US3732915A

US3732915A - Vacuum arc furnace

Info

Publication number: US3732915A
Application number: US00187271A
Authority: US
Inventors: A Lugovoi; G Kharatian; B Izraelson; V Kvashnina
Original assignee: Individual
Current assignee: Individual
Priority date: 1971-10-07
Filing date: 1971-10-07
Publication date: 1973-05-15
Anticipated expiration: 1990-05-15

Abstract

A furnace for consecutive primary melting and secondary remelting is fitted with a cooler and an ingot withdrawal gear mounted on a supporting swing column and has a changeable mould with a stationary base plate for the secondary remelting of metal; the mould is set up on the said column instead of the cooler and the ingot withdrawal gear.

Description

United States Patent 1 Lugovoi et al.

[ 11 3,732,915 1 May 15, 1973 i541 IVACUUM ARC FURNACE Inventors: Anatoly 1 Ivanovich Lugovoi, 4 Minaevsky proezd, 6, kv. I, Moscow; Grigory Alexandrovich Kharatian, Khotkovo, ulitsa Lenina, 4, kv. l3, Moskovskaya oblast;

' Boris Izidorovich Izraelson, Junykh Lenintsev, 92, kv. 49; Vera Nikolaevna Kvashnina, Dmitrovskoe shosse, 7/2, kv. 127, both of Moscow, all of U.S.S.R.

22 Filed: Oct.7, 1971 21 Appl.No.: 187,271

52 U.S.Cl ..164/252 51 lnt.Cl. ..B22d 27/02 Field of Search ..164/50, 52, 250, 7 164/252; 13/9 [56] References Cited UNITED STATES PATENTS 3,190,949 6/1965 Gruber et al. 1 3/31 3,235,373 2/1966 Poole et al ..75/10 3,341,321 9/1967 Morrison et al. ..75/l2 3,523,995 8/1970 Tulin et al. ..l64/252 FOREIGN PATENTS OR APPLICATIONS 1,200,278 7/1970 Great Britain 1 64/252 Primary ExaminerJ. Spencer Overholser Assistant Examiner-John E. Roethel A ttorney- Holman & Stern 57] ABSTRACT A furnace for consecutive primary melting and secondary remelting is fitted with a cooler and an ingot withdrawal gear mounted on a supporting swing columnand has a changeable mould with a stationary base plate for the secondary remelting of metal; the mould is set up on the said column instead of the cooler and the ingot withdrawal gear.

1 Claim, 2 Drawing Figures VACUUM ARC FURNACE BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the field of metal lurgy, more particularly to electric arc furnaces for melting metals and their alloys.

2. Description of the Prior Art For the production of high-grade metals andtheir alloys arc melting under vacuum is used.

Widely known is a vacuum arc furnace for melting ingots by smelting a consumable electrode.

The above said furnace incorporates a melting chamber with an. rod-electrode holder inverted in it, a mould adjacent to the chamber and fitted with a movable base plate under which are located a cooler and an ingot withdrawal gear overhung from a supporting column and capable of travelling vertically, all the aforesaid components disposedin an air-tight furnace shell.

The furnace serves for the primary remelting of the electrode, made from pressed (of the comminuted ore with requisite additions) zirconium, to produce an ingot for the secondary remelting process.

In order to improve pumping conditions when venting and removing gases copiously liberated during melting the melting zone of the foregoing furnace is arranged close to a connecting vacuum system.

As the ingot is built up, the ingot withdrawal gear transfers it into the cooler.

Secondary remelting of the ingot formed is effected in a separate vacuum arc furnace having a mould with a stationary base plate.

Hence for producing a commercial ingot the shop shall be equipped with two furnaces: one for primary and another for secondary remelting.

However, the use of two furnaces is not justified in all cases, especially for the small-lot production of ingots.

In practice there is the need for carrying both the first and the second remelting operations in a single furnace which would ensure a saving in the area of the production floor, and ensure more efficient usage of standard equipment and a reduction in readiness time in the course of production.

SUMMARY OF THE INVENTION It is an object of the present invention to develop a construction of an electric furnace which would enable both the primary and secondary remelting operations to be accomplished in it.

