Moulding sand for large castings and preparation method thereof

Abstract

The invention discloses molding sand for a large-size cast piece. The molding sand is made of the following raw materials in parts by weight: 250-280 parts of quartz sand, 40-50 parts of sepiolite, 2-4 parts of organic silicon resin, 6-9 parts of furan resin, 1-2 parts of nano-graphite, 5-7 parts of aluminum oxide, 4-6 parts of zinc oxide, 10-15 parts of bentonite, 1-2 parts of pine needle oil, 20-30 parts of bamboo twig and leaf, 1-2 parts of benzenesulfonic acid and a proper amount of water. Due to adoption of sepiolite and bamboo twigs and leaves which are calcined, the molding sand is good in air permeability; with the combination of the organic silicon resin, the furan resin and the like which are ground, the molding sand is excellent in binding property, plasticity, thermal stability and dispersity, low in shrinkage rate and stable in size of the cast piece; due to adoption of the nano-graphite, the dispersity is improved, and the molding is relatively easy; the molding sand disclosed by the invention is relatively high in hardness after being formed, is applicable to large-size cast pieces and is good in binding property; the cast piece is stable in size, the phenomena of loosening and shrinkage holes are reduced, and the finished product rate is high.

Description

technical field [0001] The invention relates to the field of casting, in particular to a molding sand for large castings and a preparation method thereof. Background technique [0002] Molding sand is a material used for molding in casting. Molding sand is generally made by mixing molding materials such as raw sand for casting, molding sand binder and auxiliary additives in a certain proportion. Natural silica sand containing clay can also be used. In the usual molding sand formula for aluminum casting, the particle size of the molding sand is too large or If it is too small, the diameter of the molding sand is too large. Although the air permeability is good, the surface of the aluminum sand parts is rough and the finish is not good. If the diameter of the molding sand is too small, the air permeability of the sand mold is not good, and the aluminum castings have pores. Coal powder clay green sand, which is widely used at home and abroad, is generally made of raw sand, bin...

AI Technical Summary

Problems solved by technology

Molding sand is generally made by mixing molding materials such as raw sand for casting, molding sand binder and auxiliary additives in a certain proportion. Natural silica sand containing clay can also be used. In the usual molding sand formula for aluminum casting, the particle size of the molding sand is too large or If it is too small, the diameter of the sand material is too large. Although the air permeability is good, the surface of the aluminum sand parts is rough and the finish is not good. The diameter of the sand material is too small, resulting in poor air permeability of the sand mold and air holes in the aluminum casting

Coal powder clay green sand, which is widely used at home and abroad, is generally made of raw sand, binders, coal powder additives, etc. and water. It has a certain anti-sticking sand effect, low material cost, and high production efficiency. However, its consumption is large, the emission is serious, and the coal powder is burned and decomposed in the casting process to produce toxic gas pollution.