RU2533579C1 - Electroslag furnace for production of hollow ingot - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: this furnace allows continuous variation of slag and metal temperature in casting mould at remelting of consumable metal electrodes. Besides it can vary oxygen and carbon concentration in metal and control the slag-metal interface level. It is equipped with the system to control the lever of penetration of said electrodes in casing mould slag-metal melt. Said system is connected to computer system with interface to allow the control over electrode remelting process in this furnace with allowance for said measured data. Note here that said electrodes can spin about their axes and have axial bores made along the full length. Said bores communicate said electrodes with deoxidiser and slag-forming loose material feed device pipes feeding said material into remelting zone.

EFFECT: production of high-quality hollow ESR steel ingots in controlled casting process.

2 cl, 2 dwg

Description

The invention relates to electrometallurgy and can be used in electroslag smelting of high-quality steel in furnaces [1, 2] by the ESR method during remelting [3] of consumable metal electrodes in a mold to produce [2] hollow or solid ingots (billets).

Known furnaces electroslag steelmaking [2, 3], in which the essence of the process of obtaining hollow cast ingots [2] is as follows. The technology of electroslag steel smelting [3] for hollow (solid) billets (ingots) requires the careful monitoring of the position of the cooled mandrel [1] relative to the smelted ingot using an automatic control system for electrofusion processes [2].

Steel smelting by the ESR method is carried out, for example, in a U-578 type furnace with its following design features [2]. The mold (17) and the pan (19) together with the table (20) on which they are installed are located on a special platform (1). The upper part of the ESR furnace consists of a column (8) fixed with its base (21) on a box-type bed (2), a trolley (6) of a mold, a trolley (9) of an electrode holder, electric drives (5) and (10), an electrode holder (13) , inventory head (14), table (20) with hydropneumatic actuator (3), pan (19), mold (17), receiving funnel (18), current source (11), short circuit (7), dispenser, furnace control equipment , air and water supply systems and ventilation systems. The lower part of the furnace [2] consists of a bed (2) fixed to the foundation (1), a caliper (22) inside, a mold (mandrel), a caliper drive mandrel (23) and the mandrel itself (16).

As consumable metal electrodes (15) for smelting hollow ingots in an ESR furnace, solid or hollow rods [2] of various diameters and configurations are used [1, 2]. Consumable electrodes (rods) in the working position are held by an inventory head (14) of a cassette type. The inventory head is clamped by a tick-shaped electrode holder (13), and the clamping mechanism of the electrodes is pneumohydraulic [2]. The mold, mandrel, pan on the U-578 furnace are cooled using a water supply system. The furnace of electroslag steel smelting (ESWS) operates on a liquid slag start. The liquid flux [1, 3], previously prepared at the flux-smelting unit, is poured into the crystallizer by a siphon method through a receiving funnel (18).

The melting current of ESWS is set by the operator manually or with the help of a setting software device [2] and is supported automatically with the help of CAP. Dorn (16), forming a cavity in a lost wax ingot, is made in the form of a truncated cone broadened in the lower part [1, 2]. During the melting process, the mandrels are moved down with the support (22) and its drive (23). In the process of ESWS, the movement of the mandrel is carried out automatically using the ATS. A dosing device is provided on the EShVS furnace [2], with the help of which a dosed amount of additional flux, deoxidants, alloying elements and other bulk materials can be fed to the slag bath.

ESW furnaces have [2, 3] the undoubted advantage that hollow ingots (billets) are melted in the ESW furnace by the filling method and therefore they have a smooth outer surface, and the mandrel is moved downward during melting, i.e. in the direction opposite to the direction of growth of the ingot, almost completely eliminates the formation of tears on its inner surface. The choice of the optimal composition of the main and additional flux for slag formation, optimization of deoxidizing agents and temperature conditions of smelting allows one to obtain ingots with a significant decrease in the sulfur concentration in the ESR metal, as well as with a low content of oxygen and non-metallic inclusions in the ingot.

Nevertheless, all of these [1] and other known models of furnaces [2, 3] of electroslag steel smelting by ESR method [3] have significant drawbacks, for example, in that the additional supply of slag-forming (fluxes), deoxidizing agents, alloying and other materials are carried out to the slag bath in the mold compactly [2] through the dispenser and funnel (18), i.e. without taking into account the temperature and viscosity state of the slag-metal melt, which does not provide uniform and fast dissolution of slag-forming mixtures (for example, lime), and CaO often clumps and dissolves for a long time in the slag. These shortcomings can be eliminated by using [4] temperature control sensors with ECE (electrochemical elements), which allow mea surement of the temperature of slag and metal in the crystallizer bath, determination of oxygen and other elements in the liquid metal along the course of melting in the EShVS furnace by ESR method, and also to find the position of the slag-metal interface with the determination of the amount of slag and metal in the EShVS furnace. It also seems possible to carry out [4] a continuous dispersed supply of slag-forming (fluxes) and other materials to the slag bath through axial holes in the consumable hollow electrodes of the ESR furnace. However, these technological methods in ESR furnaces [1, 2] are not used in practice [3].

