SU1565576A1 - Method of producing castings - Google Patents

Abstract

The invention relates to metallurgy, in particular, to special methods for producing castings in electron beam installations (ELU), and can be used in the manufacture of cast copper crystallizers used for ECL and ESR, and other water-cooled chill molds with a complex shaping surface. The purpose of the invention is to increase the density of castings and reduce the complexity of their manufacture. The method includes the melting and refining of copper in a sealed ELU chamber and its subsequent pouring into a graphite mold placed in the chamber and heated to 700 - 900 ° C. After filling the form, its heating is turned off and the profitable part of the casting is heated by a defocused electron beam with a power of 15–30 kW. At the end of the casting process, the heating is turned off, while the beam power is gradually reduced to 0. The method provides an increase in the density of castings from 8.9 to 8.98 g / cm ³ , elimination of casting defects, reduction in machining volume by 4 times.

Description

The invention relates to metallurgy, in particular, to special methods for producing castings in electron-beam installations (EST), and can be used in the manufacture of cast-metal copper molds used for ECF, ESR and other water-cooled chill molds with a complex shaping surface.

The aim of the invention is to increase the density of castings and reduce the complexity of their manufacture.

In the proposed method for producing cast copper crystallizers, copper melted in an electron-beam installation is refined and poured into a graphite mold placed in a sealed chamber and heated to 700-900 ° C. After filling the form, its heating is turned off and the profitable part of the casting is heated by a defocused electron beam with a power of 15-30 kW. At the end of the casting process, the heating of the profits is turned off, while the beam power is gradually reduced; o 0.

Heating the mold to 700-900 ° C contributes to increasing its filling capacity by maintaining the metal's fluidity at a high level and obtaining

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cast surface of high-purity casting that does not require additional mechanical processing, which significantly reduces the complexity of their manufacture. Heating the mold to less than 700 ° C does not ensure the formation of thin sections of the casting, since the temperature of the metal that filled the mold decreases and its fluidity decreases, and defects form in the form of twists on the cast surface, while the mold is heated to a temperature above 900 ° C leads to local casting of the mold to the mold, especially in zones of thick sections, due to prolonged contact of the molten metal with the hot form. In addition, in the thick sections of the casting, loosening is formed due to an increase in the metal solidification time in these parts and the development of segregation and shrinkage processes 6

Heating the profitable part of the casting

defocused electron beam is used to create the most favorable conditions for crystallization and increase its density - one of the main criteria for the quality of crystallizers. The use of thermal energy of the defocused electron beam makes it possible to maintain the entire volume of the profitable part of the casting in the liquid state until it is completely solidified, which increases the efficiency of the profit and obtain the most dense casting. Heating is power controlled. The optimum power at which the most efficiently operating profit is 15-30 kW. With a power of less than 15 kW, the profit practically does not work, which is confirmed by a slight increase in density. With a capacity of more than 30 kW, the upper metal layers in the profitable part of the casting overheat, and the profit burns to the mold, which makes it difficult to extract and reuse the mold.

For example, a charge of copper waste is loaded into the crucible EVIL. At the same time, a form of graphite graphite is assembled, which is placed in the EVIL chamber and placed on the heating to

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700-900 C. The furnace chamber is sealed, a vacuum of 1-5 h.st. is created. The crucible is used to melt the charge, overheat and refine the copper, and then pour it into the mold. After the mold is cast, its heating is turned off and the profitable part of the casting is heated by a defocused electron beam with a power of 15-30 kW by distributing it over the entire profit surface. After complete casting, i.e. after 5–15 min, the heating gain is turned off, the power of the electron beam decreases to 0, and when the casting temperature reaches 200–300 ° C, the chamber is depressurized, disassembled and the casting crystallizer is released from the rods.

Made cast crystallizers for ECL, ESR and chill devices according to the parameters of the proposed method. The resulting molds have a high purity of working surfaces.

Comparative analysis of the tests shows that the proposed method of obtaining casting molds as compared to the known method provides an increase in the density of castings from 8.9 to 8.98 g / cm3, elimination of casting defects, a decrease in the machining volume by A, which significantly reduces manufacturing.

Claims (1)

Invention Formula A method for producing castings, predominantly copper crystallizers, comprising melting and refining copper in an electron-beam installation, pouring it into a mold and crystallizing, characterized in that, in graphite form, which is preheated to 700-900 ° C, and in the process of pouring and crystallization, the profitable part of the casting is heated with a defocused electron beam with a power of 15-30 kW.