JP2004174578A

JP2004174578A - Method and device for manufacturing inner-surface coated cylindrical body and inner-surface coated cylindrical body manufactured thereby

Info

Publication number: JP2004174578A
Application number: JP2002345332A
Authority: JP
Inventors: Yasuo Watanabe; 康男渡辺; Michio Tanabe; 道夫田辺; Yoshinobu Soji; 義信曽地; Kenji Yatabe; 憲志矢田部; Akihiro Takeya; 昭宏竹屋; Fumiaki Tada; 文明多田; Kazunori Nishibaba; 和典西馬場
Original assignee: Dai Ichi High Frequency Co Ltd
Current assignee: Dai Ichi High Frequency Co Ltd
Priority date: 2002-11-28
Filing date: 2002-11-28
Publication date: 2004-06-24
Anticipated expiration: 2022-11-28
Also published as: TWI259851B; CN1970835A; CN1504287A; HK1063757A1; TW200408728A; CN100563872C; CN100540741C; JP3774696B2

Abstract

PROBLEM TO BE SOLVED: To provide technology for forming an inner surface coating on the inner circumferential face of a cylindrical body with a self-fluxing alloy having a large surface hardness. SOLUTION: Inside the cylindrical body 1 placed sideways, there is arranged a self-fluxing alloy powder uniformly in the axial direction of the cylindrical body, in a quantity suitable for the thickness of coating to be formed. After a powder layer of a uniform thickness is formed on the inner circumferential face by rotating the cylindrical body 1 at high speed, the powder inside is melted by heating the cylindrical body 1 to form a molten metal layer, then cooled and solidified to form the inner surface coating. In melting and solidifying the self-fluxing alloy, with a centrifugal force of 20-50G kept working on the inner circumferential face position of the cylindrical body 1, the hard ceramics fine particles of low specific gravity in the molten metal are integrated anti-centrifugally on the inner diameter side, increasing the density and hardness of the hard fine particles on the face of the inner surface coating. COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は、樹脂成形機シリンダーやスラリー輸送用鋼管などの、金属製の筒体本体の内周面に、耐摩耗性、耐食性に優れた自溶合金被覆を施した内面被覆筒体の製造技術に関する。
【０００２】
【従来の技術】
【特許文献１】特開昭６４−２５９８９号公報
【特許文献２】特開平１−９６３６３号公報
従来より、鋼管等の金属製の筒体本体の内周面に自溶合金被覆を施した内面被覆筒体が知られている。この内面被覆筒体を製造する方法として、前記特許文献１（特開昭６４−２５９８９号公報）には、筒体本体（管）を、内周面における遠心力が３Ｇ以上になるように回転させた状態で自溶合金粉末を供給してその筒体本体内周面に一定厚さの粉末層を形成し、その後その筒体本体を、前記粉末層が焼結状態を呈する温度まで加熱して前記粉末層を筒体本体内周面に付着させてから回転を停止し、次いで、筒体本体をその内周面温度が前記粉末の溶融温度以上になるように加熱して筒体本体内周面に付着した粉末層を溶融させ、拡散を伴った形で母材に接合させることにより、内面被覆を形成する方法が記載されている。また、前記特許文献２（特開平１−９６３６３号公報）には、被覆形成厚さに見合った量の自溶合金粉末を筒体本体内に装入した後、その筒体本体を、内周面の遠心力が２Ｇ以上、外周面の遠心力が７Ｇ以下となるように回転させながら、筒体本体を前記粉末の溶融温度以上になるように加熱して筒体本体内周面に付着した粉末層を溶融させ、拡散を伴った形で母材に接合させることにより、内面被覆を形成する方法が記載されている。いずれの方法においても、筒体本体内周面に配した自溶合金粉末層を、加熱溶融し、拡散を伴った形で母材に溶着させることにより、母材に良好に接合した緻密な且つ無気孔に近い自溶合金の内面被覆を形成でき、特に、特許文献２に記載の方法では、筒体本体を回転させた状態で粉末層の溶融・凝固を行うという一種の遠心鋳造を行っており、筒体本体内周面に形成される溶湯層に遠心力を作用させることで一層気孔を少なくでき、形成された自溶合金の内面被覆は硬度が大きく、耐摩耗性、耐食性に優れたものであった。
【０００３】
【発明が解決しようとする課題】
最近、筒体本体に形成する内面被覆の耐摩耗性を一層向上させるため、内面被覆の硬度を更に向上させることが望まれてきた。硬度を上げるには、タングステンカーバイドなどの硬質の微粒子を導入した自溶合金を用いれば良いと思われるが、必ずしも満足すべき結果が得られないことが判明した。すなわち、特許文献１に記載の方法では、タングステンカーバイドなどの硬質の微粒子を導入することで、或る程度の硬度の向上は確保できるものの、特許文献２に記載の方法に比べて残存する気孔量が多いという欠点を有しており、一方、特許文献２に記載の方法では、タングステンカーバイドなどの硬質の微粒子を導入しても、内面被覆表面の硬度の向上はほとんど見られなかった。これは、多用されてきたタングステンカーバイドの微粒子の比重（≒１５）が目地金属相の比重（８〜９）より大幅に大であるために、内面被覆の表面（内周面）から離れる方向に移動し、表面にはあまり存在しなくなるためと考えられる。しかも、この硬質の微粒子が内面被覆の外径側に、即ち母材（筒体本体）との境界領域に集まり、母材に対する内面被覆の拡散を伴った接合を阻害し、接着力を低下させるという新たな問題も生じた。
【０００４】
本発明は上記事情に鑑みてなされたものであって、遠心鋳造によって筒体本体内周面に形成する自溶合金の内面被覆の、少なくとも表面の硬度を大幅に向上させる技術の提供を課題としたものである。
【０００５】
【課題を解決するための手段】
上記課題を解決すべくなされた本願の請求項１に係る発明は、円筒状内周面を有する筒体本体の前記内周面に自溶合金を遠心鋳造して被覆する工程を含んだ内面被覆筒体の製造方法において、前記遠心鋳造を、前記内周面位置に２０〜５０Ｇの遠心力が生じる回転速度で行うことにより、鋳造中の自溶合金溶湯中に存在する硬質セラミックス微粒子のうちの、溶湯の目地金属相より低比重の微粒子を遠心鋳造系の内径側に反遠心集積させ、この状態で溶湯を凝固させることで、前記低比重の微粒子が内径側に集積した内面被覆を得ることを特徴とするものである。このように低比重の微粒子が内径側に集積した内面被覆を形成したことで、その内面被覆の表面の硬度がきわめて大きくなっており、耐摩耗性に優れた内面被覆筒体を製造できる。また、硬質セラミックス微粒子を内面被覆の内径側に反遠心集積できる結果、外径側では硬質セラミックス微粒子の濃度が低くなり、靱性を高めることができると共に母材に対する拡散を伴った接合を阻害する因子が少なくなって母材に対する接合力を高めることができ、耐衝撃性、耐剥離性にも優れた内面被覆筒体を製造できる。
【０００６】
請求項２に係る発明は、請求項１記載の発明において、前記内面被覆の内径側に集積する前記目地金属相より低比重の微粒子を、自溶合金溶湯から析出したクロム系のホウ化物，炭化物，ホウ炭化物のいずれかに属するセラミックスの微粒子としたものである。これにより、自溶合金として、ニッケル自溶合金、コバルト自溶合金などの、汎用されている自溶合金をそのまま使用しながら、内面被覆の表面硬度を高めることができる。
【０００７】
請求項３に係る発明は、請求項１記載の発明において、前記内面被覆の内径側に集積する前記目地金属相より低比重の微粒子を、自溶合金溶湯から析出したクロム系のホウ化物，炭化物，ホウ炭化物のいずれかに属するセラミックスの微粒子と、前記自溶合金溶湯中に、当該自溶合金の基本組成外の成分として導入された、前記クロム系のセラミックスの比重を越えない比重の硬質セラミックスの微粒子としたものである。これにより、内径側に集積する硬質の微粒子量を多くすることができ、表面硬度を一層高めることができる。
【０００８】
請求項４に係る発明は、円筒状内周面を有する筒体本体の前記内周面に自溶合金を遠心鋳造して被覆する工程を含む内面被覆筒体の製造方法において、前記遠心鋳造を、溶湯層の表面に０．３〜３ＭＰａの気圧を作用させた状態で行うことを特徴とする内面被覆筒体の製造方法である。遠心鋳造を利用して自溶合金の内面被覆を形成すると、被覆内に残存する気孔はきわめて微量となるが、更に、その遠心鋳造過程において、溶湯層の表面に０．３〜３ＭＰａの気圧を作用させ、その状態で凝固させることにより、溶湯層の中に微量に残存する気孔が気圧により圧縮されて体積が減少し、得られた内面被覆内の残存気孔が体積割合において一層微量となる。このため、得られた内面被覆は気孔の占積による硬度の減殺が抑えられる結果、気圧を加えないで遠心鋳造した場合に比べて硬度が大きくなっており、この方法によっても耐摩耗性に優れた内面被覆筒体を製造できる。
【０００９】
請求項５に係る発明は、円筒状内周面を有する筒体本体の前記内周面に自溶合金を遠心鋳造して被覆する工程を含む内面被覆筒体の製造方法において、前記遠心鋳造を、溶湯層の表面に０．３〜３ＭＰａの気圧を作用させた状態で行うと共に、前記溶湯層の表面に前記気圧を作用させた状態においては、前記筒体本体の回転速度を、前記内周面位置に１０Ｇ以上の遠心力が生じる回転速度としたものである。溶湯層の表面に０．３〜３ＭＰａの気圧を作用させた状態で凝固させると、前記したように、溶湯層内の気孔を圧縮して体積を減少させる作用が生じるが、場合によっては加圧気体が溶湯層内の気孔に貫通することがあり、更には溶湯層と筒体本体の界面にまで貫通することもあり、この状態で凝固が行われると、内面被覆に残存気孔よりもかなり大きい、且つ表面に通じる孔即ちピンホールが生じてしまう。この現象を防止するため、この発明では、前記筒体本体の回転速度を、前記内周面位置に１０Ｇ以上の遠心力が生じる回転速度とし、溶湯層に大きい遠心力を作用させることで、溶湯層内に厚さ方向を含む全領域に亘って均等に圧縮応力が生じて、加圧気体の圧入口となるような受圧挙動のばらつきが希釈された状態で気圧を作用させて、加圧気体の貫通を防止する。これにより、ピンホールのほとんどない内面被覆を形成できる。
【００１０】
請求項６に係る発明は、円筒状内周面を有する筒体本体の前記内周面に自溶合金を遠心鋳造して被覆する工程を含む内面被覆筒体の製造方法において、前記遠心鋳造を、溶湯層の表面に０．３〜３ＭＰａの気圧を作用させた状態で行うと共に、前記溶湯層の表面に前記気圧を作用させた状態においては、前記筒体本体の回転速度を、前記内周面位置に２０〜５０Ｇの遠心力が生じる回転速度とすることにより、鋳造中の自溶合金溶湯中に存在する硬質セラミックス微粒子のうちの、溶湯の目地金属相より低比重の微粒子を遠心鋳造系の内径側に反遠心集積させ、この状態で溶湯を凝固させることで、前記低比重の微粒子が内径側に集積した内面被覆を得ることを特徴とするものである。すなわち、この発明は、請求項１の発明と請求項４の発明の特徴を合わせたものであり、２０〜５０Ｇの遠心力付加によって、内面被覆の内径側に硬質の微粒子を集積して表面の硬度を上げることができると共に、０．３〜３ＭＰａの気圧を作用させることで内面被覆内の残存気孔をきわめて微量として硬度を上げることができ、一層硬度の高い内面被覆を備えた内面被覆筒体を製造することができる。
【００１１】
請求項７の発明は、請求項１から６の発明において、前記遠心鋳造における前記自溶合金溶湯の到達する温度を、当該自溶合金の溶融・凝固に係る固相線から液相線温度に至る固液共存温度内の、固相線側から７０％に位置する温度以下としたものである。自溶合金の遠心鋳造を行うには、自溶合金の溶湯層を被鋳造面に形成することが必要であるが、この際の溶湯温度が高くなると、硬度向上に寄与する金属ホウ化物や金属ケイ化物などの微粒子が溶体化したり酸化による消耗を生じて硬さが減少し、更には酸化物が混入する恐れが生じる。そこで、溶湯温度を前記のように設定することで、硬質の微粒子の溶体化や酸化消耗による減少あるいは酸化物混入を防止し、硬度の高い被覆を形成できる。
【００１２】
請求項８に係る発明は、請求項１から６の発明において、前記遠心鋳造における、前記内周面上への自溶合金溶湯層の形成を、前記筒体本体内に自溶合金の粉末を導入し、この粉末を前記筒体本体回転下で加熱溶融させて行うようにしたものである。筒体本体の内周面上への自溶合金溶湯層の形成は、筒体本体の外部で溶湯を作成し、その溶湯を筒体本体内に供給する方法で行っても良いが、この発明のように、自溶合金を粉末形態で筒体本体内に供給し、その位置で加熱溶融させる構成とすると、自溶合金の取り扱いが容易となり且つ必要な設備も簡略化できる。
【００１３】
請求項９に記載の発明は、請求項１から６の発明において、前記遠心鋳造における、前記内周面上への自溶合金溶湯層の形成を、（１）横置きした筒体本体の内部に、被覆形成厚さに見合った量の自溶合金の粉末を筒体軸線方向均等に配置し、（２）筒体本体をその軸線を中心に回転させ、前記筒体本体の内周面位置に３Ｇ以上の遠心力が生じる回転速度に到達させることで、筒体本体内の粉末を、筒体本体周方向にも行き亘らせた形で筒体本体内面に張りつかせ、その際、３Ｇ以上の遠心力が生じる回転速度に到達する時間を、筒体軸線方向均等に配置した粉末の筒体軸線方向の移動を抑制するように、次の実験式（Ａ）
τ（秒）＝３×１０^５／Ｄ^３・・・（Ａ）
〔Ｄは筒体の内直径（ｍｍ）〕
で求められる時間τを超えない値とすることで、筒体軸線方向及び周方向に厚さ偏倚のほとんどない粉末層を形成して筒体本体内面に張りつかせ、（３）筒体本体の回転を続けたままで、筒体本体全体を同時昇温させるように筒体本体を加熱して筒体本体内の粉末を同時溶融させることによって行うように構成したものである。粉末供給に際し、前記した（１），（２）の工程を採用したことで、筒体本体内周面に、筒体軸線方向に厚さ偏倚のきわめて小さい自溶合金粉末層を形成することができ、その粉末層を加熱溶融・凝固させることで厚さ偏倚のきわめて小さい自溶合金の内面被覆を形成できる。
【００１４】
請求項１０に係る発明は、請求項１から６の発明において、前記遠心鋳造における、前記内周面上への自溶合金溶湯層の形成を、前記筒体本体内に自溶合金の粉末を導入し、この粉末を前記筒体本体回転下で加熱溶融させて行うようにすると共に、前記筒体本体内の粉末の溶融を減圧下で行う構成としたものである。この構成により、粉末の溶融により形成される溶湯層内からの気泡除去を効果的に行うことができると共に溶湯層の酸化を防止でき、残存気孔のきわめて少ない且つ硬度の向上に寄与する析出微粒子の酸化消耗減少及び酸化物の混入の少ない内面被覆を形成できる。
【００１５】
