JP4345480B2

JP4345480B2 - Manufacturing apparatus and manufacturing method of laminated iron core

Info

Publication number: JP4345480B2
Application number: JP2003522113A
Authority: JP
Inventors: 一道佐志; ゆか小森; 正樹河野; 厚人本田
Original assignee: JFE Steel Corp
Current assignee: JFE Steel Corp
Priority date: 2001-08-17
Filing date: 2002-08-15
Publication date: 2009-10-14
Anticipated expiration: 2022-08-15
Also published as: JPWO2003017296A1; KR100526286B1; CN1307664C; TW595068B; KR20040072610A; CN1568528A; WO2003017296A1

Description

技術分野
本発明は回転機及び変圧器などに用いられる積層鉄心を製造する、製造装置および製造方法に関する。
背景技術
回転機や変圧器等の電気機器に使用される積層鉄心は、電磁鋼板を積層する、下記の工程により製造される。すなわち、積層後の渦電流を減少させるため、まず電磁鋼板に絶縁被膜を施し、その後前記電磁鋼板を打ち抜き加工又はせん断加工して、鉄心の断面形状を有する小片とし、前記小片を多数積み重ねて積層体とし、さらに溶接、カシメもしくは接着剤などを用いて、積層された小片を互いに固着せしめて製造されている。
しかしながら、溶接による固着方法では、鉄心のエッジ部が短絡されて絶縁性が低下するという問題や、熱歪により磁気特性が劣化するという問題があった。また、カシメによる固着方法でも、加工歪により磁気特性が悪化するという問題がある。一方、接着剤による固着方法では、上記のような磁気特性の劣化の問題は小さいが、鋼板１枚毎に接着剤を塗布する必要があり、作業性が悪いという問題があり、さらに、比較的鉄板との密着性の低い絶縁被膜が鋼板の表面にあって接着剤の下地となるため、鋼板と下地絶縁被覆が剥離しやすく、接着力が十分でないという問題もあった。
他方、特開平２−２０８０３４号公報では、ガラス転移温度６０℃以上の熱可塑性樹脂を電磁鋼板に塗布し、乾燥した後、該鋼板を所定形状に加工して積層し、２００〜３００℃程度に加熱および加圧して積層鉄心を製造する方法が開示されている。この方法には、鋼帯や板サイズの大きい大板の状態で樹脂被覆を行えるため鋼板（小片）１枚毎に接着剤を塗布する工程を省略でき、また固着に際して加工歪の影響を受けにくく、鋼帯をコイル状に巻いた場合においても板同士が接合するいわゆるブロッキングが発生しにくいという利点がある。しかしながら、寸法の大きな（例えばφ１００ｍｍ、厚み５０ｍｍ程度以上の）積層鉄心の場合、所定の温度に加熱するまでに必要な時間が非常に長くなり（例えば少なくとも６０分程度以上）、実用的に十分な接着を実現することは困難であった。
また、特開平１１−１８７６２６号公報では誘電体である接着被膜を加熱する高周波誘電加熱による短時間接着方法が開示されており、積層される板の寸法・形状は不明ながら、２０ｋｇ／ｃｍ^２（約２ＭＰａ）の加圧下で約５０ｍｍ厚の積層体を４分、約２５ｍｍ厚の積層体を２〜４分で加熱している。しかしながら、特開平１１−１８７６２６号公報に開示の方法では、装置が高価につくという問題があり、しかも印加電圧を放電電圧以下に抑えなければならないことから加熱時間をこれ以上短縮することが困難であるという問題があった。なお、高周波誘導加熱（周波数：数キロヘルツ〜数十キロヘルツ）による方法も考えられるが、装置が高価であるという問題や、均一な加熱が難しいという問題があった。
一方、特開平７−２９８５６７号公報には積層した鋼板を１０〜１００Ｈｚの周波数で誘導加熱しながら加圧し、その際に鋼板の加熱前の温度に基づいて誘導加熱時間を制御する技術が開示されており、積層体の寸法が不明ながら加熱時間約１１〜１２分のデータが示されている。しかし特開平７−２９８５６７号公報に記載の方法は、均一な加熱ができるものの、原理的に加熱効率が低いので、上記実例はさほど寸法の大きくない積層鉄心の場合と考えられる。したがって、この方法では寸法の大きな積層鉄心の場合は少なくとも６０分程度の加熱時間が必要と予測され、実用性には疑問があった。
また、特開平５−２５５６４５号公報には、Ｅ型の第１，第２鉄心を脚部対向形に突合せ、中央脚端面間に熱硬化性樹脂を接着剤とする被接着部材を挿入し、中央脚を囲む誘導コイルに商用周波数の電流を通電して中央脚間に磁束を形成することにより、被接着部材を加熱接着する技術が、２枚の板の接着を例に開示されている。しかし、被接着部材の厚みが変わると第１，第２鉄心の脚部間隔が変わって磁束が満足に形成されなくなるため、積層鉄心の如く積層枚数が多く、製造される鉄心の厚みの範囲が広い場合には、適用が困難である。なお、熱硬化性樹脂を用いた特開平５−２５５６４５号公報に開示の方法では、熱可塑性樹脂を用いた前記の技術と異なり、実質上加圧を要しないので、加圧条件に関する記載はない。
発明の開示
発明が解決しようとする課題
本発明の目的は、熱可塑性樹脂を塗布し乾燥した電磁鋼板（加熱接着型絶縁皮膜付き電磁鋼板）を使用した積層鉄心を、鉄心の寸法が大きい場合でも安価に短時間で均一に加熱接着製造できる、積層鉄心の製造装置および製造方法を提供することにある。
課題を解決するための手段
本発明者らは前記目的を達成すべく鋭意研究した結果、加熱接着型絶縁被膜付き電磁鋼板の積層体からなるワークを用い、誘導コイルによりワーク積層方向に適正周波数で励磁しながら当該ワークを加圧し、かつ磁気閉回路を構成するよう構成したヨークによって、ワーク積層方向に適正圧力で加圧することにより、ワークが大きい場合でも効率よく短時間で均一に加熱圧着しうることを見出し、本発明をなした。
すなわち本発明は、以下に記載の積層鉄心の製造装置および方法である。
（１）加熱接着型絶縁被膜付き電磁鋼板を積層してなるワークをその積層方向に励磁して誘導加熱する誘導コイルと、ワークの積層方向（すなわち押圧方向）に相互不干渉的に相対移動可能な第１，第２ヨーク部材で、前記ワークの積層方向両端部を押圧し、かつ、該押圧時に磁気閉回路を形成するヨークとを有することを特徴とする積層鉄心の製造装置。
ここで、前記ワークが積層方向に貫通する孔もしくは溝を有するワークであって、前記ワークの前記孔もしくは溝に挿入する芯鉄心を有することがとくに好ましい。また、前記装置が、前記ワークと前記各ヨーク材との間に、耐熱・耐圧（耐座屈性）の非金属素材から成る絶縁板を有し、かつ、前記絶縁板が、１．０Ｗ／ｍ・Ｋ以下の熱伝導率を有することが好ましい。さらに、前記装置が、積層板のずれを防止するガイドを有することが好ましい。
なお、磁気閉回路は、前記第１および第２のヨーク部材で構成することが好ましいが、他のヨーク材（補助ヨーク材）をさらに用いて複数のヨーク材により磁気閉回路を構成させてもよい。
（２）（１）に記載された積層鉄心の製造装置を用いて前記ワークの積層鋼板を加熱圧着するにあたり、前記誘導コイルの励磁周波数を１０〜１０００Ｈｚとし、かつ前記ヨークの押圧圧力を０．１ＭＰａ以上とすることを特徴とする積層鉄心の製造方法。
（３）前記励磁周波数および前記押圧圧力は、ワーク内磁束密度の積層方向成分が０．２Ｔ以上となるように設定することを特徴とする（２）記載の積層鉄心の製造方法。
上記（２）および（３）の製造方法において、前記ヨークに所定の押圧圧力（接着のための目標圧力）を付与し、その後、励磁による誘導加熱を前記ワークに加えるか、前記ヨークに、励磁により前記電磁鋼板が振動してずれることを防止する程度の押圧圧力を付与し、その後、励磁による誘導加熱を前記ワークに加え、その後、前記ヨークに所定の押圧圧力（接着のための目標圧力）を付与することの、いずれかが好ましい。
発明を実施するための最良の形態
本発明に係る積層鉄心の製造装置（本発明装置）は、例えば図１Ａから図１Ｃに示すように、加熱接着型絶縁被膜付き電磁鋼板を積層してなるワーク１をその積層方向に励磁して誘導加熱する誘導コイル２と、ワーク１の積層方向、すなわち図の上下方向に相互不干渉的に相対移動可能な第１，第２ヨーク部材５Ａ，５Ｂでワーク１の積層方向両端部を押圧し該押圧時に磁気閉回路を形成するヨーク５とを有する。誘導コイル２は交流電源３（図３に示す）により給電される。ヨーク５はプレス４で押されてワーク１を押圧するが、ヨーク部材５Ａおよび５Ｂは互いに対して相対移動すれば良いので、一方のヨーク部材を固定し、他方のヨーク部材のみをプレス４などで移動させても良い。ワーク１とヨーク５とは耐熱・耐圧の絶縁板６（例えばガラスクロス等からなる）で電気的に絶縁される。
被加熱・被圧着材であるワークは、加熱接着型絶縁被膜付き電磁鋼板（電気鉄板）を積層したままの未圧着のものである。積層される電磁鋼板は通常の市販品を使用でき、無方向性、一方向性、二方向性のいずれに属するものでもよく、その限りにおいて化学組成、板厚はとくに限定されない。好ましい電磁鋼板の特性値は方向性電磁鋼板の場合は鉄損Ｗ_{１７／５０}（周波数５０Ｈｚ、最大磁束密度１．７Ｔにおける値）が０．５〜２．０Ｗ／ｋｇ程度、磁束密度Ｂ_８（磁化力８００Ａ／ｍにおける値）が１．７〜２．０Ｔ程度、無方向性電磁鋼板の場合は鉄損Ｗ_{１５／５０}（周波数５０Ｈｚ、最大磁束密度１．５Ｔにおける値）が２．０〜１２．０Ｗ／ｋｇ程度、磁束密度Ｂ_５０（磁化力５０００Ａ／ｍにおける値）が１．６〜１．９Ｔ程度である。
