A design method of a steel ingot holding cap

Abstract

The present application relates to the technical field of steel ingot casting, in particular to a design method of a steel ingot heat preservation cap, comprising S1, designing the thickness of an inner shell; S2, designing the height of the inner shell; S3, calculating the allowable thickness of thermal stress of an outer shell; S4, checking the hoisting mechanical stress of the outer shell. The thickness of the inner shell of the heat preservation cap is determined by thermal stress and static pressure, so that the inner shell of the heat preservation cap can meet the requirements of mechanical strength and thermal stress at the same time, the structure is stable during the forming process of the steel ingot, and good heat preservation effect is achieved, the preparation of high-quality steel ingot is met. Meanwhile, the allowable thickness of thermal stress of the outer shell is calculated, and the hoisting mechanical stress of the outer shell is checked in combination with the allowable stress of the outer shell material at the working temperature, so that the thickness of the outer shell meets the stable use at the working temperature, and the mechanical strength can meet the structural stability requirements in the moving and hoisting process, the service life is prolonged, the heat preservation cap is composed of the inner shell and the outer shell, the use effect of the heat preservation cap is improved, and the preparation of high-quality steel ingot is realized.

Description

Technical Field

[0001] This invention relates to the field of steel ingot casting technology, and specifically to a design method for a steel ingot heat insulation cap. Background Technology

[0002] In the machinery manufacturing industry, a set of containers consisting of a chassis, an ingot mold, and an insulating cap is used to hold molten steel. Molten steel meeting technical requirements is poured into the ingot mold using either top-pouring or bottom-pouring methods to prepare steel ingots. The insulating cap is generally made of a material with a low thermal conductivity to reduce the heat transfer rate in the top area of ​​the ingot, thus delaying the solidification rate of the molten steel in the upper part of the ingot and keeping it in a liquid state for a longer period. This allows for better replenishment of molten steel to the ingot body, overcoming the problem of shrinkage cavities that easily form in the core of the ingot due to the volume shrinkage that occurs when molten steel changes from liquid to solid, leading to solidification defects.

[0003] Traditional thermal caps typically employ a three-layer structure: an outer shell, a middle insulation layer, and an inner shell. The inner shell contacts the molten steel, while the middle insulation layer and the outer shell provide thermal insulation, achieving the desired heat retention.

[0004] For example, a Chinese utility model patent for a heat-insulating cap for casting large steel ingots (publication number CN206305395U) describes a heat-insulating cap base consisting of an inner wall and a base. The inner wall is an upright annular structure, and the base is vertically connected to the lower outer periphery of the inner wall. The outer shell of the heat-insulating cap is an upright steel plate that surrounds the outer periphery of the inner wall of the heat-insulating cap base. The lower end of the steel plate of the outer shell is connected to the upper edge of the outer periphery of the base of the heat-insulating cap base. A cavity is formed between the inner wall of the heat-insulating cap base and the outer shell of the heat-insulating cap, which is closed at the bottom and open at the top, surrounding the outer periphery of the inner wall of the heat-insulating cap base. The cavity is filled with heat-insulating cap refractory insulation material. The thickness of the inner wall is 30mm to 80mm. The outer shell of the heat-insulating cap is welded from a steel plate with a thickness of 20mm to 40mm, and the thickness of the heat-insulating cap refractory insulation material is 50mm to 100mm.

[0005] However, the dimensions of the three-layer structure of existing large vacuum steel ingot insulation caps are generally based on empirically set numerical ranges, without fully considering the mechanical strength and thermal stress requirements of the insulation caps. This results in a short service life and the performance of the insulation caps cannot reach the ideal state, failing to meet the requirements for manufacturing high-quality steel ingots. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of existing technologies, such as the structural design of steel ingot insulation caps not fully considering the mechanical strength and thermal stress requirements of the insulation caps, which affects the service life of the insulation caps and the performance of the insulation caps cannot meet the requirements of high-quality steel ingot manufacturing. This invention provides a design method for steel ingot insulation caps.

[0007] This invention provides a design method for a steel ingot heat insulation cap, comprising the following steps: S1. Design the thickness of the inner shell: Determine the thickness of the inner shell based on the thickness required to withstand thermal stress, the thickness required to withstand the static pressure of molten steel, and the thickness safety margin. S2. Design the height of the inner shell: Determine the height of the inner shell based on the design height of the ingot riser and the ingot shrinkage coefficient; S3. Calculate the allowable thickness for thermal stress of the outer shell; S4. Perform mechanical stress verification for the hoisting of the outer casing: based on the allowable stress of the outer casing material at the operating temperature. Local compressive strength of the outer shell and local bending strength Verification, if < and < Then S3 obtains a thickness that meets the requirements; if ≥ or ≥ Adjust the calculation parameters and repeat steps S3 to S4 until the desired result is achieved.

[0008] This invention discloses a design method for a steel ingot insulation cap. By determining the inner shell thickness based on thermal stress and static pressure, the inner shell of the insulation cap simultaneously meets the requirements for mechanical strength and thermal stress. This ensures structural stability during the steel ingot forming process, providing excellent insulation and meeting the requirements for producing high-quality steel ingots. Furthermore, by calculating the allowable thermal stress thickness of the outer shell and combining it with the allowable stress of the outer shell material at the operating temperature, the mechanical stress of the outer shell during hoisting is checked. This ensures that the outer shell thickness meets the requirements for stable use at the operating temperature, and that the mechanical strength meets the structural stability requirements during movement and hoisting, extending its service life. Combined with the inner shell, this forms an insulation cap, improving its performance and enabling the production of high-quality steel ingots.

