RU2705832C1 - Electric holder of arc electric furnace - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: invention relates to electrometallurgy, namely to electrode holders for arc melting and ladle furnaces for metal melting and heating. Contact jaw is made bimetallic, one layer of which is steel, and the other is copper, wherein between this part of the jaw and the graphitized furnace electrode there is a graphite insert, one surface of which is tightly adjacent to the copper current-conducting surface of the jaw, and the other surface has a curvature repeating the curvature of the surface of the graphitized electrode.

EFFECT: invention reduces weight of electrode holder by replacing part of copper contact jaw with steel, considerably simplifies assembly of assembly due to complete failure of deep drilling of copper billet, increases its operational durability due to increased area of contact of electrode with current-conducting part of structure through graphite insert and reliability of whole assembly, as well as improved repairability of electrode holder.

1 cl, 5 dwg

Description

The invention relates to electrometallurgy, and in particular to arc melting and ladle furnaces for melting and heating metal.

The issue of combining good conductivity while ensuring the rigidity of a current-carrying unit in electrical technology has always been relevant. As a rule, its solution was associated with an increase in the volume of conductive material (mainly copper), which entailed a partial increase in mechanical strength. This way, however, had its own, rather serious, negative consequences, which led to an increase in the metal consumption of the entire unit, and, as a consequence, to its rise in price. In addition, situations arise when the machining of a current-carrying assembly or a component of the assembly itself is extremely time-consuming, but necessary, and in this case the indivisible connection of two dissimilar metals into a whole makes it possible to simplify further machining, and in some cases even exclude it.

The electrode holder consists of a head with a clamp and a copper water-cooled contact jaw for supplying current to a graphite electrode, a conductive sleeve for transmitting current from flexible cables to the contact jaw and a spring-hydraulic mechanism for clamping or expanding the electrode, while the contact jaw is made of bimetallic copper and steel layers, moreover, between the copper part of the plate and the graphite electrode of the furnace there is a graphite insert adjacent one side to the copper surface of the cheek, and on the other its Rhone adapted to the surface curvature, the curvature of repeating graphite electrode surface.

The invention allows to create a rigid design of the electrode holder, to reduce the active and inductive resistance of the current-supply sleeve and thereby reduce electrical losses during furnace operation due to the snug fit (including due to the electrode pressing force) of the flat part of the graphite liner to the plane of the copper part of the water-cooled contact cheek.

Known electrode holder of an electric arc furnace containing a current-carrying sleeve, an electrode clamping mechanism and a head with contact cheeks, in which the current-carrying layer of the sleeve is made in the form of a monolithic hollow billet of aluminum alloy reinforced with a bundle of steel pipes (see patent RU 2145469 C1).

The electrode holder of the arc furnace is also known, the head of which is designed to clamp a graphite electrode with a diameter of 350 mm and supply electric current to it. The electrode clamp is carried out with a clamp (pos. 8 of Fig. 1). The head of the electrode holder is a welded body structure (pos. 5 of Fig. 2) made of non-magnetic stainless steel, on which two copper contact cheeks are fixed (pos. 4 of Fig. 1). Current supply is carried out through a copper contact plate (item 1 of Fig. 2), welded to the top of the contact cheeks. Cooling water is supplied through a pipe (pos. 2 of Fig. 2), welded into the hole of the contact cheek, then the water passes through the channels of the contact cheeks made by deep drilling. The connection of the channels of the contact jaws is provided by a pipe (pos. 3 of Fig. 2).

Also known is the prototype electrode holder of the electric arc furnace (5NF.108.198. SB. Electrode holder, Sat drawing. SKB "Sibelektroterm"), containing a current-carrying sleeve, an electrode clamping mechanism and a head with a contact cheek, in which a copper plate is used to cool the contact surface of the cheek 120 mm thick., in the body of which a cooling channel is organized using deep drilling. The electrode clamp is carried out with a clamp (pos. 2 of Fig. 3). The design of the contact jaw (pos. 1 of Fig. 3) provides for a combined current supply and supply of cooling water.

A disadvantage of the known designs is the heating of the contact jaw under the influence of passing currents, shock short circuits and resonance phenomena due to the fact that the electrodes supplied by our industry come with plus and minus deviations in diameter (according to GOST 4426-80), which entails situations in which the contact surface of the electrode-cheek is insufficient, because actually reduced to individual points (Fig. 4). If the diameter of the electrode deviates in one direction or another, which almost always takes place, the contact between the cheek and the electrode turns out to be linear at best (either along lines 2 and 3, or along lines 1 and 4 of Fig. 4). From here follows the main drawback of the existing designs of the electrical contact node of the electrode holder - high contact resistance. As a result, vibration of the structure and the emergence of micro-arcs.

The technical result of the invention is to reduce the mass of the electrode holder by replacing part of the copper contact jaw with steel, significantly simplifying the manufacture of the assembly due to the complete rejection of deep drilling of the copper billet, increasing its operational stability by increasing the contact area of the electrode with the current-carrying part of the structure through a graphite insert and, as a consequence of the reliability of the entire assembly, and the improvement of maintainability of the electrode holder, which now consists in replacing only graphite liner, not the entire site.

