Induction coil for medium-frequency electric furnace and medium-frequency electric furnace

Abstract

The utility model relates to the technical field of metallurgical electric furnaces, in particular to an induction coil for a medium-frequency electric furnace, which comprises an induction heating coil, an upper cooling coil positioned above the induction heating coil and a lower cooling coil positioned below the induction heating coil, the upper cooling coil, the induction heating coil and the lower cooling coil are all formed by winding hollow pipe bodies in the same spiral direction, the cross section of the induction heating coil is in a D shape, and the induction heating coil comprises an inner pipe wall, an outer pipe wall and two connecting walls connected between the inner pipe wall and the outer pipe wall. The cross section of the induction heating coil is designed to be D-shaped, the inner pipe wall located on the inner side of the induction heating coil is arranged to be arc-shaped, and the outer pipe wall located on the outer side of the induction heating coil extends in the vertical direction, so that current and magnetic field distribution is optimized, and magnetic field energy acts on the surface of a workpiece on the inner side of the induction heating coil more intensively; energy loss is reduced, the heating speed of workpieces is increased, and the heating efficiency of the medium-frequency electric furnace is improved.

Description

Technical Field

[0001] This utility model relates to the field of metallurgical electric furnace technology, specifically to an induction coil for a medium-frequency electric furnace and a medium-frequency electric furnace. Background Technology

[0002] An intermediate frequency furnace is a power supply device that converts 50Hz AC power into intermediate frequency (300Hz to 1000Hz) power. It rectifies three-phase AC power into DC power, then converts the DC power into adjustable intermediate frequency current, supplying this current to a capacitor and an induction coil. This generates an alternating magnetic field around the induction coil, which cuts the metal workpiece placed inside the coil. Large eddy currents are generated within the metal workpiece, heating or melting it using the induction heating effect. The performance of the induction coil directly affects the heating effect of the intermediate frequency furnace. In existing technologies, the induction coil is often formed by winding multiple hollow tubes, which are regular rectangles or circles. This results in a relatively uniform distribution of magnetic field energy between the inside and outside of the induction coil, leading to greater energy loss, poorer heating of the workpiece, and lower heating efficiency. Utility Model Content

[0003] The purpose of this invention is to provide an induction coil for a medium-frequency electric furnace and a medium-frequency electric furnace with high heating efficiency, so as to overcome the problems existing in the existing equipment.

[0004] To achieve the above objectives, the technical solution adopted by this utility model is as follows: an induction coil for a medium-frequency electric furnace, comprising an induction heating coil, an upper cooling coil located above the induction heating coil, and a lower cooling coil located below the induction heating coil. The upper cooling coil is used to cool the furnace opening of the medium-frequency electric furnace, and the lower cooling coil is used to cool the furnace bottom of the medium-frequency electric furnace. The upper cooling coil, the induction heating coil, and the lower cooling coil are all formed by winding hollow tubes in the same spiral direction. The hollow tubes are filled with cooling water. The cross-section of the induction heating coil is D-shaped, including an inner tube wall, an outer tube wall, and two connecting walls connecting the inner tube wall and the outer tube wall. The inner tube wall is arc-shaped and located inside the spirally wound induction heating coil, and the outer tube wall extends vertically and is located outside the spirally wound induction heating coil.

[0005] Based on the above technical solution, the present invention can be further improved as follows:

[0006] As a further improvement to the above technical solution, the hollow tube is a copper tube made of purple copper material through extrusion, the cross-section of the upper cooling coil and the lower cooling coil is circular, and the wall thickness of the induction heating coil is uniform.

[0007] As a further improvement to the above technical solution, the connecting wall of the induction heating coil extends horizontally, the outer surface of the connecting wall is a horizontal plane, the outer surface of the inner tube wall is an arc surface, the outer surface of the outer tube wall is a vertical plane, the outer surface of the connecting wall is connected between the outer surface of the inner tube wall and the outer surface of the outer tube wall, and an arc-shaped surface is provided between the outer surface of the connecting wall and the outer surface of the outer tube wall.

[0008] As a further improvement to the above technical solution, the upper cooling coil is provided with a first connector and a second connector at both ends, the induction heating coil is provided with a third connector and a fourth connector at both ends, and the lower cooling coil is provided with a fifth connector and a sixth connector at both ends; the first connector, the third connector and the fifth connector are used to connect to cooling water, and the second connector, the fourth connector and the sixth connector are used to disconnect cooling water; the outer walls of the third connector and the fourth connector are used to connect to an AC power source.

