JP3804860B2

JP3804860B2 - Recycling method for consumable members of vertical roll mill

Info

Publication number: JP3804860B2
Application number: JP2002212181A
Authority: JP
Inventors: 基浩安井
Original assignee: Kurimoto Ltd
Current assignee: Kurimoto Ltd
Priority date: 2002-07-22
Filing date: 2002-07-22
Publication date: 2006-08-02
Anticipated expiration: 2022-07-22
Also published as: JP2004050240A

Description

【０００１】
【発明の属する技術分野】
本発明は竪型ロールミルの消耗部材、とくにテーブル、ロールの摩耗退入後の再生方法に係る。
【０００２】
【従来の技術】
竪型ロールミルは多岐に亘る工業分野、たとえば石炭火力発電用の石炭微粉砕やセメント原料用の石灰石、クリンカーの微粉砕に使用されている。竪型ロールミルの粉砕原理は図６に略示するように、粉砕室ローラ内に回転自在に据え付けられたテーブル１の上面へ自ら転動可能にロール２を吊支し、ロール２はジャーナルアッセンブリー３によって室内で傾動自在に保持されているが、この図の例では油圧シリンダ３１が基盤とジャーナルアッセンブリー３とを結んで取り付けられ、油圧シリンダ３１の伸縮によってピボットピン３２を軸として回動し、ジャーナルアッセンブリー３に軸支されたロール２も共動きする。被砕物は粉砕室の上部よりチャージされてテーブル１の中央から遠心力によって外周へ寄せられ、ロール２とテーブル１間の粉砕空間Ｃ内で圧下摺動されて粉化して外側へ押出される型式が一般である。
【０００３】
粉砕空間Ｃはテーブル１とロール２との対向する隙間によって形成される。両部材が新品のときには図８（Ａ）のように粗粉を受入れる始端に相当するミルセンター側（図の右側）の隙間Ｓ₁が最も広く、左方へ向かうにつれて隙間は次第に縮小して粉砕空間を形成しつつ隙間Ｓ₃を保った粉砕空間終端で開口する。このような粉砕空間Ｃの設定は最も粉砕効率が高く粉砕コストが極小になるように被砕物の種類、物性（硬度、耐圧力、粘性など）や目標とする粉砕後の粒度分布などを勘案して近接点を決め、粉砕空間Ｃの隙間Ｓ_２が最小となるように原材料毎に個別にそれぞれ調整される。なお、近接点の位置は図８のものに拘らず、Ｓ_２とＳ₃が同じ長さ、すなわち図におけるＳ₃が近接点となることもある。また、図９（Ａ）のように粉砕面の断面が傾斜した直線で形成され、始端の隙間Ｓ₁が最大で、終端の隙間Ｓ_２が最小となって開口する場合もあり、近接点の調整と共に被砕物や運転状況などによりさまざまな粉砕面の形状を取り得る。
【０００４】
この型式の粉砕条件で問題となるのが、ロールおよびテーブルの摩耗後退である。摩耗が粉砕面全面に亘って均等に進行するのであれば、ロールとテーブルの相対的な関係はジャーナルアセンブリー機構の下方への付勢作用によって常に一定に保たれるから実質的な弊害はほとんど皆無であるが、実際には両者表面では不均等な偏摩耗が進行して、当初設定した粉砕面とは異なる歪つな曲面となって粉砕条件が大幅に悪化し、所定の効率が持続できなくなって予定を下回る実績しか挙げられなくなる。図８（Ｂ）はこの関係を例示した断面図であって、図の右側から被粉砕品が装入され左側から粉体として押し出される経過を続ける間に、テーブル、ロールともに不均等な摩耗が進み、最初の点線Ｍの位置から摩耗によって実線Ｎの位置まで偏った後退をすると、粉砕空間Ｃの構成が逆転し粉砕作用に貢献しない両側の間隙が狭くなり、実質的に粉砕作用が発揮される中央部が歪つに変形して粉砕効率は目に見えて低下する。また、図９（Ａ）に示すロールとテーブルの場合であっても同様に、図９（Ｂ）のように歪な粉砕面を形成していく。
【０００５】
効率の低下したテーブル、ロールは現地において取り替えるときわめて煩瑣な分解、取り外し、取り付けの作業を強いられ、その間、プラントは停止せざるを得ないため多大の労力と時間の浪費を余儀なく強いられるので、従来から特殊な硬化溶接肉盛法を用いて消耗部材を一定期間毎に再生復元する技術が開発され大きな成果を挙げている。
【０００６】
出願人は先に特公平７−４６６４号において竪型ロールミルのテーブル再生について、また特公平７−１０２４５６号においてロール再生について、それぞれ独自の再生方法、とくに現地の竪型ロールミルにおいて消耗した部材を取り外さないでそのまま完全な溶接肉盛が実施できるような特殊な装置と手順を提示し、発電プラントやセメント業界などの分野において、摩耗退入したテーブルやロールの摩耗面を溶接肉盛によって元の形状に回復させ、再び新品と同じ粉砕効率を取戻して高い評価を受けてきたのである。
【０００７】
さらに特開平１１−３０９５９６号公報において、多層肉盛可能な多層肉盛層を重ねて最高の粉砕効率を約束する元の粉砕面（理想粉砕面；取付け当初の粉砕面）の形状に回復し、その上へ多層肉盛は困難だが超高硬度のマトリックスを形成するワイヤを溶着しつつその溶融プール内へタングステン炭化物粉体を添加分散した超硬肉盛層を形成する手順よりなる再生方法を開示した。これによって独特の不均等な曲線を描いて摩耗退入していく摩耗線が高効率の粉砕空間から乖離するのを極力抑止して竪型ロールミル全体の粉砕能力をレベルアップしたと謳っている。
【０００８】
