Heating and heat preservation lead pan and using method thereof

Abstract

The invention relates to the technical field of lead-acid battery processing and production, in particular to a heating and heat preservation lead pan and a using method thereof.The heating and heat preservation lead pan comprises a support, a lead pan body and a heat preservation heating assembly, the support is arranged in a frame shape, the support bears and installs the lead pan body, and the lead pan body is arranged in an up-down layered mode and comprises a heat preservation area located on the upper layer and a heating area located on the lower layer; the heat preservation area conducts heat preservation on lead liquid, the heating area is arranged in an inverted circular truncated cone shape and conducts hot melting on lead blocks, the heat preservation heating assembly conducts heat preservation heating treatment on the heat preservation area and the heating area, the heat preservation heating assembly comprises a heating element, and the heating element is arranged on the outer side of the heating area in a surrounding mode. By the adoption of the electromagnetic induction heating technology, the heating and heat preservation lead pan can achieve rapid temperature rising, the heating efficiency is greatly improved, the production period is shortened, the unique magnetic field distribution design and the annular groove layout ensure that lead liquid is heated evenly, and the product quality problem caused by uneven temperature is effectively avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of lead-acid battery processing and production, and particularly relates to a heating and heat-preserving lead pot and its usage method. Background Art

[0002] In modern industrial production, lead is widely used in many fields such as battery manufacturing, cable sheaths, chemical corrosion prevention, and building materials. In these application scenarios, it is often necessary to heat lead blocks into lead liquid to meet the requirements of subsequent processing technologies such as casting and coating. During the entire processing process, as a key device, the performance of the heating and heat-preserving lead pot directly affects the quality of the lead liquid and the production efficiency.

[0003] Traditional heating and heat-preserving lead pots have exposed many problems in actual use. On the one hand, common heating methods such as resistance wire heating have low thermal efficiency and slow heating speed, resulting in high energy consumption and long production cycles. Moreover, this heating method is prone to uneven temperature distribution inside the lead pot, causing local overheating or insufficient heating of the lead liquid, which affects the quality stability of lead products. On the other hand, in terms of heat preservation, the heat preservation structure design of traditional lead pots is unreasonable, and heat loss is relatively fast. It is difficult to maintain the lead liquid at an appropriate working temperature for a long time, which not only increases the energy cost but also may cause the lead liquid to solidify, affecting the continuity of production.

[0004] With the continuous progress of industrial technology, higher requirements are put forward for the quality and production efficiency of lead products. At the same time, the concepts of environmental protection and energy conservation have become increasingly popular, prompting enterprises to search for more efficient, energy-saving, and environmentally friendly heating and heat-preserving equipment. Therefore, it is of great practical significance to develop a heating and heat-preserving lead pot and its usage method that can quickly and evenly heat lead blocks, effectively maintain the temperature of the lead liquid, and is energy-saving and environmentally friendly, which also plays a positive role in promoting the development of the lead processing industry. Summary of the Invention

[0005] Aiming at the existing technical problems, the present invention aims to provide a heating and heat-preserving lead pot and its usage method. By adopting electromagnetic induction heating technology, the heating and heat-preserving lead pot of the present invention can achieve rapid temperature rise, greatly improve the heating efficiency, and shorten the production cycle. The unique magnetic field distribution design and ring groove layout ensure uniform heating of the lead liquid, effectively avoiding product quality problems caused by uneven temperature. In terms of heat preservation, by setting up an auxiliary heating component to continuously heat the lead liquid, the temperature of the lead liquid can be always maintained stable, ensuring the continuity of production and the consistency of product quality.

[0006] To achieve the above object, the present invention provides the following technical solutions: A heating and heat-preserving lead pot, comprising a bracket, a lead pot, and a heat preservation and heating component; The bracket is arranged in a frame shape and bears and installs the lead pot; The lead pot is arranged in an upper and lower layered manner. The lead pot includes a heat preservation area located in the upper layer and a heating area located in the lower layer. The heat preservation area keeps the lead liquid warm, and the heating area is arranged in an inverted frustum shape and melts the lead block. The heat preservation and heating assembly performs heat preservation and heating treatments on the heat preservation area and the heating area respectively. The heat preservation and heating assembly includes a heating element, which is arranged around the outside of the heating area, and the heating element is a magnetic induction heating coil.

