JP3613808B2 - Processing method of conductive metal - Google Patents

Description

【００１９】
（３）式は次の（４）式に変形でき、（４）式中の（ｍ_０ ・ａ_０ ）／ｎ_０ は定数αで置き換えることができる。従って、次の（１）式にて誘導コイルの巻回数ｍを決定することができる。
【００２０】
【数２】

【００２１】
またコイルの積層高さは、コイル１巻き当たりの導体幅ｗ_０ と巻回数ｍ_０ との積で表され、一般的に一定値βに等しいことが望ましい。

【００２２】
そして（１）式及び（２）式にて決定された巻回数ｍ，コイル１巻き当たりの導体幅ｗである誘導コイル、又はこれらに近似する誘導コイルを選択し、選択した誘導コイルに交換する。
【００２３】
【実施例】
以下本発明をその実施例を示す図面に基づいて具体的に説明する。
図１は本発明方法を実施するための加工設備の回路図である。その平面断面積が可変である容器（図示せず）の周囲にはそれぞれ、導体を巻回した誘導コイル１，１，１，１が交換可能に外嵌してあり、各誘導コイル１，１，１，１は複数のタップ２，２，…を備えるトランス３，３，３，３の２次コイル側にそれぞれ接続されている。トランス３，３，３，３の１次コイル側及び容量可変のコンデンサ４，４，４，４はそれぞれ並列接続されており、これらは更にスイッチ５，５，５，５を介して高周波電源６と並列接続されている。また誘導コイル１，１，１，１は、その巻回数及びコイル１巻き当たりの導体幅が異なる複数種類を予め準備してある。
【００２４】
このような装置において、特に製品が円形断面の場合は、使用する容器の数，製品寸法等の加工スケジュールに応じて接続する誘導コイルの数及び容器の平面断面積を変更して、導電性金属の溶解又は鋳造を行うには、変更後の容器の平面断面積ａ，及び変更後の誘導コイルの接続数ｎに基づいて、所定のインダクタンスになるように次の（１）式によって誘導コイルの巻回数ｍを決定する。
ｍ＝α・（ｎ／ａ） …（１）
但し、α：定数
【００２５】
図２は、容器の平面断面積を一定とし、接続する誘導コイルの基数の変更に応じて求めた巻回数の誘導コイルに交換した場合における高周波電源の発振特性を示すグラフであり、縦軸は高周波電源の出力電圧を、また横軸はその出力電流をそれぞれ示している。
【００２６】
図２から明らかな如く、接続する誘導コイルの基数ｎが変更されても、（１）式に基づいて求めた巻回数の誘導コイルに交換することによって、電流・電圧特性は同じ線上に重なりインダクタンスは一定であることが分かる。これによって単一の高周波電源にても複数の誘導コイルを接続することができ、従来の方法より高周波電源の数を削減することが可能となり、設備費が減少する。
【００２７】
また決定した誘導コイルの巻回数ｍに基づいて、次の（２）式によって変更後の導体の誘導コイルの１巻き当たりの長手方向の幅ｗを決定する。
ｗ＝β・（１／ｍ） …（２）
但し、β：定数
【００２８】
そして（１）式にて求めた巻回数ｍ及び（２）式にて求めた幅ｗの誘導コイル，又はそれに近似する誘導コイルを選択し、現在取り付けてある誘導コイルを、選択した誘導コイルに交換した後、スイッチ５，５，…を閉じて高周波電流を誘導コイル１，１，…に与える。
【００２９】
一方、前述した如く誘導コイルの交換を行った後であっても、交換の前後において誘導コイル１，１，…の巻回数が整数倍にならない等の理由により、高周波電源６の発振特性が適正な負荷整合線から若干外れることがある。そのような場合には、コンデンサ４，４，…の容量及びトランス３，３，…のタップ２，２，…を適宜調整する。このとき従来の方法に比べてコンデンサ及びタップの調整量は小さいため、可変幅が小さいコンデンサ及びタップ数が少ないトランスを用いることができ、設備費が更に減少する。
【００３０】
次に比較試験を行った結果について説明する。