前記従来技術の他、硬度の異なる複数種の材質によって溶接肉盛層を複合化する技術としては、たとえば特開昭５６−７３５５３号公報では普通鋳鋼（ＳＣ４６等）でローラ本体を鋳造し、第１層に硬さが従来の耐摩耗特殊鋳鉄よりも大きい合金材を肉盛溶接し、その上の第２層に軟質で靭性の高い加工硬化性の合金材を肉盛溶接してローラ表面を形成する工法を開示し、技術的な評価は別として前記の従来技術とは逆の構成からなっており、第２層（表面層）が第１層（内面層）の高硬度合金材に支えられて高衝撃を受けるごとに加工硬化されて耐摩耗性を向上し、この結果、従来のように表面が摩耗すると急激に摩耗速度が大きくなることはなくなると謳っている。
【０００９】
また特開昭５５−１６５１４９号公報に係る従来技術では、先の引用例とは反対にローラ粉砕面（普通鋳鋼）に溶着が下層より上層へ順次高硬度となるように表面硬化肉盛溶接を施している。従来のＨv７００〜８００にも達するＮｉ−Ｃｒ合金鋳鉄のローラに代え、靭性に富む普通鋳鋼を母材とし、その表面上へ第１層はＨv３５０〜４５０、その上の第２層はＨv３５０〜６５０、その上へＨv７５０〜９５０と、順次硬度を上げた複数種の肉盛溶接層を積層することによって、溶接時の亀裂、破損の欠陥が出難くしたとしている。相互に溶接性のよい積層を重ねて最終的に高硬度の表面に至るという困難な溶接条件をクリアする努力の跡は評価できる。
【００１０】
【発明が解決しようとする課題】
図８（Ｂ）に示す摩耗パターンは、消耗部材の部位によって摩耗退入の進行速度（摩耗深さ）に大きな違いがあることを明示し、粉砕に最も大きく関与する部位が最も摩耗退入量も多いことを示している。特開平１１−３０９５９６号に係る従来技術は、この特徴に着目して理想粉砕面を少しでも長く保持することを要旨とし、多層肉盛で回復した理想粉砕面の表面に超硬肉盛層を形成しているから、再生後の使用時においても粉砕に伴う初期摩耗に強く、長い間、理想の粉砕面を維持できることは事実である。しかし、長短の差があるとはいえ無限にこの状態を維持できるわけではなく、いつかは最も摩耗作用の過酷な箇所で表面の超硬肉盛層が破られるときが来ることは免れない。そして一旦、破られると、比較的硬度の低い硬化肉盛層が露呈するから、硬度差のため、この部分を突破口として局部摩耗が急速に昂進する可能性がある。したがって従来の不均等な摩耗線の前進に拍車を掛け、より不均等に深化した凹部が穿たれて折角他の曲面で元の理想粉砕面を維持していても粉砕効率に大きな悪影響を与える懸念があり、結局、再生後の使用期間の延長という目的を十分に果せない危惧が残る。
【００１１】
同じ課題は特開昭５６−７３５５３号や特開昭５５−１６５１４９号の従来技術についても残る。特に前者では如何に加工硬化が期待できようとも、軟質で靭性を重視した二重構造とするものであるから、高々Ｈv：１８０〜２３０程度の軟質表面では、稼働後、直ちに摩耗消滅の恐れが大きく、その後に現れた第２層は従来より高硬度とはいえ、それだけ脆性も大きいから多層盛りが困難であり、層厚に制約があって形状復元に必要な全肉盛層のうち、どれだけの範囲まで強化できるか、きわめて厳しい課題に直面せざるを得ない。また、後者は溶接条件の改善を特徴とするもので、内面に至るほど軟質とする特徴を要旨とするから、従来、全体としてＨv７００〜８００に均質化していたローラに対し、表面だけをＨv７５０〜８５０に硬化したとしても、その層が一旦、摩耗で破られれば以降は加速的に摩耗が昂進する粉砕面の構成であるから、果たして全体としての耐用期間が期待ほど向上するのであろうか、実用上は疑問の残る手段と言わざるを得ない。
【００１２】
本発明は以上述べたように摩耗した竪型ロールミルの粉砕面を溶接肉盛によって再生するに当り、従来技術のすべてが抱える危惧、すなわち一旦、粉砕面の表面層の一部でも摩耗によって破られれば、急速に歯止めなく摩耗が進行し始め、加速的に粉砕面の理想面を歪曲し粉砕機能を喪失するという共通の課題を解決し、最後までほぼ正常な粉砕機能を持続できる再生方法の提供を目的とする。
【００１３】
【課題を解決するための手段】
本発明に係る竪型ロールミルの消耗部材の再生方法は、不均等に退入した摩耗面上へ高硬度の溶加材Ｂを用いて最高の粉砕効率を具えた元の粉砕面にほぼ相似した軌跡を描いた硬化肉盛層Ｂ₁を形成し、該硬化肉盛層Ｂ₁の上へ前記高硬度よりもさらにＨv；３００以上高い硬度よりなる超硬肉盛層Ａ₁を前記軌跡とほぼ相似した軌跡を描いて前記硬化肉盛層Ｂ₁の層厚より小さく形成し、さらに該超硬肉盛層Ａ₁の上へ同様に硬化肉盛層Ｂ₂を、該硬化肉盛層Ｂ₂の上へ超硬肉盛層Ａ₂を形成するように、以下同じ手順を繰返して互い違いに硬化肉盛層Ｂと超硬肉盛層Ａとを前記粉砕面とほぼ相似した軌跡を以て重ね合わせて最表面を前記超硬肉盛層で形成した元の理想粉砕面の形状に回帰するこ手順によって前記の課題を解決した。
【００１４】
前記手順において使用する肉盛層のうち、超硬肉盛層Ａについては、マトリックスを形成するワイヤを溶接肉盛しつつ該マトリックス溶融プール内へタングステン炭化物粉粒体を２０〜４０重量％の割合で添加して分散した複合組織を形成することが望ましい態様である。または、タングステン炭化物の添加に代えて超硬肉盛層Ａを形成する溶加材Ａとして、重量％にしてＣ：４．５〜６．０％、Ｃｒ：２０．０〜３０．０％を含み、その他Ｍｏ、Ｎｂ、Ｖ、Ｂの１つ以上を含有し、残りＦｅ及び不純物よりなり、かつ、Ｈv：９００以上となる多成分系炭化物析出硬化型のものを適用してもよい。
【００１５】
図１から図４は本発明によって再生した竪型ロールミル粉砕面の摩耗の進行を示したものである。図１（Ａ）は本発明の再生方法によって元の理想粉砕面を再現した状態であり、図１（Ｂ）は図１（Ａ）の部分拡大図である。この図の例では超硬肉盛層Ａは４層、硬化肉盛層Ｂは３層、合計７層が互い違いに重なって全体として複合肉盛層を形成している。超硬肉盛層Ａと硬化肉盛層Ｂはそれぞれ特定の相似した曲面によって累積しており、この曲面は曲率半径が異なるだけの相似の曲線で形成して、最も粉砕効率が高くなる元の粉砕面とほぼ相似した表面を形成し、曲率半径を違えてほぼ同じ肉厚ピッチで繰返し積み重なる。
【００１６】