請求項１１に係る発明は、円筒状内周面を有する筒体本体の前記内周面に自溶合金の内面被覆を形成した内面被覆筒体であって、前記内面被覆内の内径側に、クロム分濃度が２０〜４０ｍａｓｓ％に及ぶレベルにまでクロム化合物系硬質セラミックスの微粒子を高密度に分布させることで硬度を高めた硬質層を形成したことを特徴とする内面被覆筒体である。この内面被覆筒体は、内面被覆の表面（内周面）に硬度を高めた硬質層を備えているので、優れた耐摩耗性を有している。
【００１６】
請求項１２に係る発明は、請求項１１の発明において、前記内面被覆内の外径側に、非金属介在物の検鏡面積率が０．１％以下の清浄層を形成したものである。この清浄層は非金属介在物が少ないため優れた靱性を備えており、且つ母材に対する拡散を伴った接合を阻害する非金属介在物が少ないので母材に対する接合強度を大きくでき、このため、内面被覆は、表面の硬質層を靱性に優れ且つ母材に強固に接合された清浄層で支持した構造となり、耐摩耗性に優れるのみならず、耐衝撃性、耐剥離性等もに優れている。
【００１７】
請求項１３に係る発明は、筒体本体を水平に支持し且つ回転させる筒体支持回転装置と、該筒体支持回転装置で支持された筒体本体内に被覆形成厚さに見合った量の自溶合金の粉末を供給する粉末供給装置と、前記筒体回転支持装置に支持された筒体本体の全長を加熱する加熱装置を備え、前記筒体支持回転装置が、前記筒体本体を、筒体本体内周面位置に２０〜５０Ｇの遠心力が生じる回転速度で回転させ得る構成とした、内面被覆筒体の製造装置である。この構成の製造装置では、筒体支持回転装置で支持された筒体本体内に被覆形成厚さに見合った量の自溶合金の粉末を供給し、筒体本体を回転させて内周面に自溶合金の粉末層を形成した後、その粉末層を加熱溶融して溶湯層を形成し、次いで凝固させるという遠心鋳造を行うことができ、しかも、その遠心鋳造を、前記内周面位置に２０〜５０Ｇの遠心力が生じる回転速度で行うことができる。このため、鋳造中の自溶合金溶湯中に存在する硬質セラミックス微粒子のうちの、溶湯の目地金属相より低比重の微粒子を遠心鋳造系の内径側に反遠心集積させ、この状態で溶湯を凝固させることで、前記低比重の微粒子が内径側に集積した内面被覆を得ることができ、表面硬度のきわめて大きい内面被覆を備え、耐摩耗性に優れた内面被覆筒体を製造できる。
【００１８】
請求項１４に係る発明は、筒体本体を水平に支持し且つ回転させる筒体支持回転装置と、該筒体支持回転装置で支持された筒体本体内に被覆形成厚さに見合った量の自溶合金の粉末を供給する粉末供給装置と、前記筒体回転支持装置に支持された筒体本体の全長を加熱する加熱装置と、前記筒体本体の内表面に０．３〜３ＭＰａの気圧を作用させる加圧手段とを有する、内面被覆筒体の製造装置である。この構成の製造装置では、筒体支持回転装置で支持された筒体本体内に被覆形成厚さに見合った量の自溶合金の粉末を供給し、筒体本体を回転させて内周面に自溶合金の粉末層を形成した後、その粉末層を加熱溶融して溶湯層を形成し、次いで凝固させるという遠心鋳造を行うことができ、しかも、その遠心鋳造における、前記内周面上への自溶合金溶湯層の形成から、この溶湯層を凝固させるまでの過程を、前記溶湯層の表面に０．３〜３ＭＰａの気圧を作用させた状態で経過させることができ、残存気孔の極めて少ない、硬度の大きい内面被覆を備え、耐摩耗性に優れた内面被覆筒体を製造できる。
【００１９】
請求項１５に係る発明は、筒体本体を水平に支持し且つ回転させる筒体支持回転装置と、該筒体支持回転装置で支持された筒体本体内に被覆形成厚さに見合った量の自溶合金の粉末を供給する粉末供給装置と、前記筒体回転支持装置に支持された筒体本体の全長を加熱する加熱装置と、前記筒体本体の内表面に０．３〜３ＭＰａの気圧を作用させる加圧手段とを有し、前記筒体支持回転装置を、前記筒体本体を、筒体本体内周面位置に１０Ｇ以上の遠心力が生じる回転速度で回転させ得る構成とした、内面被覆筒体の製造装置である。この構成の製造装置では、筒体本体内の溶湯層の表面に０．３〜３ＭＰａの気圧を作用させた状態で遠心鋳造を行うことができると共にその際に、筒体本体を、筒体本体内周面位置に１０Ｇ以上の遠心力が生じる回転速度で回転させておくことができ、加圧気体が溶湯層内の気孔に貫通するとか溶湯層と筒体本体の界面に貫通することを防止して、ピンホールのほとんどない内面被覆を形成できる。
【００２０】
請求項１６に係る発明は、筒体本体を水平に支持し且つ回転させる筒体支持回転装置と、該筒体支持回転装置で支持された筒体本体内に被覆形成厚さに見合った量の自溶合金の粉末を供給する粉末供給装置と、前記筒体回転支持装置に支持された筒体本体の全長を加熱する加熱装置と、前記筒体本体の内表面に０．３〜３ＭＰａの気圧を作用させる加圧手段とを有し、前記筒体支持回転装置を、前記筒体本体を、筒体本体内周面位置に２０〜５０Ｇの遠心力が生じる回転速度で回転させ得る構成とした、内面被覆筒体の製造装置である。この構成の製造装置では、筒体本体内の溶湯層の表面に０．３〜３ＭＰａの気圧を作用させた状態で遠心鋳造を行うことができると共にその際に、筒体本体を、筒体本体内周面位置に２０〜５０Ｇの遠心力が生じる回転速度で回転させておくことができ、０．３〜３ＭＰａの気圧を作用させることで内面被覆内の残存気孔をきわめて微量として硬度を上げることができるのみならず、２０〜５０Ｇの遠心力付加によって、内面被覆の内径側に硬質の微粒子を反遠心集積して表面の硬度を上げることができ、一層硬度の高い内面被覆を備えた内面被覆筒体を製造することができる。
【００２１】
請求項１７に係る発明は、請求項１４から１６の発明において、前記加熱装置を、前記筒体回転支持装置に支持された筒体の円周方向の小区間を筒体全長に亘って同時に誘導加熱する誘導子を備えた構成としたものである。この構成により、筒体本体全長を同時に且つ敏速に加熱することができ、自溶合金粉末層の加熱溶融を敏速に行うことができる。
【００２２】
【発明の実施の形態】
以下、本発明の実施形態を図面を参照して説明する。図１（ａ），（ｂ）は本発明の実施形態に係る内面被覆筒体の製造装置を、異なる作動状態で示す概略斜視図、図２（ａ），（ｂ），（ｃ），（ｄ）は図１の製造装置によって筒体本体の内周面に自溶合金の内面被覆を形成する手順を示す概略断面図であり、１は円筒状内周面を備えた筒体本体である。筒体本体１は、金属製のものであれば任意であり、代表的な例としては、樹脂成形機シリンダーなどのシリンダーやスラリー輸送用鋼管等の各種鋼管を挙げることができる。２は筒体本体１の内周面に内面被覆を形成するための自溶合金の粉末である。被覆を形成する自溶合金としては、汎用のニッケル自溶合金（例えば、ＪＩＳ，８３０３のＳＦＮｉ４など）、汎用のコバルト自溶合金（例えば、ＪＩＳ，８３０３のＳＦＣｏ３など）等を例示できる。また、必要に応じ、これらの自溶合金に、自溶合金溶湯から析出したクロム系のホウ化物，炭化物，ホウ炭化物のいずれかに属するセラミックスの比重と同程度或いはそれ以下の比重の、具体的には、７以下の比重の硬質セラミックス（例えば、ＢＮ：比重２．３４，Ｂ_４Ｃ：比重２．４７，Ｓｉ_３Ｎ_４：比重３．２，ＳｉＣ：比重３．２１，Ｖ_２Ｏ_５：比重３．３６，ＶＯ_２：比重４．３４，ＴｉＢ_２：比重４．５，Ｖ_２Ｏ_３：比重４．８７，ＴｉＣ：比重４．９４，ＴｉＢ：比重５．０９，ＴｉＮ：比重５．４３，ＶＯ：比重５．７６，ＶＣ：比重５．７７，ＺｒＢ_２：比重６．０８，ＺｒＣ：比重６．７３，ＮｂＢ_２：比重６．９７，あるいは、これらの複合物など）の微粒子を導入したものを用いることもできる。
【００２３】
３は、筒体本体１を水平に支持し且つ回転させる筒体支持回転装置であり、この実施形態では、筒体本体１の下側を支持する２本の受けロール４と筒体本体１の上側を押さえる押えロール５（図１では図示を省略）と、前記２本の受けロール４を回転駆動する可変速モータ６と、その可変速モータ６による受けロール４の回転速度及び加速度を制御する制御装置７等を備えている。この可変速モータ６及びその制御装置７は、筒体本体１を、筒体本体１の内周面位置に２０〜５０Ｇの遠心力が作用する回転速度で回転させることができ、また、上記した実験式（Ａ）で求められる時間τを超えない短時間内に３Ｇ以上の遠心力が生じる回転速度に到達させるように加速することの可能な構成としている。９は、筒体支持回転装置３で支持された筒体本体１内に被覆形成厚さに見合った量の自溶合金の粉末を供給する粉末供給装置であり、この実施形態では、先端から粉末を送り出す粉末供給管１０と、その粉末供給管１０を保持して管軸方向に移動可能なホッパー台車１１等を備えている。１３は、筒体支持回転装置３に支持された筒体本体１の全長を加熱する加熱装置であり、この実施形態では、筒体本体１の円周方向の小区間を筒体本体全長に亘って誘導加熱する面焼形コイルである誘導子が用いられている。
【００２４】
次に、上記構成の内面被覆筒体の製造装置を用いた内面被覆筒体の製造方法を説明する。まず金属製の筒体本体１を用意し、その内周面を被覆に適した表面粗さに調える。ここで、筒体本体１内周面の表面粗さは、限定するものではないが、５〜２０μｍＲａ程度に選定しておくことが好ましい。この範囲の表面粗さは、内周面を清浄にする操作を兼ねた内面ブラストによって容易に形成できる。筒体本体内周面の表面粗さを５〜２０μｍＲａに調えておくと、筒体本体１内に自溶合金粉末を供給し軸線方向に均等に配置した後、筒体本体１を高速回転させて周方向に均等に分布させる際の加速途中において、粉末が筒体軸線方向に移動して厚さ偏倚を生じるという現象を抑制できる利点が得られる。この理由は、筒体本体１の内周面に適度な凹凸が存在し、それに粉末が引っかかることによって粉末の筒体軸線方向の移動が抑制されるためと思われる。筒体本体内周面の表面粗さは、大きいほど粉末の筒体軸線方向移動を抑制する効果が増す傾向があり、その抑制効果を利用するため、上記したように表面粗さを５μｍＲａ以上とするが、これが２０μｍＲａ以上となると粉末の移動抑制効果の増加がほとんど期待できなくなる。一方、粗面加工のコストはアップする。これらを考慮して表面粗さの上限を２０μｍＲａとすることが好ましい。
【００２５】
次に、筒体本体１を筒体支持回転装置３にセットして横置き状態とし、その横置きした筒体本体１の内部に、被覆形成厚さに見合った量の自溶合金の粉末２を筒体軸線方向均等に配置する操作を行う。具体的には、粉末供給装置９の粉末供給管１０を筒体本体１内に差し込み、所定量の自溶合金粉末２を筒体本体１内の軸線方向の適当な個所（１個所でも複数個所でもよい）に装入し［図２（ａ）参照］、粉末供給管１０を引き抜き、筒体本体１の両端を適当なカバー１５で閉じ、次いで、筒体本体１を、その筒体本体１内の粉末が筒体本体の周方向には行き亘らない程度の緩速で回転させる。この回転により、筒体本体１内に装入された粉末２を筒体本体の軸線方向に均等に行き亘らせて、軸線方向均等に配置することができる［図２（ｂ）参照］。この方法は、粉末供給管１０によって筒体本体１へ自溶合金粉末を装入するの際に粉末を筒体軸線方向に均等に装入しなくてもよいので、粉末装入作業を容易とできる利点が得られる。
【００２６】
なお、筒体本体１の内部に、被覆形成厚さに見合った量の自溶合金の粉末を筒体軸線方向均等に配置する操作は、上記した方法に限らず他の方法を採ることも可能である。例えば、粉末供給管１０を筒体本体１内に挿入し、その先端から一定流量で粉末を吐出しながらホッパー台車１１を筒体軸線方向に一定速度で移動させる方法を採ることによって、筒体本体１内に粉末を軸線方向均等に配置することができる。また、筒体本体１内に装入する粉末供給管１０として、その側面に軸線方向に延びるスリット状の吐出口或いは軸線方向に並んだ多数の孔からなる吐出口を形成したものを用い、その吐出口を閉じるか上向きにした状態で粉末供給管１０内に軸線方向に均等に自溶合金粉末を入れ、その粉末供給管１０を筒体本体１内に挿入し、その後吐出口を開くか下向きにして粉末供給管１０内の自溶合金粉末を筒体本体１内に供給する方法を採ることによっても、筒体軸線方向均等に配置することができる。
【００２７】
筒体本体１内に自溶合金粉末２を筒体軸線方向均等に配置した後は、筒体支持回転装置３によって、筒体本体１をその軸線を中心に回転させ、筒体本体１の内周面位置に２０〜５０Ｇの遠心力が生じる回転速度に到達させる。この回転により、筒体本体１内に装入されていた自溶合金粉末２が筒体本体周方向に均等に行き亘り、筒体本体内周面に張りつく［図２（ｃ）参照］。このようにして筒体本体周方向に均等に行き亘り、筒体本体内周面に張りついた粉末２は、内周面位置に３Ｇ以上の遠心力が生じる回転速度以上では、筒体本体内内周面上でほとんど移動せず、その位置に保持され、従って、筒体本体内周面に均一な肉厚の粉末層が形成され、維持される。ところが、筒体本体１の加速中において、内周面位置に１Ｇ〜２Ｇ程度の遠心力が生じる回転速度においては、粉末は筒体本体内周面に一応張りつくが、遠心力に基づく拘束力が小さいため、筒体本体１内周面の肌目等の微視的な方向性によって粉末には右ねじ的または左ねじ的らせん変位が生じ、粉末が筒体軸線方向に移動して、筒体軸線方向の厚さ偏倚が生じる傾向がある。そこで、筒体本体１の回転を開始して所定の回転速度への加速に当たっては、このような筒体軸線方向の厚さ偏倚がほとんど生じないように（生じても、許容範囲内に納まるように）、短時間で筒体本体の内周面位置に３Ｇ以上の遠心力が生じる回転速度に到達するように加速する。具体的には、内周面の表面粗さを５〜２０μｍＲａに調えた筒体本体１に対して、その筒体本体１の回転速度を次の実験式（Ａ）
τ（秒）＝３×１０^５／Ｄ^３・・・（Ａ）
で求められる時間τを超えない短時間内に前記３Ｇ以上の遠心力が生じる回転速度に到達させるように、筒体本体１の加速を行う。これにより、筒体本体１内周面に、筒体軸線方向に厚さ偏倚のきわめて小さい自溶合金粉末層を形成し張りつかせることができる。なお、この実験式（Ａ）の根拠については、後述する。
【００２８】
筒体本体１を内周面位置に２０〜５０Ｇの遠心力が生じる所定の回転速度に到達させた後は、筒体本体１をその回転速度に保持し、回転を続けたままで、加熱装置１３によって筒体本体１を加熱して筒体本体内の粉末２を溶融させたのち、溶融状態に保持する。これにより、筒体本体１の内周面上に自溶合金の溶湯層が形成される。ここで、溶湯層内における溶融状態とは、必ずしも粉末全体が完全に溶融した状態のみを意味するものではなく、粉末の少なくとも一部が溶融して粉末同志で及び筒体本体内周面に対して融着しうる状態を意味する。従って、加熱装置１３による筒体本体１の加熱温度は、筒体本体内周面に張りついている自溶合金粉末が少なくとも部分的に溶融して粉末同志で及び筒体本体内周面に対して融着しうるように選定すればよく、具体的には、自溶合金に係る状態図における固相線の温度を超えた温度とすればよい。
【００２９】
一方、筒体本体１の加熱温度は高くするほど、粉末の溶融割合が多くなり、ついには完全に溶融した状態となる。そして、粉末層を完全に溶融した状態とすることで、より緻密な且つ気孔やピンホールのない融着被覆層を形成することができると考えられていたが、本発明者等が確認したところ、必ずしも粉末を完全に溶融させなくても、緻密な且つ気孔やピンホールのない融着被覆層を形成することができることが判明した。また、粉末層を完全に溶融した状態とすると、溶融層の流動性によって被覆厚さを筒体軸線方向に均等とすることができ、従って筒体本体内周面に張り付けた粉末層に厚さ偏倚があっても、それを修正することができるが、上記したように粉末層を形成した時点で厚さ偏倚がほとんど無い状態としておけば、完全溶融状態として厚さ偏倚を修正する必要はない。一方、粉末層を完全溶融しようとすると、筒体本体１の加熱温度を高くしなければならず、当然、熱エネルギー消費が大きくなり、且つ加熱時間も長くなってしまう。しかも、自溶合金の液相線の温度を超えた完全溶融状態とすると、自溶合金内の硬度向上に寄与する金属ホウ化物や金属ケイ化物などの粒子が溶体化したり酸化消耗によって減少し、硬さが低下するとか、酸化物が混入するという欠点も生じる。これらのことを考慮すると、筒体本体１の加熱温度の上限は、筒体本体内の自溶合金の温度が該自溶合金の溶融に係る液相線の温度を超えないように選定することが好ましく、更には、自溶合金溶湯の到達する温度を、当該自溶合金の溶融・凝固に係る固相線から液相線温度に至る固液共存温度内の、固相線側から７０％に位置する温度以下とすることが好ましい。
【００３０】