なお、本発明は、電磁鋼板板厚が通常の厚み（０．０５〜１．０ｍｍ程度）範囲にあるワークに適用しうるが、なかでも溶接、カシメによる固着が難しくなる０．５ｍｍ程度以下の電磁鋼板を積層したワークにおいては、本発明の適用による格段の難度の低下効果が得られるので、本発明の方法の適用が好ましい。
通常、積層鉄心の使用時には、積層された電磁鋼板の沿層方向（鋼板面に平行な方向）に励磁され、また、積層鉄心の製造のための誘導加熱においても同様に沿層方向に励磁される（図２Ａ）。この励磁で生じる渦電流による、鉄心使用時のエネルギー損失を減少させるため、積層鉄心用電磁鋼板は板厚の比較的薄いものが用いられる。積層鉄心の高性能化に伴い板厚はさらに薄くされる傾向にあるが、この結果、積層鉄心の製造時には、沿層方向に励磁する通常の誘導加熱方式における加熱効率が低下する。そして、加熱効率を上げるためにさらなる高周波化が必要になるなど、加熱が難しくなる傾向にあった。
これに対し、本発明では、発想を転換させ、積層電磁鋼板を沿層方向にではなく積層方向（鋼板面に垂直な方向）に励磁する（図２Ｂ）。積層方向に励磁するので渦電流の発生面積が拡大し、加熱効率が増加するのでいかに板厚が薄くなっても安価な低周波にて十分に効率よく加熱することができる。
なお、励磁方向は積層方向に平行にとるのが理想であるが、積層装置の製作や積層板の設置に際しての誤差などにより実際には厳密な平行は得難い。そこで、実質上ワーク積層方向全域に亘って十分な加熱がなされるための条件を検討した。その結果によると、励磁方向の積層方向に対するずれの角度は５度以内とすることが好ましい。
誘導コイル２は、磁気閉回路のどの位置にあってもよいが、図１Ａ等に示されるように、ワーク１の積層方向がコイル軸方向に沿うようにして、ワーク１をコイル孔内に収容可能なものが、加熱効率や均熱性の観点から好ましい。
他の形態として、図１Ｆに示すように、ヨークの一部をコイル穴内に収容可能とすることもできる。この形態では、ワークのセッティング工程が複雑化しないという利点がある。
ヨーク５は、第１ヨーク部材５Ａおよび第２ヨーク部材５Ｂからなり、これらのいずれか一方または両方が相互不干渉的に、すなわちヨーク部材同士が（操業範囲では）邪魔し合うことなく移動し、ワーク１を積層方向両端から押圧するので、厚みの種々異なるワークに対しても、該ワークの積層鋼板同士が圧接されるに必要かつ十分な積層方向の圧力を付与することができる。
また、ヨーク５は、ワーク１を押圧している状態で磁気閉回路を形成するように構成されているので、ワーク１に十分な磁束を通すことができ、加熱効率が向上する。
第１ヨーク部材５Ａと第２ヨーク部材５Ｂとを相互不干渉的に移動させかつワーク押圧時に磁気閉回路を形成させるには、例えば図１Ａから図１Ｃに示すように、第１，第２ヨーク部材５Ａ，５Ｂの移動方向に沿う端面同士をスライド可能に突き合わせた構造とすればよい。
ここで、安定した強い磁気閉回路を形成するためには、両ヨーク部材の突き合わせ部のギャップＧは小さい方が望ましく、好ましくは５．０ｍｍ以下とする。また突き合わせ部の面積はなるべく広い方が良く、磁路を形成するヨークの断面積程度以上を確保することが好ましい。
図１Ａ〜図１Ｃのなかで、図１Ｂに示されるように、第１、第２ヨーク材のスライド可能に突き合わせた端面部分をそれぞれ突き出させて、突き合わせ部分の面積を確保した構造の方が、図１Ａおよび図１Ｃに示される、一方のヨーク材（図では第２のヨーク部材５Ｂ）の端面部分を突き出させた構造に比べて好ましい。この理由は、両ヨーク材の端面部分を突き出させた方が、ワーク厚みの変更によるヨーク部材の押圧位置の変動の影響を前記磁気閉回路が受けにくいからである。
なお、図１Ａに示されるように、一方のヨーク材の両端部を押圧方向に略平行に突き出させた構造が、対称形のヨークの中では最もヨークを小型化できる。
また、図１Ｃの構造は、プレス装置（プレス４）が小型でよいという利点を有する。
図１Ｄから図１Ｆには、本発明における、さらに別のヨークの形態を示す。
図１Ｄは、ヨーク側面側の突き合わせ部５１を例えばジョイント５２などで、ヨーク部材の本体５３と角度自在に結合させ、少なくとも退避位置（例えば５１’）から使用時の位置５１の間で移動できるようにした例である。この構造は、ワークのセッティングに際してヨークが干渉せず、しかも突き合わせ部におけるヨーク部材間のギャップを最小とすることができる。
図１Ｅは、上下のヨーク部材５Ａ、５Ｂのほかに、磁気閉回路を形成するための補助ヨーク材５Ｃを用いた例である。すなわち、補助ヨーク材５Ｃは退避位置（例えば５Ｃ’）と使用時の位置５Ｃの間で移動可能とし（移動装置は図示せず）、その結果図１Ｄと同様の利点を得ることができる。
また、図１Ｆは磁気閉回路を、図１Ａ等の用に３脚ではなく（ワークが１脚に相当する）、２脚のヨークで構成した例で、非対称の形状であるが、均一性に非常に敏感なワークでなければ問題なく使用可能である。図１Ｆの例では装置サイズが最小となる。なお、図１Ｆでは誘導コイル２の孔部がヨークを収納するよう設置した例を示したが、図１Ａなどで示されるように、ワーク１を収納するよう設置してもよい。
ヨークの形状などは、以上に述べた例に限定されるものではなく、例えば開示例の上下を逆にしたものや、ヨーク部材の左右の形態が非対称になるように開示例を組み合わせたものも、無論適用可能である。
なお、ヨークは、磁気回路構成部材として用いる観点から、鉄損の小さい材料すなわち方向性あるいは無方向性の電磁鋼板を積層し、相互に固着して形成するのが好ましい。ヨークに用いる電磁鋼板は、板厚が薄い方が、より好ましい。なお、このとき、該電磁鋼板はその易励磁方向（この例では板厚方向）に積層するのが好ましい。またこのとき、例えば図３に示すように、ヨーク５は、該ヨークをなす積層電磁鋼板の沿層方向が誘導コイル２による励磁方向にできるだけ平行となるように、組立・配置することが好ましい。こうすることにより、ヨークが誘導加熱されるのを可及的に抑制でき、電力の浪費やヨークの過昇温による損傷などを回避することができる。
絶縁材６は、非金属の絶縁材を用いる。ただし、絶縁材６はワークの押さえ板として機能する他、ワークとヨークとを電気的に絶縁してワークの誘導加熱を均一に安定化させる機能や、ワークからの熱の流出を防止してワーク内の均熱、ひいては接着の均一性を確保する役割を有する。したがって、絶縁材６の素材としては、絶縁性や加えられる加熱および加圧に耐えられるだけの耐熱性・耐圧性（とくに耐座屈性）を有すると共に、断熱性能が高いものが好ましい。使用条件に依るが、耐熱温度は２００〜８００℃程度、耐圧性としては左記温度下で０．５〜３００ＭＰａ程度の加圧に耐える程度の性能が好ましい。また、熱伝導率が１．０Ｗ／ｍ・Ｋ以下の、断熱性を有するものが好ましい。
上記の特性要求から、断熱材素材としては非金属の絶縁材が好ましいが、とくにガラス繊維やガラスクロス（ガラス繊維の織物）を主成分とし、シリコーン樹脂などの耐熱性樹脂等をバインダーとした素材が好適である。このような素材としては例えば、ロスナボード（ガラスクロス系；熱伝導率０．２４Ｗ／ｍ・Ｋ程度）が挙げられる。
なお、フッ素系樹脂やシリコーン樹脂も一般に耐熱性および断熱性は良好（熱伝導率が１．０Ｗ／ｍ・Ｋ以下）である。例えば前記特開平１１−１８７６２６号公報においては、絶縁材として厚み５ｍｍのテフロン登録商標シートあるいは厚み１０ｍｍのテフロン登録商標板を用いた例が開示されている。しかし、これらの樹脂は圧縮強度・座屈強度が低いので、ジート状にして単体で用いても、その適用効果は上記耐圧性素材に劣り不安定である。
他方、ワークの上下面にあたる電磁鋼板も通常は熱可塑性樹脂が塗布されているため、加熱・加圧により絶縁体とワークとが接着され、処理後にこれを引き剥がす工程が必要となることが多い。この場合、テフロン登録商標などは剥離性に優れているので、絶縁材６の表面層としてはフッ素系樹脂やシリコーン系樹脂を用いることも好適である。すなわち、上記ガラス繊維またはガラスクロス系の絶縁板に前記樹脂を表面被覆したり、あるいは上記ガラス繊維またはガラスクロス系の絶縁板の表層板としてテフロン登録商標シートやシリコーン樹脂シートなどの樹脂単体シートを使用したりすることが有効である。
なお、絶縁板の厚みは０．５ｍｍ以上、２０ｍｍ以下が好ましく、１．０ｍｍ以上、１０．０ｍｍ以下が更に好ましい。
なお、例えば図４Ａに示すように、積層方向に貫通する中心孔を有するワーク１に対しては該中心孔に芯鉄心７を挿入すると、磁束の整流効果が生まれ、より均一な励磁ができて好ましい。中心孔の代わりに、中心付近に到る積層方向に貫通する溝がある場合にも、同様に芯鉄心７の挿入が効果的である。
芯鉄心７は図４Ｂ、あるいは図４Ｃに示すように、ヨーク５と同様、方向性あるいは無方向性の電磁鋼板をその易励磁方向に積層し、沿層方向が誘導コイル２による励磁方向にできるだけ平行となるよう、相互に固着して形成したものが好ましい。ここで、図４Ｂは平面形状が略正六角形、図４Ｃは平面形状が略十字形の例であり、平面形状はこれらに限定されないが、複数の線対称軸を有する形状が、均一性確保の観点からは好ましい。
なお、ヨーク５あるいはさらに芯鉄心７は、繰り返し励磁による過加熱を防ぐため、水冷可能な構造とすることもできる。
なお、積層された電磁鋼板の位置を揃え、あるいは位置ずれを防止するために、ガイド８を設けても良い。ガイドの例を、図５Ａ、図５Ｂ、図６Ａおよび図６Ｂに、ワークおよびその周辺の断面図と平面図で例示する。
図５Ａおよび図５Ｂで示したガイド８は、略円筒形であり、ワークの前記中心孔などに挿入されてワークに内接し、これを内側より支える構造である。また、図５Ａおよび図５Ｂに示されるように、芯鉄心７を用いる（ここでは平面形状が略正十字形のものを例示した）場合に、ガイドが芯鉄心７に外接して芯鉄心を外側より支えるようにすることもできる。芯鉄心７はガイドに内接可能な形状であることが好ましいが、形状は任意であり、また芯鉄心７を省略することもむろん可能である。