[0009] Preferably, the height of the inner shell is greater than the design height of the ingot riser / the ingot shrinkage coefficient.

[0010] Preferably, the steel ingot insulation cap further includes an upper flange plate and a lower flange plate. The upper flange plate is bolted to the top of the inner shell and the outer shell, and the lower flange plate is bolted to the bottom of the inner shell and the outer shell. The thickness of the upper flange plate is 50~150mm, and the thickness of the lower flange plate is 80~150mm.

[0011] Preferably, both the inner shell and the outer shell include a conical section with a taper of 0.05 to 0.15. The lower edge of the conical section of the inner shell is provided with a first brim plate, and the lower edge of the conical section of the outer shell is provided with a second brim plate. The thickness of the first brim plate is 80 to 200 mm, and the thickness of the second brim plate is 50 to 150 mm. Chamfers are provided between the first brim plate and the outer wall of the inner shell, and between the second brim plate and the outer wall of the outer shell, with a chamfer radius of 30 to 100 mm.

[0012] Specifically, the top of the inner shell and the outer shell are connected to the upper flange plate, the bottom of the first cap brim plate and the second cap brim plate are connected to the lower flange plate, the upper flange plate is provided with a number of upper threaded connection holes corresponding to the inner shell and the outer shell respectively, and the upper flange plate is provided with a number of upper lifting lugs symmetrically arranged on the circumferential outer wall, the lower flange plate is provided with a number of lower threaded connection holes corresponding to the first cap brim plate and the second cap brim plate respectively, and the lower flange plate is provided with a number of lower lifting lugs symmetrically arranged on the circumferential outer wall.

[0013] Preferably, a heat insulation layer is formed between the inner shell and the outer shell, and a number of stiffeners are provided in the heat insulation layer. The stiffeners are distributed at intervals along the circumference of the inner shell. One end of the stiffener is welded to the inner shell and the other end abuts against the outer shell. The thickness of the stiffener is 30~60mm and the number of stiffeners is 6~16. The heat insulation layer is a hollow structure or filled with a binding material, and a number of vent holes that penetrate the heat insulation layer are provided on the outer shell.

[0014] Preferably, the thickness of the inner shell satisfies: , In the formula, The thickness of the inner shell is in mm; The thickness of the inner shell required to withstand thermal stress, in mm; The thickness of the inner shell required to withstand the static pressure of molten steel, in mm; This is the safety margin for the thickness of the inner shell material, in mm.

[0015] Preferably, ; ; , In the formula, The coefficient of thermal expansion of the inner shell material is 1 / ℃; is the effective elastic modulus of the inner shell material at the operating temperature, in MPa; The difference between the temperature of the injected molten steel and the initial temperature of the inner shell surface, expressed in °C. R is the average radius of the inner shell, in mm; Density of molten steel, kg / m³ 3 ; The acceleration due to gravity is m / s². 2 ; H is the height of the molten steel inside the heat-insulating cap, in meters; This is the taper deformation coefficient, with a value ranging from 0.1 to 0.8; This is the flange constraint coefficient, with a value ranging from 0.1 to 0.8; The thickness of the inner shell material is a safety margin, in mm; σ 许用-内 denoted as the allowable stress of the inner shell material at the operating temperature, in MPa.

[0016] Preferably, the allowable thickness for thermal stress of the outer casing satisfies: In the formula, The allowable thickness for thermal stress of the outer casing, in mm; The thermal conductivity of the outer casing material; The operating temperature of the inner wall of the casing is ℃; The outer wall of the casing is designed to control the temperature, in °C; The ambient temperature is in °C. The heat exchange coefficient under natural ventilation conditions; The safety factor for the outer casing process is set to 1.5 to 5.

[0017] Preferably, the allowable stress of the inner shell material at the operating temperature is 20% to 30% of the allowable stress of the inner shell material at room temperature; the allowable stress of the outer shell material at the operating temperature is 50% to 80% of the allowable stress of the outer shell material at room temperature; if ≥ or ≥ Adjust the safety factor of the outer shell process and recalculate the allowable thickness of the outer shell for thermal stress.

[0018] Preferably, the outer wall of the inner shell is provided with at least two internal lifting lugs symmetrically, and the outer wall of the outer shell is provided with at least two main lifting lugs symmetrically, and the local compressive strength of the outer shell is... and local bending strength The verification points are all located at the main lifting lug.

[0019] Preferably, local compressive strength satisfy: ; Local bending strength satisfy: ; In the formula, F 动 =F 静 *K, F 动 For the overall hoisting dynamic load of the thermal cap, N; F静 The static load of the insulation cap is N; K is the dynamic load factor for hoisting, with a value of 1~1.5. B is the contact width between the main lifting lug and the outer shell, in mm; L is the effective support length of the main lifting lug, in mm.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention provides a design method for a steel ingot insulation cap. By determining the inner shell thickness of the insulation cap based on thermal stress and static pressure, the inner shell of the insulation cap can simultaneously meet the requirements of mechanical strength and thermal stress, ensuring structural stability during the steel ingot forming process and achieving a good insulation effect, thus meeting the requirements for the preparation of high-quality steel ingots. 2. This invention provides a design method for a steel ingot insulation cap. By calculating the allowable thickness of the outer shell for thermal stress and combining it with the allowable stress of the outer shell material at the working temperature, the mechanical stress of the outer shell for hoisting is checked. This ensures that the outer shell thickness meets the requirements for stable use at the working temperature and that the mechanical strength meets the structural stability requirements during mobile hoisting, thus extending the service life. When combined with the inner shell, it forms an insulation cap, improving the performance of the insulation cap and achieving the preparation of high-quality steel ingots. Attached Figure Description

[0021] Figure 1 This is a flowchart illustrating the design method of a steel ingot heat preservation cap according to Example 1.

