JP2004153867A - Radial anisotropic sintered magnet, its manufacturing method, and magnet rotor and motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radial anisotropic sintered magnet which has excellent magnetic properties without cracks or cracking at sintering or aging cooling even in such a form that the inner-outer diameter ratio is small. <P>SOLUTION: This radial anisotropic sintered magnet contains a section which is formed cylindrical and oriented in a direction inclined at an angle of 30°or larger relative to the radial direction, not less than 2% and not more than 50% of a magnet volume, and the residual section of the magnet volume is oriented in the radial direction or with its inclination to the radial direction at angle of 30°or smaller. <P>COPYRIGHT: (C)2004,JPO

Description

【００６５】
［実施例３］
コア断面積の６０％の面積を占める飽和磁束密度１８ｋＧの強磁性体（ＳＫ５：Ｆｅ鋼）をコア外周と同心円状に配置し、残りは非磁性体材で作成したコアを用い、その他は実施例１と同様にして作製した円筒磁石をモータに組み込み、モータ特性を測定した。
【００６６】
［実施例４］
実施例１と同じ成形機を用い、発生磁場を６ｋＯｅとし、他は実施例１の条件で磁石を作製し、モータに組み込みモータ特性を測定した。
【００６７】
［比較例１］
実施例１と同様の磁石粉を用い、図２に示される垂直磁場垂直成形装置を用い、コイルの発生磁界２０ｋＯｅで磁石粉充填深さ３０ｍｍとし、磁場中成形後の成形体を下方に移動させ、成形体の上に先ほどと同様に３０ｍｍ磁石粉を乗せ、磁場中成形後の磁石を実施例１と同様の条件で焼結時効を行い、φ３０ｍｍ×φ２５ｍｍ×Ｌ３０ｍｍの円筒磁石を得た。これをモータに組み込みモータ特性を測定した。
【００６８】
［比較例２］
非磁性体（非磁性超硬材ＷＣ−Ｎｉ−Ｃｏ）をコア材に用いた以外は、実施例１と同じ条件で磁石を作製し、モータに組み込みモータ特性を測定した。
【００６９】
［比較例３］
飽和磁束密度２ｋＧの強磁性体（磁性超硬材ＷＣ−Ｎｉ−Ｃｏ）コアを配置した成形機にて、他は実施例１と同じ条件で磁石を作製し、モータに組み込みモータ特性を測定した。
【００７０】
［実施例５］
図５に示すように、非磁性体（非磁性超硬材ＷＣ−Ｎｉ−Ｃｏ）をダイス内角度３０°の部分で２個対称になるように配置し（トータル６０°）、その他は比較例１と同様な条件で磁石を作製し、同様にモータ特性を測定した。
【００７１】
偏光顕微鏡観察により、ラジアル配向に対し、３０°以上傾いた部分の体積（配向乱れ体積）を算出し、表２に示す。また、これらの円筒磁石をそれぞれの条件で１００個製造した際の割れの数もあわせて記載する。
【００７２】
【表２】

【００７３】
表２より、実施例は大きな起電力が得られ、かつトルクリップルが小さく、クラックの発生がないためモータ用磁石として優れた特性を有する磁石の量産化に有効である。
【００７４】
また、実施例４の条件で作製した磁石を偏光顕微鏡観察した結果を図１３、１４、１５に示す。即ち、図１３、１４、１５は強磁性材をコアとして用いた水平磁場垂直成形装置により作製された磁石において、配向磁場方向に対し、３０°方向、６０°方向、９０°方向での磁石の配向の様子を示したもので、これらからわかるように本発明による円筒磁石では、配向磁場方向に対し６０°方向で初めてラジアル方向とのずれが３０°となり、これより３０体積％で３０°以上ずれていることがわかる。
【００７５】
［実施例６〜９、参考例１］
それぞれ純度９９．７重量％のＮｄ、Ｄｙ、Ｆｅ、Ｃｏ、Ｍ（ＭはＡｌ、Ｓｉ、Ｃｕ）と純度９９．５重量％のＢを用い、Ｎｄ_２９Ｄｙ_２．５Ｆｅ_６３．８Ｃｏ_３Ｂ_１Ａｌ_０．３Ｓｉ_０．３Ｃｕ_０．１の合金を真空溶解炉で溶解鋳造してインゴットを作製した。このインゴットをジョウクラッシャー及びブラウンミルで粗粉砕し、更に窒素気流中ジェットミル粉砕により平均粒径３．５μｍの微粉末を得た。この粉末を図１に示すような飽和磁束密度２０ｋＧの鉄製の強磁性体コアを配置した水平磁場垂直成形装置にて、コイルの発生磁場４ｋＯｅの磁場中において配向させた後、実施例６として、コイルを９０°回転させ、次いで同様に４ｋＯｅの磁場中において再び配向させ、１．０ｔ／ｃｍ^２の成形圧にて成形した。
【００７６】
実施例７としては、水平磁場垂直成形装置にてコイルの発生磁場４ｋＯｅの磁場中において配向させた後、ダイスとコア及びパンチを９０°回転させ、次いで同様に４ｋＯｅの磁場中において再び配向させ、１．０ｔ／ｃｍ^２の成形圧にて成形した以外は実施例６と同様に成形した。
【００７７】
実施例８としては、水平磁場垂直成形装置にてコイルの発生磁場４ｋＯｅの磁場中において配向させた後、残留磁化４ｋＧのコアを９０°回転させた。このときの磁石粉の残留磁化は８００Ｇであった。次いで同様に４ｋＯｅの磁場中において再び配向させ、その後、１．０ｔ／ｃｍ^２の成形圧にて成形した以外は実施例６と同様に成形した。
【００７８】
これらの成形体はＡｒガス中１０９０℃で１時間焼結を行い、引き続き５８０℃で１時間の時効熱処理を行った。その後、加工を行い、φ２４ｍｍ×φ１９ｍｍ×Ｌ３０ｍｍの円筒磁石を得た。なお、本円筒磁石と同一磁石粉を用い、水平磁場垂直成形装置にて１２ｋＯｅの磁場中において１．０ｔ／ｃｍ^２の成形圧にて成形し、Ａｒガス中１０９０℃で１時間焼結を行い、引き続き５８０℃で１時間の熱処理をして本円筒磁石と同一条件で作製したブロック磁石の特性は、Ｂｒ：１２．５ｋＧ、ｉＨｃ：１５ｋＯｅ、（ＢＨ）ｍａｘ：３６ＭＧＯｅであった。上記の円筒磁石を、図７に示す着磁機にて６極、２０°でスキュー着磁し、着磁後の磁石を磁石と同一高さの図１０に示す構成のステータ内に組み込んだモータを作製した。また、上記実施例のモータを５０００ｒｐｍで回転させた際の誘起電圧及び同モータを５ｒｐｍで回転させた際の荷重計によるトルクリップルの大きさを測定した。更に、上記と同様に成形、焼結、熱処理して得た円筒磁石を図８の着磁機にて着磁し、モータに組み込んで、誘起電圧及びトルクリップルを測定した（実施例８ａ）。表３に誘起電圧の絶対値の最大及びトルクリップルの最大最小の差を示す。
【００７９】
実施例９として、実施例６と同じ水平磁場垂直成形装置を用い、１２ｋＯｅの磁場中において９０°回転させながら配向を行い、１．０ｔ／ｃｍ^２の成形圧にて成形した。他は実施例６と同様にして作製した磁石を用いたモータのモータ特性を測定した。
【００８０】
一方、参考例１として、実施例６において４ｋＯｅの磁場で配向させた際、回転させずそのまま磁界中１．０ｔ／ｃｍ^２の成形圧にて成形した。他は実施例６と同様にして作製した磁石を用いたモータのモータ特性を測定した。これらの結果を表３に示す。
【００８１】
【表３】

【００８２】
表３より、参考例に対し実施例ではトルクに相応する誘起電圧が大きく改善されており、本発明がモータ用磁石の製造方法として優れた方法であることがわかる。
【００８３】
なお、実施例６の着磁後のロータ磁石の表面磁束を測定した結果は図１１と同様の結果で各極が均一化しており、かつ極の面積が大きくなっており、実施例は大きな磁場が均一に発生できることがわかる。
【００８４】
［実施例１０］
それぞれ純度９９．７重量％のＮｄ、Ｄｙ、Ｆｅ、Ｃｏ、Ｍ（ＭはＡｌ、Ｓｉ、Ｃｕ）と純度９９．５重量％のＢを用い、Ｎｄ_２９Ｄｙ_２．５Ｆｅ_６４Ｃｏ_３Ｂ_１Ａｌ_０．２Ｓｉ_０．２Ｃｕ_０．１の合金を真空溶解炉で溶解鋳造してインゴットを作製した。このインゴットをジョウクラッシャー及びブラウンミルで粗粉砕し、更に窒素気流中ジェットミル粉砕により平均粒径３．５μｍの微粉末を得た。この粉末を飽和磁束密度２０ｋＧのＦｅ製の強磁性体コアを配置した図１に示す水平磁場垂直成形装置にて１０ｋＯｅの磁場中において１．０ｔ／ｃｍ^２の成形圧にて成形した。この成形体はＡｒガス中１０９０℃で１時間焼結を行い、引き続き５８０℃で１時間の熱処理を行った。その後加工を行い、φ３０ｍｍ×φ２５ｍｍ×Ｌ３０ｍｍの円筒磁石を得た。本円筒磁石と同一磁石粉を用い、水平磁場垂直成形装置にて１０ｋＯｅの磁場中において１．０ｔ／ｃｍ^２の成形圧にて成形し、Ａｒガス中１０９０℃で１時間焼結を行い、引き続き５８０℃で１時間の熱処理をして、本円筒磁石と同一条件で作製したブロック磁石の特性は、Ｂｒ：１３．０ｋＧ、ｉＨｃ：１５ｋＯｅ、（ＢＨ）ｍａｘ：４０ＭＧＯｅであった。
【００８５】
上記の径方向配向円筒磁石を、着磁機にて６極着磁し、着磁後の磁石を磁石と同一高さの図１０に示す構成の９個のステータ内に組み込んだモータを作製した。磁石内径にはモータ軸となる強磁性コアが挿入接着されている。銅細線を各歯それぞれ１００ターン巻きとした。Ｕ−Ｖ相間の磁束量をフラックスメータを用いて測定した。
【００８６】
［比較例４］
本ステータ歯のうちの一つだけに実施例１０と同じ銅細線を１００ターン巻き、磁束量をフラックスメータにて測定した。磁石を１周させたときのピークの値を表４に示す。表に示されるように、比較例ではピークによる磁束量が、小さいピークに対し大きなピークでは１．５倍程度と非常に大きいにもかかわらず、実施例１０ではピーク値がほとんど変わらない。
【００８７】
［実施例１１］
コア断面積の６０％の面積を占める飽和磁束密度１８ｋＧの強磁性体をコア外周と同心円状に配置し、残りは非磁性体材で作製したコアを用い、その他は実施例１０と同様にして作製したモータのＵ−Ｖ相間の磁束量を測定した。
【００８８】
［比較例５］
非磁性体（非磁性超硬材ＷＣ−Ｎｉ−Ｃｏ）をコア材に用いた他は実施例１０と同様にして作製したモータのＵ−Ｖ相間の磁束量を測定した。
【００８９】
［比較例６］
Ｆｅ製の強磁性体コアの飽和磁束密度を２ｋＧとした他は実施例１０と同様にして作製したモータのＵ−Ｖ相間の磁束量を測定した。配置した際のモータのＵ−Ｖ相間の磁束量をそれぞれフラックスメータを用いて測定した。
