JP3822709B2

JP3822709B2 - Steel surface treatment equipment

Info

Publication number: JP3822709B2
Application number: JP12832997A
Authority: JP
Inventors: 鋼治安達; 治久末; 孝大木
Original assignee: Nippon Steel Corp
Current assignee: Nippon Steel Corp
Priority date: 1997-05-19
Filing date: 1997-05-19
Publication date: 2006-09-20
Anticipated expiration: 2017-05-19
Also published as: JPH10317190A

Description

【０００１】
【産業上の利用分野】
本発明は、コイル状の鋼材を巻き戻しながら連続通材させてリン酸塩皮膜を形成させる装置に関するものである。
【０００２】
【従来の技術】
従来、鋼材へのリン酸塩処理は、部品加工用の潤滑皮膜下地処理、防錆処理、および塗装下地処理として広く利用されている。リン酸塩処理は一般的に浸漬法、スプレー法により実施される。
そこで、鋼材をリン酸亜鉛処理液に浸漬すると、以下の反応が起こる。
（アノード反応）Ｆｅ→Ｆｅ²⁺＋２ｅ^-
（カソード反応）２Ｈ⁺＋２ｅ^-→Ｈ₂
ここでアノード反応は、リン酸による鋼材面の溶解腐食反応であり、鋼材面に電子を与えるとともに鋼材表面を活性化して析出するリン酸塩の結晶と鋼材表面の密着性が確保される。また、鋼材内に与えられた電子により起こるカソード反応は溶液中に分離して浮遊していた水素イオンを水素分子へと変換する反応である。処理液の平均的なｐＨは２前後であるがカソード反応が起きた鋼材面近くではｐＨが４前後まで上昇し、リン酸亜鉛結晶（Ｚｎ₃（ＰＯ₄）₂）の析出条件を満足し、鋼材表面にリン酸亜鉛皮膜が形成される。
（３Ｚｎ（Ｈ₂ＰＯ₄）₂→Ｚｎ₃（ＰＯ₄）₂＋Ｈ₃ＰＯ₄
【０００３】
このリン酸亜鉛皮膜を下地処理として表面にステアリン酸塩等の金属石鹸からなる潤滑剤の皮膜を形成させることにより、冷間鍛造のごとく面圧が３０００（ＭＰａ）、摩擦面温度４００℃、表面積の拡大率が１００倍にも達する過酷な条件下においても鋼材と金型間の摩擦力を下げて金型の摩耗や焼き付きを防止できる。
しかしながら、このリン酸亜鉛皮膜の形成反応は電気化学反応とｐＨ変動に伴う平衡反応および結晶析出反応が互いに関連作用する複合的な反応であるため液の温度、濃度や成分変動により皮膜量が十分得られなかったり、鋼材との密着性が十分でないと上記冷間鍛造加工で焼き付き等の不具合を発生する要因となる。
【０００４】
また、皮膜付着状態を鋼材表面全体で均一に処理するために必要な時間は、平板を処理槽内に浸漬するような系、すなわち処理液が鋼材表面に対して十分置換可能な場合でも２０秒から２分程度、コイル状に巻き取られた鋼材を処理槽内に浸漬するような系、すなわちコイルの内部に滞留した処理液の置換が十分に起きない系では３分から８分という長い時間を要し生産性向上の点で問題があった。そこでリン酸塩処理の促進技術の一つとして電気的促進法が考案されている。リン酸塩処理の電気的促進技術は英国特許１６３００号（１９０９年）で直流定電流法が開示されて以来、交流通電法（例えば特公昭４９−４６２２０号公報）や、パルス電流印加法（例えば特開昭５９−１９７５９６号公報，特開平６−３２２５９２号公報）等の改良が重ねられている。
【０００５】
【発明が解決しようとする課題】
リン酸塩処理の電気的促進方法は、皮膜付着量の確保と鋼材表面との密着性を両立させることができないという問題があり実用化には至っていない。
リン酸塩溶液中で陰極電極を対面に浸漬すると鋼材表面が陽極電解されアノード反応が選択的に促進される。しかし、このときカソード反応によるｐＨ変動がほとんど起きないためリン酸塩皮膜生成量が確保できないばかりか過剰溶出したＦｅイオンがＺｎイオンと置換したリン酸亜鉛鉄（Ｚｎ₂Ｆｅ（ＰＯ₄）₂）を主成分とした皮膜が析出してしまい所期の目的を達し得ない。