図３及び図４は、連続鋳造設備に備えられた鋳型の正断面図及び平断面図であり、図中９は平面視が長方形である筒状の鋳型である。鋳型９には上下方向に複数のスリット１１，１１，…が開設されており、スリット１１，１１，…で分けられた鋳壁９ａ，９ａ，９ｂ，９ｂには上下方向に冷却管１０，１０，…がそれぞれ埋設してある。
【００３１】
鋳型９内にはその上方から、給湯ノズル８の下端が所定長だけ延設されており、給湯ノズル８の下端付近の鋳型９の周囲には所要巻回数及び所要幅となされた誘導コイル１が鋳型９と同心状に交換自在に取り付けてある。給湯ノズル８から鋳型９内に注入された溶湯１２の湯面上にはパウダが供給されるようになっており、パウダは溶湯１２にて熱せられて溶融パウダ１４となって溶湯１２の酸化を防止する。鋳型９内の溶湯１２は、冷却管１０，１０，…内に冷却水が通流された鋳壁９ａ，９ａ，９ｂ，９ｂにて冷却収縮し、鋳壁９ａ，９ａ，９ｂ，９ｂとの間に隙間が生じる。この隙間内に溶融パウダ１４が入込んで凝固パウダ１５になり、熱伝導性を緩和しつつ溶湯１２の凝固シェル１３の成長を促進すると共に、凝固シェル１３と鋳壁９ａ，９ａ，９ｂ，９ｂとの摩擦力を低減し、鋳片と共に下方へ引き抜かれていく。
【００３２】
また前述した鋳造に際し、図示しない高周波電源から誘導コイル１へ高周波電流を与えて生じる磁場によって、溶湯１２に鋳型の中央に向かうピンチ力を発生させて前記隙間を拡大し、溶融パウダ１４の供給量を増加させることによって鋳込み速度を向上させている。
【００３３】
このような連続鋳造設備の諸元及び鋳造条件は次の通りである。

【００３４】
まず、その外径が２０ｍｍ，巻回数が４巻である誘導コイルを取り付けて鋳型を１基運転した。この場合、コンデンサの容量が０．１３３ μＦ ，トランスの１次巻回数が３０回であり、高周波電源の出力電圧，出力電流が７．５ ｋＶ，３３．４ Ａにて誘導コイルに１５０００ ＡＴの高周波電流を流すことができ、その周波数は２０±０．０２ｋＨｚ であった。また消費電力は３１３ ｋＷであった。次に、誘導コイルを外径が５ｍｍ，巻回数が１６回のものに交換して４基の鋳型の運転を行った。このときコンデンサ及びトランスの条件を変更することなく、高周波電源の出力電圧，出力電流は１５ ｋＶ ，６６．６ Ａにて誘導コイルに１５０００ ＡＴの高周波電流を流すことができ、その周波数は２０±０．０２ｋＨｚ であった。また消費電力は１２５０ｋＷであり、鋳型１基のときの略４倍であった。
【００３５】
これに対し比較例では、その出力電圧，出力電流が７．５ ｋＶ，３３．４ Ａである高周波電源を４基準備し、各高周波電源と４基の鋳型に取り付けた誘導コイルそれぞれとを１対１となるように接続して全鋳型を運転した。このときの消費電力は１２５０ｋＷであり、従来方法の発振効率は本発明方法と同等であったが、高周波電源の配置基数が多いため、設備の建設費は本発明方法を採用した場合に比べて略２倍であった。
【００３６】
図５は誘導炉を示す模式的正断面図であり、図中２１はチャンバである。チャンバ２１の底部近傍には排気管２５及び給気管２４が接続してあり、チャンバ２１内を不活性ガスにて置換するようになっている。チャンバ２１内の略中央には金属円筒状の坩堝２９が配置されており、坩堝２９の上方には溶融材料２７を保持・投入するホッパ２６が坩堝２９と同軸状に設けられている。また坩堝２９の下方にはその上端に所要径の金属母材２２を支持する支持棒２３が昇降自在に配置してあり、金属母材２２の上端が坩堝２９中央の所定位置に達するまでこれを挿入する。
【００３７】
坩堝２９には上下方向に開設したスリットが複数形成されており、その平面断面積の寸法を変更し得るようになしてある。また坩堝２９の壁の内部にはその全周・全長にわたって空間部３０が設けられており、該空間部３０内にはチャンバ２１外から冷却水を流通させ得るようになっている。空間部３０はその幅が坩堝２９の上・下端付近では大きく、その間では小さくなしてあり、幅が小さくなった部分の坩堝２９の周囲には、所要巻回数及び所要幅となされた誘導コイル１が鋳型２９と同心状に交換自在に取り付けてある。誘導コイル１にはチャンバ２１外に設置してある高周波電源（図示せず）から高周波電流が与えられるようになており、誘導コイル１にて前記金属母材２２の上端が溶融されて形成された溶湯プール２８へ前記ホッパ２６から投入された溶融材料２７はここで溶融された後、坩堝２９の下端にて冷却凝固され下方へ引き抜かれる。
