JP7415362B2 - induction furnace - Google Patents

induction furnace Download PDF

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JP7415362B2
JP7415362B2 JP2019142468A JP2019142468A JP7415362B2 JP 7415362 B2 JP7415362 B2 JP 7415362B2 JP 2019142468 A JP2019142468 A JP 2019142468A JP 2019142468 A JP2019142468 A JP 2019142468A JP 7415362 B2 JP7415362 B2 JP 7415362B2
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coil
conductive layer
yoke
induction furnace
conductive
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JP2021025679A (en
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秀好 増井
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Fuji Electric Co Ltd
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Fuji Electric Co Ltd
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B14/00—Crucible or pot furnaces
    • F27B14/06—Crucible or pot furnaces heated electrically, e.g. induction crucible furnaces with or without any other source of heat
    • F27B14/061—Induction furnaces
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B6/00—Heating by electric, magnetic or electromagnetic fields
    • H05B6/02—Induction heating
    • H05B6/36—Coil arrangements
    • H05B6/365—Coil arrangements using supplementary conductive or ferromagnetic pieces
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B6/00—Heating by electric, magnetic or electromagnetic fields
    • H05B6/02—Induction heating
    • H05B6/36—Coil arrangements
    • H05B6/367—Coil arrangements for melting furnaces
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/25—Process efficiency

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Crucibles And Fluidized-Bed Furnaces (AREA)
  • Furnace Details (AREA)
  • General Induction Heating (AREA)

Description

本発明は、るつぼで被加熱材を加熱する誘導炉に関する。 The present invention relates to an induction furnace that heats a material to be heated in a crucible.

るつぼの外周にコイルが巻回された誘導炉が知られている。コイルには高周波で高電圧の交流が印加されて電磁誘導を発生させ、るつぼに収容された被加熱材の内部に渦電流を生じさせ効率良く熔解させることができる。被加熱材は例えば金属溶融である。るつぼは金属溶融以外への熱伝導を抑制している。コイルは絶縁被覆や絶縁板などの絶縁物で絶縁されている。 Induction furnaces are known in which a coil is wound around the outer periphery of a crucible. A high-frequency, high-voltage alternating current is applied to the coil to generate electromagnetic induction, which generates an eddy current inside the material to be heated housed in the crucible, thereby making it possible to efficiently melt the material. The material to be heated is, for example, metal melting. The crucible suppresses heat conduction to areas other than metal melting. The coil is insulated with an insulating material such as an insulating coating or an insulating plate.

このような誘導炉としては、例えば特許文献１に記載のものが挙げられる。特許文献１に記載の誘導炉は、真空容器中で使用される小型のものである。一方、大型の誘導炉の場合にはコイルを外周側から保持するために継鉄が用いられる。継鉄は接地されている。 An example of such an induction furnace is the one described in Patent Document 1. The induction furnace described in Patent Document 1 is a small-sized one used in a vacuum container. On the other hand, in the case of a large induction furnace, a yoke is used to hold the coil from the outer circumferential side. The yoke is grounded.

特開平１０－９２５６６号公報Japanese Patent Application Publication No. 10-92566

誘導炉は一層の大容量化および高効率化が望まれている。高効率化を実現するためには、コイルの印加電圧を上昇させてその分電流を低下させればコイルの発熱を抑制させることができて好適である。 Induction furnaces are desired to have even larger capacity and higher efficiency. In order to achieve high efficiency, it is preferable to increase the voltage applied to the coil and reduce the current accordingly, since heat generation in the coil can be suppressed.

