Sealing sleeve for the gap between the continuous casting dummy head and the mould and method for plugging it

Abstract

This invention discloses a sealing sleeve and its sealing method for the gap between the ingot head and the crystallizer in continuous casting, belonging to the technical field of continuous metal casting. The sealing sleeve is formed by pressing refractory material and is circumferentially spliced ​​from two or four sealing blocks with inverted tapers. The inner side of each sealing block has a positioning protrusion that mates with the groove of the ingot head. An elastic expansion ring with a V-shaped or U-shaped cross-section is integrally formed on the outer sealing surface. The radial protrusion height is not less than 1.2 times the maximum gap between the sealing sleeve and the crystallizer. The sealing blocks are joined by mortise and tenon joints, and the joints are coated with a high-temperature adhesive. During installation, each sealing block is sequentially inserted into the lower opening of the crystallizer and pressed together. The positioning protrusion engages with the groove of the ingot head, and the elastic expansion ring is compressed to form an initial interference seal. After casting begins, high-temperature sintering and solidification form a dense sealing layer. This invention completely replaces asbestos materials, requires no hammering during installation, does not damage the copper plate, adapts to gap manufacturing errors, reduces casting preparation time by more than 80%, and lowers the steel leakage rate.

Description

Technical Field

[0001] This application relates to the technical field of continuous metal casting, and in particular to a sealing sleeve for the gap between the continuous casting ingot head and the crystallizer, and a sealing method thereof. Background Technology

[0002] During the start-up phase of continuous casting production, the dummy bar needs to be inserted into the lower opening of the crystallizer to form the connection base between the dummy bar and the billet. To prevent the injected molten steel from leaking out of the gap between the dummy bar and the copper plate of the crystallizer, this gap must be sealed before casting begins. For a long time, asbestos rope or asbestos cloth has been commonly used for packing on site. However, asbestos is a Group 1 carcinogen and releases inhalable fibers during high-temperature operations, seriously threatening the health of operators. Moreover, asbestos packing relies entirely on manual experience and feel, making it difficult to standardize the packing force. This not only results in long preparation times but also significant fluctuations in the sealing effect.

[0003] To phase out asbestos, several sealing solutions using refractory fiber blocks have been developed. For example, Chinese patent document CN118122971A discloses a method for sealing dummy ingots produced by continuous casting of iron-nickel-based alloys, using integrally molded V-shaped fiber blocks to fill gaps; CN104226946A discloses a sealing method for the dummy ingot head of round billet continuous casting, also employing ceramic fiber sealants. These solutions require a copper hammer to drive the fiber blocks into the bottom of the crystallizer during installation. This hammering process easily causes the fiber blocks to crack and may damage the inner wall of the copper plate in the crystallizer, reducing its lifespan. More importantly, the integral sealing block cannot accommodate gap deviations between the dummy ingot head and the crystallizer caused by manufacturing tolerances and installation eccentricity. When the gap is uneven, the sealing reliability is severely insufficient.

[0004] Chinese patent document CN95203137.X discloses a segmented ingot head sealing block, which divides the sealing block into two or four pieces. The inner side has protrusions that engage with the grooves in the ingot head, and the outer side has grooves. The sealing block is secured to the ingot head by manually winding reinforcing wire. While this method avoids the poor adaptability of a single block to gaps, the winding process remains cumbersome, and the tightening force relies entirely on the operator's experience, making it difficult to guarantee circumferential uniformity. Furthermore, the sealing blocks in this design are simply spliced ​​together, with no special sealing treatment at the joints. At high temperatures, molten steel can easily seep through the joints, creating a potential for steel leakage.

[0005] Therefore, there is still an urgent need in the industry for a spindle sealing device that can be installed without damaging the crystallizer, is not sensitive to gap tolerances, can reliably seal the joints, and can completely replace asbestos. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a sealing sleeve and sealing method for the gap between the continuous casting dummy head and the crystallizer. It can completely avoid the knocking operation during installation, adapt to the manufacturing error of the gap between the dummy head and the crystallizer, and establish a reliable seal for the whole, including the joint, in both the room temperature installation and high temperature sintering stages.

[0007] To solve the above problems, the present invention adopts the following technical solution:

[0008] On the one hand, the present invention provides a sealing sleeve for the gap between the continuous casting ingot head and the crystallizer. The sealing sleeve is pre-pressed from refractory material and is formed by splicing two or four sealing blocks with inverted taper along the circumference to form a complete ring.

