Tundish submerged entry nozzle

Abstract

The utility model discloses a tundish immersion type nozzle belongs to metallurgical technical field, has solved the one of the problem of the nozzle inner wall inclusion attachment probability big, immersion type nozzle nodulation probability big, steel liquid quality is poor in the use process of existing immersion type nozzle. The tundish immersion type nozzle of the utility model includes the nozzle body, the outer wall of nozzle body is smooth, the inner wall of nozzle body is the internal thread of reverse spiral or positive spiral, when being used for the equipment of northern hemisphere, the inner wall is the internal thread of reverse spiral, when being used for the equipment of southern hemisphere, the inner wall is the internal thread of positive spiral. The tundish immersion type nozzle of the utility model is helpful to optimize the steel liquid quality, reduces oxygen content and optimizes inclusion quantity, can slow down the nodulation of tundish immersion type nozzle, reaches the purpose of improving continuous casting furnace time.

Description

Technical Field

[0001] This utility model belongs to the field of metallurgical technology, and specifically relates to an immersion nozzle for an intermediate ladle. Background Technology

[0002] In continuous casting technology, in order to improve the quality of the billet, an immersion nozzle is installed between the tundish and the crystallizer. Its main functions are: (1) to prevent secondary oxidation and nitriding of molten steel and to prevent splashing of molten steel; (2) to regulate the flow state and injection speed of molten steel; (3) to prevent non-metallic inclusions in the protective slag from being drawn into the molten steel, and to play an important role in promoting the flotation of inclusions in the molten steel; (4) to have a decisive influence on the yield of side casting and the quality of the billet.

[0003] Submerged entry nozzles are installed at the bottom of the tundish and inserted into the crystallizer. Existing submerged entry nozzles are generally cylindrical with smooth inner and outer walls. During use, there is a high probability of inclusions adhering to the inner wall of the nozzle, resulting in a high probability of nodule formation and affecting the quality of the molten steel. Utility Model Content

[0004] Based on the above analysis, this utility model aims to provide a tundish immersion nozzle. By optimizing the structure of the tundish immersion nozzle, at least one of the following technical problems can be solved: existing immersion nozzles have a high probability of inclusions adhering to the inner wall of the nozzle during use, a high probability of nodule formation, poor steel quality, short service life, and high cost.

[0005] The objective of this utility model is mainly achieved through the following technical solutions:

[0006] This utility model provides an immersion nozzle for tundishes. The immersion nozzle includes a nozzle body with a smooth outer wall and an inner wall with a reverse or forward spiral internal thread. When used in equipment in the Northern Hemisphere, the inner wall has a reverse spiral internal thread, and when used in equipment in the Southern Hemisphere, the inner wall has a forward spiral internal thread.

[0007] Furthermore, the inner diameter D of the internal thread of the tundish immersion nozzle. 螺纹内径 The outer diameter D of the tundish submersible nozzle 外径 It conforms to the following relationship: D 外径 =D 螺纹内径 +2×thread height H+(2~6), D 外径 D 螺纹内径 All units are cm.

[0008] Furthermore, the parameters of positive spiral internal threads and negative spiral internal threads are the same.

[0009] Furthermore, the thread pitch h of the internal thread is related to the thread inner diameter D. 螺纹内径 It conforms to the following relationship: 0.02×D螺纹内径 ≤h≤0.2×D 螺纹内径 .

[0010] Furthermore, the thread pitch h of the internal thread is (1~10) × thread height H.

[0011] Furthermore, the internal threads are evenly spaced.

[0012] Furthermore, the cross-section of the internal thread is a smooth parabolic shape.

[0013] Furthermore, the tundish immersion nozzle body has a molten steel outlet on its side wall.

[0014] Furthermore, the thread height H is 0.3 to 1 cm.

[0015] Furthermore, the thread pitch h is 1 to 10 cm.

