SU1565566A1 - Sand for producing permanent casting moulds - Google Patents

Abstract

This invention relates to a foundry, in particular, mixtures for making reusable semi-permanent forms. The purpose of the invention is to improve the quality of the forms by increasing their strength in the wet state and wear resistance. For this purpose, zinc stearate in an amount of 0.5–0.8 wt.% Is introduced into the mixture based on iron powder. A decrease in porosity and an increase in the density of the mold from the mixture, in which zinc stearate is contained, contributes to less oxidation of the metal-form contact layer and to reduce the disturbance of the shape geometry by increasing the strength of the mixture in the wet state by 1.5-2 times, which leads to an increase in quality castings in semi-permanent forms. 2 tab.

Description

FIELD OF THE INVENTION The invention relates to foundry production, namely to compositions. blends for making reusable (semi-permanent) forms.

The purpose of the invention is to improve the quality of the forms by increasing their strength in the wet state and wear resistance.

The essence of the invention is as follows.

The introduction of zinc stearate into the mixture helps to reduce friction between the grains of the mixture, which leads to an improvement in its compactibility, i.e. to increase the strength in the raw state as well as to reduce the porosity. Reducing the porosity and increasing the density of the mold contributes to less oxidation of the metal-form contact layer, the chipping of the form (violation of its geometry) is significantly reduced, which entails an increase in the wear resistance of the form.

The mixture is prepared by mixing its components in a mixer. Then, the molds are made from the mixture obtained by the method of stuffing or pressing in flasks using metal models. After holding for 10-15 minutes, the models are removed from the mold, the molds are kept in air until the end of the exothermic reaction (cooling of the mold) and subjected to sintering atmosphere (endogas) at 1000-1 YuO ° C according to the following mode: heating for 1 h, holding 2 h, cooling Zch.

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The compositions of the proposed mixtures prn13655664

listed in table. one.

Table

Components of the mixture content of components, wt.%,

for mixtures

Zinc stearate 0.50, 60.8 Saturated aqueous solution

sulfuric acid copper 11,013,015,0

Iron powder88,586,484,2

Properties of mixtures 1-3 are given in table. 2

table 2

Properties Indicators for the composition of the mixture

ZEZEUm

Compressive strength, kgf / cm2

raw 0,78 0,97 0,82

after heat treatment 6800 7300. 7,000

Wear resistance, quantity

pouring metal into mold 58 64 41

As can be seen from the data table. 1 and 2, a ny aqueous solution of sulfuric acid copper

the introduction of zinc stearate into the mixture at 30- and iron powder differs to an increase in strength in the raw material so that, in order to improve

the condition of the forms by 1.5-2 times and from the quality of the forms by increasing their

the resistance of the forms is 2.0-2.5 times, the strength in the raw state and from the outside that contributes to the improvement of the quality of resistance, the mixture of additional ratios obtained in semi-permanent 35 will hold zinc stearate with the following

Forms. The ratio of ingredients, wt.%:

Claims (1)

The saturated water formula of the invention is a solution of sulfuric acid medi11.0-15.0 The mixture for the manufacture of foundry 40 Zinc stearate 0.5-0.8 constant forms, including saturated Iron powder The rest Editor I.Gorn Compiled by S.Teplov Tehred L.Oliynyk Proofreader V.Kabatsiy Order 1183 Circulation 626 VNIIPI State Committee for Inventions and Discoveries at the State Committee on Science and Technology of the USSR 113035, Moscow, Zh-35, 4/5 Raushsk nab. Subscription