A dynamic solidification system and method for a steel ingot

Abstract

The present application relates to the technical field of metallurgy, and discloses a steel ingot dynamic solidification system and a solidification method, wherein the dynamic solidification system comprises a pouring system, a vibration excitation device and a controller, the pouring system comprises a pouring base, multiple sets of steel ingot molds and a pouring pipe, the multiple sets of steel ingot molds are fixed on the top of the pouring base, and the pouring pipe is in communication with the multiple sets of steel ingot molds; the vibration excitation device is a non-insertion type vibration excitation device, the vibration output end of the vibration excitation device is connected with the pouring base; and the controller is used for adjusting the vibration excitation frequency of the vibration excitation device according to the overall mass of the vibration receiver composed of the pouring base, the pouring pipe and the multiple sets of steel ingot molds, so that the vibration excitation frequency of the vibration excitation device is equal to the natural frequency of the vibration receiver to realize the resonance of the pouring system. The present application directly applies the resonance vibration excitation force to the pouring base by using the vibration excitation device, realizes multi-mode resonance, improves the production efficiency, does not invade the molten steel, fundamentally avoids the burning of the vibration rod and the risk of the falling and remaining of the attached oxide skin and coating, and guarantees the purity of the steel ingot.

Description

Technical Field

[0001] This invention relates to the field of metallurgical technology, specifically to a dynamic solidification system and solidification method for steel ingots. Background Technology

[0002] In the metallurgical and forging industries, the cooling and solidification process of molten steel after being poured into the ingot mold is conventionally a static solidification process without external force. During this process, the high-temperature metal comes into contact with the ingot mold and is rapidly cooled, forming fine equiaxed crystals. These crystals then develop into dendrites under the combined influence of the temperature gradient and the solute concentration at the solid-liquid interface. Simultaneously, the temperature difference at the mold wall triggers strong convection of the liquid metal, eroding the initial dendrites formed from the fine equiaxed crystals, causing them to fracture, segregate, and detach. The resulting strong convection inhibits the growth of these dendrites, thus forming a thick band of fine equiaxed crystals on the outer surface of the ingot, which seriously affects the quality of the ingot.

[0003] To improve the solidification structure of steel ingots, existing technologies have conducted research on dynamic solidification of steel ingots. Currently, the "one mold, one vibration" mode is mostly adopted, that is, a single steel ingot mold is equipped with an independent immersion vibration device, such as the vibration solidification of large slab steel ingots and the vibration forming of large water-cooled mold wall castings. By inserting an immersion vibration device into the steel ingot mold to vibrate and solidify the steel ingot, the solidification effect can be improved to a certain extent. However, this mode not only has limited production efficiency and is not suitable for large-scale production, but also the immersion vibration device is constantly subjected to the scouring of high-temperature molten steel, making it easy to be adhered to by the molten steel. In addition, the oxide scale and coating adhering to the surface of the immersion vibration device are easy to fall off and enter the molten steel, forming external inclusions and reducing the purity of the steel ingot. Summary of the Invention

[0004] The purpose of this invention is to provide a dynamic solidification system and solidification method for steel ingots, in order to solve the problems of low generation efficiency and the formation of external inclusions that reduce the purity of steel ingots in existing single-mold-one-vibration systems using immersion vibration devices.

[0005] The technical solution of this invention is: A dynamic solidification system for steel ingots includes a casting system, a vibration device, and a controller. The casting system includes a casting base, multiple sets of steel ingot molds, and a casting pipe. The multiple sets of steel ingot molds are fixed on the top of the casting base, and the casting pipe is connected to the multiple sets of steel ingot molds. The vibration device is a non-insertion type, and its vibration output end is connected to the casting base to apply a vibration force to the casting base. The controller is used to adjust the excitation frequency of the vibration device according to the overall mass of the vibrating body composed of the casting base, the casting pipe, and the multiple sets of steel ingot molds, so that the excitation frequency of the vibration device is equal to the natural frequency of the vibrating body to achieve resonance of the casting system.

[0006] Preferably, as a further improvement of the present invention, a positioning groove is provided at the top edge of the casting base, and the vibration output end of the excitation device extends into the positioning groove and contacts the casting base.

[0007] Preferably, as a further improvement of the present invention, the non-insertion excitation device is an inertial exciter or an electric exciter.

[0008] Preferably, as a further improvement of the present invention, the materials of the casting base, the ingot mold, and the casting pipe are the same.