[0007] As an improvement, the wall thickness h of the heating area and the skin depth δ satisfy the relationship: 3.2δ > h > 3δ, where the skin depth δ = = , ρ is the resistivity of the conductor, ω is the angular frequency, ω = 2πf, f is the current frequency, μ is the magnetic permeability of the conductor, μ = μ0μ r , μ0 is the magnetic permeability of vacuum, μ0 = 4π×10 -7 H / m, μ r is the relative magnetic permeability.

[0008] As an improvement, a number of groups of circumferential annular grooves are convexly arranged inward on the side wall of the heating area, and rib strips are convexly arranged inward along the vertical direction on the side wall of the heating area.

[0009] As an improvement, a magnetic flux concentrator is arranged on the outside of the bottom of the heating area, and the magnetic flux concentrator is a U-shaped silicon steel sheet magnetic conductor.

[0010] As an improvement, the outside of the lead pot is wrapped with a heat preservation material, and the heat preservation material is at least one layer of aluminum foil or ceramic fiber blanket.

[0011] As an improvement, the heating element is wound along the depth direction of the heating area with a gradually expanding coil pitch, so that the density of turns of the heating element at the top of the heating area is less than the density of turns of the heating element at the bottom of the heating area.

[0012] As an improvement, an air gap is arranged between the heating element and the outer side wall of the heating area, and the distance h of the air gap and the diameter φ of the heating element satisfy the relationship: 1φ ≤ h ≤ 2φ; And the heating element is installed on the outside of the heating area through a support assembly.

[0013] As an improvement, the heating element adopts a copper tube embedded liquid cooling structure, and the coolant temperature is controlled at 30–50°C.

[0014] As an improvement, the heat preservation and heating assembly further includes a heat preservation element arranged in the heat preservation area. The heat preservation element is an electric heating wire, and the heat preservation element extends downward from the top of the heat preservation area and is inserted into the bottom of the heat preservation area.

[0015] In addition, the present invention also provides a method for using a heating and heat-preserving lead pot, which includes the following steps: Step 1: Put lead blocks. Open the lead pot and put the lead blocks to be melted into the heating area of the lead pot. Step 2: Start the heat-preserving heating component, connect the alternating current of the heating element. After the heating element is powered on, an alternating magnetic field is generated. This alternating magnetic field penetrates the side wall of the lead pot and acts on the heating area of the lead pot and the lead blocks inside. The alternating magnetic field generates an induced electromotive force in the conductor, and then induced currents are formed on the annular grooves and ribs inside the heating area. When the current passes through the annular grooves and ribs, heat is generated, and the lead blocks in the melting cavity start to be heated and melted into lead liquid. Step 3: Auxiliary heating and temperature maintenance. When the lead blocks start to melt, start the heat-preserving element arranged in the heat-preserving area to perform auxiliary heating and heat preservation on the lead liquid.

[0016] The beneficial effects of the present invention are as follows: (1) In the present invention, electromagnetic induction heating technology is adopted. By using the alternating magnetic field to generate induced current in the annular grooves, rapid temperature rise is realized. The heating efficiency is greatly improved compared with traditional resistance wire heating. Under the same heating conditions, it may take several hours to heat a certain amount of lead blocks to the required temperature using the traditional heating method, while the heating and heat-preserving lead pot of the present invention can complete it in a shorter time, greatly shortening the production cycle, improving the production efficiency, and meeting the requirements of large-scale industrial production for efficient processing. (2) In the present invention, by arranging circumferential annular grooves and vertical ribs on the side wall of the heating area, the heating efficiency, heating uniformity and structural stability can be significantly improved. This design not only optimizes heat conduction and eddy current distribution, but also enhances the mechanical strength of the heating area, enabling it to better adapt to high-temperature and high-pressure working environments. At the same time, the design of the annular grooves and ribs also helps to improve the energy utilization efficiency, reduce energy waste and extend the service life of the equipment. (3) In the present invention, the support component is installed on the installation base plate through support feet. The limiting part composed of its first limiting block and second limiting block can firmly limit the electromagnetic heating coil to prevent its displacement from affecting the heating effect. At the same time, the baffle is fixedly connected to the melting cavity, and the support columns and connecting blocks between the installation base plate and the baffle further ensure the stability of the overall structure of the lead pot and extend the service life of the equipment.