[0022] Figure 2 This is a schematic diagram of the structure of the steel ingot heat preservation cap described in Example 1.

[0023] Figure 3 This is a schematic cross-sectional view of the inner shell described in Example 1.

[0024] Figure 4 This is a top view of the inner shell described in Example 1.

[0025] Figure 5 This is a half-sectional view of the outer casing described in Example 1.

[0026] Marked in the image: 1-Inner shell, 11-First brim plate, 12-Inner lug, 2-Outer shell, 21-Second brim plate, 22-Main hanging lug, 23-Ventilation hole 3-Upper flange plate, 31-Upper lifting lug, 32-Upper threaded connection hole, 4-Lower flange plate, 41-Lower lifting lug, 42-Lower threaded connection hole 5-rib plate, 6-Insulation layer. Detailed Implementation

[0027] The present invention will now be described in further detail with reference to specific embodiments. However, this should not be construed as limiting the scope of the present invention to the following embodiments; all technologies implemented based on the content of the present invention fall within the scope of the present invention.

[0028] Unless otherwise specified, the terms "upper," "lower," "left," "right," "center," "inner," and "outer," etc., used in the description of specific embodiments of the present invention to indicate orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings, or the orientation or positional relationship in which the product / equipment / device is usually placed during use. These terms are merely for the purpose of facilitating the description of the present invention or simplifying the description in specific embodiments, and for enabling those skilled in the art to quickly understand the solution, and do not indicate or imply that a particular device / component / element must have a specific orientation, or be constructed and operated in a specific positional relationship. Therefore, they should not be construed as limitations on the present invention.

[0029] Furthermore, the use of terms such as "horizontal," "vertical," "suspended," "parallel," and "coaxial" does not imply that the corresponding device / component / element must be absolutely horizontal, vertical, suspended, parallel, or coaxial. Slight tilt or deviation is permissible, as long as it does not affect the normal function of the relevant component. For example, "horizontal" simply means that its direction is more horizontal relative to "vertical," not that the structure must be perfectly horizontal; a slight tilt is acceptable. "Coaxial" means that two components are arranged as coaxially as possible, allowing them to move coaxially or approximately coaxially when their relative positions change. Alternatively, it can be simplified to mean that the corresponding device / component / element, when arranged in "horizontal," "vertical," "suspended," "parallel," or "coaxial" directions, can have an error / deviation of ±10% relative to the corresponding direction, more preferably within ±8%, more preferably within ±6%, more preferably within ±5%, and more preferably within ±4%. For example, the deviation in the "coaxial" direction is controlled within 0.2-1mm, preferably within 0.2-0.5mm. As long as the corresponding device / component / element is within the error / deviation range, it can still achieve its function in the solution of the present invention.

[0030] Furthermore, the use of terms such as "first," "second," and "third" in terminology is merely for distinguishing descriptions of identical or similar components and should not be interpreted as emphasizing or implying the relative importance of a particular component.

[0031] Furthermore, in the description of the embodiments of the present invention, "several", "more than", and "a number of" represent at least two. The number can be any number, such as two, three, four, five, six, seven, eight, or nine, and can even exceed nine.

[0032] Furthermore, in the description of the technical solution of this invention, unless otherwise explicitly specified / limited / restricted, the terms "set up," "install," "connect," "link," "provided with," "laid out," and "arranged" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to connection methods commonly used in the art, such as welding, riveting, bolting, and threaded connections. Such connections can be mechanical, electrical, or communication connections; they can be direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication between two components.

[0033] Example 1 like Figure 1 As shown, a design method for a steel ingot heat insulation cap includes the following steps: S1. Design the thickness of the inner shell: Determine the thickness of the inner shell based on the thickness required to withstand thermal stress, the thickness required to withstand the static pressure of molten steel, and the thickness safety margin.

[0034] S1 is used to design the thickness of the inner shell based on the thermal stress and mechanical strength of the inner shell. The design of the inner shell thickness can be determined comprehensively based on thermal stress, static pressure and solidification chill layer, so that the inner shell can simultaneously meet the requirements of mechanical strength and thermal stress. Considering that the existence of solidification chill layer is beneficial to improving the working safety of the heat insulation cap, S1 can ignore the existence of solidification chill layer when designing the thickness of the inner shell.

[0035] In one or more embodiments, the thickness of the inner shell satisfies: In the formula, The thickness of the inner shell is in mm; The thickness of the inner shell required to withstand thermal stress, in mm; The thickness of the inner shell required to withstand the hydrostatic pressure of molten steel, in mm. Much smaller than hour It can be ignored; This is the safety margin for the thickness of the inner shell material, in mm.

[0036] In an optional embodiment, the inner shell can be integrally cast from cast iron, and the thickness safety margin of the inner shell material can be considered as a process safety margin for casting and wear. Using integrally cast iron for the inner shell, compared to existing methods that use refractory materials such as refractory bricks as the inner shell's insulation cap, avoids the problem of molten steel contamination caused by contact between the inner shell and the molten steel, thereby improving the purity of the molten steel and thus the purity of the steel ingot, ultimately improving the quality of the forgings made from the steel ingot.

