JPS5838654A - Casting method for composite member - Google Patents

Abstract

PURPOSE:To cast composite members for cylinder liners, etc. having a good melt stuck state by charging prescribed molten investing metal while the other side to be invested of cast iron or steel products is held heated with preheated molten metal. CONSTITUTION:After Ni or the like is plated on the outside surface of cast iron or steel parts 1, the parts are inserted into a mold 2. First the other molten of a melting temp. equal to or higher than the molten temp. of molten investing metal such as an Al alloy is charged through a sprue 3b for preheating to preheat the parts 1 from the inside. At the point of the time when the temp. of the parts 1 attain an optimum temp., the molten investing metal such as an Al alloy is cast through a regular sprue 3a. The investing metal is joined firmly to the parts 1 by diffusion reaction. The preheating metal is removed after solidification and shrinkage. According to said method, the composite members are cast under optimum conditions with easy work.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for casting a composite member, for example, in casting a cylinder block for an internal combustion engine, in which a cast iron or steel part such as a liner 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. However, the cylinder body surrounding this liner is made of aluminum alloy, which is lightweight and has good heat conductivity, and these are combined with each other.

In such a combination type composite member, in order to ensure good heat conduction between the two and prevent combustion gas from blowing through, it is necessary to prevent air gaps from forming between the two.
For this reason, a method has conventionally been adopted in which cast iron or steel parts such as liners are cast in aluminum alloy or the like. In the overcasting method, in order to improve the wettability between cast iron or steel parts such as liners and the metal, cast iron, and aluminum alloy in which the liner is cast, an alloy is added to the surface of the liner to For example, Id, Cu,
Plating with Nt, N1-P alloy, etc., is generally performed by electroplating or electroless plating.

This also aims to cause a diffusion reaction of cast-in metals such as A/L/MINIRAM and ferrous metals such as liners through the plating layer, thereby improving the fusion properties. The energy required for such diffusion can be obtained by effectively utilizing the heat released during the solidification process of the molten metal, and is therefore limited to the solidification time of the cast-in molten metal. . Therefore, in general, even if the plated liner described above is casted at room temperature, it is difficult to cause a diffusion reaction because the temperature drops the moment the molten metal contacts the liner due to the heat capacity of the molten metal. be.

As a way to solve such problems. Conventionally, methods have been used to raise the casting temperature of the molten aluminum alloy within a range that does not significantly deviate from the casting conditions, or to preheat the liner to a high temperature.
However, because the heat capacity is small, the solidification time is short, the diffusion reaction is not sufficient, and the casting conditions are hindered to some extent. There are methods such as immersion heating in a bath and direct heating with a burner, but in both methods, the process from heating to setting in a mold and casting must be done in a short time, and the work is time-consuming. It has the disadvantage of being complicated.

The present invention solves the above-mentioned conventional drawbacks, and takes a long time until the end of solidification after pouring the molten metal in a cast-wrapping. Therefore, the diffusion reaction with the iron-based metal is sufficient, and the welding property is good. In addition, the cast-in molten metal can be immediately cast in a preheated state, and this casting method does not require complicated work and has excellent workability. Therefore, the present invention provides a method for casting a composite member in which one side of a cast iron or steel part is cast-in with a cast-in molten metal such as an aluminum alloy, wherein the other side of the cast iron or steel part is The cast iron or steel part is preheated by pouring the same or other molten metal as the metal, and in this state, the molten metal is poured.

The structure of the present invention will be explained based on an illustrated embodiment implemented in a cylinder block of an internal combustion engine.As shown in FIG. After applying Ni or other plating metal to its outer surface, it is inserted into a cylinder block mold (2). At that time, the liner (1) is placed inside the liner (1) on the opposite side of the mold chamber (2a) into which the molten metal is placed.
) is provided with a preheating chamber (2b) containing preheated melt and hot water, and in addition to the main sprue (3a) for the cast-in molten metal,
A preheating sprue (3b) is provided for this preheating chamber (2b). First, through this preheating sprue (3b), pour another molten metal that is the same as the cast-in molten metal such as aluminum alloy, or has a higher melting temperature than the molten metal,
゛Preheat the liner (1) from the inside. Liner (1)
When the temperature reaches the optimum temperature, the cast-in molten metal such as aluminum alloy that makes up the cylinder body is poured into the main sprue (3a
). The preheating metal is removed after solidification, and at this time, the cast-in metal forming the cylinder body is strongly joined to the cylinder liner (1) by the diffusion reaction, but the inner preheating metal is aluminum. If an alloy or other metal with a larger shrinkage amount than liner (1) is used, it can be easily extracted. Phosphorus-containing cast iron, the chemical composition of which is shown in Table 1, was used, and a plated metal layer with a thickness of 20μ was applied to the outer surface of the cast iron by electrolytic Ni plating, and the plated metal layer was placed in the mold shown in Figure 1 above. , JIS standard AC4C aluminum alloy as preheated molten metal was placed in the preheating chamber (3) inside the liner (1) at a temperature of 77°C.
After pouring the hot water into b) and preheating it, the same temperature is set at 770°C.
As a result of pouring the 4C aluminum alloy as a cast-in molten metal, the fusion state was extremely good.

Table 1 (a) Next, when we measured the temperature change of the liner (1) during that time, it was as shown in Figure 2, and as shown in this graph.
Compared to those that do not use such preheated molten metal, AC4
It can be seen that it takes a long time for the C molten metal to finish solidifying, so that the diffusion reaction of the aluminum alloy and iron-based metal during this process is sufficiently carried out.

As described above, according to the present invention, cast iron is cast in a state where the cast-in base material of the steel part is heated with preheated molten metal, so the time required for the diffusion reaction to complete solidification is long;
Moreover, it is easy to maintain the cast iron or steel parts at an optimum temperature, and therefore a strong composite member with a good welding state can be obtained. Furthermore, according to the present invention, the cast-in molten metal can be directly poured in the preheated state, which makes the work easier compared to the conventional preheating method, and the temperature of the cast-in molten metal can be kept higher than necessary. It is not necessary to raise the casting temperature to <, which can be carried out under optimal casting conditions.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a mold showing the cast-in method of the present invention, and FIG. 2 is a graph showing the relationship between liner temperature and elapsed time during cast-in in an example of the present invention.

Claims (1)

[Claims] A method for casting a composite member, in which one side of a cast iron or steel part is cast with a metal such as an aluminum alloy, the molten metal of the aluminum-ram alloy or other metal being placed on the other side of the cast iron or steel part. A method for casting a composite member, which is characterized by casting, preheating a cast iron or steel part, and pouring molten metal in this state.