自溶合金粉末層を加熱溶融する際の筒体本体１の回転速度は、前記したように２０〜５０Ｇの遠心力が作用する回転速度とする。従来より、筒体本体内面に形成した自溶合金粉末層を溶融して緻密化する際、筒体本体１を回転させて遠心力を作用させることにより、自溶合金の溶湯層からの気泡除去効果が増すことが知られており、上記した特許文献２に記載の方法でも、２Ｇ以上の遠心力が作用する状態で溶融処理している。しかしながら、遠心力による気泡除去効果は、遠心力が７〜８Ｇ程度に増加するまでは、遠心力の増加と共に向上するが、それ以上に遠心力が増加しても気泡除去効果はさほど向上せず、このため、従来は、せいぜい遠心力を１０Ｇ程度以下としていた。これに対し、この実施形態では、２０〜５０Ｇの遠心力を採用している。このような高Ｇの遠心力を用いたことにより、気泡除去効果のみならず、溶湯中に存在する目地金属相より低比重の硬質セラミックス微粒子の内径側への反遠心集積効果が得られ、これにより表面層の硬度を大幅に向上させることができる。すなわち、自溶合金の溶湯中における目地金属は、Ｎｉ（比重８．９），Ｃｒ（比重８．５），Ｃｏ（比重８．８５）などであるが、溶湯中には、自溶合金溶湯から析出したクロム系のホウ化物（ＣｒＢ：比重６．２），炭化物（Ｃｒ_３Ｃ_２：比重６．６８，Ｃｒ_７Ｃ_３：比重６．９２など）、あるいは、これらが複合した組成のホウ炭化物（比重６〜７程度）などの比重が６〜７の範囲にある硬質セラミックス微粒子が存在している。これらの硬質セラミックス微粒子は、目地金属相に比べて低比重ではあるが、その差がさほど大きくないため、従来行っていた３〜８Ｇ程度の遠心力では、溶湯層の内径側に反遠心集積することがほとんどできなかったが、２０〜５０Ｇといった高Ｇ遠心力を用いることで、内径側に反遠心集積することができた。
【００３１】
筒体本体１内周面の自溶合金粉末を溶融状態に保持する時間は、１０〜１８０秒の範囲内に設定することが好ましい。この時間が１０秒未満では、溶湯の母材に対する拡散を伴った接合が不十分となるか或いは低比重の硬質セラミックス微粒子の内径側への集積が不十分となり、一方、１８０秒を超えると、溶湯中の硬質セラミックス微粒子の溶体化や酸化消耗による減少が生じて、硬度を上げることができなくなるとか酸化物が混入する恐れが生じる。これらのことにより、筒体本体１を加熱して筒体本体内の粉末２を溶融させ、溶融状態に保持するに当たっては、筒体本体１の加熱を、内部の自溶合金粉末の温度が該自溶合金の溶融に係る固相線の温度は超えるが、液相線の温度は超えないように行うとともに、前記溶融状態に保持する時間を１０〜１８０秒に選定することが好ましい。
【００３２】
自溶合金粉末を所定時間、溶融状態に保持した後は、筒体本体１の回転を続けたままで冷却段階に移行させて筒体本体１内の溶融自溶合金を凝固させる。この冷却は、炉内冷却や保温冷却、あるいは放冷、空冷等、任意の冷却方法を採用しうるが、冷却が速すぎると凝固した自溶合金被覆が熱応力によって割れることとなる。よって、割れを生じない程度のなるべる短時間の冷却スケジュールを実験的に求めることが望ましい。
【００３３】
以上のようにして、自溶合金を筒体本体内周面全体に一度に融着させて自溶合金被覆を形成することができ、その後、筒体本体１を装置から取り外すことで、図２（ｄ）に示すように、筒体本体１の内周面に自溶合金の内面被覆２１を有する内面被覆筒体２０を製造できる。得られた自溶合金の内面被覆２１は、表面（内周面）の硬度がきわめて高くなっており、また、筒体軸線方向及び円周方向に厚さ偏倚がきわめて小さくなっている。
【００３４】
以上の工程によって得られた内面被覆筒体２０の内面被覆２１の断面を顕微鏡で観察したところ、図３に概略的に示すように、内面被覆２１は、表面層２１ａ，中間層２１ｂ，境界層２１ｃからなる層構造となっていた。表面層２１ａは、白いタスキ状組織部分と黒いタスキ状組織部分が混在した組織となっており、各タスキ状組織部分は目地金属（マトリックス金属）内に微粒子状の析出物が多く、細かく分布した組織となっていた。この表面層２１ａは後述する実施例１〜４に示すようにきわめて高い硬度（例えば、８１８〜９２７Ｈｖ）を示していた。微粒子状の析出物は、板状のもの、塊状のもの、しみ状のもの等が見られるが、それらの化学成分を測定したところ、金属成分は大部分がクロムであった。従って、この表面層２１ａは、クロム系のホウ化物，炭化物，ホウ炭化物などのクロム化合物系硬質セラミックスの微粒子を高密度に分布させることで硬度を高めた硬質層となっており、これにより高い硬度を示していると思われる。中間層２１ｂはマトリックス金属内に微粒子状の析出物が少量分散した組織となっており、表面層よりは硬度が低くなっていた。境界層２１ｃはマトリックス金属内に層状に共晶析出物が極く少量分散した組織となっており、更に硬度が低くなっていた。これは、高Ｇでの遠心鋳造を行った結果、マトリックス金属内に含まれる硬質セラミックス微粒子などの非金属介在物が内径側に移動し、境界層２１ｃはほとんどがマトリックス金属による清浄層となっていたためと思われる。この境界層２１ｃは、非金属介在物がほとんどない清浄層であるので、靱性に優れており、中間層２１ｂの介在によってもたらされる傾斜組成構造と相まって硬質の表面層２１ａを良好に支持すると共に、母材（筒体本体１）に対して良好に拡散を伴った接合をしている。このように、内面被覆２１は表面（内周面）の硬度がきわめて高いにも係わらず、適度な靱性を備え且つ母材に対する良好な接着性を有するという特性を備えており、耐摩耗性、耐衝撃性、耐剥離性等に優れている。
【００３５】
前記した内面被覆２１の表面層２１ａはクロム分濃度が高いほど硬度が高く、耐摩耗性に優れることとなるが、硬度をあまり高くすると製造が困難となる。そこで、表面層２１ａのクロム分濃度は２０〜４０ｍａｓｓ％程度とすることが好ましい。境界層２１ａは、非金属介在物が少ないほど、靱性が増し、且つ母材に対する拡散を伴った接合特性が良好となるので好ましく、具体的には、非金属介在物の検鏡面積率を０．１％以下とすることが好ましい。
【００３６】
上記の実施形態において、回転中の筒体本体１を加熱して内部の自溶合金粉末を溶融させる際には、筒体本体内に空気が入った状態となっているが、本発明はこの構成に限らず、筒体本体内を減圧した状態で行って被覆内気孔を極小化し又は無酸化雰囲気にした状態で行って自溶合金酸化の極小化を図ってもよい。図４は筒体本体内を減圧した状態で自溶合金粉末の加熱溶融操作を行うために使用する製造装置の１例を示すものである。この製造装置では、筒体本体１の一端に取り付けるカバー１５Ａに連結管２５を連結しており、その連結管２５に回転継手２６を介して配管２７を接続し、その配管２７に開閉弁２８及び真空ポンプ２９を接続している。その他の構造は、図１に示す製造装置と同様である。図４の製造装置を用いる場合には、図２（ａ）に示すように筒体本体１内に自溶合金の粉末２を供給した後、図４に示すように筒体本体１の両端にカバー１５，１５Ａを取り付けて、筒体本体１の両端を閉じると共に内部を真空ポンプ２９に連通させ、真空ポンプ２９を作動させて筒体本体１内を減圧した状態で、上記した実施形態と同様に筒体本体１を回転させ、筒体本体１の内周面位置に２０〜５０Ｇの遠心力を作用させ、その状態で自溶合金粉末の加熱溶融・凝固を行う。これにより、きわめて硬度の高い表面層を持った内面被覆を形成できる。また、加熱溶融時に筒体本体１内を減圧しているので、溶湯内の気泡の除去効果が大きく、残存気孔のきわめて小さい内面被覆を形成できる。なお、真空ポンプ２９に代えて、不活性ガスの供給装置を接続することで、筒体本体１内に不活性ガスを満たして無酸化雰囲気とすることができ、その状態で自溶合金粉末の加熱溶融・凝固を行うことで、自溶合金の酸化を極小化を図ることができる。以上に説明した各実施形態では、筒体本体１の内周面上に自溶合金粉末層を形成した時点で、すでに筒体本体の内周面位置に２０〜５０Ｇの遠心力を作用させているが、本発明はこの場合に限らず、自溶合金粉末層の形成時には、筒体本体１を内周面位置に３Ｇ以上の適当な遠心力が作用する回転速度とし、その状態で粉末層を加熱溶融して溶湯層を形成した後、筒体本体１の回転速度を増して２０〜５０Ｇの遠心力を作用させ、その状態で凝固させるようにしてもよい。
【００３７】
図５は本発明の他の実施形態に係る内面被覆筒体の製造装置を示すものである。この実施形態の製造装置は、図４に示す実施形態と同様に、筒体本体１の一端に取り付けるカバー１５Ａに連結管２５を連結しており、その連結管２５に回転継手２６を介して、開閉弁２８を備えた配管２７を接続しているが、図４に示す実施形態とは異なり、その配管２７に圧力調整弁３１、コンプレッサー３２を有する加圧手段を接続している。この加圧手段は、筒体本体１内に、少なくとも０．３〜３ＭＰａの気圧を作用させることができる構成のものである。なお、コンプレッサー３２に代えて、加圧ボンベを用いても良い。この場合には、加圧ボンべを筒体本体１と一緒に回転する構造とすることで回転継手２６の省略が可能となる。加圧ボンぺを用いる場合には、窒素ガスなどの不活性ガスを封入した加圧ボンベを用いることが好ましい。その他の構造は、図１の実施形態と同様である。
【００３８】
次に、図５の製造装置を用いた内面被覆筒体の製造方法を説明する。この実施形態においても、筒体本体１内に自溶合金粉末２を供給し〔図２（ａ）参照〕、次いで、筒体本体１の両端をカバー１５，１５Ａで閉じ、筒体本体１をゆっくりと回転させて、粉末２を軸線方向に均等に行き亘らせる。これまでの工程は、図１に示す製造装置を用いた場合と同様である。
【００３９】
筒体本体１内に自溶合金粉末２を筒体軸線方向均等に配置した後は、筒体支持回転装置３によって、筒体本体１の内周面に３Ｇ以上の遠心力、好ましくは１０Ｇ以上の遠心力が生じる所定の回転速度にまで加速させ、その後はその回転速度に保持する。これにより、筒体本体１内に装入されていた自溶合金粉末２が筒体本体周方向に均等に行き亘り、筒体本体内周面に張りつく。この場合においても、筒体本体１の所定の回転速度への加速に当たっては、筒体本体１の内周面に形成される粉末層の筒体軸線方向の厚さ偏倚がほとんど生じないように（生じても、許容範囲内に納まるように）、内周面位置に短時間で３Ｇ以上の遠心力が生じる回転速度に到達するように加速し、具体的には、内周面の表面粗さを５〜２０μｍＲａに調えた筒体本体１に対して、その筒体本体１の回転速度を次の実験式（Ａ）
τ（秒）＝３×１０^５／Ｄ^３・・・（Ａ）
で求められる時間τを超えない短時間内に前記３Ｇ以上の遠心力が生じる回転速度に到達させるように、筒体本体１の加速を行う。これにより、筒体本体１内周面に、筒体軸線方向に厚さ偏倚のきわめて小さい自溶合金粉末層を形成し張りつかせることができる。
【００４０】
３Ｇ以上の遠心力が生じる所定の回転速度に到達させた後は、筒体本体１をその回転速度に保持し、回転を続けたままで、加熱装置１３によって筒体本体１を加熱して筒体本体内の粉末２を溶融させたのち、溶融状態に保持する。これにより、筒体本体１の内周面上に自溶合金の溶湯層が形成される。この場合にも、加熱装置１３による筒体本体１の加熱温度は、筒体本体内周面に張りついている自溶合金粉末が少なくとも部分的に溶融して粉末同志で及び筒体本体内周面に対して融着しうるように選定すればよく、具体的には、自溶合金に係る状態図における固相線の温度を超えた温度とすればよい。
【００４１】
筒体本体１内に溶湯層が形成された後、コンプレッサー３２を作動させて筒体本体１内の溶湯表面に０．３〜３ＭＰａの気圧を作用させる。これにより、溶湯内に残存している気孔が気圧により圧縮されて体積が減少し、きわめて微細となる。ここで、溶湯表面に作用させる気圧を０．３〜３ＭＰａと設定したのは、この範囲未満では気孔の体積減少効果が小さいためであり、またこの範囲を越えた気圧では、気圧が大きくなって設備コストが大幅に向上するにも係わらず気孔の体積減少効果の向上がさほど生じないためである。筒体本体１内周面の自溶合金粉末を溶融状態に保持し且つ０．３〜３ＭＰａの気圧を作用させる時間は、１０〜１８０秒の範囲内に設定することが好ましい。このように設定する理由は、この時間が１０秒未満では、溶湯の母材に対する拡散を伴った接合が不十分となるか、或いは気孔の圧縮による体積減少効果が不十分となり、一方、１８０秒を超えると、溶湯中の硬質セラミックス微粒子の溶体化や酸化消耗による減少が生じて、硬度を上げることができなくなるとか、酸化物が混入する恐れが生じるためである。
【００４２】
自溶合金粉末を所定時間、溶融状態に保持し且つ０．３〜３ＭＰａの気圧を作用させた後は、その状態を保持したままで冷却段階に移行させて筒体本体１内の溶融自溶合金を凝固させる。以上により、きわめて残存気孔が少なく、硬度の大きい内面被覆を形成できる。
【００４３】
上記した図５の製造装置を用いた内面被覆工程において、筒体本体１の内周面の粉末を加熱溶融し且つその内面に０．３〜３ＭＰａの気圧を作用させる間に筒体本体１に加える回転速度は、前記したように内周面に３Ｇ以上の遠心力が作用する回転速度としている。これは、内周面に３Ｇ以上の遠心力が作用する回転速度とすることで、筒体本体１の内周面に周方向に均等に粉末を分配することができると共に分配後は粉末の周方向及び軸線方向の移動を阻止してその位置に保持でき且つ加熱溶融により生じた溶湯も周方向に一定の厚さに保持できるためである。すなわち、筒体本体１の内周面に作用させる遠心力を、３Ｇ以上とすることで均一厚さの内面被覆を形成することができる。
【００４４】
前記したように、均一厚さの内面被覆を形成するには、筒体本体１を、その内周面に３Ｇ以上の遠心力が作用する回転速度とすればよいが、好ましくは、筒体本体内周面位置に１０Ｇ以上の遠心力が生じる回転速度とする。このように、筒体本体１の内周面にある溶湯層に１０Ｇ以上の遠心力を作用させておくと、その溶湯層内に厚さ方向を含む全領域に亘って均等に圧縮応力が生じ、加圧気体の圧入口となるような受圧挙動のばらつきが希釈された状態となり、その溶湯層の表面に０．３〜３ＭＰａの気圧を作用させている間に、加圧気体が溶湯層内の気孔に貫通するとか溶湯層と筒体本体の界面に貫通するという現象を防止できる。これによって、ピンホールの発生のほとんどない内面被覆を形成できる。
【００４５】
更に、筒体本体内の溶湯層の表面に０．３〜３ＭＰａの気圧を作用させた状態で遠心鋳造を行う際に、筒体本体を、筒体本体内周面位置に２０〜５０Ｇの遠心力が生じる回転速度で回転させておくことも可能である。このように、筒体本体内の溶湯層の表面に０．３〜３ＭＰａの気圧を作用させた状態で遠心鋳造を行う際に、その溶湯層に２０〜５０Ｇの遠心力を作用させておくと、内面被覆内の残存気孔をきわめて微量として硬度を上げることができるのみならず、２０〜５０Ｇの遠心力付加によって、内面被覆の内径側に硬質の微粒子を反遠心集積して表面の硬度を上げることができ、一層硬度の高い内面被覆を備えた内面被覆筒体を製造することができる。
【００４６】
図５の製造装置を用いた上記の実施形態において、回転中の筒体本体１を加熱して内部の自溶合金粉末を溶融させる際には、筒体本体内に空気が入った状態となっているが、本発明はこの構成に限らず、筒体本体内を減圧した状態で行って被覆内気孔を極小化し又は無酸化雰囲気にした状態で行って自溶合金酸化の極小化を図ってもよい。図６は筒体本体内を減圧した状態で自溶合金粉末の加熱溶融操作を行うことの可能な製造装置の１例を示すものである。この製造装置では、回転継手２６に対して、配管２７を介して圧力調整弁３１、コンプレッサー３２を有する加圧手段を接続するのみならず、配管２７Ａを介して開閉弁２８Ａ及び真空ポンプ２９Ａに接続している。その他の構造は、図５に示す製造装置と同様である。図６の製造装置を用いる場合には、筒体本体１内に自溶合金の粉末を供給した後、筒体本体１の両端にカバー１５，１５Ａを取り付けて筒体本体１の両端を閉じ、先ず真空ポンプ２９Ａを作動させて筒体本体１内を減圧した状態で、上記した実施形態と同様に筒体本体１を回転させ、筒体本体１内周面位置に３Ｇ以上の遠心力を作用させ、その状態で自溶合金粉末の加熱溶融を行う。そして、溶融層を形成した後は、真空ポンプ２９Ａを止め、コンプレッサー３２を作動させて筒体本体内の溶湯層の表面に０．３〜３ＭＰａの気圧を作用させ、所定時間その状態に保持した後、冷却・凝固を行う。これにより、一層残存気孔を少なくした内面被覆を形成できる。なお、真空ポンプ２９Ａに代えて、不活性ガスの供給装置を接続することで、筒体本体１内に不活性ガスを満たして無酸化雰囲気とすることができ、その状態で自溶合金粉末の加熱溶融を行うことで、自溶合金の酸化の極小化を図ることができる。
【００４７】
なお、上記した各実施形態では、筒体本体１を加熱する加熱装置１３として、筒体本体１の円周方向の小区間を筒体本体全長に亘って同時に誘導加熱する直線状の誘導子（面焼形コイル）を用いている。この構造の誘導子を用いた加熱装置１３は筒体本体１の全長を短時間で均一に加熱でき、筒体本体１が高速で回転しているので、結局、筒体本体１の全体を短時間で均一に加熱できるという利点を備えている。しかしながら、筒体本体１の全長を加熱する加熱装置１３は、これに限らず、適宜変更可能であり、例えば、筒体本体をほぼ全長に亘って取り囲むように配置され、筒体本体全体を同時に誘導加熱するマルチターンコイル形態の誘導子を用いても良い。
【００４８】
次に、上記した実験式（Ａ）を求めるために行った実験を説明する。
（１）実験１
筒体本体１として、次の仕様の筒体本体の試料Ａ，Ｂ，Ｃを準備した。