図５Ｃ〜図５Ｆは、上記図５Ａおよび図５Ｂで示したガイド８の平面形状のバリエーションを示すための、絶縁材を図示しない平面図である。図５Ｃは単純な略円筒形のガイドの例であり、図ではガイド８がワーク１のティース部１０（後述）に内接してワーク１の位置決めを行う。
図５Ｄは、円筒形の外側に１個の突出部（キー９）を有する例で、ワークが中心孔側に複数の突出部（ティース部（ｔｅｅｔｈ）１０）を持つ形状の場合、とくに有効である。すなわち、ワーク１の位置がガイドの円筒部により前述のように位置決めされると共に、キー９がワーク１のティース部（ｔｅｅｔｈ）１０の間に挿入され、ティース部の位置決めを行い、ずれを防止する。図５Ｅはキー９を複数持つ形状であり、前記効果をより確実に達成する。
図５Ｆは６箇所に長めのキー９を有する構造で、キーの先端でワークに内接し、ワーク１およびそのティース部１０の位置決め・ずれ防止を行う。キー９でワークの位置決めを行う場合は、ガイド８を、最低２組の対向するキーを有する構造とすることが好ましい。
図６Ａおよび図６Ｂで示したガイド８も、略円筒形であるが、ワークに外接して、これを外側より支える構造である。本例においても芯鉄心７（平面形状が略円形のものを例示した）は省略可能であり、また芯鉄心７の形状は任意である。
図６Ｃ〜図６Ｅは、上記図６Ａおよび図６Ｂで示したガイド８の平面形状のバリエーションを示すための、絶縁材を図示しない平面図である。図６Ｃは単純な略円筒形のガイドの例であり、円筒内壁部でワーク１に内接し、ワーク１の位置決めを行う。図６Ｄは、円筒形の内側に３個の突出部（キー９）を有する例で、キー９でワーク１に外接し、３点支持によりワーク１の位置決めを行う。図６Ｅはキー９をさらに多数（図では６箇所）持つ形状であり、ワーク１の位置決めをより安定して行う。
なお、これらのガイドは、脱着の利便性のために、２つ以上の部材に分割可能とすることもできる。
図５Ａ〜図６Ｅに示したガイドは、いずれもガイドの上端が上側の絶縁板の上面と下面の間にあるよう高さが設計されているので、全ての積層板をガイドすることができると共に、ワークへの加圧時に加圧を受けることがなく、したがってワークへの加圧時にガイドを退避させる必要がない。
無論、実用上問題がなければ、積層方向の一部のみ、あるいは平面形状の一部のみを支えるガイドを採用しても良い。また、加圧に際してヨークと干渉するようなガイドであっても、加圧時に退避する構造としたり、加圧に耐え弾性変形する素材を用いたりすることで、使用可能である。
ガイド８の素材としては耐熱性を備えた素材、すなわち、ガラス繊維、ガラスクロス板、シリコーン樹脂、フッ素系樹脂などのエンジニアリングプラスチック、フェノール樹脂などの熱硬化性樹脂、およびこれらの複合材が好ましい。また、ワークを加圧する時にガイドにも加圧力が加わるような構造をやむを得ず選択し、かつ、加圧時にガイドを退避させたくない場合は、耐熱性及び弾性を備えた素材、すなわちシリコーン系ゴムなどをガイドの素材として用いることが好ましい。
次に、上記の本発明装置を用いて積層鉄心を製造する方法（本発明方法）における必須要件ないし好適要件について説明する。
まずワークを本発明の装置にセットする。このときのワーク（積層用電磁鋼板）、芯鉄心（使用する場合）、ガイド（使用する場合）をセットする順番は、状況に応じて行い易い順番で良い。
好適な方法としては、ワーク（積層用電磁鋼板）をガイドにセットしたものを用意し、芯鉄心と共に装置にセットする方法がある。この場合、加熱・加圧処理の終了後の手順としては、接着されたワーク（積層用電磁鋼板）をガイドと共にまず取出し、これを冷却後、ワークをガイドから分離させることが好ましい。
なお、芯鉄心はヨーク部材５Ａまたは５Ｂに固定されたものであることが、脱着作業の単純化の観点からは一般に好ましい。
本発明の方法では、誘導コイルによる励磁周波数は約１０〜約１０００Ｈｚとする必要がある。約１０Ｈｚ未満では十分な加熱ができない。他方、約１０００Ｈｚを超えると均一な加熱ができないため接着が不十分となり、あるいは十分な接着を達成するための均熱をとるのに時間がかかってしまう。なかでも商用周波数である約５０Ｈｚ及び約６０Ｈｚが、インバータ等の周波数変換器を使用せずとも簡単に得られる周波数なので、好適に用いられる。
また、ヨークによる押圧（加圧）圧力は約０．１ＭＰａ以上とする必要がある。約０．１ＭＰａ未満では十分な接着力が得られないばかりか、励磁による震動で積層鋼板がずれてしまう危険がある。
なお、押圧圧力を３００ＭＰａ超にすると鋼板が坐屈してしまう危険性があるので、好ましくは約０．１〜約３００ＭＰａである。また、接着力をさらに安定させる観点から、より好ましくは約０．５〜約５０ＭＰａである。なお、加圧継続時間は約１０秒以上とするのが好適である。
また、接着工程時間の短縮化の観点から、前記励磁周波数および前記押圧圧力は、ワーク内磁束密度の積層方向成分が約０．２Ｔ以上となるように設定することが好ましい。
なお、加圧及び誘導加熱の手順としては、目標圧力に加圧してから励磁（誘導加熱）を開始するようにしてもよい。また、加熱初期は励磁振動でずれない程度の低圧力（約０．１〜約０．５ＭＰａ程度）で加圧し、加熱が十分になってから（通常は加熱開始後約６０〜約６００秒程度）目標圧力に加圧するようにしてもよい。
ワークの加熱温度は、通常行われているように、加熱接着型絶縁被膜のガラス転移温度または軟化温度以上でかつ熱分解温度以下の範囲（加熱接着可能温度域）に設定するのが好適である。熱分解温度を超えない限度で、上記ガラス転移温度または軟化温度より約５０℃〜約１５０℃程度高い温度に加熱することが、とくに好ましい。
ワーク温度制御パターンとしては、加熱接着可能温度域への昇温のみでもよく、また昇温に温度保持を後続させたものでもよい。
ワークに用いる電磁鋼板に付与される熱可塑性樹脂、すなわちワークに係る加熱接着型絶縁被膜用樹脂（本発明用樹脂）は、特に限定されないが、アクリル系、エポキシ系、フェノール系、シリコーン系など、加熱により可塑性を示し、被膜同士が融着するものであればいずれも好ましく用いうる。また、２種以上の接着性樹脂の混合物であってもよく、さらに、アミン系硬化剤やシリカなどの添加物が、本発明の効果を損なわない程度に、含有されたものでもよい。
本発明用樹脂のガラス転移温度または軟化温度は、高い方が、良好な接着強度が得られ、かつ、当該樹脂塗布後の電磁鋼板鋼帯をコイル状に巻き取った場合においても鋼板同士のブロッキングをより抑制することができる。具体的には左記の観点から、本発明用樹脂のガラス転移温度または軟化温度は約６０℃以上であることが望ましい。
他方、誘導加熱の負荷を不必要に増大させないためには、本発明用樹脂のガラス転移温度または軟化温度は約２５０℃以下とすることが好ましい。
なお、被膜の性能を一層向上させるために、本発明用樹脂に防錆剤等添加剤を配合してもよい。この場合、歪取り焼鈍後の性能を確保する観点から、有機物質１００重量部に対する無機物質の合計量は約３〜約３００重量部の範囲とすることが好ましい。
ワークをなす積層された各電磁鋼板表面の熱可塑性樹脂の厚みは、特に限定されないが、約０．０５〜約２５μｍ程度が好ましく、さらに好ましくは約０．１〜約１０μｍである。この膜厚であれば、十分な層間抵抗があり、加熱・加圧による接着において十分な接着強度を発揮できる。
ワークとして積層される加熱接着型絶縁被膜付き電磁鋼板は、例えば次のような工程により製造される。すなわち、エマルジョン状態、ディスパージョン状態などの水系の接着性樹脂をロールコーター、フローコーター、スプレー塗装、ナイフコーター等種々の方法で電磁鋼板に塗布し、通常実施されるような熱風式、赤外式、誘導加熱式等の方法で焼付処理を行う。これら工程は切り板状の被処理材（電磁鋼板）に対して行ってもよいが、コイルコーティングにより電磁鋼板鋼帯に処理する方法が生産性が高く、より実用的である。
ワークの寸法はとくに限定しないが、従来短時間加熱の困難な、断面積約１，０００〜約１００，０００ｍｍ^２、厚み約５〜約５００ｍｍ程度の、比較的大型のワークへの適用に、とくに適する。
実施例
実施例１
アクリル系樹脂（組成：アクリル樹脂８５％、エポキシ樹脂１５％、軟化温度７０℃）が塗布焼付された板厚０．５ｍｍの加熱接着型絶縁被膜付き電気鉄板（電磁鋼板）を外径１００ｍｍ、内径５０ｍｍのリング状に打ち抜き、１００枚積層してなるワークを、図１Ａに示した形態の本発明装置に組み込み、表１に示す種々の条件で励磁および加圧してワーク内の電気鉄板同士を加熱接着する積層鉄心製造試験を行い、加熱時間と接着状態を調査した。
なお、絶縁板６として直径１１０ｍｍ、板厚５ｍｍのロスナボード（日光化成株式会社製；熱伝導率：０．２４Ｗ／ｍ・Ｋ）を用い、また、ガイド８として図５Ａ〜図５Ｃで示される形状のもの（素材：シリコーン樹脂）を用いた。また、加圧条件が１．０ＭＰａ未満の場合には、所定の圧力まで加圧後、誘導加熱を開始し、加圧条件が１．０ＭＰａ以上の場合は、０．２ＭＰａ加圧後に誘導加熱を開始し、加熱開始から１２０秒後に、所定の圧力まで加圧した。また、Ｎｏ．１０およびＮｏ．１１においては、本発明の磁気閉回路を形成する加圧ヨークを用いず、直接プレス機で加圧を行った。
ここで加熱時間は、ワーク側面に取り付けた熱電対による計測温度が室温から２００℃に到達するまでに要した時間で評価し、１時間以上経っても２００℃に到達しない場合は「到達せず」とした。接着状態は、加熱接着後の積層鉄心を強制的に剥離して剥離に必要な負荷を４段階に分けると共に、剥離で露出させた接着面の状態を目視により観察し、以下のように判定した。
◎；剥離負荷＝大、未接着部分＝ほとんど無し（未接着部面積率３０％未満）
○；剥離負荷＝中、未接着部分＝少なく存在（未接着部面積率３０％以上、６０％未満）
△；剥離負荷＝小、未接着部分＝中程度に存在（未接着部面積率６０％以上、９０％未満）
×；剥離負荷＝極微、未接着部分＝多く存在（未接着部面積率９０％以上）
結果を表１に示す。

