JPH06179956A - Method and device for coating hot-dip coated steel sheet - Google Patents

Abstract

PURPOSE:To enable a smooth and uniform coating at a high speed by arranging high frequency current conductive passages at both edge parts in the width direction of a steel sheet near gas wiping nozzles and energizing the high frequency current having the large same phase to the passages. CONSTITUTION:Gas is injected on the steel sheet S drawn up from hot dipping bath 3 from the gas wiping nozzles 1 to remove the excess molten metal stuck to the both surfaces. In a control method for the coating rate, the high frequency current conductive passages 4a paralleled to the steel sheet surfaces and mutually faced while inserting the steel sheet S are arranged at both edge part position in the width direction of the steel sheet near the gas wiping nozzle 1. To the conductive passage 4a pair, the high frequency current having the same phase in such sufficient quantity that the steel sheet S can magnetically be saturated, is energized to induce the high frequency current having the reverse phase in the steel sheet S. By this method, while preventing the vibration of the steel sheet S by generating magnetic pressure, the centering is executed. Further, the generated Lorentz force is cooperated with the gas from the gas wiping nozzles 1 to execute the wiping to the molten metal at the edge parts.

Description

【発明の詳細な説明】Detailed Description of the Invention

【０００１】[0001]

【産業上の利用分野】本発明は連続溶融亜鉛めっき等の
溶融めっきにおいて、鋼板に付着した溶融金属をワイピ
ングし、めっき鋼板の目付を行うための方法およびその
実施に好適な装置に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for wiping molten metal adhering to a steel sheet and performing a basis weight of the plated steel sheet in hot dip galvanizing and the like, and an apparatus suitable for carrying out the method.

【０００２】[0002]

【従来技術】鋼板の連続溶融めっき処理では、図１４に
示すように溶融めっき浴３中のシンクロール８に巻付搬
送される鋼板Ｓが、押えおよび板反り矯正用のピンチロ
ール９を経て上方に引き上げられた後、通常、めっき浴
面上でガスワイピングノズル１０により余剰めっき分を
絞り取られ、均一なめっき厚が得られるようにしてい
る。2. Description of the Related Art In continuous hot-dip galvanizing of steel sheets, as shown in FIG. 14, a steel sheet S wound and conveyed around a sink roll 8 in a hot-dip galvanizing bath 3 passes upward through a pinch roll 9 for pressing and straightening warp. After being pulled up, the excess plating is usually squeezed out by the gas wiping nozzle 10 on the surface of the plating bath so that a uniform plating thickness can be obtained.

【０００３】このようなめっき方法では、ガスワイピン
グノズル１０を出たガスは鋼板Ｓに衝突した後、上方お
よび下方への流れとなって溶融金属（めっき金属）を下
方に掻き落す絞り作用を行う。しかしながら、鋼板の幅
方向両端部ではガスの流れが下方向だけでなく鋼板幅方
向外側に向かうため、溶融金属が鋼板端部に向かって流
れ、この結果絞り作用が低減し、鋼板端部でめっき膜厚
が増大するという欠点（所謂、エッジオーバーコート）
があった。このようにめっき目付量が不均一であると、
美観上の問題のみならず、めっき後の合金化の不均一化
や巻取時の荷崩れの原因となる。In such a plating method, the gas discharged from the gas wiping nozzle 10 collides with the steel plate S and then flows upward and downward to perform a throttling action for scraping molten metal (plating metal) downward. . However, at both ends of the steel sheet in the width direction, the gas flows not only downward but outward in the width direction of the steel sheet, so that the molten metal flows toward the edge of the steel sheet. The drawback of increased film thickness (so-called edge overcoat)
was there. If the coating weight is uneven in this way,
This causes not only aesthetic problems but also non-uniform alloying after plating and load collapse during winding.

【０００４】従来、めっき膜厚均一化に対応するために
余剰な溶融金属を絞り取る方法に関して、以下のような
提案がなされている。 特公昭４４−７４４４号に示されるように、鋼板に高
周波磁場を印加し、鋼板に発生する渦電流に伴うローレ
ンツ力を利用して溶融金属を絞り、且つガスワイピング
を併用する方法 特開昭６１−２２７１５８号に示されるように、鋼板
に定常電流を流し、静磁場とのローレンツ力により余剰
溶融金属を下方に絞った後、ガスワイピングノズルに到
らしめる方法 特開昭６１−２０４３６３号に示されるように、鋼板
の面外方向に静磁場を発生させ、鋼板の移動により発生
する溶融金属中の誘導電流と静磁場とのローレンツ力に
より、余剰の溶融金属を下方に絞った後、ガスワイピン
グノズルに到らしめる方法 特開昭６１−２６６５６０号や特開昭６２−１０３３
３３号に示されるように、鋼板下方向に移動磁界を発生
させ余剰溶融金属を下方に絞った後、ガスワイピングノ
ズルに到らしめる方法Conventionally, the following proposals have been made regarding a method of squeezing off excess molten metal in order to make the plating film thickness uniform. As disclosed in Japanese Examined Patent Publication No. 44-7444, a method of applying a high frequency magnetic field to a steel sheet, squeezing the molten metal by using Lorentz force associated with an eddy current generated in the steel sheet, and using gas wiping together. As disclosed in Japanese Patent Laid-Open No. 61-204363, a steady current is applied to a steel sheet to squeeze the excess molten metal downward by a Lorentz force with a static magnetic field and then reach a gas wiping nozzle. As described above, a static magnetic field is generated in the out-of-plane direction of the steel sheet, and the excess current of molten metal is squeezed downward by the Lorentz force between the static current and the induced current in the molten metal generated by the movement of the steel sheet, and then gas wiping is performed. Method for reaching nozzle No. 61-266560 and 62-1033
No. 33, a method of generating a moving magnetic field in the downward direction of a steel sheet and squeezing surplus molten metal downward, and then arriving at a gas wiping nozzle.

