An electroslag remelting furnace with mold feeding function

Abstract

The present invention relates to an electroslag remelting furnace with a crystallizer wire feeding function, and belongs to the field of metallurgical equipment. The electroslag remelting furnace with a crystallizer wire feeding function provided by the present invention stirs the inside of the crystallizer through an eccentric rotating motor, moves the conductive cross arm up and down relative to the column through a lifting motor, and replenishes the reducing agent inside the crystallizer through a wire feeding pipe inside the rotating motor. The present invention can make the reducing agent addition inside the electroslag furnace continuously controllable, so that the rare earth elements are evenly distributed in the longitudinal direction of the electroslag ingot, and the present invention can ensure that the reducing agent concentration and temperature inside the crystallizer remain stable through the eccentrically rotating consumable electrode.

Description

Technical Field

[0001] The invention relates to an electroslag remelting furnace with a crystallizer wire feeding function, belonging to the field of metallurgical equipment. Background Art

[0002] Rare earth elements are common modifiers for alloy materials, which can refine the solidification structure of alloy materials, improve segregation, refine grains, modify inclusions, etc. The traditional method of adding rare earths is generally completed before or during the casting of consumable electrodes. However, since rare earths are very easy to oxidize, the rare earth elements in the consumable electrodes will face severe oxidation during the electroslag remelting process, resulting in an extremely low recovery rate of rare earth elements in the alloy after electroslag remelting.

[0003] The purpose of rare earth modification of alloys during the electroslag remelting process can be achieved by electroslag remelting of slag containing rare earth oxides and adding a reducing agent to reduce the rare earth oxides in the slag so that the rare earth elements are transferred to the alloy. Rare earth modification in this way can greatly avoid the burning of rare earth elements during the remelting process. On the other hand, the relatively low price of rare earth oxides also makes this rare earth addition method have certain cost advantages.

[0004] Since the consumable electrode of the traditional electric slag furnace is in the center of the crystallizer, the reducing agent can only be added through the gap between the crystallizer and the consumable electrode, such as the disclosed CN201922470991 - a wire feeding device and an electric slag furnace with the device, the reducing agent is added to the electric slag furnace through the wire feeding device, but this technical solution makes the reduction effect at the edge of the slag pool stronger than that in the center of the slag pool, so the metal liquid at the edge of the end where the consumable electrode is inserted into the slag pool after the transition through the slag pool obtains more rare earth elements than the core of the consumable electrode, and due to the strong cooling effect of the water-cooled crystallizer of the electric slag furnace, the diffusion of rare earth elements in the molten metal pool is suppressed, which ultimately leads to the rare earth elements at the edge of the electric slag ingot being higher than the core. The structural characteristics of the traditional electric slag furnace limit the application prospects of this rare earth addition method. How to improve the traditional electric slag furnace to adapt to this rare earth addition method is a problem that needs to be solved at present. Summary of the invention

[0005] In order to solve the problems existing in the above-mentioned prior art, the present invention provides an electroslag remelting furnace with a crystallizer wire feeding function. The present invention can make the reducing agent addition inside the electroslag furnace continuously controllable, so that the rare earth elements are evenly distributed in the longitudinal direction of the electroslag ingot, and the present invention can ensure that the reducing agent concentration and temperature inside the crystallizer remain stable through the eccentrically rotating consumable electrode.

[0006] To achieve the above-mentioned purpose, the technical solution provided by the present invention is: an electroslag remelting furnace with a crystallizer wire feeding function, at least comprising a concrete support platform and a crystallizer for performing redox reactions, the crystallization cavity of the crystallizer is a hollow cylindrical structure without a top cover, the crystallizer is fixed on the concrete support platform, a column is vertically provided on one side of the support platform, a conductive cross arm is horizontally installed on the column, a sliding conductive cylinder for conducting electricity through liquid metal is provided inside the conductive cross arm, the conductive cross arm is connected to the column through a lifting motor, so that the conductive cross arm moves up and down relative to the column, a hollow cylindrical rotating shaft is installed on the cross arm of the conductive cross arm, the axis of the rotating shaft coincides with the axis of the crystallizer, and a consumable electrode is horizontally provided at the bottom of the rotating shaft A bracket, one end of the bracket is fixed to the bottom of the rotating shaft, and the other end of the bracket is clamped on the upper part of the consumable electrode, so that the consumable electrode is parallel to the rotating shaft and the consumable electrode is located inside the crystallizer, and a spacing is provided between the consumable electrode and the rotating shaft, the consumable electrode is connected to the negative electrode of the power supply through the rotating shaft and the sliding conductive cylinder, the rotating shaft is connected to the rotating motor installed above the conductive cross arm through gears, so that the rotating shaft keeps rotating while driving the consumable electrode to make a revolution relative to the rotating shaft, a wire feeding machine is provided on the concrete support platform, and the wire feeding machine conveys the wire feeding material to the inside of the crystallizer through a liftable wire feeding pipe located at the axial center of the rotating shaft, and the liftable wire feeding pipe is located at the axial center of the crystallizer, so that the wire feeding material passes into the crystallizer through the liftable wire feeding pipe.