【００４９】
これらの試料Ａ，Ｂ，Ｃのそれぞれの内周面に、図１、図２に示す装置を用い、次の条件で自溶合金被覆を行った。

粉末装入：筒体本体１内の１個所に粉末２．５Ｋｇを装入。その後、筒体本体１を７０ｒｐｍで２０秒回転。これによって粉末は筒体本体１内に軸線方向に均等に分散。
筒体本体の加速：筒体本体１を静止状態から３５０ｒｐｍ（遠心力３Ｇが作用する回転速度）までを表１に示す時間で加速。その回転速度に到達後は、その回転速度に保持。
筒体本体の加熱：筒体本体１を１０５０°Ｃに加熱。これにより、内部の粉末もほぼ同温度に昇温し、粉末が部分的に溶融した状態となる。その後、この温度に３０秒間保持。
筒体本体の冷却：放冷
【００５０】
以上の操作によって各試料の筒体本体の内周面に内面被覆を形成した。これらの内面被覆の厚さ及び軸線方向の偏肉率を測定した。その結果を表１及び図７のグラフに示す。
【００５１】
【表１】

【００５２】
表１及び図７のグラフより明らかなように、加速時間を短くするほど、偏肉率が小さくなっており、且つ筒体本体の内周面粗さを大きくするほど、偏肉率が小さくなる。従って、内周面粗さを大きくすることが、被覆の軸線方向の偏肉防止に有効であることを確認できた。
【００５３】
（２）実験２
筒体本体１として、次の仕様の筒体本体の試料Ｄ，Ｅ，Ｆを準備した。

【００５４】
これらの試料Ｄ，Ｅ，Ｆのそれぞれの内周面に、図１、図２に示す装置を用い、次の条件で自溶合金被覆を行った。

粉末装入：筒体本体１内の１個所に表２に示す量の粉末を装入。その後、筒体本体１を７０ｒｐｍで２０秒回転。これによって粉末は筒体本体１内に軸線方向に均等に分散。
筒体本体の加速：筒体本体１を静止状態から表２に示す回転速度（遠心力３Ｇが作用する回転速度）までを表２に示す時間で加速。その回転速度に到達後は、その回転速度に保持。
筒体本体の加熱：筒体本体１を１０２０°Ｃに加熱。これにより、内部の粉末もほぼ同温度に昇温し、粉末が部分的に溶融した状態となる。その後、その温度に６０秒間保持。
筒体本体の冷却：放冷
【００５５】
以上の操作によって各試料の筒体本体の内周面に内面被覆を形成した。これらの内面被覆の厚さ及び軸線方向の偏肉率を測定した。その結果を表２及び図８のグラフに示す。
【００５６】
【表２】

【００５７】
表２及び図８のグラフより明らかなように、加速時間を短くするほど、偏肉率が小さくなっており、且つ内径が大きくなるほど、偏肉率が大きくなり、偏肉率を小さく抑えるには加速時間を短縮する必要があることが判明した。また、図８のグラフ内に、偏肉がほとんど生じない領域を示す曲線３５を書き込み、その曲線３５から次の実験式（Ａ）を得た。
τ（秒）＝３×１０^５／Ｄ^３・・・（Ａ）
〔Ｄは筒体本体の内直径（ｍｍ）〕
従って、内周面粗さを５μｍＲａ以上とした筒体本体に対して自溶合金被覆を行う際には、筒体本体内に粉末を軸線方向均等に配置した後、筒体本体を３Ｇ以上の遠心力が生じる回転速度に到達させる時間を、上記実験式（Ａ）で求められる時間τを超えない値とすることで筒体軸線方向に厚さ偏倚のほとんどない被覆を形成できる。
【００５８】
【実施例】
［実施例１〜４］
（１）次の仕様の筒体本体１及び自溶合金粉末を準備した。

（２）粉末供給及び粉末層形成
筒体本体１を図１に示す製造装置にセットし、その筒体本体１内の１個所に粉末２．５Ｋｇを装入。その後、筒体本体Ｇの両端をカバー１５で閉じた後、その筒体本体１を７０ｒｐｍで２０秒回転。これによって粉末は筒体本体１内に軸線方向に均等に分散。
次いで、筒体本体１の回転を、内周面に２６Ｇ（実施例１），３４Ｇ（実施例２），４２Ｇ（実施例３），５０Ｇ（実施例４）のいずれかの遠心力が作用する回転速度にまで加速し、その回転速度に到達後は、その回転速度に保持。この時の加速度は、２秒で遠心力０から３Ｇに達する加速度とした。
【００５９】
（３）粉末の加熱溶融及び凝固
筒体本体１を１０５０°Ｃに加熱。これにより、内部の粉末もほぼ同温度に昇温し、粉末が部分的に溶融した状態となる。筒体本体１を１０５０°Ｃに加熱・昇温させた後、その温度に３０秒間保持し、その後、加熱を止め、放冷する。これにより、筒体本体１の内面の溶湯層が凝固し、筒体本体の内周面に内面被覆が形成された。
（４）内面被覆の硬度測定
得られた内面被覆は厚さ２ｍｍであった。この内面被覆の深さ０．５ｍｍ位置、１．０ｍｍ位置、１．５ｍｍ位置における硬度を測定した。その結果を表３に示す。
【００６０】
［比較例１〜３］
実施例１と同一仕様の筒体本体１及び自溶合金粉末を用い、粉末層の加熱溶融時に筒体本体１の内周面に加える遠心力を４Ｇ，１０Ｇ，１８Ｇとした以外は、実施例１と同一条件で内面被覆を形成した。得られた内面被覆について、実施例１〜４と同様にして硬度を測定した。その結果も表３に示す。
【００６１】
【表３】

【００６２】
表３の結果から明らかなように、遠心力を高くして遠心鋳造した実施例１〜４は、遠心力を低くした比較例に比べて内面被覆の表面の硬度が極めて高くなっていた。従って、同一の自溶合金を用いながら、本発明の適用により内面被覆の表面硬度を大きくできることを確認できた。実施例２で形成した内面被覆の断面を切断して顕微鏡観察した結果、図３に示すように３層構造となっており、表面層２１ａは硬質セラミックスの微粒子がきわめて多くなった組織となっていた。これにより硬度が大幅に向上したものと考えられる。
【００６３】
［実施例５〜７］
（１）次の仕様の筒体本体１及び自溶合金粉末を準備した。

（２）粉末供給及び粉末層形成
筒体本体１を図５に示す製造装置にセットし、その筒体本体１内の１個所に粉末２．５Ｋｇを装入。その後、筒体本体Ｇの両端をカバー１５，１５Ａで閉じた後、その筒体本体１を７０ｒｐｍで２０秒回転。これによって粉末は筒体本体１内に軸線方向に均等に分散。
次いで、筒体本体１の回転を、内周面に１０Ｇの遠心力が作用する回転速度にまで加速し、その回転速度に到達後は、その回転速度に保持。この時の加速度は、２秒で遠心力０から３Ｇに達する加速度とした。
【００６４】
（３）粉末の加熱溶融及び凝固
筒体本体１を１０５０°Ｃに加熱。これにより、内部の粉末もほぼ同温度に昇温し、粉末が部分的に溶融した状態となる。筒体本体１を１０５０°Ｃに加熱・昇温させた後、コンプレッサー３２を作動させて筒体本体１内に、０．３ＭＰａ（実施例５），０．６ＭＰａ（実施例６），１．０ＭＰａ（実施例７）のいずれかの気圧を作用させ、その温度及び気圧に１５秒間保持し、その後、加熱のみを止め、放冷した。これにより、筒体本体１の内面の溶湯層が凝固し、筒体本体の内周面に内面被覆が形成された。
（４）内面被覆の硬度測定
得られた内面被覆は厚さ２ｍｍであった。この内面被覆の深さ０．５ｍｍ位置、１．０ｍｍ位置、１．５ｍｍ位置における硬度を測定した。その結果を表４に示す。
【００６５】
［比較例４］
実施例５と同一仕様の筒体本体１及び自溶合金粉末を用い、粉末層の加熱溶融時に筒体本体１内に加える気圧を０とした以外は、実施例５と同一条件で内面被覆を形成した。得られた内面被覆について、実施例５〜７と同様にして硬度を測定した。その結果も表４に示す。
【００６６】
【表４】

【００６７】
表４の結果から明らかなように、筒体本体１内の溶湯層に０．３ＭＰａ以上の気圧を作用させて遠心鋳造した実施例５〜７は、気圧を作用させない比較例４に比べて表面の硬度が大きくなっていた。従って、同一の自溶合金を用いながら、本発明の適用により、内面被覆の表面硬度を大きくできることを確認できた。
【００６８】
［実施例８］
実施例２と同一仕様の筒体本体１及び自溶合金粉末を用い、この筒体本体１を図５に示す製造装置にセットし、粉末層の加熱溶融時に筒体本体１の内周面に１．０ＭＰａの気圧を作用させた以外は実施例２と同一条件で（従って、加熱溶融時に、筒体本体１の内周面に３４Ｇの遠心力が作用する条件で）内面被覆を形成した。得られた内面被覆について、実施例２と同様にして硬度を測定した。その結果並びに実施例２の結果を表５に示す。
【００６９】
【表５】

【００７０】
表５の結果から明らかなように、筒体本体１の内周面位置に３４Ｇの遠心力を作用させ、同時に１．０ＭＰａの気圧を作用させて遠心鋳造した実施例８は、気圧を作用させないで行った実施例２に比べて、内面被覆の硬度が更に大きくなっていた。これにより、溶湯層に高Ｇの遠心力を作用させ、同時に高い気圧を作用させることにより、内面被覆の硬度を一層大きくできることが確認できた。
【００７１】
実施例８で形成した内面被覆の断面を切断して顕微鏡観察した結果、この場合にも図３に示すように３層構造となっており、表面層２１ａは硬質セラミックスの微粒子がきわめて多くなった組織となっていた。この表面層２１ａ及び境界層２１ｃの化学成分を測定して表６に示す結果を得た。また、加熱処理する前の自溶合金粉末（ヘガネス＃１５６０）の化学成分も表６に示す。なお、表６中の成分濃度はｍａｓｓ％である。
【００７２】
【表６】