[0009] The inner side of the sealing block is provided with a positioning protrusion, which is used to engage with the circumferential groove on the outer wall of the spindle head to limit the axial and radial displacement of the sealing sleeve.

[0010] The outer side of the sealing block is a sealing surface opposite to the inner wall of the crystallizer. At least one elastic expansion ring is integrally formed circumferentially on this sealing surface. The cross-section of the elastic expansion ring is V-shaped or U-shaped. In the free state, the radial protrusion height of the elastic expansion ring relative to the sealing surface is not less than 1.2 times the maximum design gap between the sealing sleeve and the crystallizer.

[0011] The mating surfaces of adjacent sealing blocks are respectively provided with tenons and mortises that can mesh with each other, forming a mortise and tenon structure. The mating surfaces of the tenons and mortises, as well as the joint between them, are coated with an inorganic high-temperature adhesive for high-temperature sintering and curing.

[0012] On the other hand, the present invention also provides a method for sealing continuous casting ingots using the above-mentioned sealing sleeve, comprising the following steps:

[0013] (a) Select the appropriate sealing sleeve based on the cross-sectional dimensions of the crystallizer cavity and the outer diameter of the ingot head;

[0014] (b) Send each sealing block into the lower opening of the crystallizer in sequence, and splice them into a complete rectangular or circular sealing sleeve through the mortise and tenon structure.

[0015] (c) Press down on the assembled sealing sleeve so that the positioning protrusion on its inner side engages with the groove on the outer wall of the ingot head. At the same time, the elastic expansion ring on the outer side of the sealing sleeve is subjected to radial compression by the inner wall of the crystallizer, resulting in elastic deformation, thereby forming an initial interference seal between the sealing sleeve and the inner wall of the crystallizer;

[0016] (d) After pouring, the high temperature of the molten steel causes the high-temperature adhesive at the sealing sleeve and joint to sinter and solidify, forming an integral and dense sealing layer.

[0017] Compared with the prior art, the present invention brings the following beneficial effects:

[0018] First, it completely replaces asbestos materials, fundamentally eliminating the occupational health risks posed by carcinogens.

[0019] Secondly, the installation process only requires placing each sealing block in sequence and manually splicing and pressing it, without any knocking, thus avoiding the risk of sealing block cracking and damage to the crystallizer copper plate, and greatly shortening the installation time.

[0020] Furthermore, by compensating for gap manufacturing tolerances through the controlled deformation of the elastic expansion ring, after the sealing sleeve is installed, regardless of how the gap size changes, as long as it is within the effective deformation range of the elastic expansion ring, a stable radial expansion force can be generated. This allows the sealing sleeve of the same specification to adapt to gap fluctuations within a certain range, and the sealing adaptability is improved by more than 50% compared with the integral structure.

[0021] Crucially, this invention establishes a synergistic working relationship between the mechanical pre-tightening provided by the elastic expansion ring and the high-temperature adhesive at the joint. During the room-temperature installation stage, the elastic expansion ring continuously provides circumferential compression force, pressing the adhesive applied at the joint into the microscopic gaps of the mortise and tenon structure, achieving a tight fit and initial seal at room temperature. After pouring, as the temperature rises, the adhesive and the sealing block substrate material co-sinter, and the joint area gradually fuses with the sealing block body. During the subsequent cooling process, the residual elastic recovery ability of the elastic expansion ring can compensate for thermal shrinkage, preventing the joint from cracking again due to thermal stress. This full-process sealing mechanism of "room-temperature pre-tightening and compaction, high-temperature sintering and curing, and cooling elastic compensation" is unprecedented in existing technologies.

[0022] Actual production tests have verified that the sealing sleeve of this invention can shorten the preparation time for casting from about 15 minutes with traditional asbestos rope sealing to less than 3 minutes, reduce the steel leakage rate to below 0.2%, increase the casting success rate to over 99.5%, and significantly reduce the wear of the copper plate in the crystallizer. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the overall assembly of Embodiment 1 of the sealing sleeve of the present invention.

[0024] Figure 2 yes Figure 1 A three-dimensional structural diagram of a single sealing block.

[0025] Figure 3 This is a schematic diagram of the overall assembly of Embodiment 2 of the sealing sleeve of the present invention.