[0007] A bottom water tank for cooling and conducting electricity is arranged between the crystallizer and the concrete supporting platform.

[0008] The rotating shaft is connected to a rotating motor which is laterally fixed on a conductive cross arm through a bevel gear.

[0009] A straightening machine for straightening the wire feeding material is arranged between the wire feeding machine and the liftable wire feeding tube.

[0010] The sliding conductive cylinder is nested on the rotating shaft, and the space between the sliding conductive cylinder and the rotating shaft is filled with conductive liquid metal, which is a gallium-based alloy.

[0011] The lifting motor is connected to the column through a speed reducing device, so that the conductive cross arm can move up and down along the column.

[0012] According to the above technical solution, the electroslag remelting furnace with a crystallizer wire feeding function provided by the present invention stirs the inside of the crystallizer through an eccentric rotating motor, moves the conductive cross arm up and down relative to the column through a lifting motor, and replenishes the reducing agent inside the crystallizer through a wire feeding tube inside the rotating motor. Compared with the prior art solution, the present invention has the following advantages:

[0013] (1) Because the present invention allows the reducing alloy cored wire to be fed into the center of the crystallizer through the eccentric layout of the consumable electrode, and at the same time the eccentric consumable electrode can make a circular motion around the center of the crystallizer, the present invention promotes the stirring of the slag pool through the rotation of the consumable electrode, thereby making the rare earth elements transitioning to the metal molten pool evenly distributed.

[0014] (2) Because the wire feeding material is straightened by the straightening machine and then fed into the center of the crystallizer through a liftable wire feeding tube by the wire feeding machine, the reducing agent alloy cored wire feeding function of the present invention makes the addition of the reducing agent more continuous and controllable, thereby making the rare earth elements evenly distributed in the longitudinal direction of the electroslag ingot.

[0015] (3) Due to the eccentric layout of the consumable electrode of the present invention, the consumable electrode moves in a circle around the center of the crystallizer, and the rotation effect of the consumable electrode can play a role in stirring the slag pool, so the present invention can improve the temperature field distribution of the slag pool, which is conducive to forming a shallower metal molten pool. The shallow metal molten pool can promote the directional solidification of the electroslag ingot and is conducive to improving the segregation of the electroslag ingot. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a structural schematic diagram of an eccentric rotating electrode electroslag furnace with a crystallizer wire feeding function in the present invention;

[0017] Figure 2 It is a schematic diagram of the partial structure of the conductive cross arm and the conductive material rod;

[0018] In the figure: 1. bottom water tank; 2. crystallizer; 3. consumable electrode; 4. bracket; 5. conductive cross arm; 6. liftable wire feeding tube; 7. column; 8. lifting motor; 9. wire feeding machine; 10. concrete support platform; 11. slag pool; 12. metal ingot; 13. sliding conductive cylinder; 14. rotating bearing; 15. rotating bevel gear; 16. transmission bevel gear; 17. rotating motor; 18. rotating shaft. DETAILED DESCRIPTION

[0019] The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments, but the protection scope of the present invention is not limited to the following embodiments.

[0020] In the technical solution provided by the present invention, an electroslag remelting furnace with a crystallizer wire feeding function is provided. Figure 1 and Figure 2As shown, it at least includes a concrete support platform 10 and a crystallizer 2 for performing redox reaction. The crystallization cavity of the crystallizer 2 is a hollow cylindrical structure without an upper cover. The crystallizer 2 is fixed on the concrete support platform 10. The inside of the crystallizer 2 is a slag pool 11 containing a metal ingot 12. A bottom water tank 1 for cooling and conducting electricity is provided between the crystallizer 2 and the concrete support platform 10. An ingot starter plate is provided on the bottom water tank 1, and an arc starter is provided on the ingot starter plate.

