RU2239757C1 - Vacuum electric-arc melting furnace - Google Patents

Abstract

FIELD: vacuum metallurgy; melting furnaces for production of cast and shaped castings from high-melting and chemically active metals and alloys.

SUBSTANCE: proposed furnace has working vacuum chamber with water cooling system, lining slag crucible located in working chamber, consumable electrode feed mechanism mounted above lining slag crucible in one vertical axis, two side centrifugal tables and stand for welding the consumable electrode. Furnace is additionally provided with central centrifugal table located between two side centrifugal tables, second lining slag crucible and consumable electrode feed mechanism mounted above second lining slag crucible in one vertical axis. Lining slag crucibles and consumable electrode feed mechanisms are located in parallel and symmetrically relative to vertical axis of centrifugal table.

EFFECT: possibility of obtaining heavy castings, up to 600 kg by molten metal; ease in service; enhanced economical efficiency.

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Description

The invention relates to vacuum metallurgy, and in particular to smelting furnaces designed to produce cast and shaped castings from refractory and chemically active metals and alloys.

The closest analogue to the proposed installation is a vacuum melting and casting unit for melting and producing castings from titanium alloys with liquid metal smelting using the arc melting method with a consumable electrode in a skull crucible and centrifugal casting in DVL-250 casting molds (see Production of shaped castings from titanium alloys Bratukhin A.G., Bibikov E.L., Glazunov S.G. et al. - 2nd ed., revised and enlarged - M .: VILS, 1998. - Pages 45-46).

The DVL-250 smelting and filling installation consists of a working chamber, a vacuum system, a water cooling system, a graphite skull crucible, a feeding mechanism for a sacrificial electrode, two centrifugal tables and a separate stand for welding of a consumable electrode.

The electrode feed mechanism is mounted on a separate structure, which is rotated 180 ° to transfer the electrode from the welding stand to the working chamber. The casting of metal from a graphite skull crucible into containers of molds mounted on centrifugal tables is carried out on two opposite sides. The diameter of the centrifugal table is 1380 mm, the rotation speed is 200-400 rpm.

The considered melting and casting plant has the following disadvantages: it does not allow to obtain massive titanium castings weighing more than 300 kg and consumes a relatively large amount of electricity, which is one of the reasons for the high cost of titanium casting.

The objective of the invention is the creation of a vacuum smelting and casting plant, which enables the production of solid castings (up to 600 kg of molten metal), while increasing the productivity of a vacuum smelting and casting plant and reducing the cost of the resulting castings.

The essence of the invention lies in the fact that a vacuum arc melting and casting installation containing a vacuum working chamber with a water cooling system, a skull crucible placed in the working chamber, a consumable electrode feed mechanism mounted above the skull crucible on the same vertical axis, two side centrifugal tables and the stand for welding the consumable electrode is additionally equipped with a central centrifugal table located between two side centrifugal tables, a second skull plate and fur a sacrificial electrode feed mechanism mounted above the second skull crucible on the same vertical axis as the skull, and the skull crucibles and consumable electrode feed mechanisms are installed in parallel and symmetrically with respect to the vertical axis of the centrifugal table.

The invention meets the criteria of patentability; has novelty, which follows from a comparison with the prototype; inventive step, as it clearly does not follow from the existing level of technology; industrially applicable.

Figure 1 presents a structural diagram of the proposed vacuum smelting and casting plant, a longitudinal section; figure 2 - feed mechanisms of the consumable electrode and the stand for welding of the consumable electrode, view along arrow A in figure 1; figure 3 is a section of a stand for welding a consumable electrode BB in figure 2.

The vacuum arc melting and casting installation consists of a vacuum working chamber 1 with a water cooling system, two skull plates 2, two feed mechanisms for a consumable electrode 3, a separate stand for welding a consumable electrode 4, and three centrifugal tables: right 5, left 6 and central 7.

The working chamber 1 is a horizontally located welded structure equipped with end caps 8. The end caps 8 are placed on carts 9, which are mounted on rails 10.

Three centrifugal tables are mounted on the cast iron bed 11, which is common with the working chamber 1, three centrifugal tables: right 5, left 6 and central 7, driven by individual motors. DC motors are selected taking into account the smooth adjustment of the rotation speed from 200 to 400 rpm.

On the tables of centrifugal machines 5, 6 and 7, containers of foundry molds are installed, respectively 12, 13 (up to 300 kg for molten metal) and 14 (up to 600 kg for molten metal), or other casting equipment. Containers of casting molds 12, 13 and 14 are pressed against the tables of centrifugal machines 5, 6 and 7 by centrifugal locks.

Over the containers of casting molds 12, 13 and 14, filling devices 15, which are welded structures of sheet material and pipes, are suspended using special fastening.

