Control method for forming bottom of steel ingot through top pouring method of vacuum induction furnace

Abstract

The invention relates to the field of casting steel ingots through a vacuum induction furnace top pouring method. The invention relates to a control method for forming the bottom of a steel ingot by an up-pouring method in a vacuum induction furnace, which comprises the following steps of: preparing an up-down split double-open type ingot mould, a gasket and a fixed ejector rod device, and covering the upper half part of the up-down split double-open type ingot mould on the lower half part of the up-down split double-open type ingot mould and then fixing through a fastening ingot mould bolt; the gasket is composed of a round cake and a round table which are of an integrated structure. The upper half ingot mold is slowly moved away through a crown block, a gasket is vertically placed in the lower half ingot mold, the small end faces the bottom of the ingot mold and is tightly attached to the bottom of the ingot mold, the gasket is fixed through a fixed ejector rod device, and the distance between the maximum diameter of the gasket and the side wall of the lower half ingot mold is 0-2 mm; and the upper half ingot mould is slowly covered on the lower half ingot mould by using a crown block, the head part of the fixed ejector rod device extends out of the sprue gate, the upper half ingot mould and the lower half ingot mould are ensured to be aligned in position and are tightly jointed, and after the positions are determined to be proper, ingot mould bolts are fastened in a diagonal bolt hitting manner.

Description

Technical Field

[0001] This invention relates to the field of casting steel ingots by pouring into a vacuum induction furnace. Background Technology

[0002] Top-pouring is a key technology in metallurgical casting and aerospace engineering. In steel production, it refers to the pouring method where molten steel is directly poured from the top of the ingot mold. In satellite engineering, it involves specific processes for remote data transmission or software updates. A vacuum induction furnace consists of four chambers: a melting chamber, an ingot mold chamber, a charging chamber, and a chute chamber. During the smelting stage, the melting chamber and the ingot mold chamber are separated. During the pouring stage, a gate valve is opened between the two chambers to connect them. When pouring steel in the vacuum induction furnace, molten steel is poured from the crucible in the melting chamber into the chute, and then flows into the ingot mold in the ingot mold chamber. The height from the chute outlet to the bottom of the ingot mold reaches 6 meters during pouring. The powerful impact can cause the shims at the bottom of the ingot mold to shift or crack. Since the density of molten steel is much higher than that of the refractory material, the shifted or damaged shims can easily cause them to float, severely affecting the final ingot product. The problem with the refractory ingot mold shims used in the vacuum induction furnace casting method is that the misalignment of the ingot mold shims causes the bottom of the steel ingot to tilt. Summary of the Invention

[0003] The technical problem to be solved by the present invention is: how to solve the problem of the gasket being easily misaligned as mentioned in the background art.

[0004] The technical solution adopted in this invention is: a method for controlling the bottom forming of steel ingots using a vacuum induction furnace top-pouring method, which is carried out according to the following steps: Step 1: Preparation before pouring. Prepare the upper and lower split double-opening ingot mold, shims and fixing rod device. The upper half of the upper and lower split double-opening ingot mold is covered on the lower half of the ingot mold and then fixed by tightening the ingot mold bolts. The shims are composed of an integrated structure of a disc and a frustum, wherein the maximum diameter of the frustum is equal to the diameter of the disc. Step 2: Install the shim. Use the overhead crane to slowly move the upper half of the mold away. Place the shim vertically inside the lower half of the mold, with the smaller end facing the bottom of the mold and tightly against the bottom of the mold. Use the fixing rod device to fix the shim. The maximum diameter of the shim should be 0-2mm away from the side wall of the lower half of the mold. Step 3: Ingot mold assembly. Use the overhead crane to slowly place the upper half of the ingot mold onto the lower half of the ingot mold. The head of the fixing rod device extends out from the pouring port to ensure that the upper half of the ingot mold and the lower half of the ingot mold are aligned and fit together tightly. After confirming that the position is appropriate, tighten the ingot mold bolts by diagonally driving bolts. Step 3: After the ingot mold is assembled, measure and check the position of the shim to confirm that the current shim position is consistent with the position before assembly. If there is any deviation, use the fixed ejector pin device to adjust it. If the adjustment cannot ensure that the current shim position is consistent with the position before assembly, return to step 2.