[0021] A column 7 is vertically provided on one side of the support platform, and a conductive cross arm 5 is horizontally installed on the column 7. The lifting motor 8 is connected to the column 7 through a reduction device, so that the conductive cross arm 5 can move up and down along the column 7. A sliding conductive cylinder 13 that conducts electricity through liquid metal is provided inside the conductive cross arm 5. The conductive cross arm 5 is connected to the column 7 through the lifting motor 8, so that the conductive cross arm 5 moves up and down relative to the column 7. A hollow cylindrical rotating shaft 18 is installed on the cross arm of the conductive cross arm 5, and a corrosion-resistant rotating bearing 14 is provided between the conductive cross arm 5 and the rotating shaft 18. The axis of the rotating shaft 18 coincides with the axis of the crystallizer 2, and the rotating shaft 18 is connected to the rotating motor horizontally fixed to the conductive cross arm 5 through a bevel gear. The sliding conductive cylinder 13 is nested on the rotating shaft 18, and the space between the sliding conductive cylinder 13 and the rotating shaft 18 is filled with conductive liquid metal, and the conductive liquid metal is a gallium-based alloy.

[0022] A bracket 4 for clamping the consumable electrode 3 is transversely provided at the bottom of the rotating shaft 18, one end of the bracket 4 is fixed at the bottom of the rotating shaft 18, and the other end of the bracket 4 is clamped on the upper part of the consumable electrode 3, so that the consumable electrode 3 is parallel to the rotating shaft 18 and the consumable electrode 3 is located inside the crystallizer 2, and a spacing is provided between the consumable electrode 3 and the rotating shaft 18, the consumable electrode 3 is connected to the negative pole of the power supply through the rotating shaft 18 and the sliding conductive cylinder 13, the rotating shaft 18 is connected to the rotating motor 17 installed above the conductive cross arm 5 through gears, so that the rotating shaft 18 keeps rotating while driving the consumable electrode 3 to make an orbital motion relative to the rotating shaft 18, a rotating bevel gear 15 is transversely provided on the rotating shaft 18, and a transmission bevel gear 16 matching the rotating bevel gear 15 is fixed on the rotating motor transversely fixed on the conductive cross arm 5, and the transmission ratio of the transmission bevel gear 16 to the rotating bevel gear 15 is 1:3.

[0023] A wire feeder 9 is provided on the concrete support platform 10. The wire feeder 9 conveys the wire feed material to the inside of the crystallizer 2 through a liftable wire feeder pipe 6 located at the axial center of the rotating shaft 18. The liftable wire feeder pipe 6 is located at the axial center of the crystallizer 2, so that the wire feed material passes into the crystallizer 2 through the liftable wire feeder pipe 6. A straightening machine for straightening the wire feed material is provided between the wire feeder 9 and the liftable wire feeder pipe 6.

[0024] In Example 1 provided by the present invention, Figure 1As shown, the diameter of the crystallizer 2 is 360 mm, the diameter of the consumable electrode 3 is 120 mm, the axis of the consumable electrode 3 is 90 mm away from the axis of the crystallizer 2, the outer diameter of the liftable wire feeding tube 6 is 20 mm, the channel diameter of the center of the rotating shaft 18 is 30 mm, and the conductive liquid metal filled in the sliding conductive cylinder 13 is a gallium-indium-tin alloy, in which gallium accounts for 68.5%, indium accounts for 21.5%, and tin accounts for 10% (by weight), and its melting point is 10°C.

[0025] The metal to be remelted in this embodiment 1 is H13 hot working die steel, and the eccentric rotating electrode electroslag furnace with a crystallizer wire feeding function is provided to perform the remelting operation according to the following steps:

[0026] Step 1: In this embodiment, the total weight of the H13 consumable electrode 3 is 1000 kg, and the consumable electrode 3 needs to be descaled before the electroslag remelting operation.

[0027] Step 2: In this embodiment, the slag system used in the electroslag remelting process is a quaternary slag system of CaF2-CeO2-CaO-Al2O3, and the total weight of the slag is 45 kg, of which CaF2 accounts for 45%, CeO2 accounts for 30%, CaO accounts for 20%, and Al2O3 accounts for 5% (weight ratio). The solid slag is first baked in a heating furnace at 600°C for 2 hours.

[0028] Step 3: Place a starter plate on the bottom water tank 1, and place 1 kg of CaF2-TiO2 arc starter on the starter plate. Then hang the crystallizer 2 on the bottom water tank 1 and connect the cooling water.

