Vacuum rapid smelting device for controlling temperature of molten steel and control method of vacuum rapid smelting device

Abstract

The invention relates to a vacuum rapid smelting device for controlling the temperature of molten steel and a control method thereof.The vacuum rapid smelting device comprises a crucible, an induction coil, a shell and a base, and the crucible is of a columnar structure, is hollow and is used for loading and melting charge bars; the induction coil is arranged on the outer wall of the crucible in a sleeving manner and is used for heating a charge bar in the crucible through electromagnetic induction; the shell is connected to the lower end of the crucible in a penetrating mode and used for receiving molten steel and cooling the molten steel to form a casting. An adjustable gap height H1 is arranged between the induction coil and the shell, the charge bar extends out of the induction coil, and the extension distance H2 from the peak of the charge bar to the peak of the induction coil is adjustable. The device is compact and reasonable in structure and convenient to operate, by adjusting the relative position relation of the charge bar and the induction coil, the temperature of molten steel is accurately controlled, the production efficiency is improved, the energy consumption cost is reduced, the process adaptability and flexibility are enhanced, the temperature control problem in a traditional smelting process is solved, casting defects are effectively prevented, and the casting quality is improved.

Description

Technical Field

[0001] The invention relates to the technical field of precision casting, in particular to a vacuum rapid melting device for controlling the temperature of molten steel and a control method thereof. Background Art

[0002] The current precision casting fast melting process uses a mold shell crucible to load the material rod, enter the vacuum chamber for melting, and at the same time, the material rod is extended into the inductor for melting. The mainstream process setting is that during melting, the upper part of the material rod is induction heated by the induction magnetic field of the inductor, and a small part of the material rod at the lower end is exposed to the bottom of the inductor. After the molten steel at the upper end melts the material rod at the lower end that is not induction heated by induction through heat conduction, all the molten steel can enter the mold shell cavity at one time to complete the casting.

[0003] With the implementation of the National VI emission requirements, more and more engine supercharger manufacturers tend to design the turbine into a full back plate shape ( Figure 1 For conventional turbines, Figure 2 It is a full back plate turbine) with the aim of improving the response speed and performance of the turbine and achieving more complete combustion.

[0004] The new design of the National VI turbine has put forward higher requirements on the fast melting process. The full-back plate turbine has an adverse effect on the cooling stress of the casting turbine, and the probability of blade cracking has increased significantly. However, at the same time, the traditional vacuum rapid melting process is not conducive to the processing of the full-back plate turbine. The resulting contradiction is that the temperature of the molten steel in the fast melting process is relatively high, resulting in many scrap defects such as fluorescent porosity, fluorescent cracking, fluorescent shrinkage, etc. in the casting, which brings many unstable factors to the product quality.

[0005] The main reasons are as follows: the traditional vacuum rapid melting process is as follows: after the material rod is loaded into the roasted shell crucible, the upper part of the material rod enters the induction coil, and the lower part of the material rod ( Figure 3 The gap height H1) will expose the lower end of the inductor by 20-40mm. When the vacuum degree in the melting chamber reaches ≤10Pa, the induction coil starts to be energized to transmit power, so that the material rod in the induction coil is inductively heated and begins to melt into molten steel. After the upper part of the material rod is completely melted into molten steel, the material rod exposed to the lower end of the inductor (no induction heating area) will be melted by the heat conduction of the molten steel until the material rod exposed to the lower end of the inductor is melted. At this time, the molten steel in the crucible will enter the mold cavity to complete the casting and filling, and form a metal casting after cooling.

[0006] Traditional vacuum rapid melting has a typical disadvantage, which is that when the upper part of the material bar is melted into molten steel, the induction coil is still energized to deliver power, and the molten steel will continue to heat up, usually reaching above 1600°C. The overheated molten steel will melt the material bar that is not in the induction heating area through heat conduction, and finally complete the filling. In this process, the temperature of the molten steel will be heated to 1750°C, which is higher than the decomposition temperature of the mold shell material; and the heavier the material bar, the more serious this overheating phenomenon will be, mainly because the longer the material bar, the longer the length of induction heating in the inductor will be, and more molten steel will be produced. Therefore, in order to prevent the molten steel from entering the mold shell cavity in advance, usually the lower end of the material bar is exposed to the inductor part ( Figure 1 The gap height H1) in the casting will be larger, which means that the molten steel needs longer time to melt the exposed part of the lower end of the material rod. At this time, the molten steel will be continuously heated until the molten steel is fully filled. Too long heating time will lead to high molten steel temperature, which will lead to many scrap defects such as fluorescent looseness, fluorescent cracking, fluorescent shrinkage, etc. of the casting, bringing many unstable factors to product quality.

