Vacuum melting furnace body device and knotting method thereof

Abstract

The present application relates to the field of vacuum furnace body knotting manufacturing, in particular to a vacuum smelting furnace body device and a knotting method thereof. The device comprises a plurality of copper wire groups, which are laid between a tire membrane (2) and an asbestos cloth (4) and close to the inner side of the asbestos cloth (4) at intervals. The copper wire group comprises a plurality of first copper wires and a plurality of second copper wires (6), and the second copper wires (6) are arranged in a staggered and buckled manner with the first copper wires (7) embedded in the lower layer. The use of the method of the present application overcomes the defects of low bonding strength and easy crack formation at the connecting parts between the main induction zone and the furnace ring, and between the furnace ring and the furnace nozzle of the existing furnace body, enhances the connection integrity and firmness between the main induction zone and the furnace ring, and between the furnace ring and the furnace nozzle, reduces the occurrence of large transverse and longitudinal crack defects, improves the service life and production efficiency of the vacuum furnace body, reduces the knotting frequency of the furnace body under the same production condition, and reduces the labor intensity of personnel.

Description

Technical Field

[0001] This invention relates to the field of vacuum furnace body knotting manufacturing, specifically to a vacuum smelting furnace body device and its knotting method. Background Technology

[0002] Currently, the 200kg vacuum induction furnace can be used for smelting various low, medium, and high alloy steels, non-ferrous metals, rare earth permanent magnets, nickel-based, iron-based, cobalt-based, and other high-precision alloys or high-purity metals. The ultimate vacuum level can reach 6.6×10⁻² Pa. Continuous feeding, alloying, temperature measurement, and sampling can be achieved under vacuum. The internationally advanced American Leitai dual-colorimetric thermometer is used for temperature measurement, and casting can be completed under vacuum. Furnace body bridging involves filling and compacting a dry powder and granular mixture of high-temperature resistant materials between the induction coil (lined with asbestos cloth), the furnace bottom, and the steel inner liner. The bridging process requires a high degree of uniformity in compaction; improper control can seriously affect the furnace's service life and the safety of personnel and equipment. During operation, furnace body bridging is typically achieved by manually striking a self-made punch (T-shaped rod) with a hammer to compact the loose material added to the furnace body. This operating method is labor-intensive, requiring multiple people to operate simultaneously and in shifts. The compaction effect fluctuates significantly with personnel changes, and the compaction effect decreases with varying levels of fatigue due to the long furnace body tying time. Furthermore, the dust generated during feeding and tying, caused by multiple people being near the feeding port at the same time, poses a hazard to many individuals.

[0003] Currently, the furnace body formed by the knotting process in electromagnetic induction vacuum smelting furnaces often experiences steel splashing and boiling due to various factors during use. Metal adheres to the inner wall and upper part of the furnace collar, as well as the inner wall, upper part, and end of the tapping trough nozzle. Since the junction between the main induction zone and the furnace collar is a point where dry and wet materials meet (the furnace collar charge requires a certain wet strength and contains a certain proportion of water glass and clay), it is a weak point. During the cleaning operation after each smelting, these areas are easily subjected to mechanical stress. The knotting process, involving two different proportions of furnace charge, is then dried... After sintering, the different properties prevent the force from being evenly transmitted downwards at the joint. The expansion and contraction of the joint due to temperature changes cause local or overall transverse or longitudinal cracks at the joint between the upper part of the main induction zone and the furnace collar, further aggravating the defects in the furnace body. At the same time, due to its special position and structure, the tapping trough nozzle protrudes outwards from the furnace collar and has no support at the bottom. It is also prone to cracking or falling off from the main body due to external forces, affecting the life of the knotted furnace body. Under the same output conditions, the number of times the furnace body is knotted can be increased, resulting in high labor intensity and low production efficiency.