[0029] Step 4: After inserting the graphite electrode into the crystallizer 2, add a small amount of dried slag, and start the arc with a furnace voltage of 45V and a current of 4000A. After the arc is successfully started, quickly add the remaining slag, and remove the graphite electrode after the slag is completely melted and kept warm for 20 minutes.

[0030] Step 5: Use a conductive electrode to clamp the H13 steel consumable electrode 3, lower the consumable electrode 3 into the slag pool 11 through the lifting motor 8, and start the electroslag remelting process with a furnace port voltage of 50V and a remelting current of 6000A.

[0031] Step 6: Operate the electric control system of the rotating motor 17 to drive the rotating shaft 18 to rotate at a constant speed of 10 rpm.

[0032] Step 7: Operate the wire feeder 9 to feed the CaSi alloy cored wire into the slag pool 11 at a speed of 3 g / min. The CaSi alloy cored wire contains 30% Ca, 55% Si, 8.5% Fe, and 1.9% Al (by weight), and the remainder is unavoidable impurities.

[0033] Step 8: After the H13 steel consumable electrode 3 is remelted, the rotating motor 17 and the wire feeder 9 are turned off, and the metal ingot 12 is demoulded after cooling, and the demoulded metal ingot 12 is buried in a sand pit for slow cooling for 72 hours.

[0034] Samples were taken from the center, 1 / 2 radius and edge of the lower, middle and upper parts of the steel ingot, and the Ce content in each sampling part was analyzed by inductively coupled plasma emission spectrometer.

[0035] In addition, H13 steel remelted in a conventional electroslag furnace with a mold 2 having a diameter of 360 mm was used as a comparison, using slag of the same composition and the same amount of CaSi alloy addition, except that 30 g of CaSi alloy was added to the slag pool 11 every 10 minutes by manual addition in the gap between the consumable electrode 3 and the crystallizer 2. Samples were taken from the same part of the H13 electroslag ingot after remelting, and the Ce element content in the steel was analyzed using an inductively coupled plasma emission spectrometer.

[0036] Table 1 shows the Ce content of different parts of the H13 electroslag ingot (marked as M) remelted using the present invention and the H13 electroslag ingot (marked as T) remelted using a traditional electroslag furnace. It can be seen that the radial distribution of Ce in the H13 electroslag ingot remelted using a traditional electroslag remelting furnace has a serious uneven distribution phenomenon, and the Ce content of the edge of the electroslag ingot is much higher than that of the core of the electroslag ingot. This is caused by the layout in which the consumable electrode 3 in the traditional electroslag remelting furnace can only be fixed in the center of the crystallizer 2. The uniformity of the radial distribution of Ce in the H13 electroslag ingot remelted using the eccentric rotating electrode electroslag furnace with a crystallizer wire feeding function of the present invention has been significantly improved.

[0037] Table 1 Ce content in different parts of H13 steel (wt.%)

[0038]

[0039] In Example 2 provided by the present invention, the diameter of the crystallizer 2 is 500 mm, the diameter of the consumable electrode 3 is 180 mm, and the axis of the consumable electrode 3 is 120 mm away from the axis of the crystallizer 2. This example is for 8Cr13MoV stainless steel to be subjected to electroslag remelting rare earth La modification treatment, and the total weight of the 8Cr13MoV consumable electrode 3 is 2000 kg. The specific steps are as follows:

[0040] Step 1: Before the electroslag remelting operation, the consumable electrode 3 needs to be descaled.

[0041] Step 2: The remelting uses a quaternary slag system of CaF2-La2O3-CaO-Al2O3, in which CaF2 accounts for 45%, La2O3 accounts for 25%, CaO accounts for 22.5%, and Al2O3 accounts for 7.5% (by weight), and the slag amount is 90 kg. The solid slag is baked in a heating furnace at 600°C for 5 hours.

[0042] Step 3: Place a starter plate on the bottom water tank 1, and place 1.5 kg of CaF2-TiO2 arc starter on the starter plate. Then hang the crystallizer 2 on the bottom water tank 1, and then connect the cooling water.

[0043] Step 4: After inserting the graphite electrode into the crystallizer 2, add a small amount of dried slag, and start the arc with a furnace voltage of 50V and a current of 5000A. After the arc is successfully started, quickly add the remaining slag, and remove the graphite electrode after the slag is completely melted and kept warm for 20 minutes.

[0044] Step 5: Use a conductive electrode to clamp the consumable electrode 3, lower the consumable electrode 3 into the slag pool 11 through the lifting motor 8, and start the electroslag remelting process with a furnace port voltage of 60V and a remelting current of 9000A.