【０００６】
同様にリン酸塩溶液中で陽極電極を対面に浸漬すると鋼材表面が陰極電解され、カソード反応を促進する。この結果ｐＨ変動が十分に起きるため供給電流に応じてリン酸塩皮膜生成の析出を増大させることができるが、アノード反応がないため鋼材とリン酸塩皮膜の密着性が悪く、部品加工時に剥離してしまい金型との焼付けを起こしてしまう等の問題があった。
この問題を解決する方法として鋼材に付与する電流をパルス電流や正逆反転サイクル電流とする方法（例えば特開昭５９−１９７５９６号公報）によりアノード反応とカソード反応の各々の促進する時間帯を繰り返し実施することでリン酸塩皮膜生成の析出増大を狙ったものであるが、パルス電流で陰極電解する場合では電流休止期間中に若干のアノード反応が期待できるものの直流電流と根本的には変わらない。また、正逆反転サイクル電流とした場合は、陽極電解中に処理を完了した部位の皮膜は、一旦析出した皮膜と鋼材の界面にあるＦｅが陽極電解中のアノード反応により局所的に侵食されてしまい鋼材との密着性が著しく阻害されてしまうという問題があり、所期の目的を達しえなかった。
【０００７】
また、鋼材に電流を印加する方法として線材、棒鋼、鋼板、パイプ等のコイル状に巻き取られた鋼材を巻き戻しながら通材させつつ電気的促進方を適用する場合、図４に示すごとくリン酸塩処理槽３３の入側と出側に配置した抑えローラー３２により鋼材１はリン酸塩処理液３４中に浸漬される。ここで、通電ローラー３１あるいは通電ブラシなどにより鋼材に直接接触させて、リン酸塩溶液３４中に通材方向に沿って鋼材と対面するよう配置された電極２１との間にある電源装置８により鋼材１に電流を印加する直流通電方式が採用されている。しかしこの方法では、不可避的に鋼材の凹凸、曲がり等に表面欠陥や、通電ローラーやブラシ表面の摩耗等により鋼材への電気供給時の放電が発生し孔触されたり、鋼材表面に疵が発生してしまうという問題があった。
本発明の目的は、極短時間で密着制に優れた鋼材のリン酸塩皮膜生成を可能とする鋼材の表面処理装置を提供することにある。
【０００８】
【課題を解決するための手段】
本発明の要旨は、次のとおりである。
（１）リン酸塩処理液中に鋼材を連続的に通材させながら電流を印加して鋼材表面にリン酸塩皮膜を形成させる鋼材の表面処理装置において、リン酸塩処理槽内に鋼材の経路に沿って隣り合った陰極電極と陽極電極との一対以上を各陰極電極が通材方向の上流側になるように配置し、（陰極電極の通材方向長さ／陽極電極の通材方向長さ）の比が０．２〜０．３であり、各電極は通過する鋼材に接触しない位置に配置せしめ、各対内の陰極電極と陽極電極とは直流定電流またはパルス電流を供給する単一の電源装置を介して電気的に接続して、電極と鋼材を直接接触させることなく、かつ、各対間で個別に電流印加を可能に構成したことを特徴とする鋼材の表面処理装置にある。
【０００９】
本発明はリン酸塩処理液中で鋼材の通材方向の上流側に陰極電極を、下流側に陽極電極を配置して連続的に鋼材を通材処理するのでリン酸塩処理におけるアノード反応を陰極電極による陽極電解帯で行った後、カソード反応を陽極電極による陰極電解帯で実施できるので、短時間で密着性の良い皮膜を生成できる。
また、本発明は直流定電流を印加した場合には最も効率良く電気を供給できるので、処理時間が短くなることや、電極の表面積を最小限にして設計できる等の点で優れている。また、パルス電流にした場合は電流休止期間があるため直流電流に比べると供給できる電気量は少なくなるが、鋼材表面に生成するリン酸塩皮膜の結晶が緻密になり鋼材との密着性が向上する。すなわちパルス電流では通電時の電流密度（ｉｐ）と１週期の間に電流が流れる割合（θ）の積であるパルス平均電流密度（ｉｐ×θ）が直流定電流の電流密度と同等であり、またパルス電流の電流休止期間中に鋼材表面近傍のリン酸塩処理液が置換され、再度電流が流れる際に新たな皮膜結晶析出の起点が発生し、結晶粒が緻密で微細化されるためと考えられる。