[0009] As a further improvement to the above technical solution, the third connector extends downward and then horizontally to form a first connecting pipe, and the fourth connector extends horizontally to form a second connecting pipe. Both the first and second connecting pipes are provided with power connection copper parts, which are used to connect to AC power. Both the first and second connecting pipes are connected to the middle section of the induction heating coil except for the two ends through water cooling pipes.

[0010] As a further improvement to the above technical solution, both the upper cooling coil and the lower cooling coil include two-turn coils, and the induction heating coil includes multiple-turn coils. In the axial direction of the induction coil, the spacing between each turn of the induction heating coil is equal.

[0011] This utility model also provides a medium-frequency electric furnace, including a furnace shell, the aforementioned induction coil, and a plurality of insulating rods. The induction coil is installed inside the furnace shell, and the plurality of insulating rods are fixed to the induction coil.

[0012] As a further improvement to the above technical solution, the furnace shell is made of stainless steel and includes a furnace shell body, a furnace shell top cover, and a furnace shell base.

[0013] As a further improvement to the above technical solution, the insulating rod is located outside the induction coil, and the insulating rods are evenly distributed at intervals in the circumferential direction outside the induction coil; the insulating rods are connected to the induction coil by bolts, and the insulating rods are all arranged along the axial direction of the induction coil.

[0014] The beneficial effects of this utility model are as follows: The induction coil for medium-frequency electric furnace provided by this utility model has a D-shaped cross-section, an arc-shaped inner tube wall located inside the induction heating coil, and an outer tube wall extending vertically outside the induction heating coil. This optimizes the distribution of current and magnetic field, so that the magnetic field energy is more concentrated on the surface of the workpiece inside the induction heating coil, reducing energy loss and accelerating the heating speed of the workpiece, thereby improving the heating efficiency of the medium-frequency electric furnace. Attached Figure Description

[0015] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0016] Figure 1 This is a schematic diagram of the structure of the medium-frequency electric furnace provided in a preferred embodiment of the present invention;

[0017] Figure 2 yes Figure 1 A schematic diagram of the structure of the induction coil used in the medium-frequency electric furnace;

[0018] Figure 3 yes Figure 2 A top view of the induction coil used in the medium-frequency electric furnace;

[0019] Figure 4 yes Figure 2 A cross-sectional view of the induction coil used in a medium-frequency electric furnace;

[0020] In the diagram: 10. Induction coil; 11. Upper cooling coil; 111. First connector; 112. Second connector; 12. Induction heating coil; 121. Third connector; 122. Fourth connector; 123. Inner tube wall; 124. Outer tube wall; 125. Connecting wall; 126. First connecting pipe; 127. Second connecting pipe; 128. Power connection copper part; 13. Lower cooling coil; 131. Fifth connector; 132. Sixth connector; 20. Furnace shell; 21. Furnace shell body; 22. Furnace shell top cover; 23. Furnace shell base; 30. Insulating rod. Detailed Implementation

[0021] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. These drawings are simplified schematic diagrams, which are only used to illustrate the basic structure of the present invention in a schematic manner, and therefore only show the components related to the present invention.

[0022] In the description of this utility model, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing this utility model and simplifying the description, and do not 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 this utility model. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this utility model, unless otherwise stated, "a plurality of" means two or more.

[0023] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0024] like Figures 1 to 4 As shown, a preferred embodiment of this utility model provides an induction coil 10 for a medium-frequency electric furnace, including an induction heating coil 12, an upper cooling coil 11 located above the induction heating coil 12, and a lower cooling coil 13 located below the induction heating coil 12. The upper cooling coil 11, the induction heating coil 12, and the lower cooling coil 13 are arranged sequentially at intervals. The upper cooling coil 11, the induction heating coil 12, and the lower cooling coil 13 are all formed by winding hollow tubes in the same spiral direction. The cross-sections of the upper cooling coil 11 and the lower cooling coil 13 are circular, and the cross-section of the induction heating coil 12 is D-shaped, including an inner tube wall 123, an outer tube wall 124, and two connecting walls 125 connecting the inner tube wall 123 and the outer tube wall 124. The inner tube wall 123 is arc-shaped and located inside the spirally wound induction heating coil 12, and the outer tube wall 124 extends vertically and is located outside the spirally wound induction heating coil 12.

[0025] The upper cooling coil 11 is used to cool the furnace mouth of the medium-frequency electric furnace, and the lower cooling coil 13 is used to cool the furnace bottom. No current flows through the upper cooling coil 11 and the lower cooling coil 13. The induction heating coil 12 is both energized and circulated with water. The hollow tube is filled with cooling water, which flows inside the upper cooling coil 11, the induction heating coil 12, and the lower cooling coil 13 to dissipate heat. The induction heating coil 12 has a D-shaped cross-section. The uniform wall thickness design of the D-shaped cross-section reduces resistance loss while ensuring the structural strength of the induction heating coil 12.