To eliminate the above-mentioned drawbacks of the known constructions of the electrode holder, to provide the necessary rigidity and allowable heating with minimum dimensions and reduced weight of the assembly, an electrode holder design is proposed, consisting of a head with a clamp and a contact cheek for transmitting current from flexible cables of a short network to the contact cheek and an electrode clamping / expanding mechanism .

A distinctive feature of the proposed design of the electrode holder, which provides its advantages over the known structures, is that to improve the conductivity of the structure by reducing its contact resistance, and hence heating, the contact cheek is made bimetallic, one layer of which is steel, provides structural rigidity, and the other - copper, good electrical conductivity, and a graphite insert is installed between this part of the cheek and the graphitized electrode of the furnace, one surface five of which adheres to the surface of the copper conductive cheeks, and the other surface has a curvature, the curvature of repeating graphite electrode surface. In addition, the mass of the entire assembly is significantly reduced by replacing a part of the copper structure with a steel one.

Thanks to the above construction, the following advantages of the inventive electrode holder are achieved with a decrease in its weight compared to known analogues:

- the contact surface of the electrode - the electrode holder cheek is increased due to the fact that the graphite electrode is “rubbed” well and quickly to the graphite insert, and the graphite insert itself, with its other contact surface (plane), fits well with the same force during clamping of the electrode, but copper plane of the contact cheek;

- the vibration of the electrode holder during operation is reduced due to improved contact between the electrode and the jaw of the electrode holder;

- improved cooling of the contact surface due to the fact that increased volume of water, constantly located in the body of the contact cheek;

- increases the operational stability and reliability of the electrode holder;

- the manufacturing process of the electrode holder is greatly simplified due to the complete rejection of deep drilling of the copper billet with all the ensuing difficulties (hardening of copper on the tool with the drill leading away from the vertical);

- maintainability of the electrode holder is improved, which consists only in replacing the graphite liner, and not the entire assembly. This eliminates the need to replace the entire contact cheek.

Conducted in the process of filing an application for the proposed invention, a search for scientific and technical sources of information and identifying sources containing information about analogues of the claimed invention did not allow to find an analogue characterized by features identical to the essential features of this invention. The definition from the list of identified analogues of the prototype as the closest in the totality of features made it possible to identify a number of distinctive features relative to the technical result of the claimed design of the electrode holder set forth in the claims. Therefore, the claimed invention meets the condition of "novelty."

An additional search for known solutions to verify compliance of the claimed invention with the condition "inventive step" did not reveal signs that match the distinctive features of the prototype of the claimed electrode holder or resulting explicitly from the prior art. Therefore, the claimed invention meets the condition of "inventive step".

In the proposed design, the contact electrode - the electrode holder jaw is divided into two contacts (Fig. 5):

1. Cheek - graphite liner;

2. Graphite insert - electrode.

The electric current passing through the pipes welded into the hole (pos. 1 of Fig. 5) passes to the copper part of the bimetallic plate and then to the planar contact of the cheek - a graphite insert (pos. 2 of Fig. 5). The graphite insert is firmly and firmly held on the copper part of the bimetallic plate using dovetail guides. Having passed through a graphite insert (pos. 3 of Fig. 5), the current approaches the electrode – graphite insert contact (pos. 4 of Fig. 5), which is also planar (according to the diameter of the electrode, along an arc), because during the bypass of the electrode, the insert and the electrode will inevitably “rub” against each other.

For the manufacture of the head of the electrode holder, a bimetallic plate with a thickness of 20 mm is required. The contact (working) side of the plate is copper, and the inner steel. The plate can easily be made using electroslag remelting. Grooves are milled on the copper side to the steel base in order to weld the dovetail guides.

Then the guides themselves are welded. On the inner - steel side, fins are welded and individual parts of the steel sheet are milled to copper in order to organize good cooling of the latter. From above and from the sides, everything is closed with a steel sheet and boiled around the perimeter to obtain a closed cooling jacket.

This design has high maintainability, which consists only in replacing a graphite insert (it, in turn, can be easily made from an electrode “battle”, which is available in large quantities near the arc furnace). Obtaining reliable contact between the liner and the electrode is achieved by bypassing the electrode.

Claims (1)

An electrode holder for an electric arc furnace containing a head with a clamp and a water-cooled contact cheek for supplying current to a graphite electrode, a conductive sleeve for transmitting current from flexible cables to the contact cheek, and a spring-hydraulic electrode clamping or expanding mechanism, characterized in that the water-cooled contact cheek is made of bimetallic copper and a steel layer, and between the copper part of the plate and the graphitized electrode of the furnace there is a graphite insert adjacent one side to the bottom surface of the cheek, and on the other hand, made with the curvature of the surface, repeating the curvature of the surface of the graphitized electrode.

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