また、本発明はリン酸塩処理液中に経路に沿って浸漬配置した隣り合った電極間に電源装置を介して連接することにより鋼材と電極を直接接触させることなく鋼材に電流を印加できるので、鋼材表面の孔触や疵の発生が防止できる。また、単一の電源装置のみで陽極電解帯と陰極電解帯とをリン酸塩処理槽内に効率よく形成できる。
【００１０】
【発明の実施の形態】
次に本発明の実施の形態について説明する。
本発明の適用となる鋼材とは熱間圧延材や焼きなまし処理材はもとより、表面に亜鉛メッキ処理した鋼材、その他、原理的にリン酸塩処理が可能な全ての鋼材を対象として実施可能である。
また、本発明でいうリン酸塩とは、リン酸亜鉛、リン酸ニッケル、リン酸カルシウム、リン酸鉄の一種または２種以上を含有してなるものである。
また、本発明により鋼材に印加される電流は直流定電流あるいはパルス電流であるが、直流定電流は電流密度が５０〜２０００００Ａ／ｍ² 、の範囲であることが望ましい。電流密度がこの範囲よりも小さい場合は電流印加による促進効果がほとんど期待できなく、電流密度がこの範囲を超えると処理液の物質移動が皮膜生成速度を律速するため電流値を増やしても促進効果には影響しなくなるためである。
【００１１】
本発明について更に詳しく図示の例により説明する。図１は本発明による電流印加式のリン酸塩処理装置例の側面図である。リン酸塩処理槽３３には鋼材通材方向の上流側で陽極電解を、下流側で陰極電解を行うよう電極２１が電源装置８を介して電気的に接続されている。鋼材１は図の左方より移動し抑えローラー３２によりリン酸塩処理槽３３に導かれリン酸塩処理液３４中に浸漬される。鋼材は電源装置８の陰極側に接続した電極２１により陽極電解されアノード反応が急激に起き鋼材表面は活性化される。その後鋼材は電源装置８の陽極側に接続した電極２２により陰極電解されカソード反応が起き鋼材近傍の処理液のｐＨが上昇し極短時間で皮膜結晶が析出する。この結果、皮膜付着量の確保と鋼材表面との密着性を両立させたリン酸塩皮膜が得られる。
【００１２】
ここで陽極電解帯と陰極電解帯の総電流値は等しいため両帯の長さが等しい場合は鋼材表面の電流密度が等しく、電解帯長さが異なる場合は電解帯長さに反比例して電流密度は小さくなる。よって、陽極電解帯と陰極電解帯の長さが極端に違うと各電解反応を効率良く行うことができない。また、陰極電解帯の方がリン酸塩結晶析出のための時間を要することから、陽極電解帯と陰極電解帯との長さの比は０．２〜０．３：１．０の範囲が好ましい。
また電極の材質は、炭素電極により良好な結果が得られたが、金属であれば、白金、チタン、イリジウム等のいわゆる貴なる金属やその酸化物からなるものとすることで、電解反応時に電極がリン酸塩液中へ溶出することを防ぐことが可能である。
【００１３】
図２は本発明による電流印加式のリン酸塩処理装置の他の例の側面図である。リン酸塩処理槽３３内に陽極電解帯と陰極電解帯を各々２ケ所づつ交互に連続配置した例である。この場合、電源装置８を２個に分散できるので比較的小容量の電源装置でもよく、また上流側の陰極帯と下流側の陰極帯で電流の種類、電流密度を変えて組み合わせることも可能となる。ここで、上流側の電流密度を下流側のそれより大きくした前段負荷型にすると総投入電力が同じでもより多くの皮膜を生成可能である。これは、皮膜生成反応の後半では鋼材表面の過半に非導電性のリン酸塩の結晶が付着しており電流印加の効果が小さくなっているためと考えられる。
【００１４】
図３は図１の電流印加式のリン酸塩処理装置を組み込んだ線材の連続処理装置である。サプライスタンド２より引き出されたコイル状の鋼材１は伸線機１３を動力として長手方向に矯正機３、デスケーリング装置４、洗浄・予熱装置５を通過した後にリン酸塩処理槽３３へ移送される。