コイルに印加できる電圧はコイルの絶縁物の性能と厚みとによってほぼ決まる。しかしながら従来の構成では、良質の絶縁物を相当に厚く形成しても、絶縁物の端部や継鉄の端部に電界集中が発生している。このため、コイルの印加電圧が過大であると継鉄とコイルとの間で部分放電が発生して絶縁物が劣化し全路破壊が発生する懸念がある。本願発明者の実験によれば１０ｋＶ以上の電圧をコイルに印加するとこのような放電が発生する可能性がある。したがって、従来の誘導炉ではコイル印加電圧が概ね５ｋＶ程度に制限されており、一層の高圧化が望まれている。 The voltage that can be applied to the coil is largely determined by the performance and thickness of the coil's insulation. However, in the conventional configuration, even if a high-quality insulator is formed to be considerably thick, electric field concentration occurs at the ends of the insulator and the ends of the yoke. For this reason, if the voltage applied to the coil is excessive, there is a concern that partial discharge will occur between the yoke and the coil, causing deterioration of the insulator and total circuit breakdown. According to experiments conducted by the inventor of the present application, such discharge may occur when a voltage of 10 kV or more is applied to the coil. Therefore, in conventional induction furnaces, the voltage applied to the coil is generally limited to about 5 kV, and higher voltages are desired.

本発明は、上記の課題に鑑みてなされたものであって、コイルに対する印加電圧を一層上昇させることのできる誘導炉を提供することを目的とする。 The present invention has been made in view of the above problems, and an object of the present invention is to provide an induction furnace that can further increase the voltage applied to the coil.

上述した課題を解決し、目的を達成するために、本発明にかかる誘導炉は、被加熱材を収納するるつぼと、前記るつぼの外周に巻回され、絶縁被覆を有するコイルと、前記コイルの外周面を覆う導電層と、前記導電層を介して前記コイルを外周側から保持する継鉄と、を備え、前記導電層および前記継鉄は接地されていることを特徴とする。 In order to solve the above-mentioned problems and achieve the objects, an induction furnace according to the present invention includes: a crucible that stores a material to be heated; a coil that is wound around the outer periphery of the crucible and has an insulating coating; It is characterized in that it includes a conductive layer that covers an outer peripheral surface, and a yoke that holds the coil from the outer peripheral side via the conductive layer, and the conductive layer and the yoke are grounded.

前記導電層は導電性樹脂または導電性接着剤であり、前記コイルの絶縁被覆と密着していてもよい。 The conductive layer is a conductive resin or a conductive adhesive, and may be in close contact with the insulating coating of the coil.

前記導電層と前記コイルとの間には絶縁シートが設けられていてもよい。 An insulating sheet may be provided between the conductive layer and the coil.

前記導電層と前記継鉄の間に導電性の緩衝材を備え、前記導電層は、前記緩衝材および前記継鉄を介して接地されていてもよい。 A conductive buffer material may be provided between the conductive layer and the yoke, and the conductive layer may be grounded via the buffer material and the yoke.

前記コイルの導線は断面が角型であってもよい。 The conductive wire of the coil may have a rectangular cross section.

本発明にかかる誘導炉は、コイルの絶縁被覆に加わる電界を均一化させて部分放電の発生を抑制することができる。これによりコイルに対する印加電圧を一層上昇させることができる。 The induction furnace according to the present invention can suppress the occurrence of partial discharge by uniformizing the electric field applied to the insulating coating of the coil. This allows the voltage applied to the coil to be further increased.

図１は、実施の形態にかかる誘導炉を示す側面模式断面図である。FIG. 1 is a schematic side sectional view showing an induction furnace according to an embodiment. 図２は、誘導炉の模式平面図である。FIG. 2 is a schematic plan view of the induction furnace. 図３は、コイルおよびその周辺部の一部拡大断面図である。FIG. 3 is a partially enlarged sectional view of the coil and its surrounding area. 図４は、誘導炉における継鉄の周辺で発生する電界強度の解析結果を示す図であり、（ａ）は比較例１にかかる誘導炉における電界強度の解析結果を示す図であり、（ｂ）は比較例２にかかる誘導炉における電界強度の解析結果を示す図であり、（ｃ）は実施形態と類似の誘導炉における電界の解析結果を示す図である。FIG. 4 is a diagram showing the analysis results of the electric field strength generated around the yoke in the induction furnace, (a) is a diagram showing the analysis result of the electric field strength in the induction furnace according to Comparative Example 1, and (b) ) is a diagram showing the analysis result of the electric field strength in the induction furnace according to Comparative Example 2, and (c) is a diagram showing the analysis result of the electric field in the induction furnace similar to the embodiment.