According to the specified and other objects in a vacuum arc furnace incorporating the invention the following elements are set up in an air-tight furnace shell: a melting chamber with a rod-electrode holder inserted in the chamber, a mould adjacent to said chamber and having a movable base plate under which are mounted a cooler and an ingot withdrawal gear overhanging from a supporting column and capable of shifting verti cally; in accordance with this invention, the supporting column is'free to swing about its axis and is suited for the removal ofboth the color and the ingot withdrawal gear when they are positioned by the column rotation on .a discharging axis and a changeable mould is provided fitted with a stationary base plate and intended for the second remelting of the metal, with the mould overhanging from the said column to replace the mould equipped with the movable base plate, the cooler and the ingot withdrawal gear.

The changeable units and gears as well as the use of a column for ingot discharging will'permit both the first and the-second remelting operations to be carried out in one and the same furnace.

BRIEF DESCRIPTION 01% THE DRAWING Described below is an exemplary embodiment of the invention to be considered with reference to the accompanying drawings, in which:

FIG. 1 depicts a side view of a vacuum arc furnace, conforming to the invention, with a mould and a movable base plate; I

FIG. 2 is a vertical section through the axis of a furnace fitted with amould and a stationary base plate.

A furnace incorporates protective shell 1 (FIG. 1) of a welded construction made from rolled section and sheet steel and fitted with enclosed platforms (not shown in the drawing) for furnace attendance.

Located within the shell is melting chamber 2 which is a welded water-cooled cylindrical casing with an interior made of two-layer steel.

Melting'chamber 2 communicates with a vacuum system 3 (FIG. 2).

Through the upper portion of melting chamber 2 is passed a holder 4 to a rod-electrode linked with rod travelling gear 5.

Travelling gear 5 of rod-electric holder 4 is made as a single screw enclosed in the rod and operated by drive 6 with a differential reducing gear.

Travelling gear 5 of rod-electrode holder 4 ensures positive forced travel of the electrode.

Butting against the lower part of melting chamber 2 is mould 7 fitted with a movable base plate and made up of a copper flanged mould mounted in a steel case with a solenoid. For adjusting the level of liquid metal around mould 7 are positioned level gages (not shown in the drawing).

As the ingot is progressively built-up the movable base plate of mould 7 is shifted by ingot withdrawal gear 8 into cooler 9; v

The latter consists of two cylindrical shells with a cavity between them designed for cooling water circulation.

Mould 7 and cooler 9 overhung from carriage 10 are 1 free to move vertically along supporting column 11 made from a steel tube. v

For carrying out the second remelting, cooler 9 and ingot withdrawal gear 8 are stripped and replaced by changeable mould l3 equipped with .a stationary base plate and a bracket 12 fixed on supporting column 11.

Mould 13 withthe stationary base plate comprises a copper flanged mould installed in a non-magnetic steel case and fitted with a solenoid wound around its exterior and intended for stabilizing arcing.

The base plate of mould 13 is produced in the form of a stampedcopper sleeve anda steel bottom forming a cavity for cooling purposes.

In the lower part of column 111 is located swinging gear 14 of column 11' which serves for rotating said column about its axis and assures the discharge of the ingot produced.

Swinging gear 14 ismade up ofa hydraulic cylinder mounted at thebase of column 11 with a rod mechanically linkedwith a shackle (not shown in the drawing) provided at the base of column 11.

The furnacemay be provided with a mould cleaning device constituted 'by a steel pillar with arranged thereon brushes and operated by a hydraulic cylinder and a drive.

An electric circuit of the furnace provides for remote control of the furnace gears, for automatic or manual control of the melting process, there is also an alarm and interlocking system.

The setup functions as follows.

For producing an ingot by primary remelting vacuum melting chamber 2 is connected to mould 7 with a movable base plate.

