Molding sand for castings

Abstract

The invention relates to molding sand for castings. The molding sand for castings is characterized by being composed of, by weight, 15-25 parts of clay sand, 15-25 parts of quartz sand, 20-25 parts ofglass beads, 20-25 parts of magnesite, 8-15 parts of bentonite, 5-8 parts of zeolite powder, 3-6 parts of titanium dioxide, 2-5 parts of gypsum powder, 5-10 parts of pulverized coal, 25-35 parts of abinder, 10-15 parts of a hardener, 5-10 parts of a coupling agent and 10-13 parts of water. Compared with the prior art, the molding sand for castings is advantageous in that by adopting the clay sand as raw materials, the adhesive property of the molding sand is prominent; and the molding sand for castings is easy to manufacture, low in cost and suitable for secondary utilization after recycling, and using cost is greatly reduced. The glass beads and the magnesite have small expansion coefficients when heated, the glass beads, the magnesite and the quartz sand are mixed to serve as crude sand of the molding sand for castings, the expansion coefficient of the quartz sand is reduced, and thus the condensing rate of castings is uniform, and the surfaces of condensed castings are not prone to cracking and cavity shrinkage. By adding the pulverized coal and the clay, the viscidity of the molding sand for castings can be enhanced.

Description

technical field [0001] The invention relates to the field of ore sand, in particular to molding sand for castings. Background technique [0002] Molding sand for castings is a material used for molding in sand casting. Molding sand for castings plays an extremely important role in foundry production. The casting waste caused by poor quality of casting sand accounts for about 30-50% of the total casting waste. The bonding ability of casting sand is an important index to measure the quality of casting sand. The existing casting sand usually uses water glass as a binder to make water glass sand. Although the bonding effect is relatively good, due to water The price of glass is relatively expensive, so the manufacturing cost of molding sand for castings is also relatively high, and in the actual use of water glass sand, there will be problems such as difficulty in falling sand and difficult regeneration of old sand. [0003] Various casting defects often occur in the production...

AI Technical Summary

Problems solved by technology

[0004] The technical problem to be solved by the present invention is to provide a kind of molding sand for castings, which can solve the problems of cracks and shrinkage holes caused by uneven condensation speed of general casting sand castings, and the problem of poor repeated use effect.