【００７３】
表６から明らかなように、表面層２１ａにはクロム分の濃度が高くなり、一方境界層２１ｃではクロム分濃度が低くなっている。これは、遠心鋳造時の高Ｇの遠心力付与により、溶湯中に析出したクロム化合物系硬質セラミックスの微粒子が表面層内に集積したためである。
【００７４】
【発明の効果】
以上のように、本発明は、筒体本体内周面に自溶合金による内面被覆を遠心鋳造によって形成するに当たり、筒体本体内周面位置に２０〜５０Ｇの遠心力が作用する状態とするか、或いは溶湯層表面に０．３〜３ＭＰａの気圧を作用させた状態とする構成としたことで、従来の方法で形成した内面被覆に比べ、同一の自溶合金を用いながら、内面被覆の表面硬度を高くすることができ、耐摩耗性に優れた内面被覆筒体を製造できるという効果を有している。また、本発明により製造された内面被覆筒体は、優れた耐摩耗性を備えており、これを樹脂成形機シリンダーやスラリー輸送用鋼管などに適用することで、耐摩耗性に優れ、使用寿命の長い樹脂成形機シリンダーやスラリー輸送用鋼管などの製品を得ることができる。
【図面の簡単な説明】
【図１】（ａ），（ｂ）は、本発明の実施形態に係る内面被覆筒体の製造装置を、異なる作動状態で示す概略斜視図
【図２】（ａ），（ｂ），（ｃ），（ｄ）は図１の装置によって筒体本体内周面に樹脂被覆を形成する手順を示す概略断面図
【図３】内面被覆の断面構造を示す概略断面図
【図４】本発明の他の実施形態に係る内面被覆筒体の製造装置の概略斜視図
【図５】本発明の更に他の実施形態に係る内面被覆筒体の製造装置の概略斜視図
【図６】本発明の更に他の実施形態に係る内面被覆筒体の製造装置の概略斜視図
【図７】実験１において得た被覆の軸線方向の偏肉率に対する、筒体本体内周面の表面粗さ及び加速時間の関係を示すグラフ
【図８】実験２において得た被覆の軸線方向の偏肉率に対する、筒体本体内径及び加速時間の関係を示すグラフ
【符号の説明】
１筒体本体
２自溶合金の粉末
３筒体支持回転装置
４受けロール
５押えロール
６可変速モータ
７制御装置
９粉末供給装置
１０粉末供給管
１１ホッパー台車
１３加熱装置
１５，１５Ａカバー
２０内面被覆筒体
２１内面被覆
２５連結管
２６回転継手
２７配管
２８，２８Ａ開閉弁
２９真空ポンプ
３１圧力調整弁
３２コンプレッサー[0001]
BACKGROUND OF THE INVENTION
The present invention is a manufacturing technique of an inner surface coated cylinder in which a self-fluxing alloy coating excellent in wear resistance and corrosion resistance is applied to an inner peripheral surface of a metal cylinder body such as a resin molding machine cylinder and a slurry transporting steel pipe. About.
[0002]
[Prior art]
[Patent Document 1] Japanese Patent Application Laid-Open No. 64-25989
[Patent Document 2] Japanese Patent Laid-Open No. 1-96363
2. Description of the Related Art Conventionally, an inner surface-covered cylinder body in which a self-fluxing alloy coating is applied to an inner peripheral surface of a metal cylinder body such as a steel pipe is known. As a method for manufacturing this inner surface-covered cylinder, in Patent Document 1 (Japanese Patent Laid-Open No. 64-25989), the cylinder body (tube) is rotated so that the centrifugal force on the inner peripheral surface is 3 G or more. In this state, the self-fluxing alloy powder is supplied to form a powder layer having a constant thickness on the inner peripheral surface of the cylindrical body, and then the cylindrical body is heated to a temperature at which the powder layer exhibits a sintered state. Then, the rotation is stopped after the powder layer is attached to the inner peripheral surface of the cylindrical body, and then the cylindrical main body is heated so that its inner peripheral surface temperature is equal to or higher than the melting temperature of the powder. A method is described in which an inner surface coating is formed by melting a powder layer adhering to a peripheral surface and bonding it to a base material in a form accompanied by diffusion. Further, in Patent Document 2 (Japanese Patent Application Laid-Open No. 1-96363), after an amount of self-fluxing alloy powder corresponding to the coating formation thickness is charged into the cylinder body, the cylinder body is connected to the inner circumference. While rotating so that the centrifugal force of the surface is 2G or more and the centrifugal force of the outer peripheral surface is 7G or less, the cylinder body is heated to be equal to or higher than the melting temperature of the powder and adhered to the inner peripheral surface of the cylinder body. A method is described in which an inner coating is formed by melting a powder layer and bonding it to a base material with diffusion. In either method, the self-fluxing alloy powder layer disposed on the inner peripheral surface of the cylindrical body is heated and melted, and is welded to the base material in a form accompanied by diffusion. An inner surface coating of a self-fluxing alloy close to pores can be formed. In particular, in the method described in Patent Document 2, a kind of centrifugal casting is performed in which the powder layer is melted and solidified while the cylinder body is rotated. The pores can be further reduced by applying centrifugal force to the molten metal layer formed on the inner peripheral surface of the cylinder body, and the inner surface coating of the formed self-fluxing alloy has high hardness and excellent wear resistance and corrosion resistance. It was a thing.
[0003]
[Problems to be solved by the invention]
Recently, in order to further improve the wear resistance of the inner surface coating formed on the cylinder body, it has been desired to further improve the hardness of the inner surface coating. In order to increase the hardness, it seems to be sufficient to use a self-fluxing alloy into which hard fine particles such as tungsten carbide are introduced, but it has been found that satisfactory results cannot always be obtained. That is, in the method described in Patent Document 1, although a certain degree of improvement in hardness can be ensured by introducing hard fine particles such as tungsten carbide, the remaining amount of pores compared to the method described in Patent Document 2 On the other hand, in the method described in Patent Document 2, even when hard fine particles such as tungsten carbide are introduced, the hardness of the inner surface coating surface is hardly improved. This is because the specific gravity (≈15) of the fine particles of tungsten carbide, which has been widely used, is significantly larger than the specific gravity (8-9) of the joint metal phase, so that it is away from the surface (inner peripheral surface) of the inner surface coating. It is thought that it moves and does not exist much on the surface. In addition, the hard fine particles gather on the outer diameter side of the inner surface coating, that is, in the boundary region with the base material (cylindrical body), hindering the joining with diffusion of the inner surface coating to the base material, and reducing the adhesive force. A new problem has arisen.
[0004]
The present invention has been made in view of the above circumstances, and it is an object to provide a technique for greatly improving the hardness of at least the surface of the inner surface coating of the self-fluxing alloy formed on the inner peripheral surface of the cylindrical body by centrifugal casting. It is a thing.
[0005]
[Means for Solving the Problems]
The invention according to claim 1 of the present application to solve the above-mentioned problem is an inner surface coating including a step of centrifugally casting and coating a self-fluxing alloy on the inner peripheral surface of a cylindrical body having a cylindrical inner peripheral surface. In the cylindrical body manufacturing method, the centrifugal casting is performed at a rotational speed at which a centrifugal force of 20 to 50 G is generated at the position of the inner peripheral surface, so that among the hard ceramic fine particles present in the molten self-fluxing alloy. By collecting anti-centrifugal particles having a specific gravity lower than the joint metal phase of the molten metal on the inner diameter side of the centrifugal casting system and solidifying the molten metal in this state, an inner surface coating in which the particles having the lower specific gravity are accumulated on the inner diameter side is obtained. It is characterized by. By forming the inner surface coating in which fine particles having a low specific gravity are accumulated on the inner diameter side in this way, the hardness of the surface of the inner surface coating is extremely large, and an inner surface coated cylinder excellent in wear resistance can be manufactured. In addition, as a result of anti-centrifugal accumulation of hard ceramic fine particles on the inner diameter side of the inner surface coating, the concentration of hard ceramic fine particles is reduced on the outer diameter side, and the toughness can be increased and the factor that impedes bonding with diffusion to the base material The inner surface-coated cylinder with excellent impact resistance and peel resistance can be manufactured.
[0006]
According to a second aspect of the present invention, in the first aspect of the invention, a chromium-based boride or carbide in which fine particles having a specific gravity lower than that of the joint metal phase accumulated on the inner diameter side of the inner surface coating are precipitated from a self-fluxing alloy melt. , Ceramic fine particles belonging to any one of borocarbides. Accordingly, the surface hardness of the inner surface coating can be increased while using a commonly used self-fluxing alloy such as a nickel self-fluxing alloy or a cobalt self-fluxing alloy as the self-fluxing alloy.
[0007]
According to a third aspect of the present invention, in the first aspect of the invention, a chromium boride or carbide in which fine particles having a specific gravity lower than that of the joint metal phase accumulated on the inner diameter side of the inner surface coating are precipitated from the molten alloy. , Ceramic fine particles belonging to any one of borocarbides, and hard ceramics having a specific gravity not exceeding the specific gravity of the chromium-based ceramics, introduced into the molten alloy as a component outside the basic composition of the molten alloy This is a fine particle. Thereby, the amount of hard fine particles accumulated on the inner diameter side can be increased, and the surface hardness can be further increased.
[0008]
According to a fourth aspect of the present invention, there is provided a method for manufacturing an inner surface-covered cylinder including a step of centrifugally casting and coating a self-fluxing alloy on the inner peripheral surface of a cylindrical body having a cylindrical inner peripheral surface. The method for producing an inner surface-covered cylindrical body, which is performed in a state where a pressure of 0.3 to 3 MPa is applied to the surface of the molten metal layer. When the inner surface coating of the self-fluxing alloy is formed using centrifugal casting, the amount of pores remaining in the coating becomes very small. Further, in the centrifugal casting process, a pressure of 0.3 to 3 MPa is applied to the surface of the molten metal layer. By making it act and solidify in that state, pores remaining in a minute amount in the molten metal layer are compressed by atmospheric pressure to reduce the volume, and the remaining pores in the obtained inner surface coating become a minute amount in volume ratio. As a result, the hardness of the inner surface coating obtained can be reduced compared to the case of centrifugal casting without applying atmospheric pressure, as a result of suppressing the loss of hardness due to pore space, and this method is also excellent in wear resistance. An inner-coated cylinder can be manufactured.
[0009]
According to a fifth aspect of the present invention, there is provided a method of manufacturing an inner surface-covered cylinder including a step of centrifugally casting and coating a self-fluxing alloy on the inner peripheral surface of a cylindrical body having a cylindrical inner peripheral surface. In the state where the pressure of 0.3 to 3 MPa is applied to the surface of the molten metal layer and the pressure is applied to the surface of the molten metal layer, the rotational speed of the cylindrical body is set to the inner circumference. The rotational speed is such that a centrifugal force of 10 G or more is generated at the surface position. When solidified with a pressure of 0.3 to 3 MPa on the surface of the molten metal layer, as described above, the pores in the molten metal layer are compressed to reduce the volume. Gas may penetrate into the pores in the molten metal layer, and even penetrate to the interface between the molten metal layer and the cylinder body. If solidification is performed in this state, the inner surface coating is considerably larger than the residual pores. In addition, a hole or pinhole leading to the surface is generated. In order to prevent this phenomenon, in the present invention, the rotational speed of the cylindrical body is set to a rotational speed at which a centrifugal force of 10 G or more is generated at the inner peripheral surface position, and a large centrifugal force is applied to the molten metal layer, Pressurized gas is applied by applying atmospheric pressure in a state in which the compressive stress is uniformly generated in the entire region including the thickness direction in the layer and the variation in pressure receiving behavior that becomes the pressure inlet of the pressurized gas is diluted. To prevent penetration. As a result, an inner surface coating having almost no pinholes can be formed.
[0010]
According to a sixth aspect of the present invention, in the method for manufacturing an inner surface-covered cylindrical body, the method includes a step of centrifugally casting and coating a self-fluxing alloy on the inner peripheral surface of a cylindrical body having a cylindrical inner peripheral surface. In the state where the pressure of 0.3 to 3 MPa is applied to the surface of the molten metal layer and the pressure is applied to the surface of the molten metal layer, the rotational speed of the cylindrical body is set to the inner circumference. Centrifugal casting of fine particles having a specific gravity lower than the joint metal phase of the molten metal among the hard ceramic fine particles present in the molten self-melting alloy melt by setting the rotational speed at which a centrifugal force of 20 to 50 G is generated at the surface position. By collecting anti-centrifugation on the inner diameter side and solidifying the molten metal in this state, an inner surface coating in which the low specific gravity fine particles are accumulated on the inner diameter side is obtained. That is, the present invention combines the features of the inventions of the first and fourth aspects. By applying a centrifugal force of 20 to 50 G, hard fine particles are accumulated on the inner diameter side of the inner surface coating so that the surface Hardness can be increased, and by applying a pressure of 0.3 to 3 MPa, the residual pores in the inner surface coating can be made extremely small so that the hardness can be increased, and the inner surface coated cylinder having an inner surface coating with higher hardness Can be manufactured.
[0011]
The invention of claim 7 is the invention of claims 1 to 6, wherein the temperature reached by the self-fluxing alloy melt in the centrifugal casting is changed from a solidus line related to melting and solidification of the self-fluxing alloy to a liquidus temperature. The temperature is not more than 70% from the solidus line side within the solid-liquid coexisting temperature. In order to perform centrifugal casting of the self-fluxing alloy, it is necessary to form a melt layer of the self-fluxing alloy on the surface to be cast. However, if the molten metal temperature at this time increases, metal borides and metals that contribute to hardness improvement Fine particles such as silicides are dissolved or consumed due to oxidation, resulting in a decrease in hardness, and further oxides may be mixed. Therefore, by setting the molten metal temperature as described above, it is possible to prevent a decrease due to solution of hard fine particles, oxidation consumption, or oxide mixing, and to form a coating with high hardness.
[0012]
According to an eighth aspect of the present invention, in the first to sixth aspects of the invention, in the centrifugal casting, a self-fluxing alloy molten metal layer is formed on the inner peripheral surface, and a self-fluxing alloy powder is formed in the cylindrical body. The powder is introduced and heated and melted under the rotation of the cylindrical body. The formation of the self-melting alloy molten metal layer on the inner peripheral surface of the cylindrical body may be performed by a method in which a molten metal is created outside the cylindrical body and the molten metal is supplied into the cylindrical body. As described above, when the self-fluxing alloy is supplied in powder form into the cylindrical body and heated and melted at that position, the handling of the self-fluxing alloy is facilitated and necessary facilities can be simplified.
[0013]
According to a ninth aspect of the present invention, in the first to sixth aspects of the invention, the formation of a self-fluxing alloy molten metal layer on the inner peripheral surface in the centrifugal casting is as follows: The amount of the self-fluxing alloy powder corresponding to the coating formation thickness is evenly arranged in the axial direction of the cylinder, and (2) the cylindrical body is rotated about its axis, and the inner peripheral surface position of the cylindrical body is To reach a rotational speed at which a centrifugal force of 3G or more is generated, the powder in the cylindrical body is stretched on the inner surface of the cylindrical body in the form of spreading in the circumferential direction of the cylindrical body, The following empirical formula (A) is set so that the time to reach the rotational speed at which centrifugal force of 3G or more is generated is controlled so as to suppress the movement of the powder arranged in the cylinder axis direction in the cylinder axis direction.
τ (seconds) = 3 × 10 ⁵ / D ³ ... (A)
[D is the inner diameter of the cylinder (mm)]
By setting the value so as not to exceed the time τ obtained in step (b), a powder layer having almost no thickness deviation is formed in the axial direction and circumferential direction of the cylindrical body, and is attached to the inner surface of the cylindrical body. While continuing the rotation, the cylindrical body is heated so as to simultaneously raise the temperature of the entire cylindrical body, and the powder in the cylindrical body is melted simultaneously. By adopting the above-described steps (1) and (2) when supplying the powder, it is possible to form a self-fluxing alloy powder layer having a very small thickness deviation in the cylinder axial direction on the inner peripheral surface of the cylinder body. It is possible to form an inner surface coating of a self-fluxing alloy having a very small thickness deviation by heating and melting and solidifying the powder layer.
[0014]
According to a tenth aspect of the present invention, in the first to sixth aspects of the invention, in the centrifugal casting, a self-fluxing alloy molten metal layer is formed on the inner peripheral surface, and a self-fluxing alloy powder is formed in the cylindrical body. The powder is introduced and heated and melted under rotation of the cylinder body, and the powder in the cylinder body is melted under reduced pressure. With this configuration, it is possible to effectively remove bubbles from the molten metal layer formed by melting the powder, prevent oxidation of the molten metal layer, and reduce the amount of precipitated fine particles contributing to improvement in hardness with very few residual pores. It is possible to form an inner coating with reduced oxidation consumption and less oxide contamination.
[0015]
The invention according to claim 11 is an inner surface coated cylinder in which an inner surface coating of a self-fluxing alloy is formed on the inner circumferential surface of a cylindrical body having a cylindrical inner circumferential surface, and on the inner diameter side in the inner surface coating, An inner surface-covered cylindrical body characterized in that a hard layer having an increased hardness is formed by distributing fine particles of chromium compound-based hard ceramics at a high density to a level in which a chromium concentration reaches 20 to 40 mass%. Since this inner surface-coated cylinder has a hard layer with increased hardness on the surface (inner peripheral surface) of the inner surface coating, it has excellent wear resistance.
[0016]
The invention according to claim 12 is the invention according to claim 11, wherein a clean layer having a spectroscopic area ratio of non-metallic inclusions of 0.1% or less is formed on the outer diameter side in the inner surface coating. This clean layer has excellent toughness due to a small amount of non-metallic inclusions, and since there are few non-metallic inclusions that impede bonding with diffusion to the base material, the bonding strength to the base material can be increased. The inner surface coating has a structure in which a hard layer on the surface is supported by a clean layer that is excellent in toughness and firmly bonded to the base material, and not only has excellent wear resistance but also excellent impact resistance, peel resistance, etc. Yes.
[0017]
The invention according to claim 13 is a cylindrical support rotating device that horizontally supports and rotates the cylindrical main body, and an amount corresponding to the coating formation thickness in the cylindrical main body supported by the cylindrical support rotating device. A powder supply device for supplying a self-fluxing alloy powder, and a heating device for heating the entire length of the cylinder body supported by the cylinder rotation support device, the cylinder support rotation device, the cylinder body, It is an inner surface-coated cylinder manufacturing apparatus configured to be rotated at a rotation speed at which a centrifugal force of 20 to 50 G is generated at the inner peripheral surface position of the cylinder body. In the manufacturing apparatus of this configuration, an amount of self-fluxing alloy powder corresponding to the coating formation thickness is supplied into the cylinder body supported by the cylinder support rotating apparatus, and the cylinder body is rotated to the inner peripheral surface. After forming the powder layer of the self-fluxing alloy, it is possible to perform centrifugal casting in which the powder layer is heated and melted to form a molten metal layer and then solidified, and the centrifugal casting is performed at the position of the inner peripheral surface. It can carry out at the rotational speed which produces the centrifugal force of 20-50G. For this reason, among the hard ceramic fine particles present in the melt of the self-fluxing alloy being cast, fine particles having a lower specific gravity than the joint metal phase of the molten metal are anti-centrifugally accumulated on the inner diameter side of the centrifugal casting system, and the molten metal is solidified in this state. By doing so, an inner surface coating in which the fine particles having a low specific gravity are accumulated on the inner diameter side can be obtained, and an inner surface coated cylinder having an extremely high surface hardness and excellent wear resistance can be manufactured.
[0018]
According to the fourteenth aspect of the present invention, there is provided a cylindrical support rotating device for horizontally supporting and rotating the cylindrical main body, and an amount corresponding to the coating formation thickness in the cylindrical main body supported by the cylindrical support rotating device. A powder supply device for supplying a self-fluxing alloy powder, a heating device for heating the entire length of the cylinder body supported by the cylinder rotation support device, and an atmospheric pressure of 0.3 to 3 MPa on the inner surface of the cylinder body It is a manufacturing apparatus of the inner surface covering cylinder which has a pressurizing means to act. In the manufacturing apparatus of this configuration, an amount of self-fluxing alloy powder corresponding to the coating formation thickness is supplied into the cylinder body supported by the cylinder support rotating apparatus, and the cylinder body is rotated to the inner peripheral surface. After forming the powder layer of the self-fluxing alloy, it is possible to perform centrifugal casting in which the powder layer is heated and melted to form a molten metal layer and then solidified, and the centrifugal casting is performed on the inner peripheral surface. From the formation of the self-fluxing alloy molten metal layer to the solidification of the molten metal layer, the surface of the molten metal layer can be passed with a pressure of 0.3 to 3 MPa acting, It is possible to manufacture an inner surface-coated cylindrical body having a small inner surface coating with high hardness and excellent wear resistance.
[0019]
According to the fifteenth aspect of the present invention, a cylindrical body supporting and rotating device that horizontally supports and rotates the cylindrical body, and an amount corresponding to the coating formation thickness in the cylindrical body supported by the cylindrical body supporting and rotating device. A powder supply device for supplying a self-fluxing alloy powder, a heating device for heating the entire length of the cylinder body supported by the cylinder rotation support device, and an atmospheric pressure of 0.3 to 3 MPa on the inner surface of the cylinder body The cylinder support rotating device is configured to be capable of rotating the cylinder body at a rotation speed at which a centrifugal force of 10 G or more is generated at an inner peripheral surface position of the cylinder body. It is a manufacturing apparatus of an inner surface covering cylinder. In the manufacturing apparatus of this configuration, centrifugal casting can be performed in a state where an atmospheric pressure of 0.3 to 3 MPa is applied to the surface of the molten metal layer in the cylindrical body, and at that time, the cylindrical body is changed to the cylindrical body. It can be rotated at a rotational speed at which a centrifugal force of 10 G or more is generated at the inner peripheral surface position, preventing the pressurized gas from penetrating through the pores in the molten metal layer or penetrating the interface between the molten metal layer and the cylinder body. Thus, an inner surface coating having almost no pinhole can be formed.
[0020]