これらの結果を表４に示す。
【００９０】
【表４】

【００９１】
［実施例１２］
実施例１０のモータを１０００ｒｐｍで回転させた際の誘起電圧及び同モータを１〜５ｒｐｍで回転させた際の荷重計によるトルクリップルの大きさを測定した。表５に誘起電圧の絶対値の最大及びトルクリップルの最大最小の差を示す。表５より、本モータは使用上十分な誘起電圧量を有し、十分小さなトルクリップルであることがわかる。
【００９２】
［実施例１３］
実施例１０の径方向配向円筒磁石を着磁する際、スキュー角度を磁石１極分の角度の１／３の２０°でスキュー着磁を行い、該磁石を実施例１０のモータに組み込み、実施例１２と同様に誘起電圧及びトルクリップルを測定した値を表５に示す。表５よりトルクリップルの量がスキュー無し品より更に小さく、誘起電圧の低下はわずかであることがわかる。
【００９３】
［参考例２］
実施例１０の径方向配向円筒磁石を着磁する際、スキュー角度磁石１極分の角度の５／６の５０°でスキュー着磁を行い、該磁石を実施例１０のモータに組み込み、実施例１２と同様に誘起電圧及びトルクリップルを測定した値を表５に示す。表５よりトルクリップルの量はスキュー無し品より小さいが、誘起電圧の低下が大きく、実用に適さない場合があることがわかる。
【００９４】
［実施例１４］
径方向配向円筒磁石を実施例１０と同様に着磁し、スキュー角度が磁石１極分の角度の１／３の２０°であるステータ歯をもつ実施例１０と同寸法のモータに組み込み、実施例１２と同様に誘起電圧及びトルクリップルを測定した値を表５に示す。表５より、トルクリップルの量がスキュー無し品より更に小さく、誘起電圧の低下はわずかであることがわかる。
【００９５】
【表５】

【００９６】
［実施例１５］
それぞれ純度９９．７重量％のＮｄ、Ｄｙ、Ｆｅ、Ｃｏ、Ｍ（ＭはＡｌ、Ｓｉ、Ｃｕ）と純度９９．５重量％のＢを用い、Ｎｄ_２９Ｄｙ_２．５Ｆｅ_６４Ｃｏ_３Ｂ_１Ａｌ_０．２Ｓｉ_０．２Ｃｕ_０．１の合金を真空溶解炉で溶解鋳造し、インゴットを作製した。このインゴットをジョウクラッシャー及びブラウンミルで粗粉砕し、更に、窒素気流中でのジェットミル粉砕により平均粒径３．５μｍの微粉末を得た。この粉末を飽和磁束密度２０ｋＧのＦｅ製の強磁性体コアを配置した図１に示す如き水平磁場垂直成形装置にて６ｋＯｅの磁場中において１．０ｔ／ｃｍ^２の成形圧にて成形した。この成形体は、Ａｒガス中１０９０℃で１時間焼結を行い、引き続き５８０℃で１時間の熱処理を行った。その後、加工して外径３０ｍｍ、内径２５ｍｍ、厚さ１５ｍｍの円筒磁石を得た。
【００９７】
実施例１５は、作製した円筒磁石を、配向方向を６０°ずらして積み重ね、１段目の磁石配向方向が図８の関係（極ＡがＮ極となる）になるように配置し、６極着磁３段積みを行った。
【００９８】
［実施例１６］
実施例１６は、ずらし角を９０°とし、実施例１５と同様に６極着磁２段積みを行った。
【００９９】
［参考例３］
実施例１５と同じ磁石粉末を用い、成形体高さを変え、段積みをしないこと以外は実施例１５と同一条件で外径３０ｍｍ、内径２５ｍｍ、厚さ３０ｍｍの円筒磁石を作製し、６極着磁を行った。
【０１００】
［実施例１７］
実施例１５と同じ磁石粉末を用い、同一条件で外径３０ｍｍ、内径２５ｍｍ、厚さ１０ｍｍの円筒磁石を作製し、配向方向を６０°ずらして３段積み重ね、各段の円筒磁石の配向方向がそれぞれ図７の配置になるようにし、６極着磁を行った。この様子を図１６に示す。図中の大矢印は、円筒磁石の各段の配向時の磁場方向を示している。なお、符号３３はモータロータ軸である。
【０１０１】
これらの磁石を評価するために、横１０．５ｍｍ、縦３０ｍｍの四角形に銅細線を５０ターン巻き、コイルを作製した。このコイルを円筒磁石に接した状態から磁石の磁力の影響を受けない遠方まで遠ざけ、この間のコイルを横切る磁束量を円筒磁石の外周方向にフラックスメータを用いて測定し、ピーク値を表６に示す。
【０１０２】
【表６】

【０１０３】
［実施例１８，１９、参考例４、比較例７］
図１０は、９個のモータステータ歯３１を有する３相の永久磁石モータ３０の平面図を示したものである。着磁した円筒磁石をこの磁石と同一高さのステータ内に組み込んでモータを作製した。円筒磁石の内径部にはモータ軸となる強磁性コアが挿入接着されている。各ティースに銅細線をそれぞれ１５０ターン巻きした。このモータを１０００ｒｐｍで回転させ、このときの誘起電圧の絶対値の最大で、かつ１〜５ｒｐｍで回転させ、荷重計を用いてトルクリップルの大きさを測定した。
【０１０４】
ここで、実施例１８は、実施例１６と同様にずらし角９０°で磁石を２段に重ね合わせ、スキュー角を磁石１極分の角度の１／３の２０°でスキュー着磁を行い、この磁石をモータに組み込んだものである。
【０１０５】
実施例１９は、実施例１７と同じ寸法の円筒磁石を用い、図１６に示すようにずらし角６０°で磁石を３段に重ねてスキューなしに着磁し、スキュー角が磁石１極分の角度の１／３の２０°であるスキューステータ歯を有するモータに組み込んだものである。
【０１０６】
また、段積みをしない円筒磁石を参考例４とし、また成形金型のコアを非磁性（非磁性超硬材ＷＣ−Ｎｉ−Ｃｏ）で作製して成形機に配置し、その他は実施例１５と同様に磁石を作製し、これを実施例１８と同様にしてモータに組み込み、比較例７とした。これらの誘起電圧、トルクリップルを測定し、誘起電圧とともにトルクリップルの最大最小の差を表７に示した。
【０１０７】
表７から、各実施例は実用に十分耐える誘起電圧を有し、トルクリップルも十分小さいが、参考例４はトルクリップルが大きいことが認められる。比較例７は誘起電圧が低く、実用に適さない。
【０１０８】
［参考例５］
実施例１８の径方向配向円筒磁石を着磁する際、スキュー角磁石１極分の角度の５／６の５０°でスキュー着磁を行い、この磁石を図１０のモータに組み込み、実施例１８と同様にして誘起電圧及びトルクリップルを測定し、表７に示した。
【０１０９】
表７から、トルクリップルの量は小さいが、誘起電圧の低下が大きく実用に適さないことが認められる。
【０１１０】
［実施例２０、参考例６］
実施例１５のＮｄ磁石合金を用いて、水平磁場垂直成形法により一軸配向のリング磁石を作製した。磁石寸法は外径２５ｍｍ、内径２０ｍｍ、厚さ１５ｍｍである。配向方向を６０°ずつ変化させながら６段積み重ねて６極にストレート着磁し磁石ロータを作製した。これを７°のスキュー角のステータに組み込みモータにした。
【０１１１】
更に参考例６として、実施例２０と同じ磁石を用いて配向方向を一方向にそろえ、６極にストレート着磁し磁石ロータを作製した。これを無スキューのステータに組み込みモータにした。これらにおいて誘起電圧とともにトルクリップルを測定した。
【０１１２】
その結果は、表７に示したとおりであり、実施例２０では参考例６に比べてトルクリップルが大きく低下しており、本発明による磁石の配向方向分散の効果が顕著であることがわかる。
【０１１３】
【表７】

【図面の簡単な説明】
【図１】円筒磁石を製造する際に使用する水平磁場垂直成形装置の一実施例を示す説明図であり、（ａ）は平面図、（ｂ）は縦断面図である。
【図２】ラジアル異方性円筒磁石を製造する際に使用する従来の垂直磁場垂直成形装置を示す説明図であり、（ａ）は縦断面図、（ｂ）は（ａ）図におけるＡ−Ａ’線の断面図である。
【図３】円筒磁石を製造する際に使用する水平磁場垂直成形装置で磁場発生時の磁力線の様子を模式的に示す説明図であり、（ａ）は本発明に係る成形装置の場合、（ｂ）は従来の成形装置の場合である。
【図４】円筒磁石を製造する際に使用する水平磁場垂直成形装置の他の実施例を示す説明図であり、（ａ）は平面図、（ｂ）は縦断面図である。
【図５】ラジアル異方性円筒磁石を製造する際に使用するダイス部に一部非磁性材を配置した垂直磁場垂直成形装置を示す説明図であり、（ａ）は図２（ｂ）と同様の断面図、（ｂ）は（ａ）図におけるＢ１〜Ｂ４部の拡大図である。
【図６】円筒磁石を製造する際に使用する成形装置で、回転式水平磁場垂直成形装置の一例を示す説明図である。
【図７】着磁機を用いて円筒磁石の着磁を行う様子を示す着磁模式図である。
【図８】着磁機を用いて円筒磁石の着磁を行う様子を示す着磁模式図で、円筒磁石の配向方向を図７に対して９０°回転させて着磁を行う様子を示す。
【図９】円筒磁石のＮ極とＳ極との境界を説明する平面図である。
【図１０】６極に多極着磁した円筒磁石と９個のステータ歯を組み合わせた３相モータの平面図を示したものである。
【図１１】本発明に係る水平磁場垂直成形装置により作製したＮｄ−Ｆｅ−Ｂ系円筒磁石に６極着磁を行った際の表面磁束密度を示した図である。
【図１２】従来の水平磁場垂直成形装置（コア材として非磁性材を使用）により作製したＮｄ−Ｆｅ−Ｂ系円筒磁石に６極着磁を行った際の表面磁束密度を示した図である。
【図１３】円筒磁石を製造する際に使用する強磁性材をコアとして用いた水平磁場垂直成形装置により作製された磁石の配向磁場方向に対し、３０°方向での磁石の配向を示す顕微鏡写真である。
【図１４】円筒磁石を製造する際に使用する強磁性材をコアとして用いた水平磁場垂直成形装置により作製された磁石の配向磁場方向に対し、６０°方向での磁石の配向を示す顕微鏡写真である。
【図１５】円筒磁石を製造する際に使用する強磁性材をコアとして用いた水平磁場垂直成形装置により作製された磁石の配向磁場方向に対し、９０°方向での磁石の配向を示す顕微鏡写真である。
【図１６】径方向配向円筒磁石を各６０°ずらして３段に積層した本発明の永久磁石式モータ用ロータを示す斜視図である。
【符号の説明】
１ 成形機架台
２ 配向磁場コイル
３ ダイス
４ コア
５ コア
５ａ コア
５ａ’ 弱い強磁性体超硬合金部
６ 上パンチ
７ 下パンチ
８ 充填磁石粉
９ ポールピース
１０ ダイス非磁性体
１１ パーメンジュール
２１ 円筒磁石
２２ 着磁機
２３ 着磁機磁極歯
２４ 着磁機コイル
３０ ３相モータ
３１ ステータ歯
３２ コイル
３３ モータロータ軸[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a radially anisotropic sintered magnet and a method for manufacturing a radially anisotropic sintered magnet. The present invention also relates to a cylindrical magnet rotor for a synchronous permanent magnet motor such as a servo motor and a spindle motor, and to an improvement of a permanent magnet motor using the same.