[0005] The gasket is a refractory ingot mold gasket, wherein the sum of the masses of Al2O2 and SiO2 accounts for more than or equal to 93% of the total mass of the gasket, and the mass of Al2O2 accounts for more than or equal to 65% of the total mass of the gasket, while the mass of SiO2 accounts for less than or equal to 28% of the total mass of the gasket, and the gasket density is greater than or equal to 2.3 g / cm³. 2 Its fire resistance is greater than or equal to 1700°.

[0006] The fixed top rod device includes multiple rods that are movably connected to the frustum surface, and all the rods are connected together to form a cone-shaped cage.

[0007] The beneficial effects of this invention are: it solves the problem of bottom tilting of steel ingots in the vacuum induction furnace casting method, while protecting the ingot mold from erosion, increasing the service life of the ingot mold, and reducing production costs. The bottom forming of the steel ingots produced by this method can meet the requirements for first-pass inspection, reducing the waste of precious metal elements, lowering production costs, effectively controlling the amount of inclusions carried into the steel ingot, and reducing the burden on subsequent finishing and electroslag treatment processes, thus meeting production needs. Attached Figure Description

[0008] Figure 1 This is a schematic front view of the gasket structure (without the push rod device) according to an embodiment of the present invention; Figure 2 This is a top view of the gasket structure according to an embodiment of the present invention; Figure 3 This is a top view schematic diagram of a gasket structure with a fixed top rod device according to an embodiment of the present invention; Figure 4 This is a schematic front view of a gasket structure with a fixed top rod device according to an embodiment of the present invention; Among them, 1. rod, 2. upper connecting device, 3. lower connecting device, 4. gasket. Detailed Implementation

[0009] The 6T vacuum induction furnace in Taiyuan Iron & Steel Group (TISCO) uses a split, double-opening ingot mold and employs a top-pouring method for casting steel ingots. During steel pouring, the height from the chute outlet to the bottom of the ingot mold reaches 6 meters. The powerful impact can cause the position of the shims at the bottom of the ingot mold to shift, and can also crack the refractory shims. Since the density of molten steel is much higher than that of refractory materials, the shifting or broken shims can easily cause them to float, seriously affecting the finished steel ingot.

[0010] This invention improves upon existing methods, as detailed below: A method for controlling the bottom forming of steel ingots using a vacuum induction furnace top-pouring method comprises the following steps: Step 1: Preparation before casting. Prepare the upper and lower split double-opening ingot mold, shims and fixing rod device. The ingot mold is a special mold used in the metallurgical industry to pour molten metal and solidify it into an ingot. Its core function is to achieve the forming of metal materials through a specific container structure.

[0011] The upper half of the split double-opening ingot mold is covered by the lower half of the ingot mold and then fixed by the ingot mold bolts. The top of the upper half of the ingot mold has a pouring port.

[0012] The gasket is an integral structure (or it can be a welded connection, bolted connection or other fixed connection) consisting of a disc and a frustum, wherein the diameter of the largest part of the frustum is equal to the diameter of the disc.

[0013] The lower half of the mold cavity used in this invention is cylindrical. It should be noted that the structure of the gasket should be adapted to the bottom of the lower half of the mold. For the lower half of the mold with a non-circular cross-section, such as a regular polygon, the corresponding gasket should be an integral structure (or a welded connection, bolted connection, or other fixed connection) of a regular polyprism and a regular polytrux. The bottom surface of the regular polyprism coincides with the top surface of the regular polytrux, and the area of ​​the top surface of the regular polytrux is larger than the area of ​​the bottom surface.

[0014] The gasket is a refractory ingot mold gasket, wherein the sum of the masses of Al2O2 and SiO2 accounts for more than or equal to 93% of the total mass of the gasket, and the mass of Al2O2 accounts for more than or equal to 65% of the total mass of the gasket, while the mass of SiO2 accounts for less than or equal to 28% of the total mass of the gasket, and the gasket density is greater than or equal to 2.3 g / cm³. 2 Its fire resistance is greater than or equal to 1700°.

[0015] The fixed top rod device includes multiple rods that are movably connected to the frustum surface, and all the rods are connected together to form a cone-shaped cage.

[0016] Step 2: Install the shim. Use the overhead crane to slowly move the upper part of the mold away. Place the shim vertically inside the lower part of the mold, with the smaller end facing the bottom of the mold and tightly against the bottom of the mold. Use the fixing rod device to fix the shim. The maximum diameter of the shim should be 0-2mm away from the side wall (inside) of the lower part of the mold.

