RU2060102C1 - Production line process of vacuum treatment of metal under continuous casting and device for its realization - Google Patents

Abstract

FIELD: metallurgy. SUBSTANCE: production line process of vacuum treatment of metal under continuous casting includes supply of metal out of casting ladle vacuum chamber, formation of needed residual pressure in it, treatment of metal in vacuum chamber, supply of metal into intermediate ladle through discharge branch pipe under level and further on into moulds and drawing of ingots from moulds. In process of casting rate of flow of metal from discharge branch pipe is reduced by 10-60% of working value. Device for its realization includes vacuum chamber with discharge branch pipe installed into its bottom and going into intermediate ladle. Discharge branch pipe is fitted with electromagnetic brake. EFFECT: enhanced vacuum treatment efficiency. 2 cl, 1 dwg, 1 tbl

Description

 The invention relates to metallurgy, and more particularly to continuous casting of metals.

There is a method of continuous metal evacuation of a metal during continuous casting and a device for its implementation, comprising supplying liquid metal from a casting ladle to a vacuum chamber, creating a vacuum in it to the residual pressure required by the technology, supplying metal from a vacuum chamber through a separate pipe directly to the mold under metal level. Under these conditions, the vacuum chamber serves as a hermetically sealed intermediate ladle connected to the vacuum wire. The metal level in the vacuum chamber is kept constant [2]
The disadvantages of this method are the lack of performance and stability of the process of continuous casting of metals. This is due to the fact that in case of a violation of the tightness of the vacuum chamber, the mold overflows. Under these conditions, the continuous casting process is terminated. In addition, with the known method, it is impossible to adjust the flow of metal into the molds depending on the changing technological parameters of the casting process.

The closest in technical essence to the invention are a method of continuous metal evacuation during continuous casting and a device for its implementation, including feeding liquid metal from a casting ladle into a vacuum chamber, creating a vacuum in it to the residual pressure required by the technology, feeding metal into an intermediate ladle through separate pipe and further into the molds. The consumption of metal from the tundish is regulated by means of stoppers. After raising the metal level in the intermediate ladle above the lower ends of the nozzles and sealing the vacuum chamber with liquid metal, they begin to reduce the residual pressure in the chamber. The metal level in the vacuum chamber is kept constant [2]
The disadvantages of the known method and device are insufficient productivity and stability of the process of continuous metal evacuation during continuous casting. This is due to the fact that in the process of in-line evacuation, drops of liquid metal from its stream adhere and weld onto the lined side walls of the working cavity of the vacuum chamber, forming inflows. In the process of casting the ladle over time, the volume of the internal working cavity of the vacuum chamber decreases, which leads to a decrease in the efficiency and productivity of the process of continuous metal evacuation.

 The technical effect when using the invention is to increase the productivity and efficiency of the process of continuous metal evacuation during continuous casting.

 The specified technical effect is achieved by the fact that the metal is fed from the casting ladle into a vacuum chamber equipped with a vacuum wire, the residual pressure required by the technology is created in it, the metal is processed in a vacuum chamber, the metal is fed into the intermediate ladle through a drain pipe below the level and then in the molds, and also draw ingots from the molds.

 In the process of casting, the flow rate of the metal from the drain pipe is periodically reduced by 10-60% of the operating value.

 In addition, the device for implementing the method of continuous metal evacuation during continuous casting includes a vacuum chamber with a drain pipe installed in its bottom and included in the intermediate ladle. The drain pipe is equipped with an electromagnetic brake.

 Increasing the productivity and efficiency of the process of continuous metal evacuation during continuous casting will occur as a result of keeping the volume of the working chamber of the vacuum chamber constant due to the elimination of the flow of frozen metal from its side walls by raising the level of the metal layer located at the bottom of the vacuum chamber.

 The range of decrease in the rate of expiration of the metal stream passing through the drain pipe by 10-60% of the operating value is explained by the need to raise the level of the metal layer located at the bottom of the vacuum chamber to the required height. At lower values, the level of the metal layer in the vacuum chamber will not rise to the required height. At large values, a reduced metal consumption will cause a decrease in the speed of drawing the ingots from the molds, which will cause a violation of the stability of the process of forming continuously cast ingots and their marriage.

 The specified range is set in direct proportion to the weight flow of metal from the casting ladle.

 The analysis of scientific, technical and patent literature shows the lack of coincidence of the distinguishing features of the proposed method with the signs of known technical solutions. Based on this, it is concluded that the claimed technical solution meets the criterion of "Inventive step".

 The following is an embodiment of the invention that does not exclude other variations within the scope of the claims.

 The drawing shows a diagram of a device for implementing the method of continuous metal evacuation during continuous casting.

 A device for implementing the method of continuous metal evacuation during continuous casting consists of a casting ladle 1, a vacuum chamber 2, a drain pipe 3, an intermediate ladle 4, pouring glasses 5, molds 6, a vacuum wire 7, an electromagnetic brake 8. Position 9 denotes liquid metal , 10 level metal; 11 continuously cast ingot.

 The method of continuous metal evacuation during continuous casting is carried out by a device that operates as follows.