[0009] Preferably, as a further improvement of the present invention, the materials of the casting base, the ingot mold, and the casting pipe are all made of any one of cast iron, cast steel, and heat-resistant cast steel.

[0010] Preferably, as a further improvement of the present invention, the casting pipe is disposed at the center of the casting base, and multiple sets of steel ingot molds are evenly distributed around the outside of the casting pipe with the center line of the casting pipe as the center. The bottom of each steel ingot mold is connected to the bottom of the casting pipe.

[0011] This invention also discloses a method for dynamic solidification of steel ingots, implemented using the aforementioned dynamic solidification system for steel ingots, comprising the following steps: Molten steel is poured simultaneously into each steel ingot mold through the pouring pipe; The excitation force is applied to the casting base by the excitation device, and the excitation frequency of the excitation device is adjusted according to the overall mass of the cast-in-place body composed of the casting base, the casting pipe and multiple sets of steel ingot molds, so that the excitation frequency is equal to the natural frequency of the cast-in-place body. The excitation wave and the reflected wave are superimposed by the vibration symmetry to form a symmetrically distributed standing wave that synchronously resonates with multiple steel ingot molds. Vibration stops after the preset vibration time is reached, and the ingot is demolded after solidification.

[0012] Preferably, as a further improvement of the present invention, when the excitation frequency is equal to the natural frequency of the casting system, the mass of the vibrating body in the casting system, the elastic coefficient of the vibrating body, and the angular frequency of the excitation device satisfy the following relationship: k 2= m 2 In the formula, k2 is the elastic modulus of the vibrating body, and m2 is the mass of the vibrating body. ω 1 represents the angular frequency of the excitation device.

[0013] Compared with the prior art, the beneficial effects of the present invention are: 1. Breaking away from the traditional "one mold, one vibration" model, molten steel is poured into multiple ingot molds simultaneously through the pouring pipe, and a vibration device is used to apply resonant excitation force on the pouring base, realizing synchronous resonant dynamic solidification of multiple ingot molds. During the dynamic solidification process, vibration enhances the convection at the solid-liquid interface, accelerates solute diffusion, inhibits dendritic crystals, reduces component segregation inside the ingot, refines the grains, and achieves a dispersed distribution of inclusions. The homogenization level and overall quality of the ingot are greatly improved, ensuring the integrity of the ingot and the continuity of production.

[0014] 2. A non-immersion vibration device that does not come into contact with molten steel is adopted. The vibration force is applied directly to the casting base through the vibration device without entering the molten steel, which fundamentally avoids the risk of burn-out of the vibrating rod and the peeling and residue of attached oxide scale and coating, thus ensuring the purity of the steel ingot. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of a dynamic solidification system for steel ingots according to an embodiment of the present invention.

[0016] Figure 2 This is a schematic diagram of the steps of a dynamic solidification method for steel ingots according to an embodiment of the present invention.

[0017] Figure 3 This is a graph showing the relationship between the mass of the vibrating body and the angular frequency of the excitation body in a dynamic solidification method for steel ingots according to an embodiment of the present invention. Detailed Implementation

[0018] The following is combined Figures 1-3 The specific embodiments of the present invention will be described in detail below. In the description of the invention, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0019] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature; in the description of the invention, unless otherwise stated, "a plurality of" means two or more.

[0020] Example 1 like Figure 1 As shown, this embodiment of the invention provides a dynamic solidification system for steel ingots, including a casting system, a vibration device 4, and a controller.

[0021] The casting system includes a casting base 1, multiple sets of steel ingot molds 2, and a casting pipe 3. The casting pipe 3 is located at the center of the casting base 1. The multiple sets of steel ingot molds 2 are fixed on the top of the casting base 1 and are evenly distributed around the outside of the casting pipe 3 with the center line of the casting pipe 3 as the center. The bottom of each steel ingot mold 2 is connected to the bottom of the casting pipe 3 to form a closed and independent casting system.

[0022] Among them, the excitation device 4 is a non-insertion type excitation device, which does not come into direct contact with molten steel, thus avoiding equipment damage and safety hazards caused by direct contact with high-temperature molten steel. The vibration output end of the excitation device 4 is connected to the casting base 1, and the excitation force is transmitted to the entire casting system through the casting base 1. It does not penetrate the molten steel, thus fundamentally avoiding the risk of burn-out of the vibrating rod and the peeling and residue of the attached oxide scale and coating, and ensuring the purity of the steel ingot.