[0016] Compared with the prior art, the present invention can achieve at least one of the following technical effects:

[0017] The inner wall of the tundish submersible nozzle of this invention features a reverse or forward spiral internal thread. When used in equipment in the Northern Hemisphere, the inner wall has a reverse spiral internal thread. After the molten steel flows into the tundish submersible nozzle from the upper part of the tundish, it rotates counterclockwise and flows downward, consistent with the spontaneous rotation direction of liquids due to the Earth's rotation. When used in equipment in the Southern Hemisphere, the inner wall has a forward spiral internal thread. After the molten steel flows into the tundish submersible nozzle from the upper part of the tundish, it rotates clockwise and flows downward, consistent with the spontaneous rotation direction of liquids due to the Earth's rotation. Using an internal thread consistent with the downward spiral direction of liquids in the Northern or Southern Hemisphere increases the flow velocity of the molten steel, enhances the centrifugal rotation speed of the molten steel as it flows through the thread due to gravity, and reduces the probability of inclusions adhering to the inner wall of the nozzle.

[0018] This utility model's tundish immersion nozzle, by precisely controlling the relationship between the pitch and the thread height, can leave a certain space for inclusions to accumulate at the bottom of the thread, thus mitigating the filling and damage to the thread structure caused by the width and height of the nodules. On the other hand, by increasing the pitch and reducing the thread height, it can reduce the scouring of the thread structure by the molten steel, ensuring that the internal thread nozzle has a certain service life.

[0019] The tundish submerged entry nozzle of this invention can increase the flow rate of molten steel in the tundish submerged entry nozzle of continuous casting, reduce the probability of inclusions adhering to the inner wall of the nozzle, help optimize the quality of molten steel, reduce oxygen content and optimize the number of inclusions; it can also slow down the formation of nodules in the tundish submerged entry nozzle, thereby increasing the number of continuous casting furnaces, improving production efficiency and reducing production costs.

[0020] Other features and advantages of this invention will be set forth in the following description, and in part will be obvious from the description or may be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained by means of the structures particularly pointed out in the written description and the accompanying drawings. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the overall structure of the intermediate ladle immersion nozzle of this utility model.

[0022] Figure 2 This is a cross-sectional view of the intermediate ladle immersion nozzle of this utility model.

[0023] Figure label:

[0024] 1-Sprue body, 2-Internal thread, 3-Steel liquid outlet, 4-Support part. Detailed Implementation

[0025] The following detailed description of an intermediate ladle immersion nozzle is provided in conjunction with specific embodiments. These embodiments are for comparative and illustrative purposes only, and the present invention is not limited to these embodiments.

[0026] In the existing technology, the tundish immersion nozzle is generally a cylindrical shape with smooth inner and outer walls. During use, there is a high probability of inclusions adhering to the inner wall of the nozzle, and a high probability of nodule formation in the immersion nozzle, which affects the quality of the molten steel.

[0027] like Figure 1 As shown, this utility model provides an tundish immersion nozzle, which includes a nozzle body 1. The outer wall of the nozzle body 1 is smooth, and the inner wall of the nozzle body 1 is an internal thread 2 with a reverse spiral (i.e., when viewed from above, the thread rotates counterclockwise and extends downward) or a positive spiral (i.e., when viewed from above, the thread rotates clockwise and extends downward). When used in equipment in the Northern Hemisphere, the inner wall is a reverse spiral internal thread, and when used in equipment in the Southern Hemisphere, the inner wall is a positive spiral internal thread.

[0028] It should be noted that when the inner wall of the tundish submersible nozzle has a reverse spiral internal thread, after the molten steel flows into the tundish submersible nozzle from the upper tundish, the molten steel rotates counterclockwise and flows downwards, which is consistent with the spontaneous rotation direction of liquids in the Northern Hemisphere during the Earth's rotation. Therefore, it is used in equipment in the Northern Hemisphere.

[0029] It should be noted that when the inner wall of the tundish immersion nozzle is a positive spiral internal thread, after the molten steel flows into the tundish immersion nozzle from the upper tundish, the molten steel rotates clockwise and flows downwards, which is consistent with the spontaneous rotation direction of liquids in the Southern Hemisphere during the Earth's rotation. Therefore, it is used in equipment in the Southern Hemisphere.

[0030] Using an internal thread that aligns with the downward spin direction of the liquid in the Northern or Southern Hemisphere can increase the flow velocity of the molten steel, enhance the centrifugal rotation speed of the molten steel as it flows through the thread due to gravity, and reduce the likelihood of inclusions adhering to the inner wall of the nozzle.

[0031] Specifically, the tundish immersion nozzle body 1 is provided with a molten steel outlet 3 on its side wall for molten steel to flow out.