[0017] In summary, the present invention has the advantages of high-efficiency heating, uniform temperature, stable safety, convenient operation, etc., and is especially suitable for the technical field of lead-acid battery processing and production. Description of the Drawings

[0018] Figure 1 It is a schematic three-dimensional structure diagram of the whole lead pot of the present invention; Figure 2Schematic top view of the overall structure of the lead pot of the present invention; Figure 3 Schematic three-dimensional structure of the lead pot of the present invention; Figure 4 Schematic combined structure of the heating element and the support assembly of the present invention; Figure 5 Schematic three-dimensional structure of the support assembly and the magnetic flux concentrator of the present invention; Figure 6 Schematic diagram of the magnetic induction line distribution between the heating element and the annular groove of the present invention.

[0019] In the figure: bracket 1, lead pot 2, heat preservation area 21, heating area 22, annular groove 221, rib 222, magnetic flux concentrator 223, heat preservation and heating assembly 3, heating element 31, heat preservation element 32, support assembly 4, support foot 41, first limiting block 42, second limiting block 43, limiting part 44. Detailed implementation manners

[0020] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0021] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by terms such as "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be construed as a limitation to the present invention.

[0022] In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "a plurality" means two or more, unless otherwise specifically defined.

[0023] Embodiment 1: As Figures 1 to 6 shown, a heating and heat-preserving lead pot includes a bracket 1, a lead pot 2 and a heat preservation and heating assembly 3; The bracket 1 is arranged in a frame shape, and the bracket 1 bears and mounts the lead pot 2; The lead pot 2 is arranged in an upper and lower layered manner. The lead pot 2 includes a heat preservation area 21 located in the upper layer and a heating area 22 located in the lower layer. The heat preservation area 21 keeps the lead liquid warm to prevent the lead liquid from cooling too quickly. The heating area 22 is arranged in an inverted frustum shape, and this shape helps to concentrate heat and improve the hot melting efficiency. The heating area 22 melts the lead blocks; The heat preservation and heating assembly 3 performs heat preservation and heating treatments on the heat preservation area 21 and the heating area 22 respectively. The heat preservation and heating assembly 3 includes a heating element 31. The heating element 31 is arranged around the outside of the heating area 22, and the heating element 31 is a magnetic induction heating coil. The magnetic induction heating coil generates eddy currents through electromagnetic induction, thereby generating heat inside the lead blocks and melting them quickly. This heating method has the advantages of high efficiency, fast speed, and strong controllability.

[0024] Further, the wall thickness h of the heating area 22 and the skin depth δ satisfy the relationship: 3.2δ > h > 3δ. The wall thickness of the heating area 22 is large enough to enable the electromagnetic field to fully penetrate the conductor, thereby generating sufficient eddy current heating effect inside the heating area 22. The design of the wall thickness h also needs to consider the uniformity of heating. Too thick or too thin a wall may cause uneven temperature distribution inside the heating area 22, affecting the hot melting effect of the lead blocks. If the wall thickness is too thin h < 3δ, the electromagnetic field will penetrate the entire wall thickness and leak to the outside, resulting in reduced heating efficiency. If the wall thickness is too thick h > 3.2δ, it will cause the electromagnetic field outside the heating area 22 to be unable to effectively penetrate to the inside, resulting in energy waste and uneven heating. Too thick a wall will also increase the material cost and equipment weight. By controlling the wall thickness h within the range of 3.2δ > h > 3δ, it can be ensured that the electromagnetic field is fully distributed inside the heating area 22, achieving efficient and uniform heating effects.