According to the sixteenth aspect of the present invention, a cylindrical body supporting and rotating device that horizontally supports and rotates the cylindrical body, and an amount corresponding to the coating formation thickness in the cylindrical body supported by the cylindrical body supporting and rotating device. A powder supply device for supplying a self-fluxing alloy powder, a heating device for heating the entire length of the cylinder body supported by the cylinder rotation support device, and an atmospheric pressure of 0.3 to 3 MPa on the inner surface of the cylinder body The cylinder support rotating device is configured to be capable of rotating the cylinder body at a rotation speed at which a centrifugal force of 20 to 50 G is generated at an inner peripheral surface position of the cylinder body. This is an apparatus for manufacturing an inner surface-coated cylinder. In the manufacturing apparatus of this configuration, centrifugal casting can be performed in a state where an atmospheric pressure of 0.3 to 3 MPa is applied to the surface of the molten metal layer in the cylindrical body, and at that time, the cylindrical body is changed to the cylindrical body. It can be rotated at a rotational speed at which a centrifugal force of 20 to 50 G is generated at the inner peripheral surface position, and the hardness is increased with a very small amount of residual pores in the inner surface coating by applying a pressure of 0.3 to 3 MPa. Not only can be applied, but by applying a centrifugal force of 20 to 50 G, hard particles can be anti-centrifugally accumulated on the inner diameter side of the inner surface coating to increase the surface hardness, and the inner surface coating with a higher hardness inner surface coating A cylinder can be manufactured.
[0021]
According to a seventeenth aspect of the present invention, in the inventions of the fourteenth to sixteenth aspects, the heating device is guided simultaneously along the entire length of the cylindrical body in a small section in the circumferential direction of the cylindrical body supported by the cylindrical body rotation support device. It is set as the structure provided with the inductor to heat. With this configuration, the entire length of the cylindrical body can be simultaneously and quickly heated, and the self-fluxing alloy powder layer can be quickly heated and melted.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 (a) and 1 (b) are schematic perspective views showing an inner surface-coated cylinder manufacturing apparatus according to an embodiment of the present invention in different operating states, and FIGS. 2 (a), (b), (c), ( d) is a schematic cross-sectional view showing a procedure for forming an inner surface coating of a self-fluxing alloy on the inner peripheral surface of the cylindrical body by the manufacturing apparatus of FIG. 1, and 1 is a cylindrical main body having a cylindrical inner peripheral surface. . The cylindrical body 1 is arbitrary as long as it is made of metal, and typical examples include cylinders such as a resin molding machine cylinder and various steel pipes such as a slurry transporting steel pipe. Reference numeral 2 denotes a self-fluxing alloy powder for forming an inner surface coating on the inner peripheral surface of the cylindrical body 1. Examples of the self-fluxing alloy forming the coating include a general-purpose nickel self-fluxing alloy (for example, SFNi4 of JIS, 8303) and a general-purpose cobalt self-fluxing alloy (for example, JIS, 8303 of SFCo3). If necessary, the specific gravity of these self-fluxing alloys may be equal to or less than the specific gravity of ceramics belonging to any one of chromium boride, carbide and borocarbide deposited from the melt of the self-fluxing alloy. Includes hard ceramics having a specific gravity of 7 or less (for example, BN: specific gravity 2.34, B ₄ C: Specific gravity 2.47, Si ₃ N ₄ : Specific gravity 3.2, SiC: Specific gravity 3.21, V ₂ O ₅ : Specific gravity 3.36, VO ₂ : Specific gravity 4.34, TiB ₂ : Specific gravity 4.5, V ₂ O ₃ : Specific gravity 4.87, TiC: Specific gravity 4.94, TiB: Specific gravity 5.09, TiN: Specific gravity 5.43, VO: Specific gravity 5.76, VC: Specific gravity 5.77, ZrB ₂ : Specific gravity 6.08, ZrC: Specific gravity 6.73, NbB ₂ : Specific gravity of 6.97, or a composite of these) may be used.
[0023]
Reference numeral 3 denotes a cylinder support rotating device that horizontally supports and rotates the cylinder body 1. In this embodiment, two receiving rolls 4 that support the lower side of the cylinder body 1 and the cylinder body 1 are provided. A presser roll 5 (not shown in FIG. 1) that presses the upper side, a variable speed motor 6 that rotationally drives the two receiving rolls 4, and a rotational speed and acceleration of the receiving roll 4 by the variable speed motor 6 are controlled. A control device 7 and the like are provided. The variable speed motor 6 and its control device 7 can rotate the cylinder body 1 at a rotational speed at which a centrifugal force of 20 to 50 G acts on the inner peripheral surface position of the cylinder body 1. The configuration is such that acceleration can be achieved so as to reach a rotational speed at which a centrifugal force of 3 G or more is generated within a short time not exceeding the time τ determined by the empirical formula (A). Reference numeral 9 denotes a powder supply device for supplying a self-fluxing alloy powder in an amount corresponding to the coating formation thickness into the cylinder body 1 supported by the cylinder support rotating device 3. In this embodiment, the powder is supplied from the tip. And a hopper carriage 11 that holds the powder supply tube 10 and is movable in the tube axis direction. Reference numeral 13 denotes a heating device that heats the entire length of the cylinder body 1 supported by the cylinder support rotation device 3. In this embodiment, a small section in the circumferential direction of the cylinder body 1 extends over the entire length of the cylinder body. Inductors that are face-fired coils that are heated by induction are used.
[0024]
Next, a method for manufacturing the inner surface-coated cylinder using the inner surface-coated cylinder manufacturing apparatus having the above-described configuration will be described. First, a metallic cylinder body 1 is prepared, and its inner peripheral surface is adjusted to a surface roughness suitable for coating. Here, the surface roughness of the inner peripheral surface of the cylinder body 1 is not limited, but is preferably selected to be about 5 to 20 μm Ra. The surface roughness in this range can be easily formed by inner surface blasting which also serves to clean the inner peripheral surface. If the surface roughness of the inner peripheral surface of the cylinder body is adjusted to 5 to 20 μm Ra, the self-fluxing alloy powder is supplied into the cylinder body 1 and arranged uniformly in the axial direction, and then the cylinder body 1 is rotated at high speed. Thus, there is an advantage that it is possible to suppress the phenomenon that the powder moves in the axial direction of the cylinder and causes the thickness deviation in the middle of the acceleration in the uniform distribution in the circumferential direction. The reason for this seems to be that there is moderate unevenness on the inner peripheral surface of the cylinder body 1 and the powder is caught on it, thereby suppressing the movement of the powder in the cylinder axis direction. As the surface roughness of the inner peripheral surface of the cylindrical body increases, the effect of suppressing the movement of the powder in the axial direction of the cylindrical body tends to increase. In order to use the suppression effect, the surface roughness is set to 5 μmRa or more as described above. However, when this is 20 μmRa or more, it is almost impossible to expect an increase in the effect of suppressing the movement of the powder. On the other hand, the cost of rough surface processing increases. Considering these, the upper limit of the surface roughness is preferably 20 μmRa.
[0025]
Next, the cylindrical body 1 is set on the cylindrical support rotating device 3 to be in a horizontal state, and an amount of self-fluxing alloy powder 2 corresponding to the coating formation thickness is placed inside the horizontal cylindrical body 1. To arrange the cylinders evenly in the cylinder axis direction. Specifically, the powder supply tube 10 of the powder supply device 9 is inserted into the cylindrical body 1 and a predetermined amount of the self-fluxing alloy powder 2 is placed in an appropriate position in the axial direction in the cylindrical body 1 (even at one location or at multiple locations). (See FIG. 2A), the powder supply tube 10 is pulled out, both ends of the cylinder body 1 are closed with appropriate covers 15, and then the cylinder body 1 is connected to the cylinder body 1 The inner powder is rotated at a slow speed that does not reach the circumferential direction of the cylindrical body. By this rotation, the powder 2 charged in the cylindrical main body 1 can be evenly distributed in the axial direction of the cylindrical main body and uniformly arranged in the axial direction [see FIG. 2 (b)]. In this method, when the self-fluxing alloy powder is charged into the cylinder body 1 by the powder supply pipe 10, the powder does not have to be charged evenly in the cylinder axis direction. Benefits that can be obtained.
[0026]
The operation of arranging the self-fluxing alloy powder in an amount corresponding to the coating formation thickness within the cylindrical body 1 evenly in the cylindrical axial direction is not limited to the above-described method, and other methods can be adopted. It is. For example, by inserting the powder supply pipe 10 into the cylinder body 1 and moving the hopper carriage 11 at a constant speed in the cylinder axis direction while discharging powder at a constant flow rate from the tip, the cylinder body The powder can be evenly arranged in the axial direction within 1. Further, as the powder supply pipe 10 to be charged into the cylindrical body 1, a slit-like discharge port extending in the axial direction or a discharge port composed of a large number of holes arranged in the axial direction is formed on the side surface thereof. With the discharge port closed or upward, the self-fluxing alloy powder is put in the powder supply tube 10 evenly in the axial direction, and the powder supply tube 10 is inserted into the cylindrical body 1 and then the discharge port is opened or downward. By adopting a method of supplying the self-fluxing alloy powder in the powder supply pipe 10 into the cylindrical body 1, the cylindrical axial direction can be evenly arranged.
[0027]
After the self-fluxing alloy powder 2 is evenly arranged in the cylindrical body axial direction in the cylindrical body 1, the cylindrical body 1 is rotated around the axis by the cylindrical support rotating device 3, and the inside of the cylindrical body 1 is A rotational speed at which a centrifugal force of 20 to 50 G is generated at the peripheral surface position is reached. By this rotation, the self-fluxing alloy powder 2 charged in the cylindrical body 1 spreads evenly in the circumferential direction of the cylindrical body and sticks to the inner circumferential surface of the cylindrical body [see FIG. 2 (c)]. Thus, the powder 2 spread evenly in the circumferential direction of the cylindrical body and stuck to the inner peripheral surface of the cylindrical body is above the rotational speed at which a centrifugal force of 3 G or more is generated at the position of the inner peripheral surface. It hardly moves on the inner peripheral surface and is held in that position. Therefore, a uniformly thick powder layer is formed and maintained on the inner peripheral surface of the cylinder body. However, at the rotational speed at which a centrifugal force of about 1G to 2G is generated at the position of the inner peripheral surface during acceleration of the cylindrical main body 1, the powder is temporarily attached to the inner peripheral surface of the cylindrical main body, but the restraining force based on the centrifugal force. Therefore, the powder has a right-handed or left-handed helical displacement due to the microscopic direction of the inner peripheral surface of the cylindrical body 1 and the powder moves in the axial direction of the cylindrical body. There is a tendency for thickness deviation in the body axis direction to occur. Therefore, when the rotation of the cylindrical body 1 is started and accelerated to a predetermined rotational speed, such a thickness deviation in the axial direction of the cylindrical body hardly occurs (even if it occurs, it falls within the allowable range). Ii) Accelerate so as to reach a rotational speed at which a centrifugal force of 3 G or more is generated at the inner peripheral surface position of the cylindrical body in a short time. Specifically, with respect to the cylindrical body 1 whose surface roughness is adjusted to 5 to 20 μmRa, the rotational speed of the cylindrical body 1 is expressed by the following empirical formula (A).
τ (seconds) = 3 × 10 ⁵ / D ³ ... (A)
The cylinder body 1 is accelerated so as to reach the rotational speed at which the centrifugal force of 3 G or more is generated within a short time not exceeding the time τ determined in step (b). Thereby, a self-fluxing alloy powder layer having a very small thickness deviation in the axial direction of the cylinder can be formed and adhered to the inner peripheral surface of the cylinder body 1. The basis for this empirical formula (A) will be described later.
[0028]
After allowing the cylinder body 1 to reach a predetermined rotation speed at which a centrifugal force of 20 to 50 G is generated at the inner peripheral surface position, the cylinder body 1 is held at the rotation speed, and the rotation device 13 is kept rotating. Thus, the cylindrical body 1 is heated to melt the powder 2 in the cylindrical body, and then held in a molten state. Thereby, a molten metal layer of a self-fluxing alloy is formed on the inner peripheral surface of the cylindrical body 1. Here, the molten state in the molten metal layer does not necessarily mean only the state in which the entire powder is completely melted, but at least a part of the powder is melted so that both the powder and the inner peripheral surface of the cylindrical body It means a state that can be fused. Therefore, the heating temperature of the cylindrical body 1 by the heating device 13 is such that the self-fluxing alloy powder sticking to the inner peripheral surface of the cylindrical main body is at least partially melted and is in powder form with respect to the inner peripheral surface of the cylindrical main body. What is necessary is just to select so that it can fuse | melt, and what is necessary is just to set it as the temperature exceeding the temperature of the solidus line in the phase diagram concerning a self-fluxing alloy specifically ,.
[0029]
On the other hand, the higher the heating temperature of the cylinder body 1, the higher the melting rate of the powder, and finally it is completely melted. And, it was thought that by making the powder layer completely melted, it is possible to form a denser fusion-coating layer without pores or pinholes, but the present inventors have confirmed It has been found that it is possible to form a dense fusion-bonding layer having no pores or pinholes without necessarily completely melting the powder. In addition, when the powder layer is in a completely melted state, the coating thickness can be made uniform in the cylinder axis direction due to the fluidity of the melt layer, and thus the thickness is applied to the powder layer attached to the inner peripheral surface of the cylinder body. Even if there is a deviation, it can be corrected. However, if there is almost no thickness deviation when the powder layer is formed as described above, it is not necessary to correct the thickness deviation as a completely molten state. . On the other hand, if the powder layer is to be completely melted, the heating temperature of the cylinder body 1 must be increased, and naturally, the heat energy consumption increases and the heating time also increases. In addition, when the molten state exceeds the liquidus temperature of the self-fluxing alloy, particles such as metal borides and metal silicides that contribute to the improvement of hardness in the self-fluxing alloy are reduced by solution or oxidation consumption, There are also disadvantages in that the hardness decreases or oxides are mixed. Considering these things, the upper limit of the heating temperature of the cylinder body 1 is selected so that the temperature of the self-fluxing alloy in the cylinder body does not exceed the temperature of the liquidus relating to the melting of the self-fluxing alloy. Preferably, the temperature reached by the self-fluxing alloy melt is 70% from the solidus line side within the solid-liquid coexistence temperature from the solidus line to the liquidus temperature related to melting and solidification of the self-fluxing alloy. It is preferable that the temperature be equal to or lower than the temperature located at.
[0030]
The rotation speed of the cylinder body 1 when the self-fluxing alloy powder layer is heated and melted is set to a rotation speed at which a centrifugal force of 20 to 50 G acts as described above. Conventionally, when the self-fluxing alloy powder layer formed on the inner surface of the cylinder body is melted and densified, bubbles are removed from the melt layer of the self-fluxing alloy by rotating the cylinder body 1 and applying a centrifugal force. It is known that the effect is increased, and even the method described in Patent Document 2 described above is melted in a state where a centrifugal force of 2 G or more acts. However, the bubble removal effect by the centrifugal force is improved with the increase of the centrifugal force until the centrifugal force is increased to about 7-8G, but the bubble removal effect is not so much improved even if the centrifugal force is increased further. For this reason, conventionally, the centrifugal force is at most about 10 G or less. On the other hand, in this embodiment, a centrifugal force of 20 to 50G is adopted. By using such a high G centrifugal force, not only the bubble removal effect but also the anti-centrifugal accumulation effect on the inner diameter side of the hard ceramic fine particles having a specific gravity lower than the joint metal phase present in the molten metal is obtained. Thus, the hardness of the surface layer can be greatly improved. That is, the joint metal in the melt of the self-fluxing alloy is Ni (specific gravity 8.9), Cr (specific gravity 8.5), Co (specific gravity 8.85) or the like. Chromium boride (CrB: specific gravity 6.2), carbide (Cr ₃ C ₂ : Specific gravity 6.68, Cr ₇ C ₃ : Specific gravity of 6.92) or borocarbide having a composition in which these are combined (specific gravity of about 6 to 7) or the like, there are hard ceramic fine particles having a specific gravity in the range of 6 to 7. These hard ceramic fine particles have a low specific gravity compared to the joint metal phase, but the difference is not so large. Therefore, the centrifugal force of about 3 to 8 G, which has been conventionally performed, is anti-centrifugally accumulated on the inner diameter side of the molten metal layer. However, by using a high G centrifugal force such as 20 to 50 G, anticentrifugation could be performed on the inner diameter side.
[0031]
The time for holding the self-fluxing alloy powder on the inner peripheral surface of the cylindrical body 1 in the molten state is preferably set within a range of 10 to 180 seconds. If this time is less than 10 seconds, bonding with diffusion of the molten metal to the base metal becomes insufficient or accumulation on the inner diameter side of the hard ceramic fine particles having a low specific gravity is insufficient. When the hard ceramic fine particles in the molten metal are dissolved or decreased due to oxidative consumption, the hardness cannot be increased or oxides may be mixed. For these reasons, when the cylindrical body 1 is heated to melt the powder 2 in the cylindrical body and is maintained in a molten state, the cylindrical body 1 is heated by the temperature of the self-fluxing alloy powder. While the temperature of the solidus line related to the melting of the self-fluxing alloy is exceeded, the temperature of the liquidus line is preferably not exceeded, and the time for maintaining the molten state is preferably selected as 10 to 180 seconds.
[0032]
After the self-fluxing alloy powder is held in a molten state for a predetermined time, the molten self-fluxing alloy in the cylinder body 1 is solidified by shifting to the cooling stage while continuing to rotate the cylinder body 1. For this cooling, any cooling method such as in-furnace cooling, heat insulation cooling, cooling, air cooling or the like can be adopted. However, if the cooling is too fast, the solidified alloy coating is solidified due to thermal stress. Therefore, it is desirable to experimentally obtain a cooling schedule for a short time that does not cause cracking.
[0033]
As described above, the self-fluxing alloy can be fused at once to the entire inner peripheral surface of the cylinder body to form the self-fluxing alloy coating, and then the cylinder body 1 is removed from the apparatus, whereby FIG. As shown to (d), the inner surface covering cylinder 20 which has the inner surface coating 21 of a self-fluxing alloy on the inner peripheral surface of the cylinder main body 1 can be manufactured. The inner surface coating 21 of the obtained self-fluxing alloy has a very high surface (inner peripheral surface) hardness, and the thickness deviation is extremely small in the cylindrical axis direction and the circumferential direction.
[0034]
When the cross section of the inner surface coating 21 of the inner surface coating cylinder 20 obtained by the above steps was observed with a microscope, as shown schematically in FIG. 3, the inner surface coating 21 was composed of a surface layer 21a, an intermediate layer 21b, and a boundary layer. The layer structure was 21c. The surface layer 21a has a structure in which a white task portion and a black task portion are mixed, and each task portion has a lot of fine precipitates in the joint metal (matrix metal) and is finely distributed. It was an organization. This surface layer 21a exhibited extremely high hardness (for example, 818 to 927 Hv) as shown in Examples 1 to 4 described later. As the fine-particle precipitates, plate-like, lump-like, and spot-like ones are seen, but when their chemical components were measured, most of the metal components were chromium. Therefore, the surface layer 21a is a hard layer whose hardness is increased by distributing fine particles of chromium compound hard ceramics such as chromium boride, carbide and borocarbide at a high density. Seems to indicate. The intermediate layer 21b has a structure in which a small amount of fine precipitates are dispersed in the matrix metal, and the hardness is lower than that of the surface layer. The boundary layer 21c has a structure in which a very small amount of eutectic precipitates are dispersed in a matrix in the matrix metal, and the hardness is further lowered. As a result of centrifugal casting at high G, non-metallic inclusions such as hard ceramic fine particles contained in the matrix metal move to the inner diameter side, and the boundary layer 21c is mostly a clean layer made of matrix metal. It seems that it was because of Since this boundary layer 21c is a clean layer having almost no non-metallic inclusions, it has excellent toughness, and supports the hard surface layer 21a well in combination with the gradient composition structure brought about by the intermediate layer 21b. The base material (tubular body 1) is joined with good diffusion. As described above, the inner surface coating 21 has characteristics of having appropriate toughness and good adhesion to the base material despite the extremely high hardness of the surface (inner peripheral surface), wear resistance, Excellent impact resistance and peel resistance.
[0035]
The surface layer 21a of the inner surface coating 21 has higher hardness and higher wear resistance as the chromium content is higher. However, if the hardness is too high, manufacture becomes difficult. Therefore, the chromium content concentration of the surface layer 21a is preferably about 20 to 40 mass%. In the boundary layer 21a, the smaller the non-metallic inclusions, the better the toughness and the better the bonding characteristics accompanied by the diffusion to the base material. Specifically, the specular area ratio of the non-metallic inclusions is preferably 0. 0.1% or less is preferable.
[0036]
In the above embodiment, when the rotating cylinder body 1 is heated to melt the self-fluxing alloy powder inside, the cylinder body is in a state where air is contained. Not limited to the configuration, the self-fluxing alloy oxidation may be minimized by performing in a state where the inside of the cylinder body is decompressed to minimize the pores in the coating or in a non-oxidizing atmosphere. FIG. 4 shows an example of a manufacturing apparatus used for performing the heating and melting operation of the self-fluxing alloy powder in a state where the inside of the cylindrical body is decompressed. In this manufacturing apparatus, a connecting pipe 25 is connected to a cover 15A attached to one end of the cylinder body 1, a pipe 27 is connected to the connecting pipe 25 via a rotary joint 26, and an open / close valve 28 and a pipe 27 are connected to the pipe 27. A vacuum pump 29 is connected. The other structure is the same as that of the manufacturing apparatus shown in FIG. When using the manufacturing apparatus of FIG. 4, after supplying the self-fluxing alloy powder 2 into the cylindrical body 1 as shown in FIG. 2 (a), the both ends of the cylindrical body 1 as shown in FIG.