[0026] Furthermore, the connecting wall 125 extends horizontally and connects the inner tube wall 123 and the outer tube wall 124. The outer surface of the connecting wall 125 is a horizontal plane, the outer surface of the inner tube wall 123 is an arc surface, the outer tube wall 124 extends vertically and is located in a vertical plane, and the outer surface of the outer tube wall 124 is a vertical plane. The outer surface of the connecting wall 125 connects the outer surface of the inner tube wall 123 and the outer surface of the outer tube wall 124, and an arc surface is provided between the outer surface of the connecting wall 125 and the outer surface of the outer tube wall 124. Thus, the outer surface of the induction heating coil 12 transitions between the horizontal plane and the vertical plane through an arc surface, preventing the induction heating coil 12 from arcing and tip discharge.

[0027] Furthermore, the upper cooling coil 11 has a first connector 111 and a second connector 112 at both ends, the induction heating coil 12 has a third connector 121 and a fourth connector 122 at both ends, and the lower cooling coil 13 has a fifth connector 131 and a sixth connector 132 at both ends. The first connector 111, the third connector 121, and the fifth connector 131 are used to connect to cooling water, and the second connector 112, the fourth connector 122, and the sixth connector 132 are used to discharge cooling water; the outer walls of the third connector 121 and the fourth connector 122 are used to connect to an AC power source.

[0028] Furthermore, the third connector 121 extends downwards and then horizontally to form a first connecting pipe 126, and the fourth connector 122 extends horizontally to form a second connecting pipe 127. Both the first connecting pipe 126 and the second connecting pipe 127 are provided with power connection copper parts 128 for connection to an AC power source. Both the first connecting pipe 126 and the second connecting pipe 127 are connected to the middle section of the induction heating coil 12 (excluding both ends) via water-cooling pipes (not shown), allowing cooling water to flow within the induction heating coil 12, the first connecting pipe 126, and the second connecting pipe 127 for heat dissipation.

[0029] Understandably, the hollow tube is made of metal and has good electrical and thermal conductivity; preferably, the hollow tube is a copper tube made of copper material through extrusion.

[0030] Furthermore, both the upper cooling coil 11 and the lower cooling coil 13 include two turns, and the induction heating coil 12 includes multiple turns. In the axial direction of the induction coil 10, the spacing between each turn of the induction heating coil 12 is equal. By providing a larger number of turns in the induction heating coil 12, the heating effect of the induction heating coil 12 is ensured. Simultaneously, the induction heating coil 12 is made by winding the same hollow tube without any joints, thus avoiding magnetic leakage, improving the heating effect, and reducing energy consumption.

[0031] In addition, a preferred embodiment of this utility model also provides a medium-frequency electric furnace, including a furnace shell 20, an induction coil 10 installed inside the furnace shell 20, and a plurality of insulating rods 30 fixed to the induction coil 10. The furnace shell 20 is made of stainless steel, which has poor magnetic conductivity. The furnace shell 20 includes a furnace shell body 21, a furnace shell top cover 22, and a furnace shell base 23.

[0032] The insulating rods 30 are all arranged along the axial direction of the induction coil 10, and each coil turn is connected to each insulating rod 30 to fix the spacing of each coil turn and prevent the position of each coil turn from shifting during use. Furthermore, the insulating rods 30 are located outside the induction coil 10, and are evenly distributed at intervals along the circumferential direction outside the induction coil 10. Furthermore, the insulating rods 30 are connected to the induction coil 10 by bolts to facilitate the disassembly and maintenance of the induction coil 10.

[0033] In this embodiment, the inner diameter of the winding induction coil 10 is set to 480mm, the outer diameter to 530mm, the spacing between each turn of the induction heating coil 12 is set to 15mm, and the height of the insulating rod 30 is set to 800mm. After the coil is polished, insulating varnish is sprayed on it, and then arc-extinguishing varnish is sprayed on the whole coil. After the medium-frequency electric furnace is assembled, it is tested for leakage at 0.6MPa water pressure for 1 hour to ensure that no leakage occurs.

[0034] In use, the workpiece to be melted is placed inside the induction coil 10. When the induction heating coil 12 is energized with alternating current, the inner tube wall 123 inside the induction heating coil 12 is set in an arc shape, and the outer tube wall 124 outside the induction heating coil 12 extends vertically. According to the current loop effect, the electromagnetic field formed by the alternating current in the induction heating coil 12 is concentrated inside the induction heating coil 12, so that the current density of the inner tube wall 123 inside the induction heating coil 12 is significantly higher than the current density of the outer tube wall 124 outside the induction heating coil 12. In this way, the magnetic field energy is more concentrated on the surface of the workpiece inside the induction heating coil 12, reducing energy loss and accelerating the heating speed of the workpiece, thereby improving the heating efficiency of the medium frequency electric furnace.

