A method for preventing the collapse of the working layer of a tundish

Abstract

The application provides a manufacturing method for preventing collapse of a working layer of a tundish, and relates to the technical field of steelmaking and continuous casting, and comprises the following steps: step one: measuring the temperature of a permanent layer of the tundish by using a temperature gun before working layer construction, and starting the construction when the temperature of the permanent layer is lower than 100 DEG C; step two: adding glass fibers to dry material, and performing dry material construction, and turning off the fire when the discoloration thickness of the dry material reaches 1 / 3 of the total thickness during low-temperature baking; the application turns off the fire when the discoloration thickness of the dry material reaches 1 / 3 of the total thickness during low-temperature baking, avoids separation of the working layer from the tundish due to too long baking time, controls low-temperature baking, medium-temperature baking and high-temperature baking time, optimizes the baking curve, adapts to the decomposition characteristics of phenolic resin and the low-temperature strength of the dry material, improves the bonding strength between the working layer and the permanent layer, improves the sintering strength of the working layer, avoids the generation of a carbonized layer close to the permanent layer, and thus avoids collapse of the working layer during baking.

Description

Technical Field

[0001] This invention relates to the field of steelmaking continuous casting technology, and in particular to a method for preventing material collapse in the working layer of the tundish. Background Technology

[0002] The intermediate ladle working layer, which is prepared for steel pouring after baking, usually only forms an oxidized and decarburized layer on the heated side, which is very weak, while the back side is a very strong carburized layer.

[0003] In the fragment of the collapsed burr, the fragment is divided into three layers: a carbonized layer is sandwiched in the middle, and a decarburized layer has also formed on the back side due to oxidation. The main reason for the presence of two decarburized layers is:

[0004] 1) The dry-mixed material has poor construction performance, or the new permanent layer is poorly bonded to the permanent layer during the baking process, resulting in blistering after proper binding.

[0005] 2) On-site construction skills were inadequate;

[0006] 3) Tight turnover of intermediate tundishes leads to hot tundish construction (permanent layer temperature exceeds 100 degrees Celsius);

[0007] 4) Uneven burner placement or prolonged baking time caused some areas of the working layer to harden completely;

[0008] These factors can cause the working layer to separate from the drum, forming the aforementioned sandwich layer during online baking, which in turn leads to the collapse of the tundish. Therefore, this invention proposes a manufacturing method to prevent the working layer of the tundish from collapsing in order to solve the problems existing in the prior art. Summary of the Invention

[0009] To address the aforementioned problems, this invention proposes a method for preventing the collapse of the intermediate ladle working layer. This method optimizes and improves the knotting method, demolding, and baking of the intermediate ladle working layer, effectively preventing the separation and collapse of the working layer from the permanent layer during the baking of the intermediate ladle.

[0010] To achieve the objective of this invention, the invention is implemented through the following technical solution: a method for preventing material collapse in the working layer of an intermediate ladle, comprising the following steps:

[0011] Step 1: Before constructing the working layer, use a temperature gun to measure the temperature of the permanent layer of the intermediate tundish. Construction begins when the temperature of the permanent layer is below 100 degrees Celsius.

[0012] Step 2: Add glass fiber to the dry material and carry out dry material construction. When baking at low temperature, turn off the heat when the color change thickness of the dry material reaches 1 / 3 of the total thickness.

[0013] Step 3: When demolding, use an overhead crane to lift the mold and place it in the designated position to prevent damage to the dry material liner and the resulting cracks;

[0014] Step 4: When baking, control the baking time at low temperature for 1-2 hours, the baking time at medium temperature for less than 30 minutes, and the baking time at high temperature for 40-50 minutes.

[0015] Step 5: When designing the new permanent layer membrane and working layer membrane, increase the inclination by 10-20% for areas prone to collapse;

[0016] Step 6: When processing the new permanent layer, groove the surface of the new permanent layer to create a rough texture.

[0017] A further improvement is that, in step one, when the temperature of the permanent layer is higher than 100 degrees Celsius, construction should only begin after the temperature of the permanent layer has naturally cooled to below 100 degrees Celsius.

[0018] Further improvements are made in the following steps: In step two, the specific process for dry material construction is as follows: First, install the sprue seat bricks of the intermediate ladle, ensuring that their upper surfaces are on the same plane. Then, pour the dry material evenly into the bottom of the ladle and tamp it firmly around the sprue seat bricks. Use a plate vibrator to compact the material at the bottom of the ladle. After the bottom of the ladle is completed, place the mold into the intermediate ladle. When placing the mold, control the gap thickness between the two sides of the mold and the permanent layer to be the same. Pour the dry material evenly along different positions on the side wall. Use a vibrator to drag around the mold to allow the dry material to fully vent air. Construct layer by layer until the dry material fills the entire gap and the height of the dry material is higher than the height of the permanent layer. Start the vibration motor in the mold to vibrate. Add dry material to fill the gaps left by the vibration and fully compact the top dry material. Then, perform low-temperature baking.

