RU2093768C1 - Combination vacuum induction electron beam furnace for melting, refining and castiny of metal - Google Patents

Abstract

FIELD: metallurgy. SUBSTANCE: surface is provided with additional induction chamber connected with electron beam chamber by means of spout and vacuum seal. Induction chambers are made in form of rotary batch furnaces; spouts are heated and are mounted for motion along axis of turn of batch furnaces for transfer of metal; refining hearth of electron beam chamber is made in form of funnel with guide groove spirally lowering from periphery to center and terminating in system of holes located over perimeter around central hole for electron beam in course of casting simultaneously for heating the metal in crystallizer or ingot mould for bringing up the pipe into the sinkhead; heating sources and evacuation systems are self-contained for each chamber. EFFECT: enhanced reliability. 3 cl, 1 dwg

Description

 This proposal relates to vacuum metallurgy, in particular, to designs of vacuum smelting and refining furnaces for the smelting of ferrous, non-ferrous and other metals, for example, copper.

 It is known that for vacuum smelting of copper for critical purposes (for electronics, nuclear energy, rocket science and the chemical industry), IMV-0.16 PI induction furnaces are used. MO1, OKB-891 and electron beam type EMO-200 (former GDR) (see "Fundamentals of Metallurgy", Volume VII, publishing house "Metallurgy", 1975, under the editorship of A.I. Strichin, A.I. Basov, p. 836).

 The induction remelting of copper in IMVO-0.16 PI MO1 industrial vacuum furnaces (ISV-0.16 PI M01) since 1969 makes it possible to obtain cast vacuum-tight copper for the mentioned purposes from cathodes with unlimited dendriticity, oxidation and gas content and melting and rolling speeds press production.

 But with vacuum induction melting in IMVO-0.16 (IS-0.16) furnaces, the achieved yield does not exceed 70% of the weight of the remelted charge, and copper alloys with highly reactive alloying elements chromium, zirconium, collection, etc. are contaminated with non-metallic inclusions from crucible materials, which, without surfacing on the surface of the melt, with the existing casting method, pass into the body of the ingot. The working vacuum in induction furnaces does not exceed 5-10 mm Hg. Art.

Electron beam remelting of cathode copper on furnaces EMO-200 is characterized by low technical and economic indicators:
a) loss of metal with carts and condensate in combination with irrevocable amounts to 15%
b) the specific productivity does not exceed 40-65 kg / h with an installed capacity of the furnace 400 kW;
c) the possibility of using the turns of smelting and processing ingots and other types of raw materials is excluded, except for dendritic copper cathodes of high purity electrolytic refining of the MOO grade in accordance with GOST 5.1.67 and MOA;
d) the structure of cast electron-beam copper is columnar, dendritic, leading to anisotropy of mechanical properties in semi-finished products;
e) the absence of copper oxide in cast vacuum-melted copper is not guaranteed, which is the cause of the "hydrogen" disease in semi-finished products;
f) the possibility of smelting high-quality alloys with a uniform chemical composition is excluded.

 Thus, for the reasons stated, typical vacuum furnaces used for the production of high-purity copper and heat-resistant copper alloys for electric vacuum devices and nuclear power are not optimal melting units.

 It has also been practically established that to obtain a high-quality cast structure of copper alloys with a temperature range of crystallization, the duplex process is optimal: induction melting of the feedstock, which ensures the use of various types of charge and uniformity of chemical composition, followed by remelting of the obtained ingot billets in arc and electron beam furnaces.

 Discrete duplex processes VIP-ELP, VIP-VDP are widely used in high-quality and special metallurgy.

 Common disadvantages of discrete duplex processes are low productivity, high energy intensity, labor intensity, redistribution time, low yield (for binary alloys MN-45, MN-19, the usable yield does not exceed 50%, etc., which puts these alloys among unprofitable).