[0007] At the same time, for the processing of full backplane turbines, it is also necessary to improve the melting efficiency. Through fast melting, the material can be quickly heated to a molten state, and the cooling process can be precisely controlled to achieve rapid prototyping of turbine components. This greatly shortens the processing cycle, improves production efficiency, and reduces the heat-affected zone: due to the fast melting speed and rapid cooling of fast melting technology, the scope of the heat-affected zone can be reduced, thereby reducing the adverse effects on the performance of the substrate. Therefore, if fast melting is achieved, increasing the temperature is the best way, but increasing the temperature will affect product performance.

[0008] Therefore, we need to find a better way to achieve fast melting within a reasonable temperature range while improving product quality.

[0009] For this reason, we propose a vacuum rapid melting device for controlling the temperature of molten steel and a control method thereof. Summary of the invention

[0010] In view of the shortcomings of the above-mentioned existing production technology, the applicant provides a vacuum rapid melting device for controlling the temperature of molten steel and a control method thereof. By adjusting the relative position relationship between the material rod and the induction coil, the temperature of the molten steel can be accurately controlled, the production efficiency can be improved, the energy consumption cost can be reduced, and the process adaptability and flexibility can be enhanced.

[0011] The technical solution adopted by the present invention is as follows:

[0012] A vacuum rapid melting device for controlling the temperature of molten steel comprises a crucible, an induction coil, a mold shell and a base.

[0013] The crucible is a columnar structure with a hollow interior, and is used to load and melt the material rods;

[0014] The induction coil is sleeved on the outer wall of the crucible and is used to heat the material rod in the crucible by electromagnetic induction;

[0015] The mold shell is connected to the lower end of the crucible and is used to receive molten steel and cool it to form a casting;

[0016] An adjustable gap height H1 is provided between the induction coil and the mold shell, the material rod extends out of the induction coil, and the extension distance H2 from the top of the material rod to the highest point of the induction coil is adjustable in length.

[0017] Furthermore, the crucible is made of aluminum silicate fiber.

[0018] Furthermore, it also includes a base, which is used to support the entire smelting device.

[0019] Furthermore, it also includes an adjusting mechanism for adjusting the height of the induction coil, and the adjusting mechanism can manually or automatically adjust the position of the induction coil on the crucible.

[0020] Furthermore, the height adjustment methods of the induction coil include increasing or decreasing the number of coil turns, the cross-sectional size of each coil turn, changing the coil spacing, etc.

[0021] Furthermore, it also includes a temperature sensor for real-time monitoring of the temperature of the molten steel and feeding back the temperature information to the regulating mechanism to achieve precise control of the temperature of the molten steel.

[0022] A method for effectively controlling the temperature of molten steel in a fast melting process, which uses a vacuum fast melting device for controlling the temperature of molten steel as claimed in claim 6, comprising the following steps:

[0023] While ensuring that the length of the material rod remains unchanged, the material rod is loaded into the crucible, and the height of the induction coil is adjusted by adjusting the structure so that the gap height H1 is about 15% of the material rod height, the extension distance H2 is 8%-15% of the material rod height, and the extension distance H2 ≤ gap height H1, so as to achieve precise control of the molten steel temperature and improve the casting quality and production efficiency.

[0024] A method for effectively controlling the temperature of molten steel in a fast melting process, which uses a vacuum fast melting device for controlling the temperature of molten steel as described in claim 6, by extending the length of the material rod and making the extension distance H2 greater than 0, and at the same time making the extension distance H2 ≤ gap height H1.

[0025] Furthermore, the extension distance H2 / gap height H1 is close to 0.6-1.0.

[0026] Further, the molten steel temperature: Q molten steel = UIt-IR2t-Q gap height H1-Q extension distance H2; wherein:

[0027] Q molten steel is the heat content of molten steel before filling;

[0028] UIt is the current work done from the start of the inductor power supply to the time before the molten steel is filled into the mold;

[0029] IR2t is the heat loss caused by sensor heating;

[0030] Q The gap height H1 is the heat loss caused by the melting of the molten steel and the bar exposed at the lower end of the inductor;

[0031] Q extension distance H2 is the heat loss caused by the melting of molten steel and the material rod exposed at the upper end of the inductor.