[0037] In this embodiment, the maximum static pressure of the inner shell is calculated based on the limit of the riser molten steel height. The limit of the riser molten steel height is set to 1m. The required thickness of the inner shell to withstand thermal stress and the required thickness to withstand the static pressure of the molten steel are determined by considering the inner shell's operating temperature, material properties, and steel density. Specifically: ; ; , In the formula, The coefficient of thermal expansion of the inner shell material is 1 / ℃; is the effective elastic modulus of the inner shell material at the operating temperature, in MPa; The difference between the temperature of the injected molten steel and the initial temperature of the inner shell surface, expressed in °C. R is the average radius of the inner shell, in mm; Density of molten steel, kg / m³ 3 ; The acceleration due to gravity is m / s². 2 The value is 9.8 m / s 2 ; H is the height of the molten steel inside the heat-insulating cap, in meters; This is the taper deformation coefficient, with a value ranging from 0.1 to 0.8; This is the flange constraint coefficient, with a value ranging from 0.1 to 0.8; The thickness of the inner shell material is a safety margin, in mm; σ 许用-内 denoted as the allowable stress of the inner shell material at the operating temperature, in MPa.

[0038] In an optional embodiment, in the steel molten casting environment, the effective elastic modulus of the inner shell material at the working temperature can be taken as 20%-30% of the room temperature elastic modulus of the inner shell material, and the allowable stress σ of the inner shell material at the working temperature... 许用-内 The value can be 20%-30% of the allowable stress of the inner shell material at room temperature; in a mold-cooled environment, the effective elastic modulus of the outer shell material at the working temperature can be taken as 80% of the elastic modulus of the outer shell material at room temperature.

[0039] In an optional implementation, the average radius R of the inner shell is equal to (radius of the upper edge of the inner shell + radius of the lower edge of the inner shell) / 2.

[0040] S2. Design the height of the inner shell: Determine the height of the inner shell based on the design height of the ingot riser and the ingot shrinkage coefficient.

[0041] S2 is used to design the height of the inner shell based on the height of the molten steel poured into the heat insulation cap and the shrinkage coefficient of the steel ingot, so that the heat insulation cap meets the requirements of the riser pouring height.

[0042] In one or more embodiments, the height of the inner shell is greater than the design height of the ingot riser divided by the ingot shrinkage coefficient. This ensures that the height of the inner shell meets the safety requirements during the ingot casting and solidification process.

[0043] In an optional implementation, the shrinkage coefficient η of the steel ingot can be 0.95 to 0.97.

[0044] S3. Calculate the allowable thickness for thermal stress of the outer shell.

[0045] S3 is used to calculate and determine the allowable thermal stress thickness of the shell based on parameters such as shell material, operating temperature, and shell process verification safety factor. This ensures that the shell thickness can guarantee that the thermal stress caused by temperature difference does not exceed the allowable stress of the material at that temperature during operation, thus avoiding cracking or plastic deformation caused by thermal stress and ensuring that the shell thickness meets the thermal stress requirements.

[0046] In one or more embodiments, the allowable thickness for thermal stress of the housing satisfies: , In the formula, The allowable thickness for thermal stress of the outer casing, in mm; The thermal conductivity of the outer casing material; The operating temperature of the inner wall of the casing is ℃; The outer wall of the casing is designed to control the temperature, in °C; The ambient temperature is in °C. The heat exchange coefficient under natural ventilation conditions; The safety factor for the outer casing process is set to 1.5 to 5.

[0047] In an optional embodiment, the operating temperature of the inner wall of the outer casing is the interface temperature between the insulation layer and the outer casing, i.e., the temperature of the inner wall of the outer casing.

[0048] In an optional implementation, the heat exchange coefficient under natural ventilation conditions can be taken as 12 W / (m²). K).

[0049] S4. Perform mechanical stress verification for the hoisting of the outer casing: based on the allowable stress of the outer casing material at the operating temperature. Local compressive strength of the outer shell and local bending strength Verification, if < and < Then S3 obtains a thickness that meets the requirements; if ≥ or ≥ Adjust the calculation parameters and repeat steps S3 to S4 until the desired result is achieved.

[0050] S4 is used to check the mechanical stress of the outer shell for lifting based on the allowable thickness of thermal stress obtained from S3, so that the outer shell meets both mechanical strength and thermal stress requirements, can be lifted and moved stably, and can improve the insulation effect when combined with the inner shell, which helps to achieve the preparation of high-quality steel ingots.

[0051] In one or more embodiments, at least two internal lifting lugs are symmetrically arranged on the outer wall of the inner shell, and at least two main lifting lugs are symmetrically arranged on the outer wall of the outer shell. Considering that the main lifting lugs bear the greatest stress and are the weakest points in the structure during use, the local compressive strength of the outer shell is determined. and local bending strength The verification points are all located at the main lifting lug.

[0052] In one or more embodiments, the allowable stress of the housing material at the operating temperature is taken as 50% to 80% of the allowable stress of the housing material at room temperature.

[0053] In an optional implementation, local compressive strength satisfy: ; Local bending strength satisfy: ; In the formula, F 动 =F 静 *K, F 动 For the overall hoisting dynamic load of the thermal cap, N; F 静 The static load of the insulation cap is N; K is the dynamic load factor for hoisting, with a value of 1.0~1.5. B is the contact width between the main lug and the outer shell of the thermal cap, in mm; L is the effective support length of the main lifting lug, in mm.

[0054] In an optional embodiment, the overall static load of the heat insulation cap can be the total weight of the outer shell, inner shell, heat insulation layer binding material, upper flange plate, and lower flange plate, F. 静 =(m 外 +m 内 +m 隔热 +m 上法兰 +m 下法兰 )*g; m 外 The mass of the outer casing is in kg; m 内 The mass of the inner shell is in kg; m 隔热 For the mass of the briquetted material, kg; m 上法兰 The mass of the upper flange plate is in kg; m 下法兰 The mass of the lower flange plate is in kg; g is the acceleration due to gravity, 9.8 m / s².