[0002]
[Prior art]
Anisotropic magnets made by pulverizing crystalline magnetic anisotropic materials such as ferrites and rare earth alloys and performing press molding in a specific magnetic field are widely used in speakers, motors, measuring instruments, and other electrical equipment. It is used. Among them, magnets having anisotropy in the radial direction are particularly excellent in magnetic properties, can be freely magnetized, and do not require reinforcement for fixing magnets such as segment magnets. Used in brushless motors and the like. In particular, in recent years, a long radial anisotropic magnet has been demanded as the performance of a motor becomes higher.
[0003]
A magnet having a radial orientation is manufactured by a vertical magnetic field vertical molding method or a backward extrusion method. The vertical magnetic field vertical molding method is characterized in that a magnetic field is applied from a pressing direction to a counter direction through a core to obtain a radial orientation. That is, in the vertical magnetic field vertical molding method, as shown in FIG. 2, the magnetic field generated in the orientation magnetic field coil 2 is opposed via the cores 4 and 5, the core passes through the die 3, and the molding machine base 1 In the magnetic circuit that circulates through the magnetic powder, the filled magnet powder 8 is radially oriented. In the figure, 6 is an upper punch and 7 is a lower punch.
[0004]
As described above, in the vertical magnetic field vertical forming apparatus, the magnetic field generated by the coil forms a core, a die, a molding machine base, and a magnetic path serving as a core. In this case, in order to reduce the magnetic field leakage loss, a ferromagnetic material is used as a material of a portion forming a magnetic path, and an iron-based metal is mainly used. However, the magnetic field strength for orienting the magnet powder is determined as follows. The core diameter is B (magnet powder filling inner diameter), the die diameter is A (magnet powder filling outer diameter), and the magnet powder filling height is L. The magnetic flux passing through the upper and lower cores strikes at the center of the core, opposes each other, and reaches the dice. The amount of magnetic flux passing through the core is determined by the saturation magnetic flux density of the core, and the magnetic flux density of an iron core is about 20 kG. Therefore, the orientation magnetic field at the inner and outer diameters of the magnet powder filling is obtained by dividing the amount of magnetic flux passing through the upper and lower cores by the inner area and the outer area of the magnet powder filling portion,
2 · π · (B / 2) ² 20 / (π · B · L) = 10 · B / L: inner circumference,
2 · π · (B / 2) ² · 20 / (π · A · L) = 10 · B ² / (AL): Outer circumference
It becomes. Since the magnetic field at the outer circumference is smaller than the inner circumference, 10 kOe or more is required at the outer circumference in order to obtain a good orientation in all the magnet powder filling portions. ² / (AL) = 10, so that L = B ² / A. The height of the compact is about half of the height of the filling powder and becomes about 80% during sintering, so that the height of the magnet is extremely small. As described above, since the saturation of the core determines the strength of the alignment magnetic field, the size, that is, the height of the orientable magnet is determined by the shape of the core, and it is difficult to manufacture a long product in the cylindrical axis direction. In particular, only a very short product could be manufactured with a cylindrical magnet having a small diameter.
[0005]
In addition, the rear extrusion method requires large facilities, has a low yield, and it is difficult to manufacture an inexpensive magnet.
[0006]
As described above, the radial anisotropic magnet is difficult to manufacture by any method, it is more difficult to manufacture it in a large amount at low cost, and the motor using the radial anisotropic magnet has a disadvantage that the cost is very high. was there.
[0007]
When manufacturing a radially anisotropic ring magnet with a sintered magnet, it is generated due to the difference in linear expansion coefficient between the C-axis direction and the C-axis perpendicular direction of the magnet in the sintering and aging cooling process due to anisotropy. If the stress is greater than the mechanical strength of the magnet, cracks and cracks occur, which is problematic. For this reason, it was possible to manufacture the R—Fe—B based sintered magnet only in a magnet shape having an inner / outer diameter ratio of 0.6 or more (Hitachi Metals Technical Report Vol. 6, p. 33-36). Further, in the R- (Fe, Co) -B sintered magnet, Co substituted for Fe is contained not only in the main phase 2-14-1 in the alloy structure but also in the R-rich phase. ₃ Form Co to significantly reduce mechanical strength. Moreover, since the Curie temperature is high, the amount of change in the coefficient of thermal expansion in the C-axis direction and the C-axis vertical direction between the Curie temperature during cooling and room temperature increases, and the residual stress which causes cracks and cracks increases. For this reason, the R- (Fe, Co) -B-based radial anisotropic ring magnet is more severely restricted in shape than the R-Fe-B-based magnet containing no Co, and is stable only when the inner / outer diameter ratio is 0.9 or more. Magnet production could not be done. For the same reason, cracks and cracks occur in ferrite magnets and Sm-Co magnets, and stable production cannot be achieved.
[0008]
The circumferential residual stress causing cracks or cracks generated during the sintering and aging cooling processes accompanying the radial anisotropy is based on the results of Kools' study of ferrite magnets (F. Kools: Science of Ceramics. Vol. 7, (1973), 29-45), and is represented as equation (1).
σ _θ = ΔTΔαEK ² / (1-K ² ) ・ (Kβ _K η ^K-1 -Kβ _-K η ^-K-1 -1) ‥‥‥ (1)
σ _θ : Circumferential stress
ΔT: temperature difference
Δα: Difference in linear expansion coefficient (α‖-α⊥)
E: Young's modulus in orientation direction
K ² : Anisotropy ratio of Young's modulus (E⊥ / E‖)
η: Position (r / outer diameter)
β _k : (1-ρ ^{1 + K} ) / (1-ρ ^2K )
ρ: Inner / outer diameter ratio (inner / outer diameter)
[0009]
In the above equation, the term that has the largest influence on the cause of cracks or cracks is Δα: difference in linear expansion coefficient (α‖−α⊥), and is a ferrite magnet, an Sm—Co-based rare earth magnet, Nd—Fe—. In a B-based rare earth magnet, the difference in the coefficient of thermal expansion depending on the crystal direction (thermal expansion anisotropy) appears from the Curie temperature, and increases as the temperature decreases during cooling. At this time, the residual stress becomes higher than the mechanical strength of the magnet, leading to cracking.
[0010]
According to the above formula, the stress due to the difference in thermal expansion between the orientation direction and the direction perpendicular to the orientation direction occurs because the cylindrical magnet is radially oriented in the radial direction. Accordingly, if a cylindrical magnet having a partly different orientation from the radial orientation is manufactured, no cracking occurs. For example, a cylindrical magnet produced by a horizontal magnetic field vertical molding method and oriented in one direction perpendicular to the cylindrical axis may be any one of a ferrite magnet, an Sm-Co rare earth magnet, and an Nd-Fe (Co) -B rare earth magnet. It does not break even with type magnets.
[0011]
Multipolar magnetization can be performed on a cylindrical magnet without using individual radial anisotropic magnets, and if the magnetic flux density is high and the variation in magnetic flux density between the poles is small, the magnet can be used as a high-performance permanent magnet motor. A magnet oriented in one direction perpendicular to the cylinder axis by the horizontal magnetic field vertical molding method, and only the magnetization is multipole, making a cylindrical multipole magnet for permanent magnet motor without using a radial anisotropic magnet (MAG-85-120, 1985). Magnets manufactured by the horizontal magnetic field vertical molding method and oriented in one direction perpendicular to the cylinder axis (hereinafter referred to as radially oriented cylindrical magnets) are as long as possible (50 mm or more) as long as the press machine cavity allows. In addition, since multiple presses can be performed, a large number of compacts can be obtained by one press, and a cylindrical magnet for a motor can be supplied at a low cost instead of an expensive radial anisotropic magnet.