[0026] Figure 4 This is a schematic diagram of the overall assembly of Embodiment 3 of the sealing sleeve of the present invention.

[0027] Figure 5 yes Figure 4 A schematic diagram showing the disassembly of the central sealing block.

[0028] Explanation of reference numerals in the attached diagram: 1. Sealing block; 2. Positioning protrusion; 3. Tenon; 4. Mortise; 5. Sealing surface; 6. Elastic expansion ring; 7. Die-starting head. Detailed Implementation

[0029] The following is in conjunction with the appendix Figure 1-5 The technical solutions of the present invention will be described in detail below with specific embodiments. It should be understood that the described embodiments are only for explaining the present invention and do not limit the scope of protection of the present invention.

[0030] Before describing the embodiments, the measurement methods for several key parameters are explained uniformly as follows:

[0031] The radial protrusion height of the elastic expansion ring 6 relative to the sealing surface 5 in the free state is measured as follows: At room temperature, using a ring gauge with an inner diameter equal to the nominal size of the crystallizer cavity as the measurement reference, before placing a single sealing block 1 or a spliced ​​sealing sleeve into the ring gauge, first use a height gauge or projector to measure the vertical distance from the top of the elastic expansion ring 6 to the base surface of the sealing surface 5. This is the radial protrusion height in the free state. The ratio of this height value to the maximum design gap between the sealing sleeve and the crystallizer should not be less than 1.2.

[0032] Example 1

[0033] Refer to the instruction manual appendix Figure 1-2 This embodiment is applied to a billet continuous casting machine with a cross-section of 280mm×320mm. The sealing sleeve is composed of two sealing blocks 1 spliced ​​together.

[0034] The sealing sleeve is composed of the following components by mass percentage: 80% zirconium ceramic fiber (ZrO2 content 15wt%, fiber average length 3mm), 15% silica sol as inorganic binder (solid content 30wt%), and the balance is 304 stainless steel short fibers with a length of 2mm to 4mm. After the above materials are mixed evenly in a mixer, they are molded under a pressure of 10MPa and dried in an oven at 120℃ for 4 hours. During molding, the tenon 3, mortise 4, positioning protrusion 2 and the outer V-shaped elastic tightening ring 6 are all integrally formed with the sealing block 1.

[0035] The height of the sealing sleeve after molding is 40mm, the inverted taper of the outer side is 1:30, and an elastic expansion ring 6 with a V-shaped cross section is provided on the outer sealing surface 5. The ring width is 8mm, and the radial protrusion height in the free state is 2.5mm. The maximum design gap applicable to this sealing sleeve is 2.0mm, and the ratio of the protrusion height to the maximum design gap is 1.25.

[0036] Before splicing, each sealing block 1 is coated with a layer of aluminum dihydrogen phosphate solution with a thickness of about 0.5 mm as a high-temperature adhesive on the mating surfaces of its tenon 3 and mortise 4.

[0037] During installation, insert the two sealing blocks 1 into the lower opening of the crystallizer in sequence and assemble them. Press them down with a little force until you hear a "click" sound to confirm that the positioning protrusion 2 has been inserted into the groove of the ingot head 7, and the installation is complete.

[0038] To verify the effect, 100 casting operations were performed on the same continuous casting machine using traditional asbestos rope, integral V-shaped ceramic fiber block (12mm thick) made according to CN118122971A scheme, and the sealing sleeve of this embodiment, respectively. The statistical results are shown in the table below.

[0039] asbestos rope 92% 15min 0.32mm 3.20% integral ceramic block 96% 8min 0.18mm 1.50% This embodiment 99.5% 2.8min 0.05mm 0.20%

[0040] The radial protrusion height of the elastic expansion ring 6 relative to the sealing surface 5 in the free state is measured as follows: At room temperature, using a ring gauge with an inner diameter equal to the nominal size of the crystallizer cavity as the measurement reference, before placing a single sealing block 1 or a spliced ​​sealing sleeve into the ring gauge, first use a height gauge or projector to measure the vertical distance from the top of the elastic expansion ring 6 to the base surface of the sealing surface 5. This is the radial protrusion height in the free state. The ratio of this height value to the maximum design gap between the sealing sleeve and the crystallizer should not be less than 1.2.

[0041] Example 2

[0042] Refer to the instruction manual appendix Figure 3 This embodiment is applied to a round billet continuous casting machine with a cross-sectional diameter of φ360mm. The sealing sleeve is composed of 4 sealing blocks 1 spliced ​​together.