[0023] The controller is used to adjust the vibration parameters of the excitation device 4 and control the excitation device 4 to apply a resonant excitation force to the casting base 1. The vibration parameters include vibration frequency, vibration time and amplitude. The excitation frequency of the excitation device 4 is adjusted according to the overall mass of the vibrating body composed of the casting base 1, the casting pipe 3 and multiple sets of steel ingot molds 2, so that the excitation frequency of the excitation device 4 is equal to the natural frequency of the vibrating body. In this way, the symmetry of vibration is used to make the excitation wave and the reflected wave superimpose to form a symmetrically distributed standing wave that synchronously resonates with the multiple steel ingot molds 2. The vibration strengthens the solid-liquid interface convection, accelerates solute diffusion, suppresses dendrites, reduces the segregation of components inside the steel ingot, refines the grains, and achieves a dispersed distribution of inclusions. The homogenization level and overall quality of the steel ingot are greatly improved, ensuring the integrity of the steel ingot and the continuity of production.

[0024] As a further optimization of the above solution, in this embodiment, a positioning slot is provided at the top edge of the casting base 1, and the vibration output end of the excitation device 4 extends into the positioning slot and contacts the casting base 1. Through the above arrangement, the excitation device 4 is positioned so that the vibration wave under the action of the excitation device 4 is symmetrically distributed in the casting system.

[0025] In practice, the excitation device 4 may be an inertial exciter or an electric exciter.

[0026] As a further optimization of the above scheme, the materials of the casting base 1, the steel ingot mold 2, and the casting pipe 3 are the same, thus achieving a homogeneous structure among the three and ensuring the uniformity of resonance of multiple steel ingot molds.

[0027] In practice, the materials of the casting base 1, the steel ingot mold 2, and the casting pipe 3 can all be any one of cast iron, cast steel, and heat-resistant cast steel.

[0028] Example 2 This embodiment is based on embodiment 1, such as... Figures 2-3 As shown, a dynamic solidification method for steel ingots is also disclosed, which is based on the above-mentioned dynamic solidification system for steel ingots and includes the following steps: S1. Determine the amount of molten steel to be poured, and pour the molten steel into each steel ingot mold 2 simultaneously through the pouring pipe 3.

[0029] Based on the weight of the forging and the inverse relationship between the elastic modulus of the vibrating body and the square of the angular frequency of the excitation body, the formula is used... m 2× = k 2. Determine the appropriate mass of the vibrating body, and dynamically configure the corresponding grade of steel ingots accordingly, and determine the casting volume. Where, k 2 is the elastic modulus of the vibrating body. m 2 represents the mass of the vibrating body. ω 1 represents the angular frequency of the excitation device; after the qualified molten steel is smelted, it is poured into each steel ingot mold 2 simultaneously through the pouring pipe 3 to complete the pouring process into multiple steel ingot molds.

[0030] Specifically, the formula used to determine the fit mass of the vibrating body is... m 2× ≈ k 2 is obtained through the following derivation process: Resonance refers to the phenomenon where a system resonates violently when the frequency of an external force equals the natural frequency of the object being forced, with the amplitude reaching its maximum value.

[0031] The vibration frequency of the exciter: f1= , In the formula: k 1 represents the elastic modulus of the exciter; m 1 represents the mass of the excitation body.

[0032] The natural frequency of the vibrating body: f2 = , In the formula: k 2 represents the elastic modulus of the vibrating body; m 2 represents the mass of the vibrating body.

[0033] To achieve the best vibration effect, the condition for resonance should be met, making the excitation frequency equal to the natural frequency of the vibrating body, that is: f1=f2, = , Among them, the frequency f1 of the exciter has been obtained or controlled; And: f1 = , because: ω =2 π f, In the formula, ω f1 is the angular frequency; so: ω 1=2 π f1, In the formula, ω 1 is the angular frequency of the exciter, and f1 is the frequency of the exciter. After algebraic transformation, we get: 2 π f1= ; ω 1= Squaring both sides of the equals sign and rearranging the terms: m 2= or k 2= m 2 This is used to determine the maximum mass that may cause the vibrating body to resonate in the vibrator. m 2.