以下に、本発明にかかる誘導炉の実施形態を図面に基づいて詳細に説明する。なお、この実施形態によりこの発明が限定されるものではない。 EMBODIMENT OF THE INVENTION Below, embodiment of the induction furnace concerning this invention is described in detail based on drawing. Note that the present invention is not limited to this embodiment.

図１は、本発明の実施形態である誘導炉１０を示す側面模式断面図であり、図２は、誘導炉１０の模式平面図である。 FIG. 1 is a schematic side sectional view showing an induction furnace 10 according to an embodiment of the present invention, and FIG. 2 is a schematic plan view of the induction furnace 10.

図１および図２に示すように、誘導炉１０は、被加熱材１２を収納するるつぼ１４と、るつぼ１４の外周に巻回された誘導加熱用のコイル１６と、コイル１６の外周を覆う導電層１８と、導電層１８の外周を覆う緩衝材２０と、導電層１８および緩衝材２０を介してコイル１６を外周側から保持する継鉄２２とを備える。るつぼ１４、コイル１６、導電層１８、緩衝材２０および継鉄２２は下部キャスタブル２４の上に設置されている。誘導炉１０は全体が導電性の筐体２６で覆われており、該筐体２６はアース線２８で接地されている。継鉄２２は筐体２６と接しており、該筐体２６を介して接地されている。また、後述するように、導電層１８は緩衝材２０および継鉄２２を介して接地されている。筐体２６は破線で示している。 As shown in FIGS. 1 and 2, the induction furnace 10 includes a crucible 14 that stores a material to be heated 12, a coil 16 for induction heating wound around the outer periphery of the crucible 14, and a conductive coil 16 that covers the outer periphery of the coil 16. layer 18, a buffer material 20 that covers the outer periphery of the conductive layer 18, and a yoke 22 that holds the coil 16 from the outer circumferential side via the conductive layer 18 and the buffer material 20. The crucible 14 , the coil 16 , the conductive layer 18 , the buffer material 20 and the yoke 22 are installed on the lower castable 24 . The induction furnace 10 is entirely covered with a conductive casing 26, and the casing 26 is grounded by a ground wire 28. The yoke 22 is in contact with a housing 26 and is grounded via the housing 26. Furthermore, as will be described later, the conductive layer 18 is grounded via a buffer material 20 and a yoke 22. The housing 26 is shown in broken lines.

誘導炉１０は大型であり、コイル１６を保持するために継鉄２２が設けられている。ただし、誘導炉１０の構造を小型のものに適用してもよい。誘導炉１０は全体を傾斜させることにより、るつぼ１４内の被加熱材１２の取出しが可能である。誘導炉１０は空気中に設置される。誘導炉１０は、交番磁界中に溶解される被加熱材１２を収容し、電磁誘導によって被加熱材に渦電流を流して誘導加熱し熔解し金属溶湯を得る。 The induction furnace 10 is large and is provided with a yoke 22 to hold the coil 16. However, the structure of the induction furnace 10 may be applied to a small-sized one. By tilting the entire induction furnace 10, the material to be heated 12 in the crucible 14 can be taken out. The induction furnace 10 is installed in the air. The induction furnace 10 accommodates a material to be heated 12 to be melted in an alternating magnetic field, and by electromagnetic induction, an eddy current is passed through the material to be heated to induce induction heating and melting to obtain a molten metal.