[0012]
However, in practice, magnets obtained by performing multipolar magnetization on a radially oriented cylindrical magnet produced by the horizontal magnetic field vertical molding method have a high magnetic flux density near the direction of the orientation magnetic field and a pole perpendicular to the direction of the orientation magnetic field. However, since the magnetic flux density is small, when the motor is assembled to the motor and the motor is rotated, torque unevenness reflecting the variation of the magnetic flux density between the poles occurs, and it cannot be said that the magnet is a motor magnet that can be practically used.
[0013]
In order to solve this problem, in Patent Document 1, the number of circumferentially magnetized poles in a cylindrical magnet manufactured by a horizontal magnetic field vertical forming method and oriented in one direction perpendicular to the cylinder axis is 2n (n is larger than 1). It has been proposed that the number of teeth of the stator combined with the cylindrical magnet be 3 m (m is a positive integer larger than 1 and smaller than 33) when the number is larger than 50 (positive integer). According to Patent Document 2, when the number of magnetized poles is k (k is a positive even number of 4 or more), the number of teeth of a stator combined with this cylindrical magnet is 3 k · j / 2 (j is a positive integer of 1 or more). It has been proposed. Further, Patent Document 3 proposes reducing the torque unevenness by stacking cylindrical magnets oriented in one direction perpendicular to the cylindrical axis at different angles and stacking them.
[0014]
However, in all of Patent Literatures 1 to 3, although torque unevenness is reduced, a radial magnet having a small number of radially oriented portions in a ring magnet has a total torque of 70% as compared with a radial magnet having the same magnetic characteristics. Small and not yet practical.
[0015]
[Patent Document 1]
JP 2000-116089 A
[Patent Document 2]
JP-A-2000-116090
[Patent Document 3]
JP 2000-175387 A
[Non-patent document 1]
Hitachi Metals Technical Report Vol. 6, p. 33-36
[Non-patent document 2]
F. Kools: Science of Ceramics.
Vol. 7, (1973), p. 29-45
[Non-Patent Document 3]
IEICE Magnetics Research Group Material
MAG-85-120, 1985
[0016]
[Problems to be solved by the invention]
Accordingly, a first object of the present invention is to provide a radially anisotropic sintered magnet having excellent magnet properties free from cracks and cracks during sintering and aging cooling even in a shape having a small inner / outer diameter ratio. .
A second object of the present invention is to provide a method for manufacturing a radially anisotropic sintered magnet capable of easily producing multiple and long products and realizing a high-performance permanent magnet motor at low cost. Is to do.
A third object of the present invention is to provide an inexpensive and high-performance permanent magnet motor.
A fourth object of the present invention is to perform multi-polar magnetization without using a radial anisotropic magnet, to have a high magnetic flux density and a small variation in magnetic flux density between poles. An object of the present invention is to provide an inexpensive, mass-produced multi-stage long multi-pole magnetized cylindrical magnet rotor with torque and without torque unevenness, and a permanent magnet motor using the same.
[0017]
Means for Solving the Problems and Embodiments of the Invention
In order to achieve the first object, the present invention contains a portion formed in a cylindrical shape and inclined in a direction inclined by 30 ° or more with respect to a radial direction in an amount of 2% or more and 50% or less of the magnet volume. A radially anisotropic sintered magnet, characterized in that the portion is oriented in a radial direction or an inclination with respect to the radial direction of less than 30 °. As a method for obtaining such a magnet, a ferromagnetic material having a saturation magnetic flux density of 5 kG or more is used for at least a part of a core of a molding die for a cylindrical magnet, and a magnet powder filled in a mold cavity is vertically and horizontally magnetically magnetized. A method for producing a radially anisotropic sintered magnet, characterized in that an orientation magnetic field is applied to a magnet powder by a molding method to form the magnet powder. In this case, the magnetic field generated by the horizontal magnetic field vertical shaping is preferably 0.5 to 12 kOe. Furthermore, the present invention provides a die for a cylindrical magnet molding die, in which at least one non-magnetic material is disposed over a region having a total angle of 20 ° or more and 180 ° or less, and the magnetic powder filled in the mold cavity is vertically placed. A method for producing a radially anisotropic sintered magnet, characterized in that a magnetic field is applied to a magnet powder by a magnetic field vertical molding method to form the magnet powder.
[0018]
That is, the present inventors have made intensive efforts to achieve the above object, and as a result, the radial orientation of the cylindrical magnet is entirely radially oriented and partially intentionally disturbed. It has been found that a stable production free of cracks and cracks can be realized in the cooling process during aging, and that a large torque can be obtained when assembled into a motor.
[0019]
ADVANTAGE OF THE INVENTION According to this invention, even if it is a shape with a uniform magnetic field and a small inner-to-outer diameter ratio, it is free from cracks and cracks during sintering and aging cooling, and has excellent magnet properties and is an R-Fe (Co) -B-based radial anisotropic material. Stable magnets can be produced stably, which is useful for high performance, high power, miniaturization, etc. of AC servo motors, DC brushless motors, speaker magnets, etc., and especially for automotive throttle valves. It is also effective in the production of the radially-directed two-pole magnetized magnet used, and it is possible to supply inexpensively and in large quantities a cylindrical magnet for a synchronous magnet motor having excellent performance.
[0020]
Further, in order to achieve the second object, the present invention uses a ferromagnetic material having a saturation magnetic flux density of 5 kG or more for at least a part of a material of a core of a molding die for a cylindrical magnet, and fills the mold cavity. A method for producing a radial anisotropic magnet by applying an orientation magnetic field to a magnet powder by a horizontal magnetic field vertical molding method and shaping the magnet powder, comprising the following steps (i) to (v):
(I) rotating the magnet powder by a predetermined angle in the circumferential direction of the mold while applying a magnetic field;
(Ii) After applying the magnetic field, rotate the magnet powder by a predetermined angle in the circumferential direction of the mold, and then apply the magnetic field again.
(Iii) rotating the magnetic field generating coil with respect to the magnet powder by a predetermined angle in the circumferential direction of the mold during application of the magnetic field;
(Iv) After applying the magnetic field, rotate the magnetic field generating coil by a predetermined angle in the circumferential direction of the mold with respect to the magnet powder, and then apply the magnetic field again.
(V) Two or more pairs of magnetic field generating coils are arranged, and one pair of coils applies a magnetic field, and then another coil pair applies a magnetic field.
A method of manufacturing a radial anisotropic magnet, wherein at least one of the above operations is performed. Here, when rotating the charged magnetic powder, the charged magnetic powder can be rotated by rotating at least one of the core, the die, and the punch in the circumferential direction. When the magnetic powder is rotated after applying the magnetic field, the value of the residual magnetization of the ferromagnetic core or the magnetic powder is 50 G or more, and the magnetic powder can be rotated by rotating the core in the circumferential direction. In this case, the magnetic field generated in the horizontal magnetic field vertical forming step is preferably 0.5 to 12 kOe.
[0021]
According to the second invention, multiple and long products can be easily produced without using an expensive radial anisotropic magnet with low productivity, and the magnetic field is uniform, inexpensive, and stably supplied in large quantities. High performance permanent magnet motors can be realized using radially oriented cylindrical magnets manufactured by the horizontal magnetic field vertical molding method, which is useful for reducing the price of high performance motors such as AC servo motors and DC brushless motors. It is.
[0022]
In order to achieve the third object, the present invention provides a permanent magnet motor in which a radially anisotropic cylindrical magnet is incorporated in a motor having a plurality of stator teeth, wherein the cylindrical magnet is a core of a molding die for a cylindrical magnet. A ferromagnetic material having a saturation magnetic flux density of 5 kG or more is used for at least a part of the material, and a magnet powder filled in a mold cavity is formed by applying an orientation magnetic field to the magnet powder by a horizontal magnetic field vertical molding method. When the number of magnetic poles in the circumferential direction is 2n (n is a positive integer of 2 to 50) in an anisotropic cylindrical magnet, the number of teeth of a stator combined with the cylindrical magnet is 3 m (m is 2 to 33). The following positive integer is provided, and 2n ≠ 3m is provided. In this case, when the number of magnetized poles in the circumferential direction of the cylindrical magnet is k (k is a positive even number of 4 or more), the number of teeth of the stator combined with this cylindrical magnet is 3k · j / 2 (j is a positive number of 1 or more). And the boundary between the north pole and the south pole of the cylindrical magnet is within 10 ° with respect to the central portion of the portion oriented in a direction inclined at least 30 ° with respect to the radial direction. Is preferred. Further, it is preferable that the skew angle of the cylindrical magnet is 1/10 to 2/3 of the angle of one pole of the cylindrical magnet, and the multipole skew is magnetized. In particular, the skew angle of the stator teeth is one pole of the cylindrical magnet. It is preferable to have a skew tooth of 1/10 to 2/3 of the angle. Further, it is preferable to use a magnet formed by setting the magnetic field generated by the horizontal magnetic field vertical shaping to 0.5 to 12 kOe.
[0023]
ADVANTAGE OF THE INVENTION According to this invention, the cylindrical magnet used for a synchronous magnet motor with excellent performance can be supplied in large quantities, especially at a long size and at low cost.
[0024]
In order to achieve the fourth object, the present invention provides a magnet powder filled in a mold cavity using a ferromagnetic material having a saturation magnetic flux density of 5 kG or more for at least a part of a core of a molding die for a cylindrical magnet. Is formed by applying an orientation magnetic field to a magnet powder by a horizontal magnetic field vertical molding method, and a plurality of radially anisotropic cylindrical magnets obtained by multipolar magnetization are stacked in two or more stages in the axial direction. A multi-stage long multi-pole magnetized cylindrical magnet rotor is provided. In this case, assuming that the number of stacked cylindrical magnets is i (i is a positive integer of 2 or more and 10 or less), the same direction as the orientation magnetic field direction of each cylindrical magnet is shifted by 180 / i ° to stack i pieces. In addition, when the number of poles of the multipolar magnetization is n (n is a positive integer of 4 or more and 50 or less), the number i of stacks and the number n of poles may have a relationship of i = n / 2. preferable. Further, when performing multi-pole magnetization of n poles on the outer peripheral surface of the cylindrical magnet, the angle of one pole is set to 360 / n °, and skew magnetization is performed at an angle of 1/10 to ／ of this angle. Is preferred. The present invention also provides a permanent magnet type motor using the multi-stage long multi-pole magnetized cylindrical magnet rotor.
