Stepless heat preservation cap mouth structure

Abstract

The utility model relates to steel ingot casting technical field especially no step heat preservation cap mouth structure, it includes mud cap mouth, iron cap mouth and heat preservation cover. Mud cap mouth is conical, and the inner chamber adopts octagonal plum blossom shape taper structure, and the taper range is 0.8% 1.5%, iron cap mouth includes circular ring and lug, and is installed in close cooperation with mud cap mouth, heat preservation cover is composed of stone wool heat preservation board and metal sheet, and covers in the periphery to reduce the cooling rate. The utility model discloses through optimizing the inner chamber shape and cancelling step structure, reduces stress concentration and slag inclusion defect, significantly improves the billet yield, is applicable to electric furnace ingot and other metal ingot casting process.

Description

Technical Field

[0001] This utility model belongs to the field of thermal insulation container manufacturing technology, specifically a stepless thermal insulation cap structure. Background Technology

[0002] In the steel ingot casting process, the cavity of the cap is a hollow space for storing molten steel. It is placed directly on top of the ingot mold and replenishes the ingot with molten steel as it forms. It serves to prevent shrinkage cavities and porosity, expel air, and collect slag. The main function of the cap is to compensate for shrinkage. Usually, the cap portion is removed after processing. Existing caps for round and polygonal steel ingot molds are cylindrical. With the booming development of the automotive industry, most die-casting molds are gradually becoming larger and more integrated. Because integrated die-casting molds require steel with good mechanical and machinability properties, electric furnace steel is often used to ensure product performance meets requirements. However, electric furnace ingots produced by electric furnaces have internal porosity, leading to stress cracks at the cap during forging. In existing cap designs, the inner cavity size of the cap is usually similar to the upper opening size of the ingot mold's inner cavity, and the upper and lower diameters of the cap cavity are the same, both being inner cavity size A. This design is difficult to effectively alleviate stress concentration during the ingot solidification process in practical applications, making the cap prone to cracking. In actual steel ingot production, to reduce the amount of cap removal, the inner cavity size A of the cap is generally smaller than the upper opening size B of the ingot mold cavity. When using existing cap types for steel ingot casting, as molten steel is continuously poured into the ingot mold, the protective slag covering the surface of the molten steel gradually rises with it. Because the lower diameter of the cap cavity is smaller than the upper diameter, when the molten steel is poured near the cap line, some of the protective slag covering the surface of the molten steel stops rising due to the obstruction of the lower edge of the cap cavity. During the subsequent solidification of the molten steel, the protective slag accumulated at the lower edge C of the cap cavity becomes embedded in the surface of the ingot body, forming inclusion defects. Some inclusions even extend deeper into the ingot body. These inclusions will further affect the surface quality of the product during subsequent processing. After casting, the steel ingots are either rolled or forged into finished products of corresponding specifications. Both the head (cap portion) and tail (tail portion) of the finished ingot must be removed. Head removal is necessary because the surface of the steel billet is affected by insulating plates, protective slag, etc., which affect surface quality; tail removal is necessary to meet the finished product specifications. Generally, the head and tail removal rates vary depending on the product and specifications; the head removal rate is approximately 14%-18%, and the tail removal rate is approximately 3%-5%, indicating that the head removal rate significantly impacts the billet yield. The aforementioned defects such as slag inclusions and cap cracks directly affect the head removal rate. Therefore, optimizing the cap structure design to reduce cap cracks and slag inclusion defects can significantly improve the billet yield. Utility Model Content

[0003] The purpose of this utility model is to provide a stepless heat-insulating cap structure, which, while fulfilling the basic functions of feeding, venting and slag collection during the steel ingot casting process, also has the function of reducing cap stress and eliminating slag inclusions and loose defects at the lower edge of the cap, thereby significantly improving the yield of steel billets.