このリン酸塩処理槽３３には陽極電解帯６と陰極電解帯７が鋼材の経路に沿って備えられている。陽極電解帯６には電源装置８の陰極側が接続された陰極電極２１が、陰極電解帯７には電源装置８の陽極側が接続された陽極電極２２が各々リン酸塩処理液３４中に浸漬配置される。このとき、鋼材の通材方向に対して陽極電解帯６が陰極電解帯７の上流側となるよう配置され、電極は処理する鋼材の投影幅以上の大きさのものを鋼材を挟んで対面に直接鋼材に接触しないように配置することで鋼材周方向における皮膜量のばらつきを抑えることが可能である。
リン酸塩処理槽３３を出た鋼材１は洗浄・中和装置９、石鹸処理装置１０、乾燥装置１１を経過した後、伸線ダイス１２にて縮径され、捲取装置１４にて再度コイル状に巻き取られる。
また、上記連続処理装置のデスケーリング装置４にショットブラスト等のメカニカルデスケーリングにて脱スケールした場合、極微量ではあるものの除去しきれなかった鉄スケール、合金酸化物が鋼材表面に残存し、リン酸塩の付着を阻害するという問題があるが、本発明のリン酸塩処理槽内での陽極電解帯で完全除去が可能となる。
【００１５】
【実施例】
本発明の実施例を、鋼線材にリン酸亜鉛皮膜を形成させた場合について詳述する。
表１には図３の連続処理装置を用いて本発明法と従来法とを以下の条件で実施した結果について示す。ここで、鋼材表面に生成せしめたリン酸亜鉛皮膜の付着量を評価するため処理後の鋼材を酸性溶液に溶かすという方法でリン酸亜鉛皮膜量を測定した。リン酸亜鉛皮膜量はその用途により好適な値が選定されるが４〜２０ｇ／ｍ² の範囲が好ましい。また、鋼材とリン酸亜鉛皮膜の密着性を評価するため、処理材を孔型ダイスで伸線加工した後のリン酸亜鉛皮膜量を測定し、伸線前後の皮膜量からリン酸亜鉛皮膜の残存率を求めた。
【００１６】
（実施条件）
被処理材：ＪＩＳＳ４５Ｃ相当，直径７．５ｍｍ
デスケーリング：ショットブラスト
処理材予熱温度：８５℃
リン酸亜鉛処理：濃度３０〜８０ポイント，処理時間５秒

潤滑石鹸：石灰石鹸（固形分濃度１８％）
乾燥：熱風温度１５０℃，乾燥時間１０秒
伸線条件：仕上線径φ６．５ｍｍ（減面率２５％）
【００１７】
表１から明らかなように、本発明法による実施例１では６〜１４．５ｇ／ｍ² のリン酸亜鉛皮膜の付着量が確保され、更に伸線後も皮膜の８７％は鋼材表面に残存する優れた密着性が得られている。また実施例２は陽極電解帯と陰極電解帯からなる組の工程を２回行うので、実施例１よりも総投入電力が１０％少ないにもかかわらずほぼ同等の皮膜付着と密着性が得られた。また実施例３ではパルス電流の結晶粒微細化作用により伸線後の皮残存率は９０％にまで向上した。
【００１８】
【表１】

【００１９】
【発明の効果】
以上に述べたように、本発明法に従えば、電気的リン酸塩処理においても皮膜量の確保と、鋼材と皮膜の密着性を兼ね備えた優れた表面処理材を製造可能となったばかりか生産性向上による経済的効果や省力化にもたらす効果は極めて大きい。
【図面の簡単な説明】
【図１】本発明の陽極電解帯と陰極電解帯を各々１つづつ備えたリン酸塩処理方法と装置を示す概念図、
【図２】本発明の陽極電解帯と陰極電解帯を各々２つづつ備えたリン酸塩処理方法と装置を示す概念図、
【図３】本発明の電気的リン酸塩処理装置を組み込んだ線材の連続処理装置のブロック図、
【図４】従来法による電気的リン酸塩処理方法と装置を示す概念図である。
【符号の説明】
１鋼材
２サプライスタンド
３矯正機
４デスケーリング装置
５洗浄・予熱装置
６陽極電解帯
７陰極電解帯
８電源装置
９洗浄・中和槽
１０潤滑石鹸処理装置
１１乾燥装置
１２伸線ダイス
１３伸線機
１４捲取装置
２１電極（陰極）
２２電極（陽極）
３１通電ローラー
３２抑えローラー
３３リン酸塩処理槽
３４リン酸塩処理液[0001]
[Industrial application fields]
The present invention relates to an apparatus for forming a phosphate film by continuously passing a coiled steel material while rewinding it.