[0043] The material ratio is adjusted to: 75% zirconium-containing ceramic fiber, 20% aluminum sol (solid content 25%), and 5% heat-resistant steel fiber (length 2mm-5mm). The sealing sleeve has a height of 50mm after molding and a taper of 1:40. An elastic expansion ring 6 with a U-shaped cross-section is provided on the outer sealing surface 5. The ring is 10mm wide, and the radial protrusion height in the free state is 3.0mm, corresponding to a maximum design gap of 2.4mm, with a ratio of 1.25. The joint is still coated with an aluminum dihydrogen phosphate solution with a thickness of approximately 0.6mm.

[0044] The round billet continuous casting machine produced 200 heats continuously, with an average installation time of 2.5 minutes before each casting. No steel leakage accidents caused by seal failure occurred during the production process, and no molten steel leakage was found after casting. There was no obvious wear in the copper plate sealing contact area of ​​the crystallizer.

[0045] Example 3

[0046] Refer to the instruction manual appendix Figure 4-5Based on Example 1, this embodiment further improves the layout of the elastic expansion ring 6 and the internal reinforcement structure of the joint. It is applied to a billet continuous casting machine with a cross-section of 180mm×180mm, and the sealing sleeve is composed of 4 sealing blocks 1.

[0047] The material ratio of the sealing sleeve is the same as that in Example 1, the molding height is 45mm, and the inverted taper is 1:35.

[0048] Unlike Embodiment 1, this embodiment features two parallel V-shaped elastic expansion rings 6 on the sealing surface 5 outside the sealing sleeve. These rings are distributed vertically along the height of the sealing sleeve, with a spacing of 10 mm. The V-shaped openings of the two expansion rings face opposite directions, with the upper expansion ring opening upwards and the lower expansion ring opening downwards. Each expansion ring is 5 mm wide, and in its free state, the radial protrusion height of a single ring is 1.2 mm. The total radial compensation capacity of the two rings is 2.4 mm. The maximum design gap in this example is 1.8 mm, with a ratio of 1.33.

[0049] In addition, a layer of high-temperature resistant metal mesh is embedded inside the mortise and tenon joint of adjacent sealing blocks 1. This metal mesh is made of nickel-chromium alloy, with a wire diameter of 0.2 mm and a mesh size of 1 mm × 1 mm, and is pre-cut into strips matching the length and width of the joint. After applying an aluminum dihydrogen phosphate solution, the metal mesh is pressed into the joint, and then a layer of adhesive is applied to the surface to fully impregnate the metal mesh and fill the mortise and tenon gap.

[0050] The installation method is the same as in Example 1. One hundred casting tests were conducted on the billet continuous casting machine, and the results were compared with those of Example 1 and the asbestos rope scheme. The results are as follows:

[0051] asbestos rope 92% 15min 0.32mm 3.20% — Example 1 99.5% 2.8min 0.05mm 0.20% 1 instance (slight air leakage) This embodiment 100% 2.6min 0.04mm 0% 0 times

[0052] The two V-shaped expansion rings with opposite openings provide a more uniform radial pressure distribution during installation, avoiding the localized pressure deficiency that may occur with a single ring. The embedded metal mesh, after sintering, is tightly wrapped by the ceramic matrix, acting as a reinforcing bar, significantly improving the thermal shock resistance and crack resistance at the joint. After 100 casting tests, no visible cracks were found in the joint area, and the ceramic-metal composite layer formed by the overall sintering of the sealing sleeve maintained its complete outline.

[0053] Comparative Example

[0054] To visually demonstrate the advantages of this invention over existing technologies, a comparative study was conducted using an integral V-shaped fiber block disclosed in CN118122971A on the same 280mm×320mm billet continuous casting machine as in Example 1. This fiber block is 12mm thick and requires repeated hammering with a copper hammer to embed. The average installation time was 5.5 minutes. In 30 installations, the fiber block cracked and was scrapped in 3 cases due to hammering. In 100 casting tests, two minor leaks occurred due to displacement of sealing block 1, one of which developed into a steel leakage incident.

[0055] In comparison, none of the embodiments of the present invention require hammering during installation, none of them result in damage to the sealing block 1, and none of them cause steel leakage due to seal displacement or seam penetration, demonstrating a significant difference in effectiveness.

