Heat transfer structure of super-large section special-shaped blank crystallizer

Abstract

The invention belongs to the technical field of ferrous metallurgy, and relates to a heat transfer structure of a super-large-section special-shaped blank crystallizer. The crystallizer comprises a wide panel (A) and a narrow panel (B), a plurality of water seams (9) are formed in the narrow panel inner wall (8) of the narrow panel (B), a plurality of concave structures (10) and a plurality of convex structures (16) are arranged on the inner wall of each water seam (9) of a steel flow impact area (11) of the narrow panel (B), and the narrow panel (B) comprises a narrow panel inner wall (8), an upper end (13) and a lower end (12). And the water seam (9) is of a groove structure arranged on the inner wall (8) of the narrow panel piece. According to the heat transfer structure of the super-large-section special-shaped blank crystallizer, the heat transfer efficiency is effectively improved, the heat transfer requirement of super-large-section special-shaped blank continuous casting is effectively met, and therefore the product machining quality is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of iron and steel metallurgy, and more specifically, relates to a heat transfer structure of a super-large section special-shaped blank crystallizer. Background Art

[0002] H-beam has been widely used in various fields due to its product characteristics. With the development of the economy, customers have increasingly demanded H-beam with super large specifications and high performance in recent years. As a near-final product, profiled billets have unparalleled advantages over other cast billets in the rolling production of H-beam. Therefore, it is of great significance to research and develop the continuous casting technology of super-large profiled billets. As the "heart" of the continuous casting machine, the design and manufacture of the crystallizer is one of the core technologies of continuous casting. The key technology for continuous casting of super-large section profiled billets lies in the efficient heat transfer of the crystallizer to meet the higher heat transfer requirements of the molten steel inside. The commonly used special-shaped billet crystallizer is composed of two narrow copper plates and two wide copper plates. The narrow copper plate is a regular cuboid with a rectangular water trough on the outside. The wide copper plate has a rectangular surface on the outside and a convex structure on the inside. There are several circular water holes inside the copper plate. The raised part on the inside of the wide copper plate is called the web, and the horizontal parts on both sides are the wings. The raised part and the horizontal part are connected by a slope surface, called the bevel. The bevel and the web are connected by a larger circular chamfer, called the large R angle, and the bevel and the wings are connected by a smaller fillet, called the small R angle. The inner cavity of the crystallizer after the four copper plates are combined is "H" shaped. The heat transfer behavior of the crystallizer is one of the key factors affecting the quality of the billet. The heat transfer of the crystallizer is mainly achieved by the circulating cooling water in the copper plate to take away the heat. Therefore, the design of the cooling water channel in the copper plate is the core of the design and manufacture of the crystallizer. The cooling water channels of the two wide and two narrow sides of the special-shaped billet are basically arranged symmetrically; the cooling water channels of the narrow copper plate are basically rectangular water gaps. The inner walls of the cooling water channels of the currently used crystallizer copper plates are mostly smooth walls. The cooling water flows smoothly and has low turbulent kinetic energy, so the heat exchange efficiency is low. At the same time, due to the weak turbulence of the cooling water and the low water flow velocity on the inner wall, impurities in the water are easily deposited and scaled, resulting in a deterioration of the cooling effect. Some patents have designed rectangular water seams with concave and convex bottoms, or current limiting rods in spiral, serrated and other shapes to increase the turbulent intensity of the cooling water, thereby improving the heat transfer efficiency. However, the current design of the water cooling channel of the copper plate of the special-shaped billet may have high processing costs and great difficulty in maintenance and repair; or the adaptability and flexibility of the wide copper plate of the special-shaped billet with relatively complex shapes and heat dissipation characteristics is insufficient, which easily leads to uneven temperature on the inner surface of the copper plate. It cannot fully meet the continuous casting needs of super-large special-shaped billets.