図１から再使用がスタートすると、この竪型ロールミル特有の摩耗アタックが始まり、まず最表層を形成する超硬肉盛層Ａ₄は抜群の耐摩耗性を発揮するが、時間の経過と共に遂に最も摩耗作用の厳しい箇所で破れ、下層の硬化肉盛層Ｂ₃が露呈し、図２のように凹部１２が現れる。しかし従来技術とは異なり、この凹部１２は硬化肉盛層Ｂ₃の摩耗が進んで下底部に達すると超硬肉盛層Ａ₃が露呈するので、縦方向に対する摩耗の進行はこの面で食い止められ、図３のように耐摩耗性が比較的低い硬化肉盛層Ｂ₃に添って横方向に広がる。このような作用が発生する要件としては、超硬肉盛層Ａと硬化肉盛層Ｂの硬度差がＨv：３００以上あることで、これほどの硬度差がなければ、硬化肉盛層Ｂが全部摩耗し切るまでに超硬肉盛層Ａの何れかが破れて凹部の深化が始まる恐れがある。結局、図４のように縦方向（内部方向）への摩耗の進行は、硬化肉盛層Ｂ₃が全部摩耗し切るまで超硬肉盛層Ａ₃の面で阻止され、ほぼ元の理想粉砕面に再び戻る。
【００１７】
ここであらためて超硬肉盛層Ａ₃に対する摩耗が始まり、同じ経過を辿って超硬肉盛層Ａ₂が全部露呈するまで硬化肉盛層Ｂ₂が摩耗し尽されて元の理想粉砕面に戻る。このように互い違いに超硬肉盛層と硬化肉盛層が摩耗アタックを受けつつ、比較的浅い凹部の形成とその横への広がりに基づく元の理想粉砕面への回帰を繰返して、長い可使時間ときわめて小さい粉砕空間の変動による安定した粉砕効率の確保を続ける作用が発現するのである。
【００１８】
この超硬肉盛層Ａは超高硬度の反面、靭性に乏しく、成形層の厚さを増加するために無理に多層盛りを強行すると、大きな亀裂と剥離が生じ、実機に取付けて粉砕運転すると却って耐用期間が短縮し、目的に反することがある。その制約からも超硬肉盛層Ａは１〜３層までの薄肉に留め、層厚として前記硬化肉盛層Ｂの２／３以下であることが求められる。例えば、図５のように最表層の超硬肉盛層Ａ_４はａ_４１からａ_４３までの薄層を重ねて形成し、その下層の硬化肉盛層Ｂ_３はｂ_３１からｂ_３５までの５層を重ねて必ずＡ_４の３／２倍以上の層厚を形成することが要件である。互い違いに介在する硬化肉盛層Ｂは超硬肉盛層Ａの亀裂による剥離脱落を繋ぎ止める止着材の役割を果すが、超硬肉盛層からの成分が希釈することによって自らの靭性を失うことを防ぐために、双方の肉厚間に一定の制限を設けることが望ましい。
【００１９】
【発明の実施の形態】
前記のように図１は本発明の実施形態を示す要部の断面図で、テーブル１の摩耗部分に対し、硬化肉盛層Ｂと超硬肉盛層Ａとを互い違いに重ねて多層複合化して元の理想粉砕面の形状に回帰した状態である。ここでローラ２についても同様の処置を講じるが、図の上では省略している。硬化肉盛層を形成する溶加材Ｂとしては公知のＣ：３．０〜７．０％、Ｓｉ：０．５〜２．５％、Ｍｎ：０．５〜３．０％、Ｃｒ：２０．０〜３５．０％、残りＦｅ及び不純物よりなる高クロム系肉盛層を形成できるフラックスコアドワイヤなどを適用した自動連続溶接法を使用すればよい。
【００２０】
硬化肉盛層Ｂ₁の上面へ超硬肉盛層Ａを溶接肉盛する。この場合の要件は硬度差がＨvにして３００以上あることで、超硬肉盛層のベースとなる溶加材Ａは前記の溶加材Ｂよりも硬度の高い高Ｃｒ系鋳鉄肉盛材を適用すると共に、図７に例示するような溶接装置によってワイヤを送り込みつつ、溶融プールの中へタングステン炭化物を一定割合で添加し、薄肉ながら抜群の高耐摩耗性を具えた超硬肉盛層Ａ₁を形成する。硬度差がＨv：３００以下の場合には、過去の経験から見て必ずしも理想的な粉砕面を持続できる保証がなく、本発明の目的から外れる可能性が大きいので避けるべきである。
【００２１】
この場合の溶接条件の一例としては、
1.溶接電流４００Ａ
2.溶接電圧３０Ｖ
3.走行速度２２００ｍｍ／ｍｉｎ
4.層間温度３００℃以下
5.入熱量３２７３Ｊ／ｃｍ
6.タングステン炭化物Ｗ：８７．０％，Ｃ：５．７％，Ｃｏ：６．７％を主成分とする粒径０．４〜０．９ｍｍのペレット
7.タングステン炭化物投下量１．８ｋｇ／ｈｒ
8.タングステン炭化物充填率２５〜３５％
9.超硬薄肉層の層厚１層で、約４ｍｍ
10.使用ワイヤＣ：６．０％，Ｃｒ：２８．０％を主成分とするフラックスコアドワイヤ。
かつ、シールドガスを使用せず、予熱および後熱もなく薄肉ながら超高硬度の表面層を形成する。タングステン炭化物の充填率の制限は重要な要素で、この実施例では２５〜３５％としたが、２０％以下では所望の硬度差（Ｈv：３００以上）が得られず、また４０％を超えると薄い肉盛層でも全面盛りはかなり難しく、現に溶着成分としてＷを４２〜５６％含む肉盛溶接棒（銘柄名；ＷＦ−９５０，１０００）も市販されているが、「溶着金属は割れが生じやすく多層盛りはできません。」と仕様制限を明記しているようにＷの添加上限は４０％とせざるを得ない。この銘柄の使用例としては浚渫用カッターヘッドのエッジへ筋盛り（相互の間隔を空けて筋状に肉盛すること）が推奨されている。
【００２２】
本例では硬化肉盛層も超硬肉盛層も何れも装置の簡略さや現地施工の軽便さから複合ワイヤを使用するオープンアーク溶接法を採用した。ロールの材質はＣｒ２７％をふくむ白銑鋳鉄が公知の耐摩耗材としては最も定評があるので、肉盛再生する溶接部もほぼ同一の材質で復元するのが最も望ましい。溶接デポジットをこの材質の中で硬化肉盛層と超硬肉盛層の硬度差が実現できるという条件の元にそれぞれ選定し、なおワイヤによる連続自動溶接を可能とするために、本例ではフラックスコアドワイヤを使用した。すなわちワイヤの軸芯を中空とし、この中空部にクロム，炭素など所望の添加成分の粉末を充填し、ワイヤ自体は可撓性を有する材質とし、溶接時に反応して母材とほぼ等しい成分を溶製するものである。
【００２３】