[0025] Among them, the skin depth δ = = , where ρ is the resistivity of the conductor, ω is the angular frequency, ω = 2πf, f is the current frequency, μ is the magnetic permeability of the conductor, μ = μ0μ r , μ0 is the magnetic permeability of vacuum, μ0 = 4π×10 -7 H / m, μ r is the relative magnetic permeability.

[0026] Furthermore, several groups of circumferential annular grooves 221 are provided on the side wall of the heating zone 22 by inward convexity. The annular grooves 221 increase the surface area of the side wall of the heating zone 22, thereby improving the heat conduction efficiency and enabling the heat to be more evenly distributed into the lead block or lead liquid. The design of the annular grooves 221 can guide the electromagnetic field to form a more uniform eddy current distribution inside the heating zone 22, avoiding phenomena such as local overheating or insufficient heating. Moreover, the annular grooves 221 can relieve the stress generated by thermal expansion to a certain extent during the heating process, preventing the side wall from cracking or deforming; And ribs 222 are provided on the side wall of the heating zone 22 by inward convexity along the vertical direction. The height H of the ribs 222 and the wall thickness h of the heating zone 22 satisfy the relationship: h < H < h, avoiding stress concentration or fracture caused by the overly high ribs 222. The ribs 222 are arranged along the vertical direction, which can significantly enhance the mechanical strength of the side wall of the heating zone 22, preventing deformation or rupture in high-temperature and high-pressure environments. During the heating process, the ribs 222 can guide the flow of the lead liquid, avoiding the formation of dead zones of the lead liquid inside the heating zone 22, thereby improving the heating uniformity. And it can further increase the surface area of the side wall of the heating zone 22, enhancing the heat exchange efficiency and enabling the heat to be transferred to the lead block or lead liquid faster. The combined design of the annular grooves 221 and the ribs 222 can significantly improve the heating uniformity of the heating zone 22 while jointly enhancing the structural stability of the side wall of the heating zone 22, enabling it to withstand the stress brought by high temperature, high pressure, and thermal expansion. By increasing the heat exchange area and optimizing the eddy current distribution, the design of the annular grooves 221 and the ribs 222 can improve the energy utilization efficiency and reduce energy waste.

[0027] It should be noted that the ribs 222 and the annular grooves 221 are integrally formed with the lead pot 2 using the same material, with the same coefficient of thermal expansion, avoiding stress concentration and cracking problems caused by temperature changes. A titanium nitride coating is sprayed inside the lead pot 2 to enhance the lead corrosion resistance. The ribs 222, the annular grooves 221, and the lead pot 2 are integrally cast. Integral casting can eliminate the weak points brought by welding or splicing, improving the overall mechanical strength and durability of the lead pot 2.

[0028] In addition, a flux concentrator 223 is provided on the outer side of the bottom of the heating zone 22. The flux concentrator 223 can significantly improve the efficiency of magnetic induction heating, heating uniformity and energy utilization efficiency. It not only optimizes the distribution and penetration effect of the magnetic field, but also reduces energy loss, ensuring that the bottom of the heating zone 22 can uniformly and efficiently heat the lead block or lead liquid. The flux concentrator 223 is a U-shaped silicon steel sheet magnetic conductor. On the outer side of the bottom of the heating zone 22, the magnetic induction lines generated by the magnetic induction heating coil will preferentially pass through the silicon steel sheet with high magnetic permeability rather than air, forming a closed magnetic circuit, concentrating the magnetic field generated by the magnetic induction heating coil at the bottom of the heating zone 22. Through the concentrated magnetic field, the U-shaped silicon steel sheet magnetic conductor can make the magnetic field distribution at the bottom of the heating zone 22 more uniform, avoiding phenomena such as local overheating or insufficient heating. The U-shaped silicon steel sheet magnetic conductor also has good thermal management and mechanical strength, can adapt to high-temperature and high-pressure working environments, and extends the service life of the equipment.

