SU1419828A1 - Method of producing large moulds with investment patterns - Google Patents

Abstract

The invention is related to foundry. The purpose of the invention is to reduce the manufacturing cycle of forms, reduce their cost, and increase the durability of HoctH and heat resistance. Creature ba way. 3-5 layers of ethyl silicate suspension with sprinkling and drying of each layer are applied to the model block. After the models are melted, all the recesses from the outer part of the mold are filled with a refractory, mixture, and the gating pan is closed with a plug of conductive material. The block prepared in this way is installed in the electrolyzer and the conductive layer is applied by dipping. After removing the block from the bath, sprinkle it with fireclay. Without intermediate drying, the block is immersed in a fortic suspension bath and a layer of 2–5–3 mm thick is applied followed by dusting with chamotte. Next, the block is dried at 40-150 ° C for 2 hours. Depending on the size of the casting, the electrophoretic layer is reapplied

Description

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The invention relates to casting production, and in particular to methods for making molds for melted 1 clothes.

 The purpose of the invention is to reduce the shape of the mold 4a, reduce them (cost, increase strength and heat resistance. I Example. 3-5 layers of ethyl silicate suspension are applied to the model block of model composition P-3 or .MAS,%. I Ethyl silicate 32-11.36 Ethyl alcohol 6.57 Water5.52

Saline acid 0.45 Sulfuric acid 0.32 Dusty quartz 75.3%. Each layer is sprinkled with refractory material - Quartz sand: the first layer is brand KO 16 A (c), the next are C04A (B) and dried at 22-28 ° C within 3.5–4 h. After drying the last iHero layer to a residual moisture of 11.2%, the model is melted out of the mold in a model composition at 135 t 2 ° C or hot air at 170 ±. Consider all the cavities and cavities on the outer side of the mold filled with vibratory refractory material, such as quartz sand or sand, (sand 70%, cement brand 400 15%, water - 15%), and close the holes with clamps from conductive material, such as metal. The bowl of the gating system is tightly closed with a conduit plug.

A block with a cover-electrical lead is installed in the grids of the carriage of the electrolyzer. Next, a conductive layer of the conductive suspension is applied to the block by the dipping method so that the conductive coating touches the clamps — the current lead. After removing the block from the bath and draining the excess suspension, sprinkle it with a granular refractory material - chamotte.

The composition of the conductive suspension, wt.%:

Chamotte pulverized 59.94 Calcium magnesium alumochromophosphate bond modified with virgin chromium40.0

Surfactant (OP-7) 0.06.

Then, without intermediate drying, the block is immersed in a bath with phg) with a reticular suspension, in which the main refractory layer is applied with a thickness of 2.5-3.0 mm by electrophoresis at a voltage of 60 V for 90 seconds.

The composition of foretics suspension, wt.%;

Chamotte dust 40,48 Chamotte granular 27,0 Asbestos2,5

Water30.0

The electrolyte is a 10% aqueous solution of sodium hexometrophosphate 0.2. After removing the block from the bath and draining excess suspension, sprinkle it with granular refractory material - chamotte. Next, the block is dried in a drying chamber at 40 - for 120 minutes to a residual moisture content of 1, 0% according to the mode

1 camera40 t 2 ° С30min

2camera70 t 2 ° С30min

3camera100 ± 2 ° С30min

4camera150 t 2 ° С30min

In the manufacture of large castings, layers are applied to the shell mold by electrophoresis from a conductive and foretic suspension again (2-3 cycles). Before applying each repeated cycle, the mold is cooled to 20-25 ° C by blowing air over it for 15-20 minutes.

The application of subsequent layers by electrophoresis improves the performance and shortens the time of shell formation due to the application of paired layers from a copolymer and foretic suspension, an increase in the thickness of the layers and their simultaneous drying at a higher temperature (from 40 to); contributes to the increase in strength in the heated state and heat resistance of the forms, as well as reducing their cost. This effect is achieved by

that for the preparation of the conductive suspension, a thermally stable and inexpensive binder is used — calcium and magnesium – chromophosphate binder modified with virgin chromium.

The effect of the drying mode on the form properties is given in the table.

When the drying temperature is less than 40 ° C, moisture removal and formation of the durability of the shell made of phosphate binder based suspensions is slow, resulting in poor performance and low strength forms. To achieve a residual moisture content of 1%, the drying time of the molds at 30 ° C is 480 minutes (8 hours). At a drying temperature of 40 ° C and higher, a more intensive removal of moisture and an increase in durability begin.

However, a more intense increase in temperature during the initial period of drying and loss leads to the formation in the form of stresses, cracks and delamination.

Obtaining high-quality shell forms without cracks and delamination with a residual moisture of 1.0% with minimum energy consumption is achieved by drying in the range of 40-150 ° C for 120 minutes.

The optimality of the technological parameters for the manufacture of large-sized shell molds for casting on melted models is explained by the following data.

Putting 3-5 layers of an ethyl silicate slurry on the model provides castings with a clean and smooth surface without being filled with a phosphor from the conductive layer and of sufficient strength to allow models to be melted without breaking the molds when making large castings. Therefore, applying 3-5 layers of ethyl silicate to the model is optimal. Closing the cavities on the outer surface of the mold with pockets of conductive material after they are filled with sand or molding sand in order to create a uniform voltage gradient over the entire surface of the mold and to obtain a uniform coating thickness by electrophoresis is a necessary condition.

About Q

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The plug of the chuggy gating system after the model is removed from the mold by a current lead cap in order to create an electrical contact between the conductive coating and the anode drains is also a necessary condition. Drying in the range of 40-150 ° C is optimal.

The implementation of the proposed method of making molds makes it possible to manufacture large-sized shell forms obtained by electrophoresis, increase labor productivity by reducing the number of applied layers and increase throughput in chamber dryers, and also reduce the cost of forms by replacing an expensive binder (ethyl silicate) with a cheaper one. binder (calcium magnesium alumochromophosphate binder).

Claims (1)

Invention Formula A method of manufacturing large-sized molds based on melted patterns, including layer-by-layer coating of ethyl silicate suspensions on a model, drying each layer, melting the model, closing gating chaga and a plug, and applying a reinforcing coating on the mold, characterized in that, in order to shorten the manufacturing cycle , reducing their cost, increasing strength and heat resistance, after removing the models, the thin-walled cavities and cavities on the outside of the mold are filled with a refractory mixture, and before applying a reinforcing A coating layer was applied to the mold with a refractory powder sprinkled on it, the reinforcement coating was applied by electrophoresis, followed by drying at 40-150 ° C, and the plug was made from a conducting material.