 Based on the volumes and specifics of the production of vacuum copper and copper alloys, the most economical among typical operating furnaces are vacuum ovens with a capacity of 300-600 kg with the possibility of casting metal into ingots of various weights, and the most promising combined vacuum plants that allow the use of various heating sources for melting (see . "Vacuum melting of copper and its alloys." Edition TsNII and TEI TSM MCM, Moscow, 1974, p. 78).

 The aim of the present invention is the creation of a combined induction-electron-beam melting and refining furnace, combining the advantages of these types of furnaces and providing a discrete process of melting and semi-continuous casting while improving the quality of the resulting metal.

 An analogue of the present invention can be a working combined refining furnace СРР-10t, of the firm "Airco Vacuum Metals Division" in Berkeley, California, USA, used for the production of the most expensive stainless and high-strength steels, with a capacity of 5 tons of steel / hour.

 ". The combined refining process carried out in CPP-10t combines the advantages of induction melting (low metal cost, good uniformity), vacuum arc or electroslag melting (removal of non-metallic inclusions and obtaining a good cast metal structure) and electron beam melting (long-term exposure to deep metal vacuum for ultra-deep refining, the almost complete removal of non-metallic inclusions and a convenient way to heat the ingot profit during continuous casting). " (See "Combined Vacuum Induction and Electron Beam Furnaces for Steel Refining and Casting." Zant A. Sith, G.R. Coad, V.K. in the book "Vacuum Metallurgy", trans. From English, M. 1973, p. 143 )

 However, the CPR-10t combined refining furnace used for steel refining cannot be used for copper refining, since it is not applicable for the production of small volumes of alloys and a wide range of grades, and the developed surface of water-cooled copper hearths with an area of more than 5 square meters. m leads to unreasonably high losses of copper by evaporation in a deep vacuum, amounting to 200 kg / h (at 1400 deg. C, the vapor pressure of copper is above 0.1 mm Hg and evaporation will be 1.13 • 10 g / cm • s) and large heat losses due to the high thermal conductivity of copper and water-cooled copper refining hearths.

 Based on the above analysis of existing melting and refining furnaces and recommended for the future, in our opinion, the proposed installation can satisfy the basic requirement.

 The combined refining unit (drawing) consists of two coreless induction vacuum furnaces (1) of a rotary type periodic operation without molds installed on the opposite sides of the electron beam furnace (2) with an axial type electronic heating source (3) and connected with a vacuum furnace by vacuum shutters ( 4). Each of the furnaces has autonomous vacuum systems (5).

 To transfer liquid metal from crucibles (9) of induction furnaces (1) to electron beam refining and subsequent crystallization, mobile resistance-heated overflow gutters (6) are used.

 For deep refining of the melt in the electron beam furnace directly above the mold (7), a general refining underneath (8) is installed with a guide chute spiraling down to the center and ending with drain holes for releasing metal into the mold (mold). In the center of the refining hearth a hole was made for heating with an electron beam in the mold.

 For honey, refining under graphite, for steel, cooled copper, with a skull. Crucibles of induction furnaces, respectively, graphite and printed from electrofused refractories.

 As a basic design for creating a compact combined induction-electron-beam furnace, the modernized IMV-0.16 PI (ISV-0.16 PI) furnace with a capacity of 100 kW, a copper crucible capacity of 350 kg and an electron beam electron beam furnace, developed over many years, can be adopted -1 design of the MEP with a capacity of 200 kW, having mechanisms and devices for producing an ingot with dimensions: 300 diameter, 2000 mm long and weighing up to 1200 kg or PEL-1000 design VILSa.

 On the proposed combined induction-electron-beam furnace, the metal is refined as follows (with reference to copper and its alloys).

 In a preheated crucible (9) of the induction furnace (1) in atmospheric conditions, liquid filling of the oxidized charge is carried out to its maximum capacity.

 Next, the furnace (1) is vacuumized to 1-0.1 mm Hg, and the metal is heated to 1400-1450 degrees. C. With increasing temperature, the oxidized copper melt is reduced by solid carbon of the crucible lining, accompanied by spontaneous purging with carbon monoxide bubbles CO.