[0055] This embodiment presents a design method for a steel ingot heat insulation cap, such as... Figures 2-5 Taking the circular heat-insulating cap shown as an example, the steel ingot heat-insulating cap includes an inner shell 1, an outer shell 2, an upper flange plate 3, and a lower flange plate 4. A heat insulation layer 6 is formed between the inner shell 1 and the outer shell 2. Several reinforcing ribs 5 are arranged within the heat insulation layer 6, spaced apart circumferentially along the inner shell 1. One end of each reinforcing rib 5 is welded to the inner shell 1, and the other end abuts against the outer shell 2. Both the inner shell 1 and the outer shell 2 include a conical section. A first brim plate 11 is provided along the lower edge of the conical section of the inner shell 1, and a second brim plate 21 is provided along the lower edge of the conical section of the outer shell 2. The first brim plate 11 is connected to the outer shell 2 of the inner shell 1. Chamfers are provided between the wall connections and between the second brim plate 21 and the outer wall of the outer shell 2. The cross-sectional contour shape and size of the outer shell 2 and the inner shell 1 are the same. The top of the inner shell 1 and the outer shell 2 are connected to the upper flange plate 3. The bottom of the first brim plate 11 and the second brim plate 21 are connected to the lower flange plate 4. At least two inner lifting lugs 12 are provided axially symmetrically on the outer wall of the inner shell 1. At least two main lifting lugs 22 are provided axially symmetrically on the outer wall of the outer shell 2. The main lifting lugs 22 can be integrally formed with the outer shell 2. The inner lifting lugs 12 can be integrally formed with the inner shell 1. The arrangement of the first brim plate 11 and the second brim plate 21 enhances the combined installation strength of the inner shell 1 and the lower flange plate 4, as well as the combined installation strength of the outer shell 2 and the lower flange plate 4. This improves the overall structural strength of the heat-insulating cap, enhancing its stability and safety. Furthermore, the chamfered design facilitates the integral casting of the inner shell 1 and the outer shell 2, reducing stress concentration at the chamfered area and improving the forming quality of the inner shell 1 and the outer shell 2. Simultaneously, the first brim plate 11 creates sufficient heat exchange space between the inner shell 1 and the outer shell 2, reducing... The heat transferred from the molten steel inside the heat-insulating cap to the outer shell 2 enables the heat-insulating cap to be used safely and effectively. The first brim plate 11 provides an installation position for the stable setting and safe use of the stiffening plate 5. Since the setting of the first brim plate 11 is conducive to improving the structural strength of the inner shell 1, the junction between the conical part of the inner shell 1 and the first brim plate 11 is the area with the maximum static pressure. When calculating the static pressure of the molten steel borne by the inner shell 1, the thickness of the inner shell 1 can be determined by calculating the static pressure at this point, or the maximum static pressure borne by the inner shell 1 can be calculated by using the limit of the height of the molten steel at the commonly used riser.

[0056] In one or more embodiments, threaded holes are provided on the top and bottom surfaces of the inner shell 1 and the outer shell 2, so that the upper flange plate 3 is connected to the top of the inner shell 1 and the outer shell 2 by bolts, and the lower flange plate 4 is connected to the first cap brim plate 11 and the second cap brim plate 21 by bolts, so that the inner shell 1, the outer shell 2, the upper flange plate 3 and the lower flange plate 4 are assembled into a heat-insulating cap, which can be moved as a whole and is convenient to use.

[0057] In an optional embodiment, the length of the first brim plate 11 should meet the opening requirements of the threaded hole and the lifting requirements of the inner lifting lug 12 on the inner shell 1. The thickness of the first brim plate 11 can be 80~200mm. The length of the inner lifting lug 12 can be set to be less than the extension length of the first brim plate 11 to avoid positional interference with the outer shell 2, as long as the lifting conditions are met, so as to facilitate the lifting and moving of the inner shell 1.

[0058] In an optional embodiment, the length of the second brim plate 21 meets the requirements for the threaded hole opening, while the safety factor for stress concentration should be considered to ensure the overall safe lifting and moving of the heat insulation cap. The thickness of the second brim plate 21 can be 50~150mm.

[0059] In an optional embodiment, the connection between the first brim plate 11 and the outer wall of the inner shell 1, and the connection between the second brim plate 21 and the outer wall of the outer shell 2, are both set with rounded chamfers, and the chamfer radius r can be 30~100mm.

[0060] In an optional embodiment, both the inner and outer walls of the inner shell 1 are tapered, and the tapering value can be 0.05 to 0.15.

[0061] In an optional embodiment, when the inner diameter of the upper edge of the inner shell 1 of the heat insulation cap is ≤800mm, the taper value is 0.05~0.08; when 800mm < inner diameter of the upper edge of the inner shell 1 of the heat insulation cap is ≤1600mm, the taper value is 0.08~0.12; when the inner diameter of the upper edge of the inner shell 1 of the heat insulation cap is >1600mm, the taper value is 0.12~0.15.

[0062] In an optional embodiment, the thickness of the stiffening plate 5 is 30~60mm, and the number of stiffening plates 5 is 6~16.

[0063] In this embodiment, the stiffener 5 is parallelogram-shaped, and the height of the stiffener 5 is the same as the height of the conical section of the inner shell 1. The stiffener 5 is made of steel plate, and an assembly gap of no more than 5mm can be provided between the stiffener 5 and the outer shell 2.