[0003] In the prior art, there is a technology named "A High-efficiency Heat Transfer Type Shaped Blank Continuous Casting Crystallizer" and the publication number is "CN102303103A", which relates to a high-efficiency heat transfer type shaped blank continuous casting crystallizer, wherein the inner wall surface of the rectangular groove and the inner wall surface of the circular hole are both provided with protrusions or depressions that form an uneven rough surface on the inner wall surface; the outer peripheral surface of the inserted metal object is provided with protrusions or depressions, or the metal object is a spiral line, spiral belt, spiral sheet, cross-serrated belt, twisted belt, threaded rod or static mixer that can form an uneven water gap between itself and the circular hole. The use of the present invention can improve the flow behavior of cooling water in the crystallizer, increase the heat exchange efficiency of the crystallizer cooling water, reduce scaling on the cooling water channel wall, and extend the service life of the crystallizer copper plate. However, this technology does not involve the technical problems and technical solutions of the present application. Summary of the invention

[0004] The technical problem to be solved by the present invention is: in view of the shortcomings of the prior art, a heat transfer structure for a super-large cross-section special-shaped billet crystallizer is provided which has a simple structure, effectively improves the heat transfer efficiency, effectively meets the heat transfer requirements of the continuous casting of super-large cross-section special-shaped billets, and thus improves the processing quality of the product.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is:

[0006] The present invention is a heat transfer structure of a super-large section special-shaped blank crystallizer. The crystallizer comprises a wide panel member and a narrow panel member. A plurality of water gaps are arranged on the inner wall of the narrow panel member. A plurality of recessed structures and a plurality of protruding structures are arranged on the inner wall of each water gap in the steel flow impact area of ​​the narrow panel member. The narrow panel member comprises an inner wall, an upper end and a lower end of the narrow panel member. The water gap is a groove structure arranged on the inner wall of the narrow panel member.

[0007] The wide panel member of the wide panel member is provided with a plurality of large holes on the inner wall near the web position, the wide panel member of the wide panel member is provided with a plurality of small holes on the inner wall near the R angle position, the wide panel member is provided with a first group of multiple small holes near the large hole position, and the wide panel member is further provided with a second group of multiple small holes at the first group of multiple small holes near the R angle position, a limiting rod passes through each large hole, a spiral threaded portion is provided on the surface of the limiting rod, and a gap is provided between the limiting rod and the inner wall of the large hole.

[0008] The wide panel member has a plurality of small holes arranged near the inclined surface on the inner wall of the wide panel member, and a second group of small holes is arranged at the first group of small holes near the inclined surface on the inner wall of the wide panel member.

[0009] The inner wall of the wide panel member of the wide panel member is provided with a plurality of small holes near the wing tip.

[0010] The diameter φ of the large hole on the inner wall of the wide panel member close to the web is between 20 mm and 25 mm; the diameter φ of the current limiting rod is between 10 mm and 15 mm.

[0011] The diameter φ of the small hole on the inner wall of the wide panel member near the large hole is 10-15 mm, and the diameter φ of the small hole on the inner wall of the wide panel member near the R angle is 10 mm-15 mm.

[0012] The diameter φ of the small hole on the inner wall of the wide panel member near the inclined surface is 10mm-15mm, and the diameter φ of the small hole on the inner wall of the wide panel member near the inclined surface is 10mm-15mm.

[0013] The diameter φ of the small hole on the inner wall of the wide panel member near the wing tip is between 10 mm and 15 mm.

[0014] The wide panel member and the narrow panel member each include two, and both the wide panel member and the narrow panel member are structures made of copper plate material.

[0015] The wide panel member has a flat outer wall, a convex inner wall, and a web, an R angle, a slope and a wing tip.

[0016] The technical solution of the present invention is adopted, and the working principle and beneficial effects are as follows:

