RU2358216C2 - Melting crucible, water-cooled - Google Patents

Abstract

FIELD: heating.

SUBSTANCE: invention relates to metallurgy, immediately dealing with design of melting equipment for vacuum-arc, plasma-arc and electron-beam furnaces. The proposed water-cooled melting crucible is designed to be composed of bimetallic copper-and-steel panels with internal hermetically-sealed water-cooled channels. The crucible additionally contains a framework providing for each panel position lock, fixtured on one side, and free relocation of the panels contacting surfaces relative to each other. The panels design potentially enables electrical contact due to resilient connections. The water-cooled channels are arranged on the bimetallic panel outside (the steel sheet side) and are hermetically covered with steel plates, welded on.

EFFECT: reduction of the mechanical stress within the crucible structure resulting from the crucible component parts contacting under thermal expansion conditions.

2 cl, 3 dwg

Description

The invention relates to smelting equipment, and in particular, to structural elements of vacuum arc furnaces, plasma-arc and electron-beam furnaces, in the construction of which a water-cooled melting tool is used.

The smelting of reactive refractory materials without contamination on an industrial scale is possible only in cold crucibles, i.e. in containers, the working temperature of which is lower than the temperature of the remelted material. In one way or another, heat is generated in the cage, it is possible to create a stable bath of melt that is directly in contact with the cold crucible or separated from it by a layer of unmelted material (skull). The skull protects the melt from the influence of the crucible. Melting with a skull guarantees absolute purity of the melt.

In the process, the melting tool experiences large thermal loads. Heat flows through its walls can reach from hundreds to thousands of kilowatts per square meter, and in emergency situations exceed this value. Large temperature gradients result in thermal stresses. In addition, the tool experiences large mechanical loads from the weight of its own design and the weight of the melt, cyclic loads. Burn-through of the tool, loss of tightness or other even local destruction of the tool structure are unacceptable. For example, the destruction of the crucible during the smelting of titanium entails not only a steam explosion, but also an explosion of an explosive mixture, since titanium interacts with water with its dissociation and the release of free hydrogen.

Known cold crucibles, which are made in the form of segments from profiled non-uniform copper tubes or massive welded milled copper sections (AS USSR No. 273373, 1970).

Crucibles are structurally complex, laborious to manufacture and are used in furnaces with a relatively small melt volume.

Known melting water-cooled crucible containing a metal body with sealed internal cooling channels, the body is made of bimetallic plates obtained by explosion welding of a copper layer with a layer of stainless steel. In the plate obtained in this way, by means of the directed movement of a special cutter, cooling channels are formed in the copper layer, with the help of which the thermal processes in the crucible are adjusted. The plates are interconnected by elastic elements. Water-cooled channels are made in one plane (RF patent No. 2166714) - prototype.

The disadvantage of this design is that the connection of the crucible elements is carried out by rigid hairpin mounts, which can elastically compensate for temperature expansion only in the direction of one degree of freedom - along the axis of the stud. Therefore, stresses appear in the walls and bottom of the crucible caused by various thermal expansion, having different direction vectors in the outer and inner layers of these elements due to the large temperature gradient during the melting process. The completed channels have a significant depth, which is regulated by the design features of this part of the device. With this design of the system of water-cooled channels and the power fastening of the crucible elements during titanium melting, according to the calculated and experimental data, the thickness of the copper plate cannot be less than 190-200 mm, and the steel plate less than 10 mm. The interconnection of the steel and copper layers of the plate is done by explosion welding. In this case, the welding process imposes restrictions on the thickness of the connected layers. The smaller the thickness, the easier it is to weld and, as a result, the cost of a bimetal plate is less. The manufacture of a bimetallic plate, consisting of a copper layer 200 mm thick and a steel layer 10 mm thick, is costly and technologically challenging.

The problem to which this invention is directed, is to increase the life of the crucible, reduce the cost and metal consumption of the structure, simplify manufacturing technology, increase maintainability.

The technical result achieved by the implementation of the invention is the minimization of mechanical stresses in the design of the crucible arising from the contact of the parts of the crucible during their thermal expansion.

The specified technical result is achieved in that the water-cooled melting crucible, consisting of copper-steel bimetallic plates, which contain internal hermetic water-cooled channels, additionally contains a frame in which the position of each plate is fixed by its one-sided jamming, while providing a free bias of the contacting surfaces of the plates relative to each other other, the electrical contact between the plates is ensured by elastic joints, and the water-cooled channels, which are sealed from above Ski closed welded steel plates are formed on the outer surface of the bimetallic plates from steel sheet.

On the outer surface of the bimetallic plates from the side of the steel sheet, compensation grooves are additionally made.

The invention is illustrated by drawings, where in Fig.1 shows a General view of the crucible, Fig.2 is a cross section of a water-cooled plate, Fig.3 is a diagram of the thermal expansion of the walls of the crucible.

The water-cooled melting crucible contains a frame 1, in which a bottom 2, side walls 3, a front wall 4 and a rear wall 5 are installed and fixed. The bottom and walls are made of solid-rolled bimetallic plates consisting of a copper plate 6 and a steel sheet 7. The plates are fixed in the frame from one end by means of a fixing unit 8. On the surface of each plate from the side of the steel sheet 7, water-cooled grooves 9 are made, which are covered from above by steel plates 10. The plates are attached by a continuous vacuum-tight weld 11. Each plate has an inlet 12 and an outlet 13 for supplying water. The electrical contact between the plates is provided by elastic conductive joints 14. To reduce to an acceptable level of mechanical stresses at the interface of the steel and copper joints, caused by the unevenness of their thermal expansions, compensation grooves 15 are made.

Melting water-cooled crucible works as follows. Before melting, a rod 16 (a skull-electrode holder) and a embedded wall 17 are installed in the rear wall 5. The rod 16 is made of an alloy similar to a melting alloy, and a charge is laid on the bottom of the crucible. Above the crucible, on the electrode holder of the furnace, a rod 16 is fixed with the skull of the previous melting welded to it. After fusion of the skull electrode, the metal is drained by tilting the crucible through the drain sock 18 into the mold (not shown in the drawing). The mass of the merged metal is 7 tons. After cooling, the furnace is depressurized, the resulting skull-electrode with a rod 16 welded to it is removed from the crucible. The mold with the fused metal is unloaded. Then the process is repeated.

Due to the rational design of the crucible, the thermal change in the dimensions of the plates does not cause mechanical stresses at their contact points. Scheme of thermal expansion of the walls in the crucible is shown in Fig.3. In addition, the compensation grooves 15 prevent the occurrence of significant material stresses at the copper-steel interface.

The proposed design has reduced the thickness of the copper plate from 200 mm to 55 mm, and the thickness of the steel sheet from 10 mm to 5 mm. Accordingly, the crucible mass was reduced by more than three times, the cost of making the crucible decreased. Crucible melt capacity increased by more than 30%.

Claims (2)

1. Melting water-cooled crucible, consisting of copper-steel bimetallic plates with internal hermetic water-cooled channels, characterized in that it further comprises a frame for fixing the position of each plate with its one-sided jamming and ensuring free displacement of the contacting surfaces of the plates relative to each other, while the plate made with the possibility of ensuring electrical contact due to elastic joints, and water-cooled channels are made on the outer surface of each plate with Torons steel sheet and top sealed by welded steel plates. 2. Melting water-cooled crucible according to claim 1, characterized in that on the outer surface of each plate from the side of the steel sheet, compensation grooves are additionally made.

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