[0004] Patent application CN101545723 A discloses a method for tamping the furnace lining of an induction furnace using a tamping machine. The method involves using a tamping hammer, positioned horizontally and unchanged, to longitudinally pound tamping material in a horizontally rotating mold 2 to shape the furnace lining. The mold is fixedly mounted on a rotating worktable at the bottom of the tamping machine, and the tamping hammer is mounted above the rotating worktable. The key feature is that the rotation speed of the rotating worktable is 5 revolutions per minute. 15 revolutions per minute, with the tamping rate of the tamping hammer at 250 times per minute. At 700 times per minute, the optimal combination of the rotation speed of the rotary table and the tamping speed of the tamping hammer ensures continuous, uniform, and moderate tamping of the tamping material, resulting in a smooth, spiral-shaped bonded furnace liner with a density greater than or equal to 2.85 g / cm³. While this patent also relates to the processing technology of induction furnace liner, the size and application scope of the furnace are not suitable for the steelmaking field. Even if the rotary table and tamping machine could be scaled up to a certain extent, the subsequent removal of the mold and the tamped furnace liner would not be suitable for medium-frequency furnaces used in steelmaking. Furthermore, the rotary stamping process could potentially cause mechanical damage to the asbestos-lined induction coil, leading to maintenance difficulties.

[0005] Patent application CN201288161 A describes a tamping hammer for a coking oven tamping machine, relating to supporting equipment for coking ovens. Existing tamping hammers use I-beams as the main body of the hammer rod, resulting in low rigidity and poor stability. Furthermore, tamping hammers suffer from drawbacks such as the hammer head being difficult to lift when buried in the raw coal and coal sticking to the bottom of the hammer head, affecting the normal operation of the tamping machine. This utility model includes: a hammer rod, a hammer head connected to the hammer rod, and friction plates connected to both sides of the hammer rod. The hammer rod described in this patent uses an HN250X 125 type steel structure; a transition conical guard plate is provided at the connection between the hammer rod and the hammer head; and a stainless steel plate is welded to the bottom surface of the hammer head, thus achieving the characteristics of a lightweight tamping hammer, good stability, and less burial and adhesion of the hammer head to coal. However, this patent relates to a tamping hammer with high tamping strength, and is not suitable for tamping the furnace body of a medium-frequency furnace.

[0006] Patent application CN105174976A, entitled "Method for Casting Lining of Straight-Cylinder Furnace for Ferrovanadium Alloy Smelting," discloses a method for casting lining of a straight-cylinder furnace for ferrovanadium alloy smelting. The casting method includes the following steps: directly pouring a uniformly mixed castable into the furnace shell; stirring the castable until the castable at the furnace bottom and on the furnace side walls is compacted and flat; air-drying followed by baking; and then cooling before knotting the lining at the furnace bottom and on the furnace side walls. This invention uses castable instead of magnesia bricks for direct integral casting at the furnace bottom. While this reduces the amount of magnesia sand used for knotting and lowers refractory material consumption, the casting method of the above invention does not involve reinforcing ribs during the furnace lining knotting process. It is a conventional knotting process and still has shortcomings in addressing furnace lining cracks, the integrity and strength of the connection between the furnace nozzle and the furnace collar, and the overall strength of the furnace body is not high. Summary of the Invention

[0007] The purpose of this invention is to provide a new and improved method for the sintering process of a vacuum smelting furnace body, which can be used in the sintering and forming process of induction vacuum smelting furnace bodies with a capacity of 200 kg or less (including 200 kg level) for smelting various metals.

[0008] To achieve the above objectives, the present invention provides a vacuum smelting furnace body device, the device comprising a plurality of copper wire groups, the plurality of copper wire groups being laid at intervals between the membrane 2 and the asbestos cloth 4 and close to the inner side of the asbestos cloth 4, the copper wire groups comprising a plurality of first copper wires and a plurality of second copper wires 6, the second copper wires 6 being staggered and interlocked with the first copper wires 7 pre-embedded in the lower layer.

[0009] Preferably, the first copper wire 7 and the second copper wire 6 are both U-shaped copper wires with arcs at both ends, and the bending curvature of the U-shaped copper wire matches the curvature of the furnace body induction coil.

[0010] Preferably, the second copper wire 6 is staggered and interlocked with the first copper wire 7 pre-embedded in the lower layer in the opposite direction.