Covers

15 and 15A are attached, both ends of the cylinder body 1 are closed, the inside is communicated with the vacuum pump 29, and the inside of the cylinder body 1 is decompressed by operating the vacuum pump 29. The cylindrical body 1 is rotated, and a centrifugal force of 20 to 50 G is applied to the position of the inner peripheral surface of the cylindrical body 1, and the self-fluxing alloy powder is heated and melted and solidified in this state. As a result, an inner surface coating having a very hard surface layer can be formed. Further, since the inside of the cylinder body 1 is depressurized during heating and melting, the effect of removing bubbles in the molten metal is great, and an inner surface coating with extremely small residual pores can be formed. By connecting an inert gas supply device instead of the vacuum pump 29, the cylinder body 1 can be filled with the inert gas to form a non-oxidizing atmosphere. By performing heat melting and solidification, the oxidation of the self-fluxing alloy can be minimized. In each of the embodiments described above, when a self-fluxing alloy powder layer is formed on the inner peripheral surface of the cylinder body 1, a centrifugal force of 20 to 50 G is already applied to the inner peripheral surface position of the cylinder body. However, the present invention is not limited to this case, and at the time of forming the self-fluxing alloy powder layer, the cylindrical body 1 is set to a rotational speed at which an appropriate centrifugal force of 3 G or more acts on the inner peripheral surface position, and in this state the powder layer Then, the molten metal layer is formed by heating and melting, and then the rotational speed of the cylinder body 1 may be increased to apply a centrifugal force of 20 to 50 G to solidify in that state.
[0037]
FIG. 5 shows an apparatus for producing an inner surface-covered cylinder according to another embodiment of the present invention. In the manufacturing apparatus of this embodiment, similarly to the embodiment shown in FIG. 4, the connecting pipe 25 is connected to the cover 15 A attached to one end of the cylindrical body 1, and the connecting pipe 25 is connected via the rotary joint 26. Although the piping 27 provided with the on-off valve 28 is connected, the pressurization means which has the pressure regulation valve 31 and the compressor 32 is connected to the piping 27 unlike the embodiment shown in FIG. This pressurizing means is configured to be able to apply an atmospheric pressure of at least 0.3 to 3 MPa to the cylindrical body 1. A pressure cylinder may be used in place of the compressor 32. In this case, the rotary joint 26 can be omitted by adopting a structure in which the pressure cylinder is rotated together with the cylindrical body 1. When using a pressure cylinder, it is preferable to use a pressure cylinder in which an inert gas such as nitrogen gas is sealed. Other structures are the same as those of the embodiment of FIG.
[0038]
Next, the manufacturing method of the inner surface covering cylinder using the manufacturing apparatus of FIG. 5 will be described. Also in this embodiment, the self-fluxing alloy powder 2 is supplied into the cylindrical body 1 [see FIG. 2 (a)], and then both ends of the cylindrical body 1 are closed by the

covers

15 and 15A. Slowly rotate to spread the powder 2 evenly in the axial direction. The steps so far are the same as in the case of using the manufacturing apparatus shown in FIG.
[0039]
After the self-fluxing alloy powder 2 is uniformly disposed in the cylindrical body axial direction in the cylindrical body 1, a centrifugal force of 3 G or more, preferably 10 G or more is applied to the inner peripheral surface of the cylindrical body 1 by the cylindrical support rotating device 3. Is accelerated to a predetermined rotational speed at which the centrifugal force is generated, and then maintained at that rotational speed. As a result, the self-fluxing alloy powder 2 charged in the cylinder body 1 spreads evenly in the circumferential direction of the cylinder body and sticks to the inner circumferential surface of the cylinder body. Even in this case, when the cylinder body 1 is accelerated to a predetermined rotational speed, the thickness deviation of the powder layer formed on the inner peripheral surface of the cylinder body 1 in the cylinder axis direction hardly occurs ( Even if it occurs, it is accelerated so as to reach a rotational speed at which a centrifugal force of 3G or more is generated in a short time on the inner peripheral surface position, specifically, the surface roughness of the inner peripheral surface For the cylinder body 1 adjusted to 5 to 20 μmRa, the rotational speed of the cylinder body 1 is expressed by the following empirical formula (A):
τ (seconds) = 3 × 10 ⁵ / D ³ ... (A)
The cylinder body 1 is accelerated so as to reach the rotational speed at which the centrifugal force of 3 G or more is generated within a short time not exceeding the time τ determined in step (b). Thereby, a self-fluxing alloy powder layer having a very small thickness deviation in the axial direction of the cylinder can be formed and adhered to the inner peripheral surface of the cylinder body 1.
[0040]
After reaching a predetermined rotational speed at which a centrifugal force of 3 G or more is generated, the cylindrical body 1 is heated by the heating device 13 while the cylindrical body 1 is held at the rotational speed and the rotation is continued. After melting the powder 2 in the body, it is kept in a molten state. Thereby, a molten metal layer of a self-fluxing alloy is formed on the inner peripheral surface of the cylindrical body 1. Also in this case, the heating temperature of the cylinder body 1 by the heating device 13 is such that the self-fluxing alloy powder sticking to the inner peripheral surface of the cylinder main body is at least partially melted by the powder and the inner peripheral surface of the cylindrical main body. The temperature may be selected so as to be able to be fused with respect to the temperature, and more specifically, the temperature may be higher than the temperature of the solidus in the phase diagram related to the self-fluxing alloy.
[0041]
After the molten metal layer is formed in the cylindrical body 1, the compressor 32 is operated to apply a pressure of 0.3 to 3 MPa to the molten metal surface in the cylindrical body 1. Thereby, the pores remaining in the molten metal are compressed by the atmospheric pressure, the volume is reduced, and the pores become extremely fine. Here, the reason why the atmospheric pressure acting on the molten metal surface was set to 0.3 to 3 MPa is that the pore volume reduction effect is small below this range, and at the atmospheric pressure exceeding this range, the atmospheric pressure becomes large. This is because the improvement in the effect of reducing the volume of the pores does not occur so much although the equipment cost is greatly improved. The time during which the self-fluxing alloy powder on the inner peripheral surface of the cylinder body 1 is kept in a molten state and the pressure of 0.3 to 3 MPa is applied is preferably set within a range of 10 to 180 seconds. The reason for setting in this way is that if this time is less than 10 seconds, the joining with diffusion of the molten metal to the base metal becomes insufficient, or the volume reduction effect due to the compression of the pores becomes insufficient, while 180 seconds. This is because the hardness of the hard ceramic fine particles in the molten metal may decrease due to solution or oxidation consumption, and the hardness may not be increased or oxide may be mixed.
[0042]
After holding the self-fluxing alloy powder in a molten state for a predetermined time and applying an atmospheric pressure of 0.3 to 3 MPa, the state is maintained and the process is shifted to the cooling stage to melt the self-melting alloy in the cylinder body 1. Solidify the alloy. As described above, it is possible to form an inner surface coating with extremely few residual pores and high hardness.
[0043]
In the inner surface coating process using the manufacturing apparatus of FIG. 5 described above, the powder on the inner peripheral surface of the cylindrical main body 1 is heated and melted and the atmospheric pressure of 0.3 to 3 MPa is applied to the inner surface of the cylindrical main body 1. The rotational speed to be applied is the rotational speed at which a centrifugal force of 3 G or more acts on the inner peripheral surface as described above. This is because the rotational speed at which a centrifugal force of 3 G or more acts on the inner peripheral surface allows the powder to be evenly distributed in the circumferential direction on the inner peripheral surface of the cylindrical body 1 and after the distribution, This is because the movement in the direction and the axial direction can be prevented and held at that position, and the molten metal generated by heating and melting can also be held at a constant thickness in the circumferential direction. That is, the inner surface coating having a uniform thickness can be formed by setting the centrifugal force applied to the inner peripheral surface of the cylindrical body 1 to 3 G or more.
[0044]
As described above, in order to form an inner surface coating having a uniform thickness, the cylindrical body 1 may be set to a rotational speed at which a centrifugal force of 3 G or more acts on the inner peripheral surface thereof. The rotational speed is such that a centrifugal force of 10 G or more is generated at the position of the inner peripheral surface. As described above, when a centrifugal force of 10 G or more is applied to the molten metal layer on the inner peripheral surface of the cylindrical body 1, a compressive stress is uniformly generated over the entire region including the thickness direction in the molten metal layer. While the pressure receiving behavior variation that becomes the pressurized gas pressure inlet is in a diluted state, and the pressure of 0.3 to 3 MPa is applied to the surface of the molten metal layer, the pressurized gas is in the molten metal layer It is possible to prevent the phenomenon of penetrating through the pores or penetrating the interface between the molten metal layer and the cylindrical body. As a result, it is possible to form an inner surface coating that hardly generates pinholes.
[0045]
Furthermore, when performing centrifugal casting in a state in which a pressure of 0.3 to 3 MPa is applied to the surface of the molten metal layer in the cylindrical body, the cylindrical body is centrifuged at an inner peripheral surface position of 20 to 50 G. It is also possible to rotate at a rotational speed at which force is generated. Thus, when performing centrifugal casting in a state where a pressure of 0.3 to 3 MPa is applied to the surface of the molten metal layer in the cylinder body, a centrifugal force of 20 to 50 G is applied to the molten metal layer. , Not only can the residual pores in the inner surface coating be made extremely small, but also the hardness can be increased, and by applying centrifugal force of 20 to 50 G, hard particles are anti-centrifugally accumulated on the inner diameter side of the inner surface coating to increase the surface hardness. It is possible to manufacture an inner surface-coated cylinder having an inner surface coating with higher hardness.
[0046]
In the above-described embodiment using the manufacturing apparatus of FIG. 5, when the rotating cylinder body 1 is heated to melt the self-fluxing alloy powder therein, air enters the cylinder body. However, the present invention is not limited to this configuration, and is performed in a state in which the inside of the cylindrical body is decompressed to minimize the inner pores of the coating or in a non-oxidizing atmosphere to minimize self-fluxing alloy oxidation. Also good. FIG. 6 shows an example of a manufacturing apparatus capable of performing the heating and melting operation of the self-fluxing alloy powder in a state where the pressure inside the cylinder body is reduced. In this manufacturing apparatus, not only a pressure adjusting valve 31 and a pressurizing means having a compressor 32 are connected to the rotary joint 26 via a pipe 27, but also connected to an on-off valve 28A and a vacuum pump 29A via a pipe 27A. doing. The other structure is the same as that of the manufacturing apparatus shown in FIG. In the case of using the manufacturing apparatus of FIG. 6, after supplying self-fluxing alloy powder into the cylinder body 1, covers 15 and 15 A are attached to both ends of the cylinder body 1 to close both ends of the cylinder body 1, First, in a state where the vacuum pump 29A is operated and the inside of the cylinder body 1 is depressurized, the cylinder body 1 is rotated in the same manner as in the above-described embodiment, and a centrifugal force of 3 G or more acts on the inner peripheral surface position of the cylinder body 1. In this state, the self-fluxing alloy powder is heated and melted. After forming the molten layer, the vacuum pump 29A is stopped, the compressor 32 is operated, and a pressure of 0.3 to 3 MPa is applied to the surface of the molten metal layer in the cylindrical body, and the state is maintained for a predetermined time. Then, cooling and solidification are performed. Thereby, it is possible to form an inner surface coating with fewer remaining pores. By connecting an inert gas supply device instead of the vacuum pump 29A, the cylinder body 1 can be filled with an inert gas to form a non-oxidizing atmosphere. By performing the heat melting, the oxidation of the self-fluxing alloy can be minimized.
[0047]
In each of the above-described embodiments, as the heating device 13 for heating the cylindrical body 1, a linear inductor (inductively heating a small section in the circumferential direction of the cylindrical body 1 simultaneously over the entire length of the cylindrical body ( A face-fired coil) is used. The heating device 13 using the inductor having this structure can uniformly heat the entire length of the cylindrical body 1 in a short time, and the cylindrical body 1 rotates at a high speed. It has the advantage that it can be heated uniformly over time. However, the heating device 13 for heating the entire length of the cylindrical body 1 is not limited to this, and can be changed as appropriate. For example, the heating apparatus 13 is disposed so as to surround the entire length of the cylindrical body, and the entire cylindrical body is simultaneously An inductor in the form of a multi-turn coil that performs induction heating may be used.
[0048]
Next, an experiment conducted for obtaining the above-described empirical formula (A) will be described.
(1) Experiment 1
As the cylinder body 1, samples A, B, and C of the cylinder body having the following specifications were prepared.

[0049]
The inner peripheral surfaces of these samples A, B, and C were coated with a self-fluxing alloy under the following conditions using the apparatus shown in FIGS.

Powder charging: 2.5 kg of powder was charged in one place in the cylinder body 1. Thereafter, the cylinder body 1 is rotated at 70 rpm for 20 seconds. As a result, the powder is uniformly distributed in the axial direction in the cylindrical body 1.
Acceleration of the cylinder body: The cylinder body 1 is accelerated from the stationary state to 350 rpm (rotational speed at which the centrifugal force 3G acts) in the time shown in Table 1. After reaching that rotation speed, keep it at that rotation speed.
Heating of cylinder body: The cylinder body 1 is heated to 1050 ° C. Thereby, the temperature of the internal powder is also raised to substantially the same temperature, and the powder is partially melted. Then hold at this temperature for 30 seconds.
Cylinder body cooling: Cooling
[0050]
By the above operation, an inner surface coating was formed on the inner peripheral surface of the cylindrical body of each sample. The thickness of these inner surface coatings and the thickness deviation in the axial direction were measured. The results are shown in Table 1 and the graph of FIG.
[0051]
[Table 1]

[0052]
As is apparent from the graphs in Table 1 and FIG. 7, the thickness deviation rate decreases as the acceleration time is shortened, and the thickness deviation rate decreases as the inner peripheral surface roughness of the cylindrical body increases. . Therefore, it was confirmed that increasing the roughness of the inner peripheral surface is effective in preventing uneven thickness in the axial direction of the coating.
[0053]
(2) Experiment 2
As the cylinder body 1, samples D, E, and F of a cylinder body having the following specifications were prepared.

[0054]
Self-fluxing alloy coating was performed on the inner peripheral surfaces of these samples D, E, and F using the apparatus shown in FIGS. 1 and 2 under the following conditions.

Powder charging: The amount of powder shown in Table 2 was charged at one location in the cylinder body 1. Thereafter, the cylinder body 1 is rotated at 70 rpm for 20 seconds. As a result, the powder is uniformly distributed in the axial direction in the cylindrical body 1.
Acceleration of the cylinder body: The cylinder body 1 is accelerated from the stationary state to the rotation speed shown in Table 2 (rotation speed at which the centrifugal force 3G acts) in the time shown in Table 2. After reaching that rotation speed, keep it at that rotation speed.
Heating of the cylinder body: The cylinder body 1 is heated to 1020 ° C. Thereby, the temperature of the internal powder is also raised to substantially the same temperature, and the powder is partially melted. Then hold at that temperature for 60 seconds.
Cylinder body cooling: Cooling
[0055]
By the above operation, an inner surface coating was formed on the inner peripheral surface of the cylindrical body of each sample. The thickness of these inner surface coatings and the thickness deviation in the axial direction were measured. The results are shown in Table 2 and the graph of FIG.
[0056]
[Table 2]

[0057]
As is apparent from the graphs in Table 2 and FIG. 8, the shorter the acceleration time, the smaller the wall thickness ratio, and the larger the inner diameter, the larger the wall thickness ratio, and to keep the wall thickness ratio small. It turns out that the acceleration time needs to be shortened. In addition, a curve 35 indicating a region where uneven thickness hardly occurs is written in the graph of FIG. 8, and the following empirical formula (A) is obtained from the curve 35.
τ (seconds) = 3 × 10 ⁵ / D ³ ... (A)
[D is the inner diameter of the cylinder body (mm)]
Accordingly, when self-fluxing alloy coating is performed on a cylinder body having an inner peripheral surface roughness of 5 μmRa or more, after the powder is evenly arranged in the axial direction in the cylinder body, the cylinder body is 3G or more. By setting the time for reaching the rotational speed at which the centrifugal force is generated to a value that does not exceed the time τ determined by the empirical formula (A), it is possible to form a coating with almost no thickness deviation in the cylinder axis direction.
[0058]
【Example】
[Examples 1 to 4]
(1) A cylindrical body 1 and self-fluxing alloy powder having the following specifications were prepared.