[0025]
In other words, by adopting the above configuration, the variation of the magnetic flux density between the poles is greatly reduced, and the motor magnet capable of realizing smooth rotation without torque unevenness with high torque, that is, a multi-stage long multi-pole magnetized cylindrical magnet rotor And a permanent magnet type motor using the same can be manufactured.
[0026]
Hereinafter, the present invention will be described in more detail.
The radially anisotropic sintered magnet according to the present invention is a cylindrical magnet, which is generally oriented in the radial direction (radial direction), provided that a portion of 2% or more and 50% or less of the magnet volume in the radial direction. On the other hand, the orientation is 30 ° or more and 90 ° or less.
[0027]
In the radially anisotropic sintered magnet of the present invention, the portion oriented in such a direction inclined by 30 to 90 ° with respect to the radial direction is 2 to 50% of the magnet volume.
[0028]
That is, the stress represented by the above-described formula (1) is generated because the continuum is radially oriented in the circumferential direction, that is, a cylindrical magnet. Therefore, if partial continuous orientation is disturbed, the stress decreases. Therefore, a magnet that can be produced without cracking by containing a portion oriented in a direction inclined by 30 ° or more with respect to the radial direction by 2% or more and 50% or less of the magnet volume. When the portion inclined at 30 ° or more is smaller than 2%, the effect of preventing cracking is small, and when the portion inclined at 30 ° or more is more than 50%, the torque for the motor rotor is insufficient, which is not practical. More preferably, a portion inclined by 30 ° or more is contained at 5 to 40%, more preferably 10 to 40%.
[0029]
The remaining magnet volume portion, that is, the portion of the magnet volume of 50 to 98%, more preferably 60 to 95%, is oriented so that the inclination from the radial direction to the radial direction is less than 30 °. is there.
[0030]
FIG. 1 is an explanatory view of a horizontal magnetic field vertical forming apparatus for performing orientation in a magnetic field when forming a cylindrical magnet, and particularly a horizontal magnetic field vertical forming apparatus for a motor magnet. Here, as in the case of FIG. 2, 1 indicates a molding machine stand, 2 indicates an orientation magnetic field coil, 3 indicates a die, and 5a indicates a core. 6 is an upper punch, 7 is a lower punch, 8 is a charged magnetic powder, and 9 is a pole piece.
[0031]
In the present invention, at least a part, preferably the whole, of the core 5a is formed of a ferromagnetic material having a saturation magnetic flux density of 5 kG or more, preferably 5 to 24 kG, more preferably 10 to 24 kG. Examples of the core material include a ferromagnetic material using a material such as an Fe-based material, a Co-based material, or an alloy thereof.
[0032]
As described above, when a ferromagnetic material having a saturation magnetic flux density of 5 kG or more is used for the core, when an orientation magnetic field is applied to the magnet powder, the magnetic flux draws lines of magnetic force close to radial because it tends to enter the ferromagnetic material perpendicularly. Therefore, as shown in FIG. 3A, the magnetic field direction of the magnet powder filling portion can be made closer to the radial orientation. On the other hand, conventionally, the entire core 5b is made of a non-magnetic material or a material having a saturation magnetic flux density equivalent to that of the magnet powder. In this case, the magnetic lines of force are parallel to each other as shown in FIG. The vicinity is the radial direction, but the direction of the orientation magnetic field by the coil becomes higher and lower. Even if the core is formed of a ferromagnetic material, if the saturation magnetic flux density of the core is less than 5 kG, the core is easily saturated, and the magnetic field is close to that of FIG. 3B despite the use of the ferromagnetic core. . In addition, if it is less than 5 kG, it becomes equal to the saturation density of the charged magnet powder (saturation magnetic flux density of the magnet × filling rate), and the direction of the magnetic flux in the charged magnet powder and the ferromagnetic core becomes equal to the magnetic field direction of the coil.
[0033]
When a ferromagnetic material of 5 kG or more is used for a part of the core, the same effect as described above can be obtained and is effective. FIG. 4 shows an example in which a part (central part) is a ferromagnetic substance and an outer peripheral part is a weak ferromagnetic substance (WC-Ni-Co-based). In FIG. 4, 5a 'indicates a weak ferromagnetic hard metal part, and 11 indicates permendur.
[0034]
According to the above method, since the disturbance to the radial orientation in the radial direction in the cylindrical magnet becomes the disturbance of the orientation only in a portion perpendicular to the direction of the orientation magnetic field, the decrease in the magnetic flux amount of each pole after the magnetization is slightly suppressed. As a result, a cylindrical magnet for a motor rotor can be manufactured without torque unevenness and torque deterioration of the motor.
[0035]
When the molding is performed as described above, the magnetic field generated by the horizontal magnetic field vertical molding device is preferably 0.5 to 12 kOe. The reason why the magnetic field generated by the horizontal magnetic field vertical shaping apparatus is determined as described above is that when the magnetic field is large, the core 5a in FIG. 3A saturates and becomes close to the state shown in FIG. The magnetic field is preferably 12 kOe or less, since the orientation of the magnetic field does not become the radial orientation. When a ferromagnetic core is used, the magnetic flux concentrates on the core, so that a magnetic field larger than the magnetic field generated by the coil is obtained around the core. However, if the magnetic field is too small, a magnetic field sufficient for orientation cannot be obtained even around the core, so that the magnetic field is preferably 0.5 kOe or more. As described above, the magnetic flux gathers around the ferromagnetic material and the magnetic field increases, so the magnetic field generated by the horizontal magnetic field vertical shaping device here refers to the magnetic field or the ferromagnetic core at a place sufficiently away from the ferromagnetic material. It means the value of the magnetic field when measured after removal. Therefore, it is more preferable that the pressure be 1 to 10 kOe.
[0036]
Furthermore, in the present invention, in a vertical magnetic field vertical molding apparatus as shown in FIG. 2, a non-magnetic material is added to a die material of a molding die for a cylindrical magnet by a total angle of 20 ° or more and 180 ° or less, particularly 30 to 120 °. It is preferable to arrange at least one or more over the region.
[0037]
FIG. 5 shows a non-magnetic material (for example, a non-magnetic super hard material) 10 as a die material of a molding die for a radial cylindrical magnet in a vertical magnetic field vertical molding apparatus, and a region of an angle θ = 30 ° (30 out of 360 ° of a die cylinder 360 °). FIG. 2 shows a vertical magnetic field vertical shaping apparatus in which two vertical magnetic fields are arranged symmetrically in a region corresponding to (°). The lines of magnetic force near the nonmagnetic material are bent toward the ferromagnetic material. In particular, it is bent in the direction of the ferromagnetic material edge existing at the boundary between the nonmagnetic material and the ferromagnetic material. Since the magnet powder is oriented in the direction of the line of magnetic force, the desired magnet can be obtained. If the non-magnetic body arrangement angle at this time is less than 20 °, the effect of bending the lines of magnetic force is small, and in addition, the region where the orientation direction is inclined by 30 ° or more with respect to the radial direction is reduced, and the effect of suppressing cracking is small. On the other hand, when the angle is larger than 180 °, the radial orientation is hindered, and the magnet does not become a target.
In this case, in FIG. 5, 1 is a molding machine base, 3 is a die, 4 is a core, and 8 is a charged magnet powder, as in the case of FIG. The material other than the non-magnetic material 10 in the die 3 is formed of a ferromagnetic material of 5 kG or more. Further, the core material can be formed of a ferromagnetic material of 10 kG or more.
[0038]
By the way, when at least a part, preferably the whole, of the core 5a of the mold is formed of a ferromagnetic material having a saturation magnetic flux density of 5 kG or more, and the horizontal magnetic field vertical molding is performed as described above, in this method, the orientation by the coil is used. In a direction that is 90 ° with respect to the magnetic field direction, radial orientation may not be achieved. When there is a ferromagnetic substance in the magnetic field, the magnetic flux tends to enter the ferromagnetic substance perpendicularly and is attracted to the ferromagnetic substance, so that the magnetic flux density increases in the direction of the magnetic field of the ferromagnetic substance and decreases in the vertical direction. I do. For this reason, when the ferromagnetic core is arranged in the mold, a good orientation is obtained by the strong magnetic field in the magnetic field direction of the ferromagnetic core in the filled magnet powder, and the orientation is not so much in the vertical direction. To compensate for this, a good magnet can be obtained by rotating the magnet powder relatively to the magnetic field generated by the coil and re-orienting the incompletely oriented part with a magnetic field part having a strong magnetic field direction.
[0039]
Here, as a method of rotating the magnet powder relatively to the magnetic field generated by the coil, the following (i) to (v)
(I) rotating the magnet powder by a predetermined angle in the circumferential direction of the mold while applying a magnetic field;
(Ii) After applying the magnetic field, rotate the magnet powder by a predetermined angle in the circumferential direction of the mold, and then apply the magnetic field again.
(Iii) rotating the magnetic field generating coil with respect to the magnet powder by a predetermined angle in the circumferential direction of the mold during application of the magnetic field;
(Iv) After applying the magnetic field, rotate the magnetic field generating coil by a predetermined angle in the circumferential direction of the mold with respect to the magnet powder, and then apply the magnetic field again.
(V) Two or more pairs of magnetic field generating coils are arranged, and one pair of coils applies a magnetic field, and then another coil pair applies a magnetic field.
Of at least one of the above operations is performed once or repeatedly.
[0040]
As for the rotation of the charged magnet powder, as shown in FIG. 6, if the magnet powder can be rotated relatively to the direction of the magnetic field generated by the coil, any one of the coil 2, the core 5a, the die 3, and the punches 6, 7 is used. It may be rotated. In particular, when the filled magnet powder is rotated after the application of the magnetic field, if the residual magnetization of the ferromagnetic core or the magnet powder is at least 50 G, particularly 200 G or more, the magnet powder is magnetically interposed between the magnetic powder and the ferromagnetic core. Since an attractive force is generated, the magnet powder can be rotated only by rotating the ferromagnetic core.