【０００５】[0005]

【発明が解決しようとする課題】しかし、これらの方法
の最大の欠点は、特に鋼板などの強磁性体に磁場を作用
させる際、鋼板は磁場の強い方に引き付けられるために
不安定な系となり、目的とするような適正な制御を行う
ことが難しいという点にある。このような制御上の問題
を回避するためには、磁場発生装置と鋼板との間隔を広
く取る必要があり、この結果、磁場の効果が極めて限定
されてしまい、本来目的としているような効果は十分に
得られない。However, the biggest drawback of these methods is that, when a magnetic field is applied to a ferromagnetic material such as a steel sheet, the steel sheet is attracted to the strong magnetic field, resulting in an unstable system. However, it is difficult to perform proper control as intended. In order to avoid such a control problem, it is necessary to widen the gap between the magnetic field generator and the steel plate, and as a result, the effect of the magnetic field is extremely limited, and the effect originally intended is not achieved. I can't get enough.

【０００６】また、溶融金属の目付量の均一化を阻害す
る要因として、鋼板の振動があるが、上述したいずれの
提案も鋼板の制振には全く効果がない。上記の特公昭
４４−７４４４号には、コイル間を通過する鋼板は磁気
的な反発力でコイル間中心にセンタリングされるとい
う、鋼板の振動抑制効果が期待し得るような内容が示さ
れているが、上述したように単に鋼板に高周波磁場を印
加した場合には、強磁性体である鋼板に磁気的吸引力が
強く作用するため、通板する鋼板がコイル方向に吸引さ
れる等、却って不安定な状態が引き起こされ、振動の抑
制等は全く期待できない。Further, although there is vibration of the steel sheet as a factor that hinders the uniforming of the basis weight of the molten metal, none of the above-mentioned proposals has any effect on the vibration damping of the steel sheet. The above Japanese Patent Publication No. 44-7444 discloses that the steel sheet passing between the coils is centered between the coils by a magnetic repulsive force, which is expected to have a vibration suppressing effect on the steel sheet. However, as described above, when a high-frequency magnetic field is simply applied to the steel sheet, the magnetic attraction force strongly acts on the steel sheet that is a ferromagnetic material, so the steel sheet that is threaded is attracted in the coil direction. A stable state is caused and vibration suppression etc. cannot be expected at all.

【０００７】このように従来の方法では、強磁性の鋼板
が磁場により吸引され、不安定な系となるという根本的
な問題があり、このため本来目的とするような十分な作
用が期待できないという欠点があった。本発明はこのよ
うな従来の問題に鑑みなされたもので、溶融めっき鋼板
の振動を防止しつつ、ガスワイピングにより本来得られ
る平滑な仕上げ表面を維持し、高速かつ均一な目付を可
能とする溶融めっき鋼板の目付方法およびその実施に好
適な装置を提供しようとするものである。As described above, the conventional method has a fundamental problem that a ferromagnetic steel sheet is attracted by a magnetic field to form an unstable system. Therefore, it is not possible to expect a sufficient effect as originally intended. There was a flaw. The present invention has been made in view of such a conventional problem, and prevents the vibration of the hot-dip galvanized steel sheet, maintains a smooth finished surface originally obtained by gas wiping, and enables a high-speed and uniform basis weight fusion. An object of the present invention is to provide a unit weight method for a plated steel sheet and an apparatus suitable for carrying out the method.

【０００８】[0008]

【課題を解決するための手段】鋼板のような強磁性体に
単に磁場を印加し、鋼板の制振やめっき目付を行おうと
しても、鋼板に磁気吸引力が作用し、鋼板がより不安定
な状態におかれることは、上述した通りである。このよ
うな問題に対し本発明者らは、図１のＢ〜Ｈ曲線に示さ
れるように鋼板の強磁性を示す領域が非飽和域に限ら
れ、飽和域では強磁性でなくなることに着目し、鋼板に
十分な飽和域に達するような高周波磁場を印加すれば、
磁気吸引力よりも高周波電流導通路を流れる電流と鋼板
中の誘導電流間に生じる反発力の方が強くなり、上記磁
気吸引力に伴う不安定性が解消されることを見出した。
さらに、誘導電流と高周波電流導通路を流れる高周波電
流によって発生する磁場との相互作用により、鋼板およ
び溶融金属に高周波電流導通路から遠ざかる方向のロー
レンツ力が生じること、そして、このような高周波磁場
の印加をガスワイピング箇所近傍の鋼板両端部に対して
行うことにより、ガスワイプと協働した溶融金属の適切
且つ効果的な絞りが可能となることを見出した。[Means for Solving the Problems] Even if a magnetic field is simply applied to a ferromagnetic material such as a steel plate to suppress the vibration of the steel plate or to provide a coating weight, the magnetic attraction force acts on the steel plate, making the steel plate more unstable. It is as described above that it is put in such a state. With respect to such a problem, the present inventors have noticed that the region showing the ferromagnetism of the steel sheet is limited to the non-saturation region as shown by the curves B to H in FIG. , If a high frequency magnetic field is applied to the steel plate to reach a sufficient saturation range,
It has been found that the repulsive force generated between the current flowing through the high-frequency current conducting path and the induced current in the steel plate is stronger than the magnetic attraction force, and the instability associated with the magnetic attraction force is eliminated.
Furthermore, the interaction between the induced current and the magnetic field generated by the high-frequency current flowing in the high-frequency current conducting path causes a Lorentz force in a direction away from the high-frequency current conducting path in the steel sheet and the molten metal, and It has been found that by performing the application to both ends of the steel plate near the gas wiping location, it is possible to appropriately and effectively restrict the molten metal in cooperation with the gas wiping.