[0002]
[Prior art]
Conventionally, phosphating on steel materials has been widely used as a lubricant film base treatment, rust prevention treatment, and paint base treatment for parts processing. Phosphate treatment is generally carried out by dipping or spraying.
Therefore, when the steel material is immersed in the zinc phosphate treatment solution, the following reaction occurs.
(Anode reaction) Fe → Fe ²⁺ + 2e ⁻
(Cathode ^{^{reaction) 2H + + 2e - → H}} 2
Here, the anodic reaction is a dissolution corrosion reaction of the steel material surface by phosphoric acid, which provides electrons to the steel material surface and activates the steel material surface to ensure the adhesion between the phosphate crystal and the steel material surface. Moreover, the cathode reaction caused by the electrons given in the steel is a reaction that converts hydrogen ions separated and suspended in the solution into hydrogen molecules. The average pH of the treatment solution is around 2, but the pH rises to around 4 near the steel surface where the cathode reaction has occurred, satisfying the precipitation condition of zinc phosphate crystals (Zn ₃ (PO ₄ ) ₂ ), A zinc phosphate coating is formed on the steel surface.
(3Zn (H ₂ PO ₄ ) ₂ → Zn ₃ (PO ₄ ) ₂ + H ₃ PO ₄
[0003]
By using this zinc phosphate coating as a base treatment to form a lubricant coating composed of a metal soap such as stearate on the surface, the surface pressure is 3000 (MPa) as in cold forging, the friction surface temperature is 400 ° C., the surface area Even under harsh conditions in which the enlargement ratio is as high as 100 times, the friction force between the steel material and the mold can be lowered to prevent the mold from being worn or seized.
However, since the formation reaction of this zinc phosphate film is a complex reaction in which the electrochemical reaction, the equilibrium reaction associated with pH fluctuation, and the crystal precipitation reaction interact with each other, the film amount is sufficient due to the temperature, concentration, and component fluctuations of the solution. If it is not obtained or if the adhesiveness with the steel material is not sufficient, it causes a problem such as seizure in the cold forging process.
[0004]
In addition, the time required to uniformly treat the film adhesion state on the entire steel surface is 20 seconds even in a system in which a flat plate is immersed in a treatment tank, that is, even when the treatment liquid can be sufficiently replaced on the steel surface. In a system in which a steel material wound in a coil shape is immersed in a treatment tank for about 2 minutes from 1 to 3 minutes, that is, in a system in which the treatment liquid staying inside the coil is not sufficiently replaced, a long time of 3 to 8 minutes is required. In short, there was a problem in terms of productivity improvement. Thus, an electrical promotion method has been devised as one of the technologies for promoting phosphate treatment. Since the DC constant current method was disclosed in British Patent No. 16300 (1909) as an electrical acceleration technique for phosphating, an AC energization method (for example, Japanese Patent Publication No. 49-46220) or a pulse current application method (for example, Improvements such as JP 59-197596 A and JP 6-322592 A have been repeated.
[0005]
[Problems to be solved by the invention]
The electrical promotion method for phosphating has not been put into practical use because there is a problem that it is impossible to achieve both the securing of the coating amount and the adhesion to the steel surface.
When the cathode electrode is immersed in the phosphate solution in the opposite surface, the surface of the steel material is anodically electrolyzed and the anode reaction is selectively promoted. However, since there is almost no pH fluctuation due to the cathode reaction at this time, it is not possible to secure the amount of phosphate film formation, and zinc iron phosphate (Zn ₂ Fe (PO ₄ ) ₂ ) in which excessively eluted Fe ions are replaced with Zn ions. As a result, a film containing the main component as a main component is deposited, and the intended purpose cannot be achieved.
[0006]
Similarly, when the anode electrode is immersed in the phosphate solution in the opposite side, the surface of the steel material is subjected to cathodic electrolysis to promote the cathode reaction. As a result, sufficient pH fluctuation occurs, so that the precipitation of phosphate film formation can be increased according to the supply current. However, since there is no anode reaction, the adhesion between the steel material and the phosphate film is poor, and peeling occurs when parts are processed. As a result, there were problems such as burning the mold.