 By the end of boiling of the melt and reaching the required temperature of 1400-1450 degrees. C metal is practically refined and ready for alloying, if necessary, and additional deep refining with an electron beam and subsequent crystallization.

 When the metal is ready in the induction furnace (1), open the shutter (4) between the induction (1) and electron beam furnaces (2) and move the preheated trough (6) to transfer the melt by overflow from the crucible (9) of the induction furnace (1) to the refining (8) electron beam furnace (2).

 Then produce a slow adjustable overflow of metal from the crucible. Flowing in a thin layer along the spiral groove of the hearth from the periphery to the center, the melt is further refined by an electron beam (10) and, upon reaching the system of calibration holes, flows to crystallization in the mold (7) during casting by the filling method or into the mold during casting by the semicontinuous method.

 At the end of the discharge of metal from one induction furnace, the emptied furnace is cut off from the electron beam shutter (4) between them and prepared for the next fore-vacuum melting or refining of the oxidized melt.

 In the same sequence, drain from the second induction furnace. If necessary, 3-4 or more heats from induction furnaces (1) can be merged into one ingot (11). The diameter of the ingot can be from 100 to 300 mm. The profit in the mold (7) in the period between drains and at their ends is heated by an electron beam, maintaining the upper layer in a molten state, which eliminates shrinkage defects.

 After the shrinkage shell is removed, the ingot with the ingot mold is lowered into the ingot chamber (12), the shutter (13) is closed between the refining chamber and the ingot chamber.

 10-15 minutes after the end of the discharge, the chamber of the ingots will be evacuated, disconnected from the electron beam furnace and removed to remove the ingot.

 At the end of the unloading of the ingot, the mold is prepared (cleaning, lubricating, heating, introducing the seed) and fed with the ingot chamber for fastening with the refining chamber of the electron beam furnace for crystallization of the next ingot.

 The performance of the combined copper plant using liquid filling will be about 6 tons of rough ingots per day. The expected yield is not less than 85-90%. Crucible resistance 90 melts.

 When using solid filling, the productivity will be 4.5 tons / day of rough ingots. The resistance of crucibles is 40-60 heats.

 Combined induction electron beam furnace for melting, refining and casting metal in vacuum, characterized in that in order to provide discrete melting and preliminary refining and subsequent semi-continuous deep refining and casting, it has diametrically connected laterally to the electron beam furnace with a coaxial axial electronic source metal heating and a cooled crystallizer two rotary induction furnaces of periodic action with heated overflow chutes, alternating moving along the axis of rotation of induction furnaces.

 The combined induction electron beam furnace according to claim 1, characterized in that, in order to increase the residence time of the melt in the electron beam refining zone, it has a refining channel with a guide chute that spirals down to the center and ends with a calibration drain hole system for raining the refined metal into the mold, and a central hole for heating the ingot arrived in the mold.

Claims (3)

 1. Combined vacuum induction-electron-beam furnace for melting, refining and casting metal, containing induction and electron-beam chambers connected by overflow chute and vacuum shutter, refining underneath, located in the electron-beam chamber, molds, heating sources and pumping system, characterized in that it is equipped with an additional induction chamber connected to the electron beam chamber by an overflow trough and a vacuum shutter, while the induction chambers are enes as a rotary kiln type batch and overflow troughs made heated and movably mounted on the pivot axis of induction furnaces for metal overflow.  2. The furnace according to claim 1, characterized in that the refining under the electron beam chamber is made in the form of a funnel with a guide groove spiraling lowering from the periphery to the center and ending with a system of drain holes located around the perimeter around a central non-flood hole for the electron beam guided in the process of pouring simultaneously for heating the metal in the mold or mold and removing the shrink shell.  3. The furnace according to claim 1, characterized in that the heating sources and pumping systems of each process chamber are autonomous.