Preparation of coated sand by use of phosphate inorganic binder and molding method thereof

Abstract

The invention discloses preparation of coated sand by the use of a phosphate inorganic binder and a molding method thereof. Preparation of the coated sand comprises the following steps: uniformly mixing the phosphate inorganic binder and quartz sand; heating and drying to a semi-dry state; adding calcium stearate with the granularity being 600 meshes and uniformly mixing; and drying and cooling so as to obtain the phosphate inorganic binder coated sand which is in a dry arenaceous state. During molding of the coated sand, the coated sand undergoes hydration only by high temperature steam, the binder is dissolved, sand grains are connected, and finally hot-air is blown for drying and curing molding. The hardening speed is fast. During preparation and curing molding of the coated sand, smell or any harmful gas or substance is not generated. The sand mould has low gas-forming property, is harmless to the health of workers, causes no pollution to the environment and is energy-saving and environmentally friendly. The coated sand provided by the invention has characteristics of high strength, high temperature resistance, low gas evolution, no curing agent required for molding and good storage stability.

Description

Technical field [0001] The invention relates to a preparation method of coated sand, in particular to a preparation method of phosphate inorganic binder coated sand and its forming method. Background technique [0002] Coated sand refers to molding sand or core sand whose surface is covered with a layer of cured resin film before modeling. As an approximate precision casting molding method, coated sand casting has the advantages of simplified process, short molding cycle and low cost compared with lost wax casting methods, making coated sand casting widely used. [0003] In a large number of patents and other documents on coated sand, the binder of coated sand is mostly organic phenolic resin. However, the use of organic phenolic resin as the binder of coated sand has the following problems: [0004] First, the resin has a strong smell, which not only has an odor during the preparation stage of the coated sand, but also when the coated sand is used for modeling, the sand mold is cur...

AI Technical Summary

Problems solved by technology

[0004] One is that the resin has a strong smell, not only in the preparation stage of coated sand, but also when the coated sand is used for molding, the sand mold is heated and solidified, and it is easier to emit an unpleasant smell. Very poor, seriously harming the health of workers;

[0005] The second is that the sand mold generates a large amount of gas during pouring, which can easily cause gas defects in the casting;

[0006] The third is that the high temperature resistance of organic resin coated sand is poor, and the high temperature strength is low;

[0007] Fourth, the recycling performance of coated sand is poor;

[0008] Fifth, the casting of organic resin coated sand is more costly than other sand casting

However, the coated sand prepared by this method has poor collapsibility, and it is difficult to reuse the old sand. In fact, there is no development prospect and cannot be popularized.

[0010] In summary, there is no new type of binder-coated sand that can overcome the defects of existing coated sand products.