[0017] The heat transfer structure of the super-large section profiled blank crystallizer described in the present invention is that when the structure is set, the wide panel member and the narrow panel member of the crystallizer are improved respectively. The wide panel member and the narrow panel member each include two pieces, the narrow panel member can be a copper plate, the narrow panel member structure is a regular rectangular parallelepiped, the narrow panel member inner wall is provided with multiple water slits, and the inner wall of each water slit in the steel flow impact area of ​​the narrow panel member is respectively provided with multiple recessed structures and multiple protruding structures, the narrow panel member includes the inner wall of the narrow panel member, the upper end and the lower end, and the water slit is a groove structure arranged on the inner wall of the narrow panel member. The key improvement point of the structure of the present invention is that the steel flow impact area on the surface of the narrow panel member is designed for local turbulence enhancement, and the area adopts multiple recessed structures and multiple protruding structures arranged in an alternating manner on the inner wall of the water slit, and the multiple recessed structures and multiple protruding structures on the inner wall of each water slit are concave-convex structures, thereby increasing the turbulence intensity of the cooling water, thereby improving the local heat transfer efficiency. When the structure of the wide panel member is improved, the outer wall of the wide panel member (the outer wall surface of the wide panel member) is a rectangular surface, and the inner wall of the wide panel member (the inner wall surface of the wide panel member) is convex, including a raised web in the middle, symmetrical wings on both sides, an inclined surface connecting the web and the wing tip 4, a large R angle where the inclined surface intersects with the web, and a small R angle where the inclined surface intersects with the wing tip. Vertical circular holes are drilled along the edge of the inner wall of the wide panel member, and the water cooling holes of the wide panel member A are designed in a double-layer layout, including large holes and small holes. A circular water cooling hole is designed in the inner layer of the web, and a flow limiting rod is inserted into the circular water hole. There is a gap between the circular water hole and the flow limiting rod to form an annular cooling water gap; the flow limiting rod adopts stainless steel threaded steel bars, and the raised pattern on the surface of the threaded steel bars is used to increase the turbulence intensity of the cooling water, thereby improving the heat transfer efficiency; a water cooling circular hole is designed in the outer layer of the web to further improve the heat transfer efficiency and heat transfer uniformity. The water-cooling circular holes designed in the inner layer of the R angle and the bevel respectively adapt to the complex heat transfer characteristics of the profiled blank through the reasonable layout design of the water-cooling holes to improve the uniformity of the temperature distribution on the inner wall of the wide panel. A small number of water-cooling circular holes are also designed in the outer layer of the R angle and the bevel to increase the heat transfer efficiency. The wing tip is designed with a single layer of water-cooling circular holes to match the relatively low heat transfer requirements of the wing tip. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The following is a brief description of the contents and symbols in the drawings of this specification:

[0019] Figure 1 It is a schematic cross-sectional structure diagram of a wide panel member of the heat transfer structure of the super-large section profiled blank crystallizer according to the present invention;

[0020] Figure 2 It is a top view structural schematic diagram of the narrow panel member of the heat transfer structure of the super-large section profiled blank crystallizer according to the present invention;

[0021] The marks in the accompanying drawings are respectively: A, wide panel member; B, narrow panel member; 1, web; 2, R angle; 3, inclined surface; 4, wing tip; 5, outer wall of wide panel member; 6, large hole; 7, small hole; 8, inner wall of narrow panel member; 9, water gap; 10, recessed structure; 11, steel flow impact area; 12, lower end; 13, upper end; 14, flow limiting rod; 15, gap; 16, protruding structure; 17, outer wall of wide panel member; 18, small R angle. DETAILED DESCRIPTION

[0022] The following is a further detailed description of the specific implementation of the present invention, such as the shape, structure, mutual position and connection relationship between the various components involved, the function and working principle of each part, etc., through the description of the embodiments with reference to the accompanying drawings:

[0023] As attached Figure 1 , Attachment Figure 2 As shown, the present invention is a heat transfer structure of a super-large section profiled blank crystallizer, the crystallizer comprises a wide panel member A and a narrow panel member B, a plurality of water slots 9 are arranged on the inner wall 8 of the narrow panel member B, a plurality of recessed structures 10 and a plurality of protruding structures 16 are arranged on the inner wall of each water slot 9 in the steel flow impact area 11 of the narrow panel member B, the narrow panel member B comprises the inner wall 8 of the narrow panel member, an upper end 13 and a lower end 12, the water slot 9 is a groove structure arranged on the inner wall 8 of the narrow panel member. The above structure proposes an improved technical solution to address the deficiencies in the prior art. When setting the structure, the wide panel member A and the narrow panel member B of the crystallizer are improved respectively. The wide panel member A and the narrow panel member B respectively include two pieces, the narrow panel member B can be a copper plate, the narrow panel member B has a regular rectangular structure, a plurality of water slits 9 are arranged on the inner wall 8 of the narrow panel member B, and a plurality of recessed structures 10 and a plurality of protruding structures 16 are arranged on the inner wall of each water slit 9 in the steel flow impact area 11 of the narrow panel member B, and the narrow panel member B includes the inner wall 8 of the narrow panel member, the upper end 13 and the lower end 12, and the water slit 9 is a groove structure arranged on the inner wall 8 of the narrow panel member. The key improvement of the structure of the present invention is that the steel flow impact area 11 on the surface of the narrow panel member B is designed for local turbulence enhancement, and the area adopts a plurality of recessed structures 10 and a plurality of protruding structures 16 arranged in an alternating manner on the inner wall of the water slit 9, and the plurality of recessed structures 10 and a plurality of protruding structures 16 on the inner wall of each water slit are concave-convex structures, so as to increase the turbulence intensity of the cooling water, thereby improving the local heat transfer efficiency. The heat transfer structure of the super-large section profiled blank crystallizer described in the present invention has a simple structure, effectively improves the heat transfer efficiency, and effectively meets the heat transfer requirements of super-large section profiled blank continuous casting, thereby improving product processing quality.