【００３８】
このような誘導炉の諸元及び鋳造条件は次の通りである。

【００３９】
まず、その断面寸法が１５ｍｍ×１５ｍｍ，巻回数が４回である誘導コイル１を取り付けて坩堝２９を１基運転した。この場合、コンデンサの容量が０．１３３ μＦ ，トランスの１次巻回数が３０回であり、高周波電源の出力電圧，出力電流が３．７５ｋＶ，１６．７ Ａにて誘導コイルに４０００ ＡＴ の高周波電流を流すことができ、その周波数は２０±０．０２ｋＨｚ であった。また消費電力は７８．３ｋＷであった。次に、誘導コイル１を断面寸法が３．７ｍｍ ×１０ｍｍ，巻回数が１６巻のものに交換して４基の坩堝の運転を行った。このときコンデンサ及びトランスの条件を変更することなく、高周波電源の出力電圧，出力電流が７．５ｋＶ ，３３．３ Ａにて誘導コイルに４０００±１０ＡＴの高周波電流を流すことができ、その周波数は２０±０．０２ｋＨｚ であった。また消費電力は３１３ ｋＷであり、坩堝１基のときの略４倍であった。
【００４０】
これに対し比較例では、その出力電圧，出力電流が３．７５ｋＶ，１６．７ Ａである高周波電源を４基準備し、各高周波電源と４基の坩堝２９に取り付けた誘導コイルそれぞれとを１対１となるように接続して全坩堝を運転した。このときの消費電力は３１３ ｋＷであり、従来方法の発振効率は本発明方法と同等であったが、高周波電源の配置基数が多いため、設備の建設費は本発明方法を採用した場合に比べて略２倍であった。
【００４１】
【発明の効果】
以上詳述した如く本発明に係る方法にあっては、容器の平面断面積の変更及び誘導コイルの接続数に応じて誘導コイルの巻回数及び１巻き当たりの導体幅を決定することによって、１基の高周波電源にて複数の誘導コイルを接続することができるため、高周波電源の基数を容器の基数より減じることができ、設備費が減少する。また決定した巻回数及び導体幅に従う誘導コイルを選択するため、インダクタンスを一定とべく行うトランス及びコンデンサの調整量が減少して、タップ数が少ないトランス，及び可変幅が小さいコンデンサを用いることができ設備費が更に減少する等、本発明は優れた効果を奏する。
【図面の簡単な説明】
【図１】本発明方法を実施するための加工設備の回路図である。
【図２】容器の平面断面積を一定とし、接続する誘導コイルの基数の変更に応じて求めた巻回数の誘導コイルに交換した場合における高周波電源の発振特性を示すグラフである。
【図３】連続鋳造設備に備えられた鋳型の正断面図である。
【図４】連続鋳造設備に備えられた鋳型の平断面図である。
【図５】誘導炉を示す模式的正断面図である。
【図６】従来方法を実施するための加工設備の一例を示す回路図である。
【符号の説明】
１ 誘導コイル
２ タップ
３ トランス
４ コンデンサ
５ スイッチ
６ 高周波電源
８ 給湯ノズル
９ 鋳型
１０ 冷却管
１２ 溶湯
１３ 凝固シェル
１４ 溶融パウダ
１５ 凝固パウダ[0001]
[Industrial application fields]
The present invention relates to a method for attaching a induction coil to a plurality of crucibles or containers such as a mold, and performing processing such as melting or casting of a conductive metal using electromagnetic induction generated in the induction coil.