[0029] It should be noted that since the flux concentrator 223 may generate a certain amount of heat under the action of the magnetic field, a small air gap needs to be maintained between the U-shaped silicon steel sheet magnetic conductor and the outer wall of the lead pot 2 to avoid deformation caused by direct contact with the high-temperature surface.

[0030] Furthermore, the outer side of the lead pot 2 is wrapped with a heat-insulating material, which is at least one layer of aluminum foil or ceramic fiber blanket. The heat-insulating material can effectively block heat conduction, convection and radiation, reduce the heat dissipation from the inside of the lead pot 2 to the external environment, thereby improving the heating efficiency and reducing energy consumption. Through heat insulation, the temperature inside the lead pot 2 can be more stable, avoiding temperature fluctuations caused by heat dissipation, and ensuring that the lead liquid or lead block is maintained within the required heating or heat-insulating temperature range.

[0031] Even further, the heating element 31 is wound along the depth direction of the heating zone 22 with an expanding coil pitch, so that the density of turns of the heating element 31 at the top of the heating zone 22 is less than the density of turns of the heating element 31 at the bottom of the heating zone 22. During the heating process of the lead pot 2, the temperature at the bottom of the heating zone 22 usually needs to be higher to quickly melt the solid lead block, while the temperature requirement at the top is relatively lower, mainly for heat insulation. The expanding coil pitch design makes the bottom coil denser, generating a stronger magnetic field and eddy current heating effect, while the top coil is sparser and the magnetic field is weaker, thus realizing the optimization of the temperature distribution. By increasing the turn density at the bottom, more magnetic field energy can be concentrated at the bottom of the heating zone 22, improving the heating efficiency and reducing the waste of energy at the top.

[0032] Among them, an air gap is provided between the heating element 31 and the outer sidewall of the heating zone 22. The existence of the air gap can adjust the magnetic field distribution between the heating element 31 and the heating zone 22, ensuring that the magnetic field can effectively penetrate the heating zone 22 to generate sufficient eddy current heating effect. An appropriate air gap can reduce the leakage of the magnetic field and improve the heating efficiency. The air gap can reduce the direct heat conduction between the heating element 31 and the heating zone 22, avoiding damage to the heating element 31 due to overheating; Meanwhile, the air gap also helps to reduce the temperature of the outer wall of the heating zone 22, improving the safety of the device. The distance h of the air gap and the diameter φ of the heating element 31 satisfy the relationship: 1φ ≤ h ≤ 2φ. This range is to balance the magnetic field distribution and the heating efficiency. If the air gap is too small, h < 1φ, the magnetic field may be too concentrated, resulting in uneven heating and increasing the thermal load of the heating element 31. If the air gap is too large, h > 2φ, too much magnetic field will leak, reducing the heating efficiency; And the heating element 31 is installed outside the heating zone 22 through a support assembly 4. The support assembly 4 includes support feet 41, a first limit block 42 and a second limit block 43. The support feet 41 are installed on the bracket 1. The support feet 41 are made of high-strength and wear-resistant materials. Both the first limit block 42 and the second limit block 43 are concave-shaped. The first limit block 42 and the second limit block 43 are connected relatively. This design can better fit the shape of the electromagnetic heating coil and also enhance the stability of the limit. There is a limit part 44 for accommodating the electromagnetic heating coil between the first limit block 42 and the second limit block 43. The electromagnetic heating coil passes through the limit part 44. The first limit block 42 and the second limit block 43 limit the electromagnetic heating coil from both sides, effectively preventing it from displacing in the horizontal direction. Moreover, the concave structure can also buffer the vibration generated during the operation of the device to a certain extent, avoiding damage to the electromagnetic heating coil due to vibration, ensuring the stable operation of the heating assembly 2, and further ensuring the efficient and continuous heating process of the lead block in the melting cavity 11 by the entire heating system.