Two skull 3 crucibles in rotary water-cooled cases, which ensures crucibles are rotated 105 ° on both sides of the vertical plane using electric drives, are placed in the melting and filling chamber 1 parallel to each other. In this case, the central centrifugal table 7 is located between two skull plates 2, which makes it possible to simultaneously pour metal from two skull plates 2 into the container of molds 14. Two side centrifugal tables 5 and 6, on which mold containers 12 and 13 are installed, located on the outer sides of the skull plates 2.

Above each skull crucible 2, on the same vertical axis, there are disposed electrode feeding mechanisms 3. Two electrode feeding mechanisms 3 are mounted on separate structures installed independently of the working chamber 1 on the main frame 11.

An electrode feed station provides electrode movement up and down. Current leads to the electrodes 16 are made of flexible copper braids.

The welding stand of the consumable electrode 4 is located separately from the working chamber 1 on the bed 11 between the feed mechanisms of the consumable electrode 3.

The water cooling system consists of pressure head 17 and drain 18 collectors.

Vacuum arc melting and casting plant operates as follows.

First, they prepare the vacuum arc melting and casting plant for melting. The inner surface of the furnace (walls of the vacuum working chamber 1, water-cooled crucible rings 2, electrode holder rods on two electrode feeding mechanisms 3) is thoroughly cleaned with a vacuum cleaner. In order to degrease and remove moisture, thoroughly wipe the inside of the furnace with hydrolysis alcohol.

Install and fix on the tables of centrifugal machines 5, 6 and 7 pre-assembled containers of foundry molds 12, 13 and 14, or other foundry equipment. At a distance of 30-50 mm from the upper edge of the central riser, an intermediate sprue bowl 15 is suspended using special fastening.

If necessary, a new electrode is welded to the cinder of the electrode 4 used on the stand. Welding of the consumable electrode is carried out alternately for each of the two feed mechanisms of the consumable electrode 3. To do this, the whole structure of one of the two feed mechanisms of the electrode 3 is rotated 90 °, after which welding of a consumable electrode. After welding the consumable electrode, the feed mechanism of the electrode 3 returns to its working position.

The working chamber 1 is closed by sliding end caps 8 and vacuum. Then water is supplied to all water-cooled parts of the installation.

Next, the first melting and pouring of metal into the mold container 14 is carried out, located on the central centrifugal table 7, which is located between the two crucibles 2. To do this, the electrodes 3 feed the electrodes to a short circuit with the bottom of the skull plates 2, turn on the power source and remove the electrodes from the bottom by 20-30 mm to the appearance of electric arcs.

When centrifugal casting of molds two minutes before the end of melting, the centrifugal machine of the central table 7 is turned on and the number of revolutions is adjusted to the set one. After deposition of the required amount of metal in two skull crucibles 2, the electric arcs are turned off, the electrodes are fed up by feeding mechanisms 3, and metal is simultaneously drained into the mold container 14 through the casting tray 15 located above this container from the skull crucibles 2.

When the pouring of the mold container 14 ends, the crucibles 2 and the electrodes are returned to the working position and the second melt is carried out - they turn on the power supply, light the electric arcs and melt the metal in the skull rods 2. Two minutes before the end of the melting, the centrifugal machines of the side tables 5 and 6 are turned on After deposition in the crucibles 2 of the required amount of metal, the arcs are turned off, the electrodes are removed and the metal is poured into containers of casting molds 12 and 13 through casting trays 15 located above these containers.

Next, the cooling containers of molds 12, 13 and 14 for 1.5-2 hours in vacuum.

Then, the water cooling system is turned off, depressurization of the working chamber of installation 1 and opening of the end caps 8, after which the containers of molds 12, 13 and 14 are removed.

The proposed vacuum arc melting and casting installation allows batch casting of three containers of casting molds in one working cycle of the melting and casting installation without depressurization of the furnace in the interval between the two melts.

The use of such a smelting scheme leads to a significant increase in the furnace productivity and a reduction in the cost of producing castings due to the overlap of the stages of the working cycle, especially the cooling of the castings (the longest stage of the working process of a vacuum arc smelting and casting plant) and the exclusion of repeated evacuation of the furnace.

In this vacuum arc melting and casting installation, metal is simultaneously poured simultaneously from two skull plates into the central container of molds, which makes it possible to produce massive castings (up to 600 kg for liquid metal).

Thus, this vacuum arc melting and casting installation provides a wide range of engineering castings (from 150 kg to 600 kg for molten metal) of high quality, easy to maintain and economical in operation.

Claims (1)

Vacuum arc melting and casting installation containing a vacuum working chamber with a water cooling system, a skull crucible placed in the working chamber, a consumable electrode feed mechanism mounted above the skull crucible on the same vertical axis, two side centrifugal tables and a consumable electrode welding stand, different the fact that the installation is additionally equipped with a central centrifugal table located between two lateral centrifugal tables, a second skull plate and a feed mechanism consumable electrode mounted on a second one skull crucible with it vertical axis, the skull crucible and the consumable electrode feed mechanisms are arranged in parallel and symmetrically about a vertical central axis of the centrifugal section.

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