[0002]
[Prior art]
For example, in Japanese Patent Application Laid-Open No. 4-13445, in a continuous casting facility provided with a plurality of molds, an induction coil is disposed concentrically around each mold, and a high frequency power source provided corresponding to each induction coil. From this, a high frequency current is applied to the induction coil, and a pinch force is generated in the molten metal supplied in the mold toward the center of the mold, thereby producing a gap between the molten metal surface and the inner wall surface of the mold for casting. Is disclosed. This increases the inflow of powder between the solidified shell and the cast wall, increases the lubricity and improves the casting speed, improves the shape of the initial solidified shell, and the oscillation mark generated by the vibration of the mold. Reduces the quality of the slab.
[0003]
On the other hand, in JP-A-2-287091, an induction coil is disposed around a plurality of metal crucibles in which cooling pipes are embedded, and the winding density of the coils is varied in the vertical direction of the crucible, respectively. By applying a high frequency current to the induction coil from a high frequency power source provided corresponding to each induction coil, and melting and mixing the conductive metal material put into the crucible by electromagnetic induction while cooling the crucible wall, A method for producing an alloy having a high purity by preventing the mixing of impurities is disclosed.
[0004]
FIG. 6 is a circuit diagram showing an example of processing equipment for implementing the above-described conventional method. In FIG. 6, an induction coil is oscillated using a parallel resonance circuit. A plurality of containers such as a mold and a crucible for charging the metal material are provided, and the plane cross-sectional area is variable. Induction coils 31, 31, 31, 31 are provided around a plurality of containers (not shown) whose plane cross-sectional areas are variable, and the induction coils 31, 31, 31, 31 are a plurality of taps. Are connected to the secondary coil side of transformers 33, 33, 33, 33 provided with 32, 32,. Further, the primary coil side of the transformers 33, 33, 33, 33 and the variable capacitance type capacitors 34, 34, 34, 34 are connected to the induction coils 31, 31, 31, 31 via the switches 35, 35, 35, 35. They are connected in parallel to the corresponding high-frequency power sources 36, 36, 36, 36. And according to the processing schedule, the number of connections between the induction coil and the power source and the planar cross-sectional area of the container are changed.
[0005]
In such an apparatus, in order to melt or cast the conductive metal, switches 35, 35,... Related to the containers to be used are connected, and high frequency currents are induced from the high frequency power sources 36, 36,. ..., the conductive metal is heated using electromagnetic induction generated by the induction coils 31, 31, ..., or a pinch force is applied to perform melting or casting.
[0006]
In order to increase / decrease the number of induction coils to be connected and change the plane cross-sectional area of the container according to the processing schedule, firstly, the transformers 33, 33,... And capacitors 34, 34,. The capacities of taps 32, 32,... And capacitors 34, 34,.
[0007]
When the planar cross-sectional area of the container and the length of the induction coils 31, 31,... Arranged in the container are increased, the inductance of the induction coils 31, 31,. The electromagnetic effect that the induction coils 31, 31, ... have on the conductive metal in the container is proportional to the magnetic flux density generated by the induction coils 31, 31, ..., but the output of the high frequency power sources 36, 36, ... is constant. In this case, since the magnetic flux density decreases as the inductance increases, electromagnetic effects such as heating and pinch force received by the conductive metal decrease, resulting in a decrease in processing speed or a decrease in quality. On the other hand, since the magnetic flux density is proportional to the voltage applied to the induction coils 31, 31,..., In order to give an equivalent electromagnetic effect to the conductive metal to the same extent before and after the change of the plane cross-sectional area of the container, The voltage applied to the induction coils 31, 31,... Is increased, that is, the operation is switched to the taps 32, 32,.
[0008]
Further, when the inductance of the induction coils 31, 31,... Increases, the resonance frequency decreases in inverse proportion to the square root of the inductance. Reducing the resonant frequency reduces the value of the magnetic shield parameter and increases the instability of the molten conductive metal with respect to the free surface shape. Therefore, in order to make the resonance frequency constant, an operation of decreasing the capacitances of the capacitors 34, 34,... In inverse proportion to the increase in inductance is performed.