[0024] The wide panel member A has a plurality of large holes 6 arranged on the inner wall 17 of the wide panel member near the web 1, a plurality of small holes 7 arranged on the inner wall 17 of the wide panel member A near the R angle 2, a plurality of small holes 7 arranged on the inner wall 17 of the wide panel member A near the large hole 6, a plurality of small holes 7 of a first group arranged on the wide panel member A near the large hole 6, a plurality of small holes 7 of a second group arranged on the first group of small holes 7 of the wide panel member A near the R angle 2, a limiting rod 14 passes through each large hole 6, a spiral threaded portion is arranged on the surface of the limiting rod 14, and a gap 15 is arranged between the limiting rod 14 and the inner wall of the large hole 6. The wide panel member A has a plurality of small holes 7 arranged on the inner wall 17 of the wide panel member A near the inclined surface 3, and a plurality of small holes 7 are also arranged on the inner wall 17 of the wide panel member A near the small holes 7 of the inclined surface 3. In the above structure, when the structure of the wide panel member A is improved, the outer wall of the wide panel member (the outer wall surface of the wide panel member) is a rectangular surface, and the inner wall 5 of the wide panel member (the inner wall surface of the wide panel member) is convex, including a raised web 1 in the middle, symmetrical wings 4 on both sides, an inclined surface 3 connecting the web 1 and the wing 4, a large R angle 2 where the inclined surface 3 intersects with the web 1, and a small R angle 18 where the inclined surface intersects with the wing. Vertical circular holes are drilled along the edge of the inner wall of the wide panel member A, and the water cooling holes of the wide panel member A are designed in a double-layer layout, including large holes 6 and small holes 7. The inner layer of the web 1 is designed with a φ20-25mm circular water-cooling hole, and a φ10-15mm flow-limiting rod is inserted into the circular water hole. There is a gap between the circular water hole and the flow-limiting rod to form a ring-shaped cooling water gap; the flow-limiting rod is made of stainless steel threaded steel bars, and the convex pattern on the surface of the threaded steel bars is used to increase the turbulence intensity of the cooling water, thereby improving the heat transfer efficiency; the outer layer of the web 1 is designed with a φ10-15mm inner diameter water-cooling circular hole to further improve the heat transfer efficiency and heat transfer uniformity. The inner layers of the R angle 2 and the bevel 3 are respectively designed with φ10-15mm inner diameter water-cooling circular holes. The reasonable layout design of the water-cooling holes adapts to the complex heat transfer characteristics of the profiled blank and improves the uniformity of the temperature distribution on the inner wall of the wide panel; the outer layers of the R angle 2 and the bevel 3 are also designed with a small number of φ10-15mm inner diameter water-cooling circular holes to increase the heat transfer efficiency. The wing tip 4 is designed with a single layer of φ10-15mm inner diameter water-cooling circular holes to match the relatively low heat transfer requirements of the wing tip.

[0025] The inner wall 17 of the wide panel member A is provided with a plurality of small holes 7 near the wing tip 4. With the above structure, the small holes 7 can effectively improve the heat transfer efficiency and heat transfer uniformity.

[0026] The diameter φ of the large hole 6 of the inner wall 17 of the wide panel member A near the web 1 is 20 mm to 25 mm; the diameter φ of the flow limiting rod 14 is 10 mm to 15 mm. In the above structure, a φ10-15 mm flow limiting rod is inserted into the circular water hole. A gap is set between the circular water hole and the flow limiting rod to form an annular cooling water gap; the flow limiting rod is made of stainless steel threaded steel bars, and the raised pattern on the surface of the threaded steel bars is used to increase the turbulence intensity of the cooling water, thereby improving the heat transfer efficiency.

