RU2281830C2 - Sand for making casting molds and cores - Google Patents

Abstract

FIELD: foundry, namely manufacture of molds and cores of cold setting sand for making castings of steel, non-ferrous metals and cast iron.

SUBSTANCE: sand contains aluminum boron phosphate concentrate, powder curing agent and quartz sand. Curing agent contains MgO and SiO₂ at next relation of ingredients, mass %: aluminum-boron phosphate concentrate, 3 - 5; powder curing agent, 1.0 - 1.5; quartz sand, the balance.

EFFECT: lowered cost price of cold setting sand production, improved physical and mechanical parameters of sand.

2 tbl

Description

The invention relates to foundry, and in particular to the manufacture of molds and cores from a cold-hardening mixture for casting in the manufacture of castings of iron, steel and non-ferrous metals. The proposed mixture can be successfully used in the foundry industry.

A known mixture comprising a refractory filler, a phosphate binder and triethanolamine, as a hardener. However, the mixture has poor knockability after pouring forms with metal and a small survivability of the mixture. A known mixture for the preparation of molds and cores, containing in its composition alumina-phosphate concentrate - 2.5-5% and refractory filler - the rest (1). However, this mixture is cured by thermal drying, which lengthens the manufacturing process of molds and cores and creates the need to install additional drying equipment.

Closest to the proposed technical essence and the achieved result is a mixture for the manufacture of foundry molds and cores, including a refractory filler, a phosphate binder and calcined magnesite caustic powder in the following ratio of components, wt.%:

Aluminum phosphate concentrate 2.5-4.0 Caustic Calcined Powder Magnesite 0.3-0.5 Quartz sand the rest (2)

The disadvantage of this invention is that this mixture has low survivability, due to the high activity of the hardener, increased flaking and insufficient strength, in addition, the hardener - calcined caustic magnesite powder is currently quite expensive and scarce product.

The objective of the invention is to increase the survivability of the mixture and the ability to control in a wider range of the speed of solidification of the mixture, which is so necessary in foundry, increase strength and reduce the tearing of molds and cores, as well as reduce the cost of the mixture through the use of a cheaper and non-deficient hardener of the mixture.

This object is achieved in that in a mixture for the manufacture of foundry molds and cores containing alumina-phosphate concentrate, powder hardener and quartz sand, the powder hardener contains MgO and SiO ₂ , while the components are taken in the following ratio, wt.%:

Aluminum phosphate concentrate 3-5 Powder hardener 1.0-1.5 Quartz sand rest

For experimental verification of the composition, 6 mixtures of ingredients were made (Table 1), 4 of which showed optimal results (Table 2, items 2-5). Alumina-phosphate concentrate is used as a binder, powder hardener is a hardener, and silica sand is a filler.

The mixture was prepared as follows: the calculated amounts of powder hardener and silica sand were mixed for 1 min, then aluminoborophosphate concentrate was introduced and all this was mixed for another 1 min. Powder hardener contains MgO and SiO ₂ .

The specific surface is 5000 cm ² / g; powder activity - 10 sec.

The compositions and properties of the mixture are shown in tables 1 and 2. The optimal composition of the mixture is determined by the production conditions (requirements for survivability, strength and heat resistance of the mixture).

The introduction of less than 1% of the powder hardener into the mixture leads to an increase in the solidification time of the mixture and a decrease in heat resistance. Introduction to the mixture of more than 1.5% of the powder hardener sharply reduces the survivability of the mixture, strength after 24 hours and heat resistance. The flaking of the mixture increases.

The presence of SiO ₂ in the powder hardener has an additional effect on the survivability of the mixture and the rate of solidification, which is so necessary in foundry, and allows to reduce the cost of the mixture.

Thus, the use of the proposed mixture will allow you to control the solidification time of the mixture in a wide range, increase strength, heat resistance and reduce the tearability of the mixture.

Table 1 Ingredients The content of ingredients, wt.% one 2 3 four 5 6 famous composition Aluminoborphosphate Binder (ABFC) 2.0 2,5 3.0 3,5 4.0 4,5 4.0 Calcined Magnesite Caustic Powder - - - - - - 0.5 Powder hardener 0.9 1,0 1,2 1.4 1,5 1.7 - Quartz sand 97.1 96.5 95.8 95.1 94.5 93.8 95.5 table 2 Mixture properties Composition No. one 2 3 four 5 6 famous composition Vitality, min 60 40 thirty fifteen 6 3 10 Tensile strength kg / cm ³ After 1 hour - 0.8 1,0 1.3 1,5 2.0 0.8 after 24 hours 8.0 9.0 9.5 9.8 10 6.0 3,5 Shedding,% 0.02 0,03 0,035 0.04 0.06 0.2 0.35 Heat resistance at 1000 ° C for 1 hour, kgf / cm ² 0.9 1,0 1,5 1.85 2.05 1.35 1.3

Literature

1. A.S. No. 1639872.

2. A.S. No. 11748914.

Claims (1)

A mixture for the manufacture of foundry molds and cores, containing alumina-phosphate concentrate, powder hardener and quartz sand, characterized in that the powder hardener contains MgO and SiO ₂ , the components are taken in the following ratio, wt.%: Aluminum phosphate concentrate 3-5 Powder hardener 1.0-1.5 Quartz sand Rest