導電層１８はコイル１６の下端部から上端部まで外側の全周を覆う。導電層１８は、例えばカーボンなどを含む導電性樹脂または導電性接着剤であり、コイル１６の導線３０（図３参照）とほぼ隙間なく密着している。また、導電性樹脂として導電性シリコーンゴムなどの軟質導電性樹脂を使用することでコイル１６の動き（始動時の振動など）に追従することができる。導電層１８はコイル１６の外側に設けられており、内側には設けられていない。コイル１６の内側では放電がほとんど発生しないためである。 The conductive layer 18 covers the entire outer circumference of the coil 16 from the lower end to the upper end. The conductive layer 18 is made of, for example, a conductive resin containing carbon or a conductive adhesive, and is in close contact with the conductive wire 30 of the coil 16 (see FIG. 3) with almost no gaps. Further, by using a soft conductive resin such as conductive silicone rubber as the conductive resin, it is possible to follow the movement of the coil 16 (vibration at the time of starting, etc.). The conductive layer 18 is provided on the outside of the coil 16 and not on the inside. This is because almost no discharge occurs inside the coil 16.

導電層１８によれば、コイル１６の絶縁被覆３０ｂ（図３参照）に加わる電界を均一化し、部分放電の発生を抑制することができる。これにより、誘導炉１０の高耐圧化・高寿命化を実現することができる。 According to the conductive layer 18, the electric field applied to the insulating coating 30b (see FIG. 3) of the coil 16 can be made uniform, and the occurrence of partial discharge can be suppressed. Thereby, it is possible to realize a high pressure resistance and a long service life of the induction furnace 10.

緩衝材２０はコイル１６から継鉄２２に伝わる振動を吸収および緩和する。緩衝材２０はカーボンなどを含んで導電性を有している。緩衝材２０は、導電層１８と継鉄２２の間に設けられていて導電層１８と継鉄２２とを導通する。したがって、導電層１８は緩衝材２０および継鉄２２を介して接地される。 The buffer material 20 absorbs and alleviates vibrations transmitted from the coil 16 to the yoke 22. The buffer material 20 contains carbon and the like and has conductivity. The buffer material 20 is provided between the conductive layer 18 and the yoke 22 and provides electrical continuity between the conductive layer 18 and the yoke 22. Therefore, the conductive layer 18 is grounded via the buffer material 20 and the yoke 22.

継鉄２２は、略角柱形状であって緩衝材２０の周りに複数設けられる。継鉄２２はるつぼ１４の膨張力に対してコイル１６を側方から支える機能を有する。継鉄２２は筐体２６に溶接されており導通がある。 The yokes 22 have a substantially prismatic shape and are provided around the buffer material 20 in plurality. The yoke 22 has the function of laterally supporting the coil 16 against the expansion force of the crucible 14. The yoke 22 is welded to the housing 26 and has electrical continuity.

図３は、コイル１６およびその周辺部の一部拡大断面図である。図３に示すように、コイル１６は、るつぼ１４の外周を導線３０が螺旋状に巻回して形成されている。導線３０は、導体部３０ａと、該導体部３０ａの外側を覆う絶縁被覆３０ｂとを有する。導体部３０ａの内部には冷媒路３０ｃが形成されている。導線３０は断面が角型（平角型、真四角型を含む）であって、隣接するターン同士の面が接するように密に巻回されている。したがって、導線３０の隣接するターン同士の隙間がほとんどないため導体部３０ａの占める面積割合が大きく、抵抗が小さくなり発熱が少ない。また、その分電流値を大きくすることができるため、所定出力あたりのサイズを小型化することができる。さらに、分布容量が減少しコイル１６全体の浮遊容量が小さくなるという利点がある。 FIG. 3 is a partially enlarged sectional view of the coil 16 and its surrounding area. As shown in FIG. 3, the coil 16 is formed by a conducting wire 30 spirally wound around the outer periphery of the crucible 14. The conducting wire 30 has a conductor portion 30a and an insulating coating 30b covering the outside of the conductor portion 30a. A refrigerant path 30c is formed inside the conductor portion 30a. The conducting wire 30 has a rectangular cross section (including rectangular and square shapes), and is tightly wound so that the surfaces of adjacent turns are in contact with each other. Therefore, since there is almost no gap between adjacent turns of the conducting wire 30, the area ratio occupied by the conductor portion 30a is large, the resistance is small, and there is little heat generation. Furthermore, since the current value can be increased accordingly, the size per predetermined output can be reduced. Furthermore, there is an advantage that the distributed capacitance is reduced and the stray capacitance of the entire coil 16 is reduced.

