Pre-coated sand

Abstract

The invention relates to pre-coated sand which comprises crude sand, an adhesive, a curing agent and a coupling agent. The amount of the curing agent accounts for 40-60 percent of the total amount of the adhesive, the amount of the coupling agent accounts for 0.2-0.5 percent of the total amount of the adhesive, the amount of the adhesive accounts for 1-1.5 percent of the total amount of the crude sand, the crude sand has the granularity of 100-150 meshes and is prepared from the components in parts by weight: 70-80 parts of yellow sand, 10-20 parts of diatomite and 5-15 parts of high-temperature cement, and the adhesive is prepared from the following components in parts by weight: 5-10 parts of thermosetting phenolic resin and 90-95 parts of thermoplastic phenolic resin. The invention not only has favorable heat resistance, smaller roughness and better permeability but also can prevent sand from adhering to a casting.

Description

a coated sand technical field The invention relates to casting sand, in particular to coated sand, which is particularly suitable for making casting sand molds. Background technique Coated sand refers to the molding sand or core sand that is covered with a solid resin film on the surface of the sand grains before molding. There are two coating processes: cold method and hot method: the cold method dissolves the resin with ethanol, and adds urotropine during the sand mixing process, so that the two are coated on the surface of the sand grains, and the ethanol volatilizes to obtain coated sand; Preheat the sand to a certain temperature, add resin to melt, stir to coat the resin on the surface of the sand, add urotropine aqueous solution and lubricant, cool, crush, and sieve to obtain coated sand. For steel castings and iron castings. Due to the advantages of high strength, low gas generation, high dimensional accuracy of production castings, smooth surface and easy storage...

AI Technical Summary

Problems solved by technology

The purpose of the present invention is to overcome the defects and problems of poor heat resistance, large roughness, and easy sand sticking on castings existing in the prior art, and to provide a casting with good heat resistance, small roughness, and not easy to stick on castings. Coated sand for sticky sand on castings