【０００９】本発明はこのような知見に基づきなされた
もので、その特徴とするところは、溶融めっき浴の浴面
上方において、溶融めっき浴から引き出される鋼板の両
面に付着した溶融金属にガスワイピングノズルからガス
を吹き付けてめっき目付量を制御する方法において、ガ
スワイピングノズル近傍の鋼板幅方向両端部位置に、鋼
板面に平行で且つ鋼板を挾んで対向する高周波電流導通
路を配置し、鋼板を挾んで対向した前記各対の高周波電
流導通路に、鋼板を磁気的に十分に飽和させ得るに十分
な大きさの同位相の高周波電流を通電して鋼板に逆位相
の高周波電流を誘導させ、この誘導電流と前記各対の高
周波電流導通路を流れる高周波電流との相互作用によ
り、鋼板幅方向端部の両面に働く磁気圧力を発生させて
鋼板の振動を防止しつつそのセンタリングを行うととも
に、鋼板及び溶融金属に生じる高周波電流導通路から遠
ざかる方向のローレンツ力をガスワイピングノズルから
吹き付けられるガスと協働させることにより、鋼板幅方
向端部両面の溶融金属をワイピングする溶融めっき鋼板
の目付方法である。The present invention has been made on the basis of such findings, and is characterized by gas wiping the molten metal adhered to both sides of the steel sheet drawn from the hot dip bath above the bath surface of the hot dip bath. In the method of controlling the coating weight by spraying gas from the nozzle, at both ends of the steel plate width direction in the vicinity of the gas wiping nozzle, a high-frequency current conducting path that is parallel to the steel plate surface and faces the steel plate is arranged, In each pair of the high-frequency current conducting paths that face each other across, to induce a high-frequency current of the opposite phase to the steel sheet by passing a high-frequency current of the same phase of a magnitude sufficient to saturate the steel sheet magnetically, Due to the interaction between this induced current and the high-frequency current flowing through the high-frequency current conducting path of each pair, a magnetic pressure acting on both sides of the steel sheet width direction end is generated to prevent vibration of the steel sheet. Centering, and the Lorentz force generated in the steel plate and the molten metal in the direction away from the high-frequency current conducting path is made to cooperate with the gas blown from the gas wiping nozzle to wipe the molten metal on both sides in the width direction of the steel plate. This is a unit weight method for hot dip plated steel sheets.

【００１０】また、本発明の他の特徴はこのような方法
の実施に好適な装置に関し、溶融めっき浴の浴面上方位
置に、鋼板通板部を挾んで対向して配置されたガスワイ
ピングノズルと、該ガスワイピングノズルの下方近傍位
置において、鋼板面に平行で且つ鋼板幅方向の各端部を
挾んで対向することができる高周波電流導通路と、鋼板
を挾んで対向した前記各対の高周波電流導通路に、鋼板
を磁気的に十分に飽和させ得るに十分な大きさの同位相
の高周波電流を通電することができる給電手段とを備え
た溶融めっき鋼板の目付装置である。Another feature of the present invention relates to an apparatus suitable for carrying out such a method, which is a gas wiping nozzle arranged above the bath surface of the hot dip plating bath so as to face the steel sheet passing plate portion. And a high-frequency current conducting path which is parallel to the steel plate surface and can face each other in the width direction of the steel plate at a position near the gas wiping nozzle, and high-frequency currents of the pair that face the steel plate. A hot-dip galvanized steel sheet weighting apparatus comprising: a power supply means capable of passing a high-frequency current of the same phase, which is large enough to magnetically sufficiently saturate the steel sheet, in a current conducting path.

【００１１】本発明において、高周波電流導通路は鋼板
面と平行であればよく、必ずしも板幅方向に対して平行
に設ける必要はない。したがって、高周波電流導通路を
板幅方向に対して傾きをもたせたり、或いは高周波電流
導通路を曲線状に構成することもできる。高周波電流導
通路が板幅方向に対して平行な場合、高周波電流導通路
を流れる電流に対して鋼板端部を流れる誘導電流の方向
が９０°の関係になるため、この端部での磁気圧力が弱
まる傾向があり、このような問題に対しては、上記のよ
うに高周波電流導通路を板幅方向に対して傾きをもたせ
た構成とするのが有効である。また、高周波電流導通路
は、ガスワイピングノズル近傍であればその上方または
下方（若しくはその両方）のいずれに配置してもよい
が、ガスワイピングにより平滑な仕上げ面を得るという
観点から言えば、ガスワイピングノズルの下方近傍に配
置することが好ましい。また、高周波電流導通路を鋼板
幅方向の各端部において上下方向に２対以上設けること
に何ら制約はない。In the present invention, the high-frequency current conducting path need only be parallel to the steel plate surface, and does not necessarily have to be provided parallel to the plate width direction. Therefore, the high-frequency current conducting path can be inclined with respect to the plate width direction, or the high-frequency current conducting path can be formed in a curved shape. When the high-frequency current conducting path is parallel to the strip width direction, the direction of the induced current flowing through the steel sheet end is 90 ° with respect to the current flowing through the high-frequency current conducting path. Is apt to be weakened, and to solve such a problem, it is effective to make the high-frequency current conducting path inclined with respect to the plate width direction as described above. Further, the high-frequency current conducting path may be arranged above or below (or both) as long as it is in the vicinity of the gas wiping nozzle, but from the viewpoint of obtaining a smooth finished surface by gas wiping, gas It is preferable to arrange it near the lower part of the wiping nozzle. Further, there is no limitation in providing two or more pairs of high frequency current conducting paths in the vertical direction at each end in the width direction of the steel sheet.

【００１２】[0012]

【作用】本発明法の作用を、強磁性体である鋼板の磁気
特性を示す図１（磁束密度と磁界の強さとの関係図）と
本発明の一実施例である図２及び図３に基づき説明す
る。図２は本発明の一実施状況を示す正面図、図３は同
じく側面図であり、１はガスワイピングノズル、２はノ
ズルヘッダ、３は溶融めっき浴、６は溶融金属、Ｓは被
めっき鋼板である。The operation of the method of the present invention is shown in FIG. 1 (the relationship diagram between the magnetic flux density and the strength of the magnetic field) showing the magnetic characteristics of the steel sheet which is a ferromagnetic material, and FIGS. 2 and 3 showing one embodiment of the present invention. It will be explained based on. 2 is a front view showing one embodiment of the present invention, FIG. 3 is a side view of the same, 1 is a gas wiping nozzle, 2 is a nozzle header, 3 is a hot dip bath, 6 is a hot metal, and S is a steel plate to be plated. Is.