[0011] Preferably, the copper wire groups are laid at intervals between the membrane 2 and the asbestos cloth 4, and are located at a position one-quarter to two-fifths of the way from the inner side of the asbestos cloth.

[0012] Preferably, a third copper wire 9 is provided on both sides of the steel outlet of the vacuum smelting furnace body and at both ends of the upper and lower layers for connecting the furnace collar and the steel outlet nozzle.

[0013] Preferably, the third copper wire 9 is a copper wire with loops at both ends.

[0014] This invention provides a method for knotting the furnace body of a vacuum smelting furnace, comprising the following steps:

[0015] 1) When the furnace body is knotted to the layer of filler before the main induction zone and the furnace collar 1 are combined, a number of first copper wires 7 are laid at intervals between the membrane 2 and the heat insulation asbestos cloth 4, close to the inner side of the heat insulation asbestos cloth 4.

[0016] 2) Then fill the knotted dry material, add the bottom layer of furnace material, and interlock the second copper wire 6 with the first copper wire 7 pre-embedded in the lower layer in the opposite direction, and then knot the bottom layer of furnace material.

[0017] 3) When the knot is tied to the tapping spout 10, the third copper wire 9, which is set on both sides of the tapping spout and in the upper and lower layers, is introduced.

[0018] Preferably, in step 1), the first copper wire 7 is laid at intervals between the membrane 2 and the asbestos cloth 4 and is located at a position one-quarter to two-fifths of the way from the inner side of the asbestos cloth.

[0019] Preferably, in step 2), the first copper wire 6 is evenly laid between the membrane 2 and the asbestos cloth 4 and is located at a position one-quarter to two-fifths of the way from the inner side of the asbestos cloth.

[0020] Preferably, in step 3), a third copper wire 3 is introduced from the furnace head 1 to the tapping trough according to the shape of the tapping trough nozzle.

[0021] Based on the type of induction vacuum furnace, select appropriate filling materials for furnace breaking, as well as round steel inner liner and furnace bottom pad of suitable size, and make several wide near-U-shaped copper wires and spiral hook copper wires (the thickness of the copper wires depends on the specific furnace conditions).

[0022] The furnace body knotting process involves filling and compacting a mixture of dry powder and granular high-temperature resistant materials between the circular induction coil 3 (lined with heat-insulating asbestos cloth 4), the furnace bottom 5, and the circular steel inner liner 8. When the furnace body is knotted to the layer of filler material before the main induction zone and furnace collar 1 are joined, pre-bent, wide, near-U-shaped copper wires 7 (the wire thickness depends on the specific furnace conditions) are laid between the membrane 2 and the heat-insulating asbestos cloth 4, approximately one-third of the way from the inner side of the asbestos cloth 4 (the temperature near the asbestos cloth is relatively low, so it will not affect the strength of the copper wire during smelting). These wires are evenly distributed, with appropriate intervals between each wide, near-U-shaped bent copper wire. The bending arc is similar to the arc of the furnace body induction coil. Then, the knotted dry material is filled and compacted, and the bottom layer of furnace collar material is added. Another U-shaped copper wire 6, which has been pre-bent, is interlocked with the U-shaped copper wire 7 pre-embedded in the lower layer in a staggered manner, with appropriate spacing in all directions. It is evenly laid between the membrane 2 and the heat-insulating asbestos cloth 4, at the inner third position of the asbestos cloth. Then, the bottom layer of the furnace charge is knotted. When the knotting reaches the position of the tapping trough nozzle 10, according to the shape of the tapping trough nozzle, copper wires 9 with loop hooks at both ends, which are distributed on both sides of the tapping opening and on both the upper and lower layers, are introduced from the furnace charge to the tapping trough as reinforcing ribs to make the connection between the furnace charge and the tapping trough nozzle more secure and reliable.