[0032] The beneficial effects of the present invention are as follows:

[0033] The present invention has a compact and reasonable structure and is easy to operate. By adjusting the relative position relationship between the material rod and the induction coil, the temperature of the molten steel can be accurately controlled, production efficiency can be improved, energy consumption costs can be reduced, and process adaptability and flexibility can be enhanced. At the same time, the temperature control problem in the traditional smelting process is solved, casting defects are effectively prevented, and the quality of castings is improved.

[0034] At the same time, the present invention also has the following advantages:

[0035] 1. Significantly improve the quality of castings: The vacuum rapid smelting device and its control method of the present invention can achieve precise control of the temperature of molten steel. This breakthrough in key technology effectively solves the problem of casting defects caused by excessive molten steel temperature in the traditional smelting process, such as fluorescent porosity, fluorescent cracking, fluorescent shrinkage, etc. Accurate temperature control enables the molten steel to form a more uniform and dense microstructure during the solidification process, thereby significantly improving the mechanical properties, fatigue resistance and corrosion resistance of the casting. This is of great significance for improving the overall quality of key components such as engine superchargers and extending their service life.

[0036] 2. Significantly improve production efficiency: The fast melting process of the present invention is combined with an automated control system to achieve rapid startup, stable operation and efficient completion of the smelting process. Compared with traditional processes, this method significantly shortens the smelting cycle and processing time, and reduces waiting and idle time in the production process. At the same time, the application of automated control systems reduces dependence on manual operation, reduces the occurrence of human errors, and further improves production efficiency and stability. This is of great significance for meeting the needs of modern manufacturing for high-efficiency, high-quality products.

[0037] 3. Effectively reduce energy consumption costs: By accurately controlling the power and heating time of the induction coil, the present invention effectively avoids energy waste caused by excessive molten steel temperature. During the smelting process, the system can monitor the molten steel temperature in real time and adjust it as needed to ensure that the molten steel melts within the appropriate temperature range. This precise energy input method not only improves energy utilization efficiency, but also reduces production costs. In addition, due to the shortened smelting cycle and reduced processing time, the equipment operation cost and maintenance cost are further reduced.

[0038] 4. Enhanced process adaptability and flexibility: The vacuum rapid melting device and control method of the present invention have wide applicability and flexibility. By adjusting parameters such as the height of the induction coil, the gap height, and the extension distance, it can adapt to the melting requirements of metal rods of different materials, sizes, and shapes. This feature gives the device a significant advantage in the manufacture of high-precision, complex-shaped castings. In particular, for the manufacture of high-precision castings such as full-backplate turbines, the present invention can provide a more stable and reliable melting process solution to meet the needs of modern manufacturing for product diversification and personalization. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a schematic diagram of the structure of a traditional turbine in the background technology of the present invention.

[0040] Figure 2 It is a structural schematic diagram of a full backplate turbine in the background technology of the present invention.

[0041] Figure 3 It is a schematic structural diagram of a conventional vacuum rapid melting device in the background technology of the present invention.

[0042] Figure 4 It is a schematic diagram of the structure of the vacuum rapid smelting device in the present invention.

[0043] Among them: 100, crucible; 200, material rod; 300, induction coil; 400, mold shell; 500, base. DETAILED DESCRIPTION

[0044] The specific implementation of the present invention will be described below in conjunction with the accompanying drawings.

[0045] Embodiment 1

[0046] like Figure 4 As shown, this embodiment discloses a vacuum rapid melting device for controlling the temperature of molten steel, and its structure includes a crucible 100, an induction coil 300, a mold shell 400 and a base 500, which are used to melt the material rod 200 and cool the molten steel to form a casting;

[0047] The most significant feature is that the vacuum rapid melting device in this embodiment can control and adjust the extension distance H2 of the highest point of the material rod 200 extending out of the induction coil 300 .