同表に示されるように、本発明の方法に合致した実施例では、◎〜○の強固な接着状態が得られ、さらに励磁磁束０．２Ｔ以上の好適条件を満たした実施例では、２〜５０分の短い加熱時間で◎〜○の強固な接着状態が得られた。
また、とくに励磁周波数２０Ｈｚ以上かつ励磁磁束０．３Ｔ以上の条件では３０分以下、励磁周波数２０Ｈｚ以上かつ励磁磁束０．４Ｔ以上の条件では２０分以下、励磁周波数２０Ｈｚ以上かつ励磁磁束０．５Ｔ以上の条件では１０分以下と、より短い加熱時間で良好な接着が可能であり、さらに、励磁周波数４０Ｈｚ以上かつ励磁磁束０．７Ｔ以上の条件では４分以下、励磁周波数５０Ｈｚ以上かつ励磁磁束１．０Ｔ以上の条件では３分以下という極めて短い時間で良好な接着が可能であった。
実施例２
実施例１と同様のワークを、図１Ｂに示した形態の本発明装置に組みこみ、表２に示す種々の条件で励磁および加圧してワーク内の電気鉄板同士を加熱接着する積層鉄心製造試験を行い、加熱時間と接着状態を調査するとともに、実施例１と同様の方法により接着状態も判定した。なお、絶縁板６およびガイド８は、特記された例を除き、実施例１と同じものを用いた。また、芯鉄心としては厚み０．５ｍｍの電磁鋼板を図４Ｃの形状に積層し（幅広材３３ｍｍ×１００ｍｍ、積層枚数４０枚；幅狭材２０ｍｍ×１００ｍｍ、積層枚数前後各１３枚）固定したものを用い、前記ワークの中心孔に、図４Ａおよび図４Ｃに示す向きに挿入した。
結果を表２に示す。