[0027] The diameter φ of the small hole 7 on the inner wall 17 of the wide panel member A near the large hole 6 is 10-15 mm, and the diameter φ of the small hole 7 on the inner wall 17 of the wide panel member A near the small hole 7 at the R angle 2 is 10-15 mm. The diameter φ of the small hole 7 on the inner wall 17 of the wide panel member A near the inclined surface 3 is 10-15 mm, and the diameter φ of the small hole 7 on the inner wall 17 of the wide panel member A near the inclined surface 3 is 10-15 mm. The diameter φ of the small hole 7 on the inner wall 17 of the wide panel member A near the wing tip 4 is 10-15 mm. With the above structure, the small holes can improve the heat transfer efficiency and heat transfer uniformity.

[0028] The wide panel member A and the narrow panel member B each include two, and the wide panel member A and the narrow panel member B are both structures made of copper plate material. The wide panel member outer wall 5 of the wide panel member A is flat, and the wide panel member inner wall 17 is convex, and the wide panel member inner wall 17 includes a web 1, an R angle 2, a slope 3 and a wing tip 4, and a small R angle 18.

[0029] The heat transfer structure of the super-large section profiled blank crystallizer of the present invention improves the wide panel member A and the narrow panel member B of the crystallizer respectively. The wide panel member A and the narrow panel member B respectively include two pieces, the narrow panel member B can be a copper plate, the narrow panel member B has a regular rectangular parallelepiped structure, a plurality of water gaps 9 are arranged on the inner wall 8 of the narrow panel member B, and a plurality of recessed structures 10 and a plurality of protruding structures 16 are arranged on the inner wall of each water gap 9 in the steel flow impact area 11 of the narrow panel member B, the narrow panel member B includes the inner wall 8 of the narrow panel member, the upper end 13 and the lower end 12, and the water gap 9 is a groove structure arranged on the inner wall 8 of the narrow panel member. The key improvement of the structure of the present invention is that the steel flow impact area 11 on the surface of the narrow panel member B is designed for local turbulence enhancement. This area adopts a plurality of recessed structures 10 and a plurality of protruding structures 16 arranged in a staggered manner on the inner wall of the water gap 9. The plurality of recessed structures 10 and a plurality of protruding structures 16 on the inner wall of each water gap are concave-convex structures, thereby increasing the turbulence intensity of the cooling water, thereby improving the local heat transfer efficiency. When the structure of the wide panel member A is improved, the outer wall of the wide panel member (the outer wall surface of the wide panel member) is a rectangular surface, and the inner wall 5 of the wide panel member (the inner wall surface of the wide panel member) is convex, including a raised web 1 in the middle, symmetrical wings 4 on both sides, an inclined surface 3 connecting the web 1 and the wing 4, a large R angle 2 where the inclined surface 3 intersects with the web 1, and a small R angle 18 where the inclined surface intersects with the wing. Vertical circular holes are drilled along the edge of the inner wall of the wide panel member A, and the water cooling holes of the wide panel member A are designed in a double-layer layout, including large holes 6 and small holes 7. A circular water-cooling hole is designed in the inner layer of the web 1, and a flow-limiting rod is inserted into the circular water hole. There is a gap between the circular water hole and the flow-limiting rod to form an annular cooling water gap; the flow-limiting rod is made of stainless steel threaded steel bars, and the raised pattern on the surface of the threaded steel bars is used to increase the turbulence intensity of the cooling water, thereby improving the heat transfer efficiency; water-cooling circular holes are designed in the outer layer of the web 1 to further improve the heat transfer efficiency and heat transfer uniformity. The water-cooling circular holes designed in the inner layer of the R angle 2 and the bevel 3 are respectively adapted to the complex heat transfer characteristics of the special-shaped blank through the reasonable layout design of the water-cooling holes to improve the uniformity of the temperature distribution on the inner wall of the wide panel; a small number of water-cooling circular holes are also designed in the outer layer of the R angle 2 and the bevel 3 to increase the heat transfer efficiency. The wing tip 4 is designed with a single layer of water-cooling circular holes to match the relatively low heat transfer requirements of the wing tip.

