SU750840A1 - Mixture for manufacturing casting moulds and cores - Google Patents

Description

(5) MIXTURE FOR THE MANUFACTURE OF CASTING FORMS AND RODS

The invention relates to the field of foundry, in particular, to compositions of mixtures on liquid glass binders used to make casting molds and cores. The known mixture for making molds and rods, containing quartz sand, water glass, caustic soda and the addition of an extract for the selective purification of oil distillates Г iTo Introduction of the extract improves the embossability of the mixture of castings. However, due to this, due to the increased content of the extract, this mixture has a high gas content, which can lead to the formation of gas defects in castings. A mixture for the manufacture of casting molds and cores is also known, which, together with the refractory filler and liquid glass, contains an additive of phosphoric flour. The latter somewhat improves the knockout of the molds and cores, however, it does not ensure the required level of their strength and surface quality of cast iron castings D 2. The refractory filler containing the refractory filler is the closest to the described invention in technical essence and the achieved result liquid glass and complex additive in the form of an emulsion, consisting of 0.2-0.3 weight.h. shale flour, 0.2-0.3 weight.h. kerosene or white alcohol and 0.5 weight.h. GTP or sowing 1 on 100 refractory filler J {37 Emulsion of the specified composition requires special training in production conditions. Gross its total consumption of 1.0 weight.h. at 10p weight.h. refractory filler, as provided for in W, moldability and

c (the cores are not sufficiently improved, and an increase in emulsion consumption is hindered by an increase in gas mixing, mixture and deterioration of sanitary and hygienic working conditions in the casting areas due to the intensive formation of smoke during the thermal decomposition of the specified complex additive. .

The purpose of the present invention is to improve the knock-out of the forms and cores and increase their strength.

To achieve this goal, the mixture for the manufacture of casting molds and cores, including a refractory filler, liquid glass and shale powder, contains the specified ingredients in the following ratio, wt%:

Liquid glass 5, Shale powder 1, Refractory fillerOstal

The shale powder in the mixture according to the present invention is characterized by the following property / behavior:

Specific surface area of shale powder fluctuates within 700. Slate is very easy to grind in any aggregates used for grinding lumpy materials — ball mills, jet grinding plants, Katkov runners, and so on.

There are currently no GOST or TU for shale powder, however, there is GOST 7755-77 for combustible Estonian shale.

When the content of shale powder in the mixture below the lower limit does not achieve the desired improvement or knockability, and when its content is above the upper limit, the strength of the molds and cores somewhat decreases.

1000, which corresponds to its dispersion of 0.16-0.05 mm;

shale powder consists of 3555% organic matter and 5-65% mineral substances.

The chemical composition of the organic matter of shale powder is given in Table. one.

Table 1 Composition | S | n | 0 ISJN C1

A distinctive feature of shale powder is its ability to decompose its organic part, starting at a temperature of 170180 ° C. The main decomposition products of organic matter are gases, light and heavy resin vapors, which, moreover, contribute to loosening a film of liquid glass at high temperatures. temperatures and improve the bleedability of the mixtures, they also improve the quality of the surface of the casting.

The chemical composition of mineral substances (ash} of shale powder is given in table 2 "

table 2

The mixture was prepared as follows. Sand and shale powder were loaded into the runners. “They were mixed for 1-2 minutes, after which water glass was introduced and stirring continued for another 4–5 minutes. Standard specimens were made from the resulting mixture, which were subjected to purging with carbon dioxide for 60 s and technological tests.

Instead of hardening with carbon dioxide, it is possible to additionally add in the mixture of hardeners in the form of powders (for example, ferrochrome

57508 “0

slag) or liquids (for example, glycol acetate esters).

The invention is illustrated by the following example.

In tab. 3 shows the compositions of the mixtures No. 1-3 according to the invention and f i according to the known technical solution Z.

Table 3

93.5 92,2591.0 100

5.0 5.25 5.5 5.0 3.5.2, 2

5.8-6.5 6.0-6.5

To illustrate the possibility of using shale powder in self-hardening mixtures, a mixture of the following composition was prepared, wt.%:

Quartz sand

IK02A88,5

Ferrochrome slag 3.5

Liquid glass (module 2.8, density 1.5 g / cm; 5.5

Slate powder 2.5

Continuation of table 3

. ten

Slate Po1, 5 2,5 3,5-1,0 powder

Shale emulsion

including: shale

- - 0.3 flour

0.5

PRS

- - - 0,2

kerosene

% The content for the if 4 mixture is given in parts by weight

Properties of mixtures of tg are given in table. four.

Table k

3.5-, 2 2.0-2.5 6.3-6.7 6.5-7.0

3-6

10-12

The compressive strength of this mixture after 1 h of hardening was 18–20 kgf / cm after 2 h — 3640 kgf / cm, the work of knocking out at 800 C was 1-3 kgm.

Thus, the addition of shale powder to the conditional limits can increase the strength and improve the knock-out of liquid glass.

Claims (1)

mixtures. 7. The formula of the invention. A mixture for the manufacture of casting molds and cores, including a refractory filler, liquid glass and a weak powder, characterized in that, in order to improve the embossability of the molds and cores and increase their strength, they contain the specified ingredients in the following ratio, : Liquid glass 5.0-5.5 Shale powder 1, 5 Refractory fillerEverything else. i) 08 Sources of information taken into account during the examination of 1 USSR author's certificate for application No. 2i 3l65 / 22-02, cl. В 22 С 1/02, 1976. 2о Information leaflet of the Latvian Republican Institute of Scientific-Technical Information and Propaganda of LatINTI), 197, No. 2-7, 10-05 series, p.1, Zo Lipnitskii A.Mo, Sheludov VN Easily liquid mixtures. Publishing house of the Leningrad House of Scientific and Technological Propaganda, Seri. Progressive shaping, metallurgy and heat treatment, Leningrad, Pub., 1969.