【００１３】本発明法では、溶融めっき浴３の上方に配
置されるガスワイピングノズル１の近傍の鋼板幅方向両
端部位置に、鋼板面に平行で且つ鋼板Ｓを挾んで対向す
る高周波電流導通路４ａ，４ｂを配置する。この鋼板Ｓ
を挾んで対向した各対の高周波電流導通路４ａ，４ｂ
に、鋼板を磁気的に十分に飽和させ得るに十分な大きさ
の同位相の高周波電流を流すと、鋼板Ｓにはこれと逆位
相の電流が流れる。この鋼板Ｓを流れる電流は前記高周
波電流導通路の電流とは方向が逆となるため、磁気的な
反発作用すなわち磁気圧力が鋼板表面に作用する。In the method of the present invention, a high-frequency current conducting path which is parallel to the steel plate surface and faces the steel plate S at both ends in the steel plate width direction in the vicinity of the gas wiping nozzle 1 arranged above the hot dip bath 3 is provided. 4a and 4b are arranged. This steel plate S
A pair of high-frequency current conducting paths 4a, 4b facing each other
When a high-frequency current of the same phase that is large enough to magnetically saturate the steel sheet is applied, a current of opposite phase flows to the steel sheet S. Since the current flowing through the steel sheet S has a direction opposite to that of the current in the high-frequency current conducting path, magnetic repulsion, that is, magnetic pressure acts on the surface of the steel sheet.

【００１４】鋼板のような強磁性体では透磁率が高いた
め、単に電流が流れただけでは磁気吸引力が反発力を上
回り、不安定系となってしまう。これに対し、高周波電
流導通路１の電流を大きくしていくと、図１に示す鋼板
中の磁界の振幅が大きくなり、全体的には飽和域に鋼板
が滞留する時間が長くなり、この結果、ある磁界の振幅
以上では磁気反発力が磁気吸引力よりはるかに支配的と
なる。本発明では、このように鋼板Ｓを十分に磁気的に
飽和させ得るに十分な大きさの高周波電流を高周波電流
導通路１に通電し、必要な磁気反発力を得る。この磁気
反発力は鋼板Ｓに対してその両側から非接触のバネが作
用するのと同じであり、この磁気反発力が鋼板Ｓの振動
を抑制し、センタリングを行う。Since a ferromagnetic material such as a steel plate has a high magnetic permeability, the magnetic attraction force exceeds the repulsive force and an unstable system results if the current simply flows. On the other hand, as the current in the high-frequency current conducting path 1 is increased, the amplitude of the magnetic field in the steel sheet shown in FIG. 1 is increased, and as a whole, the steel sheet stays in the saturated region for a longer time. , Above a certain magnetic field amplitude, magnetic repulsion becomes much more dominant than magnetic attraction. In the present invention, a high-frequency current having a sufficient magnitude to sufficiently saturate the steel plate S in this manner is supplied to the high-frequency current conducting path 1 to obtain the necessary magnetic repulsion force. This magnetic repulsive force is the same as that of non-contact springs acting on both sides of the steel plate S, and this magnetic repulsive force suppresses vibration of the steel plate S and performs centering.

【００１５】さらに、鋼板Ｓの端部では鋼板および溶融
金属中の誘導電流と高周波電流導通路を流れる高周波電
流によって発生する磁場との相互作用により、図２の矢
印に示すような高周波電流導通路から遠ざかる方向のロ
ーレンツ力が鋼板および溶融金属に作用する。通常の溶
融めっき金属のガスワイピングでは、ガス流が鋼板両端
部において板幅方向外側に向かうため、鋼板の両端部で
めっき膜厚が平均より厚くなる問題（エッジオーバーコ
ート）があるが、本発明法では上記ローレンツ力が溶融
めっき液を下方に絞る作用をするとともに、ガス流と逆
方向（鋼板中心部方向）に作用するローレンツ力が鋼板
端部の溶融金属を鋼板中央部方向に押し戻す働きをし、
さらに、磁気圧力による鋼板端部の溶融金属の絞り作用
が付加されるため、鋼板両端部でのエッジオーバーコー
トの発生が防止される。すなわち、磁気圧力による鋼板
の振動防止、センタリング効果と上記ローレンツ力およ
びガスワイピング作用が協働することで、極めて均一な
めっきの目付が可能となる。また、めっき表面の平滑性
はガスワイピングにより適切に維持される。Further, at the end of the steel sheet S, the interaction between the induction current in the steel sheet and the molten metal and the magnetic field generated by the high frequency current flowing through the high frequency current conducting path causes the high frequency current conducting path as shown by the arrow in FIG. Lorentz force in the direction away from acts on the steel sheet and the molten metal. In gas wiping of ordinary hot-dip galvanized metal, since the gas flow is directed outward in the plate width direction at both ends of the steel plate, there is a problem that the plating film thickness becomes thicker than average at both ends of the steel plate (edge overcoat). In the method, the Lorentz force acts to squeeze the hot dip plating solution downward, and the Lorentz force acting in the direction opposite to the gas flow (toward the center of the steel sheet) pushes the molten metal at the edge of the steel sheet back toward the center of the steel sheet. Then
Furthermore, since the action of drawing the molten metal at the ends of the steel sheet by the magnetic pressure is added, the occurrence of edge overcoat at both ends of the steel sheet is prevented. That is, the vibration prevention of the steel sheet due to the magnetic pressure, the centering effect, and the Lorentz force and the gas wiping action cooperate with each other, whereby an extremely uniform coating weight can be obtained. Further, the smoothness of the plating surface is properly maintained by gas wiping.