The closest to the invention according to the technical essence and the result achieved is [5] an electroslag steel smelting furnace for producing hollow ingots by the ESR method, which allows melt reusable hollow metal electrodes on the main flux using additional flux and deoxidizers during the casting process . During remelting [5], the mold with the mandrel moves along the ingot as it is deposited towards the consumable consumable electrodes. On the hollow ingot from the outside and inside, a slag skull made of flux is formed. To compensate for the flux spent on the formation of the skull, an additional flux is added in portions to the slag bath through the batcher and funnel throughout the melting process, which does not dissolve uniformly, as in other [1, 2] known models of furnaces [3] electroslag remelting [5] .

The disadvantage of this known model of the furnace [5] electroslag steel smelting by ESR is the inability to obtain a hollow ingot with a height of more than 3 m, because the amount of flux decreases towards the end of the remelting, and the lime (CaO) crumbles and poorly dissolves in the slag and, in addition, the composition of the slag and its properties change, which affects the change in the properties and quality indicators of the smelted steel ingot.

The technical result of the invention is the creation of an ESW furnace for producing tube ingots of high quality of the required height with the same properties of a steel ingot over the entire height and cross-section, ensuring the optimum temperature and quality indicators of the composition of the slag and metal melt during the melting process.

The technical result is achieved as follows.

An electroslag furnace for producing a hollow ingot containing a tray for forming an ingot mounted on a bed, a mandrel with its cooling system, consumable metal electrodes, an electrode holder carriage, which can be vertically moved along the column as the electrodes melt, a carriage with a crystallizer with a slag-metal melt installed with the possibility of moving along the column towards the aforementioned electrodes, and a device with nozzles for supplying deoxidizers and slag-forming bulk materials, characterized in that it contains a temperature control sensor with an electrochemical cell (ECE), a computer system interface and a system for monitoring the level of penetration of the ends of the said electrodes into a mold with a slag metal melt, while the consumable metal electrodes are rotatable around its axis and with axial holes along the entire length, which are mechanically connected to the nozzles of the device for feeding deoxidizing agents and slag-forming bulk materials into the remelting zone the ends of said electrodes, and a computer system interface connected to the level control system burying the ends of said electrodes in the mold with the melt and a slag with a temperature control sensor output parameters with EHE mounted on the mold body.

The temperature control sensor with ECE is made with the possibility of vertical movement into the slag metal melt relative to the slag-metal interface during remelting of the ends of the said electrodes.

The temperature control sensor with ECE is placed parallel to the mentioned electrodes.

The computer system interface is connected to the output parameters of the temperature control sensor with an ECE with the possibility of fixing the position of the level of the slag-metal interface in the mold during remelting of the above electrodes.

This object is achieved by the fact that the invention provides an electroslag steel smelting furnace (ESWS) for producing tube ingots, including a water-cooled mandrel mold with a slag-metal melt, a sensor for temperature control with an electrochemical cell (ECE), a computer system with an interface, consumable metal hollow electrodes and a device with nozzles for feeding flux and other bulk materials into the slag melt of the mold, and the ESW furnace in this case differs in that we expend hollow rotating metal electrodes are made with axial holes and are mechanically connected to the nozzles of the device for supplying fluxes, deoxidants and other bulk materials to the end slag remelting zone, the interface of the computer system being connected to temperature control sensors with ECE and, in addition, the ESW furnace is also different the fact that in the mold body the temperature control sensor with ECE is placed in the liquid metal parallel to the electrodes and vertically to the surface of the slag metal melt and, in addition to this oh, the ESWS furnace is also characterized in that the computer system is connected to a mechanism for controlling the level of lowering of the consumable metal rotating hollow electrodes into the mold with slag melt, and the furnace is also characterized in that the elements of the computer system are functionally fixed and connected to the output parameters of the temperature control sensor with ECE with the possibility of fixing the position of the level of the boundary of the slag-metal in the mold during remelting of the consumable electrodes.