[0004] To achieve the aforementioned utility model objectives, this utility model provides a stepless heat-insulating cap structure, comprising a mud cap, an iron cap, and a heat-insulating cover. The mud cap is conical, comprising an outer ring and an inner cavity. The outer ring is circular, and the inner cavity has a tapered structure. The inner cavity is composed of eight arc-shaped surfaces, each convex inward, with adjacent arc-shaped surfaces smoothly transitioning through connecting arc surfaces to form an octagonal plum blossom-shaped structure. The upper diameter of the mud cap is smaller than the lower diameter, and its taper ranges from 0.8% to 1.5% to accommodate the requirements of ingots of different specifications. The iron cap opening includes a ring and a lug. The lug is symmetrically fixed to the outside of the ring. The inner diameter of the ring matches the outer diameter of the mud cap opening. The two are installed and positioned by a tight fit. The iron cap opening is used to support the mud cap opening and ensure its stability during the pouring process. The insulation cover consists of an inner layer and an outer layer. The inner layer is an asbestos insulation board, and the outer layer is a metal plate. The insulation cover covers the periphery of the mud cap opening and the iron cap opening to reduce the cooling rate of the steel ingot.

[0005] To address the technical problems of internal porosity and cap cracks in electric furnace ingots, the aforementioned stepless insulating cap structure provided by this utility model redesigns the inner cavity shape of the mud cap, adopting an octagonal plum blossom-shaped structure with a gradually tapering conical inner cavity. This design allows the molten steel to uniformly contract towards the center during solidification, reducing stress concentration caused by uneven solidification. Simultaneously, the conical design of the mud cap increases the size of the lower opening, making it consistent with the upper opening of the ingot mold. This avoids the problem of slag stagnation and floating at the lower edge of the cap, as seen in existing technologies. Furthermore, the stepless forging process prevents cap folding cracks, which can lead to excessively high cuts and reduced yield. In addition, the mud cap's splicing structure consists of eight independent mud cap blocks, each spliced ​​together using an interlocking method and secured by embedded iron wire, facilitating installation and disassembly.

[0006] To optimize the insulation effect of the cap opening, this invention adds an insulation cover structure to the outside. The inner layer of the insulation cover uses asbestos insulation board, which has a low thermal conductivity and can effectively slow down the cooling rate of the steel ingot, reducing internal defects caused by rapid cooling; the outer layer uses a metal plate to provide protection and prevent damage to the insulation cover from the external environment. The insulation cover is fixed to the outside of the mud cap opening and the iron cap opening by mechanical compression to ensure that it will not shift during the casting process.

[0007] This invention further improves the design of the iron cap opening by eliminating the stepped structure in traditional cap openings, resulting in a better size match between the iron cap opening and the mud cap opening. Specifically, the inner diameter of the circular ring of the iron cap opening is consistent with the outer diameter of the mud cap opening, and the two achieve installation positioning through a tight fit, avoiding stress concentration problems caused by the stepped structure. In addition, the lugs of the iron cap opening are symmetrically distributed for hoisting and fixing the entire cap opening structure, ensuring its stability during the casting process.

[0008] In practical applications, the mud cap is baked and then installed inside the iron cap. The two are secured together by embedding wood chips at their junction to ensure a firm installation. Subsequently, the assembled cap structure is placed into the steel ingot mold, and molten steel is poured in according to the process specifications. After pouring, an insulation cover is placed over the top of the steel ingot mold to further reduce the cooling rate of the molten steel and minimize the occurrence of internal defects.

[0009] Optionally, in the stepless heat-insulating cap structure of this utility model, the inner cross-section of the mud cap opening can be circular or polygonal to adapt to different types of steel ingot molds. Optionally, in the stepless heat-insulating cap structure of this utility model, the taper of the mud cap opening can be adjusted according to the ingot specifications to meet the solidification requirements of different steel ingots. Optionally, the inner cavity shape of the mud cap opening can be either an octagonal plum blossom shape or other polygonal structures, as long as it can achieve the effect of uniform shrinkage and reduced stress concentration. Optionally, in the stepless heat-insulating cap structure of this utility model, the number of mud cap blocks can be adjusted according to actual needs, preferably 8 blocks, to facilitate installation and disassembly. Optionally, the thickness of the insulation cover can be adjusted according to the cooling rate requirements of the steel ingot. Typically, the thickness of the inner asbestos insulation board is 20mm to 50mm, and the thickness of the outer metal plate is 1mm to 3mm.

[0010] Preferably, the connection between the mud cap opening and the iron cap opening is a fitting method, and is filled and tightened with wood chips to ensure a firm installation and easy disassembly. Optionally, the number of lugs on the iron cap opening can be two or four, symmetrically distributed on the outside of the ring, for hoisting and fixing the entire cap opening structure.