さらにまた、導線３０が角型であることにより、コイル１６の内周面および外周面がほとんど凹凸のない滑らかな曲面となる。特に、外周面に凹凸がほとんどないことにより、電界集中を抑制し、継鉄２２との間で放電が発生することを抑制できる。 Furthermore, since the conducting wire 30 is rectangular, the inner and outer peripheral surfaces of the coil 16 have smooth curved surfaces with almost no irregularities. In particular, since there are almost no irregularities on the outer circumferential surface, electric field concentration can be suppressed and generation of electric discharge between the yoke 22 and the yoke 22 can be suppressed.

図３に示すように、導電層１８はコイル１６の絶縁被覆３０ｂと密着しており、汚損防止および電界集中を抑制することができる。また、導電層１８は導電性樹脂または導電性接着剤であることから絶縁被覆と密着させることが容易であり、また鉄板と較べて軽量である。 As shown in FIG. 3, the conductive layer 18 is in close contact with the insulating coating 30b of the coil 16, and can prevent contamination and suppress electric field concentration. Further, since the conductive layer 18 is made of a conductive resin or a conductive adhesive, it is easy to adhere to the insulating coating, and it is lighter than a steel plate.

また、緩衝材２０は内周面が導電層１８に接し、外周面が継鉄２２に接している。したがって、導電層１８は緩衝材２０および継鉄２２を介して接地されており、導電層１８の専用の接地手段が不要である。ただし、導電層１８は緩衝材２０および継鉄２２とは別に接地されていてもよい。 Further, the buffer material 20 has an inner peripheral surface in contact with the conductive layer 18 and an outer peripheral surface in contact with the yoke 22. Therefore, the conductive layer 18 is grounded via the buffer material 20 and the yoke 22, and a dedicated grounding means for the conductive layer 18 is not required. However, the conductive layer 18 may be grounded separately from the buffer material 20 and the yoke 22.

図４は、誘導炉における継鉄２２の周辺で発生する電界強度の解析結果を示す図であり、（ａ）は比較例１にかかる誘導炉５００Ａにおける電界強度の解析結果を示す図であり、（ｂ）は比較例２にかかる誘導炉５００Ｂにおける電界強度の解析結果を示す図であり、（ｃ）は誘導炉１０Ａにおける電界の解析結果を示す図である。誘導炉１０Ａは上記の実施形態にかかる誘導炉１０と類似の構成である。図４における濃淡地の部分は電界強度を示し、濃淡地が濃い箇所ほど電界強度が強く、薄い箇所ほど電界強度が弱い。コイル１６に高周波・高電圧の交流を印加し、継鉄２２は接地されている条件とし、コンピュータにより解析した。 FIG. 4 is a diagram showing the analysis result of the electric field strength generated around the yoke 22 in the induction furnace, and (a) is a diagram showing the analysis result of the electric field strength in the induction furnace 500A according to Comparative Example 1, (b) is a diagram showing the analysis result of the electric field strength in the induction furnace 500B according to Comparative Example 2, and (c) is a diagram showing the analysis result of the electric field in the induction furnace 10A. The induction furnace 10A has a similar configuration to the induction furnace 10 according to the above embodiment. The shaded areas in FIG. 4 indicate the electric field strength; the darker the area, the stronger the electric field strength, and the lighter the area, the weaker the electric field strength. A high-frequency, high-voltage alternating current was applied to the coil 16, and the yoke 22 was grounded for analysis using a computer.

図４（ａ）に示すように、誘導炉５００Ａは継鉄２２とコイル１６との間に円弧状の絶縁シート３２を設けたものである。従来、継鉄２２の周方向端部２２ａは電界が集中しやすいと考えられている箇所である。 As shown in FIG. 4(a), the induction furnace 500A includes an arc-shaped insulating sheet 32 between the yoke 22 and the coil 16. Conventionally, the circumferential end portion 22a of the yoke 22 is considered to be a location where electric fields tend to concentrate.