(2) Powder supply and powder layer formation
The cylindrical body 1 is set in the manufacturing apparatus shown in FIG. 1 and charged with 2.5 kg of powder in one place in the cylindrical body 1. Thereafter, both ends of the cylinder body G are closed with the cover 15, and then the cylinder body 1 is rotated at 70 rpm for 20 seconds. As a result, the powder is uniformly distributed in the axial direction in the cylindrical body 1.
Subsequently, the centrifugal force of any one of 26G (Embodiment 1), 34G (Embodiment 2), 42G (Embodiment 3), and 50G (Embodiment 4) acts on the inner peripheral surface of the rotation of the cylindrical body 1. Accelerates to the rotational speed, and maintains the rotational speed after reaching the rotational speed. The acceleration at this time was an acceleration reaching a centrifugal force from 0 to 3 G in 2 seconds.
[0059]
(3) Heat melting and solidification of powder
The cylinder body 1 is heated to 1050 ° C. Thereby, the temperature of the internal powder is also raised to substantially the same temperature, and the powder is partially melted. After heating and raising the temperature of the cylinder body 1 to 1050 ° C., the temperature is maintained at that temperature for 30 seconds, and then the heating is stopped and the mixture is allowed to cool. Thereby, the molten metal layer of the inner surface of the cylinder body 1 was solidified, and an inner surface coating was formed on the inner peripheral surface of the cylinder body.
(4) Hardness measurement of inner coating
The resulting inner coating was 2 mm thick. The hardness of the inner surface coating at a depth of 0.5 mm, 1.0 mm and 1.5 mm was measured. The results are shown in Table 3.
[0060]
[Comparative Examples 1-3]
Example 1 except that the cylindrical body 1 and self-fluxing alloy powder having the same specifications as in Example 1 were used, and the centrifugal force applied to the inner peripheral surface of the cylinder body 1 when the powder layer was heated and melted was 4G, 10G, and 18G. The inner coating was formed under the same conditions as in 1. About the obtained inner surface coating, hardness was measured like Example 1-4. The results are also shown in Table 3.
[0061]
[Table 3]

[0062]
As is apparent from the results in Table 3, Examples 1 to 4, which were centrifugally cast with a higher centrifugal force, had extremely higher surface hardness of the inner surface coating than the comparative example with a lower centrifugal force. Therefore, it was confirmed that the surface hardness of the inner surface coating can be increased by applying the present invention while using the same self-fluxing alloy. As a result of cutting the cross section of the inner surface coating formed in Example 2 and observing under a microscope, it has a three-layer structure as shown in FIG. 3, and the surface layer 21a has a structure in which the number of hard ceramic particles is extremely large. It was. This is considered to have greatly improved the hardness.
[0063]
[Examples 5 to 7]
(1) A cylindrical body 1 and self-fluxing alloy powder having the following specifications were prepared.

(2) Powder supply and powder layer formation
The cylindrical body 1 is set in the manufacturing apparatus shown in FIG. 5, and 2.5 kg of powder is charged in one place in the cylindrical body 1. Thereafter, both ends of the cylinder body G are closed by the

covers

15 and 15A, and then the cylinder body 1 is rotated at 70 rpm for 20 seconds. As a result, the powder is uniformly distributed in the axial direction in the cylindrical body 1.
Next, the rotation of the cylindrical body 1 is accelerated to a rotational speed at which a centrifugal force of 10 G acts on the inner peripheral surface, and is maintained at the rotational speed after reaching the rotational speed. The acceleration at this time was an acceleration reaching a centrifugal force from 0 to 3 G in 2 seconds.
[0064]
(3) Heat melting and solidification of powder
The cylinder body 1 is heated to 1050 ° C. Thereby, the temperature of the internal powder is also raised to substantially the same temperature, and the powder is partially melted. After heating and raising the temperature of the cylindrical body 1 to 1050 ° C., the compressor 32 is operated and 0.3 MPa (Example 5), 0.6 MPa (Example 6), 1. Any atmospheric pressure of 0 MPa (Example 7) was applied and maintained at that temperature and atmospheric pressure for 15 seconds, after which only heating was stopped and the mixture was allowed to cool. Thereby, the molten metal layer of the inner surface of the cylinder body 1 was solidified, and an inner surface coating was formed on the inner peripheral surface of the cylinder body.
(4) Hardness measurement of inner coating
The resulting inner coating was 2 mm thick. The hardness of the inner surface coating at a depth of 0.5 mm, 1.0 mm and 1.5 mm was measured. The results are shown in Table 4.
[0065]
[Comparative Example 4]
The inner surface coating was applied under the same conditions as in Example 5 except that the cylinder body 1 and self-fluxing alloy powder having the same specifications as in Example 5 were used, and the pressure applied to the cylinder body 1 during heating and melting of the powder layer was set to 0. Formed. About the obtained inner surface coating, hardness was measured like Example 5-7. The results are also shown in Table 4.
[0066]
[Table 4]

[0067]
As is apparent from the results in Table 4, Examples 5 to 7, which were centrifugally cast by applying an atmospheric pressure of 0.3 MPa or more to the molten metal layer in the cylindrical body 1, were compared with Comparative Example 4 in which no atmospheric pressure was applied. The hardness was large. Therefore, it was confirmed that the surface hardness of the inner surface coating can be increased by applying the present invention while using the same self-fluxing alloy.
[0068]
[Example 8]
The cylindrical body 1 and self-fluxing alloy powder having the same specifications as those in Example 2 were used, and this cylindrical body 1 was set in the manufacturing apparatus shown in FIG. 5 and applied to the inner peripheral surface of the cylindrical body 1 when the powder layer was heated and melted. An inner surface coating was formed under the same conditions as in Example 2 except that an atmospheric pressure of 1.0 MPa was applied (thus, under the condition that a centrifugal force of 34 G acts on the inner peripheral surface of the cylindrical body 1 during heating and melting). The hardness of the inner surface coating obtained was measured in the same manner as in Example 2. The results and the results of Example 2 are shown in Table 5.
[0069]
[Table 5]

[0070]
As is clear from the results in Table 5, the example 8 in which centrifugal force of 34 G was applied to the inner peripheral surface position of the cylinder body 1 and at the same time an atmospheric pressure of 1.0 MPa was applied to perform centrifugal casting does not apply atmospheric pressure. The hardness of the inner surface coating was further increased as compared with Example 2 performed in (1). Thus, it was confirmed that the hardness of the inner surface coating could be further increased by applying a high G centrifugal force to the molten metal layer and simultaneously applying a high atmospheric pressure.
[0071]
As a result of cutting the cross section of the inner surface coating formed in Example 8 and observing under a microscope, the surface layer 21a also has a very large amount of hard ceramic fine particles as shown in FIG. It was an organization. The chemical components of the surface layer 21a and the boundary layer 21c were measured, and the results shown in Table 6 were obtained. Table 6 also shows the chemical components of the self-fluxing alloy powder (Heganess # 1560) before the heat treatment. In addition, the component density | concentration in Table 6 is mass%.
[0072]
[Table 6]

[0073]
As is apparent from Table 6, the chromium concentration in the surface layer 21a is high, while the chromium concentration is low in the boundary layer 21c. This is because the fine particles of chromium compound-based hard ceramics deposited in the molten metal are accumulated in the surface layer by applying a high G centrifugal force during centrifugal casting.
[0074]
【The invention's effect】
As described above, the present invention sets a state in which a centrifugal force of 20 to 50 G acts on the inner peripheral surface position of the cylinder body when the inner surface coating with the self-fluxing alloy is formed on the inner peripheral surface of the cylinder body by centrifugal casting. Or, by adopting a configuration in which a pressure of 0.3 to 3 MPa is applied to the surface of the molten metal layer, the inner surface coating is made using the same self-fluxing alloy as compared with the inner surface coating formed by the conventional method. It has an effect that the surface hardness can be increased and an inner surface-coated cylinder excellent in wear resistance can be manufactured. In addition, the inner surface-coated cylinder manufactured according to the present invention has excellent wear resistance. By applying this to a resin molding machine cylinder, a steel pipe for slurry transportation, etc., it has excellent wear resistance and service life. Products such as long resin molding machine cylinders and steel pipes for slurry transportation can be obtained.
[Brief description of the drawings]
FIGS. 1A and 1B are schematic perspective views showing an apparatus for manufacturing an inner surface-covered cylinder according to an embodiment of the present invention in different operating states.
2 (a), (b), (c), and (d) are schematic cross-sectional views showing a procedure for forming a resin coating on the inner peripheral surface of a cylindrical body by the apparatus of FIG.
FIG. 3 is a schematic cross-sectional view showing the cross-sectional structure of the inner surface coating.
FIG. 4 is a schematic perspective view of an apparatus for manufacturing an inner surface-covered cylinder according to another embodiment of the present invention.
FIG. 5 is a schematic perspective view of an inner surface-coated cylinder manufacturing apparatus according to still another embodiment of the present invention.
FIG. 6 is a schematic perspective view of an apparatus for manufacturing an inner surface-covered cylinder according to still another embodiment of the present invention.
FIG. 7 is a graph showing the relationship between the surface roughness of the inner peripheral surface of the cylindrical body and the acceleration time with respect to the thickness deviation in the axial direction of the coating obtained in Experiment 1;
FIG. 8 is a graph showing the relationship between the cylindrical body inner diameter and the acceleration time with respect to the axial thickness deviation of the coating obtained in Experiment 2;
[Explanation of symbols]
1 Tube body
2 Self-fluxing alloy powder
3 Cylindrical support rotation device
4 Receiving roll
5 Presser roll
6 Variable speed motor
7 Control device
9 Powder feeder
10 Powder supply pipe
11 Hopper cart
13 Heating device
15,15A cover
20 Inner coated cylinder
21 Inner surface coating
25 Connecting pipe
26 Rotary joint
27 Piping
28,28A On-off valve
29 Vacuum pump
31 Pressure regulating valve
32 Compressor

Claims

In the method of manufacturing an inner surface-covered cylindrical body including a step of centrifugally casting and coating a self-fluxing alloy on the inner peripheral surface of a cylindrical body having a cylindrical inner peripheral surface, the centrifugal casting is performed at the position of the inner peripheral surface. By performing at a rotational speed at which a centrifugal force of ˜50 G is generated, fine particles having a specific gravity lower than that of the joint metal phase of the molten metal among the hard ceramic fine particles present in the melt of the self-fluxing alloy being cast are placed on the inner diameter side of the centrifugal casting system. A method for producing an inner surface-coated cylinder, wherein the inner surface coating in which the fine particles with low specific gravity are accumulated on the inner diameter side is obtained by anti-centrifugal accumulation and solidifying the molten metal in this state.

The inner surface-coated cylinder according to claim 1, wherein the fine particles having a specific gravity lower than that of the joint metal phase are fine particles of ceramics belonging to any one of chromium boride, carbide, and borocarbide precipitated from a molten alloy. Method.

The fine particles having a specific gravity lower than that of the joint metal phase are the fine particles of ceramics belonging to any one of chromium boride, carbide and borocarbide precipitated from the self-fluxing alloy melt, and the self-fluxing alloy in the self-fluxing alloy melt. The method for producing an inner surface-covered cylindrical body according to claim 1, which is a hard ceramic fine particle having a specific gravity of 7 or less, introduced as a component outside the basic composition.

In the method of manufacturing an inner surface-covered cylinder including a step of centrifugally casting and coating a self-fluxing alloy on the inner peripheral surface of a cylindrical main body having a cylindrical inner peripheral surface, the centrifugal casting is performed on the surface of the molten metal layer by 0.0. The manufacturing method of the inner surface covering cylinder characterized by performing in the state which acted the atmospheric | air pressure of 3-3 Mpa.

In the method of manufacturing an inner surface-covered cylinder including a step of centrifugally casting and coating a self-fluxing alloy on the inner peripheral surface of a cylindrical main body having a cylindrical inner peripheral surface, the centrifugal casting is performed on the surface of the molten metal layer by 0.0. In a state where the atmospheric pressure of 3 to 3 MPa is applied, and in the state where the atmospheric pressure is applied to the surface of the molten metal layer, the rotational speed of the cylindrical body is set to a centrifugal force of 10 G or more at the inner peripheral surface position. The manufacturing method of the inner surface covering cylinder characterized by setting it as the rotational speed which produces.

In the method of manufacturing an inner surface-covered cylinder including a step of centrifugally casting and coating a self-fluxing alloy on the inner peripheral surface of a cylindrical main body having a cylindrical inner peripheral surface, the centrifugal casting is performed on the surface of the molten metal layer by 0.0. In a state where the atmospheric pressure of 3 to 3 MPa is applied, and in the state where the atmospheric pressure is applied to the surface of the molten metal layer, the rotational speed of the cylindrical body is set to a centrifugal force of 20 to 50 G at the inner peripheral surface position. By setting the rotational speed at which force is generated, among the hard ceramic fine particles present in the melt of the self-fluxing alloy during casting, fine particles having a lower specific gravity than the joint metal phase of the molten metal are anti-centrifugally accumulated on the inner diameter side of the centrifugal casting system. In this state, the molten metal is solidified to obtain an inner surface coating in which the fine particles having a low specific gravity are accumulated on the inner diameter side.

The temperature reached by the self-fluxing alloy melt in the centrifugal casting is 70% from the solidus line side within the solid-liquid coexistence temperature from the solidus line to the liquidus temperature related to melting and solidification of the self-fluxing alloy. The method for producing an inner surface-covered cylindrical body according to any one of claims 1 to 6, wherein the temperature is not more than a positioned temperature.

In the centrifugal casting, the self-fluxing alloy molten metal layer is formed on the inner peripheral surface by introducing a self-fluxing alloy powder into the cylindrical body, and heating and melting the powder under rotation of the cylindrical body. The manufacturing method of the inner surface covering cylinder of any one of Claim 1 to 6 performed.

In the centrifugal casting, the self-fluxing alloy melt layer is formed on the inner peripheral surface. (1) A self-fluxing alloy powder in an amount corresponding to the coating formation thickness is placed inside the horizontally placed cylinder body. (2) The cylinder body is rotated by rotating the cylinder body around the axis, and reaches a rotational speed at which a centrifugal force of 3 G or more is generated at the inner peripheral surface position of the cylinder body. The powder in the main body is stretched over the inner peripheral surface of the cylinder body in a form that extends in the circumferential direction of the cylinder body. The following empirical formula (A) is used so as to suppress the movement of the powder arranged uniformly in the body axis direction in the cylinder axis direction.
τ (seconds) = 3 × 10 ⁵ / D ³ (A)
[D is the inner diameter of the cylinder (mm)]
By setting the value so as not to exceed the time τ required in step (b), a powder layer having almost no thickness deviation is formed in the axial direction and circumferential direction of the cylindrical body, and is stretched on the inner peripheral surface of the cylindrical body. 7. The method according to claim 1, wherein the main body is heated and the powder in the main body is melted at the same time so as to simultaneously raise the temperature of the entire main body while keeping the main body rotating. Manufacturing method of the inner surface-coated cylinder.

In the centrifugal casting, the self-fluxing alloy molten metal layer is formed on the inner peripheral surface by introducing a self-fluxing alloy powder into the cylindrical body, and heating and melting the powder under rotation of the cylindrical body. The method for producing an inner surface-covered cylindrical body according to any one of claims 1 to 6, wherein the powder in the cylindrical body is melted under reduced pressure.

In an inner surface coated cylinder in which an inner surface coating of a self-fluxing alloy is formed by centrifugal casting on the inner circumferential surface of a cylindrical body having a cylindrical inner circumferential surface, a chromium content concentration is 20 to 40 mass on the inner diameter side in the inner surface coating. An inner surface-covered cylindrical body characterized in that a hard layer having an increased hardness is formed by distributing fine particles of chromium compound hard ceramics at a high density up to a level of%.

The inner surface-coated cylinder according to claim 11, wherein a clean layer having a spectroscopic area ratio of non-metallic inclusions of 0.1% or less is formed on the outer diameter side in the inner surface coating.

A cylindrical body supporting and rotating device for horizontally supporting and rotating the cylindrical body, and supplying a self-fluxing alloy powder in an amount corresponding to the coating formation thickness into the cylindrical body supported by the cylindrical body supporting and rotating device. A powder supply device and a heating device that heats the entire length of the cylindrical body supported by the cylindrical body rotation support device are provided, and the cylindrical body support rotation device places the cylindrical body in the position of the inner circumferential surface of the cylindrical body. An apparatus for manufacturing an inner surface-coated cylinder, which can be rotated at a rotational speed at which a centrifugal force of 20 to 50G is generated.

A cylindrical body supporting and rotating device for horizontally supporting and rotating the cylindrical body, and supplying a self-fluxing alloy powder in an amount corresponding to the coating formation thickness into the cylindrical body supported by the cylindrical body supporting and rotating device. A powder supply device, a heating device that heats the entire length of the cylindrical body supported by the cylindrical rotation support device, and a pressurizing unit that applies an atmospheric pressure of 0.3 to 3 MPa to the inner surface of the cylindrical body. An apparatus for producing an inner surface-covered cylindrical body.

A cylindrical body supporting and rotating device for horizontally supporting and rotating the cylindrical body, and supplying a self-fluxing alloy powder in an amount corresponding to the coating formation thickness into the cylindrical body supported by the cylindrical body supporting and rotating device. A powder supply device, a heating device that heats the entire length of the cylindrical body supported by the cylindrical rotation support device, and a pressurizing unit that applies an atmospheric pressure of 0.3 to 3 MPa to the inner surface of the cylindrical body. And an apparatus for manufacturing an inner surface-covered cylindrical body, wherein the cylindrical body supporting rotating device is configured to rotate the cylindrical body at a rotational speed at which a centrifugal force of 10 G or more is generated at a position of an inner peripheral surface of the cylindrical body.

A cylindrical body supporting and rotating device for horizontally supporting and rotating the cylindrical body, and supplying a self-fluxing alloy powder in an amount corresponding to the coating formation thickness into the cylindrical body supported by the cylindrical body supporting and rotating device. A powder supply device, a heating device that heats the entire length of the cylindrical body supported by the cylindrical rotation support device, and a pressurizing unit that applies an atmospheric pressure of 0.3 to 3 MPa to the inner surface of the cylindrical body. The inner surface coating according to claim 14, wherein the cylindrical body supporting and rotating device is configured to rotate the cylindrical body at a rotational speed at which a centrifugal force of 20 to 50 G is generated at a position of an inner peripheral surface of the cylindrical body. Tube manufacturing equipment.

The said heating apparatus is provided with the inductor which induction-heats simultaneously the small section of the circumferential direction of the cylinder main body supported by the said cylinder rotation support apparatus over the cylinder full length. An apparatus for producing an inner surface-coated cylinder according to claim 1.