【００１６】[0016]

【実施例】本発明者等は、本発明の効果を検証するため
以下のようなシュミレーション解析を行った。この解析
は、図２に示す高周波電流導通路の配置例のものについ
て、以下の解析条件に基づき、鋼板が両高周波電流導通
路からそれぞれ１５ｍｍずつ離れたセンタ位置にある場
合、鋼板が上記センタ位置から片側の高周波電流導通路
側にそれぞれ５ｍｍ、１０ｍｍずつずれた場合の３水準
について行った。 コイル断面寸法：３０×５０ｍｍ コイル電流 ：３×１０⁴Ａ 周波数 ：３０００Ｈｚ 鋼板厚さ ：２．３ｍｍ 鋼板比透磁率 ：１EXAMPLES The present inventors conducted the following simulation analysis in order to verify the effect of the present invention. This analysis is based on the following analysis conditions for the arrangement example of the high-frequency current conducting path shown in FIG. 2, and when the steel sheet is at a center position 15 mm apart from both high-frequency current conducting paths, the steel sheet is at the above-mentioned center position. Was conducted for three levels in the case of being deviated by 5 mm and 10 mm, respectively, from one side to the high frequency current conducting path side. Coil cross-sectional dimension: 30 × 50 mm Coil current: 3 × 10 ⁴ A Frequency: 3000 Hz Steel plate thickness: 2.3 mm Steel plate relative permeability: 1

【００１７】この解析モデルを図９に示す。この解析の
結果、本条件における磁界の強さの片振幅は１６０００
０Ａ／ｍであり、図１および表１に示すような代表的Ｂ
〜Ｈ曲線を持つ鋼板では、鋼板は完全に飽和域にあるこ
とが判った。図１０はこの場合における最大磁気圧力の
１サイクルの解析例であり、これによれば磁気的吸引力
が磁気圧力を上回る時間は６％以下となり、且つ磁気圧
力の最大値は磁気吸引力の５倍以上であること、このた
め鋼板が強磁性体であるにもかかわらず、磁気圧力を極
めて安定して鋼板に印加できることが判明した。This analytical model is shown in FIG. As a result of this analysis, the one-sided amplitude of the magnetic field strength under this condition is 16000.
0 A / m, which is a typical B as shown in FIG. 1 and Table 1.
It was found that for steel plates with ~ H curves, the steel plates were completely in the saturation region. FIG. 10 shows an analysis example of one cycle of the maximum magnetic pressure in this case. According to this, the time when the magnetic attraction force exceeds the magnetic pressure is 6% or less, and the maximum value of the magnetic pressure is 5 times the magnetic attraction force. It is found that the magnetic pressure can be applied to the steel sheet extremely stably even though the steel sheet is a ferromagnetic material.

【００１８】次に、鋼板面上の時間平均した磁気圧力平
均値の分布を解析した例を示す。図１１は鋼板が両電流
導通路のセンタ位置にある場合、また図１２、図１３は
鋼板が上記センタ位置よりも片側の電流導通路側にそれ
ぞれ５ｍｍ、１０ｍｍずれた場合の各磁気圧力の分布を
示している。これによれば、鋼板がセンタ位置からずれ
た場合、全体として中心へ押しやろうとする力が働くこ
とが示されている。この磁気圧力は高周波電流導通路に
鋼板が近づくにしたがって大きくなるため、鋼板のセン
タリング作用に有効に働き、振動防止に効果がある。Next, an example of analyzing the distribution of the magnetic pressure average values averaged over time on the steel plate surface will be shown. FIG. 11 shows the distribution of the magnetic pressure when the steel sheet is at the center position of both current conducting paths, and FIGS. 12 and 13 show the distribution of the magnetic pressures when the steel sheet is deviated by 5 mm and 10 mm to the current conducting path side on one side from the center position. Shows. According to this, when the steel plate deviates from the center position, a force to push it toward the center as a whole works. This magnetic pressure increases as the steel sheet approaches the high-frequency current conducting path, so that it effectively acts on the centering action of the steel sheet and is effective in preventing vibration.

【００１９】また、高周波電流導通路を流れる電流によ
って発生する磁場と鋼板中の誘導電流との相互作用で生
じるローレンツ力は、図２に示すように溶融金属を下方
に絞る作用および鋼板端部での溶融金属を鋼板中央部に
押し戻す作用を生じ、絞りとエッジオーバーコートの解
消に効果があることが確認できた。上記解析条件でのロ
ーレンツ力の最大値は亜鉛に対する重力の５５０倍であ
り、ガスワイピングと同等若しくはそれを上回る溶融金
属の絞り能力があることが明らかとなった。The Lorentz force generated by the interaction between the magnetic field generated by the current flowing through the high-frequency current conducting path and the induced current in the steel sheet causes the action of squeezing the molten metal downward and the edge of the steel sheet as shown in FIG. It was confirmed that the effect of pushing back the molten metal of No. 3 to the central part of the steel sheet was produced, and it was effective in eliminating the drawing and the edge overcoat. The maximum value of the Lorentz force under the above analysis conditions is 550 times the gravity with respect to zinc, and it has been clarified that the molten metal has a drawing ability equivalent to or greater than that of gas wiping.

【００２０】以上の検討をふまえた実施例を図２ないし
図７に示す。図２および図３は本発明の一実施例を示す
もので、溶融めっき浴３の浴面上方位置に１対のワイピ
ングノズル１が鋼板通板部を挾んで対向して配置され、
このワイピングノズル１の下方近傍の鋼板幅方向両端部
位置に、鋼板面に平行で且つ鋼板Ｓを挾んで対向した高
周波電流導通路４ａ，４ｂを配置してある。この実施例
では、高周波電流導通路４ａ，４ｂを鋼板幅方向の各端
部において上下方向に２対ずつ配置してある。これら各
対の高周波電流導通路４ａ，４ｂには、給電ライン７か
ら同位相の高周波電流を並列に分配、給電できる構成と
してある。また、各対の高周波電流導通路４ａ，４ｂ
は、鋼板の板幅変更に対応するため移動手段５により鋼
板幅方向移動可能に構成してある。An embodiment based on the above examination is shown in FIGS. 2 to 7. 2 and 3 show one embodiment of the present invention, in which a pair of wiping nozzles 1 are arranged above the bath surface of the hot dip plating bath 3 so as to face each other across the steel plate passing plate portion.
High-frequency current conducting paths 4a and 4b that are parallel to the steel plate surface and face each other across the steel plate S are disposed at both ends in the steel plate width direction near the lower part of the wiping nozzle 1. In this embodiment, two pairs of high-frequency current conducting paths 4a and 4b are arranged in the vertical direction at each end in the width direction of the steel sheet. A high-frequency current of the same phase can be distributed and fed in parallel from the power feed line 7 to the high-frequency current conducting paths 4a and 4b of each pair. In addition, each pair of high frequency current conducting paths 4a, 4b
Is configured to be movable in the width direction of the steel plate by the moving means 5 in order to correspond to the change of the plate width of the steel plate.