[0019] A further improvement is made in step two, where, during the low-temperature baking at 200-300 degrees Celsius, the heat is turned off when the dry material has changed color to 1 / 3 of its total thickness, to prevent the working layer from separating from the drum due to excessive baking time.

[0020] A further improvement is made in step three, where the force is controlled to be uniform during demolding, so as to prevent the dry material liner from being damaged and cracked, and to prevent damage to the working liner edge.

[0021] Further improvements are made in step four, where the purpose of controlling the baking time is to extend the low-temperature baking time, quickly bypass the medium-temperature baking stage, enable the dry material working layer to reach the sintering state, and reduce the high-temperature baking time, thereby adapting to the decomposition characteristics of phenolic resin and the low medium-temperature strength of dry material.

[0022] A further improvement is made in step four, where the temperature is controlled at 200-300 degrees Celsius during low-temperature baking, 800-900 degrees Celsius during medium-temperature baking, and 1100-1200 degrees Celsius during high-temperature baking.

[0023] A further improvement is made in step five by increasing the inclination angle, which is suitable for intermediate tundishes with small inclination angles, thin working layer thickness, deep, narrow and long shells.

[0024] A further improvement is made in step six, where the grooved surface is roughened to reduce the smoothness of the permanent layer and increase friction and adhesion performance.

[0025] The beneficial effects of this invention are as follows:

[0026] 1. In this invention, the heat is turned off when the dry material reaches 1 / 3 of the total thickness during low-temperature baking to avoid the working layer from separating from the drum due to excessive baking time. The invention also controls the baking time for low-temperature baking, medium-temperature baking, and high-temperature baking, optimizes the baking curve, adapts to the decomposition characteristics of phenolic resin and the low strength of dry material at medium temperature, improves the bonding strength between the working layer and the permanent layer, improves the sintering strength of the working layer, and avoids the formation of a carbonized layer on the side near the permanent layer, thereby preventing the working layer from collapsing during baking.

[0027] 2. The present invention grooves the new permanent layer of the intermediate liner to increase the adhesion between the working layer and the permanent layer.

[0028] 3. This invention introduces glass fiber into dry-mixed materials to enhance their toughness, prevent or delay the development of microcracks, reduce the rate of strength reduction, and effectively improve the resistance of dry-mixed materials to collapse and spalling.

[0029] 4. In designing the permanent layer and working layer molds, this invention increases the inclination of parts prone to collapse, which can effectively reduce the collapse phenomenon in the actual use of dry materials. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the slotted and inclined surface of the new permanent layer in the intermediate package of the present invention. Detailed Implementation

[0031] To enhance understanding of the present invention, the present invention will be further described in detail below with reference to embodiments. These embodiments are only used to explain the present invention and do not constitute a limitation on the scope of protection of the present invention.

[0032] Example 1

[0033] according to Figure 1 As shown in the figure, this embodiment proposes a method for preventing material collapse in the working layer of the tundish, including the following steps:

[0034] Step 1: Before constructing the working layer, use a temperature gun to measure the temperature of the permanent layer of the intermediate tundish. Construction begins when the temperature of the permanent layer is below 100 degrees Celsius.

[0035] Step 2: Add glass fiber to the dry material and carry out dry material construction. When baking at low temperature, turn off the heat when the color change thickness of the dry material reaches 1 / 3 of the total thickness.

[0036] Step 3: When demolding, use an overhead crane to lift the mold and place it in the designated position to prevent damage to the dry material liner and the resulting cracks;

[0037] Step 4: When baking, control the baking time at low temperature for 1-2 hours, the baking time at medium temperature for less than 30 minutes, and the baking time at high temperature for 40-50 minutes.

[0038] Step 5: When designing the new permanent layer membrane and working layer membrane, increase the inclination by 10-20% for areas prone to collapse;

[0039] Step 6: When processing the new permanent layer, groove the surface of the new permanent layer to create a rough texture.

[0040] This invention shuts off the heat when the dry material reaches 1 / 3 of its total thickness during low-temperature baking, avoiding excessive baking time that could cause the working layer to detach from the drum. It also controls the baking time for low-temperature, medium-temperature, and high-temperature baking, optimizes the baking curve, and adapts to the decomposition characteristics of phenolic resin and the low strength of dry material at medium temperatures. This improves the bonding strength between the working layer and the permanent layer, increases the sintering strength of the working layer, and avoids the formation of a carbonized layer near the permanent layer, thereby preventing the working layer from collapsing during baking.