[0034] in: ω 1 represents the rotational angular frequency of the exciter (rad / s, radians / second). k 2 represents the elastic modulus (GPa) of the vibrating body. The relationship between angular frequency (angular velocity) and rotational speed is as follows: ω = 2πN; in, ω Let ω be the angular frequency and N be the rotational speed.

[0035] Note: Angular frequency can be expressed in rad and rpm, where rpm = 60 rad; 1 Pa = 0.1 kgf / m 2 ; 1GPa = 1000MPa = 109Pa=108kgf / m 2 , According to the metal materials handbook, the elastic modulus of cast iron is 160 GPa to 180 GPa.

[0036] Therefore, this is used as the elastic coefficient of the entire gating system (casting base 1 + ingot mold 2 + gating pipe 3), and the mass of the entire gating system (casting base 1 + ingot mold 2 + gating pipe 3) is... m 2.

[0037] Because, once the material of the object subjected to vibration is determined, its material properties (such as the elastic modulus) are... k 2) It is definite, and it is a constant in the operation process.

[0038] S2. Apply excitation force to the casting base 1 through the excitation device 4, and adjust the excitation frequency of the excitation device 4 according to the overall mass of the vibrating body composed of the casting base 1, the casting pipe 3 and multiple sets of steel ingot molds 2, so that the excitation frequency is equal to the natural frequency of the vibrating body. Utilize the symmetry of vibration to make the excitation wave and the reflected wave superimpose to form a symmetrically distributed standing wave that synchronously resonates with the multiple steel ingot molds 2.

[0039] Since the multi-ingot mold 2, the casting base 1, and the casting pipe 3 constitute a closed, independent, and non-dissipative ingot casting system, the casting system is a typical Bohr resonance theory model. In the same plane, the standing wave formed by the superposition of the excitation wave generated by the excitation source and the reflected wave has a symmetrical distribution of nodal lines and nodal line shapes.

[0040] By making the excitation frequency f1 equal to the natural frequency f2 of the casting system as the vibrating body, the resonance condition f_excitation≈f_forced vibration is satisfied, thereby allowing the casting system to generate symmetrical vibration waves and resonate under external excitation, so that the amplitude reaches the maximum value.

[0041] S3. Demolding and hot forging: Determine the duration of continuous vibration based on the size of the steel ingot. Stop vibration after the preset vibration time is reached. After the steel ingot has solidified, demold and hot forge the steel ingot.

[0042] The rated speed of the excitation device 4 is adjustable. By adjusting the rated speed, the angular frequency ω1 of the exciter can be changed, thereby adapting to the vibrating body of different masses. According to calculations, the excitation device 4 can make the maximum resonant mass range of the vibrating body 15.5 tons to 43 tons, and the range of vibrating body mass adaptability can be further expanded by adjusting the speed to meet the production needs of steel ingots of different grades.

[0043] Furthermore, the excitation device 4 uses exciters of models such as VA0808, VA2010, VA2508, and VA3506. The exciter model is matched according to the maximum processing weight of the steel ingot. The speed stability of the exciter is ±1 rpm, the rated voltage is 180V, and it is compatible with a power frequency of 50Hz to ensure the stability of the excitation device and the accuracy of the vibration parameters.

[0044] Furthermore, the number of multi-ingot molds and the size of the ingots can be flexibly adjusted according to production needs. The vibration frequency of the excitation device is adjusted synchronously with the size of the ingots and the number of multi-ingot molds to ensure the dynamic solidification effect of multi-mold resonance and adapt to different production conditions.

[0045] To verify the effect of vibration on the cooling and crystallization process of steel ingots, this invention conducted three low-temperature physical simulation experiments. The experimental setup consisted of a cooling tank, a solidification mold, a vibrator, and a support platform. By comparing the solution crystallization time and solidified morphology under conditions with and without vibration, the following experimental results were obtained: When ice is added to the coolant and the temperature is kept constant, and the temperature difference between the solution and the coolant is 106℃, the sample with vibration crystallizes in a relatively short time and does not show dendritic needles (the dendrites are destroyed by vibration). The crystal rain is fine, the solidification is uniform, and the upper end of the solidified solid is regular and smooth, resembling the bottom of a pot. The sample without vibration crystallizes in a longer time, and the upper end of the solidified solid has an irregular depression in the middle. When no ice is added to the coolant and the temperature difference between the solution and the coolant is 81℃, the sample with vibration has a relatively shorter crystallization time, a later appearance of dendritic needles, fine crystal rain, and a smooth and uniform end face; the sample without vibration has coarse crystal rain and honeycomb-like holes on the end face. When the coolant temperature is 21℃ and the temperature difference between the solution and the coolant is 79℃, the crystal points of the vibrating sample are dispersed, the crystal rain is fine, and only slight shrinkage cavities appear; the crystal rain of the non-vibrating sample is coarse, with mountain-shaped pits, and severe shrinkage cavities exist.