[0023] Compared with the prior art, the advantages of the present invention are:

[0024] The method of this invention overcomes the defects of existing furnaces, such as low bonding strength and easy cracking at the connection points between the main induction zone and the furnace ring, and between the furnace ring and the nozzle. It enhances the integrity and robustness of the connection between the main induction zone and the furnace ring, and between the furnace ring and the nozzle, reducing the occurrence of large transverse and longitudinal cracks, improving the service life and production efficiency of the vacuum furnace, and reducing the number of times the furnace body needs to be knotted for the same output, thus reducing the labor intensity of personnel. This invention does not require additional auxiliary equipment to complete the knotting process; the U-shaped copper wire fabrication is simple and easy to operate, greatly increasing the safety, reliability, and stability of the furnace body during use. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the furnace body structure.

[0026] Figure 2 A schematic diagram of the U-shaped copper wire used as a reinforcing rib in the furnace lining.

[0027] Figure 3 This is a schematic diagram of the copper wire reinforcing ribs of the furnace nozzle and furnace collar.

[0028] Figure 4 A top-view schematic diagram of the internal furnace body, furnace collar, and tapping trough / nose structure.

[0029] Figure label:

[0030] 1. Furnace collar; 2. Furnace membrane and filler; 3. Induction coil; 4. Asbestos cloth; 5. Furnace bottom pad; 6. Type II copper wire; 7. Type I copper wire; 8. Circular steel inner liner; 9. Type III copper wire; 10. Steel tapping trough nozzle. Detailed Implementation

[0031] The present invention will be further described below with reference to specific embodiments.

[0032] To enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in the embodiments of this application are clearly and completely described below. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this application.

[0033] This invention provides a process for sintering the furnace body of a vacuum smelting furnace, as shown in the attached figure. Figure 1-4 As shown.

[0034] First, fix the jack to the furnace bottom pad bracket to prevent the furnace body from shifting downwards due to the hammering of the furnace charge during tamping. Then, place the furnace bottom pad 5 lined with asbestos cloth 4 on the bracket, centered (when placing, check that the bracket and tray are flat and reliable to prevent the pad from breaking due to uneven force during tamping). After the pad 5 is in place, lay the vacuum furnace induction coil 3 along with the furnace bottom pad 5 and cover it with heat-insulating asbestos cloth 4 (ensure that the overlap is flat and that no asbestos fibers are exposed). After the asbestos cloth 4 is laid, spread the pre-prepared filler material 50 mm thick on the furnace bottom asbestos cloth and tamp it down. Ensure that the entire bottom surface is compact and uniform, and prevent the furnace charge from entering the overlap areas of the asbestos cloth on the sides (the same applies below). After the first layer is completed, add another layer and compact it. After tamping and smoothing, the overall thickness of the furnace body should be controlled at 80 mm. Then, the pre-made circular steel inner liner 8 is placed on the bottom of the furnace bottom bridging material, with the placement of the circular steel inner liner 8 coinciding with the center line of the circular induction coil. After the circular steel inner liner 8 is placed, a counterweight is added inside the inner liner for fixation. Three wooden wedges are added along the upper edge of the inner liner 8 to support the coil 3, which is attached to the asbestos cloth 4. A bridging furnace body membrane 2 is formed between the circular induction coil 3 (lined with heat-insulating asbestos cloth 4) and the circular steel inner liner 8 in the height direction. Dry powder and granular mixed high-temperature resistant material is filled and compacted layer by layer in the membrane 2. The thickness of each layer is no more than 50 mm, and the filling is compact and uniform, with good connection between layers. When the dry-mixed high-temperature resistant material is knotted to a depth of 65 mm from the upper edge of the induction coil 3, i.e., the layer of filler before the main induction zone is combined with the furnace collar 1, the pre-bent, arc-shaped, wide, near-U-shaped first copper wire 7 is laid between the membrane and the heat-insulating asbestos cloth, about one-third of the way from the inner side of the asbestos cloth, and evenly distributed. Each wide, near-U-shaped first copper wire 7 has an appropriate interval, and the bending arc is similar to the arc of the coil 3. Then, the knotted dry material is filled and compacted. After adding the bottom layer of furnace collar material, another pre-bent U-shaped second copper wire 6 is interlocked with the lower layer of pre-embedded U-shaped first copper wire 7 in the opposite direction (see...). Figure 2The material is evenly laid between the membrane 2 and the asbestos cloth 4, with moderate spacing in all directions, near the inner third of the asbestos cloth 4. Then, the bottom layer of the furnace charge is knotted. (The furnace charge is made by remixing dry refractory material with water glass and an appropriate amount of clay, possessing a certain wet strength. The knotting is completed when it reaches 30 to 50 millimeters above the top of the water-cooled coil 3.) Finally, the tapping spout 10 is knotted at an appropriate position on the furnace charge 1. The pre-prepared copper tapping spout base is placed in the appropriate position, with one end near the furnace body protruding into the inner side of the induction coil asbestos cloth 4, and secured tightly with furnace charge. A bottom layer of material with wet... The furnace charge is prepared with sufficient strength and compacted appropriately. Then, according to the shape of the tapping trough nozzle 10, third copper wire 9, with loop-shaped hooks, is introduced from the furnace charge 1 to the tapping trough 10 as reinforcing ribs, located on both sides of the lower part of the tapping opening. The furnace charge is added and compacted to form the bottom shape of the tapping trough. When it reaches the left and right ends of the tapping opening, the third copper wire 9 with loop-shaped hooks is introduced again from the furnace charge. The furnace charge is then added to form the tapping trough nozzle, and the tapping trough area is dried with carbon dioxide to achieve dry strength. In summary, all steps of the furnace body tying process of the vacuum smelting furnace involved in this invention are completed, realizing the application and implementation of the core process method of this invention.