同表に示されるように、本発明の方法に合致した実施例では、◎〜○の強固な接着状態が得られ、とくに芯鉄心を用いると、加熱時間がほぼ半減するという、顕著な効果が得られた。
一方、本発明の方法においてガイドを省略した場合、僅かながら加熱時間および接着状態でガイドを使用した場合より劣った。またワークの中心孔に挿入されてワークに内接する型のガイドの方が、ワークに外接する型より、効果が大であった。
また本発明の方法において、絶縁体として熱伝導率が１．０Ｗ／ｍ・Ｋを超えるものを用いた場合、好ましい絶縁体を用いた場合に比べると加熱時間が増加した。またテフロン登録商標シート単体を絶縁体とした場合も、耐圧性不足により、加熱時間が若干増加するとともに、変形により絶縁板の使用可能回数が低下した。他方、テフロン登録商標シートをロスナボードの表層板として用いたＮｏ．４４およびＮｏ．４５は、ロスナボード単体で用いた場合と同様の効果が得られた上、絶縁体とワークとの剥離が簡単で、作業性が向上した。
産業上の利用の可能性
かくして本発明によれば、加熱接着型電磁鋼板を使用した積層鉄心を、小さいものから大きいものまで安価に短時間で均一強固に加熱接着製造できるようになるという優れた効果を奏する。
【図面の簡単な説明】
図１Ａは、本発明装置の例を示す断面図である。
図１Ｂは、本発明装置の他の例を示す断面図である。
図１Ｃは、本発明装置のさらに他の例を示す断面図である。
図１Ｄは、本発明装置のさらに他の例を示す断面図である。
図１Ｅは、本発明装置のさらに他の例を示す断面図である。
図１Ｆは、本発明装置のさらに他の例を示す断面図である。
図２Ａは、積層電磁鋼板に対する、積層鉄心の通常使用時の励磁方向を示す立体図である。
図２Ｂは、積層電磁鋼板に対する、本発明でのワーク処理時の励磁方向を示す立体図である。
図３は、ヨークの好適例を示す立体図である。
図４Ａは、芯鉄心を用いた本発明装置の例を示す断面図である。
図４Ｂは、芯鉄心の好適例を示す立体図である。
図４Ｃは、芯鉄心の別の好適例を示す立体図である。
図５Ａは、ガイドを用いた本発明装置の例のワークまわりを示す断面図である。
図５Ｂは、図５Ａの例のワークまわりを示す平面図である。
図５Ｃは、図５Ａに用いるガイドの形状の一例を示す平面図（絶縁板を取り除いた状態）である。
図５Ｄは、図５Ａに用いるガイドの形状の別の一例を示す平面図（絶縁板を取り除いた状態）である。
図５Ｅは、図５Ａに用いるガイドの形状のさらに別の一例を示す平面図（絶縁板を取り除いた状態）である。
図５Ｆは、図５Ａに用いるガイドの形状のまたさらに別の一例を示す平面図（絶縁板を取り除いた状態）である。
図６Ａは、ガイドを用いた本発明装置の他の例のワークまわりを示す断面図である。
図６Ｂは、図６Ａの例のワークまわりを示す平面図である。
図６Ｃは、図６Ａに用いるガイドの形状の一例を示す平面図（絶縁板を取り除いた状態）である。
図６Ｄは、図６Ａに用いるガイドの形状の別の一例を示す平面図（絶縁板を取り除いた状態）である。
図６Ｅは、図６Ａに用いるガイドの形状のさらに別の一例を示す平面図（絶縁板を取り除いた状態）である。Technical field
The present invention relates to a manufacturing apparatus and a manufacturing method for manufacturing a laminated iron core used for a rotating machine, a transformer, and the like.
Background art
Laminated iron cores used in electrical equipment such as rotating machines and transformers are manufactured by the following process of laminating electromagnetic steel sheets. That is, in order to reduce the eddy current after lamination, an insulating coating is first applied to the electromagnetic steel sheet, and then the electromagnetic steel sheet is punched or sheared into small pieces having a cross-sectional shape of an iron core, and a large number of the small pieces are stacked and stacked. It is manufactured by bonding the stacked pieces to each other by using welding, caulking, or an adhesive.
However, the fixing method by welding has a problem that the edge portion of the iron core is short-circuited, resulting in a decrease in insulation, and a problem that magnetic characteristics are deteriorated due to thermal strain. In addition, even with the caulking fixing method, there is a problem that the magnetic characteristics are deteriorated due to processing strain. On the other hand, in the fixing method using an adhesive, the problem of deterioration of the magnetic properties as described above is small, but it is necessary to apply the adhesive to each steel sheet, and there is a problem that workability is poor. Since the insulating coating having low adhesion to the iron plate is on the surface of the steel sheet and serves as the base of the adhesive, there is also a problem that the steel sheet and the base insulating coating are easily peeled off and the adhesive force is not sufficient.
On the other hand, in Japanese Patent Application Laid-Open No. 2-208034, a thermoplastic resin having a glass transition temperature of 60 ° C. or higher is applied to a magnetic steel sheet and dried, and then the steel sheet is processed into a predetermined shape and laminated to about 200 to 300 ° C. A method of manufacturing a laminated iron core by heating and pressurizing is disclosed. In this method, since the resin coating can be performed in the state of a steel strip or a large plate having a large plate size, the step of applying an adhesive for each steel plate (small piece) can be omitted, and it is difficult to be affected by processing strain during fixing. Even when the steel strip is wound in a coil shape, there is an advantage that so-called blocking in which the plates are joined to each other hardly occurs. However, in the case of a laminated iron core having a large size (for example, φ100 mm, thickness of about 50 mm or more), the time required for heating to a predetermined temperature becomes very long (for example, at least about 60 minutes or more), which is practically sufficient. It was difficult to achieve adhesion.
Japanese Patent Application Laid-Open No. 11-187626 discloses a short-time bonding method by high-frequency dielectric heating that heats a dielectric adhesive film, and the dimensions and shape of the laminated plates are unknown, but 20 kg / cm. ² Under a pressure of (about 2 MPa), a laminate having a thickness of about 50 mm is heated for 4 minutes, and a laminate having a thickness of about 25 mm is heated for 2 to 4 minutes. However, the method disclosed in Japanese Patent Application Laid-Open No. 11-187626 has a problem that the apparatus is expensive, and it is difficult to further reduce the heating time because the applied voltage must be kept below the discharge voltage. There was a problem that there was. Although a method using high frequency induction heating (frequency: several kilohertz to several tens of kilohertz) is also conceivable, there are problems that the apparatus is expensive and that uniform heating is difficult.
On the other hand, Japanese Patent Application Laid-Open No. 7-298567 discloses a technique of pressurizing a laminated steel sheet with induction heating at a frequency of 10 to 100 Hz and controlling the induction heating time based on the temperature before heating the steel sheet. The data of the heating time of about 11 to 12 minutes is shown although the dimensions of the laminate are unknown. However, although the method described in Japanese Patent Application Laid-Open No. 7-298567 can perform uniform heating, the heating efficiency is low in principle. Therefore, the above example is considered to be a case of a laminated core having a relatively small size. Therefore, in this method, it is predicted that a heating time of at least about 60 minutes is required in the case of a laminated iron core having a large size, and there has been a question of practicality.
Further, in JP-A-5-255645, the E-type first and second iron cores are butted against the leg-facing shape, and a member to be bonded using a thermosetting resin as an adhesive is inserted between the center leg end faces, A technique for heating and bonding a member to be bonded by applying a current at a commercial frequency to an induction coil surrounding the central leg to form a magnetic flux between the central legs is disclosed as an example of bonding two plates. However, if the thickness of the bonded member changes, the leg interval of the first and second iron cores changes and the magnetic flux is not formed satisfactorily. If it is wide, it is difficult to apply. In the method disclosed in Japanese Patent Application Laid-Open No. 5-255645 using a thermosetting resin, unlike the technique using a thermoplastic resin, no pressure is required. .
Disclosure of the invention
Problems to be solved by the invention
The purpose of the present invention is to manufacture laminated iron cores using magnetic steel sheets coated with thermoplastic resin and dried (electrical steel sheets with heat-bonding type insulation coating) evenly and in a short time even when the core size is large. An object of the present invention is to provide a manufacturing apparatus and a manufacturing method for a laminated core.
Means for solving the problem
As a result of diligent research to achieve the above object, the present inventors have used a workpiece made of a laminated body of electromagnetic steel sheets with a heat-bonding type insulating coating, and applied the workpiece while exciting the workpiece at an appropriate frequency in the workpiece lamination direction by an induction coil. It is found that by pressing with an appropriate pressure in the workpiece stacking direction by a yoke configured to form a magnetic closed circuit, it is possible to perform heat and pressure bonding uniformly and efficiently in a short time even when the workpiece is large. I did it.
That is, this invention is the manufacturing apparatus and method of a laminated core as described below.
(1) Relative movement is possible in an incoherent manner in the laminating direction (ie, the pressing direction) of the induction coil that inducts and heats the work formed by laminating electromagnetic steel sheets with heat-bonding type insulation coating in the laminating direction. An apparatus for manufacturing a laminated iron core, comprising: a first yoke member that presses both end portions in the stacking direction of the workpieces, and a yoke that forms a magnetic closed circuit when the workpiece is pressed.
Here, it is particularly preferable that the workpiece has a hole or groove penetrating in the stacking direction, and has a core core inserted into the hole or groove of the workpiece. Further, the apparatus has an insulating plate made of a non-metallic material having heat resistance and pressure resistance (buckling resistance) between the workpiece and each yoke material, and the insulating plate is 1.0 W / It preferably has a thermal conductivity of m · K or less. Furthermore, it is preferable that the apparatus has a guide for preventing the deviation of the laminated plate.
The magnetic closed circuit is preferably configured by the first and second yoke members, but the magnetic closed circuit may be configured by a plurality of yoke materials by further using another yoke material (auxiliary yoke material). Good.
(2) When the laminated steel sheet manufacturing apparatus described in (1) is used for thermocompression bonding of the laminated steel plate of the workpiece, the excitation frequency of the induction coil is set to 10 to 1000 Hz, and the pressing pressure of the yoke is set to 0.1. The manufacturing method of the laminated iron core characterized by setting it as 1 Mpa or more.
(3) The method for manufacturing a laminated core according to (2), wherein the excitation frequency and the pressing pressure are set so that a lamination direction component of the magnetic flux density in the workpiece is 0.2 T or more.
In the manufacturing methods of (2) and (3) above, a predetermined pressing pressure (target pressure for adhesion) is applied to the yoke, and then induction heating by excitation is applied to the workpiece, or excitation is applied to the yoke. Is applied with a pressing pressure to prevent the electromagnetic steel plate from vibrating and slipping, and then induction heating by excitation is applied to the workpiece, and then a predetermined pressing pressure (target pressure for bonding) is applied to the yoke. Is preferred.
BEST MODE FOR CARRYING OUT THE INVENTION
As shown in FIGS. 1A to 1C, for example, the laminated iron core manufacturing apparatus (the present invention apparatus) according to the present invention excites a work 1 formed by laminating electromagnetic steel sheets with a heat-bonding insulating coating in the laminating direction. The induction coil 2 that performs induction heating and the first and

