Method Of Producing Casting Mold And Casting Mold

Abstract

Purposes of the present invention are to provide a dry coated sand having a high degree of fluidity at the room temperature, a method of advantageously producing the coated sand, and a method of producing a casting mold having excellent properties, by using the coated sand. The dry coated sand is obtained by mixing an aqueous solution of a water glass used as a binder, with a heated refractory aggregate, whereby water in the aqueous solution is evaporated, and a coating layer of the binder is formed on surfaces of the refractory aggregate. A moisture percentage in the thus obtained dry coated sand is controlled so as to be not more than 0.5% by mass. The intended casting mold is obtained by filling a molding cavity of a forming mold, with the dry coated sand, and passing a steam through the coated sand, to solidify or cure the coated sand.

Description

technical field [0001] The present invention relates to a method for producing a casting mold and a casting mold, and more particularly, to a method for producing a casting mold using a dry or wet molding material mixture at normal temperature, and to a casting mold obtained by such a method. Background technique [0002] Conventionally, as one of the methods for producing molds used in molten metal casting, there is known a method of molding into a self-hardening mold using an inorganic binder such as water glass as a binder. However, a mold using an inorganic binder made of water glass suffers from a disadvantage in that the strength of the mold is lowered due to moisture absorption, and thus the moisture resistance is poor, making it difficult to use in an environment with high humidity. In addition, depending on the type of water glass, the moisture resistance strength may be good, but conversely, the moldability tends to be poor, and the conditions of the water glass th...

AI Technical Summary

Problems solved by technology

[0004] However, such a molding material mixture hardly exhibits the effect of moisture resistance in a small amount, so it is necessary to add a large amount of metal oxide more than the solid content of water glass, so even if the moisture resistance strength is improved, the problem of deterioration of moldability cannot be sufficiently solved.

In particular, as for silica, free silicic acid is generated during the kneading process of molding sand and the recycling process of waste sand, and its dust may deteriorate the working environment and cause adverse effects on the human respiratory system, etc.

In addition, a short-term improvement effect of moisture resistance can be obtained, but for example, when the mold is kept in an atmosphere with high humidity for a long time, the problem that the strength of the mold decreases over time due to moisture absorption cannot be sufficiently solved. In particular, when molding a mold at a temperature below 200°C, the strength at the time of moisture absorption is not sufficient even if these conventional moisture resistance-improving additives are used.

Images