硬度差を実現するためには、超硬肉盛層、硬化肉盛層共に高Ｃｒ鋳鉄系の炭化物析出型のマルテンサイト相をベースとしながらも、その析出の割合や成分比率を調整した基地の差をだす上、この実施例のようにタングステン炭化物（ＷＣ）の添加によってマトリックス中へ粒体に含まれたタングステンおよび炭素などの一部が拡散し、タングステン炭化物特有の魚骨状の炭化物を分散した組織とする方法が推奨できる。溶融プール中へ少量のタングステンと炭素が溶出することによって、マトリックス自身の硬度も単一相に比べて飛躍的に増加し、ビッカース硬度Ｈｖ１１００にも達することもあり得る。加えてマトリックス中に分散し残留するタングステン炭化物の粒自体のビッカース硬度はおよそＨｖ２６００にも達する。これから肉盛面全体の見かけの硬度を計算すると
【００２４】
【数１】

となる。
【００２５】
超硬肉盛層Ａを形成する別の実施形態としてタングステン炭化物の分散硬化に代えて溶加材自体の強化によることも可能であり、多成分系炭化物析出硬化型の溶加材を適用する。Ｍｏ，Ｎｂ，Ｂ，Ｖの一種以上の添加は一挙に硬度を向上し、ビッカース硬度Ｈｖ９００以上を得るが、同時に脆性も増大するため、溶接肉盛層の層厚は１０〜１５ｍｍ程度まで、すなわち以下に列挙する溶接条件によっても１〜３層までの積層に留めることが重要な要件であり、それ以上の多層溶接肉盛は溶着部に大きな割れ、亀裂を誘発し、使用中の剥離脱落を呼ぶ主な原因となる懸念が否定できない。
この場合の溶接条件の一例としては、
1.溶接電流４５０Ａ
2.溶接電圧３０Ｖ
3.走行速度１５００ｍｍ／ｍｉｎ
4.層間速度３００℃以下
5.入熱量５４００Ｊ／ｃｍ
6.超硬薄肉層の層厚３層で、１１ｍｍの範囲
7.使用ワイヤ主成分はＣ：５．１％，Ｍｎ：０．７％，Ｓｉ：０．５％，Ｃｒ：２１．０％，Ｎｂ：６．７５％，Ｂ：０．８％，残Ｆｅ及び不純物よりなる２．８ｍｍのフラックスコアドワイヤ。
【００２６】
本発明の効果を確認するため実際に現地で粉砕作業に供用されている竪型ロールミルのテーブルおよびローラの粉砕面を肉盛溶接で構成して実験中であり、結果の詳細を知るには次期の肉盛再生まで多少の稼働時間を待たなければならないが、大まかな感覚としては粉砕面の摩耗退入分は、表面１層のみを超硬肉盛層で形成し内面層を全て高Ｃｒ鋳鉄系の硬化肉盛層で形成した従来技術に比べて、ほぼ３０％程度少ないように把握されている。
【００２７】
先に行なったラバーホィル摩耗試験（ＲＷＡＴ法；特開平４−３７１３９０号表１参照）によれば、表面層を高Ｃｒ鋳鉄系のマトリックスとしタングステン炭化物粒子を溶融プールに添加した超硬肉盛層とした場合と、通常の高Ｃｒ鋳鉄系の多層肉盛層とした場合をそれぞれ試験片とし、荷重下で回転しつつ６号珪砂で摩耗試験したところ、摩耗量は前者が２０．６ｍｇ、後者が１０２．６ｍｇで、ほぼ１：５の摩耗倍数が表れていたが、このラボテストから類推すれば、図１の実施例のように超硬肉盛層Ａが４層（層厚は層Ｂの２／３）、硬化肉盛層Ｂが３層で形成され、図２〜図４の経過を辿って摩耗退入するものとし、表面の１層のみをＡ層、残り全てをＢ層で形成する従来技術を比較例として、すべての肉盛層が摩耗消滅するまでの時間を（肉厚／摩耗倍率）で単純に計算すれば、
本願実施例では
（２／３）×４＋３／５＝４９／１５≒３．２６
比較例では
２／３＋〔３×（２／３）＋３〕×１／５＝２５／１５≒１．６７
となり、本発明の場合では約５１％の耐用時間の延長と算出されてテスト中の実感とは若干の違いが認められる。もっとも理論的には時間の経過と共に両者間の差は広がって行く可能性が高いとも言える。
【００２８】
【発明の効果】
本発明は以上に述べた通り、竪型ロールミルの消耗部材、とくにテーブル、ロールの溶接肉盛による再生に当り、従来の画一的な多層肉盛層の再生、乃至は最表層などを部分的に強化しただけの複合層による再生では超えられなかった耐用期間の限界を大幅に更新する効果が顕著である。すなわち、本発明の原理は多層肉盛が可能ではあるが耐摩耗性についてはなお不十分である硬化肉盛層と、多層肉盛が不可能ではあるが耐摩耗性が抜群である超硬肉盛層とを互い違いに重ね、しかもその複合層が形成する境界線は常に理想粉砕面と相似の軌跡を描いて成り立つように設定したから、独特の不均等な曲線を描いて摩耗退入していく摩耗線が理想の粉砕空間から乖離するのは、最大でも硬化肉盛層１層分の穿入に留まり、最も小さい変動の繰返しに抑制して常に理想粉砕面に近似した粉砕空間を持続することによって、望ましい粉砕効率を長く保持し続けて竪型ロールミル全体としての粉砕能力をレベルアップする効果がもたらされる。
【図面の簡単な説明】
【図１】図（Ａ）は本発明の再生方法によって元の理想粉砕面を再現した状態を示す要部の縦断正面図であり、図（Ｂ）は図（Ａ）の部分拡大図である。
【図２】本発明の実施形態における摩耗退入の経緯をを示す要部の縦断正面図である。
【図３】本発明の実施形態における摩耗退入の経緯をを示す要部の縦断正面図である。
【図４】本発明の実施形態における摩耗退入の経緯をを示す要部の縦断正面図である。
【図５】最表層の超硬肉盛層Ａ_４とその下層の硬化肉盛層Ｂ_３の要部の縦断正面図である。
【図６】竪型ロールミル全体を示す一部断面正面図である。
【図７】本発明の実施に使用する溶接装置の一例である。
【図８】従来技術における摩耗前（Ａ）と摩耗後（Ｂ）の状態を示す要部の正面断面図である。
【図９】他の従来技術における摩耗前（Ａ）と摩耗後（Ｂ）の状態を示す要部の正面断面図である。
【符号の説明】
１テーブル
２ロール
11 テーブル対向線
12 凹部
21 ロール中心線
Ａ₁、Ａ₂．．．超硬肉盛層
Ｂ₁、Ｂ₂．．．硬化肉盛層
ａ_４１、ａ_４２．．．超硬肉盛層Ａ₂の薄層
ｂ_３１、ｂ_３２．．．超硬肉盛層Ｂ_３の薄層
Ｓ₁ 粉砕空間始端の隙間
Ｓ₂ 粉砕空間最近接点における隙間
Ｓ₃ 粉砕終端の隙間[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a recycling method after wear-in / out of consumable members of a vertical roll mill, particularly tables and rolls.
