SU697252A1 - Method of treating melt in units for low-pressure casting - Google Patents

Description

(54) METHOD FOR TREATING MELT IN CASTING INSTALLATIONS UNDER LOW PRESSURE

For this purpose, the purge is carried out cyclically with the flow of refining in the cycle of the purge and modifying the additives on the metal mirror into the metal line.

Cyclic purging of the liquid metal with an inert gas with refining and modifying additives in each purging cycle to the metal mirror in the metal conduit makes it possible: to reduce the refining time due to the intensive mixing of the refined metal in the crucible and the joint processing of the melt with an inert gas and refining additives; to modify the melt in the crucible of the .4l unit to be cast under low pressure during the production of castings and to improve the physical and mechanical properties of the castings; reduce the consumption of additives due to the uniform supply of additives to the melt in small portions, which are displaced from the metal conductor, through the melt in the crucible from the bottom upwards and absorbed by the melt before reaching the surface, which eliminates burnout; reduce the consumption of inert gas by reducing the duration of refining.

In the process of producing castings in an installation, under low pressure, the molten metal is contaminated with oxide films, nonmetallic inclusions, and other materials, which are formed by the interaction of the molten metal with the material of the conductor and crucibles. Therefore, before filling the mold with a liquid metal, the liquid metal in the crucible and metal conduit is purged with an inert gas under pressure exceeding the hydrostatic pressure of the metal in the crucible, with a frequency of 5-10 cycles per minute, with refining and modifying additives being fed to the metal mirror in the metal conduit before each cycle. . In each purge cycle, the refining and modifying additives are displaced from the pipeline, pass through the melt in the crucible from the bottom up, and are absorbed by the melt before reaching the surface of the melt, which eliminates burnout. In addition, the inert gas from the bottom of the metal pipe goes up and additionally cleans the metal in the crucible from oxide captivity and other zag;

Cyclic purging of the liquid metal with an inert gas with the supply of refining additives to the metal in the metal conduit in each purging cycle reduces the refining time due to the intensive mixing of the refined metal in the crucible and the joint treatment of the melt with an inert gas and through the flow of syrup and in the crucible. .20%,.

Cyclic purging of the liquid metal with an inert gas, with the supply of metal in the metal pipeline in each cycle of purging to the mirror, simultaneously with refining modifying additives, allows modifying the diffusion in the crucible of the installation during the production of castings and improve the mechanical properties of the castings by 10-15%. In this method of treating the melt, the consumption of inert gas and additives is minimal due to the reduction in the duration of refining and the uniform supply of additives to the melt in small portions, which are displaced from the metal pipe, pass through the melt in the crucible from the bottom up, and are absorbed by the melt before reaching the surface of the melt, which eliminates burnout. The technology for casting the part below shows the housing of an aluminum alloy aluminum alloy pump. A liquid metal is supplied at an adjustable overpressure, varying from 0 to 0.25 atm, from a crucible cast under low pressure through a metal conduit into a mold having a temperature of 200 C. After filling the mold with liquid metal, cutting off with simultaneous sealing of the metal conductor and dumping the excess pressure above the metal mirror in the crucible of the installation to be cast under low pressure. In this case, the metal is contaminated with oxide films and non-metallic inclusions, which are formed by the interaction of the liquid metal with the material of the metal wire and crucible. Then, refining additives of manganese chloride in the amount of 0.018% by weight of the mixture, modifying additives of fluoride and sodium chloride salts in the amount of 0.23% by weight of the mixture, in a proportion of 2/3 parts fluoride and 1/3 hours, are supplied to the metal mirror in the metalworking line. chloride salts and inert gas - argon under pressure, increasing from 0 to 0.3 atm. Under the action of excess pressure on the metal mirror in the metal conduit, the refining and modifying additives with liquid metal from the metal conductor are forced downward and enter the crucible of the installation, where they are fully absorbed, and, in addition, argon from the lower part of the metal conduit rises up and further purifies the metal crucible from oxide captivity and non-metallic inclusions. The refining and modifying additives in the amounts indicated above and the inert gas are fed at a frequency of 5 cycles per minute for 2 minutes. After the refining and modification has been completed, the metal from the metal conduit is opened into the mold and filled with liquid metal. 5 WA excess regulated pressure above the metal mirror in the crucible of the installation to be cast under low pressure. The metal entering the mold has been refined, cleaned of oxide captivity and other contaminants and modified, which helps to obtain high-quality castings.

The application of the invention allows to improve the mechanical properties (tensile strength) of castings 5 by 10-15% and to increase the productivity of the process by 20%.

According to the experimental data from the implementation of the proposed invention, the economic efficiency at the 20 Kirovograd plant of tractor hydraulic units amounts to 100 thousand rubles. in year.

Claims (2)

1. US patent 3469740, cl. In 22 D 27/14, 1970. 2. USSR author's certificate for application number 2491974/02, cl. On 22 D 17/00, 1977.