[0041]
The rotation angle is appropriately selected, but when the initial position is set to 0 °, the rotation is preferably performed in the range of 10 to 170 °, particularly 60 to 120 °, typically around 90 °, while applying a magnetic field. In this case, the magnetic field is gradually rotated by a predetermined angle, and when the magnetic field is rotated after the application of the magnetic field, the magnetic field is applied again after the rotation by the predetermined angle.
[0042]
In the present invention, the molding is performed as described above. Otherwise, an orientation magnetic field is applied to the magnet powder by a normal vertical molding method, and the general molding pressure is 0.5 to 2.0 t / cm. ² And then subjected to sintering, aging, processing, etc., to obtain a sintered magnet.
[0043]
The magnet powder is not particularly limited, and is suitable for producing an Nd-Fe-B-based cylindrical magnet, as well as producing ferrite magnets, Sm-Co-based rare earth magnets, various bond magnets, and the like. In any case, the molding is performed using an alloy powder having an average particle size of 0.1 to 100 μm, particularly 0.3 to 50 μm.
[0044]
In the present invention, the outer peripheral surface of the thus obtained cylindrical magnet is multipolarly magnetized. Here, FIG. 7 illustrates a state in which the cylindrical magnet 21 is magnetized using the magnetizer 22. Reference numeral 23 denotes a magnetic pole tooth of the magnetizer, and reference numeral 24 denotes a coil of the magnetizer.
[0045]
FIG. 11 shows the surface magnetic flux density when the radial-like radially oriented cylindrical magnet manufactured by the horizontal magnetic field vertical molding according to the present invention was subjected to six-pole magnetization by the magnetizer of FIG. FIG. 12 is a surface magnetic flux density diagram when six-pole magnetization is performed on a radially oriented cylindrical magnet made by a conventional manufacturing method using the magnetizer of FIG. When a radially oriented cylindrical magnet is manufactured by a conventional horizontal magnetic field vertical molding method, and six-pole magnetization is performed so that the orientation magnetic field direction is N and S poles, the surface magnetic flux density is large in A and D in the orientation direction, A small surface magnetic flux density is obtained in the B, C, E, and F orientation directions that are close to a direction forming an angle of 90 ° with the orientation direction. In addition, the magnetization width varies greatly depending on the direction, even though the magnetization is performed using the magnetization tool having the same angle width. On the other hand, in the product of the present invention, the peak values of B, C, E, and F show an increase, and the magnetization width at the point where the surface magnetic flux becomes 0 becomes almost constant. However, B, C, E, and F have sharper shapes at the peak positions than those of A and D. Since the amount of magnetic flux is larger as the peak area is larger, B, C, E, and F are smaller than A and D. Variations in the amount of magnetic flux between the poles result in uneven rotation when assembled into the motor, which causes vibration and noise. Therefore, by reducing the variation in the amount of magnetic flux between the poles, smooth and smooth rotation can be performed.
[0046]
FIG. 10 shows a plan view of a three-phase motor having nine stator teeth (stator teeth). In the three-phase motor 30, the stator teeth 31 of α, β, and γ are arranged in the order of α, β, and γ, and the wiring is connected while winding the stator teeth in a coil shape, and is connected to the input lines of the motor as U, V, and W phases. Become. A current flows through the U, V, and W phases to generate a magnetic field in the coil 32, and the motor rotates by the repulsive and attractive forces acting between the magnetic field generated by the coil and the cylindrical magnet 21. Each of UV, VW, and WU surrounds one third of the total number of stator teeth. When a current flows through UV, a magnetic field is generated from α of the stator core. A magnetic field is generated in β by VW and in γ by WU. FIG. 10 shows a three-phase motor having such a stator having nine teeth, in which a radially oriented cylindrical magnet 21 magnetized to six poles is incorporated. In the drawing, reference numeral 33 denotes a motor rotor shaft.
[0047]
In the figure, UV (α) is located at the center of the pole of the magnet, and becomes the peak of the motor torque. At this time, the poles which act on UV (α) and generate a rotational force are A, C, and E poles, and the A pole is an orientation magnetic field direction pole, and has a large amount of magnetic flux. And the magnetic flux amount is small. Next, the magnet rotates, and the D, F, and B poles approach UV (α). The D pole is a pole in the direction of the aligning magnetic field and has a large amount of magnetic flux. F and B are poles located at an angle deviating from the direction of the aligning magnetic field and have a small amount of magnetic flux. However, since it has nine teeth which are 3/2 times the number of magnet poles 6, the amount of magnetic flux linked to the U-V (α) coil is equal to the sum of the A, C, and E poles, and D, The sum of the F and B poles is always equal. This relationship is the same in VW (β) and WU (γ). In this case, when the number of magnetized poles of the cylindrical magnet is k (k is a positive even number of 4 or more), the number of teeth of the stator combined with the cylindrical magnet is 3k · j / 2 (j is a positive integer of 1 or more). In particular, as described above, the combination of the number of magnet poles and the number of teeth of the motor stator is k = 6, the number of teeth is 3k · j / 2 = 9 (k = 6, j = 1). ), The magnets have poles in the direction of the orientation magnetic field and poles deviated from the direction of the orientation magnetic field. Obtainable. Here, k is preferably an even number of 50 or less, more preferably 40 or less, and j is preferably an integer of 10 or less, more preferably 5 or less. If the number k of poles is too large, the width of one pole is reduced, and the pole may not be clearly defined in the direction perpendicular to the direction of the alignment magnetic field.
[0048]
When the number of stator teeth is 3 m (m is a positive integer of 2 to 33) with respect to the number of magnet poles 2n (n is a positive integer of 2 to 50), the above relationship is always maintained. A motor without rotation unevenness can be obtained. However, 2n ≠ 3m. In particular, a motor having excellent motor characteristics without rotation unevenness can be produced particularly when the radially oriented cylindrical magnet is multipolar magnetized and the number of stator teeth is 3n times the number of magnetized poles.
[0049]
In the case where the multi-pole magnetization is performed on the cylindrical magnet according to the present invention, the magnetization and magnetic properties in the vicinity of the gap are low as compared with the case where the multi-pole magnetization is performed on the radial anisotropic ring magnet. Although the change in the gap between the poles is smooth and the cogging torque of the motor is small, the cogging torque can be further reduced by skew magnetizing or skewing the stator teeth. If the skew angle of the cylindrical magnet and the stator teeth is less than 1/10 of the angle of one pole of the cylindrical magnet, the effect of lowering the cogging torque due to the skew magnetization is small, and is larger than two thirds of the angle of one pole of the cylindrical magnet. Therefore, the skew angle is preferably 1/10 to 2/3 of the angle of one pole of the cylindrical magnet, and more preferably 1/10 to 2/5.
It should be noted that the permanent magnet motor of the present invention can be manufactured as a known configuration except for the configuration described above.
[0050]
In this case, FIG. 7 shows a case in which the orientation direction of the cylindrical magnet is rotated by 90 ° with respect to FIG. 8 to perform magnetization. As shown in FIG. 9, the boundary between the N pole and the S pole of the cylindrical magnet is It is preferable that it is within ± 10 ° with respect to the central part 40 of the part oriented in a direction inclined ± 30 ° or more with respect to the radial direction. Then, it is possible to circumferentially magnetize the multipole in the circumferential direction so as to provide a boundary between the N pole and the S pole at equal intervals in the circumferential direction from the boundary between the N pole and the S pole thus set. preferable. On the other hand, compared with the magnetization according to FIG. 8, in the magnetization according to FIG. 7, since the portion deviated from the radial direction is shared by four poles (two poles on each side), cogging is small and the torque increases.
[0051]
FIG. 8 is a schematic diagram illustrating a state in which the orientation direction of the cylindrical magnet is rotated by 90 ° with respect to FIG. 7 to perform the magnetization. In FIG. 8 in which the orientation direction is rotated by 90 ° with respect to FIG. 7 to perform six-pole magnetization, a relatively large amount of magnetic flux is obtained from the B, C, E, and F poles near the orientation magnetic field direction. Accordingly, the amount of magnetic flux is small in a portion perpendicular to the orientation direction of the A and D poles. When the magnets magnetized in FIGS. 7 and 8 are stacked in two stages and magnetized at a 90 ° offset to form a rotor magnet for a motor, the large magnetic fluxes A and D magnetized in FIG. 7 are magnetized in FIG. In this case, the amount of magnetic flux is small. Therefore, when combined, the amount of magnetic flux is slightly small in the magnetization shown in FIG. 7, but is relatively large in the magnetization shown in FIG. 8 for the B, C, E, and F poles. And the magnetic flux amount is almost the same. For this reason, by reducing the variation in the amount of magnetic flux between the poles, smooth and even rotation can be performed.
[0052]
Similarly, a cylindrical magnet having a radial-like orientation manufactured by a horizontal magnetic field vertical molding device is sliced and divided into two equal parts in the cylindrical axis direction, and the other is gradually rotated to perform stacking, Initially, the magnetization is performed in the arrangement shown in FIG. 7, but the direction is gradually changed, and after 90 ° rotation, the magnetization is performed in the arrangement shown in FIG. When this is rotated one after another to 90 ° and stacked, and then magnetized, the total magnetic flux gradually decreases as the rotation angle increases in the A and D poles, and the B, C, E and F poles Then, the total magnetic flux increases.
[0053]
Thus, by stacking two or more radial-like radially oriented cylindrical magnets manufactured by the molding machine in the axial direction and performing multipolar magnetization, the variation in the amount of magnetic flux between the poles can be reduced. Thus, uneven torque when used as a motor can be suppressed. The upper limit of the number of layers is not particularly limited, but is preferably about 10 steps.
[0054]
The orientation direction of the divided magnets is relatively rotated by a predetermined angle and stacked in multiple stages (two or more stages) to perform multi-polar magnetization, thereby making the variation in the magnetic flux amount between the orientation direction and the direction perpendicular thereto uniform. In addition, variations in the amount of magnetic flux between the poles can be reduced. At this time, it is preferable to perform multi-pole magnetization by shifting the orientations of the magnets to be stacked by 180 / i ° (i is the number of stacked magnets) at different angles.
[0055]
The number of divisions is set to i = n / 2 (n is the number of poles) in order to uniformly distribute the orientation direction to each pole. Thus, a portion having a small amount of magnetic flux can be uniformly distributed to each pole, and these are stacked at an angle shifted by 180 / i °, and the total magnetic flux of each pole can be equalized by multi-pole magnetization.