[0033] Furthermore, the heating element 31 adopts a liquid-cooled structure with a copper tube embedded. The copper tube has excellent thermal conductivity and can quickly transfer the heat generated by the heating element 31 to the coolant, thus preventing the heating element 31 from overheating. The coolant temperature is controlled within the range of 30–50 °C, which can ensure that the heating element 31 operates at the optimal working temperature, avoiding performance degradation or damage caused by overheating. Through the liquid-cooled structure, the working temperature of the heating element 31 is stabilized, thereby ensuring the stability of its resistivity and magnetic induction heating efficiency. The coolant circulation can continuously take away the heat, avoiding the reduction of the heating efficiency of the heating element 31 due to too high temperature.

[0034] In addition, the heat preservation and heating assembly 3 further includes a heat preservation element 32 disposed in the heat preservation area 21. The heat preservation element 32 is an electric heating wire. By continuously heating, the heat preservation element 32 can compensate for the heat loss in the heat preservation area 21, ensuring that the lead liquid is maintained within the required temperature range. Moreover, the heat preservation element 32 extends downward from the top of the heat preservation area 21 and is inserted to the bottom of the heat preservation area 21, ensuring that the heating range covers the entire heat preservation area 21. This way can avoid the phenomenon of temperature stratification of the lead liquid in the heat preservation area 21. After the electric heating wire is powered on, it quickly converts electrical energy into heat energy, and the heat is quickly transferred to the inside of the melting cavity 11 through the surrounding air in the forms of thermal radiation and thermal convection. This not only effectively fills the temperature non-uniform area that may occur during the heating process of the heating assembly 2, making the upper and lower parts of the lead block heated more uniformly, but also greatly shortens the melting time of the lead block, significantly improving the production efficiency. By flexibly regulating the power of the electric heating wire, the refined control of the heating process can be realized, meeting the special requirements for the heating temperature, speed, etc. of the lead block in different production scenarios, and further optimizing the overall heating performance of the lead pot 2.

[0035] Embodiment 2: The present invention also provides a method for using a heating and heat-preserving lead pot based on the one described in Embodiment 1, including the following steps: Step 1: Place the lead block. Open the lead pot 2 and put the lead block to be melted into the heating area 22 of the lead pot 2. Step 2: Start the heat preservation and heating assembly 3. Connect the alternating current of the heating element 31. After the heating element 31 is powered on, it generates an alternating magnetic field. This alternating magnetic field penetrates the side wall of the lead pot 2 and acts on the heating area 22 of the lead pot 2 and the lead block inside. The alternating magnetic field generates an induced electromotive force in the conductor, and then forms an induced current on the annular groove 221 and the rib 222 inside the heating area 22. When the current passes through the annular groove 221 and the rib 222, heat will be generated, and the lead block in the melting cavity 11 will start to be heated and melted into lead liquid. Step 3: Auxiliary heating and temperature maintenance. When the lead block starts to melt, start the heat preservation element 32 disposed in the heat preservation area 21 to perform auxiliary heating and heat preservation on the lead liquid.

[0036] It should be noted that eddy currents are generated in the conductor lead block and the side wall of the heating area 22 by the alternating magnetic field, and the eddy currents generate heat through resistance, thereby realizing efficient heating.

[0037] It should be further noted that when the electromagnetic induction phenomenon occurs, the alternating magnetic field generated by the electromagnetic heating coil is distributed and extended to the space on both sides centered on the annular groove 221.

[0038] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention should be included within the protection scope of the present invention.

Claims

1. A heating and heat-preserving lead pot, characterized in that: It includes a bracket (1), a lead pot (2) and a heat-preserving and heating component (3); The bracket (1) is arranged in a frame shape, and the bracket (1) bears and installs the lead pot (2); The lead pot (2) is arranged in an upper and lower layered manner. The lead pot (2) includes a heat-preserving area (21) located in the upper layer and a heating area (22) located in the lower layer. The heat-preserving area (21) keeps the lead liquid warm, and the heating area (22) is arranged in an inverted frustum shape, and the heating area (22) melts the lead block; The heat-preserving and heating component (3) performs heat-preserving and heating treatments on the heat-preserving area (21) and the heating area (22) respectively. The heat-preserving and heating component (3) includes a heating element (31), and the heating element (31) is arranged around the outside of the heating area (22), and the heating element (31) is a magnetic induction heating coil.