絶縁シート３２はコイル１６の外周に沿って継鉄２２との間に設けられている。絶縁シート３２は継鉄２２よりも周方向にやや長くなっている。コイル１６は表面に防塵ガラステープが設けられている条件とした。絶縁シート３２はマイカシートの条件にした。この誘導炉５００Ａにおいては、周方向端部２２ａの箇所はコイル１６に対して絶縁シート３２によって遮られている。しかしながら解析の結果からは、絶縁シート３２の周方向端部３２ａとコイル１６との隙間部分には強い電界集中が生じており、継鉄２２の周方向端部２２ａの周辺にもやや高い電界集中が生じていることが分かる。このような強い電界が生じている箇所では放電が発生する懸念がある。 The insulating sheet 32 is provided along the outer periphery of the coil 16 and between it and the yoke 22. The insulating sheet 32 is slightly longer than the yoke 22 in the circumferential direction. The coil 16 was provided with a dustproof glass tape on its surface. The insulating sheet 32 was made to be a mica sheet. In this induction furnace 500A, the circumferential end portion 22a is blocked from the coil 16 by an insulating sheet 32. However, the analysis results show that strong electric field concentration occurs in the gap between the circumferential end 32a of the insulating sheet 32 and the coil 16, and a somewhat high electric field concentration also occurs around the circumferential end 22a of the yoke 22. It can be seen that this is occurring. There is a concern that discharge may occur in areas where such a strong electric field is generated.

図４（ｂ）に示すように、誘導炉５００Ｂはコイル１６の全外周を絶縁シート３２で覆ったものである。絶縁シート３２の材質および厚みは誘導炉５００Ａの場合と同様である。解析の結果、誘導炉５００Ｂの場合、誘導炉５００Ａと同様の２か所に電界集中が生じていることが分かる。この場合も放電が発生する可能性がある。 As shown in FIG. 4(b), the induction furnace 500B has an insulating sheet 32 covering the entire outer periphery of the coil 16. The material and thickness of the insulating sheet 32 are the same as in the case of the induction furnace 500A. As a result of the analysis, it can be seen that in the case of the induction furnace 500B, electric field concentration occurs in two places similar to the induction furnace 500A. In this case as well, discharge may occur.

図４（ｃ）に示すように、誘導炉１０Ａは導電層１８ａを有する。導電層１８ａは上記の導電層１８に対応する。ここでは、解析の都合により導電層１８ａは鉄板とし、該導電層１８ａが継鉄２２と接触することでコイル１６の全周を覆う形となっている。また、コイル１６の変形を吸収するために該コイル１６との間に隙間を設けている。さらに、比較例にかかる誘導炉５００Ｂと同じ条件とするために導電層１８ａとコイル１６との間には絶縁シート３２を設けている。解析の結果、誘導炉１０Ａでは電界集中は認められず、放電が発生する可能性は極めて低いことが分かる。また、この解析の結果から上記の誘導炉１０においても放電が発生する可能性は極めて低いと考えることができる。 As shown in FIG. 4(c), the induction furnace 10A has a conductive layer 18a. The conductive layer 18a corresponds to the conductive layer 18 described above. Here, for convenience of analysis, the conductive layer 18a is a steel plate, and the conductive layer 18a comes into contact with the yoke 22 to cover the entire circumference of the coil 16. Further, a gap is provided between the coil 16 and the coil 16 in order to absorb the deformation of the coil 16. Furthermore, an insulating sheet 32 is provided between the conductive layer 18a and the coil 16 to achieve the same conditions as the induction furnace 500B according to the comparative example. As a result of the analysis, no electric field concentration was observed in the induction furnace 10A, and it was found that the possibility of electric discharge occurring is extremely low. Further, from the results of this analysis, it can be considered that the possibility that electric discharge will occur in the induction furnace 10 described above is extremely low.