second yoke members

5A and 5B that can move relative to each other in the stacking direction of the work 1, that is, the vertical direction in the figure, press both ends of the work 1 in the stacking direction. And a yoke 5 that forms a magnetic closed circuit when pressed. The induction coil 2 is fed by an AC power source 3 (shown in FIG. 3). The yoke 5 is pressed by the press 4 and presses the work 1. However, the

yoke members

5A and 5B only have to move relative to each other, so one yoke member is fixed and only the other yoke member is pressed by the press 4 or the like. It may be moved. The work 1 and the yoke 5 are electrically insulated from each other by a heat-resistant / pressure-resistant insulating plate 6 (for example, made of glass cloth or the like).
The workpiece, which is the material to be heated / bonded, is an unpressurized one with the heat-bonded insulating coating-coated electromagnetic steel sheet (electric iron plate) being laminated. As the laminated electrical steel sheets, ordinary commercial products can be used, which may belong to any one of non-directional, unidirectional and bi-directional, and the chemical composition and thickness are not particularly limited as long as they are used. The characteristic value of preferred electrical steel sheet is iron loss W in the case of grain oriented electrical steel sheet. _17/50 (Value at 50 Hz, maximum magnetic flux density 1.7 T) is about 0.5 to 2.0 W / kg, magnetic flux density B ₈ In the case of a non-oriented electrical steel sheet (value at a magnetizing force of 800 A / m) is about 1.7 to 2.0 T, iron loss W _15/50 (Value at a frequency of 50 Hz and a maximum magnetic flux density of 1.5 T) is about 2.0 to 12.0 W / kg, magnetic flux density B ₅₀ (Value at a magnetizing force of 5000 A / m) is about 1.6 to 1.9 T.
In addition, although this invention can be applied to the workpiece | work which an electromagnetic steel plate board thickness exists in normal thickness (about 0.05-1.0 mm) range, about 0.5 mm or less which becomes difficult to adhere | attach by welding and crimping especially. The work of the present invention is preferably applied to a work in which electromagnetic steel sheets are laminated because the effect of reducing the degree of difficulty by application of the present invention can be obtained.
Normally, when using a laminated iron core, it is excited in the creeping direction of the laminated electrical steel sheets (direction parallel to the steel sheet surface), and in the induction heating for manufacturing the laminated iron core, it is excited similarly in the creeping direction. (FIG. 2A). In order to reduce energy loss when using the iron core due to the eddy current generated by this excitation, a laminated iron core electrical steel sheet having a relatively thin plate thickness is used. The plate thickness tends to be further reduced as the performance of the laminated core increases. As a result, the heating efficiency in the normal induction heating method in which excitation is performed in the laminating direction is lowered during the production of the laminated core. And in order to raise heating efficiency, there existed a tendency for the heating to become difficult, for example, the further high frequency was needed.
On the other hand, in the present invention, the idea is changed, and the laminated electromagnetic steel sheet is excited in the lamination direction (direction perpendicular to the steel sheet surface) instead of in the creeping direction (FIG. 2B). Since excitation is performed in the laminating direction, the generation area of eddy current is expanded and the heating efficiency is increased. Therefore, even if the plate thickness is reduced, it can be heated sufficiently efficiently at an inexpensive low frequency.
Ideally, the excitation direction should be parallel to the laminating direction. However, in reality, it is difficult to obtain strict parallelism due to errors in manufacturing the laminating apparatus and installing the laminated plate. Therefore, the conditions for sufficient heating over the entire work stacking direction were studied. According to the result, the angle of deviation of the excitation direction with respect to the stacking direction is preferably within 5 degrees.
The induction coil 2 may be in any position of the magnetic closed circuit, but as shown in FIG. 1A and the like, the work 1 is accommodated in the coil hole so that the stacking direction of the work 1 is along the coil axis direction. What is possible is preferable from the viewpoint of heating efficiency and soaking.
As another form, as shown in FIG. 1F, a part of the yoke can be accommodated in the coil hole. This form has the advantage that the workpiece setting process is not complicated.
The yoke 5 is composed of a first yoke member 5A and a second yoke member 5B, and either or both of them move in a mutually incoherent manner, that is, the yoke members move without interfering with each other (in the operation range) Since the workpiece 1 is pressed from both ends in the laminating direction, a necessary and sufficient pressure in the laminating direction can be applied to workpieces having different thicknesses so that the laminated steel plates of the workpiece are pressed against each other.
Further, since the yoke 5 is configured to form a magnetic closed circuit while the workpiece 1 is being pressed, a sufficient magnetic flux can be passed through the workpiece 1 and heating efficiency is improved.
In order to move the first yoke member 5A and the second yoke member 5B in a mutually incoherent manner and form a magnetic closed circuit when the workpiece is pressed, for example, as shown in FIGS. 1A to 1C, the first and second yokes What is necessary is just to make it the structure which faced end surfaces along the moving direction of

member

5A, 5B so that sliding was possible.
Here, in order to form a stable and strong magnetic closed circuit, it is desirable that the gap G between the abutting portions of both yoke members is small, and preferably 5.0 mm or less. Further, the area of the abutting portion should be as large as possible, and it is preferable to secure at least the cross-sectional area of the yoke forming the magnetic path.
1A to 1C, as shown in FIG. 1B, the structure in which the end surface portions of the first and second yoke members that are slidably butted are projected to secure the area of the butted portion, It is preferable compared to the structure shown in FIGS. 1A and 1C in which the end surface portion of one yoke member (second yoke member 5B in the drawing) is protruded. This is because the magnetic closed circuit is less susceptible to the influence of the change in the pressing position of the yoke member due to the change in the workpiece thickness when the end surfaces of both yoke members are protruded.
As shown in FIG. 1A, the structure in which both end portions of one yoke member protrude substantially parallel to the pressing direction can make the yoke most compact among symmetric yokes.
Moreover, the structure of FIG. 1C has an advantage that the press device (press 4) may be small.
1D to 1F show still another yoke configuration according to the present invention.
In FIG. 1D, the abutting portion 51 on the side surface of the yoke is coupled to the main body 53 of the yoke member at an angle with a joint 52, for example, so that it can move at least from a retracted position (for example, 51 ′) to a position 51 in use. This is an example. With this structure, the yoke does not interfere when the workpiece is set, and the gap between the yoke members at the abutting portion can be minimized.
FIG. 1E shows an example in which an auxiliary yoke material 5C for forming a magnetic closed circuit is used in addition to the upper and

lower yoke members

5A and 5B. That is, the auxiliary yoke material 5C can be moved between a retracted position (for example, 5C ′) and a position 5C in use (a moving device is not shown), and as a result, the same advantages as in FIG. 1D can be obtained.
FIG. 1F shows an example in which the magnetic closed circuit is configured with two yokes instead of three legs (the work corresponds to one leg) for the case of FIG. 1A and the like. Unless it is a very sensitive work, it can be used without problems. In the example of FIG. 1F, the apparatus size is minimized. In FIG. 1F, the example in which the hole of the induction coil 2 is installed so as to accommodate the yoke is shown. However, as shown in FIG.
The shape of the yoke is not limited to the example described above. For example, the disclosed example may be upside down, or may be a combination of the disclosed examples so that the left and right forms of the yoke member are asymmetric. Of course, it is applicable.
The yoke is preferably formed by laminating a material having a small iron loss, that is, a directional or non-directional electrical steel sheet, and fixing them to each other from the viewpoint of use as a magnetic circuit constituent member. The electromagnetic steel sheet used for the yoke is more preferably thinner. At this time, the electrical steel sheets are preferably laminated in the easy excitation direction (in this example, the thickness direction). At this time, for example, as shown in FIG. 3, the yoke 5 is preferably assembled and arranged so that the layering direction of the laminated electromagnetic steel sheets forming the yoke is as parallel as possible to the exciting direction by the induction coil 2. By doing so, it is possible to suppress as much as possible the induction heating of the yoke, and it is possible to avoid waste of electric power and damage due to excessive heating of the yoke.
The insulating material 6 uses a non-metallic insulating material. However, the insulating material 6 functions as a work holding plate, electrically insulates the work and the yoke to stabilize the induction heating of the work uniformly, and prevents the heat from flowing out of the work. It has the role of ensuring the inner soaking and thus the uniformity of adhesion. Therefore, as the material of the insulating material 6, it is preferable to have insulating properties and heat resistance and pressure resistance (particularly buckling resistance) sufficient to withstand heating and pressurization applied, and also high heat insulation performance. Although it depends on the use conditions, the heat resistant temperature is preferably about 200 to 800 ° C., and the pressure resistance is preferably a performance that can withstand pressurization of about 0.5 to 300 MPa at the temperature shown on the left. Moreover, what has heat insulation whose heat conductivity is 1.0 W / m * K or less is preferable.
In view of the above characteristic requirements, non-metallic insulating materials are preferred as the heat insulating material, but in particular, a material mainly composed of glass fiber or glass cloth (glass fiber woven fabric) and a heat-resistant resin such as silicone resin as a binder. Is preferred. Examples of such a material include Rossna board (glass cloth type; thermal conductivity of about 0.24 W / m · K).
In addition, the fluorine resin and the silicone resin generally have good heat resistance and heat insulation (heat conductivity is 1.0 W / m · K or less). For example, Japanese Patent Laid-Open No. 11-187626 discloses an example using a Teflon registered trademark sheet having a thickness of 5 mm or a Teflon registered trademark plate having a thickness of 10 mm as an insulating material. However, since these resins have low compressive strength and buckling strength, even if they are used in the form of a jet, the application effect is inferior to that of the pressure-resistant material and is unstable.
On the other hand, since the electrical steel sheets corresponding to the upper and lower surfaces of the workpiece are usually coated with a thermoplastic resin, the insulator and the workpiece are often bonded by heating and pressing, and a process of peeling off the workpiece after processing is often required. . In this case, since the Teflon registered trademark has excellent peelability, it is also preferable to use a fluorine-based resin or a silicone-based resin as the surface layer of the insulating material 6. That is, the resin is surface-coated on the glass fiber or glass cloth insulating plate, or a single resin sheet such as a Teflon registered trademark sheet or a silicone resin sheet is used as a surface layer plate of the glass fiber or glass cloth insulating plate. It is effective to use.
The thickness of the insulating plate is preferably 0.5 mm or more and 20 mm or less, and more preferably 1.0 mm or more and 10.0 mm or less.
For example, as shown in FIG. 4A, when a core iron core 7 is inserted into the center hole for a work 1 having a center hole penetrating in the stacking direction, a magnetic flux rectifying effect is produced, and more uniform excitation can be achieved. preferable. In the case where there is a groove penetrating in the stacking direction reaching the vicinity of the center instead of the center hole, the insertion of the core core 7 is also effective.
As shown in FIG. 4B or 4C, the core iron core 7 is formed by laminating directional or non-directional electrical steel sheets in the easy excitation direction as in the yoke 5, and the creeping direction is as much as possible in the excitation direction by the induction coil 2. Those formed by being fixed to each other so as to be parallel to each other are preferable. Here, FIG. 4B is an example in which the planar shape is a substantially regular hexagon, and FIG. 4C is an example in which the planar shape is a substantially cross shape. The planar shape is not limited to these, but a shape having a plurality of line symmetry axes can ensure uniformity. It is preferable from the viewpoint.
The yoke 5 or the core iron core 7 can also have a water-coolable structure in order to prevent overheating due to repeated excitation.
Note that a guide 8 may be provided in order to align the positions of the laminated electrical steel sheets or to prevent displacement. An example of the guide is illustrated in FIGS. 5A, 5B, 6A, and 6B with a cross-sectional view and a plan view of the workpiece and its periphery.
The guide 8 shown in FIGS. 5A and 5B has a substantially cylindrical shape, and has a structure in which it is inserted into the center hole or the like of the work and inscribed in the work and supported from the inside. Further, as shown in FIGS. 5A and 5B, when the core iron core 7 is used (in this example, a plane shape having a substantially regular cross shape is illustrated), the guide circumscribes the core iron core 7 so that the core iron core is outside. It can also be supported more. The core iron core 7 preferably has a shape that can be inscribed in the guide, but the shape is arbitrary, and the core iron core 7 can be omitted.
5C to 5F are plan views (not shown) showing an insulating material for showing variations in the planar shape of the guide 8 shown in FIGS. 5A and 5B. FIG. 5C shows an example of a simple substantially cylindrical guide. In the figure, the guide 8 is inscribed in a tooth portion 10 (described later) of the workpiece 1 to position the workpiece 1.
FIG. 5D is an example having one protrusion (key 9) on the outside of the cylindrical shape, which is particularly effective when the work has a shape having a plurality of protrusions (teeth 10) on the center hole side. is there. That is, the position of the work 1 is positioned by the cylindrical portion of the guide as described above, and the key 9 is inserted between the teeth 10 of the work 1 to position the teeth and prevent deviation. . FIG. 5E shows a shape having a plurality of keys 9 and achieves the above-described effect more reliably.
FIG. 5F shows a structure having long keys 9 at six locations, in which the work is inscribed at the tip of the key to prevent the work 1 and its tooth portion 10 from being positioned and displaced. When positioning the workpiece with the key 9, it is preferable that the guide 8 has a structure having at least two pairs of opposing keys.
The guide 8 shown in FIGS. 6A and 6B is also substantially cylindrical, but has a structure that circumscribes the work and supports it from the outside. Also in this example, the core core 7 (which has a substantially circular planar shape) can be omitted, and the shape of the core core 7 is arbitrary.
6C to 6E are plan views (not shown) showing an insulating material for showing variations of the planar shape of the guide 8 shown in FIGS. 6A and 6B. FIG. 6C shows an example of a simple substantially cylindrical guide. The workpiece 1 is inscribed by the inner wall portion of the cylinder, and the workpiece 1 is positioned. FIG. 6D is an example having three projecting portions (keys 9) on the inner side of the cylinder, and circumscribes the work 1 with the key 9 to position the work 1 by supporting three points. FIG. 6E shows a shape having a larger number of keys 9 (six locations in the figure), and positioning of the workpiece 1 is performed more stably.
Note that these guides can be divided into two or more members for convenience of attachment and detachment.
Each of the guides shown in FIGS. 5A to 6E is designed so that the upper end of the guide is between the upper surface and the lower surface of the upper insulating plate, so that all the laminated plates can be guided. Therefore, there is no need to pressurize the workpiece, and therefore there is no need to retract the guide when the workpiece is pressurized.
Of course, if there is no problem in practice, a guide that supports only a part of the stacking direction or only a part of the planar shape may be employed. Further, even a guide that interferes with the yoke during pressurization can be used by adopting a structure that retracts during pressurization or by using a material that can withstand pressurization and elastically deform.
The material of the guide 8 is preferably a material having heat resistance, that is, a glass fiber, a glass cloth plate, an engineering plastic such as a silicone resin or a fluorine resin, a thermosetting resin such as a phenol resin, or a composite material thereof. In addition, if a structure is unavoidably selected to apply pressure to the guide when pressurizing the workpiece, and you do not want to retract the guide during pressurization, a material with heat resistance and elasticity, that is, silicone rubber, etc. Is preferably used as a guide material.
Next, the essential or preferred requirements in the method for manufacturing a laminated iron core (the method of the present invention) using the above-described device of the present invention will be described.
First, a workpiece is set in the apparatus of the present invention. The order of setting the workpiece (magnetic laminated steel sheet), the core core (when used), and the guide (when used) at this time may be an order that can be easily performed depending on the situation.
As a suitable method, there is a method in which a workpiece (laminate electromagnetic steel sheet) set in a guide is prepared and set in an apparatus together with a core core. In this case, as a procedure after the end of the heating / pressurizing process, it is preferable to first take out the bonded work (laminar electrical steel sheet) together with the guide, cool it, and then separate the work from the guide.
In addition, it is generally preferable that the core core is fixed to the