[0035] The induction coil 10 for medium-frequency electric furnace provided by this utility model optimizes the distribution of current and magnetic field by designing the cross-section of the induction heating coil 12 as D-shaped, setting the inner tube wall 123 located inside the induction heating coil 12 as arc-shaped, and setting the outer tube wall 124 outside the induction heating coil 12 as extending in the vertical direction. In this way, the magnetic field energy is more concentrated on the surface of the workpiece inside the induction heating coil 12, reducing energy loss and accelerating the heating speed of the workpiece, thereby improving the heating efficiency of the medium-frequency electric furnace.

[0036] Any descriptions not covered in the above specific embodiments of this utility model belong to the well-known technology in the field, and can be implemented by referring to the well-known technology.

[0037] Based on the preferred embodiments of this utility model described above, those skilled in the art can make various changes and modifications without departing from the technical concept of this utility model. The technical scope of this utility model is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. An induction coil for a medium-frequency electric furnace, characterized in that: The system includes an induction heating coil, an upper cooling coil located above the induction heating coil, and a lower cooling coil located below the induction heating coil. The upper cooling coil is used to cool the furnace opening of the medium-frequency electric furnace, and the lower cooling coil is used to cool the furnace bottom of the medium-frequency electric furnace. The upper cooling coil, the induction heating coil, and the lower cooling coil are all formed by winding hollow tubes in the same spiral direction. The hollow tubes are filled with cooling water. The cross-section of the induction heating coil is D-shaped, including an inner tube wall, an outer tube wall, and two connecting walls connecting the inner tube wall and the outer tube wall. The inner tube wall is arc-shaped and located inside the spirally wound induction heating coil, while the outer tube wall extends vertically and is located outside the spirally wound induction heating coil.

2. The induction coil for a medium-frequency electric furnace according to claim 1, characterized in that: The hollow tube is a copper tube made of purple copper through extrusion. The upper and lower cooling coils have circular cross-sections, and the induction heating coil has a uniform wall thickness.

3. The induction coil for a medium-frequency electric furnace according to claim 1, characterized in that: The connecting wall of the induction heating coil extends horizontally. The outer surface of the connecting wall is a horizontal plane, the outer surface of the inner tube wall is an arc surface, and the outer surface of the outer tube wall is a vertical plane. The outer surface of the connecting wall is connected between the outer surface of the inner tube wall and the outer surface of the outer tube wall, and an arc-shaped surface is provided between the outer surface of the connecting wall and the outer surface of the outer tube wall.

4. The induction coil for a medium-frequency electric furnace according to claim 3, characterized in that: The upper cooling coil has a first connector and a second connector at both ends, the induction heating coil has a third connector and a fourth connector at both ends, and the lower cooling coil has a fifth connector and a sixth connector at both ends; the first connector, the third connector and the fifth connector are used to connect to cooling water, and the second connector, the fourth connector and the sixth connector are used to disconnect cooling water; the outer walls of the third connector and the fourth connector are used to connect to an AC power source.

5. The induction coil for a medium-frequency electric furnace according to claim 4, characterized in that: The third connector extends downwards and then horizontally to form the first connecting pipe, and the fourth connector extends horizontally to form the second connecting pipe. Both the first and second connecting pipes are provided with power connection copper parts, which are used to connect to AC power. Both the first and second connecting pipes are connected to the middle section of the induction heating coil except for the two ends through water cooling pipes.

6. The induction coil for a medium-frequency electric furnace according to claim 1, characterized in that: Both the upper cooling coil and the lower cooling coil include two turns of coil, and the induction heating coil includes multiple turns of coil. In the axial direction of the induction coil, the spacing between each turn of the induction heating coil is equal.

7. A medium-frequency electric furnace, characterized in that: It includes a furnace shell, an induction coil as described in any one of claims 1-6, and a plurality of insulating rods, wherein the induction coil is installed inside the furnace shell and the plurality of insulating rods are fixed to the induction coil.

8. The medium-frequency electric furnace according to claim 7, characterized in that: The furnace shell is made of stainless steel and includes a furnace shell body, a furnace shell top cover, and a furnace shell base.

9. The medium-frequency electric furnace according to claim 8, characterized in that: The insulating rods are located outside the induction coil, and are evenly distributed at intervals along the circumferential direction outside the induction coil. The insulating rods are connected to the induction coil by bolts, and are all arranged along the axial direction of the induction coil.

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