【００２１】また、図４および図５は本発明の他の実施
例を示すもので、各対の高周波電流導通路４ａ，４ｂ
に、給電ライン７から直列に高周波電流を給電できる構
成としたものである。なお、その他の構成は図２および
図３に示す実施例と同様であるので、同一の符号を付
し、その説明は省略する。4 and 5 show another embodiment of the present invention, in which each pair of high-frequency current conducting paths 4a, 4b is provided.
In addition, the high frequency current can be fed in series from the feeding line 7. Since the other structures are similar to those of the embodiment shown in FIGS. 2 and 3, the same reference numerals are given and the description thereof is omitted.

【００２２】以上のような実施例の装置構成において、
鋼板Ｓを挾んで対向した各対の高周波電流導通路４ａ，
４ｂに、鋼板Ｓを十分に磁気的に飽和させ得るに十分な
大きさの同位相の高周波電流を流すと、鋼板Ｓにはこれ
と逆位相の電流が流れる。この鋼板Ｓを流れる誘導電流
は前記高周波電流導通路４ａ，４ｂを流れる電流とは方
向が逆となるため、磁気的な反発力（磁気圧力）が鋼板
Ｓの表面に作用し、この磁気反発力が鋼板Ｓの振動を抑
制し、センタリングを行う。In the device configuration of the above embodiment,
Each pair of high-frequency current conducting paths 4a facing each other across the steel plate S,
When a high-frequency current of the same phase that is large enough to sufficiently magnetically saturate the steel plate S is passed through 4b, a current of opposite phase flows through the steel plate S. Since the induced current flowing through the steel plate S has a direction opposite to that of the current flowing through the high frequency current conducting paths 4a and 4b, a magnetic repulsive force (magnetic pressure) acts on the surface of the steel plate S, and the magnetic repulsive force is generated. Suppresses the vibration of the steel plate S and performs centering.

【００２３】さらに、鋼板Ｓの端部では、高周波電流導
通路４ａ，４ｂを流れる高周波電流によって発生する磁
場と鋼板Ｓおよび溶融金属６中の誘導電流との相互作用
により、図２の矢印に示すような高周波電流導通路４
ａ，４ｂから遠ざかる方向のローレンツ力が、鋼板Ｓお
よび溶融金属６に作用する。そして、このローレンツ力
が溶融金属６を下方に絞る作用および鋼板端部での溶融
金属６を鋼板中央部に押し戻す作用をし、さらに、磁気
圧力による鋼板端部の溶融金属の絞り作用が付加される
ため、鋼板両端部でのエッジオーバーコートの発生が防
止される。Further, at the end of the steel sheet S, the interaction between the magnetic field generated by the high frequency current flowing through the high frequency current conducting paths 4a and 4b and the induced current in the steel sheet S and the molten metal 6 indicates an arrow in FIG. High frequency current conduction path 4
The Lorentz force in the direction away from a and 4b acts on the steel plate S and the molten metal 6. Then, this Lorentz force acts to squeeze the molten metal 6 downward and push back the molten metal 6 at the steel plate end portion to the central portion of the steel plate, and further the action of drawing the molten metal at the steel plate end portion by magnetic pressure is added. Therefore, the occurrence of the edge overcoat at both ends of the steel sheet is prevented.

【００２４】図６は本発明の他の実施例を示すもので、
１対の高周波電流導通路４ａ，４ｂ（鋼板裏面側の４ｂ
は図示せず）を鋼板幅方向に対して傾けて配置した例で
ある。高周波電流導通路４ａ，４ｂには、図２および図
３の実施例と同様、給電ラインから同位相の高周波電流
を並列に分配、給電できる構成としてある。図２ないし
図５に示すように高周波電流導通路４ａ，４ｂを鋼板幅
方向と平行に配置すると、鋼板端部を流れる誘導電流と
高周波電流導通路を流れる高周波電流とが９０°の関係
となるため、上述した磁気圧力の作用が弱まる。これに
対し、図６の実施例のように高周波電流導通路４ａ，４
ｂを鋼板幅方向に対して傾けることにより、上述したよ
うな磁気圧力の作用の減少を抑えることができる。FIG. 6 shows another embodiment of the present invention.
A pair of high frequency current conducting paths 4a, 4b (4b on the back side of the steel plate)
Is an example in which (not shown) is inclined with respect to the steel plate width direction. Similar to the embodiments of FIGS. 2 and 3, high-frequency currents of the same phase can be distributed and fed in parallel to the high-frequency current conducting paths 4a and 4b from the power feed line. When the high-frequency current conducting paths 4a and 4b are arranged parallel to the steel sheet width direction as shown in FIGS. 2 to 5, the induction current flowing through the steel sheet ends and the high-frequency current flowing through the high-frequency current conducting path have a relationship of 90 °. Therefore, the action of the magnetic pressure described above weakens. On the other hand, as in the embodiment of FIG. 6, high frequency current conducting paths 4a, 4
By tilting b with respect to the width direction of the steel plate, it is possible to suppress the above-described decrease in the action of magnetic pressure.