[0011] Beneficial effects: The stepless heat-insulating cap structure provided by this utility model solves the technical problems of internal porosity and stress cracking at the cap opening by optimizing the inner cavity shape and taper design of the mud cap opening. Simultaneously, by adding a heat-insulating cover structure, the cooling rate of the steel ingot is reduced, minimizing internal defects caused by rapid cooling. Furthermore, eliminating the step structure in the traditional cap opening allows for a better size match between the iron cap opening and the mud cap opening, further reducing stress concentration. In summary, this utility model significantly improves the yield of steel ingots by 15% to 20% through a redesigned cap opening structure. The stepless heat-insulating cap structure provided by this utility model is not only suitable for casting electric furnace ingots but can also be widely applied to the casting processes of other metals. Attached Figure Description

[0012] Figure 1 This is a top view of the mud cap opening in this utility model. Figure 2 This is a side view of the iron cap opening in this utility model. Figure 3 This is a side view of the heat insulation cover and steel ingot mold in this utility model.

[0013] The attached diagram is labeled as follows: 1. Mud cap opening; 2. Iron cap opening; 3. Insulation cover; 4. Hanging lug; 5. Inner cavity; 6. Outer ring; 7. Arc-shaped surface; 8. Connecting arc surface; 9. Steel ingot mold. Detailed Implementation

[0014] The stepless heat-insulating cap structure of this utility model mainly consists of a mud cap 1, an iron cap 2, and a heat-insulating cover 3. Its specific implementation method is as follows: [Combined with...] Figure 1 As shown, the mud cap opening 1 has a conical structure, including an outer ring 6 and an inner cavity 5. The outer ring 6 is circular, while the inner cavity 5 is designed with a tapering structure and consists of eight arc-shaped surfaces 7. Adjacent arc-shaped surfaces 7 are smoothly transitioned by connecting arc surfaces 8, forming an octagonal plum blossom-shaped cross-sectional structure. The upper diameter of the mud cap opening 1 is smaller than the lower diameter, with a taper ranging from 0.8% to 1.5% to accommodate the needs of ingots of different sizes. The conical design of the mud cap opening 1 ensures that its upper opening size matches that of the steel ingot mold in actual use, avoiding slag inclusion problems caused by size mismatch. The mud cap opening 1 is composed of eight independent mud cap opening blocks, each of which is assembled into a whole through an interlocking method and fixed by embedded iron wires for easy installation and disassembly.

[0015] The iron cap opening 2 includes a circular ring and lugs 4. The lugs 4 are symmetrically fixed to the outside of the circular ring for hoisting and securing the entire cap opening structure. The inner diameter of the circular ring of the iron cap opening 2 matches the outer diameter of the mud cap opening 1; the two achieve installation positioning through a tight fit. In actual assembly, the mud cap opening 1 is baked before being installed inside the iron cap opening 2. The junction between the two is secured with embedded sawdust to ensure a firm installation and easy disassembly. The design of the iron cap opening 2 eliminates the stepped structure found in traditional cap openings, making the dimensions of the iron cap opening 2 and the mud cap opening 1 more closely match, thereby effectively reducing stress concentration.

[0016] The insulation cover 3 consists of an inner layer and an outer layer. The inner layer is an asbestos insulation board, and the outer layer is a metal plate. Figure 1 As shown, the insulation cover 3 covers the outer perimeter of the mud cap 1 and the iron cap 2, and is fixed by mechanical clamping to ensure that it will not shift during the pouring process. The inner layer of asbestos insulation board is 20mm to 50mm thick, and the outer layer of metal plate is 1mm to 3mm thick. This double-layer structure design can effectively slow down the cooling rate of the steel ingot, while preventing damage to the insulation cover 3 from the external environment. The covering method of the insulation cover 3 further reduces the cooling rate of the molten steel, reducing internal defects caused by rapid cooling.

[0017] In practical applications, the inner cavity 5 of the mud cap opening 1 is designed with an octagonal plum blossom-shaped structure, such as... Figure 2 As shown, its arc-shaped surface 7 bulges inward, and adjacent arc-shaped surfaces 7 are smoothly transitioned by connecting arc-shaped surfaces 8. The tapered design of the inner cavity 5 allows the molten steel to uniformly shrink towards the center during the solidification process of the ingot, avoiding stress concentration caused by uneven solidification. The taper of the mud cap opening 1 can be adjusted according to the ingot specifications to meet the solidification requirements of different ingots. In addition, the cross-section of the inner cavity 5 of the mud cap opening 1 can also be designed as circular or polygonal according to actual needs to adapt to different types of ingot molds.