[0002]
[Prior art]
The vertical roll mill is used in a wide variety of industrial fields, for example, fine pulverization of coal for coal-fired power generation, fine limestone for cement raw materials, and fine clinker. As shown in FIG. 6, the principle of crushing of the vertical roll mill is such that a roll 2 is suspended and supported on the upper surface of a table 1 rotatably installed in a crushing chamber roller, and the roll 2 is a journal assembly 3. In this example, the hydraulic cylinder 31 is attached by connecting the base and the journal assembly 3, and is rotated about the pivot pin 32 by the expansion and contraction of the hydraulic cylinder 31. The roll 2 supported by the assembly 3 also moves together. The material to be crushed is charged from the upper part of the crushing chamber, is brought to the outer periphery from the center of the table 1 by centrifugal force, is slid under pressure in the crushing space C between the roll 2 and the table 1 and is pulverized and pushed outward. Is common.
[0003]
The pulverizing space C is formed by a gap between the table 1 and the roll 2 facing each other. When both members are new, as shown in FIG. 8A, the gap S ₁ on the mill center side (the right side in the figure) corresponding to the starting end for receiving coarse powder is the widest, and the gap gradually shrinks toward the left and pulverizes. opening at milling space terminations with a gap S ₃ while forming a space. The setting of the pulverization space C takes into account the type of material to be crushed, physical properties (hardness, pressure resistance, viscosity, etc.) and target particle size distribution after pulverization so that the pulverization efficiency is the highest and the pulverization cost is minimized. determining a proximity point Te is adjusted individually for each raw material so that a gap S ₂ of milling space C is minimized. The position of the proximity points regardless to that of FIG. 8, S ₂ and S ₃ are the same length, that is, S ₃ in FIG sometimes become adjacent point. Further, as shown in FIG. 9A, the crushing surface may be formed by a straight line having a slanted cross section, and may be opened with the maximum gap S ₁ at the start end and the minimum gap S ₂ at the end. Various shapes of pulverized surfaces can be taken depending on the object to be crushed and operating conditions as well as adjustment.
[0004]
A problem with this type of crushing condition is the roll back of the rolls and tables. If the wear progresses evenly over the entire grinding surface, the relative relationship between the roll and the table is always kept constant by the downward biasing action of the journal assembly mechanism, so there is little substantial adverse effect. Although there is nothing, in reality, uneven wear on both surfaces progresses, resulting in a distorted curved surface that is different from the originally set grinding surface, greatly reducing the grinding conditions and maintaining the specified efficiency. It will be lost, and only results that are less than planned will be given. FIG. 8B is a cross-sectional view illustrating this relationship, and uneven wear occurs on both the table and the roll while continuing the process of inserting the product to be crushed from the right side of the figure and pushing it out as powder from the left side. If it moves forward and moves backward from the position of the first dotted line M to the position of the solid line N due to wear, the structure of the grinding space C is reversed and the gaps on both sides that do not contribute to the grinding action become narrower, and the grinding action is substantially exhibited. The central part is deformed distorted and the grinding efficiency is visibly reduced. Further, even in the case of the roll and the table shown in FIG. 9A, similarly, a distorted pulverized surface is formed as shown in FIG. 9B.
[0005]
If the tables and rolls with reduced efficiency are replaced in the field, they will be forced to disassemble, remove, and install, and during that time, the plant will have to be shut down, and so much labor and time will be wasted. Conventionally, a technique for regenerating and restoring a consumable member at regular intervals using a special hardening welding overlay method has been developed and has achieved great results.
[0006]
The applicant previously removed the worn members in the original vertical roll mill in Japanese Patent Publication No. 7-4664 for the table regeneration of the vertical roll mill and the roll recovery in the Japanese Patent Publication No. 7-102456. We present special equipment and procedures that enable complete weld overlay without any changes, and in the fields of power plants and cement industry, wear surfaces of worn-out tables and rolls are restored to their original shapes by weld overlay. And recovered the same grinding efficiency as a new product, and received high evaluation.
[0007]
Furthermore, in JP-A-11-309596, the shape of the original pulverized surface (ideal pulverized surface; initial pulverized surface) that promises the highest pulverization efficiency by stacking multilayered overlay layers that can be multilayered is restored. Disclosed is a regeneration method consisting of a procedure for forming a super-hard cladding layer in which tungsten carbide powder is added and dispersed in the molten pool while welding a wire that forms a super-hard matrix on top of which multi-layer overlay is difficult. did. It is said that this improved the crushing ability of the entire vertical roll mill by suppressing as much as possible the deviation of the wear line that draws a unique uneven curve from the high-efficiency crushing space.
[0008]
In addition to the conventional technique, as a technique for compounding the weld overlay by a plurality of materials having different hardnesses, for example, in Japanese Patent Laid-Open No. 56-73553, a roller body is cast with ordinary cast steel (SC46, etc.). Overlay welding of an alloy material that is harder than conventional wear-resistant special cast iron in one layer, and overlay welding a soft and tough work-hardening alloy material on the second layer The construction method to be formed is disclosed, and apart from the technical evaluation, the construction is opposite to that of the prior art, and the second layer (surface layer) is supported by the high hardness alloy material of the first layer (inner surface layer). It is said that every time it receives a high impact, it is work hardened to improve wear resistance, and as a result, when the surface is worn as in the prior art, the wear rate does not increase rapidly.