[0056]
Here, n is a positive integer of 4 to 50. When n is large, the gap between the magnetized poles is narrowed, and it becomes difficult to sufficiently magnetize. Therefore, n is particularly preferably 4 to 30.
[0057]
In addition, i is a positive integer of 2 to 10, and when i is large and the number of stacks is large, the cost becomes high.
[0058]
Multi-pole magnetization of a cylindrical magnet with unidirectional anisotropy using a horizontal magnetic field vertical shaping device is more magnetizable near the gap than when multi-polar magnetization is applied to a radially anisotropic ring magnet. Also, since the magnetic characteristics are low, the change of the magnetic flux density between the poles is smooth, and the cogging torque of the motor is small. The cogging torque can be further reduced by skew-magnetizing the magnet or skewing the stator teeth.
[0059]
The skew angle is less than 1/10 of the angle of one pole of the magnet (360 / n °) for both the magnet stator and the effect of lowering the cogging torque due to the skew magnetization is small. Therefore, the skew angle is preferably 1/10 to 2/3 of the angle of one pole of the magnet.
[0060]
As shown in FIG. 10, for example, the permanent magnet type motor of the present invention may incorporate the above-mentioned multi-stage long multi-pole magnetized cylindrical magnet rotor as a rotor into a motor, particularly a motor having a plurality of stator teeth. In this case, the configuration of the motor having the stator teeth may be a known configuration.
[0061]
【The invention's effect】
The radially anisotropic sintered magnet of the present invention has excellent magnet properties without cracks and cracks during sintering and aging cooling even in a shape having a small inner / outer diameter ratio.
[0062]
【Example】
Hereinafter, the present invention will be described specifically with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.
[0063]
[Example 1]
Nd, Dy, Fe, Co, M (M is Al, Si, Cu) having a purity of 99.7% by weight and B having a purity of 99.5% by weight are used for Nd. ₂₉ Dy _2.5 Fe ₆₄ Co ₃ B ₁ Al _0.2 Cu _0.1 Si _0.2 Was melt-cast in a vacuum melting furnace to produce an ingot. The ingot was coarsely pulverized with a jaw crusher and a brown mill, and further jet milled in a nitrogen stream to obtain a fine powder having an average particle size of 3.5 μm. This powder was subjected to 0.5 t / cm in a magnetic field of 8 kOe by a horizontal magnetic field vertical forming apparatus having a ferromagnetic (S50C: Fe steel) core having a saturation magnetic flux density of 20 kG. ² At a molding pressure of At this time, the packing density of the magnet powder was 25%. This compact was sintered in Ar gas at 1090 ° C. for 1 hour, followed by aging heat treatment at 580 ° C. for 1 hour. Thereafter, processing was performed to obtain a cylindrical magnet of φ30 mm × φ25 mm × L30 mm. The cylindrical magnet was magnetized into six poles by the magnetizer shown in FIG. 7, and a motor was prepared in which the magnetized magnet was incorporated into a stator having the same height as the magnet and having the configuration shown in FIG. A ferromagnetic core serving as a motor shaft is inserted and bonded to the inner diameter of the magnet. The copper fine wire was wound 150 turns for each tooth. The induced voltage when the motor was rotated at 1000 rpm and the magnitude of the torque ripple with a load meter when the motor was rotated at 1 to 5 rpm were measured.
[0064]
[Example 2]
The magnitude of the induced voltage and the torque ripple when the magnet obtained in the same manner as in Example 1 except that the magnet was magnetized by the magnetizing arrangement shown in FIG. 8 and incorporated in a motor were measured. Table 1 shows the results.
[Table 1]

[0065]
[Example 3]
A ferromagnetic material (SK5: Fe steel) having a saturation magnetic flux density of 18 kG occupying an area of 60% of the core cross-sectional area is arranged concentrically with the outer periphery of the core, and the rest is made of a nonmagnetic material. The cylindrical magnet produced in the same manner as in Example 1 was incorporated into a motor, and the motor characteristics were measured.
[0066]
[Example 4]
Using the same molding machine as in Example 1, the generated magnetic field was set to 6 kOe, and the other conditions were the same as those in Example 1 to produce a magnet, and the magnet was incorporated into the motor and the motor characteristics were measured.
[0067]
[Comparative Example 1]
Using the same magnet powder as in Example 1, using a vertical magnetic field vertical molding apparatus shown in FIG. 2, the magnetic field generated by the coil was set to 20 kOe, the magnet powder filling depth was set to 30 mm, and the molded body after being molded in the magnetic field was moved downward. Then, a magnet powder of 30 mm was placed on the compact in the same manner as above, and the magnet after compacting in a magnetic field was subjected to aging under the same conditions as in Example 1 to obtain a cylindrical magnet of φ30 mm × φ25 mm × L30 mm. This was incorporated into a motor and the motor characteristics were measured.
[0068]
[Comparative Example 2]
A magnet was manufactured under the same conditions as in Example 1 except that a non-magnetic material (non-magnetic super-hard material WC-Ni-Co) was used for the core material, and the magnet was assembled into a motor and the motor characteristics were measured.
[0069]
[Comparative Example 3]
Using a molding machine provided with a ferromagnetic material (magnetic superhard material WC-Ni-Co) core having a saturation magnetic flux density of 2 kG, a magnet was manufactured under the same conditions as in Example 1 except for the above, and the motor characteristics were measured. .
[0070]
[Example 5]
As shown in FIG. 5, two non-magnetic materials (non-magnetic super-hard material WC-Ni-Co) are arranged so as to be symmetrical at a portion of the die at an angle of 30 ° (total 60 °), and the other are comparative examples. A magnet was manufactured under the same conditions as in Example 1, and the motor characteristics were measured in the same manner.
[0071]
The volume (alignment disorder volume) of a portion inclined by 30 ° or more with respect to the radial orientation was calculated by polarization microscope observation, and is shown in Table 2. In addition, the number of cracks when 100 cylindrical magnets are manufactured under each condition is also described.
[0072]
[Table 2]

[0073]
From Table 2, it can be seen that the embodiment is effective for mass production of a magnet having excellent characteristics as a magnet for a motor because a large electromotive force is obtained, torque ripple is small, and no crack is generated.
[0074]
13, 14 and 15 show the results of observation of the magnet produced under the conditions of Example 4 under a polarizing microscope. That is, FIGS. 13, 14, and 15 show magnets manufactured by a horizontal magnetic field vertical forming apparatus using a ferromagnetic material as a core, and the magnets in the directions of 30 °, 60 °, and 90 ° with respect to the orientation magnetic field direction. As can be seen from these figures, the cylindrical magnet according to the present invention has a deviation from the radial direction of 30 ° with respect to the direction of the orientation magnetic field for the first time in the direction of 60 ° with respect to the orientation magnetic field direction. It can be seen that it is shifted.
[0075]
[Examples 6 to 9, Reference Example 1]
Nd, Dy, Fe, Co, M (M is Al, Si, Cu) having a purity of 99.7% by weight and B having a purity of 99.5% by weight are used for Nd. ₂₉ Dy _2.5 Fe _63.8 Co ₃ B ₁ Al _0.3 Si _0.3 Cu _0.1 Was melt-cast in a vacuum melting furnace to produce an ingot. The ingot was coarsely pulverized with a jaw crusher and a brown mill, and further jet milled in a nitrogen stream to obtain a fine powder having an average particle size of 3.5 μm. This powder was orientated in a magnetic field of 4 kOe generated by a coil by a horizontal magnetic field vertical forming apparatus having a ferromagnetic core made of iron having a saturation magnetic flux density of 20 kG as shown in FIG. The coil was rotated 90 ° and then again oriented in a 4 kOe magnetic field, 1.0 t / cm ² At a molding pressure of
[0076]
As Example 7, after orienting in a magnetic field of 4 kOe generated by the coil with a horizontal magnetic field vertical shaping device, the die, the core and the punch were rotated by 90 °, and then similarly oriented again in a magnetic field of 4 kOe, 1.0t / cm ² The molding was performed in the same manner as in Example 6, except that the molding was performed at a molding pressure of.
[0077]
In Example 8, after the core was oriented in a magnetic field of 4 kOe generated by a coil by a horizontal magnetic field vertical shaping device, the core having a residual magnetization of 4 kG was rotated by 90 °. The residual magnetization of the magnet powder at this time was 800G. Then, it is similarly oriented again in a magnetic field of 4 kOe, and then 1.0 t / cm ² The molding was performed in the same manner as in Example 6, except that the molding was performed at a molding pressure of.
[0078]
These compacts were sintered in Ar gas at 1090 ° C. for 1 hour, and subsequently subjected to aging heat treatment at 580 ° C. for 1 hour. Thereafter, processing was performed to obtain a cylindrical magnet of φ24 mm × φ19 mm × L30 mm. In addition, using the same magnet powder as the cylindrical magnet, 1.0 t / cm in a magnetic field of 12 kOe using a horizontal magnetic field vertical molding device. ² , Sintered at 1090 ° C. for 1 hour in Ar gas, and subsequently heat-treated at 580 ° C. for 1 hour. The characteristics of the block magnet produced under the same conditions as the present cylindrical magnet are as follows: Br: 12 0.5 kG, iHc: 15 kOe, (BH) max: 36 MGOe. A motor in which the above-mentioned cylindrical magnet is skew-magnetized at 6 poles and 20 ° by a magnetizing machine shown in FIG. 7 and the magnetized magnet is incorporated in a stator having the same height as the magnet and having a configuration shown in FIG. Was prepared. In addition, the induced voltage when the motor of the above example was rotated at 5000 rpm and the magnitude of the torque ripple by a load meter when the motor was rotated at 5 rpm were measured. Further, the cylindrical magnet obtained by molding, sintering, and heat treatment in the same manner as described above was magnetized by the magnetizer shown in FIG. 8, incorporated in a motor, and measured for induced voltage and torque ripple (Example 8a). Table 3 shows the difference between the maximum value of the absolute value of the induced voltage and the maximum value and the minimum value of the torque ripple.
[0079]
As Example 9, using the same horizontal magnetic field and vertical forming apparatus as in Example 6, orientation was performed while rotating 90 ° in a magnetic field of 12 kOe, and 1.0 t / cm ² At a molding pressure of Otherwise, the motor characteristics of the motor using the magnet produced in the same manner as in Example 6 were measured.
