RU2360014C2 - Vacuum arc-refining skull furnace - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: provided invention relates to special metallurgy field and can be used for melting of ingots of refractory, high- reacting metals and alloys, predominately titanic, used in aerospace engineering. At top working side of underpan it is implemented central notch by shape and dimensions of sternpost of working stub of ingot-electrode.

EFFECT: invention provides receiving of monolithic ingot - electrode with reverse stub in skull furnace, exclude operations of welding of consumed stub to ingot-electrode, to remove manufacturing of fusers and all complex of facilities and equipment by its processing, to extend accuracy of unit, alignment and fixation in pallet of fill in ingot-electrode in mold of major diametre.

1 ex, 4 dwg

Description

The present invention relates to the field of special electrometallurgy and can be used for the smelting of ingots of refractory highly reactive metals and alloys, mainly titanium, used in aerospace engineering.

The choice of a technological scheme for the production of these alloys is determined by their purpose and quality requirements for semi-finished products. For the bulk of the ingots, the main requirement is the purity of the metal from internal inclusions and the uniformity of the chemical composition, as well as the efficiency of the processes. In addition to ensuring high quality and cost-effectiveness, the technological scheme for the production of ingots must meet the requirements of safety and environmental protection.

To obtain high-quality ingots used in aviation, engine building, astronautics and other high-tech fields, double and triple remelting ingots are used. The optimum technology for the first remelting is skull molding. It ensures the involvement of the amount of waste necessary for the calculation, the complete averaging of the alloy composition, and the absence of rejects for inclusions of heavy refractory particles remaining at the bottom of the crucible. Further, the ingots are obtained by vacuum-arc remelting. This allows you to get high-quality metal with a good structure. However, vacuum-arc remelting contains a number of high-cost technological operations associated with transporting the ingot, loading it into the furnace and welding the cinder, these operations are accompanied by contamination of the ingots, unproductive work and downtime of the furnaces.

Known vacuum arc skull furnace DTVG4PF containing a working chamber, an electrode holder, a copper cooled crucible and a mold with a flat tray. The formation of the ingot electrode in the used skull furnace can be performed in one or several consecutive heats, while the previous ingot is obtained in a mold of a smaller diameter. During subsequent melting, the ingot is mounted on a flat tray in a mold of a larger diameter mold, and the cavity formed around it is filled with a melt. [1] is a prototype.

A disadvantage of the known skull furnace is the used flat mold tray, as a result of which the bottom surface of the cast ingot electrode is flat. For this reason, when installing the cast ingot on a flat pallet, the necessary accuracy of alignment and fixation of the ingot electrode during subsequent melting in a larger diameter crystallizer is not provided. The final ingot electrode is not adapted to be mounted on the electrode holder of a vacuum arc furnace. To do this, the consumable cinder is arc welded to the bottom end of the ingot electrode, accompanied by metal spatter, the formation of sagging, splits, kings and chlorides that pollute the furnaces, their electrode holders with cinders fixed on them, and therefore, this creates the preconditions for obtaining an alloy with possible presence defects. After welding, a manual dry cleaning of the furnace is performed, which is harmful to the health of the performer. The bottom part of the ingot electrode welded to the consumable cinder is not melted, left in the form of a “pancake” 40–80 mm high, the melting of which requires an additional technological operation. An additional operation is carried out after unloading the obtained ingot with a crystallizer from the furnace, subsequent loading of a special shallow mold “bowl”, and the remaining “pancake” is melted, receiving a melter, which, after a rather complicated treatment in the form of waste, is involved in the technological process. As a result, in the melting work cycle, the main equipment (vacuum arc furnace) is loaded up to 35% of the time with auxiliary operations, and 2-3% of the suitable metal is spent on used consumable cinders and melted floats.

The objective of the invention is to obtain a monolithic ingot electrode with a cinder in the skull furnace without the use of consumable cinders and the operation of welding them to the ingot electrode.

The technical result achieved by the invention is:

- the accuracy of installation, alignment and fixation in the pan poured ingot electrode in the mold of a larger diameter,

- elimination from vacuum arc furnaces of the auxiliary operation of melting “pancakes” - ingot electrodes and crystallizers - “bowls”,

- elimination of the production of floaters and the whole range of facilities and equipment for their processing,

- increase the productivity of the furnace,

- improving the culture and safety of the production of ingots, the quality of titanium products and reducing its cost,

- improvement of the environment and working conditions,

- elimination of the use of double, triple weldable suture ingots-electrodes.

The technical result is achieved by the fact that, in a vacuum arc skull furnace for receiving ingots-electrodes of titanium alloys containing a working chamber, an electrode holder, a copper cooled crucible and a crystallizer with a flat pallet, a central recess is made on the upper working side of the pallet in shape and size of the tail part of the reverse cinder-electrode cinder.

The invention is illustrated graphic material:

Figure 1 shows the claimed vacuum arc skull furnace. Figure 2 shows the fixation of the filled ingot electrode in a larger diameter crystallizer. Figure 3 - the obtained ingot electrode with a cinder on the bottom. Figure 4 is a photograph of a pallet with a recess.

Obtaining ingots-electrodes in accordance with the claimed invention is as follows.

After the consumable electrode 1 and the charge 2 are melted in the crucible 3, the first melt through the drain funnel 4 is poured into the mold 5, forming a monolithic ingot electrode 6 with a cinder 7 on the tray 8 with a recess 9. The resulting ingot electrode is installed in the mold 10 during subsequent melting a larger diameter and fill the resulting cavity with melt 11. The cooled ingot-electrode is discharged from the furnace, and at the end of its cinder, a shank is pierced, which is necessary to fix the ingot-electrode on the electrode holder of the second-remelting vacuum arc furnace VDP.

The prepared ingot electrode 12 with a cinder is fixed on the electrode holder of a vacuum arc furnace and is remelted.

Example.

On the DTVG4PF furnace reconstructed according to the invention, for the first time in titanium metallurgy, ingots-electrodes with a diameter of 672 mm weighing up to 5 tons with revolving cinders on their bottom were obtained. As a result of their use in remelting in vacuum arc furnaces DTV8,7G10, ingots of critical alloys (for the manufacture of aircraft chassis) 10-2-3 with record performance were smelted.

This invention allowed to obtain:

- Seamless high-precision ingots-electrodes with revolving cinders on their bottom part during the main technological operation (smelting of an ingot in a skull furnace);

- to ensure accurate alignment of the ingot electrode during remelting in a vacuum arc furnace, which increases the explosion safety of the melting;

- allows you to exclude from the process operations that create the prerequisites for metal contamination by refractory inclusions;

- excludes technological operations with harmful working conditions;

- improves productivity in the smelting of ingots of double and triple remelting.

Information sources

1. Application for patent No. 2005131893/02 of 04.20.2007.

Claims (1)

A vacuum arc skull furnace for producing ingots-electrodes of titanium alloys containing a working chamber, an electrode holder, a copper cooled crucible and a crystallizer with a flat pallet, characterized in that a central recess is made on the upper working side of the flat pallet of the mold in the shape and dimensions of the tail of the ingot electrode.

Images