【００２５】また、本発明において高周波電流導通路の
形状および給電方式に特別な限定はなく、また、鋼板の
各端部に対して異なる形状の高周波電流導通路および給
電方式を適用してもよい。図７は、その一例を示すもの
で、鋼板の各端部に対して異なる形状の高周波電流導通
路４ａ，４ｂ（鋼板裏面側の４ｂは図示せず）を適用し
た実施例を示している。この実施例では、各１対の高周
波電流導通路４ａ，４ｂに、給電ライン７から直列に高
周波電流を給電できる構成としてある。なお、以上の図
６、図７の実施例における他の構成は図２および図３に
示す実施例と同様であるので、同一の符号を付し、その
説明は省略する。In the present invention, the shape of the high-frequency current conducting path and the power feeding method are not particularly limited, and different shapes of the high-frequency current conducting path and the power feeding method may be applied to each end of the steel sheet. . FIG. 7 shows an example thereof, and shows an embodiment in which high-frequency current conducting paths 4a and 4b having different shapes are applied to the respective ends of the steel sheet (4b on the back side of the steel sheet is not shown). In this embodiment, a high-frequency current can be fed in series from the feeding line 7 to each pair of high-frequency current conducting paths 4a and 4b. Since the other configurations in the embodiments of FIGS. 6 and 7 are similar to those of the embodiments shown in FIGS. 2 and 3, the same reference numerals are given and the description thereof will be omitted.

【００２６】図１４に示すような従来のめっき設備にお
いて、従来のガスワイピングノズル１０に代えて図４お
よび図５に相当する装置と図６に相当する装置をめっき
浴面上４００ｍｍの位置に設置し、板厚２．３ｍｍ、板
幅１３００ｍｍの鋼板を被めっき材とする溶融亜鉛めっ
き鋼板の目付を実施した。この試験の条件は以下の通り
である。 ・高周波電流導通路への給電条件 高周波電流：２００００Ａ 周波数：３０００Ｈｚ ・ガスワイピングヘッダ圧力：４００００Ｐａ ・ラインスピード：１５０ｍ／ｍｉｎ ・高周波電流導通路と鋼板との間隔：１５ｍｍ（設定
値）In the conventional plating equipment as shown in FIG. 14, the conventional gas wiping nozzle 10 is replaced by a device corresponding to FIGS. 4 and 5 and a device corresponding to FIG. 6 at a position 400 mm above the plating bath surface. Then, the weight of a galvanized steel sheet having a steel sheet having a sheet thickness of 2.3 mm and a sheet width of 1300 mm as a material to be plated was performed. The conditions of this test are as follows.・ Power supply condition to high frequency current conducting path High frequency current: 20000A Frequency: 3000Hz ・ Gas wiping header pressure: 40000Pa ・ Line speed: 150m / min ・ Gap between high frequency current conducting path and steel plate: 15mm (set value)

【００２７】また、比較のため上記と同じガスワイピン
グヘッダ圧力およびラインスピードで通常（従来法）の
ガスワイピングによる目付も実施（図６の装置におい
て、高周波電流導通路に通電しないで行った試験）し
た。これら各試験例で得られためっき膜厚の板幅方向分
布を図８に示す。図８では、図４および図５の装置によ
る本発明例を△印、図６の装置による本発明例を×印、
通常のガスワイピングの例を○印で示す。図８によれ
ば、○印の従来法によるめっき鋼板では著しいエッジオ
ーバーコートが生じているのに対し、△印、×印の本発
明法によるめっき鋼板では、板幅方向のめっき膜厚が極
めて均一に制御できることが判る。For comparison, a basis weight by normal (conventional method) gas wiping was also performed at the same gas wiping header pressure and line speed as described above (test conducted in the apparatus of FIG. 6 without energizing the high frequency current conducting path). did. FIG. 8 shows the distribution in the plate width direction of the plating film thickness obtained in each of these test examples. In FIG. 8, the example of the present invention by the apparatus of FIGS. 4 and 5 is marked with Δ, the example of the present invention by the apparatus of FIG. 6 is marked with X,
An example of normal gas wiping is indicated by a circle. According to FIG. 8, a marked edge overcoat is generated in the plated steel sheet according to the conventional method marked with ◯, whereas in the plated steel sheet according to the method of the present invention marked with Δ and ×, the plating film thickness in the plate width direction is extremely high. It turns out that it can be controlled uniformly.

【００２８】[0028]

【表１】 [Table 1]

【００２９】[0029]

【発明の効果】以上述べた本発明によれば、従来連続溶
融めっきの高速化でネックとなっていたガスワイピング
ノズル回りの問題を解消し、板幅方向で均一なめっき膜
厚のめっき鋼板を得ることができる。According to the present invention described above, the problems around the gas wiping nozzle, which has been a bottleneck in the conventional high-speed continuous hot-dip galvanizing, are solved, and a plated steel sheet having a uniform plating film thickness in the plate width direction is obtained. Obtainable.

【図面の簡単な説明】[Brief description of drawings]

【図１】鋼板の磁束密度と磁界の強さとの関係図[Fig. 1] Relationship diagram between magnetic flux density of steel sheet and magnetic field strength

【図２】本発明の一実施例を示す正面図FIG. 2 is a front view showing an embodiment of the present invention.

【図３】図２に示す実施例の側面図FIG. 3 is a side view of the embodiment shown in FIG.

【図４】本発明の他の実施例を示す正面図FIG. 4 is a front view showing another embodiment of the present invention.

【図５】図４に示す実施例の側面図5 is a side view of the embodiment shown in FIG.

【図６】本発明の他の実施例を示す正面図FIG. 6 is a front view showing another embodiment of the present invention.

【図７】本発明の他の実施例を示す正面図FIG. 7 is a front view showing another embodiment of the present invention.

【図８】本発明法の実施例および比較例において目付さ
れためっき鋼板の板幅方向でのめっき膜厚分布を示すグ
ラフFIG. 8 is a graph showing the distribution of plating film thickness in the plate width direction of the plated steel sheets found in Examples and Comparative Examples of the method of the present invention.

【図９】高周波電流導通路によって鋼板に及ぼされる磁
気圧力を算定するためのシュミレーションにおける解析
モデルを示す説明図FIG. 9 is an explanatory diagram showing an analytical model in a simulation for calculating a magnetic pressure exerted on a steel sheet by a high frequency current conducting path.