[0009]
In the prior art disclosed in Japanese Patent Application Laid-Open No. 55-165149, surface hardening overlay welding is performed so that the weld is gradually hardened from the lower layer to the upper layer on the roller pulverized surface (ordinary cast steel) contrary to the above cited example. Has been given. Instead of a conventional Ni-Cr alloy cast iron roller having a Hv of 700 to 800, the base material is a cast steel rich in toughness. The first layer is Hv350 to 450 on the surface, and the second layer is Hv350 to 650. On top of that, it is said that Hv 750 to 950 and a plurality of types of build-up weld layers with successively increased hardness are made difficult to cause cracks and breakage defects during welding. The trace of efforts to clear the difficult welding conditions of stacking layers with good weldability and finally reaching a high hardness surface can be evaluated.
[0010]
[Problems to be solved by the invention]
The wear pattern shown in FIG. 8B clearly shows that there is a large difference in the progress rate of wear retraction (wear depth) depending on the part of the consumable member, and the part that is most involved in crushing is the largest amount of wear retreat. There are also many. The prior art according to Japanese Patent Laid-Open No. 11-309596 focuses on this feature and keeps the ideal pulverized surface as long as possible. Since it is formed, it is true that it is resistant to initial wear associated with pulverization even during use after regeneration, and an ideal pulverized surface can be maintained for a long time. However, although there is a difference between long and short, this state cannot be maintained indefinitely, and it is inevitable that sometime the super hard overlay of the surface will be broken at the most severe part of the wear action. And once it is broken, a hardened layer with a relatively low hardness is exposed. Therefore, due to the difference in hardness, there is a possibility that local wear rapidly proceeds with this part as a breakthrough. Therefore, there is a concern that it will spur the advance of the conventional uneven wear line, and even if the concave portion deepened more unevenly is bored and the original ideal pulverized surface is maintained at the folding angle or other curved surface, the pulverization efficiency is greatly adversely affected. After all, there remains a concern that the purpose of extending the period of use after regeneration cannot be fully achieved.
[0011]
The same problem remains in the prior arts disclosed in JP-A-56-73553 and JP-A-55-165149. In particular, no matter how much work hardening can be expected with the former, since it has a double structure that is soft and emphasizes toughness, there is a risk of wear disappearing immediately after operation on a soft surface of Hv: about 180 to 230 at most. The second layer that appeared afterwards was harder than before, but its brittleness was so large that it was difficult to build a multilayer. It can only be strengthened to the extent that it can be strengthened, or it has to face extremely tough challenges. Further, the latter is characterized by improved welding conditions and is characterized by being softer toward the inner surface, so that only the surface of the conventional Hv 700-800 homogenous roller is Hv 750-800. Even if the layer is hardened to 850, once the layer is broken by wear, the wear surface is accelerated and wear is accelerated. The above is a questionable means.
[0012]
In the present invention, as described above, when the ground surface of a worn vertical roll mill is regenerated by welding overlay, there is a concern that all the prior art has, that is, even a part of the surface layer of the ground surface is broken by abrasion. For example, wear begins to progress rapidly without pausing, accelerating the common problem of distorting the ideal surface of the grinding surface and losing the grinding function, and providing a regeneration method that can maintain a nearly normal grinding function until the end. With the goal.
[0013]
[Means for Solving the Problems]
The method for regenerating the consumable member of the vertical roll mill according to the present invention was almost similar to the original grinding surface having the highest grinding efficiency using the high hardness filler material B on the unevenly retracted wear surface. forming a hardfacing layer B ₁ having a locus, further Hv than the high hardness onto cured overlay layer B _1; substantially carbide cladding layer a ₁ consisting of 300 or more high hardness and the track drawing a similar trajectory formed smaller than the thickness of the hardfacing layer B _1, further ultra-hard similarly hardfacing layer B ₂ onto the cladding layer a _1, cured buildup layer B ₂ In order to form the carbide overlay layer A ₂ on top of each other, the same procedure is repeated, and the cured overlay layer B and the carbide overlay layer A are alternately overlapped with a locus substantially similar to the pulverized surface. The said subject was solved by the procedure which returns the outermost surface to the shape of the original ideal grinding | pulverization surface formed with the said cemented carbide overlay.
[0014]
Among the overlay layers used in the above procedure, for the carbide overlay layer A, a ratio of 20 to 40% by weight of tungsten carbide powder particles in the matrix molten pool while welding the wires forming the matrix. It is a desirable embodiment to form a composite structure dispersed by adding in the above. Alternatively, as a filler material A for forming a super hard cladding layer A in place of the addition of tungsten carbide, C: 4.5 to 6.0%, Cr: 20.0 to 30.0% by weight% In addition, a multicomponent carbide precipitation hardening type that contains one or more of Mo, Nb, V, and B, consists of the remaining Fe and impurities, and has Hv: 900 or more may be applied.
[0015]
FIG. 1 to FIG. 4 show the progress of wear on the grinding surface of a vertical roll mill regenerated by the present invention. FIG. 1 (A) shows a state where the original ideal pulverized surface is reproduced by the regeneration method of the present invention, and FIG. 1 (B) is a partially enlarged view of FIG. 1 (A). In the example of this figure, 4 layers of the superhard overlay layer A, 3 layers of the hard overlay layer B, and a total of 7 layers are alternately overlapped to form a composite overlay layer as a whole. The superhard cladding layer A and the hardfacing layer B are accumulated by specific similar curved surfaces, and these curved surfaces are formed by similar curves with different curvature radii. A surface almost similar to the pulverized surface is formed, and repeatedly stacked with substantially the same thickness pitch with different curvature radii.
[0016]
When reuse starts from Fig. 1, the wear attack peculiar to this vertical roll mill begins. First, the super hard layer A ₄ that forms the outermost layer exhibits excellent wear resistance, but it finally becomes the most over time. It is torn at a place where the wear action is severe, and the underlying hardfacing layer B ₃ is exposed, and the recess 12 appears as shown in FIG. However, unlike the prior art, since the recess 12 is exposed is a carbide cladding layer A ₃ reaches the lower bottom portion proceeds wear of hardfacing layer B _3, progress of wear on the vertical direction halt in this respect As shown in FIG. 3, it spreads in the lateral direction along the hardfacing layer B ₃ having relatively low wear resistance. As a requirement for such an action to occur, the hardness difference between the carbide overlay layer A and the cured overlay layer B is Hv: 300 or more. If there is no such hardness difference, the cured overlay layer B is There is a possibility that any of the super-hard cladding layers A will be broken and the recesses will begin to deepen until they are completely worn out. Eventually, as shown in FIG. 4, the progress of wear in the longitudinal direction (inner direction) is prevented on the surface of the super-hard cladding layer A ₃ until the hard cladding layer B ₃ is completely worn out, and is almost the original ideal grinding. Return to the surface again.