As a method for solving this problem, a method in which the current applied to the steel material is a pulse current or a forward / reverse reversal cycle current (for example, Japanese Patent Application Laid-Open No. 59-197596) is used to repeat the time zone for promoting the anode reaction and the cathode reaction. Although it is aimed at increasing precipitation of phosphate film formation by implementing it, in the case of cathodic electrolysis with pulse current, although a slight anode reaction can be expected during the current pause period, it is not fundamentally different from DC current . In addition, when the forward / reverse reversal cycle current is used, the coating at the site where the treatment was completed during anodic electrolysis is caused by local erosion of Fe at the interface between the deposited coating and the steel material by the anodic reaction during anodic electrolysis. As a result, there is a problem that the adhesion with the steel material is significantly hindered, and the intended purpose cannot be achieved.
[0007]
In addition, as a method of applying an electric current to a steel material, when applying the electrical promotion method while passing the steel material wound up in a coil shape such as a wire rod, a steel bar, a steel plate, a pipe, etc., as shown in FIG. The steel material 1 is immersed in the phosphating solution 34 by holding rollers 32 arranged on the entry side and the exit side of the acid treatment tank 33. Here, the power supply device 8 is in direct contact with the steel material by the energizing roller 31 or the energizing brush, and between the electrode 21 disposed so as to face the steel material in the phosphate solution 34 along the material passing direction. A direct current energization method for applying a current to the steel material 1 is employed. However, this method inevitably causes a surface defect such as unevenness or bending of the steel material, or electric discharge to the steel material due to wear on the surface of the current roller or brush, etc. There was a problem of doing.
The objective of this invention is providing the surface treatment apparatus of the steel materials which enables the phosphate film production | generation of the steel materials excellent in adhesion control in a very short time.
[0008]
[Means for Solving the Problems]
The gist of the present invention is as follows.
(1) In a steel surface treatment apparatus for forming a phosphate film on the surface of a steel material by applying an electric current while continuously passing the steel material through the phosphate treatment liquid, Arrange a pair of cathode electrodes and anode electrodes adjacent to each other along the path so that each cathode electrode is on the upstream side in the threading direction. (Length of cathode electrode threading direction / direction of anode electrode threading) (Length) ratio is 0.2 to 0.3, each electrode is disposed at a position not in contact with the passing steel material, and the cathode electrode and the anode electrode in each pair are simply a DC constant current or a pulse current. A steel material surface treatment apparatus characterized in that it is electrically connected via a single power supply device, and the current can be individually applied between each pair without direct contact between the electrode and the steel material. is there.
[0009]
In the present invention, a cathode electrode is arranged upstream of the steel material passing direction in the phosphating solution, and an anode electrode is arranged downstream of the steel material so that the steel material is continuously treated. Since the cathode reaction can be carried out in the cathodic electrolysis zone using the anode electrode after the anodic electrolysis zone using the cathode electrode, a film having good adhesion can be formed in a short time.
In addition, the present invention is superior in that it can supply electricity most efficiently when a DC constant current is applied, so that the processing time can be shortened and the electrode surface area can be minimized. In addition, when the pulse current is used, the amount of electricity that can be supplied is less than the direct current because there is a current quiescent period, but the phosphate film crystals formed on the surface of the steel material become denser and the adhesion to the steel material is improved. To do. That is, in the pulse current, the pulse average current density (ip × θ), which is the product of the current density (ip) during energization and the ratio (θ) in which current flows during one week, is equal to the current density of the DC constant current, In addition, the phosphating solution near the steel surface is replaced during the current suspension period of the pulse current, and when the current flows again, a new starting point for film crystal precipitation occurs, and the crystal grains become dense and refined. Conceivable.
In addition, the present invention can apply an electric current to the steel material without directly contacting the steel material and the electrode by connecting the adjacent electrodes immersed in the phosphating solution along the path through a power supply device. In addition, it is possible to prevent the occurrence of holes and wrinkles on the steel surface. In addition, the anodic electrolysis zone and the cathodic electrolysis zone can be efficiently formed in the phosphate treatment tank using only a single power supply device.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Next, an embodiment of the present invention will be described.
The steel materials to which the present invention is applied can be applied not only to hot-rolled materials and annealed materials, but also to steel materials that have been galvanized on the surface, and all steel materials that can be phosphated in principle. .
The phosphate referred to in the present invention contains one or more of zinc phosphate, nickel phosphate, calcium phosphate, and iron phosphate.
