SU1355348A1 - Sand for making moulds and cores - Google Patents

Abstract

The invention relates to foundry and can be used for the manufacture of casting molds and cores used primarily in the production of pressure castings from steel and non-ferrous alloys. The purpose of the invention is to improve the release of the mixture, which is achieved by using glycerin and calcium oxide in the composition. The mixture contains, wt%: orthophosphoric acid 2.0-6.0; glycerin 12.0-20.0; chromium-aluminum phosphate 8.0-12.0 and calcium oxide - the rest. The introduction of the mixture of calcium oxide and glycerin contributes to the strength of the mixture and the improvement of knockability. 1 tab. from sd 01 SLE 4 00

Description

one

The invention relates to foundry and can be used for the manufacture of casting molds and cores used primarily in the production of pressure castings from steel and non-ferrous alloys.

The chain of the invention is an improvement in the yield of the mixture.

The proposed mixture contains orthophosphoric acid, glycerin, phosphate compound and refractory filler,

Phosphoric acid is used as a binder. The density of the acid is 1.651 g / cm. Glycerol is used as a technical grade; chromate phosphate is used as the phosphate compound. Calcium oxide is used as a refractory filler.

Calcium oxide belongs to the group of oxide-phosphate mixtures that harden when heated. The effect of setting this mixture is explained by the

13

heat during solidification of the process- ing mixture is carried out in pressing to remove moisture from the system and crystallize the mixture. Therefore, the mixing of this mixture is carried out in the chill to preserve the vitality of the mixture. The reaction between calcium oxide and orthophosphoric acid can also be slowed by the introduction of phosphate bonds such as chromium aluminum phosphate, which simultaneously reduces cracking during drying and roasting. Glycerin is introduced into the mixture as an inhibitor during the hardening of the composition based on calcium oxide. and phosphoric acid.

The obtained rods and molds, after pouring them with the melt, are well destroyed in water as a result of lime limes flowing with the release of heat and water being added to calcium oxide.

Cao

+ Sa (OH) 2 + 67 kJ,

Calcium hydroxide is well dissolved in water, which causes a good knockability of the mixture of castings.

The preparation of the mixture is carried out as follows.

Orthophosphoric acid and chromium phosphate were preliminarily introduced into glycerol, after which the solution of the phosphate compound was introduced into calcium oxide. The temperature of the components in the mixture is 10

15 2

553482

Pall (-5) - (+ 5) ° С with the subsequent bringing the ready molding sand to (-10) - (- 20) ° С.

The table shows the compositions of the proposed mixtures.

As can be seen from the above data, the forms and rods prepared from mixtures of compounds No. 1-5 have high initial strength, which is necessary when casting steel and non-ferrous alloys under pressure. However, if the molds and the rods from the No. of mixtures are easily destroyed in water, then from the known mixture, which contains in the slag composition May, CaO 43; SiO 47; , 1, the residual strength remains very high (31 MPa), as a result of which the process of dislodging the mixture requires significant energy costs,

If the curing of a known mixture occurs at ordinary temperature, then the production of molds and cores

Forms of nodes pressure is 5-UT / cm, pre-cooled to (-10) - (-20) s. The finished molds and cores are further dried and fired.

The use of the proposed mixture allows to obtain the strength of the mixtures 1.5 times higher than in the prototype and to improve their knockability.

Claims (1)

Invention Formula The mixture for the manufacture of casting molds and cores, used mainly in the production of castings from steel and non-ferrous alloys under pressure, contains a refractory filler, a phosphate compound and orthophosphoric acid, which is different because, in order to improve the blendability of the mixture, it additionally contains glycerin, and as a phosphate compound and a refractory filler, it contains co Responsibly chroman-aluminum phosphate and calcium oxide in the following ratio of ingredients, wt.%: five Orthophosphorus acid Glycerol Chromaluminium. phosphate Calcium Oxide 2.0-6.0 12.0-20.0 8.0-12.0 Else Orthophosphoric acid, GOST 10678-76E Chromium Phosphate Glycerol Calcium Oxide t Monoaluminium Phosphate slag Physical and mechanical properties Compressive strength MPa Residual strength at. compression, MPa (after washing in water) 10 11 12 16 18 20 69 65 61 50 48 45