上述したように、本実施の形態にかかる誘導炉１０，１０Ａでは、コイル１６の絶縁被覆３０ｂに加わる電界を均一化させて部分放電の発生を抑制することができる。これによりコイル１６に対する印加電圧を一層上昇させ、誘導炉１０のエネルギー効率を一層上昇させることができる。本願発明者の解析によれば、誘導炉１０、１０Ａは、例えば１５ｋＶでの使用が可能である。 As described above, in the induction furnaces 10 and 10A according to the present embodiment, the electric field applied to the insulating coating 30b of the coil 16 can be made uniform to suppress the occurrence of partial discharge. Thereby, the voltage applied to the coil 16 can be further increased, and the energy efficiency of the induction furnace 10 can be further increased. According to the analysis of the present inventor, the induction furnaces 10 and 10A can be used at, for example, 15 kV.

本発明は、上記した実施形態に限定されるものではなく、本発明の主旨を逸脱しない範囲で自由に変更できることは勿論である。 It goes without saying that the present invention is not limited to the embodiments described above, and can be freely modified without departing from the spirit of the present invention.

１０，１０Ａ 誘導炉
１２ 被加熱材
１４ るつぼ
１６ コイル
１８，１８ａ 導電層
２０ 緩衝材
２２ 継鉄
２４ 下部キャスタブル
２６ 筐体
２８ アース線
３０ 導線
３０ａ 導体部
３０ｂ 絶縁被覆
３２ 絶縁シート 10,10A Induction furnace 12 Heated material 14 Crucible 16 Coils 18, 18a Conductive layer 20 Buffer material 22 Yoke 24 Lower castable 26 Housing 28 Ground wire 30 Conductor 30a Conductor portion 30b Insulating coating 32 Insulating sheet

Claims (4)

被加熱材を収納するるつぼと、
前記るつぼの外周に巻回され、絶縁被覆を有するコイルと、
前記コイルの外周面を覆う導電層と、
前記導電層を介して前記コイルを外周側から保持する継鉄と、
を備え、
前記導電層および前記継鉄は接地されており、
前記導電層は導電性樹脂または導電性接着剤であり、前記コイルの絶縁被覆と密着していることを特徴とする誘導炉。 A crucible that stores the material to be heated,
a coil wound around the outer periphery of the crucible and having an insulating coating;
a conductive layer covering the outer peripheral surface of the coil;
a yoke that holds the coil from the outer peripheral side via the conductive layer;
Equipped with
the conductive layer and the yoke are grounded;
An induction furnace characterized in that the conductive layer is a conductive resin or a conductive adhesive, and is in close contact with an insulating coating of the coil . 被加熱材を収納するるつぼと、
前記るつぼの外周に巻回され、絶縁被覆を有するコイルと、
前記コイルの外周面を覆う導電層と、
前記導電層を介して前記コイルを外周側から保持する継鉄と、
を備え、
前記導電層および前記継鉄は接地されており、
前記導電層と前記コイルとの間には絶縁シートが設けられていることを特徴とする誘導炉。 A crucible that stores the material to be heated,
a coil wound around the outer periphery of the crucible and having an insulating coating;
a conductive layer covering the outer peripheral surface of the coil;
a yoke that holds the coil from the outer peripheral side via the conductive layer;
Equipped with
the conductive layer and the yoke are grounded;
An induction furnace characterized in that an insulating sheet is provided between the conductive layer and the coil . 前記導電層と前記継鉄の間に導電性の緩衝材を備え、
前記導電層は、前記緩衝材および前記継鉄を介して接地されていることを特徴とする請求項１または２に記載の誘導炉。 A conductive buffer material is provided between the conductive layer and the yoke,
The induction furnace according to claim 1 or 2 , wherein the conductive layer is grounded via the buffer material and the yoke. 前記コイルの導線は断面が角型であることを特徴とする請求項１～３のいずれか１項に記載の誘導炉。 The induction furnace according to any one of claims 1 to 3 , wherein the conductive wire of the coil has a square cross section.
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