The current applied to the steel product by the present invention is a DC constant current or pulsed current, the DC constant current is preferably a current density in the range of 50~200000A / m ^2,. When the current density is lower than this range, almost no promotion effect can be expected by applying current. When the current density exceeds this range, the mass transfer of the treatment liquid will limit the film formation rate, so even if the current value is increased, the promotion effect is achieved. This is because there is no influence on.
[0011]
The present invention will be described in more detail with reference to the illustrated examples. FIG. 1 is a side view of an example of a current application type phosphating apparatus according to the present invention. An electrode 21 is electrically connected to the phosphate treatment tank 33 via the power supply device 8 so as to perform anodic electrolysis on the upstream side in the steel material passing direction and cathodic electrolysis on the downstream side. The steel material 1 moves from the left side of the figure and is guided by the roller 32 to the phosphating bath 33 and immersed in the phosphating solution 34. The steel material is anodically electrolyzed by the electrode 21 connected to the cathode side of the power supply device 8, and an anodic reaction occurs abruptly to activate the steel material surface. Thereafter, the steel material is catholyzed by the electrode 22 connected to the anode side of the power supply device 8 to cause a cathode reaction, whereby the pH of the treatment liquid in the vicinity of the steel material rises and a film crystal is deposited in a very short time. As a result, it is possible to obtain a phosphate film that ensures both the amount of film adhesion and the adhesion to the steel surface.
[0012]
Here, since the total current value of the anodic electrolysis zone and the cathodic electrolysis zone is equal, if the lengths of both zones are equal, the current density on the steel surface is equal, and if the electrolysis zone lengths are different, the current is inversely proportional to the electrolysis zone length. Density decreases. Therefore, if the lengths of the anodic electrolysis zone and the cathodic electrolysis zone are extremely different, each electrolytic reaction cannot be performed efficiently. In addition, since the cathode electrolysis zone requires more time for precipitation of phosphate crystals, the ratio of the length of the anodic electrolysis zone to the cathode electrolysis zone is in the range of 0.2 to 0.3: 1.0 . preferable.
In addition, although the electrode material is a carbon electrode, good results were obtained. However, if it is a metal, it can be made of a so-called noble metal such as platinum, titanium, iridium or its oxide, so that the electrode can be used during an electrolytic reaction. Can be prevented from eluting into the phosphate solution.
[0013]
FIG. 2 is a side view of another example of the phosphating apparatus of the current application type according to the present invention. This is an example in which an anodic electrolysis zone and a cathodic electrolysis zone are alternately and continuously arranged in two places in the phosphating tank 33. In this case, since the power supply device 8 can be distributed to two, a power supply device having a relatively small capacity may be used, and it is also possible to combine the upstream cathode band and the downstream cathode band by changing the type of current and the current density. Become. Here, if the upstream load current density is made larger than that on the downstream side, more films can be generated even if the total input power is the same. This is presumably because in the latter half of the film formation reaction, non-conductive phosphate crystals adhere to the majority of the steel material surface, and the effect of current application is reduced.
[0014]
FIG. 3 shows a continuous processing apparatus for a wire rod incorporating the current application type phosphate processing apparatus of FIG. The coiled steel material 1 drawn out from the supply stand 2 is transferred to the phosphating tank 33 after passing through the straightening device 3, descaling device 4 and cleaning / preheating device 5 in the longitudinal direction by using the wire drawing machine 13 as power. The
The phosphating tank 33 is provided with an anodic electrolysis zone 6 and a cathodic electrolysis zone 7 along the path of the steel material. A cathode electrode 21 connected to the cathode side of the power supply device 8 is immersed in the anodic electrolytic zone 6, and an anode electrode 22 connected to the anode side of the power supply device 8 is immersed in the phosphating solution 34. Is done. At this time, the anodic electrolysis zone 6 is disposed upstream of the cathodic electrolysis zone 7 with respect to the passing direction of the steel material, and the electrodes are opposed to each other across the steel material with a size larger than the projected width of the steel material to be processed. It is possible to suppress variations in the coating amount in the circumferential direction of the steel material by arranging so as not to directly contact the steel material.
After passing through the washing / neutralizing device 9, the soap treatment device 10, and the drying device 11, the steel material 1 exiting the phosphate treatment tank 33 is reduced in diameter by the wire drawing die 12, and again coiled by the scraping device 14. Rolled up into a shape.
