SU484042A1 - Composition for making shell moulds and cores - Google Patents

Abstract

MIXTURE FOR THE MANUFACTURE OF SHEET CASTING FORMS AND RODS contains a refractory filler, novolac phenol-formaldehyde resin, urotropin and calcium stearate, which, in order to increase the strength of forms and rods, it additionally contains an active-active substance. improvement in the wettability of the refractory filler grains with resin, with the following ratio of components, wt.%! Refractory filler - quartz sand • Basis Volphenol-formaldehyde resin 2-6 Urotropin 0.2-0.9 Stearate alci 0.02-0.24 surfactants, for example, a mixture of polyethylene glycol ether ether in mono- and dialkylphenols (OP-7) .0.1-1.2 s!? (LS

Description

The invention relates to the field of foundry, in particular to mixtures for making shell molds and cores.

It is known to apply a hot-clad sand-resin mixture containing a refractory filler, novolac phenol-formaldehyde resin, hexamine and calcium stearate. Curing this mixture in a hot snap allows for shell forms and rods with high strength properties. However, in order to obtain such properties, it is necessary to introduce an increased amount of resin, which leads to a deterioration of sanitary and hygienic working conditions and increased rejects in gas sinks.

The purpose of the invention is to increase the strength of shell molds and cores, which results in a reduction in the amount of resin introduced into the mixture, an improvement in sanitary and hygienic working conditions, and a reduction in rejects in gas sinks.

To achieve this goal, the mixture additionally contains a surfactant in the following ratio of components, May. %;

Refractory filler-quartz

sandbase

Novo.lachna phenol formaldehyde

resin2-6

0.2-0.9

0.02-0.24

0.1-1.2

Preferably, the use of quartz polystyrene of 1K016 or 1K020 grades with a clay content of up to 0.3%, resin is introduced into the mixture in powder form or in flakes, hexamine in the form of a 30% aqueous solution, calcium stearate in the form of powder and surfactant in the form of an emulsion or with an aqueous solution of hexamine.

Hot sand cladding with resin was performed by mixing sand heated to 120-140 ° C with the components introduced in the following sequence: resin, hexamine, surfactant, calcium stearate. The number of components determined efs t content of the resin and the purpose of the mixture.

Due to the introduction of surfactant, the strength of the shells in the cooling state increases by 25-30%, which allows working with a lower resin content. This effect is associated with better distribution of the molten resin over the surface of quartz sand grains.

Example. Of the mixtures, the compositions of which are given in table. 1, make samples (eight) with a thickness of 25 mm for tensile tests. The fabrication is carried out by sandblasting the mixture into the core box. The core box temperature is 240 ° C, the duration of delivery at this temperature is 3 minutes.

The test results are shown in Table. 2

From the test results it can be seen that the introduction of surfactant contributes to an increase in the strength of the mixture by approximately 25-30%. I

t a b l i c i

Basis OciioDa Basis

The foundation

.Table 2

Claims (1)

MIXTURE FOR PRODUCING SHELL CASES AND RODS containing a refractory filler, novolac phenol-formaldehyde resin, urotropin and calcium stearate, characterized in that, in order to increase the strength of the molds and cores, it additionally contains a surface-active substance (surfactant),