Molding sand for machine molding and preparation method thereof

Abstract

The invention discloses molding sand for machine molding. The molding sand is prepared from the following raw materials in parts by weight: 1-1.5 parts of black talc, 1-2 parts of crystallite biotite, 0.4-0.7 part of sodium gluconate, 15-20 parts of tridymite, 70-75 parts of cristobalite, 1-1.5 parts of molasses, 3-4 parts of sulfite pulp waste liquid, 0.8-1.2 parts of MgO, 0.1-0.3 part of polyaluminium sulfate, 4-5 parts of modified pulverized coal and 4-5 parts of water; the molding sand disclosed by the invention is good in mobility, simple in molding, applicable to machine molding and high in efficiency; during pouring, a part of tridymite is changed into cristobalite, so that cracking difficultly occurs due to high bonding strength, and the phenomena of bonding of a casting and sand are few; and the modified pulverized coal of the molding sand disclosed by the invention contains abundant volatile components and little ash content, is uniform in particles and good in liquidity, thus the brightness of the casting is increased, the defects of pores and sand inclusion are reduced by 10%-13%, and thus the collapsibility is improved.

Description

technical field [0001] The invention relates to the field of casting, in particular to a molding sand for machine modeling and a preparation method thereof. Background technique [0002] The so-called clay green sand for casting refers to the mixture that is mixed with raw sand, binder and attachment in a certain proportion and meets the molding requirements after mixing. Because the materials used in clay green sand casting are cheap and easy to obtain, the casting mold is simple and convenient, and it can adapt to single-piece production and batch mass production of castings. It has been the basic process of casting production for a long time. [0003] Molding sand must have the following characteristics: 1. Good air permeability. After the high-temperature metallic cast iron liquid is poured into the mold, the gas generated must be able to be discharged from the mold smoothly; 2. Good strength, to ensure that the molding sand must have sufficient strength and Concession;...

AI Technical Summary

Problems solved by technology

[0004] Existing castings have many problems, such as sand swelling, sand washing, sand loss, extravasation, pores, pinholes, shrinkage, shrinkage, porosity, cracks, sand inclusions and scarring, sticky sand, rough surface, wrinkles Skin, shrinkage and other phenomena, which have a great relationship with the molding sand, it is necessary to continuously improve the performance of the molding sand, which can be improved from the raw materials and sand mixing process