In addition, when descaling is performed on the descaling device 4 of the above-described continuous processing device by mechanical descaling such as shot blasting, iron scale and alloy oxides that are extremely small but could not be removed remain on the surface of the steel material, and phosphorus Although there is a problem of inhibiting the adhesion of the acid salt, it can be completely removed by the anodic electrolysis zone in the phosphate treatment tank of the present invention.
[0015]
【Example】
Examples of the present invention will be described in detail with respect to the case where a zinc phosphate film is formed on a steel wire.
Table 1 shows the results of carrying out the method of the present invention and the conventional method under the following conditions using the continuous processing apparatus of FIG. Here, in order to evaluate the adhesion amount of the zinc phosphate film formed on the steel material surface, the zinc phosphate film amount was measured by a method of dissolving the treated steel material in an acidic solution. A suitable value for the amount of zinc phosphate coating is selected depending on its use, but a range of 4 to ²⁰ g / m ² is preferred. In addition, in order to evaluate the adhesion between the steel material and the zinc phosphate coating, the amount of zinc phosphate coating after the treatment material was drawn with a hole die was measured, and the amount of zinc phosphate coating before and after wire drawing was measured. The survival rate was determined.
[0016]
(Implementation conditions)
Material to be treated: JIS S45C equivalent, diameter 7.5mm
Descaling: Shot blasting material preheating temperature: 85 ° C
Zinc phosphate treatment: concentration 30-80 points, treatment time 5 seconds

Lubricating soap: Lime soap (solid content 18%)
Drying: Hot air temperature 150 ° C., drying time 10 seconds Drawing condition: Finished wire diameter φ6.5 mm (area reduction rate 25%)
[0017]
As can be seen from Table 1, in Example 1 according to the method of the present invention, an adhesion amount of 6 to 14.5 g / m ² of zinc phosphate film was secured, and 87% of the film remained on the steel surface even after wire drawing. Excellent adhesion is obtained. In addition, since Example 2 performs the process of a set including an anodic electrolysis zone and a cathodic electrolysis zone twice, almost the same film adhesion and adhesion can be obtained even though the total input power is 10% less than that in Example 1. It was. Further, in Example 3, the remaining rate of the skin after wire drawing was improved to 90% due to the grain refinement effect of the pulse current.
[0018]
[Table 1]

[0019]
【The invention's effect】
As described above, according to the method of the present invention, it has become possible not only to produce an excellent surface treatment material that has both the amount of coating and the adhesion between steel and coating even in electrical phosphate treatment. The effect of improving the economic efficiency and labor saving is extremely large.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram showing a phosphating method and apparatus having one anodic electrolysis zone and one cathodic electrolysis zone according to the present invention,
FIG. 2 is a conceptual diagram showing a phosphating method and apparatus provided with two anodic electrolysis zones and two cathodic electrolysis zones according to the present invention,
FIG. 3 is a block diagram of a continuous processing apparatus for wire incorporating the electrical phosphate processing apparatus of the present invention;
FIG. 4 is a conceptual diagram showing an electrical phosphating treatment method and apparatus according to a conventional method.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Steel 2 Supply stand 3 Straightening machine 4 Descaling apparatus 5 Cleaning / preheating apparatus 6 Anode electrolysis zone 7 Cathode electrolysis zone 8 Power supply device 9 Washing / neutralization tank 10 Lubricating soap treatment apparatus 11 Drying apparatus 12 Wire drawing die 13 Wire drawing machine 14 Trapping device 21 Electrode (cathode)
22 Electrode (Anode)
31 Energizing roller 32 Retaining roller 33 Phosphate treatment tank 34 Phosphate treatment liquid

Claims

In steel surface treatment equipment that forms a phosphate film on the steel surface by applying an electric current while continuously passing the steel material through the phosphating solution, along the path of the steel material in the phosphating tank The cathode electrode and anode electrode adjacent to each other are arranged so that each cathode electrode is on the upstream side in the material passing direction, and the ratio of the cathode electrode passing direction length / the anode electrode passing direction length 0.2 to 0.3, each electrode is placed at a position where it does not come into contact with the passing steel material, and the cathode electrode and anode electrode in each pair are a single power supply device that supplies a DC constant current or pulse current. A surface treatment apparatus for steel material, which is configured to be electrically connected to each other without allowing direct contact between the electrode and the steel material, and allowing individual current application between each pair.