[0045] Step 6: Operate the electric control system of the rotating motor 17 to drive the rotating shaft 18 to rotate at a constant speed of 10 rpm.

[0046] Step 7: Operate the wire feeder 9 to feed the CaSi alloy cored wire into the slag pool 11 at a speed of 6 g / min. The composition of the CaSi alloy cored wire is consistent with that of Example 1.

[0047] Step 8: After the consumable electrode 3 is remelted, the rotary motor 17 and the wire feeder 9 are turned off, and the metal ingot 12 is demoulded after cooling. The demoulded metal ingot 12 is buried in a sand pit for slow cooling for 72 hours.

[0048] Samples were taken at the center, 1 / 2 radius and edge of the lower, middle and upper parts of the metal ingot 12, and the La content in each sampling part was analyzed by inductively coupled plasma emission spectrometer. The results are shown in Table 2, which shows that when remelting 8Cr13MoV steel, the effect of uniformly transitioning rare earth elements into the steel can also be achieved.

[0049] Table 2 La content in different parts of 8Cr13MoV steel (wt.%)

[0050] Center Radius 1 / 2 edge upper part 0.0068 0.0067 0.0061 Central 0.0076 0.0073 0.0069 lower part 0.0085 0.0083 0.0079

[0051] The eccentric rotating electrode electroslag furnace with a crystallizer wire feeding function provided in Examples 1 and 2 is simple to operate, stable and reliable, and has a high degree of automation. It is suitable for the electroslag remelting process of transitioning rare earth elements to the remelted alloy by adding rare earth slag in combination with reducing agents. The rare earth elements in the electroslag ingots obtained by remelting are relatively evenly distributed, and good rare earth modification effects are achieved in electroslag ingots of different diameters.

Claims

1. An electroslag remelting furnace with a crystallizer wire feeding function, comprising at least a concrete support platform and a crystallizer for performing redox reactions, characterized in that: The crystallization cavity of the crystallizer is a hollow cylindrical structure without a top cover. The crystallizer is fixed on a concrete support platform. A column is vertically arranged on one side of the support platform. A conductive cross arm is horizontally installed on the column. A sliding conductive cylinder for conducting electricity through liquid metal is arranged inside the conductive cross arm. The conductive cross arm is connected to the column through a lifting motor so that the conductive cross arm moves up and down relative to the column. A cylindrical rotating shaft is installed on the cross arm of the conductive cross arm. The axis of the rotating shaft coincides with the axis of the crystallizer. A bracket for clamping a consumable electrode is horizontally arranged at the bottom of the rotating shaft. One end of the bracket is fixed to the bottom of the rotating shaft, and the other end of the bracket is clamped on the upper part of the consumable electrode. , so that the consumable electrode is parallel to the rotating axis and the consumable electrode is located inside the crystallizer, a gap is set between the consumable electrode and the rotating axis, the consumable electrode is connected to the negative electrode of the power supply through the rotating axis and the sliding conductive cylinder, the rotating axis is connected to the rotating motor installed above the conductive cross arm through a bevel gear, so that the rotating axis keeps rotating while driving the consumable electrode to make a revolution relative to the rotating axis, a wire feeding machine is provided on the concrete support platform, the wire feeding machine conveys the wire feeding material to the inside of the crystallizer through a liftable wire feeding tube located at the axis center of the rotating axis, the liftable wire feeding tube is located at the axis center of the crystallizer, so that the wire feeding material passes into the crystallizer through the liftable wire feeding tube.

2. The electroslag remelting furnace with a crystallizer wire feeding function according to claim 1, characterized in that: A bottom water tank for cooling and conducting electricity is arranged between the crystallizer and the concrete supporting platform.

3. The electroslag remelting furnace with a crystallizer wire feeding function according to claim 1, characterized in that: A straightening machine for straightening the wire feeding material is arranged between the wire feeding machine and the liftable wire feeding tube.

4. The electroslag remelting furnace with a crystallizer wire feeding function according to claim 1, characterized in that: The sliding conductive cylinder is nested on the rotating shaft, and the space between the sliding conductive cylinder and the rotating shaft is filled with conductive liquid metal, which is a gallium-based alloy.

5. The electroslag remelting furnace with a crystallizer wire feeding function according to claim 1, characterized in that: The lifting motor is connected to the column through a speed reducing device, so that the conductive cross arm can move up and down along the column.

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