[0035] This invention overcomes the defects of existing furnaces, such as low bonding strength and easy cracking at the connection between the main induction zone and the furnace leader, and between the furnace leader and the burner nozzle. It enhances the integrity and robustness of the connection between the main induction zone and the furnace leader, and between the furnace leader and the burner nozzle, reduces the generation of large transverse and longitudinal cracks, and improves the service life and production efficiency of the vacuum furnace.

[0036] All aspects not described in detail in this invention can be covered using conventional technical knowledge in the field.

[0037] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to the embodiments, those skilled in the art should understand that modifications or equivalent substitutions to the technical solutions of the present invention do not depart from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for tying the furnace body of a vacuum smelting furnace, comprising the following steps: 1) The vacuum smelting furnace body device includes several copper wire groups, which are laid at intervals between the membrane (2) and the asbestos cloth (4) and close to the inner side of the asbestos cloth (4). The copper wire groups include several first copper wires (7) and several second copper wires (6). When the furnace body is knotted to the layer of filler before the main induction zone and the furnace collar (1) are combined, several first copper wires (7) are laid at intervals between the membrane (2) and the heat-insulating asbestos cloth (4) and close to the inner side of the heat-insulating asbestos cloth (4). 2) Then fill the knotted dry material, add the bottom furnace material, and set the second copper wire (6) in the opposite direction to the first copper wire (7) pre-embedded in the lower layer, and then knot the bottom layer of the furnace material; 3) When the knot is tied to the tapping spout (10), the third copper wire (9) is introduced, which is located on both sides of the tapping spout and in the upper and lower layers. The first copper wire (7) and the second copper wire (6) are both U-shaped copper wires with arcs at both ends. The bending arc of the U-shaped copper wire matches the arc of the furnace body induction coil. The third copper wire (9) is a copper wire with loop hooks at both ends. The vacuum smelting furnace body has a third copper wire (9) on both sides of the steel outlet and at both ends of the upper and lower layers for connecting the furnace collar and the steel outlet nozzle.

2. The method for tying the furnace body of a vacuum smelting furnace according to claim 1, characterized in that, In step 1), the first copper wire (7) is laid at intervals between the fetal membrane (2) and the asbestos cloth (4) and is located at a position one-quarter to two-fifths of the inner side of the asbestos cloth.

3. The method for tying the furnace body of a vacuum smelting furnace according to claim 1, characterized in that, In step 2), the second copper wire (6) is evenly laid between the membrane (2) and the asbestos cloth (4) and is located at a position one-quarter to two-fifths of the inner side of the asbestos cloth.

4. The method for tying the furnace body of a vacuum smelting furnace according to claim 1, characterized in that, In step 3), the third copper wire (3) is introduced from the furnace collar (1) to the steel tapping trough according to the shape of the furnace nozzle.

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