By swinging'column 11 about its axis, the cooler 9 with ingot withdrawal gear 8 is moved outside protective shell 1. Then an electrode is lowered in cooler 9 with the aid of a shop crane and by rotating column 11 in the opposite direction both the cooler 9 together with the electrode and ingot withdrawal gear 8 are returned to their initial position in shell 1 and set up under mould 7, fitted with the movable base plate, coaxially with the mould.

Next, by shifting carriage 10, the cooler 9 is raised until it butts against mould 7.

The electrode is connected to the rod-electrode holder 4, whereupon the rod travelling gear 5 of rodelectrode holder 4 suspends the electrode in melting chamber 2. Now a door of the protective shell 1 is closed.

On forcing cooler 9 tightly against mould 7 the furnace is evacuated after which power is fed to strike an arc.

As the ingot is built-up, ingot withdrawal gear 8 transfers it into cooler 9. When the melting process is completed, the ingot which is chilled in cooler 9, is moved to the discharging axis where the hydraulic cylinder of ingot withdrawal gear 8 pulls it from cooler 9, whereupon it is handled by a shop crane to a point where further processing will occur.

When using the furnace for the secondary remelting operation, the ingot produced is not discharged but connected instead to rod-electrode holder 4 (FIG. 2) to be suspended in melting chamber 2. Next, the mould 7 with the movable base plate is detached from the melting chamber, cooler 9 and ingot withdrawal gear 8 arestripped from carriage 10 and replaced by mould 13 with the stationary base plate which is overhung from the carriage.

By swinging column 11, the mould 13 is positioned coaxially with melting chamber 2, after which carriage 10 raises it to butt against the chamber. A tightening gear (not shown in the drawing) of mould 13 is coupled to melting chamber 2.

Then the door of protective shell 1 is closed and the furnace evacuated.

Following this step, power is supplied to strike an arc. Flashing off in the arc the electrode (the ingot produced after first remelting) builds up a second remelting ingot into mould 13.

The melting process completed, power is switched off to extinguish the arc.

When the ingot which is produced in mould 13 with the stationary base plate, is cooled in vacuum (or in an inert atmosphere), air is admitted into the furnace. Mould 13 with the ingot contained therein is carried off melting chamber 2 with the aid of carriage 10 (after disconnecting the tightening gear). The door (not shown in the drawing) if the protective shell 1 is then opened. By swinging column 11 the mould 13 is positioned on the discharging axis where the base plate is detached from mould 13, the cylindrical portion of the mould is taken off and the ingot built-up which is supported on the base plate is handled by the shop crane for further processing.

The herein proposed construction of a vacuum arc furnace enables both the first and the second melting operations to be carried out in one and the same furnace, and ensures a saving in production area, effective usage of standard equipment and an increase in yield of the operating furnaces.

What is claimed is:

l. A vacuum arc furnace for consecutive primary melting and secondary remelting, comprising the following elements located in an air-tight shell: a melting chamber; a rod-electrode holder lowered from above into the said melting chamber; a first mould with a movable base plate butting against said melting chamber and used for primary melting for forming an ingot from molten metal; a cooler disposed under said first mould and disposed overhangingly to move vertically along a supporting column having means to cause axial rotation thereof and to strip and disengage said cooler from said column; a replaceable ingot withdrawal gear, disposed overhangingly of said column and capable of travelling vertically along the said column; a replaceable second mould having a stationary base plate overhanging to be free to move in a vertical direction along said column under the said melting chamber, said replaceable second mould being used in place of said first mould and for secondary melting.

Claims

1. A vacuum arc furnace for consecutive primary melting and secondary remelting, comprising the following elements located in an air-tight shell: a melting chamber; a rod-electrode holder lowered from above into the said melting chamber; a first mould with a movable base plate butting against said melting chamber and used for primary melting for forming an ingot from molten metal; a cooler disposed under said first mould and disposed overhangingly to move vertically along a supporting column having means to cause axial rotation thereof and to strip and disengage said cooler from said column; a replaceable ingot withdrawal gear, disposed overhangingly of said column and capable of travelling vertically along the said column; a replaceable second mould having a stationary base plate overhanging to be free to move in a vertical direction along said column under the said melting chamber, said replaceable second mould being used in place of said first mould and for secondary melting.