yoke member

5A or 5B from the viewpoint of simplifying the attaching / detaching operation.
In the method of the present invention, the excitation frequency by the induction coil needs to be about 10 to about 1000 Hz. Sufficient heating is not possible below about 10 Hz. On the other hand, when the frequency exceeds about 1000 Hz, uniform heating cannot be performed, so that the adhesion becomes insufficient, or it takes time to obtain a uniform temperature for achieving sufficient adhesion. Among them, commercial frequencies of about 50 Hz and about 60 Hz are preferably used because they are frequencies that can be easily obtained without using a frequency converter such as an inverter.
The pressing (pressurizing) pressure by the yoke needs to be about 0.1 MPa or more. If it is less than about 0.1 MPa, not only a sufficient adhesive force cannot be obtained, but there is a risk that the laminated steel sheet will be displaced due to vibration caused by excitation.
In addition, since there exists a danger that a steel plate will buckle when a pressing pressure exceeds 300 Mpa, Preferably it is about 0.1-300 Mpa. Further, from the viewpoint of further stabilizing the adhesive force, it is more preferably about 0.5 to about 50 MPa. The pressurization duration is preferably about 10 seconds or longer.
Further, from the viewpoint of shortening the bonding process time, the excitation frequency and the pressing pressure are preferably set so that the component in the stacking direction of the magnetic flux density in the workpiece is about 0.2 T or more.
In addition, as a procedure of pressurization and induction heating, excitation (induction heating) may be started after pressurizing to a target pressure. In the initial stage of heating, pressurization is performed at a low pressure (about 0.1 to about 0.5 MPa) that does not shift due to excitation vibration, and after heating is sufficient (usually about 60 to about 600 seconds after heating is started). ) You may make it pressurize to target pressure.
As usual, the heating temperature of the workpiece is preferably set to a range (temperature range where heat bonding is possible) that is not lower than the glass transition temperature or softening temperature of the heat bonding type insulating coating and not higher than the thermal decomposition temperature. . It is particularly preferable to heat to a temperature about 50 ° C. to about 150 ° C. higher than the glass transition temperature or softening temperature as long as the thermal decomposition temperature is not exceeded.
The workpiece temperature control pattern may be only the temperature rise to the temperature range where heat bonding is possible, or may be a temperature rise followed by temperature holding.
The thermoplastic resin imparted to the electrical steel sheet used for the workpiece, that is, the heat-bonding insulating coating resin (the resin for the present invention) related to the workpiece is not particularly limited, but is acrylic, epoxy-based, phenol-based, silicone-based, etc. Any material can be preferably used as long as it exhibits plasticity by heating and the coatings are fused. Moreover, the mixture of 2 or more types of adhesive resin may be sufficient, and further, additives, such as an amine type hardening | curing agent and a silica, may be contained to such an extent that the effect of this invention is not impaired.
The higher the glass transition temperature or softening temperature of the resin for use in the present invention, the better the adhesive strength is obtained, and even when the magnetic steel sheet steel strip after application of the resin is wound in a coil shape, blocking between the steel sheets Can be further suppressed. Specifically, from the viewpoint described on the left, the glass transition temperature or softening temperature of the resin for use in the present invention is desirably about 60 ° C. or higher.
On the other hand, in order not to unnecessarily increase the load of induction heating, the glass transition temperature or softening temperature of the resin for use in the present invention is preferably about 250 ° C. or lower.
In order to further improve the performance of the coating, additives such as a rust inhibitor may be added to the resin for the present invention. In this case, from the viewpoint of securing the performance after strain relief annealing, the total amount of the inorganic substance with respect to 100 parts by weight of the organic substance is preferably in the range of about 3 to about 300 parts by weight.
The thickness of the thermoplastic resin on the surface of each laminated electrical steel sheet forming the workpiece is not particularly limited, but is preferably about 0.05 to about 25 μm, more preferably about 0.1 to about 10 μm. With this film thickness, there is sufficient interlayer resistance, and sufficient adhesive strength can be exhibited in adhesion by heating and pressing.
A magnetic steel sheet with a heat-bonding insulating coating laminated as a workpiece is manufactured, for example, by the following process. In other words, water-based adhesive resins such as emulsion and dispersion are applied to electrical steel sheets by various methods such as roll coater, flow coater, spray coating, knife coater, etc. Then, baking is performed by a method such as induction heating. Although these steps may be performed on a cut plate-like material (electromagnetic steel sheet), a method of treating an electromagnetic steel sheet steel strip by coil coating has high productivity and is more practical.
The dimensions of the workpiece are not particularly limited, but the cross-sectional area of about 1,000 to about 100,000 mm, which has conventionally been difficult to heat for a short time. ² It is particularly suitable for application to a relatively large workpiece having a thickness of about 5 to about 500 mm.
Example
Example 1
An electric iron plate (electromagnetic steel plate) with a heat-bonding insulating coating having a thickness of 0.5 mm coated and baked with acrylic resin (composition: acrylic resin 85%, epoxy resin 15%, softening temperature 70 ° C.) has an outer diameter of 100 mm. A workpiece formed by punching into a 50 mm ring shape and laminating 100 sheets is incorporated into the apparatus of the present invention shown in FIG. 1A, and the electric iron plates in the workpiece are heated by excitation and pressurization under various conditions shown in Table 1. A laminated core manufacturing test was conducted, and the heating time and adhesion state were investigated.
Note that a Rossna board (made by Nikko Kasei Co., Ltd .; thermal conductivity: 0.24 W / m · K) having a diameter of 110 mm and a thickness of 5 mm is used as the insulating plate 6, and the shape shown in FIGS. 5A to 5C as the guide 8. (Material: silicone resin) was used. When the pressurization condition is less than 1.0 MPa, induction heating is started after pressurization to a predetermined pressure. When the pressurization condition is 1.0 MPa or more, induction heating is performed after 0.2 MPa pressurization. After 120 seconds from the start of heating, the pressure was increased to a predetermined pressure. No. 10 and no. In No. 11, pressurization was directly performed by a press without using the pressurization yoke forming the magnetic closed circuit of the present invention.
Here, the heating time is evaluated by the time required for the temperature measured by the thermocouple attached to the side surface of the workpiece to reach 200 ° C. from room temperature. " The adhesion state was determined as follows by forcibly peeling the laminated iron core after heat bonding and dividing the load necessary for peeling into four stages, and visually observing the state of the bonding surface exposed by peeling. .
◎; peeling load = large, non-adhered part = almost none (area ratio of non-adhered part is less than 30%)
○: peeling load = medium, unbonded part = existent (unbonded part area ratio 30% or more, less than 60%)
Δ: peeling load = small, non-adhered part = moderate (non-adhered part area ratio 60% or more, less than 90%)
X: Peeling load = extremely fine, non-bonded portion = existent (non-bonded portion area ratio 90% or more)
The results are shown in Table 1.