[0064] In this embodiment, when the inner diameter of the upper edge of the inner shell 1 of the heat insulation cap is ≤800mm, the number of ribs 5 can be 6 to 8; when 800mm < inner diameter of the upper edge of the inner shell 1 of the heat insulation cap is ≤1600mm, the number of ribs 5 can be 8 to 12; when the inner diameter of the upper edge of the inner shell 1 of the heat insulation cap is >1600mm, the number of ribs 5 can be 12 to 16.

[0065] In one or more embodiments, the heat insulation layer 6 is a hollow structure or filled with a knotting material. The heat insulation layer 6 provides good heat insulation, and when filled with knotting material, it can also support the inner shell 1 and the outer shell 2, improving the structural stability of the heat insulation cap during use.

[0066] In an optional embodiment, when the inner diameter of the lower edge of the inner shell 1 of the heat insulation cap is ≤2000mm, the heat insulation layer 6 can be set as a hollow structure; when the inner diameter of the lower edge of the inner shell 1 of the heat insulation cap is >2000mm, the heat insulation layer 6 can be filled with a bridging material and bridging it into shape. The bridging material can be prepared by refractory aggregates / clinker such as quartz sand, high alumina bauxite, and mullite.

[0067] In one or more embodiments, when the height of the conical section of the outer shell 2 is ≥1000mm, a first main lifting lug 22 can be set at the upper 1 / 3 position of the height of the conical section of the outer shell 2, and a second main lifting lug 22 can be set at the lower 1 / 3 position. When the height of the conical section of the outer shell 2 is <1000mm, the first main lifting lug 22 and the second main lifting lug 22 can overlap, and only a pair of axially symmetrical main lifting lugs 22 are set to stabilize the center of gravity of the outer shell 2 during the lifting process and ensure the stable lifting and movement of the heat insulation cap.

[0068] In one or more embodiments, a plurality of vent holes 23 are also provided on the outer shell 2, and the vent holes 23 are in communication with the heat insulation layer 6.

[0069] In an optional embodiment, the vent holes 23 can be inclined with the inner side lower than the outer side, and the diameter of the vent holes 23 is φ10~φ30mm, and the number is not less than 6.

[0070] In this embodiment, the vent holes 23 are randomly distributed on the side wall of the outer shell 2. The inclination angle of the vent holes 23 can be set to 45°, with the inner side lower and the outer side higher, which is conducive to the upward flow of air and improves the forming quality of steel ingots.

[0071] In one or more embodiments, the thickness of the upper flange plate 3 is 50~150mm, and the thickness of the lower flange plate 4 is 80~150mm. The upper flange plate 3 has several upper threaded connection holes 32 corresponding to the inner shell 1 and the outer shell 2, respectively. Several upper lifting lugs 31 are symmetrically arranged on the circumferential outer wall of the upper flange plate 3. The lower flange plate 4 has several lower threaded connection holes 42 corresponding to the first cap plate 11 and the second cap plate 21, respectively. Several lower lifting lugs 41 are symmetrically arranged on the circumferential outer wall of the lower flange plate 4. The upper threaded connection holes 32 of the upper flange plate 3 corresponding to the inner shell 1 and the upper threaded connection holes 32 of the upper flange plate 3 corresponding to the outer shell 2 can be designed to be staggered according to the actual situation and the overall stress state. The design concept of the lower threaded connection holes 42 on the lower flange plate 4 is the same.

[0072] In an optional embodiment, the upper flange plate 3 can be made of cast steel or steel plate. When the inner diameter of the lower edge of the outer shell 2 is ≤2000mm, the thickness of the upper flange plate 3 is taken as the lower limit of the range. When the inner diameter of the lower edge of the outer shell 2 is >2000mm, the thickness of the upper flange plate 3 is taken as the upper limit of the range.

[0073] In an optional embodiment, the upper flange plate 3 is provided with 6 to 12 threaded connection holes 32 corresponding to the inner shell 1 and the outer shell 2 respectively.

[0074] In this embodiment, when the diameter of the upper flange plate 3 is ≤800mm, 6 to 8 threaded connection holes 32 are respectively arranged on the upper flange plate 3 corresponding to the inner shell 1 and the outer shell 2; when the diameter of the upper flange plate 3 is ≤1600mm and 800mm < 1600mm, 8 to 10 threaded connection holes 32 are respectively arranged on the upper flange plate 3 corresponding to the inner shell 1 and the outer shell 2; when the diameter of the upper flange plate is >1600mm, 10 to 12 threaded connection holes 32 are respectively arranged on the upper flange plate 3 corresponding to the inner shell 1 and the outer shell 2; the threaded connection holes 32 are through holes of M10 to M30.

[0075] In this embodiment, four upper lifting lugs 31 are evenly distributed on the outer circumferential side of the upper flange plate 3.

[0076] In an optional embodiment, the lower flange plate 4 can be made of cast iron, cast steel or steel plate. The number and size of the lower threaded connection holes 42 and the lower lifting lugs 41 on the lower flange plate 4 are the same as those on the upper flange plate 3. The lower threaded connection holes 42 of the lower flange plate 4 corresponding to the first cap plate 11 and the second cap plate 21 can be designed to be misaligned according to the actual situation and the overall stress state.