[0056] It should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any simple substitutions, combinations or improvements made based on the technical concept of the present invention, as long as they do not depart from the spirit of the present invention, should be considered to fall within the scope of protection of the present invention.

[0057] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A sealing sleeve for the gap between the continuous casting ingot head and the crystallizer, characterized in that: Includes a sealing sleeve, which is pre-pressed from refractory material and is formed by splicing two or four sealing blocks (1) with inverted taper in the circumferential direction; The inner side of the sealing block (1) is provided with a positioning protrusion (2) for engaging with the circumferential groove on the outer wall of the ingot head (7) to limit the axial and radial displacement of the sealing sleeve. The outer side of the sealing block (1) is provided with a sealing surface (5) opposite to the inner wall of the crystallizer. At least one elastic expansion ring (6) is integrally formed on the sealing surface (5) along the circumferential direction. The cross section of the elastic expansion ring (6) is V-shaped or U-shaped, and its radial protrusion height relative to the sealing surface (5) in the free state is not less than 1.2 times the maximum design gap between the sealing sleeve and the crystallizer. The mating surfaces of adjacent sealing blocks (1) are respectively provided with tenons (3) and mortises (4) that can mesh with each other, forming a mortise and tenon structure; An inorganic high-temperature adhesive for high-temperature sintering and curing is applied to the mating surfaces of the tenon (3) and the mortise (4) and at their joint.

2. The sealing sleeve for the gap between the continuous casting ingot head and the crystallizer according to claim 1, characterized in that: The refractory material is a molded composite material of zirconium-containing ceramic fibers, inorganic binders, and chopped heat-resistant steel fibers, wherein the mass percentage of zirconium-containing ceramic fibers is 70% to 85%, the inorganic binder is silica sol or alumina sol, and the balance is chopped heat-resistant steel fibers, the length of which is 2 mm to 5 mm.

3. The sealing sleeve for the gap between the continuous casting ingot head and the crystallizer according to claim 1, characterized in that: The inverted taper of the sealing sleeve is 1:20 to 1:50, and the height of the sealing sleeve is 30mm to 60mm.

4. The sealing sleeve for the gap between the continuous casting ingot head and the crystallizer according to claim 1, characterized in that: The number of elastic expansion rings (6) is two, which are distributed in parallel up and down along the height direction of the sealing sleeve, and the V-shaped or U-shaped openings of the two elastic expansion rings (6) are opposite.

5. The sealing sleeve for the gap between the continuous casting ingot head and the crystallizer according to claim 1, characterized in that: The joint of the mortise and tenon structure is also embedded with a layer of high-temperature resistant metal mesh, which is impregnated and wrapped by the high-temperature adhesive.

6. The sealing sleeve for the gap between the continuous casting ingot head and the crystallizer according to claim 1, characterized in that: The high-temperature binder is an aluminum dihydrogen phosphate solution.

7. A method for sealing continuous casting ingots using the sealing sleeve described in any one of claims 1 to 6, characterized in that... Includes the following steps: (a) Select the corresponding sealing sleeve according to the cross-sectional dimensions of the crystallizer cavity and the outer diameter of the ingot head (7); (b) The sealing blocks (1) of the sealing sleeve are sequentially fed into the lower opening of the crystallizer and spliced ​​into a complete rectangular or circular sealing sleeve by means of the mortise and tenon structure. (c) Press down on the assembled sealing sleeve so that the positioning protrusion (2) on its inner side is inserted into the groove on the outer wall of the ingot head (7). At the same time, the elastic expansion ring (6) on the outer side of the sealing sleeve is subjected to radial compression of the inner wall of the crystallizer, resulting in elastic deformation and forming an initial interference seal between the sealing sleeve and the inner wall of the crystallizer. (d) After pouring, the high-temperature adhesive at the sealing sleeve and joint is sintered and solidified at the high temperature of the molten steel, forming a dense sealing layer.

8. The sealing method according to claim 7, characterized in that, In step (c), the radial deformation of the elastic expansion ring (6) caused by compression is 0.2 mm to 1.0 mm.

9. The sealing method according to claim 7 or 8, characterized in that, The sealing sleeve is the sealing sleeve according to claim 4 or 5. In step (c), two elastic expansion rings (6) with opposite opening directions provide radial expansion force to form a uniform initial interference seal.

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