[0032] Specifically, the inner diameter D of the internal thread of the aforementioned tundish immersion nozzle... 螺纹内径 The outer diameter D of the tundish submersible nozzle 外径 It conforms to the following relationship: D 外径 =D 螺纹内径 +2×thread height H+(2~6), D 外径 D 螺纹内径 All units are cm.

[0033] Specifically, the inner diameter of the aforementioned internal thread is D. 螺纹内径 The outer diameter D of the intermediate sump submersible nozzle is 8-12cm. 外径 It is 10-17cm.

[0034] Specifically, the parameters of positive spiral internal threads and negative spiral internal threads are the same.

[0035] Specifically, considering that an excessively large thread pitch h would not accelerate the rotation of the molten steel, while an excessively small h would hinder the flow of molten steel within the thread, the thread pitch h and the thread inner diameter D must be controlled accordingly. 螺纹内径 It conforms to the following relationship: 0.02×D 螺纹内径 ≤h≤0.2×D 螺纹内径 .

[0036] Specifically, the thread pitch h of the aforementioned internal thread is (1~10) × thread height H. The main purpose of this design is twofold: firstly, to allow sufficient space for inclusions to accumulate at the bottom of the thread, thus mitigating the impact of nodule width and height on the thread structure; and secondly, to reduce the scouring effect of molten steel on the thread structure by increasing the thread pitch h and decreasing the thread height H, thereby ensuring a certain service life for the internal thread nozzle.

[0037] Specifically, the thread height H is 0.3 to 1 cm, for example, 0.3 cm, 0.4 cm, 0.5 cm, 0.6 cm, 0.7 cm, 0.8 cm, 0.9 cm, and 1.0 cm.

[0038] Specifically, the thread pitch h is 1 to 10 cm, preferably 1 to 5 cm, such as 1 cm, 2 cm, 3 cm, 4 cm, or 5 cm.

[0039] Specifically, the internal threads mentioned above are evenly spaced.

[0040] Specifically, the cross-section of the internal thread is a smooth parabolic shape, which helps to reduce the resistance to molten steel flow and slow down the erosion rate of the internal thread.

[0041] Specifically, the upper outer side of the sprue body 1 of the intermediate sprue immersion sprue is provided with an outwardly protruding support part 4 for easy installation.

[0042] Specifically, the material of the intermediate tundish immersion nozzle is Al2O3-C.

[0043] It should be noted that after molten steel flows from the tundish into the internally threaded submersible nozzle by gravity, the spiral structure of the internal thread causes the molten steel to rotate downwards, generating centrifugal force. This means that inclusions in the molten steel may be thrown from the top of the thread protrusions to the bottom of the thread recesses. As the molten steel continues to flow, inclusions tend to accumulate more at the bottom of the thread, effectively mitigating the risk of inclusions accumulating, growing, and forming nodules that could clog the inner diameter of the submersible nozzle. The spiral structure effectively reduces the problem of inclusions accumulating and growing at random locations, thus slowing down the time it takes for the submersible nozzle to become clogged by inclusion nodules. This increases the service life and throughput of the submersible nozzle, ultimately achieving the goals of increasing the number of continuous casting furnaces and reducing production costs.

[0044] The tundish immersion nozzle of this invention can reduce the probability or speed of nozzle clogging that often occurs in continuous casting, increase the number of consecutive casting cycles, and especially ensure the smooth operation of certain consecutive casting cycles for rare earth steel.

[0045] The preparation method of the intermediate ladle immersion nozzle of this utility model includes the following steps:

[0046] The material is made from general-purpose refractory materials, which are mixed evenly and then pressed using isostatic pressing. To improve the erosion resistance of the threads, the amount of resin binder is increased by 1% to 3% compared to traditional immersion nozzles, and the isostatic pressing pressure is ≥150MPa. After pressing, the material is dried and dehydrated at 200℃ to 800℃ for 2 to 8 hours under an argon protective atmosphere in an electric heating furnace. It is then cooled to room temperature in a drying and heat preservation pit or drying and heat preservation box. After shaping, processing, and flaw detection, the material is sealed in a plastic bag and placed in a dry cardboard box for later use.

[0047] The above-mentioned method of using the tundish immersion nozzle is as follows: Remove the tundish immersion nozzle from the packaging and heat it with gas at 800℃~1000℃ for 2~4 hours for continuous casting.