[0077] Example 2 like Figures 2-5This embodiment uses a circular steel ingot insulation cap with an inner diameter of 1500mm as an example. The steel ingot insulation cap consists of an inner shell 1, an outer shell 2, an upper flange plate 3, and a lower flange plate 4. A first brim plate 11 is provided at the lower edge of the inner shell 1, and a second brim plate 21 is provided at the lower edge of the outer shell 2. The upper flange plate 3 is connected to the top of the inner shell 1 and the outer shell 2, and the lower flange plate 4 is connected to the bottom of the first brim plate 11 and the second brim plate 21. A heat insulation layer 6 is formed between the inner shell 1 and the outer shell 2. Several stiffening plates 5 connected to the outer wall of the inner shell 1 are provided in the heat insulation layer 6. Both the inner shell 1 and the outer shell 2 are integrally cast from cast iron. The material properties of the inner shell 1 and the outer shell 2 are shown in Table 1 below. Table 1 Material Properties

[0078] Step 1: Design the thickness of the inner shell: The inner shell has an upper inner diameter of 1500mm, a taper of 0.13, and a lower inner diameter of 1650mm. The inner shell material thickness has a safety margin of 15mm. The height H of the molten steel inside the insulation cap is considered to be 1m. The effective elastic modulus at working temperature is determined as 20% of the material's room temperature elastic modulus. The taper deformation coefficient is taken as 0.3, the flange constraint coefficient as 0.2, and the molten steel density... The allowable stress σ of the inner shell material at the operating temperature is taken as 7200 kg / m³. 许用-内 The value is taken as 20% of the allowable stress of the inner shell material at room temperature.

[0079] Calculate the thickness of the inner shell based on the material properties. for:

[0080] Substitute the data into the calculation: = =204mm, take the integer with a last digit of 0 or 5, and the design value is 205mm.

[0081] Step 2: Design the height of the inner shell: The height of the inner shell is designed to be 1500mm.

[0082] Step 3: Calculate the allowable thickness for thermal stress on the outer casing: The operating temperature of the inner wall of the outer casing is 1000℃, the design control temperature of the outer wall is selected as 300℃, the ambient temperature is 25℃, the heat exchange coefficient under natural ventilation conditions is selected as 12, and the safety factor for the casing process check is selected as 2.5. Based on the material properties, the allowable thickness for thermal stress of the outer casing is calculated. for:

[0083] Substitute the data into the calculation:

[0084] Round up to the nearest integer with a decimal of 0 or 5 to obtain the allowable thermal stress thickness of the outer shell. The value is 20mm.

[0085] Furthermore, determine the parameters of other auxiliary structural features on the inner and outer shells: If the thickness of the first brim plate is selected as 150mm, then the height of the conical section of the inner shell is 1350mm, and the heights of the outer shell and the inner shell are the same.

[0086] The width of both the first and second brims is designed to be 80mm.

[0087] The number of stiffeners is selected as 10, and the thickness is selected as 30mm.

[0088] The insulation layer is designed as a hollow structure.

[0089] The upper flange plate is made of 60mm thick steel plate, with 6 upper threaded connection holes distributed in the inner shell and 6 upper threaded connection holes distributed in the outer shell, and the hole diameter is M10; the lower flange plate is made of 80mm thick cast iron plate, with 8 lower threaded connection holes distributed in the inner shell and 8 lower threaded connection holes distributed in the outer shell.

[0090] Upper flange width = inner shell thickness + outer shell thickness + first cap plate length = 205 + 20 + 80 = 305mm Lower flange width = inner shell thickness + outer shell thickness + first brim plate length + second brim plate length = 205 + 20 + 80 + 80 = 385mm It should be noted that the widths of the upper and lower flanges are both the single-sided projection widths of the longitudinal section of the centerline of the insulation cap. Based on the calculated widths of the upper and lower flanges, and combined with the material properties, the weights of the upper and lower flanges can be obtained respectively. Combined with the dimensions of the inner and outer shells, the total weight of the inner shell, outer shell, upper flange, and lower flange can be obtained, which is the overall static load of the insulation cap.

[0091] Step 4: Perform mechanical stress verification for the outer casing during hoisting. First, calculate the overall static load F of the heat insulation cap. 静 for: F 静 =(m 外 +m 内 +m 隔热 +m 上法兰 +m 下法兰 )*g=(3.8+9.3+0.3+0.37+0.69) 9.8 = 141987 N; Two main lifting lugs are symmetrically arranged on the upper part of the shell. The static load borne by a single main lifting lug is: 141987 / 2=70994N; Selecting a lifting dynamic load factor of 1.2, the dynamic load at a single main lifting lug is calculated as: F 动 =F 静 1.2 = 85192 N; Then, the contact width B between the main lifting lug and the outer shell is designed to be 300mm, and the effective support length of the main lifting lug is 150mm. The local compressive strength is calculated. for: =85192 / (300) 20) = 14.2 MPa; Furthermore, the outer casing is integrally cast from cast iron. The allowable stress of the casing material at the operating temperature is selected as 60% of the allowable stress of the casing material at room temperature. The allowable stress of the casing at the operating temperature is calculated. for: =250Mpa 60% = 150 MPa < The thickness meets the design requirements; Furthermore, calculate the local bending strength. for:

[0092] > The bending check result was not satisfactory, indicating that the calculated allowable thickness of the shell for thermal stress did not meet the design requirements.

[0093] The safety factor for the outer casing process verification was adjusted to 3.5, and the allowable thickness for thermal stress of the outer casing was recalculated. for: ; Substitute the data into the calculation: mm; take the value 30mm; combine the material properties to obtain the outer shell weight again and calculate the overall static load F of the heat insulation cap. 静 for: F 静 = (4.2 + 9.3 + 0.3 + 0.37 + 0.69) 9.8 = 146412 N; The static load borne by a single main lifting lug is calculated as: 141987 / 2 = 73206 N; Single main lifting lug dynamic load For: F 动 =F 静 1.2 = 87847.7 N; Local compressive strength check of the outer shell: =85192 / (300*20)=14.64Mpa; Allowable stress of the housing at operating temperature for: =250Mpa * 60% = 150Mpa; < It meets the design requirements.