[0048] Specifically, the crucible 100 is a columnar structure with a hollow interior, providing space for the melting of the material rod 200; the material rod 200 is prevented from being distributed along the axial direction of the crucible 100; the material of the crucible 100 is aluminum silicate fiber, which is also called ceramic fiber. It is a new, lightweight, energy-saving refractory material with the advantages of light bulk density, high temperature resistance, good thermal stability, low thermal conductivity, good resistance to mechanical vibration, small thermal expansion, and good thermal insulation performance. The aluminum silicate fiber crucible has strong stability within a certain range, but its performance decreases when the temperature is too high. Therefore, the use of aluminum silicate fiber crucible can improve product quality under certain temperature conditions. In addition, due to the low thermal conductivity of the aluminum silicate fiber crucible, the heat is more concentrated in the position of the induction coil 300, so the temperature of other positions of the crucible is relatively low.

[0049] The induction coil 300 is sleeved on a section of the outer wall of the crucible 100 and heats the corresponding position on the crucible 100 by electromagnetic induction;

[0050] The shell mold 400 is connected to the lower end of the crucible 100 and is used to receive the molten material rod 200 and form a turbine casting with a full back plate after being cooled in the shell mold 400;

[0051] The base 500 is used to support the entire smelting device to ensure its stability.

[0052] At the same time, in order to increase or decrease the temperature of the molten steel and save energy at the same time, there is a gap height H1 between the bottom of the induction coil 300 and the mold shell 400, that is, the side wall of the crucible 100 within the range of the gap height H1 is not provided with the induction coil 300. In actual use, the induction coil 300 drives the corresponding side wall of the material rod 200 to be heated, and the high-temperature molten steel after heating and melting flows downward, which can heat-conduct and melt the material rod 200 within the gap height H1, and the molten steel can fully contact the material rod 200 to improve the melting efficiency. In addition, since the molten steel here is not directly heated, the temperature of the molten steel is close to the melting point temperature of the material rod here, and the material rod continues to be melted by natural convection and conduction, while avoiding excessive temperature caused by direct heating, thereby achieving the melting of the entire material rod 200 without the need to provide the induction coil 300 on the outer wall of the entire crucible 100, and also avoiding the problem of poor temperature control and easy energy waste caused by providing the induction coil 300 on the outer wall of the entire crucible 100.

[0053] In this embodiment, there are two methods for adjusting the relative position of the material rod 200 and the induction coil 300 so that the top of the material rod 200 extends out of the induction coil 300:

[0054] First, in the conventional vacuum rapid melting device, a heavy material bar 200 is used. Since the diameter of the material bar 200 is determined, the weight increases, that is, the height of the material bar 200 increases, so that the top of the material bar 200 extends out of the induction coil 300. However, since the size of the material bar 200 is generally fixed during production and processing, the length of the material bar 200 will not be easily adjusted in the entire melting industry in a short period of time. If the size limitation is exceeded in the later stage, the conventional vacuum rapid melting device can be used by adjusting the size, thereby improving the melting effect and quality;

[0055] This solution will lead to a decrease in process yield (process yield = part weight / bar weight), a sharp increase in production costs, and an adverse impact on the company's production operations;

[0056] Second, if Figure 4 As shown, the induction coil 300 in this embodiment is sleeved on the outer wall of the crucible 100. The height of the induction coil 300 is adjusted by changing the gap between the induction coils 300. That is, when the height of the induction coil 300 is reduced, the material rod 200 can be extended out of the induction coil 300. This method is more suitable for actual production operations because the manufacturing cost of the inductor is relatively low.

[0057] In this embodiment, the method of changing the gap of the induction coil 300 includes:

[0058] Manual adjustment: The operator manually adjusts the position of the induction coil 300 on the crucible 100 according to actual needs, and reduces the overall height of the coil by increasing or decreasing the number of coil turns, the cross-sectional size of each coil turn, changing the coil spacing, etc., so as to expose the top of the material rod. This method is simple to operate, but depends on the experience and skill level of the operator.

[0059] Automatic adjustment: In order to achieve more precise control, an automatic adjustment system can be used. The system monitors the relative position of the material rod 200 and the induction coil 300 in real time through sensors, and automatically adjusts the coil height according to preset parameters. The automatic adjustment system usually includes a telescopic mechanism, a controller, and a feedback device, which can ensure that the optimal extension distance H2 is always maintained during the smelting process.

[0060] The vacuum rapid melting device and control method of the present invention can adjust the relative position relationship between the material rod and the induction coil to accurately control the temperature of the molten steel, improve production efficiency, reduce energy consumption costs, enhance process adaptability and flexibility, improve the working environment and protect the health of workers, and significantly improve the overall level of the precision casting industry. This technological breakthrough solves the temperature control problem in the traditional melting process, effectively prevents casting defects, and improves the quality of castings.