[0018] The number of lugs 4 on the iron cap opening 2 can be two or four, symmetrically distributed on the outer side of the ring, used for hoisting and fixing the entire cap opening structure. The design of the lugs 4 ensures the stability of the cap opening structure during the casting process, while also facilitating installation and disassembly by operators. The inner diameter of the ring of the iron cap opening 2 is consistent with the outer diameter of the mud cap opening 1. The two achieve installation positioning through a tight fit, avoiding stress concentration problems caused by size mismatch.

[0019] In the actual casting process, the eight independent mud cap pieces 1 are first assembled into a whole and fixed by embedding iron wire. Then, after baking, the assembled mud cap 1 is installed inside the iron cap 2, with sawdust embedded at the junction to ensure a secure fit. The assembled cap structure is placed into the steel ingot mold, and molten steel is poured in according to the process specifications. After pouring, an insulation cover 3 is placed over the top of the steel ingot mold to further reduce the cooling rate of the molten steel and minimize internal defects.

[0020] The octagonal, plum blossom-shaped inner cavity 5 of the mud cap opening 1 allows the molten steel to uniformly contract towards the center during solidification, reducing stress concentration caused by uneven solidification. Simultaneously, the conical design of the mud cap opening 1 increases the size of the lower opening, making it consistent with the upper opening of the ingot mold, thus avoiding the problem of protective slag stagnating and floating at the lower edge of the cap opening in existing technologies. The stepless design of the iron cap opening 2 further reduces stress concentration, while the covering of the insulation cover 3 significantly slows down the cooling rate of the ingot, reducing internal defects caused by rapid cooling.

[0021] The connection between the mud cap 1 and the iron cap 2 is an interlocking method, and is secured with wood chips to ensure a firm installation and easy disassembly. The thickness of the insulation cover 3 can be adjusted according to the cooling rate requirements of the steel ingot; typically, the inner asbestos insulation board is 20mm to 50mm thick, and the outer metal plate is 1mm to 3mm thick. This design not only meets the basic functions of feeding, venting, and slag collection during the steel ingot casting process, but also significantly improves the yield of steel billets.

[0022] In the actual casting process, the eight independent clay cap blocks of clay cap 1 are first assembled into a whole. Each clay cap block is assembled by interlocking and fixed by embedded iron wire to ensure its stability during installation and use. Then, the assembled clay cap 1 is baked to achieve a suitable dryness, preventing porosity defects caused by residual moisture during casting. After baking, clay cap 1 is installed inside iron cap 2, with the junction secured by embedded wood chips to ensure a firm installation and easy subsequent disassembly. The inner diameter of the annular ring of iron cap 2 is consistent with the outer diameter of clay cap 1. This tight-fitting design eliminates the stepped structure in traditional caps, effectively reducing stress concentration problems caused by dimensional mismatch.

[0023] The assembled cap structure is then placed into the ingot mold, and molten steel is poured in according to the process specifications. Because the inner cavity 5 of the mud cap 1 is designed as an octagonal, plum blossom-shaped structure, with its arc-shaped surfaces 7 convex inwards and adjacent arc-shaped surfaces 7 smoothly transitioning through connecting arc-shaped surfaces 8, this tapering design allows the molten steel to uniformly contract towards the center during solidification. Specifically, after the molten steel is poured in, as the temperature gradually decreases, the molten steel solidifies gradually from the outside towards the center, and the octagonal, plum blossom-shaped inner cavity 5 provides a more uniform cooling path, avoiding stress concentration caused by excessively rapid local cooling. Furthermore, the taper of the mud cap 1 ranges from 0.8% to 1.5%, and its lower diameter is larger than its upper diameter. This design ensures that the lower opening size of the cap matches the upper opening size of the ingot mold, thus avoiding the problem of protective slag stagnating and floating at the lower edge of the cap, as is common in existing technologies. When the protective slag rises with the molten steel surface, it is not blocked by the lower edge of the cap cavity, but floats smoothly to the top of the cap, reducing the occurrence of slag inclusion defects.

