SU818719A1 - Sand for producing casting moulds - Google Patents

Description

810 kg / m, .1 the purity was characterized by the residue On the sieve 008 in the amount of 16%, the specific gravity was about 3200. The chemical composition of ash in% is presented in Table 1, and its physical characteristics in Table. 2

T a b .I; I c a 1

SiO., ALO ;, F., O; j I CaO; AlgO SO,

pp pp

62.55 29.80 2.94 1.79 0.50 0.21

2.66

table 2

16,0

3200

2.04

The combination of Uios ash with marshalite provides mixtures with gils with a decrease in the value of the thermal expansion coefficient from 0.9 to 0.6%, i.e., by a factor of 1.5 times the average of the composition;

This is due to the fact that, unlike chamotte, (which has a crushing structure, ash yiHoca contains an amorphous component. X-ray phase analysis revealed that the bulk of the ash (95%) is an amorphous glassy phase, formed as a result of its melting.

iB. due to this. ash of ablation in terms of the value of the thermal expansion coefficient (0.4%) is close to the quartite. By the petrographic analysis of M, it was found that in fly ash there are no parts of IB as fragments of non-ethereal, close to oval shape, ranging in size from 0.0001 to 0.1 mm, the number of which reaches 75%. KipOM-e toto, there are spheroidal particles of size from 0.003 to 0.01 mm in an amount up to 20%. For the technological and physical-mechanical mechanics of the molding sand according to the invention, four different combinations were prepared. Getting memeoi with necessary

technological properties (flowability of not less than 16 cm in terms of viocosis; Suttord's meter after 8 minutes from the moment of shutter) was achieved by selecting the optimal water 5 mass ratio. Mixtures should be prepared in the following technological sequence.

In cMKiOCTb with water, it is necessary to withdraw a portion of marshalite calcined at 800 ° C with continuous stirring. The rotation speed of the stirrer is 250-300 rpm. Add a portion of fly ash to the suspension obtained and mix until a homogeneous mass is obtained. After that, with 1np (eryl vnoy mixing), add a weight of 500 grade gypsum. 20-30 s after the introduction of gypsum, the mixture is evacuated at a residual pressure of 10-50 mm Hg. 2-3 minutes The properties of the mixture were applied on samples (mm; mm), poured into metal molds and into metal flasks with dimensions of Ø 160 mm, mm and 0 220 mm, mm with pre-installed model blocks.

From the TOiB, the coated specimens and the forms were kept in air for 1-1.5 hours, after which they were dried in a heating cabinet at a temperature of 110-120 ° C for 2 hours. for 2-3 hours

For comparison, samples and forms were made from a mixture of known composition (jNb 1). The composition of the mixtures: and their physicomechanical and technological properties after calcination at 500 ° C are given in Table. 3 and 4.

T a b l and c a 3 Compositions with. Scales, weight%

Table 4

As seen from. 3, the value of the coefficient of thermal expansion of the mixture is inventive h; it is 144 times less than that of the known, and the strength is higher.

The optimum content of fly ash is in the range of 15-55 wt. % With a further increase in the ash content of the ash 1, the thermal expansion coefficient of the Blend is measured slightly and the strength decreases.

The quality control of garokale forms showed that on molds made from such a mixture, there are cracks and destructions of “collapses of the working surface of the molds by 3-4 times (less than in forms from a known mixture.

This way, the introduction of the ablation zone in the specified amounts allows to obtain molding mixtures with optimal technological and physicomechanical properties. Using an impregnation method, the manufacture of quality molds using the vibrating vacuum method. At the same time, the cost of the formy mixture is reduced by 20-30% due to the low cost of fly ash (7 kopecks for 1 ton).

The quality of otliv0 (to an alloy of Grade AL 9 (GOST 2685-75), poured into these forms) increases as the number of waste, blockages, non-metallic inclusions and other surface defects is 2–3 times less than in the forms of conventional mixture. In connection with this, the labor intensity of the metalwork processing of castings is reduced.

In: a place with the utilization of the ash of Uios, which is the waste of the furnaces of heat and power plants, will contribute significantly (reducing pollution of the environment and the Organization of non-waste fuel combustion technology.

Ф О р м at Л and inventions

The mixture for casting | casting molds, used mainly in the preparation of a single-walled casting of the Sludge configuration, includes marshall, gypsum and aluminosilicate material, which is aimed at improving the quality of the foaming by the reduction of the volumetric changes of the mixture, as an aluminosilicate material mixture contains fly ash from Szhigani solid powdered fuel at the following ratio (ingredients, wt.%:

20-40

Gypsum

15-55

Fly ash

Rest

Marshalit

Sources of information taken into account in the examination:

1. USSR author's certificate number 519272, cl. B 22 C 9/04, 1975.

2. “StaviVO, 1978, No. 1, s. 11-14 (cc).

3. Kesttner O. E. Precise casting of color alloys in plaster and ceramic forms .- M .; Mashgiz, 1968, p. 21.

Claims (1)

The formula of the invention ¹⁰ The mixture for the manufacture of foundry molds, used mainly in the preparation of thin-walled castings of complex configuration, including marshalite, gypsum and aluminosilicate material, I distinguish ¹⁵ that in order to improve the quality of the molds by reducing the volumetric changes in the mixture when heated , as an aluminosilicate material, the mixture contains fly ash from burning solid 20 powder fuel in the following ratio of ingredients, weight. %: R and not Fly ash 25 Marshall 20-40 15–55 Rest