[0030] The present invention is described above by way of example in conjunction with the accompanying drawings. It is obvious that the specific implementation of the present invention is not limited to the above-mentioned method. As long as various improvements are made using the method concept and technical solution of the present invention, or the concept and technical solution of the present invention are directly applied to other occasions without improvement, they are all within the protection scope of the present invention.

Claims

1. A heat transfer structure for a super-large cross-section profiled blank crystallizer, characterized in that: The crystallizer comprises a wide panel member (A) and a narrow panel member (B), wherein a plurality of water gaps (9) are arranged on the inner wall (8) of the narrow panel member (B), and a plurality of recessed structures (10) and a plurality of protruding structures (16) are arranged on the inner wall of each water gap (9) in the steel flow impact area (11) of the narrow panel member (B). The narrow panel member (B) comprises an inner wall (8), an upper end (13) and a lower end (12), and the water gap (9) is a groove structure arranged on the inner wall (8) of the narrow panel member.

2. The heat transfer structure of the super-large cross-section profiled blank crystallizer according to claim 1 is characterized in that: The wide panel member (A) is provided with a plurality of large holes (6) on the inner wall (17) of the wide panel member near the web (1), and a plurality of small holes (7) on the inner wall (17) of the wide panel member (A) near the R angle (2). The wide panel member (A) is provided with a first group of multiple small holes (7) near the large holes (6), and the wide panel member (A) is further provided with a second group of multiple small holes (7) at the first group of multiple small holes (7) near the R angle (2). A limiting rod (14) passes through each large hole (6), a spiral thread portion is provided on the surface of the limiting rod (14), and a gap (15) is provided between the limiting rod (14) and the inner wall of the large hole (6).

3. The heat transfer structure of the super-large cross-section profiled blank crystallizer according to claim 2 is characterized in that: A plurality of small holes (7) are arranged on the inner wall (17) of the wide panel member (A) near the inclined surface (3), and a second group of multiple small holes (7) are arranged on the inner wall (17) of the wide panel member (A) near the inclined surface (3) in addition to the first group of multiple small holes (7).

4. The heat transfer structure of the super-large cross-section profiled blank crystallizer according to claim 2 or 3, characterized in that: A plurality of small holes (7) are arranged on the inner wall (17) of the wide panel member (A) near the wing tip (4).

5. The heat transfer structure of the super-large cross-section profiled blank crystallizer according to claim 2 or 3, characterized in that: The diameter φ of the large hole (6) on the inner wall (17) of the wide panel member (A) near the web (1) is between 20 mm and 25 mm; the diameter φ of the current limiting rod (14) is between 10 mm and 15 mm.

6. The heat transfer structure of the super-large cross-section profiled blank crystallizer according to claim 2 or 3, characterized in that: The diameter φ of the small hole (7) on the inner wall (17) of the wide panel member (A) near the large hole (6) is 10 to 15 mm, and the diameter φ of the small hole (7) on the inner wall (17) of the wide panel member near the R angle (2) is 10 mm to 15 mm.

7. The heat transfer structure of the super-large cross-section profiled blank crystallizer according to claim 3 is characterized in that: The diameter φ of the small hole (7) on the inner wall (17) of the wide panel member (A) near the inclined surface (3) is between 10 mm and 15 mm, and the diameter φ of the small hole (7) on the inner wall (17) of the wide panel member (A) near the inclined surface (3) is between 10 mm and 15 mm.

8. The heat transfer structure of the super-large cross-section profiled blank crystallizer according to claim 2 is characterized in that: The diameter φ of the small hole (7) on the inner wall (17) of the wide panel member (A) near the wing tip (4) is between 10 mm and 15 mm.

9. The heat transfer structure of the super-large cross-section profiled blank crystallizer according to claim 2 or 3, characterized in that: The wide panel member (A) and the narrow panel member (B) each include two, and the wide panel member (A) and the narrow panel member (B) are both structures made of copper plate material.

10. The heat transfer structure of the super-large cross-section profiled blank crystallizer according to claim 2 or 3, characterized in that: The wide panel member (A) has a flat outer wall (5) and a convex inner wall (17). The wide panel member inner wall (17) includes a web (1), an R angle (2), a slope (3) and a wing tip (4).

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