[0009]
On the contrary, when reducing the planar cross-sectional area of the container, the opposite operation is performed. Then, the switches 35, 35,... Are closed and the other switches 35, 35,. Electromagnetic induction can also be performed by an oscillation method other than such a parallel oscillation circuit, but even in such a case, each change of the capacitance of the capacitor and switching of the tap is accompanied by a change in the plane cross-sectional area of the container. The operation is performed.
[0010]
[Problems to be solved by the invention]
However, in the conventional method, a high-frequency power source must be provided for each induction coil, and a transformer having a large number of taps and a variable width are provided in order to cope with a change in the planar cross-sectional area of the container. There was a problem that the equipment cost was high because a large capacitor had to be provided.
The present invention has been made in view of such circumstances, and an object of the present invention is to select an induction coil according to the number of turns and the coil width determined according to the change in the number of connections of the induction coil and the plane cross-sectional area of the container. Accordingly, an object of the present invention is to provide a method for processing a conductive metal that can reduce the installation cost by reducing the number of installed high-frequency power supplies.
[0011]
[Means for Solving the Problems]
According to a first aspect of the present invention, there is provided a method for processing a conductive metal, comprising: a plurality of containers having a variable plane cross-sectional area, fitted with induction coils that can be freely disconnected from a power source; The plane cross-sectional area and the number of induction coil connections to the power source are determined, a conductive metal is inserted into a container having an induction coil connected to the power source, and the conductive metal is introduced using electromagnetic induction by the induction coil. In the processing method, a plurality of induction coils having different numbers of turns of the induction coil and a conductor width per one turn in the axial length direction are prepared, and are determined in accordance with the planar cross-sectional area of the container and the number of induction coils connected. The number of turns is determined so as to obtain an inductance, and the conductor width is determined so as to obtain a predetermined coil height according to the number of turns, and an induction coil is selected according to the determined result.
[0012]
The conductive metal processing method according to the second invention is characterized in that, in the first invention, the winding number m is determined by the following equation (1).
m = α · (n / a) (1)
Where n: number of connected induction coils a: plane cross-sectional area of the container α: constant
The conductive metal processing method according to a third aspect of the present invention is characterized in that, in the first aspect, the conductor width w is determined by the following equation (2).
w = β · (1 / m) (2)
Where m: number of turns of induction coil β: constant
[Action]
Now, around the plurality of containers of cylindrical plane cross-sectional area is a ₀ (a plane cross-sectional area is variable), the induction coil are disposed respectively interchangeably, all induction coils parallel to one high frequency power source Yes form to be connectable, the connection number is assumed to be n _0. In addition, the induction coil has a winding number m ₀ of the induction coil so that the inductance of the induction coil and the magnetic flux density thereof are optimal, and the width per turn in the axial length direction of the induction coil of the conductor constituting the induction coil ( A conductor having a width (w ₀ ) is attached.
[0015]
In such an apparatus, even if the number of induction coils connected and the plane cross-sectional area of the container are changed according to the processing schedule, if the inductance of the entire load with respect to the high-frequency power source is constant, resonance will occur before and after the change. The frequency does not change. On the other hand, when the number of turns of the induction coil is constant, the inductance of the entire load with respect to the high-frequency power source decreases approximately inversely proportional to the number of induction coil connections, and the inductance of each induction coil is approximately proportional to the plane cross-sectional area of the container. Then increase. Therefore, the resonance frequency can be made constant by determining the number of turns of the induction coil so as to make the inductance constant according to the number of induction coils connected and the planar cross-sectional area of the container.
[0016]
On the other hand, if the number of turns to the induction coil is different, a change in magnetic flux density is caused. In order to avoid this, the conductor width is determined so that the coil height, which is the product of the conductor width and the number of turns, becomes constant according to the number of turns determined as described above. A plurality of induction coils having different numbers of turns and conductor widths are prepared, and induction coils according to the number of turns and the conductor widths determined as described above according to changes in the number of induction coils connected and the plane cross-sectional area of the container are prepared. By selecting, even if the number of induction coils connected and the planar cross-sectional area of the container are changed, the inductance and the magnetic flux density become substantially constant.
[0017]
As described above, when the number n of induction coil connections and the plane sectional area a of the container are changed according to the machining schedule, the inductance becomes constant by satisfying the following expression (3).
