RU2288805C2 - Sand for making casting molds and cores - Google Patents

Abstract

FIELD: foundry, namely compositions of sands for making casting molds and cores.

SUBSTANCE: sand for making casting molds and cores contains next relation of components, mass. %: technical lignosulfonate, 2 - 3; solution of polystyrene in cyclohexane with density 1.2 - 1.4 g/cm³ , 2 - 4; quartz sand, 93 - 96.

EFFECT: improved strength of green and hardened molding sand.

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Description

The invention relates to foundry, in particular to the manufacture of foundry molds and cores.

A technical solution is known, adopted by the applicant for the prototype (Molding materials and mold technology: Handbook / S.S. Zhukovsky, G.A. Anisimovich, N.A. Davydov and others; edited by S.S. Zhukovsky. - M. Engineering, 1993, p.222), which proposes the following composition of the core mixture, wt.%:

Technical lignosulfonate 3 USK-1 3 Refractory filler, e.g. quartz sand Rest

This mixture has high wet fluidity and sufficient dry strength (0.8-1.0 MPa), however, this mixture has significant disadvantages: low wet strength (0.008-0.01 MPa), high cost of the binder USK- one.

The present invention solves the problem of improving the technological properties of the mixture, such as increasing strength in the wet and cured state. And also to abandon the expensive component of the mixture, like USK-1, without compromising the properties of the mixture.

To achieve the technical result, the mixture for the manufacture of foundry molds and cores, including technical lignosulfonate and quartz sand, additionally contains a solution with a density of 1.2-1.4 g / cm ³ polystyrene in cyclohexane in the following ratio, wt.%:

Technical lignosulfonate 2-3 The solution density of 1.2-1.4 g / cm ³ polystyrene in cyclohexane 2-4 Quartz sand 93-96

The increase in strength is achieved due to the presence of polystyrene in the mixture, which, in turn, when the solvent evaporates, has sufficiently high binding abilities.

The essential features characterizing the invention:

Restrictive: The mixture for the manufacture of foundry molds and cores contains technical lignosulfonate and quartz sand.

Distinctive: the mixture additionally contains a solution with a density of 1.2-1.4 g / cm ³ polystyrene in cyclohexane in an amount of 2-4 wt.%.

The mixture is prepared in mixing runners. The components are loaded in the following sequence: a solution with a density of 1.2-1.4 g / cm ^{3 of} polystyrene in cyclohexane is introduced into dry quartz sand, then the mixture is stirred for 1.5-2 minutes, after which lignosulfonate is added and stirred for 2 -3 minutes. The finished mixture is discharged into a dispensing container.

The manufactured rods and molds are cured at a temperature of 170-200 ° C.

The resulting mixture has the properties shown in the table.

Table Indicator Mixture using USK Mix with polystyrene solution Gas permeability 75 85-90 Strength, MPa - wet compression 0.008-0.010 0.011-0.025 - to break after drying 0.8 - 1.0 1.8-2.0 Shedding,% <0.1 <0.1 Knockout good good Surface casting no burn no burn

As can be seen from the table, the inventive mixture has a higher gas permeability and strength in the wet and in the cured state. The increase in the strength of the mixture in the cured state compared with the prototype does not affect the deterioration of knockout.

Claims (1)

A mixture for the manufacture of foundry molds and cores, including technical lignosulfonate and quartz sand, characterized in that it additionally contains a solution of polystyrene in cyclohexane with a density of 1.2-1.4 g / cm ³ in the following ratio of components, wt.%: Technical lignosulfonate 2-3 polystyrene solution in cyclohexane density of 1.2-1.4 g / cm ³ 2-4 Quartz sand 93-96