[0094] Local bending check of the outer shell: ; < The result meets the design requirements, indicating that the allowable thickness of the shell for thermal stress obtained from the calculation meets the design requirements.

[0095] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A design method for a steel ingot heat-insulating cap, characterized in that, Includes the following steps: S1. Design the thickness of the inner shell: Determine the thickness of the inner shell based on the thickness required to withstand thermal stress, the thickness required to withstand the static pressure of molten steel, and the thickness safety margin. S2. Design the height of the inner shell: Determine the height of the inner shell based on the design height of the ingot riser and the ingot shrinkage coefficient; S3. Calculate the allowable thickness for thermal stress of the outer shell; S4. Perform mechanical stress verification for the hoisting of the outer casing: based on the allowable stress of the outer casing material at the operating temperature. Local compressive strength of the outer shell and local bending strength Verification, if < and < Then S3 obtains a thickness that meets the requirements; if ≥ or ≥ Adjust the calculation parameters and repeat steps S3 to S4 until the desired result is achieved.

2. The design method of a steel ingot heat preservation cap according to claim 1, characterized in that, The height of the inner shell is greater than the design height of the ingot riser / the shrinkage coefficient of the ingot.

3. The design method of a steel ingot heat-insulating cap according to claim 1, characterized in that, The steel ingot insulation cap also includes an upper flange plate and a lower flange plate. The upper flange plate is bolted to the top of the inner shell and the outer shell, and the lower flange plate is bolted to the bottom of the inner shell and the outer shell. The thickness of the upper flange plate is 50~150mm, and the thickness of the lower flange plate is 80~150mm.

4. The design method of a steel ingot heat preservation cap according to claim 1, characterized in that, Both the inner shell and the outer shell include a conical section with a taper of 0.05 to 0.

15. The lower edge of the conical section of the inner shell is provided with a first brim, and the lower edge of the conical section of the outer shell is provided with a second brim. The thickness of the first brim is 80 to 200 mm, and the thickness of the second brim is 50 to 150 mm. Chamfers are provided between the first brim and the outer wall of the inner shell, and between the second brim and the outer wall of the outer shell, with a chamfer radius of 30 to 100 mm.

5. The design method of a steel ingot heat preservation cap according to claim 1, characterized in that, A heat insulation layer is formed between the inner shell and the outer shell. Several stiffeners are provided in the heat insulation layer. The stiffeners are distributed at intervals along the circumference of the inner shell. One end of the stiffener is welded to the inner shell and the other end abuts against the outer shell. The thickness of the stiffener is 30~60mm and the number of stiffeners is 6~16. The heat insulation layer is a hollow structure or filled with knotting material. Several vent holes that penetrate the heat insulation layer are provided on the outer shell.

6. The design method of a steel ingot heat preservation cap according to claim 1, characterized in that, The thickness of the inner shell satisfies: In the formula, The thickness of the inner shell; The thickness of the inner shell required to withstand thermal stress, in mm; The thickness of the inner shell required to withstand the static pressure of molten steel, in mm; The thickness of the inner shell material is a safety margin, in mm; ； ； In the formula, The coefficient of thermal expansion of the inner shell material is 1 / ℃; is the effective elastic modulus of the inner shell material at the operating temperature, in MPa; The difference between the temperature of the injected molten steel and the initial temperature of the inner shell surface, expressed in °C. R is the average radius of the inner shell, in mm; Density of molten steel, kg / m³ 3 ; The acceleration due to gravity is m / s². 2 ; H is the height of the molten steel inside the heat-insulating cap, in meters; This is the taper deformation coefficient, with a value ranging from 0.1 to 0.8; This is the flange constraint coefficient, with a value ranging from 0.1 to 0.8; The thickness of the inner shell material is a safety margin, in mm; σ 许用-内 denoted as the allowable stress of the inner shell material at the operating temperature, in MPa.

7. The design method of a steel ingot heat preservation cap according to claim 6, characterized in that, The allowable thickness for thermal stress of the outer casing meets the following requirements: In the formula, The allowable thickness for thermal stress of the outer casing, in mm; The thermal conductivity of the outer casing material; The operating temperature of the inner wall of the casing is ℃; The outer wall of the casing is designed to control the temperature, in °C; The ambient temperature is in °C. The heat exchange coefficient under natural ventilation conditions; The safety factor for the outer casing process is set to 1.5 to 5.

8. The design method of a steel ingot heat-insulating cap according to claim 7, characterized in that, The allowable stress of the inner shell material at operating temperature is taken as 20%~30% of the allowable stress of the inner shell material at room temperature; the allowable stress of the outer shell material at operating temperature is taken as 50%~80% of the allowable stress of the outer shell material at room temperature; if ≥ or ≥ Adjust the safety factor of the outer shell process and recalculate the allowable thickness of the outer shell for thermal stress.

9. A design method for a steel ingot heat-insulating cap according to any one of claims 1-8, characterized in that, The inner shell has at least two internal lifting lugs symmetrically arranged on its outer wall, and the outer shell has at least two main lifting lugs symmetrically arranged on its outer wall. The local compressive strength of the outer shell... and local bending strength The verification points are all located at the main lifting lug.

10. The design method of a steel ingot heat-insulating cap according to claim 9, characterized in that, Local compressive strength satisfy: ; Local bending strength satisfy: ; In the formula, F 动 =F 静 *K, F 动 For the overall hoisting dynamic load of the thermal cap, N; F 静 The static load of the insulation cap is N; K is the dynamic load factor for hoisting, with a value of 1~1.

5. B is the contact width between the main lifting lug and the outer shell, in mm; L is the effective support length of the main lifting lug, in mm.

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