[0061] Embodiment 2

[0062] On the basis of the first embodiment, the embodiment discloses a method for effectively controlling the temperature of molten steel in a fast melting process. When using a vacuum fast melting device for processing, by adjusting the relative position of the induction coil 300 and the length of the material rod 2, a method for effectively controlling the temperature of molten steel is successfully developed, so that the melting position of the material rod 2 in the induction coil 300 is transferred from the upper half to the middle part, thereby effectively reducing the temperature of the molten steel after melting;

[0063] In this embodiment, the control principle of molten steel temperature is first analyzed, which includes:

[0064] During the vacuum rapid melting process, the temperature of the molten steel is mainly determined by the heating power of the induction coil, the thermal conductivity of the crucible and the material rod, the convection and radiation heat dissipation of the molten steel, etc. This embodiment effectively reduces the instantaneous temperature of the molten steel by adjusting the relative position of the induction coil and the material rod, especially by introducing the gap height H1 and the distance H2 extending out of the inductor. The principle is:

[0065] The role of the gap height H1: When the molten steel flows through the H1 area, it continues to melt the incompletely melted part of the material rod through natural convection and conduction, while avoiding excessive temperature caused by direct heating. In addition, the existence of the H1 area also promotes the uniformity of heat distribution inside the molten steel.

[0066] Function of extension distance H2: The portion of the material rod 200 located at extension distance H2 is directly exposed to an environment with relatively low temperature. After the portion of the material rod 200 located at the heating portion of the induction coil 300 is heated and melted, the portion of the material rod 2 located at extension distance H2 will gradually fall into the molten steel and absorb heat through heat conduction and melt into molten steel. In this process, the molten steel will still be heated, but since part of the solid material rod 2 directly enters the molten steel to absorb heat, the overall molten steel temperature will drop.

[0067] The top of the material rod 200 is extended out of the highest point of the induction coil 300, the extension distance is H2, the gap height H1 is about 15% of the height of the material rod 200, and the height of the extension distance H2 is 8%-15% of the height of the material rod 200; and the extension distance H2 ≤ the gap height H1, when the extension distance H2 / gap height H1 is close to 0.6-1.0, it meets the processing effect; thereby achieving rapid melting of the material rod at a lower temperature, improving the quality of the casting, and improving efficiency and reducing energy consumption.

[0068] After comparing the two solutions, it can be found that after the middle section of the material rod is melted into molten steel, the theoretical calculation formula of the molten steel heat is compared as follows:

[0069] like Figure 3As shown, the traditional vacuum rapid melting device: Q molten steel = UIt-IR2t-Q gap height H1

[0070] like Figure 4 As shown, in the vacuum rapid melting device of this embodiment: Q molten steel = UIt-IR2t-Q gap height H1-Q extension distance H2

[0071] Q molten steel is the heat content of molten steel before filling;

[0072] UIt is the current work done from the start of the inductor power supply to the time before the molten steel is filled into the mold;

[0073] IR2t is the heat loss caused by sensor heating;

[0074] Q The gap height H1 is the heat loss caused by the melting of the molten steel and the bar exposed at the lower end of the inductor;

[0075] Q extension distance H2 is the heat loss caused by the melting of molten steel and the material rod exposed at the upper end of the inductor.

[0076] It can be seen from this that the vacuum rapid smelting device in this embodiment can reduce the temperature of molten steel.

[0077] 1. Significantly improve the quality of castings: The vacuum rapid smelting device and its control method of the present invention can achieve precise control of the temperature of molten steel. This breakthrough in key technology effectively solves the problem of casting defects caused by excessive molten steel temperature in the traditional smelting process, such as fluorescent porosity, fluorescent cracking, fluorescent shrinkage, etc. Accurate temperature control enables the molten steel to form a more uniform and dense microstructure during the solidification process, thereby significantly improving the mechanical properties, fatigue resistance and corrosion resistance of the casting. This is of great significance for improving the overall quality of key components such as engine superchargers and extending their service life.