[0046] The above experimental results show that vibration has a significant effect on inhibiting dendrite growth. The vibrated samples have finer and more diffusely distributed crystal rain, smoother crystal end faces, significantly improved solidification uniformity, and significantly reduced defects such as shrinkage cavities.

[0047] The present invention calculates and determines the maximum resonant mass of the vibrating body using the following parameters, the specific calculation parameters and results of which are shown in Table 1: Table 1 Calculation of the maximum mass of the vibrating body .

[0048] The above calculation results show that the rated speed of the selected excitation device 4 has a maximum mass of approximately 15.5 tons to 43 tons that can cause the vibrating body to resonate. The angular frequency of the excitation body can be changed by adjusting the rated speed of the excitation device 4, thereby increasing the mass of the vibrating body and adapting to the casting requirements of steel ingots of different sizes.

[0049] The above-disclosed embodiments are merely preferred embodiments of the present invention. However, the embodiments of the present invention are not limited thereto, and any variations that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. A dynamic solidification system for steel ingots, characterized in that, Includes the gating system, vibration device, and controller; The casting system includes a casting base, multiple sets of steel ingot molds, and a casting pipe. The multiple sets of steel ingot molds are fixed on the top of the casting base, and the casting pipe is connected to the multiple sets of steel ingot molds. The excitation device is a non-insertion type excitation device, and its vibration output end is connected to the casting base to apply excitation force to the casting base. The controller is used to adjust the excitation frequency of the excitation device according to the overall mass of the vibrating body composed of the casting chassis, casting pipe and multiple sets of steel ingot molds, so that the excitation frequency of the excitation device is equal to the natural frequency of the vibrating body to achieve resonance of the casting system.

2. The dynamic solidification system for steel ingots according to claim 1, characterized in that, A positioning slot is provided at the top edge of the casting base, and the vibration output end of the excitation device extends into the positioning slot and contacts the casting base.

3. The dynamic solidification system for steel ingots according to claim 2, characterized in that, The non-insertion excitation device is an inertial exciter or an electric exciter.

4. The dynamic solidification system for steel ingots according to claim 1, characterized in that, The casting base, the steel ingot mold, and the casting pipe are all made of the same material.

5. The dynamic solidification system for steel ingots according to claim 4, characterized in that, The casting base, the ingot mold, and the casting pipe are all made of any one of cast iron, cast steel, or heat-resistant cast steel.

6. The dynamic solidification system for steel ingots according to claim 1, characterized in that, The casting pipe is located at the center of the casting base, and multiple sets of steel ingot molds are evenly distributed around the outside of the casting pipe with the center line of the casting pipe as the center. The bottom of each steel ingot mold is connected to the bottom of the casting pipe.

7. A method for dynamic solidification of steel ingots, implemented using the dynamic solidification system for steel ingots as described in any one of claims 1 to 6, characterized in that, Includes the following steps: Molten steel is poured simultaneously into each steel ingot mold through the pouring pipe; The excitation force is applied to the casting base by the excitation device, and the excitation frequency of the excitation device is adjusted according to the overall mass of the cast-in-place body composed of the casting base, the casting pipe and multiple sets of steel ingot molds, so that the excitation frequency is equal to the natural frequency of the cast-in-place body. The excitation wave and the reflected wave are superimposed by the vibration symmetry to form a symmetrically distributed standing wave that synchronously resonates with multiple steel ingot molds. Vibration stops after the preset vibration time is reached, and the ingot is demolded after solidification.

8. The method for dynamic solidification of steel ingots according to claim 7, characterized in that, When the excitation frequency is equal to the natural frequency of the casting system, the mass of the vibrating body in the casting system, the elastic coefficient of the vibrating body, and the angular frequency of the excitation device satisfy the following relationship: k 2= m 2 In the formula, k 2 is the elastic modulus of the vibrating body. m 2 represents the mass of the vibrating body. ω 1 represents the angular frequency of the excitation device.

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