[0041] Example 2

[0042] according to Figure 1 As shown in the figure, this embodiment proposes a method for preventing material collapse in the working layer of the tundish, including the following steps:

[0043] Before constructing the working layer, use a temperature gun to measure the temperature of the permanent layer of the intermediate tundish. When the temperature of the permanent layer is below 100 degrees Celsius, construction should begin (the softening point of phenolic resin is 103-106 degrees Celsius). When the temperature of the permanent layer is above 100 degrees Celsius, wait for the working layer temperature to cool naturally to below 100 degrees Celsius before starting construction.

[0044] Adding glass fiber to the dry-mix material and then applying it during dry-mix construction is as follows: First, install the sprue seat bricks in the intermediate tundish, ensuring their upper surfaces are on the same plane. Then, pour the dry-mix material evenly into the bottom of the tundish and tamp it firmly around the sprue seat bricks. Use a flat vibrator to compact the bottom material. After the bottom construction is complete, place the mold into the intermediate tundish. When placing the mold, control the gap thickness between the mold sides and the permanent layer to be the same. Pour the dry-mix material evenly along different positions on the side walls. Use a vibrator to drag around the mold to fully vent the dry-mix material. Apply the material layer by layer until it fills the entire gap and the height of the dry-mix material is higher than the height of the permanent layer. Start the vibrating motor inside the mold to vibrate it. Add more dry-mix material to fill the gaps left by the vibration and fully compact the top dry-mix material. Then, perform low-temperature baking. When baking at a low temperature of 200-300 degrees Celsius, turn off the heat when the dry-mix material changes color and reaches 1 / 3 of the total thickness to prevent the working layer from separating from the drum due to excessive baking time.

[0045] Introducing an appropriate amount of alkali-free glass fiber achieves the following three effects through glass fiber reinforcement: even with rapid baking at high temperatures in the tundish (baking time reduced by 1 / 3), the collapse of the dry material is avoided; even with prolonged baking at 300℃ in a mold, the dry material layer and the permanent layer do not separate; the glass fiber in the surface layer of the dry material melts at high temperatures and acts as a sintering agent, allowing for the addition of less or no medium-temperature sintering agent; the addition of fiber material to the brittle dry material layer allows the fiber to bear part of the internal stress of the material, preventing or delaying the development of microcracks; before the material layer fails, the tensile force it experiences is shared by the fiber and the material layer; after the material layer cracks, the stress is transferred from the material layer to the adjacent fibers.

[0046] When demolding, use an overhead crane to lift the mold and place it in the designated position to prevent damage to the dry material liner and cracks. When pulling up the demolding, control the force evenly to prevent damage to the dry material liner and cracks, and also to prevent damage to the working liner edge.

[0047] During baking, the low-temperature baking time should be controlled at 1-2 hours, the medium-temperature baking time at less than 30 minutes, and the high-temperature baking time at 40-50 minutes. The purpose of controlling the baking time is to appropriately extend the low-temperature baking time, quickly bypass the medium-temperature baking stage, and allow the dry material working layer to reach the sintering state as soon as possible, while reducing the need for rapid high-temperature baking. This adapts to the decomposition characteristics of phenolic resin and the low strength of dry material at medium temperatures. During low-temperature baking, the temperature should be controlled at 200-300 degrees Celsius; during medium-temperature baking, the temperature should be controlled at 800-900 degrees Celsius; and during high-temperature baking, the temperature should be controlled at 1100-1200 degrees Celsius.

[0048] When designing the new permanent layer mold and working layer mold, increase the inclination by 10-20% for areas prone to collapse. This is especially beneficial for tundishes with small inclination of the tundish shell, thin working layer, and deep, narrow, and long shell. If the inclination is appropriately increased during the casting of the permanent layer, taking into account the working layer and lowering its center of gravity, the probability of dry material collapse will be greatly reduced. Alternatively, increasing the inclination when designing the tundish dry material mold can also reduce the probability of collapse. This is particularly important for large-volume, high-tonnage tundishes with significant height. Considering this issue in advance when designing the permanent layer mold and working layer mold, and appropriately increasing the inclination for areas prone to collapse, such as opposite the impact zone, helps to suppress material layer collapse caused by rapid heating and fluctuations in the quality of the dry material.

[0049] When processing the new permanent layer, the surface of the new permanent layer is grooved to form a rough surface. Grooving to form a rough surface is used to reduce the smoothness of the permanent layer and increase friction and adhesion performance. Since the surface of the new permanent layer is smooth and not easy for dry materials to adhere, grooving to form a rough surface helps to reduce the risk of dry material collapse.