[0017]
Here, wear on the carbide overlay layer A ₃ starts again, and the hard build-up layer B ₂ is worn out until the entire carbide build-up layer A ₂ is completely exposed through the same process. Return. In this way, while the carbide and hard cladding layers are alternately subjected to wear attack, the return to the original ideal grinding surface based on the formation of relatively shallow recesses and their lateral spread is repeated, allowing a long The effect of continuing to secure stable pulverization efficiency due to usage time and extremely small pulverization space fluctuations is manifested.
[0018]
While this super hard overlay A is super-hard, it is poor in toughness, and if it is forced to multi-layer forcibly to increase the thickness of the molding layer, large cracks and delamination will occur. On the other hand, the service life may be shortened and may be contrary to the purpose. Also from the restrictions, the super-hard-facing layer A is required to have a thin thickness of 1 to 3, and the layer thickness is required to be 2/3 or less of the hard-facing layer B. For example, as shown in FIG. 5, the outermost super hard overlay layer A ₄ is formed by stacking thin layers from a ₄₁ to a ₄₃ , and the lower hard build layer B ₃ is from b ₃₁ to b ₃₅ . it is a requirement always overlapped the 5-layer to form a layer thickness of at least 3/2 times the a _4. The stiffened build-up layer B intervening plays the role of a fastening material that prevents the flaking off of the super hard build-up layer A from cracking. However, the components from the super hard build-up layer dilute and increase their toughness. In order to prevent loss, it is desirable to have a certain limit between the wall thicknesses of both.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
As described above, FIG. 1 is a cross-sectional view of the main part showing an embodiment of the present invention. A hardened layer B and a super hard layer A are alternately stacked on the worn portion of the table 1 to form a multilayer composite. In this state, the shape has returned to the original ideal crushed surface shape. Here, the same measures are taken for the roller 2 but are omitted in the figure. As filler material B which forms a hardfacing layer, well-known C: 3.0-7.0%, Si: 0.5-2.5%, Mn: 0.5-3.0%, Cr: What is necessary is just to use the automatic continuous welding method which applied the flux cored wire etc. which can form the high chromium system overlaying layer which consists of 20.0-35.0%, remaining Fe and an impurity.
[0020]
The carbide cladding layer A to the upper surface of the hardfacing layer B ₁ to build-up welding. The requirement in this case is that the hardness difference is 300 or more in terms of Hv, and the filler material A serving as the base of the superhard cladding layer is a high Cr cast iron cladding material having a hardness higher than that of the filler material B. While applying the wire by a welding apparatus as illustrated in FIG. 7 and applying tungsten carbide to the molten pool at a constant rate, the super-hard cladding layer A having excellent wear resistance despite being thin. Form ₁ If the hardness difference is Hv: 300 or less, there is no guarantee that the ideal pulverized surface can be maintained from past experience, and it should be avoided because it is likely to deviate from the object of the present invention.
[0021]
As an example of welding conditions in this case,
1. Welding current 400A
2. Welding voltage 30V
3. Traveling speed 2200mm / min
4. Interlayer temperature 300 ° C or less
5. Heat input 3273J / cm
6. Tungsten carbide W: 87.0%, C: 5.7%, Co: pellets with a particle size of 0.4 to 0.9mm, mainly composed of 6.7%
7. Tungsten carbide drop 1.8kg / hr
8. Tungsten carbide filling rate 25-35%
9. The thickness of the super-thin layer is about 4mm
10. Wire used C: A flux cored wire mainly composed of 6.0% and Cr: 28.0%.
In addition, a shielding layer is not used, and a super-hard surface layer is formed while being thin without preheating and afterheating. The limit of the filling rate of tungsten carbide is an important factor. In this example, it is 25 to 35%. However, if it is 20% or less, a desired hardness difference (Hv: 300 or more) cannot be obtained, and if it exceeds 40%, Even a thin overlay layer is quite difficult to deposit on the entire surface, and an overlay welding rod (brand name: WF-950, 1000) containing 42 to 56% W as a welding component is also commercially available. The upper limit of W addition must be 40% as the specification limit is clearly stated. As an example of the use of this brand, it is recommended to streak to the edge of the scissors cutter head (to build up streaks with a space between each other).
[0022]
In this example, an open arc welding method using a composite wire was adopted for both the hardfacing layer and the superhard layering layer because of the simplicity of the equipment and the convenience of local construction. As the material for the roll, white cast iron containing 27% of Cr is the most well-known as a known wear-resistant material, and it is most desirable to restore the welded portion to be rebuilt using substantially the same material. In this example, the welding deposit is selected based on the condition that a hardness difference between the hardfacing layer and the cemented carbide layer can be realized. A core wire was used. That is, the wire core is hollow, and the hollow portion is filled with powder of a desired additive component such as chromium or carbon, and the wire itself is made of a flexible material, and reacts during welding with a component substantially equal to the base material. It is to be melted.
[0023]
In order to achieve the hardness difference, both the super hard cladding layer and the hard cladding layer are based on the high Cr cast iron carbide precipitation martensite phase, but the ratio of precipitation and the component ratio are adjusted. In addition to making a difference, as in this example, tungsten carbide (WC) is added to diffuse some of the tungsten and carbon contained in the particles into the matrix and disperse the fish-bone-like carbide peculiar to tungsten carbide. A recommended organization is recommended. By leaching out a small amount of tungsten and carbon into the molten pool, the hardness of the matrix itself can be dramatically increased compared to a single phase, and can reach Vickers hardness Hv1100. In addition, the Vickers hardness of the tungsten carbide grains themselves dispersed and remaining in the matrix reaches about Hv 2600. From this, the apparent hardness of the entire overlay surface is calculated.
[Expression 1]

It becomes.
[0025]
As another embodiment for forming the cemented carbide layer A, it is possible to reinforce the filler material itself instead of dispersion hardening of tungsten carbide, and a multi-component carbide precipitation hardening type filler material is applied. Addition of one or more of Mo, Nb, B, and V improves the hardness at once and obtains a Vickers hardness of Hv 900 or more, but at the same time, the brittleness also increases, so that the thickness of the weld overlay layer is up to about 10 to 15 mm, that is, Even with the welding conditions listed below, it is an important requirement to keep the stacking up to 1 to 3 layers. More than that, the multi-layer weld overlay induces large cracks and cracks in the welded part, causing peeling and dropping during use. Concern that is the main cause of calling cannot be denied.