[0018]
[Expression 1]

[0019]
The expression (3) can be transformed into the following expression (4), and (m ₀ · a ₀ ) / n ₀ in the expression (4) can be replaced with a constant α. Therefore, the number of turns m of the induction coil can be determined by the following equation (1).
[0020]
[Expression 2]

[0021]
The coil stacking height is represented by the product of the conductor width w ₀ per coil winding and the number of turns m _0, and is generally preferably equal to a constant value β.

[0022]
Then, the induction coil having the number of turns m determined by the equations (1) and (2) and the conductor width w per coil winding, or an induction coil similar to these, is selected and replaced with the selected induction coil. .
[0023]
【Example】
Hereinafter, the present invention will be described in detail with reference to the drawings illustrating embodiments thereof.
FIG. 1 is a circuit diagram of a processing facility for carrying out the method of the present invention. Inductive coils 1, 1, 1, 1 wound with conductors are fitted around the containers (not shown) whose plane cross-sectional areas are variable, respectively, so that they can be replaced. , 1, 1 are respectively connected to the secondary coil sides of transformers 3, 3, 3, 3 having a plurality of taps 2, 2,. The primary coil side of the transformers 3, 3, 3 and 3 and the variable-capacitance capacitors 4, 4, 4 and 4 are respectively connected in parallel. And connected in parallel. The induction coils 1, 1, 1, 1 are prepared in advance in a plurality of types having different numbers of turns and different conductor widths per coil.
[0024]
In such an apparatus, particularly when the product has a circular cross section, the number of containers used, the number of induction coils to be connected and the plane cross-sectional area of the container are changed according to the processing schedule such as the product dimensions. In order to perform melting or casting of the induction coil, the following equation (1) is used to obtain a predetermined inductance based on the plane cross-sectional area a of the container after the change and the number n of induction coil connections after the change. The winding number m is determined.
m = α · (n / a) (1)
Where α: constant
FIG. 2 is a graph showing the oscillation characteristics of the high-frequency power source when the plane cross-sectional area of the container is constant and the container is replaced with an induction coil having the number of turns determined according to the change in the radix of the induction coil to be connected. The output voltage of the high frequency power source is shown, and the horizontal axis shows the output current.
[0026]
As is apparent from FIG. 2, even if the radix n of the induction coil to be connected is changed, the current / voltage characteristics overlap on the same line by replacing the induction coil with the number of turns determined based on the equation (1). Is constant. As a result, a plurality of induction coils can be connected to a single high-frequency power source, and the number of high-frequency power sources can be reduced as compared with the conventional method, thereby reducing the equipment cost.
[0027]
Further, based on the determined number of turns m of the induction coil, the width w in the longitudinal direction per turn of the conductor induction coil after the change is determined by the following equation (2).
w = β · (1 / m) (2)
However, β: constant [0028]
Then, an induction coil having the number of turns m obtained by the equation (1) and an induction coil having a width w obtained by the equation (2) or an induction coil similar thereto is selected, and the induction coil currently attached is selected as the selected induction coil. After the replacement, the switches 5, 5,... Are closed to apply a high frequency current to the induction coils 1, 1,.
[0029]
On the other hand, even after the induction coil has been replaced as described above, the oscillation characteristics of the high-frequency power source 6 are appropriate because the number of turns of the induction coils 1, 1,. May slightly deviate from the load matching line. In such a case, the capacities of the capacitors 4, 4,... And the taps 2, 2,. At this time, since the adjustment amount of the capacitor and the tap is small as compared with the conventional method, a capacitor having a small variable width and a transformer having a small number of taps can be used, and the equipment cost is further reduced.
[0030]
Next, the results of comparative tests will be described.
3 and 4 are a front sectional view and a plan sectional view of a mold provided in a continuous casting facility, and 9 in the figure is a cylindrical mold having a rectangular plan view. A plurality of slits 11, 11,... Are formed in the mold 9 in the vertical direction, and cooling pipes 10, 10 are formed in the casting walls 9 a, 9 a, 9 b, 9 b divided by the slits 11, 11,. , ... are buried.