[0024] After casting, an insulation cover 3 is placed over the top of the ingot mold 9 to further reduce the cooling rate of the molten steel. The insulation cover 3 consists of an inner asbestos insulation board with a thickness of 20mm to 50mm and an outer metal plate with a thickness of 1mm to 3mm. This double-layer structure not only slows down the cooling rate of the ingot but also prevents damage to the insulation cover 3 from the external environment. In practical applications, the insulation cover 3 is mechanically clamped to the periphery of the mud cap opening 1 and the iron cap opening 2 to ensure that it does not shift during casting. By slowing down the cooling rate, the insulation cover 3 significantly reduces internal defects caused by rapid cooling, such as porosity and cracks, thereby improving the overall quality of the ingot.

[0025] The number of lugs 4 on the iron cap opening 2 can be two or four, symmetrically distributed on the outer side of the ring, for hoisting and fixing the entire cap opening structure. The design of the lugs 4 ensures the stability of the cap opening structure during the casting process, while also facilitating installation and disassembly by operators. The stepless design of the iron cap opening 2 further optimizes the fit between the cap opening and the steel ingot mold, avoiding stress concentration problems caused by the stepped structure. In practical applications, this design can significantly reduce the possibility of stress cracks at the cap opening location, thereby improving the yield of steel billets.

[0026] During the solidification process of the steel ingot, the conical design of the mud cap 1 and its combination with the octagonal plum blossom-shaped inner cavity 5 play a crucial role. The conical design increases the size of the lower opening of the cap, making it consistent with the size of the upper opening of the steel ingot mold, thereby avoiding the problem of the protective slag stagnating and floating at the lower edge of the cap. The octagonal plum blossom-shaped inner cavity 5 guides the molten steel to shrink evenly through its tapering structure, reducing stress concentration caused by uneven solidification. In addition, the mud cap 1 is composed of eight independent mud cap blocks, each of which is assembled into a whole through a fitting method and fixed by embedded iron wire, facilitating installation and disassembly. This modular design not only improves the flexibility of the cap's use but also reduces maintenance costs.

[0027] In summary, the stepless heat-insulating cap structure provided by this utility model solves the problems of stress cracks and slag inclusions in the existing technology by optimizing the inner cavity shape and tapered design of the mud cap 1 and increasing the covering method of the heat-insulating cover 3. In practical applications, this structure significantly improves the yield of steel ingots, increasing it by 15% to 20%. The design of this utility model is not only suitable for electric furnace ingot casting, but can also be widely applied to the ingot casting process of other metals, and has high practical value and promising prospects for promotion.

Claims

1. A stepless heat-insulating cap structure, characterized in that: It includes a mud cap opening (1), an iron cap opening (2), and a heat insulation cover (3). The mud cap opening (1) is conical, including an outer ring (6) and an inner cavity (5). The outer ring (6) is circular, and the inner cavity (5) is a tapered structure composed of eight arc-shaped surfaces (7). Adjacent arc-shaped surfaces (7) are smoothly transitioned by connecting arc surfaces (8) to form an octagonal plum blossom-shaped structure. The upper diameter of the mud cap opening (1) is smaller than the lower diameter, and the taper range is 0.8%-1.5%. The iron cap opening (2) includes a ring and a lug (4). The lug (4) is symmetrically fixed to the outside of the ring. The inner diameter of the ring matches the outer diameter of the mud cap opening (1). The two are installed and positioned by close cooperation. The heat insulation cover (3) consists of an inner layer and an outer layer. The inner layer is an asbestos insulation board, and the outer layer is a metal plate. The heat insulation cover (3) covers the periphery of the mud cap opening (1) and the iron cap opening (2).

2. The stepless heat-insulating cap structure as described in claim 1, characterized in that, The cross-section of the inner cavity (5) of the mud cap opening (1) is circular or polygonal.

3. The stepless heat-insulating cap structure as described in claim 1, characterized in that, The mud cap opening (1) is composed of eight independent mud cap opening blocks. Each mud cap opening block is spliced ​​together into a whole by interlocking and is fixed by the embedded iron wire.

4. The stepless heat-insulating cap structure as described in claim 1, characterized in that, The inner asbestos insulation board of the heat insulation cover (3) has a thickness of 20-50mm, and the outer metal plate has a thickness of 1-3mm.

5. The stepless heat-insulating cap structure as described in claim 1, characterized in that, The number of lugs (4) on the iron cap opening (2) is two or four, symmetrically distributed on the outside of the ring.

6. The stepless heat-insulating cap structure as described in claim 1, characterized in that, The junction between the mud cap opening (1) and the iron cap opening (2) is secured by embedding wood chips.

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