【図１０】図９の解析において、最大磁気圧力の１サイ
クルの解析例を示すグラフ10 is a graph showing an example of analysis of one cycle of maximum magnetic pressure in the analysis of FIG.

【図１１】図９の解析において、鋼板がセンタ位置にあ
る場合の磁気圧力の分布を示すグラフ11 is a graph showing the distribution of magnetic pressure when the steel sheet is at the center position in the analysis of FIG. 9.

【図１２】図９の解析において、鋼板がセンタ位置より
５ｍｍずれた場合の磁気圧力の分布を示すグラフFIG. 12 is a graph showing the distribution of magnetic pressure when the steel plate is displaced from the center position by 5 mm in the analysis of FIG.

【図１３】図９の解析において、鋼板がセンタ位置より
１０ｍｍずれた場合の磁気圧力の分布を示すグラフFIG. 13 is a graph showing the distribution of magnetic pressure when the steel sheet is displaced 10 mm from the center position in the analysis of FIG. 9.

【図１４】従来の溶融めっきおよび目付方法を示す説明
図FIG. 14 is an explanatory diagram showing a conventional hot dip plating and basis weight method.

【符号の説明】[Explanation of symbols]

１…ガスワイピングノズル、２…ノズルヘッダ、３…溶
融めっき浴、４ａ、４ｂ…高周波電流導通路、５…移動
手段、６…溶融金属、７…給電ライン、Ｓ…鋼板DESCRIPTION OF SYMBOLS 1 ... Gas wiping nozzle, 2 ... Nozzle header, 3 ... Molten plating bath, 4a, 4b ... High frequency current conduction path, 5 ... Moving means, 6 ... Molten metal, 7 ... Power supply line, S ... Steel plate

───────────────────────────────────────────────────── フロントページの続き (72)発明者 大久保 豊 東京都千代田区丸の内一丁目１番２号 日 本鋼管株式会社内 (72)発明者 矢田 明 東京都千代田区丸の内一丁目１番２号 日 本鋼管株式会社内 (72)発明者 杉山 峻一 東京都千代田区丸の内一丁目１番２号 日 本鋼管株式会社内 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Yutaka Okubo, 1-2, Marunouchi, Chiyoda-ku, Tokyo Japan Steel Pipe Co., Ltd. (72) Akira Yada, 1-2, Marunouchi, Chiyoda-ku, Tokyo Date Inside the Steel Pipe Co., Ltd. (72) Inventor Shuichi Sugiyama 1-2-1 Marunouchi, Chiyoda-ku, Tokyo Inside Nihon Steel Pipe Co., Ltd.

Claims (2)

【特許請求の範囲】[Claims] 【請求項１】 溶融めっき浴の浴面上方において、溶融
めっき浴から引き出される鋼板の両面に付着した溶融金
属にガスワイピングノズルからガスを吹き付けてめっき
目付量を制御する方法において、ガスワイピングノズル
近傍の鋼板幅方向両端部位置に、鋼板面に平行で且つ鋼
板を挾んで対向する高周波電流導通路を配置し、鋼板を
挾んで対向した前記各対の高周波電流導通路に、鋼板を
磁気的に十分に飽和させ得るに十分な大きさの同位相の
高周波電流を通電して鋼板に逆位相の高周波電流を誘導
させ、この誘導電流と前記各対の高周波電流導通路を流
れる高周波電流との相互作用により、鋼板幅方向端部の
両面に働く磁気圧力を発生させて鋼板の振動を防止しつ
つそのセンタリングを行うとともに、鋼板及び溶融金属
に生じる高周波電流導通路から遠ざかる方向のローレン
ツ力をガスワイピングノズルから吹き付けられるガスと
協働させることにより、鋼板幅方向端部両面の溶融金属
をワイピングすることを特徴とする溶融めっき鋼板の目
付方法。1. A method for controlling a coating weight of a molten metal adhered to both sides of a steel plate drawn from the hot dip bath by a gas wiping nozzle to control the coating weight of the molten metal above the bath surface of the hot dip bath. At both ends of the steel plate in the width direction of the steel plate, high-frequency current conducting paths that are parallel to the steel plate surface and face each other by sandwiching the steel plate are arranged, and the steel plate is magnetically attached to each pair of high-frequency current conducting paths that sandwich the steel plate and face each other. A high-frequency current of the same phase that is large enough to be sufficiently saturated is passed to induce a high-frequency current of opposite phase in the steel sheet, and the induced current and the high-frequency current flowing through the high-frequency current conducting path of each pair are mutually By the action, centering is performed while generating a magnetic pressure that works on both sides of the widthwise end of the steel sheet to prevent vibration of the steel sheet, and high-frequency current generated in the steel sheet and molten metal. A basis weight method for a hot dip plated steel sheet, wherein the Lorentz force in the direction away from the conduction path is made to cooperate with the gas blown from the gas wiping nozzle to wipe the molten metal on both end portions of the steel sheet width direction. 【請求項２】 溶融めっき浴の浴面上方位置に、鋼板通
板部を挾んで対向して配置されたガスワイピングノズル
と、該ガスワイピングノズルの近傍位置において、鋼板
面に平行で且つ鋼板幅方向の各端部を挾んで対向するこ
とができる高周波電流導通路と、鋼板を挾んで対向した
前記各対の高周波電流導通路に、鋼板を磁気的に十分に
飽和させ得るに十分な大きさの同位相の高周波電流を通
電することができる給電手段とを備えた溶融めっき鋼板
の目付装置。2. A gas wiping nozzle, which is disposed above the bath surface of the hot dip plating bath so as to face the steel sheet passing plate portion, and in the vicinity of the gas wiping nozzle, the gas wiping nozzle is parallel to the steel sheet surface and the steel sheet width. A high-frequency current conducting path that can face each other by sandwiching each end of the direction, and a high-frequency current conducting path of each pair that sandwiches and faces the steel sheet, and has a size large enough to magnetically saturate the steel sheet. Of a hot-dip galvanized steel sheet, which is provided with a power feeding means capable of passing high-frequency currents of the same phase.