[0031]
A lower end of the hot water supply nozzle 8 is extended from the upper side in the mold 9 by a predetermined length, and the induction coil 1 having a required number of turns and a required width is provided around the mold 9 near the lower end of the hot water supply nozzle 8. It is attached concentrically with the mold 9 so as to be exchangeable. Powder is supplied onto the surface of the molten metal 12 injected into the mold 9 from the hot water supply nozzle 8, and the powder is heated by the molten metal 12 to become molten powder 14 to oxidize the molten metal 12. To prevent. The molten metal 12 in the mold 9 is cooled and contracted by the cast walls 9a, 9a, 9b, 9b through which the cooling water is passed through the cooling pipes 10, 10,..., And the cast walls 9a, 9a, 9b, 9b. There is a gap between them. The molten powder 14 enters the gap to become the solidified powder 15, which promotes the growth of the solidified shell 13 of the molten metal 12 while relaxing the thermal conductivity, and at the same time, the solidified shell 13 and the cast walls 9 a, 9 a, 9 b, 9 b. The frictional force is reduced, and it is drawn downward together with the slab.
[0032]
In addition, during the above-described casting, a magnetic field generated by applying a high frequency current from a high frequency power source (not shown) to the induction coil 1 generates a pinch force in the molten metal 12 toward the center of the mold, thereby expanding the gap and supplying the molten powder 14. The casting speed is improved by increasing.
[0033]
The specifications and casting conditions of such a continuous casting facility are as follows.

[0034]
First, an induction coil having an outer diameter of 20 mm and a winding number of 4 was attached, and one mold was operated. In this case, the capacity of the capacitor is 0.133 μF, the number of primary turns of the transformer is 30 times, the output voltage and output current of the high frequency power supply are 7.5 kV, 33.4 A, and the induction coil is 15000 AT. A high-frequency current could flow, and the frequency was 20 ± 0.02 kHz. The power consumption was 313 kW. Next, the induction coil was replaced with one having an outer diameter of 5 mm and the number of turns of 16, and four molds were operated. At this time, without changing the conditions of the capacitor and the transformer, the output voltage and output current of the high-frequency power source are 15 kV and 66.6 A, and a high-frequency current of 15000 AT can flow through the induction coil, and the frequency is 20 ±. It was 0.02 kHz. The power consumption was 1250 kW, which was about 4 times that of the case of one mold.
[0035]
On the other hand, in the comparative example, four high-frequency power supplies having output voltages and output currents of 7.5 kV and 33.4 A are prepared, and each high-frequency power supply and each of the induction coils attached to the four molds are 1 All molds were operated with a pair of connections. The power consumption at this time is 1250 kW, and the oscillation efficiency of the conventional method is equivalent to that of the method of the present invention. However, since the number of high frequency power supply arrangements is large, the construction cost of the equipment is compared with the case of adopting the method of the present invention. It was about twice.
[0036]
FIG. 5 is a schematic front sectional view showing an induction furnace, in which 21 is a chamber. An exhaust pipe 25 and an air supply pipe 24 are connected near the bottom of the chamber 21 so that the inside of the chamber 21 is replaced with an inert gas. A metal cylindrical crucible 29 is disposed substantially in the center of the chamber 21, and a hopper 26 for holding and charging the molten material 27 is provided coaxially with the crucible 29 above the crucible 29. Below the crucible 29, a support rod 23 for supporting the metal base material 22 having a required diameter is disposed at its upper end so as to be movable up and down, and this is supported until the upper end of the metal base material 22 reaches a predetermined position in the center of the crucible 29. insert.
[0037]
The crucible 29 is formed with a plurality of slits opened in the vertical direction so that the dimension of the plane cross-sectional area can be changed. In addition, a space 30 is provided in the wall of the crucible 29 over the entire circumference and length thereof, and cooling water can be circulated from outside the chamber 21 in the space 30. The width of the space 30 is large in the vicinity of the upper and lower ends of the crucible 29, and is reduced between them. Around the crucible 29 in the reduced width portion, the induction coil 1 having the required number of turns and the required width is provided. Is mounted concentrically with the mold 29 so as to be exchangeable. The induction coil 1 is supplied with a high-frequency current from a high-frequency power source (not shown) installed outside the chamber 21, and the induction coil 1 is formed by melting the upper end of the metal base material 22. The molten material 27 introduced from the hopper 26 into the molten metal pool 28 is melted here, and then cooled and solidified at the lower end of the crucible 29 and drawn downward.