As an example of welding conditions in this case,
1. Welding current 450A
2. Welding voltage 30V
3. Travel speed 1500mm / min
4. Interlayer speed 300 ° C or less
5. Heat input 5400J / cm
6.Thickness of super-thin layer 3 layers, 11mm range
7. Wire used Main components are C: 5.1%, Mn: 0.7%, Si: 0.5%, Cr: 21.0%, Nb: 6.75%, B: 0.8%, remaining A 2.8 mm flux cored wire made of Fe and impurities.
[0026]
In order to confirm the effect of the present invention, the table and roller crushing surface of the vertical roll mill actually used for crushing work in the field is being constructed by overlay welding, and the next term is to know the details of the results It is necessary to wait a little for the operation time until the build-up of the steel, but as a rough sense, for the wear-in / out of the crushed surface, only one surface layer is formed with a super hard layer and all inner layers are made of high Cr cast iron It is grasped to be about 30% less than the prior art formed with a hardened layer of the system.
[0027]
According to the rubber wheel wear test conducted previously (RWAT method; see Table 1 of JP-A-4-371390), a super hard cladding layer in which the surface layer is a high Cr cast iron matrix and tungsten carbide particles are added to the molten pool; And a normal high Cr cast iron-based multilayer overlay layer as test pieces, and a wear test with No. 6 silica sand while rotating under load, the wear amount is 20.6 mg for the former and the latter is At 102.6 mg, a wear factor of about 1: 5 appeared, but by analogy with this laboratory test, there are 4 superhard overlay layers A (layer thickness is 2 B of layer B) as in the example of FIG. / 3), the hardfacing layer B is formed of three layers, and wears and retreats following the course of FIGS. 2 to 4, and only one layer on the surface is formed with the A layer, and all the remaining are formed with the B layer. Using the conventional technology as a comparative example, until all the built-up layers wear out If simply calculated between at (thickness / wear ratio),
In this embodiment, (2/3) × 4 + 3/5 = 49 / 15≈3.26
In the comparative example, 2/3 + [3 × (2/3) +3] × 1/5 = 25 / 15≈1.67
Thus, in the case of the present invention, it is calculated that the service life is extended by about 51%, and a slight difference from the actual feeling during the test is recognized. Theoretically, the difference between the two is likely to widen over time.
[0028]
【The invention's effect】
As described above, according to the present invention, when a consumable member of a vertical roll mill, particularly a table, a roll is regenerated by welding build-up, the conventional uniform multi-layer built-up layer or the outermost layer is partially regenerated. The effect of drastically renewing the limit of the useful life that could not be exceeded by regeneration with a composite layer that has been strengthened to a large extent is remarkable. That is, the principle of the present invention is a hard-facing layer in which multilayer overlaying is possible but wear resistance is still insufficient, and a super-hard wall in which multilayer overlaying is impossible but wear resistance is outstanding Since the layered layers are alternately stacked, and the boundary line formed by the composite layer is always set so as to draw a trajectory similar to the ideal grinding surface, wear and retreat with a unique uneven curve. The amount of wear line that deviates from the ideal grinding space is limited to the penetration of one layer of hardened build-up layer at the maximum, and the grinding space that always approximates the ideal grinding surface is maintained by suppressing the smallest fluctuation. As a result, the desired crushing efficiency can be maintained for a long time, and the crushing ability of the entire vertical roll mill can be improved.
[Brief description of the drawings]
FIG. 1 (A) is a longitudinal front view of a main part showing a state where an original ideal pulverized surface is reproduced by a regeneration method of the present invention, and FIG. 1 (B) is a partially enlarged view of FIG. .
FIG. 2 is a longitudinal front view of a main part showing the history of wear and retraction in an embodiment of the present invention.
FIG. 3 is a longitudinal front view of a main part showing the history of wear retreat in the embodiment of the present invention.
FIG. 4 is a longitudinal front view of the main part showing the history of wear retreat in the embodiment of the present invention.
FIG. 5 is a longitudinal front view of the main part of the superficially hard-facing layer A ₄ and the hard-facing layer B _{3 as} the lowermost layer.
FIG. 6 is a partial sectional front view showing the whole vertical roll mill.
FIG. 7 is an example of a welding apparatus used for carrying out the present invention.
FIG. 8 is a front cross-sectional view of a main part showing a state before wear (A) and after wear (B) in the prior art.
FIG. 9 is a front cross-sectional view of a main part showing a state before wear (A) and after wear (B) in another conventional technique.
[Explanation of symbols]
1 table 2 rolls
11 Table facing line
12 Recess
21 Roll center lines A ₁ , A ₂ . . . Carbide overlay layer B ₁ , B ₂ . . . Hardened overlay layers a ₄₁ , a ₄₂ . . . Thin layer _b 31 carbide cladding layer A _{_2, b 32.} . . Clearance gap S ₃ crushing terminating in thin layer S ₁ milling space beginning of the gap S ₂ milling space closest point carbide overlay layer B ₃

Claims

In the method of recovering the crushed surface of consumables such as vertical roll mill tables and rollers that were worn out, to the original shape by overlay welding, it is best to use a high hardness filler material B on the unevenly worn surface. A hardfacing layer B ₁ having a locus substantially similar to the original grinding surface having a grinding efficiency of ₁ mm is formed, and a hardness of Hv; 300 or more higher than the high hardness is formed on the hardfacing layer B _1. the carbide cladding layer a ₁ more smaller form than the thickness of the hardfacing layer B ₁ with substantially similar trajectory to the trajectory, similarly hardfacing further ultra hard onto the cladding layer a ₁ the layers B _2, so as to form a carbide cladding layer a ₂ onto the cured overlay layer B _2, hereinafter the same procedure alternately hardfacing layer B Repeat the carbide cladding layer a Draw a trace that is almost similar to the original pulverized surface and superimpose it. The method of reproducing vertical roller mill of the consumable member, characterized in that the return to Jo.

According to claim 1, carbide cladding layer A _1, A _2,. . . The thickness of each of the cured hardfacing layers B ₁ , B ₂ ,. . . A method for regenerating a consumable member of a vertical roll mill, wherein the thickness is less than at least 2/3 of each layer thickness.

In any one of Claims 1 thru | or 2, in order to form the superhard build-up layer A, 20-40 weight% of tungsten carbide granular materials are put in this matrix fusion pool, welding and forming the wire which forms a matrix. A method for regenerating a consumable member of a vertical roll mill, characterized in that a composite structure is added and dispersed at a ratio of

In Claim 3, it replaces with tungsten carbide addition, and it is C: 4.5-6.0% and Cr: 20.0-30. A multi-component carbide precipitation hardening type containing 0%, containing one or more of Mo, Nb, V, B, remaining Fe and impurities, and having Hv: 900 or more is used. To regenerate the consumable member of the vertical roll mill.