Expendable salt core for casting

Abstract

An expendable salt core has the shape of a water jacket by, e.g., die casting using a salt of bromine and at least one of sodium and potassium, and a salt of carbonic acid and at least one of sodium and potassium. The expendable salt core is formed to contain at least one of potassium and sodium as a cation, and bromine and carbonic acid as anions. For example, the expendable salt core is formed by casting using a melt obtained by melting a salt mixture of sodium bromide and sodium carbonate.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to a water soluble expendable salt core.[0003]2. Description of the Related Art[0004]As is well known, casting, such as aluminum high pressure die casting (HPDC), is a technique that injects a molten aluminum alloy into a metal mold at a high speed under high pressure to cast a near-net-shape structure. In this casting, when molding a cast product having a hollow structure, e.g., a water cooling water jacket in the closed-deck type cylinder block of an internal combustion engine, an expendable core is used. The expendable core used in such a case must have a strength that can withstand a high pressure and high temperature because it may be subject to a large impact or impulse force fluctuation upon collision of a molten metal injected from the gate at high speed mold filling and because a high static compressive casting pressure is applied until completion of solidification. After casting, ...

AI Technical Summary

Benefits of technology

[0011]According to a preferred embodiment of the present invention, the expendable salt core is formed of a molten salt containing at least one of sodium ions and potassium ions, bromine ions, and carbonate ions. Hence, a water soluble expendable salt core which is formed of a salt cast product obtained by melting and molding salts such as sodium and potassium can be manufactured easily to have a sufficient strength.

Problems solved by technology

When the cast product has a complicated internal structure, it is not easy to remove if a generally used phenol resin bonded sand core is used as the expendable core.

However, when an expendable fused salt core is formed by melting a salt and casting, the formation of a shrinkage cavity, micro-porosity, small heat crack, or the like would be caused in the salt core due to a change in volume such as a solidification shrinkage occurring during the solidification process.

It is therefore not easy to mold the expendable fused salt core precisely conforming to the mold.

In this manner, with the prior art, an expendable fused salt core cannot be easily manufactured by a casting using a molten salt.

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