[0038]
The specifications and casting conditions of such an induction furnace are as follows.

[0039]
First, the induction coil 1 having a cross-sectional dimension of 15 mm × 15 mm and the number of turns of 4 was attached, and one crucible 29 was operated. In this case, the capacitance of the capacitor is 0.133 μF, the number of primary turns of the transformer is 30 times, the output voltage and output current of the high frequency power supply are 3.75 kV, 16.7 A, and the induction coil has a high frequency of 4000 AT. A current could be passed and the frequency was 20 ± 0.02 kHz. The power consumption was 78.3 kW. Next, the induction coil 1 was replaced with one having a cross-sectional dimension of 3.7 mm × 10 mm and the number of turns of 16, and four crucibles were operated. At this time, a high frequency current of 4000 ± 10 AT can be passed through the induction coil with the output voltage and output current of the high frequency power supply of 7.5 kV and 33.3 A without changing the conditions of the capacitor and the transformer. 20 ± 0.02 kHz. The power consumption was 313 kW, which was about 4 times that of one crucible.
[0040]
On the other hand, in the comparative example, four high-frequency power sources having output voltages and output currents of 3.75 kV and 16.7 A are prepared, and each high-frequency power source and each induction coil attached to the four crucibles 29 are each 1 All the crucibles were operated in a pair-to-one connection. The power consumption at this time is 313 kW, and the oscillation efficiency of the conventional method is equivalent to that of the method of the present invention. It was almost twice.
[0041]
【The invention's effect】
As described above in detail, in the method according to the present invention, the number of turns of the induction coil and the conductor width per turn are determined according to the change in the plane cross-sectional area of the container and the number of induction coils connected. Since a plurality of induction coils can be connected by the basic high frequency power source, the base number of the high frequency power source can be reduced from the base number of the container, and the equipment cost is reduced. In addition, since the induction coil according to the determined number of turns and the conductor width is selected, the amount of adjustment of the transformer and the capacitor for keeping the inductance constant is reduced, and a transformer with a small number of taps and a capacitor with a small variable width can be used. The present invention has excellent effects such as further reduction in equipment costs.
[Brief description of the drawings]
FIG. 1 is a circuit diagram of processing equipment for carrying out the method of the present invention.
FIG. 2 is a graph showing the oscillation characteristics of a high-frequency power source when the planar cross-sectional area of the container is constant and the induction coil is replaced with an induction coil having the number of turns determined according to a change in the number of induction coils to be connected.
FIG. 3 is a front sectional view of a mold provided in a continuous casting facility.
FIG. 4 is a plan sectional view of a mold provided in a continuous casting facility.
FIG. 5 is a schematic front sectional view showing an induction furnace.
FIG. 6 is a circuit diagram showing an example of processing equipment for carrying out a conventional method.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Induction coil 2 Tap 3 Transformer 4 Capacitor 5 Switch 6 High frequency power supply 8 Hot water supply nozzle 9 Mold 10 Cooling pipe 12 Molten metal 13 Solidified shell 14 Molten powder 15 Solidified powder

Claims (3)

A plurality of containers with variable plane cross-sectional areas are fitted with induction coils that can be disconnected from the power supply, and the cross-sectional area of the container and the number of induction coil connections to the power supply are determined according to the processing schedule. In the method of charging the conductive metal into a container having an induction coil connected to a power source, and processing the conductive metal using electromagnetic induction by the induction coil,
A plurality of induction coils having different numbers of windings of the induction coil and conductor widths per one turn in the axial length direction are prepared, and a predetermined inductance is obtained according to the planar cross-sectional area of the container and the number of induction coil connections. A conductive metal processing method comprising: determining the number of turns, determining a conductor width so as to obtain a predetermined coil height according to the number of turns, and selecting an induction coil according to the determined results. The conductive metal processing method according to claim 1, wherein the winding number m is determined by the following equation (1).
m = α · (n / a) (1)
Where n: number of connected induction coils a: plane cross-sectional area of the container α: constant The conductive metal processing method according to claim 1, wherein the conductor width w is determined by the following equation (2).
w = β · (1 / m) (2)
Where m: number of turns of induction coil β: constant

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