[0078] 2. Significantly improve production efficiency: The fast melting process of the present invention is combined with an automated control system to achieve rapid startup, stable operation and efficient completion of the smelting process. Compared with traditional processes, this method significantly shortens the smelting cycle and processing time, and reduces waiting and idle time in the production process. At the same time, the application of automated control systems reduces dependence on manual operation, reduces the occurrence of human errors, and further improves production efficiency and stability. This is of great significance for meeting the needs of modern manufacturing for high-efficiency, high-quality products.

[0079] 3. Effectively reduce energy consumption costs: By accurately controlling the power and heating time of the induction coil, the present invention effectively avoids energy waste caused by excessive molten steel temperature. During the smelting process, the system can monitor the molten steel temperature in real time and adjust it as needed to ensure that the molten steel melts within the appropriate temperature range. This precise energy input method not only improves energy utilization efficiency, but also reduces production costs. In addition, due to the shortened smelting cycle and reduced processing time, the equipment operation cost and maintenance cost are further reduced.

[0080] 4. Enhanced process adaptability and flexibility: The vacuum rapid melting device and control method of the present invention have wide applicability and flexibility. By adjusting parameters such as the height of the induction coil, the gap height, and the extension distance, it can adapt to the melting requirements of metal rods of different materials, sizes, and shapes. This feature gives the device a significant advantage in the manufacture of high-precision, complex-shaped castings. In particular, for the manufacture of high-precision castings such as full-backplate turbines, the present invention can provide a more stable and reliable melting process solution to meet the needs of modern manufacturing for product diversification and personalization.

[0081] Experimental example

[0082] In order to verify the effectiveness of the above design, we conducted a series of comparative experiments, specifically recording the effects of different gap heights H1 and H2 distances extending out of the sensor on molten steel temperature and casting quality. The experimental results show that with the increase of H2, the instantaneous temperature of the molten steel shows a significant downward trend, while the traces of chemical reactions on the casting surface are significantly reduced, and the scrap rate is greatly reduced.

[0083] Through multiple level tests on the length of the material rod extending out of the sensor, when the length of the material rod 200 remains unchanged, in this embodiment, the length of the material rod 200 is 200 mm, as shown in the following table:

[0084]

[0085]

[0086] From this we can conclude that:

[0087] The advantage of such a design is that under the condition of the same gap height H1, the same melting power is set, and it is measured that the instant molten steel temperature obtained by the vacuum rapid smelting device in this embodiment is more than 50°C lower than the instant molten steel temperature obtained by the traditional vacuum rapid smelting device, and the maximum temperature does not exceed 1550°C. At the same time, when the extension distance is H2 / gap height H1=25 / 30=0.83, the scrap rate is the lowest, and the value of the gap height H1 is within a reasonable range. The larger the value, the higher the stability of the scrap rate as the extension distance H2 changes.

[0088] The scrap rate increases sharply when the extension distance H2 reaches 35 mm, and the scrap rate is relatively high when the extension distance is 10 mm and 15 mm.

[0089] Therefore, the optimal ratio of the extension distance H2 to the material rod 200 is between 0.6 and 1.0.

[0090] Temperature reduction effect: When the gap height H1 is kept constant, the distance H2 is gradually increased, and it is found that the temperature of the molten steel gradually decreases. When H2 reaches a certain value, the temperature of the molten steel stabilizes in a lower range, meeting the temperature control requirements of casting forming. This proves that by adjusting the distance H2, the temperature of the molten steel can be effectively controlled to avoid casting quality problems caused by excessive temperature.

[0091] Improved casting quality: Due to the lower temperature of molten steel, the thermal stress on the casting during solidification is reduced, reducing the occurrence of defects such as cracks and deformation. At the same time, the lower molten steel temperature also inhibits the chemical reaction with the mold shell material, significantly reducing the traces of chemical reaction on the surface of the casting and improving the surface quality of the casting. Experimental data show that after adopting the new method, the scrap rate of castings has been reduced from about 50% to about 10%, with significant results.

[0092] Energy consumption and cost analysis: Although increasing the H2 distance may cause a slight decrease in the heating efficiency of the induction coil, the effective control of the molten steel temperature reduces the energy consumption required for additional cooling due to excessive temperature. At the same time, the reduction in the scrap rate of castings also indirectly reduces the production cost. Taking all factors into consideration, this embodiment not only improves the quality of castings, but also achieves dual optimization of energy consumption and cost.

[0093] In summary, it is found that the larger the extension distance H2, the lower the molten steel temperature, but it will also bring side effects. When the extension distance H2> the gap height H1, the material rod will not be completely melted.