[0048] Example 1

[0049] This embodiment provides an immersion nozzle for a tundish. The outer wall of the immersion nozzle is smooth and is used in equipment in the Northern Hemisphere. The inner wall has a reverse spiral internal thread. The inner diameter of the internal thread is 10 cm and the outer diameter of the thread is 14 cm.

[0050] Specifically, the thread height H is 0.5cm.

[0051] Specifically, the thread pitch h is 2cm.

[0052] Specifically, the aforementioned internal threads are evenly spaced.

[0053] Specifically, the cross-section of the internal thread is a smooth parabolic shape.

[0054] The material of the intermediate tundish immersion nozzle in this embodiment is Al2O3-C.

[0055] The tundish submersible nozzle of this embodiment and the existing smooth-walled submersible nozzle are used for continuous casting of ordinary carbon steel 45# steel, 250mm*250mm square billet. The existing smooth-walled submersible nozzle is made of Al2O3-C material.

[0056] The effects of using the tundish submersible nozzle of this embodiment and the existing submersible nozzle with a smooth inner wall for continuous casting are shown in Table 1 below.

[0057] Table 1 Comparison of continuous casting effects

[0058]

[0059] Example 2

[0060] The tundish submerged entry nozzle of Example 1 and the existing submerged entry nozzle with smooth inner wall were used to continuously cast 250mm*250mm square billets of rare earth 10# steel (rare earth content of 20-30ppm). The results of the continuous casting are shown in Table 2 below.

[0061] Table 2 Comparison of continuous casting effects

[0062]

[0063]

[0064] It is evident that the tundish submerged entry nozzle of this invention can increase the flow rate of molten steel in the continuous casting tundish submerged entry nozzle, reduce the probability of inclusions adhering to the inner wall of the nozzle, help optimize the quality of molten steel, reduce oxygen content and optimize the number of inclusions; it can also slow down the formation of nodules in the tundish submerged entry nozzle, thereby increasing the number of continuous casting furnaces, improving production efficiency and reducing production costs.

[0065] The above description is only a preferred embodiment of the present utility model, but the protection scope of the present utility model is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present utility model should be included within the protection scope of the present utility model.

Claims

1. A submersible sprue for intermediate ladles, characterized in that, The intermediate tundish immersion nozzle includes a nozzle body (1), the outer wall of the nozzle body (1) is smooth, and the inner wall of the nozzle body (1) is a reverse spiral or a forward spiral internal thread (2). When used for equipment in the Northern Hemisphere, the inner wall is a reverse spiral internal thread, and when used for equipment in the Southern Hemisphere, the inner wall is a forward spiral internal thread. The inner diameter D of the internal thread (2) of the tundish immersion nozzle 螺纹内径 The outer diameter D of the tundish submersible nozzle 外径 It conforms to the following relationship: D 外径 =D 螺纹内径 +2×thread height H+2~6,D 外径 D 螺纹内径 The units are all cm; The thread pitch h of the internal thread (2) is related to the thread inner diameter D. 螺纹内径 It conforms to the following relationship: 0.02×D 螺纹内径 ≤h≤0.2×D 螺纹内径 ; The thread pitch h of the internal thread (2) is (1~10) × thread height H; The upper outer side of the sprue body of the intermediate tundish immersion sprue is provided with an outwardly protruding support. For continuous casting of ordinary carbon steel, an immersion nozzle was used in the tundish. The number of consecutive castings was 15. The blockage was less than 1 / 3 of the diameter, and the number of inclusions larger than 10μm was 3.78 per mm. 2 Rare earth steel was continuously cast in 5 furnaces, with 1.93 inclusions larger than 10μm per mm. 2 .

2. The tundish immersion nozzle according to claim 1, characterized in that, The parameters of the positive spiral internal thread and the negative spiral internal thread are the same.

3. The tundish immersion nozzle according to claim 1, characterized in that, The internal threads are evenly spaced.

4. The tundish immersion nozzle according to claim 1, characterized in that, The cross-section of the internal thread is a smooth parabolic shape.

5. The tundish immersion nozzle according to claim 1, characterized in that, The tundish immersion nozzle body (1) is provided with a molten steel outlet (3) on its side wall.

6. The intermediate ladle immersion nozzle according to any one of claims 1 to 5, characterized in that, The thread height H is 0.3~1cm.

7. The intermediate ladle immersion nozzle according to any one of claims 1 to 5, characterized in that, The thread pitch h is 1~10cm.

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