelt method, in which the metal is welded using the heat of molten metal, and the Alfin method, in which the aluminum alloy is immersed and then cast, have been considered. However, in the above-mentioned Alphine method or Alumelt method, even if the Alcovaced material is cast as is, the heat capacity of the cast-in molten metal is insufficient, or an oxide film is formed, making it impossible to obtain sufficient fusion. be. On the other hand, the Alphine method has the disadvantage of poor workability, as there is a work restriction in that the cast-in molten metal must be poured before the deposited aluminum alloy solidifies.

As a method to solve such problems, the inventors of the present invention proposed a method in which molten metal for preheating is poured on the opposite side of the previously deposited aluminum alloy, and main pouring is performed in this state. However, this proposal is based on the surface of ferrous metals.
The aluminum alloy is deposited by electroplating, and in this case, a process of removing gas components generated by the plating solution is required before casting, which has the disadvantage of complicating the work accordingly. The present invention has improved the above-mentioned previous proposal and has improved workability. Cover the aluminum alloy and set it in the mold, and pour the molten metal into the other side.
The method is characterized in that the low melting point aluminum alloy is brought into a semi-molten or molten state, and in this state, molten cast-in metal is poured into the one side.

That is, to explain the structure of the present invention in more detail, first, the cast-in side surface of a ferrous metal made of cast iron or steel parts is coated with a low melting point aluminum alloy. , e.g. 700oC to 800°C
A higher value is preferable in order to thin the coating in which the iron-based metal is immersed for about 3 minutes in a molten metal of a low melting point aluminum alloy.

In this way, the iron-based material coated with a low-melting point aluminum alloy is then placed in a mold and cast-in is performed.
In the present invention, before that, preheated molten metal is poured into the side opposite to the cast-in side, and when the attached low melting point aluminum alloy becomes semi-molten or molten, the molten aluminum alloy cast-in metal is poured into the cast-in side. It is for pouring hot water. The timing to start pouring the cast-in molten metal can be determined in advance by measuring with a temperature needle.

Figure 1 shows a method of casting in a cylinder liner.The cylinder liner (2) has a coating layer (1) of a low melting point aluminum alloy formed on its outer surface in advance.
is set in the mold (3), and a pouring chamber (4) for preheating the molten metal is formed inside the cylinder liner (2), and a pouring chamber (5) for pouring the cast-in molten metal is formed outside the cylinder liner (2). Then, pour the preheated molten metal through the sprue (4a) for preheated molten metal, preheat it from the inside of the cylinder liner (2), and then pour it through the sprue (5a) for cast-in molten metal. It is something.

Next, to explain an example carried out using the above method, first, phosphorous cast iron whose chemical composition is shown in Table 1 was used as a cylinder liner, and it was poured into a molten aluminum alloy with a low melting point at a temperature of 750°C. After being immersed for 3 minutes to coat its outer surface, it was cast by both the method of the present invention shown in FIG. 1 using a preheated molten metal of AC4C phase and the conventional method without such a preheated molten metal.

The temperature of the preheated molten metal at this time was 770°C. The temperature of the cast-in aluminum alloy molten metal was 750°C in both methods.

Table 1 (H) Figure 2 shows the structure of the fused parts of each member thus obtained. In this Figure, the black part in the lower half is the cylinder liner, and the black part in the upper half is The white part shows the cast-in aluminum alloy, and the slightly finer part between the two shows the low melting point aluminum coating layer. A linear oxide film was formed between the aluminum alloy and the cast-in aluminum alloy, and complete fusion was not observed.
It can be seen that the method of the present invention achieves complete fusion without such an oxide film. In the method of the present invention, the temperature of litchi when preheated molten metal is poured into the inside of the cylinder liner is measured at each part of FIG. Due to the above problem, there is a temperature difference between the top and bottom of the liner, which reaches 420°C at the bottom. In this case, it is thought that if the preheating capacity inside the liner is increased and the casting speed is improved, further temperature increases can be expected.

As explained above, according to the present invention, preheated molten metal is cast in advance on the side opposite to the cast-in side of the ferrous metal and preheated to bring the coating metal into a semi-molten or molten state. This method does not cause insufficient adhesion, and even if there is an oxide film on the surface of the coated metal, it is possible to obtain a strong composite member with complete fusion. In addition, in the present invention, even after the aluminum alloy has solidified, it is brought into a semi-molten or molten state by such preheating, so there is no time restriction after coating and workability is good, and it can be attached by electroplating. Unlike the conventional method, there is no need to perform degassing treatment after plating, which simplifies the work process.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view of a mold showing the casting method of the present invention, and FIG.
Figures (A) and (B) are micrographs of the fused parts obtained by the present invention and the conventional method, respectively. Figure 3 shows the temperature changes in each part of the cylinder litchi when preheated molten metal is poured in the present invention. This is a graph showing. (1) ,,,Coating layer, <2) ,,,Cylinder lychee (ferrous metal) 0 Patent applicant Hisashi Tarumoto, Yanmar Diesel Co., Ltd. agent patent attorney
Figure 1a Figure 3/2J 4. f ”J flrl (#Lin) Procedural amendment (method) % formula % 3. Person making the amendment Relationship with the case Patent applicant

Claims (1)

[Claims] One side of a ferrous metal is coated with a low melting point aluminum alloy and set in a mold, and molten metal is poured into the other side to bring the low melting point aluminum alloy into a semi-molten or molten state. A method for casting a composite member, characterized in that a cast-in molten metal is poured into the one side.