A general view of the design of the proposed ESWS furnace is shown in figures 1 and 2, and the features of its operation are as follows. General view of the furnace (Fig. 1) includes a foundation (1) with a bed (2) and a pallet, which shows an ingot (3) formed during cooling in the mold (5) and the mandrel (4). Slag-metal melt (6) in the mold (5) is formed as a result of melting of consumable metal hollow electrodes (9), which are fixed on the electrode holder (10). The shoulder (7) constructively connects and supports equipment (mold and mandrel), and also includes inlet and outlet pipes of the mandrel cooling system. The conductor (8) serves as a guide for the electrodes immersed in the mold, and also performs the function of equalizing the current on the electrodes. Voltage and current from the furnace transformer are supplied to the electrodes through the electrode holder, which are moved vertically with the help of the carriage (11). The liquid metal formed in slag (6) is cooled and crystallized on the surfaces of the mandrel (4) and crystallizer (5) due to the influence of the cooling systems of the mandrel (12) and crystallizer (13) with the formation of an ingot. As the electrodes melt, the mold carriage (14) moves along the column (15) towards the electrodes rotating around their axis. For continuous measurement of temperature and other melting parameters, temperature sensors (16) with electrochemical elements (ECE) are installed in the mold (5). Information from the sensors enters the computer control system (ATS) and process control ESWS. Information from sensors, i.e. the temperature of the metal and slag in the mold, the activity (concentration) of oxygen and carbon in the metal, the position of the slag-metal interface, the determination of the weight of the metal and slag in the slag melt, is used to ensure effective process control in the proposed model of the ESW furnace, which differs significantly from the prototype [5].

The schematic diagram of the ESW furnace, in which the proposed method is implemented, is supplemented and presented in figure 2. The furnace includes a pan (2), liquid metal and a formed ingot (3), liquid slag (6) in a mold (5), in which temperature sensors with ECE are installed (16). A water-cooled mandrel (4) and a mold are used to form an ingot as the consumable rotary hollow metal electrodes are melted (9). In this case, the electrodes are moved using a carriage with an electrode holder (10), and through the axial holes of the electrodes, slag-forming mixtures (fluxes), deoxidants and other bulk materials are continuously fed into the high-temperature zone of melting of the ends of the electrodes (23) using a device (17) ), which is connected to the electrodes by means of a pipe (18) with supply hoses. In the circuit of the ESR furnace (Figs. 1 and 2), a system (19) is used to control the level of deepening of the electrodes in the mold as the ends of the electrodes melt in the zone of the electric field (arc). The voltage and arc current are provided by the transformer (20) of the furnace. The interface (21) of the computer system (22) is functionally fixed with the output parameters of the temperature control sensor with ECE with the provision of monitoring the position of the level of the slag-metal interface during electroplating of the electrodes in the furnace.

Analysis of the experience of using [1, 2] the operation of ESR furnaces [3, 5] using [4] new technical developments indicates the possibility of increasing the efficiency and prospects of using the proposed invention to improve the technology for producing tube ingots.

BIBLIOGRAPHY

1) Latash Yu.V., Medovar B.I. Electroslag remelting. M: Metallurgy, 1970 - 240 p.

2) Medovar B.I., Stupak S.M. Electroslag furnaces. Kiev: Naukova Dumka Publishing House, 1976 - 415 p.

3) Linchevsky B.V., Rigina L.G., Takhirov A.A. Electrometallurgy No. 9, 2012. - p. 7-10.

4) Merker E.E. and other RF Patent No. 2374582 of 11/27/2009. Publ. Bull. No. 33; RF patent No. 2360009 of 11/27/2009. Publ. Bull. Number 18. Determination of the interface between the slag-metal phases by the electrochemical method. Factory Laboratory No. 12, 1976 - p. 1491-1493.

5) Pavlova N.P., Demidov V.A., Polovkin V.N. A method of obtaining hollow ingots by ESR. RF patent No. (11) 2363743 dated 02/20/2009 according to the application No. 2007130099/02 dated 08/06/2007.

Claims (2)

1. An electroslag furnace for producing a hollow ingot, comprising a tray for forming an ingot mounted on a bed, a mandrel with its cooling system, consumable metal electrodes, an electrode holder carriage installed with the possibility of vertical movement along the column as the electrodes melt, a carriage with a crystallizer with slag metal melt installed with the possibility of moving along the column towards the aforementioned electrodes, and a device for supplying deoxidizers and slag-forming bulk m materials with nozzles, characterized in that it is made with the possibility of continuous measurement along the remelting of the consumable metal electrodes of the temperature of the slag and metal in the mold, the concentration of oxygen and carbon in the metal and monitoring the position of the level of the slag-metal interface, and is equipped with a system for controlling the level of deepening of the ends the mentioned electrodes into a slag-metal melt in a mold associated with a computer system with an interface providing control of the process of remelting the electrodes in leakage taking into account the aforementioned measured data, while the consumable metal electrodes are made to rotate around its axis and with axial holes along the entire length, through which they are connected to the nozzles of the device for supplying deoxidizing and slag-forming bulk materials into the remelting zone of the ends of the said electrodes. 2. The furnace according to claim 1, characterized in that it is equipped with temperature control sensors and a device for fixing the position of the level of the slag-metal interface in the mold, while the elements of the computer system are functionally connected to the output parameters of the said sensors and device.

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