2. The heating and heat-preserving lead pot according to claim 1, characterized in that: The wall thickness h of the heating zone (22) and the skin depth δ satisfy the relationship: 3.2δ > h > 3δ, where the skin depth δ = = , ρ is the resistivity of the annular groove, ω is the angular frequency, ω = 2πf, f is the current frequency, μ is the magnetic permeability of the annular groove, μ = μ0μ r , μ0 is the magnetic permeability of vacuum, μ0 = 4π×10 -7 H / m, μ r is the relative magnetic permeability.

3. The heating and heat-preserving lead pot according to claim 1, characterized in that: A number of groups of circumferential annular grooves (221) are convexly arranged inward on the side wall of the heating area (22), and ribs (222) are convexly arranged inward along the vertical direction on the side wall of the heating area (22).

4. The heating and heat-preserving lead pot according to claim 1, characterized in that: A magnetic flux concentrator (223) is arranged on the outside of the bottom of the heating area (22), and the magnetic flux concentrator (223) is a U-shaped silicon steel sheet magnetic conductor.

5. The heating and heat-preserving lead pot according to claim 1, characterized in that: The outside of the lead pot (2) is wrapped with a heat-preserving material, and the heat-preserving material is at least one layer of aluminum foil or ceramic fiber blanket.

6. The heating and heat-preserving lead pot according to claim 1, characterized in that: The heating element (31) is wound along the depth direction of the heating area (22) with a gradually expanding coil spacing, so that the density of turns of the heating element (31) at the top of the heating area (22) is less than the density of turns of the heating element (31) at the bottom of the heating area (22).

7. The heating and heat-preserving lead pot according to claim 1, characterized in that: An air gap is arranged between the heating element (31) and the outer side wall of the heating area (22), and the distance h of the air gap and the diameter φ of the heating element (31) satisfy the relationship: 1φ≤h≤2φ; And the heating element (31) is installed on the outside of the heating area (22) through a support assembly (4).

8. The heating and heat-preserving lead pot according to claim 1, characterized in that: The heating element (31) adopts a liquid-cooling structure with a copper tube embedded type, and the coolant temperature is controlled at 30–50°C.

9. The heating and heat-preserving lead pot according to claim 1, characterized in that: The heat-preserving and heating component (3) further includes a heat-preserving element (32) arranged in the heat-preserving area (21). The heat-preserving element (32) is an electric heating wire, and the heat-preserving element (32) extends downward from the top of the heat-preserving area (21) and is inserted into the bottom of the heat-preserving area (21).

10. A method for using a heating and heat-preserving lead pot according to any one of claims 1-9, characterized in that, It includes the following steps: Step 1: Place lead blocks. Open the lead pot and put the lead blocks to be melted into the heating area (22) of the lead pot (2). Step 2: Start the heat preservation heating component. Connect the alternating current of the heating element (31). After the heating element (31) is powered on, an alternating magnetic field is generated. This alternating magnetic field penetrates the side wall of the lead pot (2) and acts on the heating area (22) of the lead pot (2) and the lead blocks inside. The alternating magnetic field generates an induced electromotive force in the annular groove (221), and then an induced current is formed on the annular groove (221) and the rib (222) inside the heating area (22). When the current passes through the annular groove (221) and the rib (222), heat is generated, and the lead blocks in the melting cavity (11) start to be heated and melted into lead liquid. Step 3: Auxiliary heating and temperature maintenance. When the lead blocks start to melt, start the heat preservation element (32) arranged in the heat preservation area (21) to perform auxiliary heating and heat preservation on the lead liquid.

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