[0017] The purpose of the gasket is to absorb the impact of the molten liquid and prevent damage to the bottom of the ingot mold. In this invention, the distance between the maximum cross-sectional area of ​​the gasket, i.e. the top area, and the inner wall of the ingot mold at that location is required to be less than 2 mm, thereby restricting the molten liquid from flowing into the lower part of the gasket through the gasket.

[0018] Step 3: Assemble the ingot mold. Use an overhead crane to slowly place the upper half of the ingot mold onto the lower half. The head of the fixing rod device extends out from the pouring port to ensure that the upper half and the lower half of the ingot mold are aligned and fit together tightly. After confirming that the position is appropriate, tighten the ingot mold bolts by diagonally driving bolts.

[0019] Step 3: After the ingot mold is assembled, measure and check the position of the shim to confirm that the current shim position is consistent with the position before assembly. If there is any deviation, use the fixed ejector pin device to adjust it. If the adjustment cannot ensure that the current shim position is consistent with the position before assembly, return to step 2.

[0020] The fixed top rod device includes multiple rods that are movably connected to the frustum surface, and all the rods are connected together to form a cone-shaped cage.

[0021] In one embodiment, such as Figure 1-4 As shown, rod 1 is a long bar with a cross-section that is one of a circle, a regular polygon, or a quadrilateral. The upper connecting device 2 is a ring that is movably connected to the upper part of each rod 1. The connection method can be bolted, snap-fit, etc., and this connection method adopts existing technology. The upper connecting device 2 extends from the pouring gate. The lower connecting device 3 connects rod 1 to the upper surface of the gasket. For example, if the gasket has a protruding, inclined stud, and the bottom end of rod 1 has a corresponding threaded countersunk hole, the connection can be achieved.

[0022] After removing the fixing rod device, the shim 4 is as follows Figure 1 and 2 As shown.

Claims

1. A method for controlling the bottom forming of steel ingots in a vacuum induction furnace top-pouring method, characterized in that, Follow these steps: Step 1: Preparation before pouring. Prepare the upper and lower split double-opening ingot mold, shims and fixing rod device. The upper half of the upper and lower split double-opening ingot mold is covered on the lower half of the ingot mold and then fixed by tightening the ingot mold bolts. The shims are composed of an integrated structure of a disc and a frustum, wherein the maximum diameter of the frustum is equal to the diameter of the disc. Step 2: Install the shim. Use the overhead crane to slowly move the upper half of the mold away. Place the shim vertically inside the lower half of the mold, with the smaller end facing the bottom of the mold and tightly against the bottom of the mold. Use the fixing rod device to fix the shim. The maximum diameter of the shim should be 0-2mm away from the side wall of the lower half of the mold. Step 3: Ingot mold assembly. Use the overhead crane to slowly place the upper half of the ingot mold onto the lower half of the ingot mold. The head of the fixing rod device extends out from the pouring port to ensure that the upper half of the ingot mold and the lower half of the ingot mold are aligned and fit together tightly. After confirming that the position is appropriate, tighten the ingot mold bolts by diagonally driving bolts. Step 3: After the ingot mold is assembled, measure and check the position of the shim to confirm that the current shim position is consistent with the position before assembly. If there is any deviation, use the fixed ejector pin device to adjust it. If the adjustment cannot ensure that the current shim position is consistent with the position before assembly, return to step 2.

2. The method for controlling the bottom forming of steel ingots using a vacuum induction furnace top-pouring method according to claim 1, characterized in that: The gasket is a refractory ingot mold gasket, wherein the sum of the masses of Al2O2 and SiO2 accounts for more than or equal to 93% of the total mass of the gasket, and the mass of Al2O2 accounts for more than or equal to 65% of the total mass of the gasket, while the mass of SiO2 accounts for less than or equal to 28% of the total mass of the gasket, and the gasket density is greater than or equal to 2.3 g / cm³. 2 Its fire resistance is greater than or equal to 1700°.

3. A method for controlling the bottom forming of steel ingots using a vacuum induction furnace top-pouring method according to claim 1, characterized in that: The fixed top rod device includes multiple rods that are movably connected to the frustum surface, and all the rods are connected together to form a cone-shaped cage.

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