[0094] 1. Before improvement: Due to the high temperature of molten steel, there are many traces of chemical reaction between the casting surface and the mold shell material, resulting in a large number of castings being scrapped, with a scrap rate of about 50%.

[0095] 2. After improvement: After using the new method, the chemical reaction traces on the casting surface are basically eliminated, and the scrap rate is about 10%, which is about 40 percentage points lower than before.

[0096] The vacuum rapid melting device and its operation method of this embodiment have been successfully applied in actual production. By accurately controlling the relative position of the material rod and the induction coil, the temperature of the molten steel is effectively controlled, which significantly improves the quality of the castings and the production efficiency.

[0097] The above description is an explanation of the present invention, not a limitation of the present invention. The scope of the present invention is defined in the claims. Any form of modification may be made within the scope of protection of the present invention.

Claims

1. A vacuum rapid melting device for controlling the temperature of molten steel, comprising a crucible, an induction coil, a shell and a base, characterized in that: The crucible is a columnar structure with a hollow interior, and is used to load and melt the material rods; The induction coil is sleeved on the outer wall of the crucible and is used to heat the material rod in the crucible by electromagnetic induction; the mold shell is connected to the lower end of the crucible and is used to receive molten steel and cool it to form a casting; an adjustable gap height H1 is provided between the induction coil and the mold shell, the material rod extends out of the induction coil, and the extension distance H2 from the top of the material rod to the highest point of the induction coil is adjustable.

2. A vacuum rapid melting device for controlling the temperature of molten steel as claimed in claim 1, characterized in that: The material of the crucible is aluminum silicate fiber.

3. A vacuum rapid melting device for controlling the temperature of molten steel as claimed in claim 1, characterized in that: The device also comprises a base, which is used to support the entire smelting device.

4. A vacuum rapid melting device for controlling the temperature of molten steel as claimed in any one of claims 1 to 3, characterized in that: The invention also comprises an adjusting mechanism for adjusting the height of the induction coil, wherein the adjusting mechanism can manually or automatically adjust the position of the induction coil on the crucible.

5. A vacuum rapid melting device for controlling the temperature of molten steel as claimed in claim 4, characterized in that: Ways to adjust the height of the induction coil include increasing or decreasing the number of coil turns, the cross-sectional size of each coil turn, changing the coil spacing, etc.

6. A vacuum rapid melting device for controlling the temperature of molten steel as claimed in claim 5, characterized in that: It also includes a temperature sensor for monitoring the temperature of the molten steel in real time and feeding back the temperature information to the regulating mechanism to achieve precise control of the temperature of the molten steel.

7. A method for effectively controlling the temperature of molten steel in a fast melting process, characterized in that: It uses a vacuum rapid melting device for controlling the temperature of molten steel as claimed in claim 6, comprising the following steps: While ensuring that the length of the material rod remains unchanged, the material rod is loaded into the crucible, and the height of the induction coil is adjusted by adjusting the structure so that the gap height H1 is about 15% of the material rod height, the extension distance H2 is 8%-15% of the material rod height, and the extension distance H2 ≤ gap height H1, so as to achieve precise control of the molten steel temperature and improve the casting quality and production efficiency.

8. A method for effectively controlling the temperature of molten steel in a fast melting process, characterized in that: It uses a vacuum rapid melting device for controlling the temperature of molten steel as claimed in claim 6, by extending the material The length of the rod is adjusted so that the extension distance H2 is greater than 0 and the extension distance H2 ≤ the gap height H1.

9. A method for effectively controlling the temperature of molten steel in a fast melting process as claimed in any one of claims 7 or 8, characterized in that: The extension distance is H2 / gap height H1, which is approximately 0.6-1.

0.

10. A method for effectively controlling the temperature of molten steel in a fast melting process as claimed in claim 9, characterized in that: The molten steel temperature: Q molten steel = UIt-IR2t-Q gap height H1-Q extension distance H2; wherein: Q molten steel is the heat content of molten steel before filling; UIt is the current work done from the start of the inductor power supply to the time before the molten steel is filled into the mold; IR2t is the heat loss caused by sensor heating; Q The gap height H1 is the heat loss caused by the melting of the molten steel and the bar exposed at the lower end of the inductor; Q extension distance H2 is the heat loss caused by the melting of molten steel and the material rod exposed at the upper end of the inductor.

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