 PRI me R. In the process of continuous casting, liquid non-deoxidized steel 9 of grade st3 is supplied from a casting ladle 1 with a capacity of 350 tons to a vacuum chamber 2 and a vacuum is created in it to the residual pressure required by the technology in the range of 0.3-0.5 kPa, depending on the deoxidation of the steel. The vacuum is created by means of a vacuum wire 7 located in the upper part of the working cavity of the vacuum chamber 2 and connected to a vacuum pump. The metal 9 from the vacuum chamber 2 is fed into the intermediate ladle 4 with a capacity of 50 tons through the refractory pipe 3 under the metal level 10. Next, the metal from the intermediate ladle 4 is fed through elongated refractory glasses 5 to the molds 6 under the metal level. Two continuously cast ingots 11 are drawn from the crystallizers 6. The flow rates of the metal 9 from the casting and intermediate ladles are regulated by means of stoppers.

 The internal working cavity of the vacuum chamber has a diameter of 1.6 m.

 In the process of vacuum processing of metal on the bottom of the vacuum chamber, the working level of the metal is maintained at a height of 200 mm from the bottom of the vacuum chamber.

 An electromagnetic brake 8 is installed on the drain pipe 3, to which electricity is supplied. The diameter of the channel pipe 3 is 150 mm

 During the vacuum treatment of metal on the side refractory walls of the working cavity of the vacuum chamber, flows of crystallized metal are formed, which leads to a decrease in the volume of the vacuum chamber and, as a result, to a decrease in the efficiency of the vacuum process.

 In the process of continuous casting, the flow rate of the metal stream passing through the drain pipe 3 is periodically reduced by applying voltage to the electromagnetic brake 8 by 10-60% of the operating value.

 When the brake 8 is operating, a magnetic field is created that drives the molten steel located in the drain pipe 3. The electromagnetic brake 8 uses the fact of the movement of the metal jet in the drain pipe 3 with a stationary magnetic field. As a result of this, voltage arises in the metal stream and closed electric currents are created. These currents, interacting with a stationary electromagnetic field, inhibit the stream of metal in the drain pipe.

 The magnitude of the decrease in the rate of expiration of the metal stream from the drain pipe is set in direct proportion to the weight flow of metal from the casting ladle by adjusting the voltage supplied to the electromagnetic brake windings.

 When reducing the flow rate of the jet of metal 9, its flow rate decreases from the vacuum chamber 2. Under these conditions, the level of the metal layer 9 located at the bottom in the vacuum chamber increases by 100-800 mm, depending on the weight flow rate of the metal from the casting ladle 1 and the duration of the electromagnetic brake 8.

 The inclusion of the electromagnetic brake 8 is carried out with a frequency of 5-20 minutes casting time of the casting ladle 1.

 The table shows examples of the method of continuous metal evacuation during continuous casting with various technological parameters.

 After raising the level of the metal in the vacuum chamber to the required height, it is maintained at this level for 2-5 minutes, after which it is lowered to the operating value.

 In the first example, due to a slight decrease in the speed of the metal stream in the drain pipe and, consequently, the consumption of metal, the level in the vacuum chamber rises by 60 mm, which is insufficient to remove the influx of metal from the side refractory walls of the vacuum chamber.

 In the fifth example, due to a significant decrease in the speed of the metal stream in the drain pipe and, consequently, the consumption of metal, the level in the vacuum chamber rises by 900 mm. However, at the same time, the speed of drawing the ingots must be reduced to 0.4 m / min, which leads to the rejection of ingots by surface quality and macrostructure.

 In the sixth example, the prototype, due to the absence of a decrease in the velocity of the metal stream from the nozzle, there will be no increase in the level of the metal in the vacuum chamber, which will lead to a gradual decrease in the volume of the working cavity of the vacuum chamber and, as a result, to a decrease in the efficiency and productivity of the process of in-line evacuation .

 In examples 2-4, due to a decrease in the speed of the metal stream from the nozzle to the optimum limits, the metal level in the vacuum chamber increases within the range of 100-800 mm, sufficient to melt and remove crystallized metal sagging from the side walls of the vacuum chamber.

 In the process of changing the level of the metal in the vacuum chamber, the melting and removal of metal flows from the side walls of the vacuum chamber occurs. As a result, the volume of the internal working cavity of the vacuum chamber is restored to its previous size. As a result of this, high efficiency and productivity of the process of continuous metal evacuation in the vacuum chamber are maintained.

 After raising the metal to the required level, it is reduced to the working value.

 The metal level in the vacuum chamber is determined, for example, using ultrasonic sensors.

 The application of the proposed method allows to increase the productivity of the process of continuous metal evacuation of the metal by 8% at high efficiency due to periodic recovery and maintaining the volume of the internal working cavity of the vacuum chamber unchanged. The economic effect is calculated in comparison with the base object, for which the method of continuous metal evacuation during continuous casting, adopted at the Novolipetsk Metallurgical Plant, is accepted.

Claims (2)

 1. A method of continuous metal evacuation of a metal during continuous casting, including supplying liquid metal from a casting ladle to a vacuum chamber, creating residual pressure in it, processing the metal in a vacuum chamber, supplying metal from it to an intermediate ladle under a level through a drain pipe and then to molds, characterized in that during the casting periodically, the metal level in the vacuum chamber is raised by reducing the velocity of the metal stream through the drain pipe within 10-60% of the operating value directly proportional to the mass flow of metal from the ladle.  2. Device for continuous metal evacuation during continuous casting, comprising a vacuum chamber with a drain pipe installed in its bottom and included in the intermediate ladle, characterized in that the drain pipe is made with an electromagnetic brake.

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