[0050] This method for preventing the collapse of the intermediate ladle working layer involves shutting off the heat during low-temperature baking when the dry material's color change thickness reaches 1 / 3 of the total thickness. This avoids excessive baking time that could cause the working layer to detach from the drum. The method also controls the baking times for low-temperature, medium-temperature, and high-temperature baking, optimizing the baking curve to suit the decomposition characteristics of phenolic resin and the low medium-temperature strength of the dry material. This improves the bonding strength between the working layer and the permanent layer, enhances the sintering strength of the working layer, and prevents the formation of a carbonized layer near the permanent layer, thus preventing the working layer from collapsing during baking. Furthermore, this invention grooves the new permanent layer of the intermediate ladle to increase the adhesion between the working layer and the permanent layer. Simultaneously, this invention introduces glass fiber into the dry material to enhance its toughness, prevent or delay the development of microcracks, reduce the rate of strength reduction, and effectively improve the dry material's resistance to collapse and peeling. Additionally, this invention increases the inclination of areas prone to collapse when designing the molds for the permanent and working layers, effectively reducing collapse phenomena in actual use of the dry material.

[0051] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preventing material collapse in the working layer of an intermediate ladle, characterized in that, Includes the following steps: Step 1: Before constructing the working layer, use a temperature gun to measure the temperature of the permanent layer of the intermediate tundish. Construction begins when the temperature of the permanent layer is below 100 degrees Celsius. Step 2: Add glass fiber to the dry material and carry out dry material construction. When baking at a low temperature of 200-300 degrees Celsius, turn off the heat when the dry material changes color and the thickness reaches 1 / 3 of the total thickness to prevent the working layer from separating from the drum due to excessive baking time. Step 3: When demolding, use an overhead crane to lift the mold and place it in the designated position to prevent damage to the dry material liner and the resulting cracks; Step 4: During baking, control the baking time at low temperature for 1-2 hours, the baking time at medium temperature for less than 30 minutes, and the baking time at high temperature for 40-50 minutes. When baking at low temperature, control the temperature at 200-300 degrees Celsius; when baking at medium temperature, control the temperature at 800-900 degrees Celsius; and when baking at high temperature, control the temperature at 1100-1200 degrees Celsius. Step 5: When designing the new permanent layer membrane and working layer membrane, increase the inclination by 10-20% for areas prone to collapse; Step 6: When processing the new permanent layer, groove the surface of the new permanent layer to create a rough texture.

2. The method for preventing material collapse in the working layer of the tundish according to claim 1, characterized in that: In step one, when the temperature of the permanent layer is higher than 100 degrees Celsius, construction should only begin after the temperature of the permanent layer has naturally cooled to below 100 degrees Celsius.

3. The method for preventing material collapse in the intermediate ladle working layer according to claim 2, characterized in that: In step two, the specific process of dry material construction is as follows: First, install the sprue seat bricks of the intermediate ladle, ensuring that their upper surfaces are on the same plane. Then, pour dry material evenly into the bottom of the ladle and tamp it tightly around the sprue seat bricks. Use a plate vibrator to compact the material at the bottom of the ladle. After the bottom of the ladle is completed, place the mold into the intermediate ladle. When placing the mold, control the gap thickness between the two sides of the mold and the permanent layer to be the same. Pour dry material evenly along different positions on the side wall. Use a vibrator to drag around the mold to allow the dry material to fully vent air. Construct layer by layer until the dry material fills the entire gap and the height of the dry material is higher than the height of the permanent layer. Start the vibration motor in the mold to vibrate. Add dry material to fill the gaps left by the vibration and fully compact the top dry material. Then, perform low-temperature baking.

4. The method for preventing material collapse in the intermediate ladle working layer according to claim 3, characterized in that: In step three, when pulling up the demolding, the force should be controlled to be uniform, so as to prevent the dry material liner from being damaged and cracked, and to prevent the working liner edge from being damaged.

5. A method for preventing material collapse in the intermediate ladle working layer according to claim 4, characterized in that: In step four, the purpose of controlling the baking time is to extend the low-temperature baking time, quickly pass through the medium-temperature baking stage, enable the dry material working layer to reach the sintering state, and reduce the high-temperature baking time, thereby adapting to the decomposition characteristics of phenolic resin and the low medium-temperature strength of dry material.

6. A method for preventing material collapse in the intermediate ladle working layer according to claim 5, characterized in that: In step five, the inclination is increased to target intermediate tundishes with small inclination of the intermediate shell, thin working layer thickness, and deep, narrow and long shell.

7. A method for preventing material collapse in the working layer of an intermediate ladle according to claim 6, characterized in that: In step six, the grooving process creates a rough surface, which reduces the smoothness of the permanent layer and increases friction and adhesion performance.

Images