As shown in the table, in the examples consistent with the method of the present invention, a strong adhesion state of ◎ to ○ was obtained, and in the examples satisfying the preferable condition of excitation magnetic flux 0.2T or more, 2 to A strong adhesion state of A to B was obtained in a short heating time of 50 minutes.
In particular, when the excitation frequency is 20 Hz or more and the excitation magnetic flux is 0.3 T or more, 30 minutes or less, and when the excitation frequency is 20 Hz or more and the excitation magnetic flux is 0.4 T or more, the excitation frequency is 20 Hz or more and the excitation magnetic flux is 0.5 T or more. In the condition of 10 minutes or less, good adhesion is possible with a shorter heating time, and in the condition of excitation frequency 40 Hz or more and excitation magnetic flux 0.7 T or more, it is 4 minutes or less, excitation frequency 50 Hz or more and excitation magnetic flux 1. Good adhesion was possible in a very short time of 3 minutes or less under the condition of 0T or more.
Example 2
A laminated core manufacturing test in which the same workpiece as in Example 1 is incorporated in the apparatus of the present invention shown in FIG. 1B, and the electric iron plates in the workpiece are heated and bonded together by excitation and pressurization under various conditions shown in Table 2. The heating time and the adhesion state were investigated, and the adhesion state was also determined by the same method as in Example 1. The insulating plate 6 and the guide 8 were the same as those in Example 1 except for a specially noted example. In addition, as the core, 0.5 mm thick electromagnetic steel plates are laminated in the shape of FIG. 4C (wide material 33 mm × 100 mm, number of laminated sheets 40; narrow material 20 mm × 100 mm, 13 sheets before and after the number of laminated sheets) and fixed. Was inserted into the center hole of the workpiece in the direction shown in FIGS. 4A and 4C.
The results are shown in Table 2.

As shown in the table, in the examples consistent with the method of the present invention, a strong adhesion state of ◎ to ○ is obtained, and particularly when a core iron core is used, the heating time is almost halved. Obtained.
On the other hand, when the guide was omitted in the method of the present invention, it was slightly inferior to the case where the guide was used in the heating time and the adhesion state. In addition, the type of guide that is inserted into the center hole of the workpiece and inscribed in the workpiece has a greater effect than the type of the guide inscribed in the workpiece.
In the method of the present invention, when an insulator having a thermal conductivity exceeding 1.0 W / m · K is used, the heating time is increased as compared with the case where a preferable insulator is used. Also, when the Teflon registered trademark sheet alone was used as an insulator, the heating time slightly increased due to insufficient pressure resistance, and the number of usable insulating plates decreased due to deformation. On the other hand, a Teflon registered trademark sheet was used as a surface layer board for Rossna board. 44 and no. No. 45 has the same effect as the case of using the rossner board alone, and it is easy to peel off the insulator from the work, and the workability is improved.
Industrial applicability
Thus, according to the present invention, there is an excellent effect that a laminated iron core using a heat-bonded electromagnetic steel sheet can be uniformly and firmly heated and manufactured in a short time from a small to a large one.
[Brief description of the drawings]
FIG. 1A is a cross-sectional view showing an example of the device of the present invention.
FIG. 1B is a cross-sectional view showing another example of the device of the present invention.
FIG. 1C is a cross-sectional view showing still another example of the device of the present invention.
FIG. 1D is a cross-sectional view showing still another example of the device of the present invention.
FIG. 1E is a cross-sectional view showing still another example of the device of the present invention.
FIG. 1F is a cross-sectional view showing still another example of the device of the present invention.
FIG. 2A is a three-dimensional view showing an excitation direction during normal use of the laminated iron core with respect to the laminated electromagnetic steel sheet.
FIG. 2B is a three-dimensional view showing the excitation direction during workpiece processing according to the present invention for a laminated electrical steel sheet.
FIG. 3 is a three-dimensional view showing a preferred example of the yoke.
FIG. 4A is a cross-sectional view showing an example of the device of the present invention using a core core.
FIG. 4B is a three-dimensional view illustrating a preferred example of the core core.
FIG. 4C is a three-dimensional view showing another preferred example of the core core.
FIG. 5A is a cross-sectional view showing the periphery of a workpiece in an example of the device of the present invention using a guide.
FIG. 5B is a plan view showing the periphery of the workpiece in the example of FIG. 5A.
FIG. 5C is a plan view (a state where an insulating plate is removed) showing an example of the shape of the guide used in FIG. 5A.
FIG. 5D is a plan view (a state where an insulating plate is removed) showing another example of the shape of the guide used in FIG. 5A.
FIG. 5E is a plan view (a state in which an insulating plate is removed) showing still another example of the shape of the guide used in FIG. 5A.
FIG. 5F is a plan view (a state in which an insulating plate is removed) showing still another example of the shape of the guide used in FIG. 5A.
FIG. 6A is a cross-sectional view showing the periphery of a workpiece in another example of the device of the present invention using a guide.
FIG. 6B is a plan view showing the periphery of the workpiece in the example of FIG. 6A.
FIG. 6C is a plan view (a state where an insulating plate is removed) showing an example of the shape of the guide used in FIG. 6A.
FIG. 6D is a plan view (a state in which an insulating plate is removed) showing another example of the shape of the guide used in FIG. 6A.
FIG. 6E is a plan view (a state in which the insulating plate is removed) showing still another example of the shape of the guide used in FIG. 6A.

Claims

An induction coil that inductively heats a work formed by laminating electromagnetic steel sheets with a heat-bonding insulating coating in the laminating direction;
A yoke that presses both ends of the workpiece in the stacking direction with first and second yoke members that can move relative to each other in the stacking direction of the workpiece, and forms a magnetic closed circuit during the pressing. An apparatus for manufacturing a laminated iron core, comprising: a yoke.

2. The laminated core manufacturing apparatus according to claim 1, wherein the workpiece has a hole or a groove penetrating in a laminating direction, and has a core core inserted into the hole or groove of the workpiece.

An insulating plate made of a heat-resistant / pressure-resistant non-metallic material is provided between the workpiece and each yoke material, and the insulating plate is made of a material having a thermal conductivity of 1.0 W / m · K or less. The apparatus for manufacturing a laminated iron core according to claim 1 or 2, characterized in that:

The said yoke is a yoke which forms the said magnetic closed circuit by the said 1st, 2nd yoke member and at least 1 other yoke member at the time of the said press, The one of Claims 1-3 characterized by the above-mentioned. The manufacturing apparatus of the laminated core described in 1.

When heating and press-bonding the laminated steel sheet of the workpiece using the laminated iron core manufacturing apparatus according to any one of claims 1 to 4, the induction coil has an excitation frequency of 10 to 1000 Hz, and the pressing pressure of the yoke The manufacturing method of the laminated iron core characterized by making 0.1 MPa or more.

6. The method of manufacturing a laminated core according to claim 5, wherein the excitation frequency and the pressing pressure are set so that a lamination direction component of the magnetic flux density in the workpiece is 0.2 T or more.

The method of manufacturing a laminated core according to claim 5 or 6, wherein a predetermined pressing pressure is applied to the yoke, and then induction heating by excitation is applied to the workpiece.

A pressing pressure is applied to the yoke to prevent the electromagnetic steel plate from vibrating and being displaced due to excitation, and then induction heating by excitation is applied to the workpiece, and then a predetermined pressing pressure is applied to the yoke. The method for producing a laminated core according to claim 5 or 6, wherein