[0080]
On the other hand, as Reference Example 1, when oriented in a magnetic field of 4 kOe in Example 6, 1.0 t / cm ² At a molding pressure of Otherwise, the motor characteristics of the motor using the magnet produced in the same manner as in Example 6 were measured. Table 3 shows the results.
[0081]
[Table 3]

[0082]
From Table 3, it can be seen that the induced voltage corresponding to the torque is greatly improved in the example compared to the reference example, and that the present invention is an excellent method as a method for manufacturing a motor magnet.
[0083]
The result of measuring the surface magnetic flux of the magnetized rotor magnet of Example 6 is the same as that shown in FIG. 11, where each pole is uniform and the area of the pole is large. Can be uniformly generated.
[0084]
[Example 10]
Nd, Dy, Fe, Co, M (M is Al, Si, Cu) having a purity of 99.7% by weight and B having a purity of 99.5% by weight are used for Nd. ₂₉ Dy _2.5 Fe ₆₄ Co ₃ B ₁ Al _0.2 Si _0.2 Cu _0.1 Was melt-cast in a vacuum melting furnace to produce an ingot. The ingot was coarsely pulverized with a jaw crusher and a brown mill, and further jet milled in a nitrogen stream to obtain a fine powder having an average particle size of 3.5 μm. This powder was subjected to 1.0 t / cm in a magnetic field of 10 kOe by a horizontal magnetic field vertical forming apparatus shown in FIG. 1 having a ferromagnetic core made of Fe having a saturation magnetic flux density of 20 kG. ² At a molding pressure of This compact was sintered in Ar gas at 1090 ° C. for 1 hour, and subsequently heat-treated at 580 ° C. for 1 hour. Thereafter, processing was performed to obtain a cylindrical magnet of φ30 mm × φ25 mm × L30 mm. Using the same magnet powder as the cylindrical magnet, 1.0 t / cm in a magnetic field of 10 kOe using a horizontal magnetic field vertical molding device ² , Sintered at 1090 ° C. for 1 hour in Ar gas, and then heat-treated at 580 ° C. for 1 hour. The properties of the block magnet produced under the same conditions as the present cylindrical magnet are as follows: 13.0 kG, iHc: 15 kOe, (BH) max: 40 MGOe.
[0085]
The above-mentioned radially-oriented cylindrical magnet was magnetized by a magnetizer into six poles, and a motor was manufactured in which the magnetized magnet was incorporated in nine stators having the same height as the magnet and having the configuration shown in FIG. . A ferromagnetic core serving as a motor shaft is inserted and bonded to the inner diameter of the magnet. The copper wire was wound 100 turns for each tooth. The amount of magnetic flux between the U and V phases was measured using a flux meter.
[0086]
[Comparative Example 4]
The same thin copper wire as in Example 10 was wound 100 times around only one of the stator teeth, and the amount of magnetic flux was measured with a flux meter. Table 4 shows the peak values when the magnet makes one rotation. As shown in the table, in the comparative example, although the amount of magnetic flux due to the peak is as large as about 1.5 times as large as the small peak, the peak value is hardly changed in the tenth embodiment.
[0087]
[Example 11]
A ferromagnetic material having a saturation magnetic flux density of 18 kG occupying an area of 60% of the core cross-sectional area is arranged concentrically with the outer periphery of the core, and the rest uses a core made of a nonmagnetic material. The amount of magnetic flux between the U and V phases of the produced motor was measured.
[0088]
[Comparative Example 5]
The amount of magnetic flux between the U and V phases of a motor manufactured in the same manner as in Example 10 except that a non-magnetic material (non-magnetic super-hard material WC-Ni-Co) was used for the core material was measured.
[0089]
[Comparative Example 6]
The amount of magnetic flux between the U and V phases of a motor manufactured in the same manner as in Example 10 except that the saturation magnetic flux density of the ferromagnetic core made of Fe was set to 2 kG was measured. The amount of magnetic flux between the U and V phases of the motor when it was arranged was measured using a flux meter.
Table 4 shows the results.
[0090]
[Table 4]

[0091]
[Example 12]
The induced voltage when the motor of Example 10 was rotated at 1000 rpm and the magnitude of the torque ripple by a load meter when the motor was rotated at 1 to 5 rpm were measured. Table 5 shows the difference between the maximum value of the absolute value of the induced voltage and the maximum value and the minimum value of the torque ripple. From Table 5, it can be seen that the present motor has a sufficient amount of induced voltage in use and has sufficiently small torque ripple.
[0092]
Example 13
When magnetizing the radially oriented cylindrical magnet of the tenth embodiment, the skew angle is set to 20 ° which is 1/3 of the angle of one pole of the magnet, and the magnet is incorporated in the motor of the tenth embodiment. Table 5 shows the measured values of the induced voltage and the torque ripple in the same manner as in Example 12. From Table 5, it can be seen that the amount of torque ripple is even smaller than the product without skew, and the reduction in induced voltage is slight.
[0093]
[Reference Example 2]
When magnetizing the radially oriented cylindrical magnet of the tenth embodiment, skew magnetizing is performed at 50 degrees, which is 5/6 of the angle of one pole of the skew angle magnet, and the magnet is incorporated in the motor of the tenth embodiment. Table 5 shows the measured values of the induced voltage and the torque ripple in the same manner as in Example 12. From Table 5, it can be seen that although the amount of torque ripple is smaller than that of the product without skew, the induced voltage is greatly reduced and may not be suitable for practical use.
[0094]
[Example 14]
A radially oriented cylindrical magnet is magnetized in the same manner as in Example 10, and is incorporated into a motor having the same dimensions as Example 10 having a stator tooth having a skew angle of 20 ° which is 1/3 of the angle of one pole of the magnet. Table 5 shows the measured values of the induced voltage and the torque ripple in the same manner as in Example 12. From Table 5, it can be seen that the amount of torque ripple is even smaller than that of the product without skew, and the induced voltage is slightly reduced.
[0095]
[Table 5]

[0096]
[Example 15]
Nd, Dy, Fe, Co, M (M is Al, Si, Cu) having a purity of 99.7% by weight and B having a purity of 99.5% by weight are used for Nd. ₂₉ Dy _2.5 Fe ₆₄ Co ₃ B ₁ Al _0.2 Si _0.2 Cu _0.1 Was melted and cast in a vacuum melting furnace to produce an ingot. The ingot was coarsely pulverized with a jaw crusher and a brown mill, and further jet milled in a nitrogen stream to obtain a fine powder having an average particle size of 3.5 μm. This powder was subjected to 1.0 t / cm in a magnetic field of 6 kOe in a horizontal magnetic field vertical forming apparatus as shown in FIG. 1 in which a ferromagnetic core made of Fe having a saturation magnetic flux density of 20 kG was arranged. ² At a molding pressure of This compact was sintered in Ar gas at 1090 ° C. for 1 hour, and subsequently heat-treated at 580 ° C. for 1 hour. Thereafter, processing was performed to obtain a cylindrical magnet having an outer diameter of 30 mm, an inner diameter of 25 mm, and a thickness of 15 mm.
[0097]
In Example 15, the produced cylindrical magnets were stacked with the orientation directions shifted by 60 °, and the magnet orientation directions of the first stage were arranged so as to have the relationship shown in FIG. Magnetization was performed in three stages.
[0098]
[Example 16]
In Example 16, the shift angle was set to 90 °, and six-pole magnetized two-stage stacking was performed as in Example 15.
[0099]
[Reference Example 3]
A cylindrical magnet having an outer diameter of 30 mm, an inner diameter of 25 mm, and a thickness of 30 mm was prepared under the same conditions as in Example 15 except that the height of the compact was changed and no stacking was performed, using the same magnet powder as in Example 15, and 6 poles were attached Made magnetism.
[0100]
[Example 17]
Using the same magnet powder as in Example 15, cylindrical magnets having an outer diameter of 30 mm, an inner diameter of 25 mm, and a thickness of 10 mm were produced under the same conditions, and the orientation was shifted by 60 ° and stacked in three stages. Each was arranged as shown in FIG. 7 and six-pole magnetization was performed. This is shown in FIG. The large arrows in the figure indicate the direction of the magnetic field during the orientation of each stage of the cylindrical magnet. Reference numeral 33 denotes a motor rotor shaft.
[0101]
In order to evaluate these magnets, a coil was prepared by winding a copper thin wire around a square having a width of 10.5 mm and a length of 30 mm for 50 turns. Move this coil away from the state in which it is in contact with the cylindrical magnet to a distance that is not affected by the magnetic force of the magnet. Show.
[0102]
[Table 6]

[0103]
[Examples 18, 19, Reference Example 4, Comparative Example 7]
FIG. 10 shows a plan view of a three-phase permanent magnet motor 30 having nine motor stator teeth 31. A motor was manufactured by incorporating a magnetized cylindrical magnet into a stator having the same height as the magnet. A ferromagnetic core serving as a motor shaft is inserted and bonded to the inner diameter of the cylindrical magnet. A fine copper wire was wound around each tooth for 150 turns. The motor was rotated at 1000 rpm, the absolute value of the induced voltage at this time was maximum, and the motor was rotated at 1 to 5 rpm, and the magnitude of the torque ripple was measured using a load meter.
[0104]
Here, in Example 18, as in Example 16, magnets were superposed in two stages at a shift angle of 90 °, and skew magnetization was performed at a skew angle of 20 °, which is １ ／ of the angle of one pole of the magnet. This magnet is built into a motor.
[0105]
In Example 19, a cylindrical magnet having the same dimensions as in Example 17 was used, and magnets were stacked in three stages at a shift angle of 60 ° and magnetized without skew as shown in FIG. It is incorporated into a motor having skew stator teeth that are 20 degrees, one third of the angle.
[0106]
In addition, a cylindrical magnet without stacking was used as Reference Example 4, and the core of the molding die was made of non-magnetic (non-magnetic super-hard material WC-Ni-Co) and placed in a molding machine. In the same manner as in Example 18, a magnet was produced, and this was assembled into a motor in the same manner as in Example 18, to obtain Comparative Example 7. These induced voltages and torque ripples were measured, and the maximum and minimum differences between the torque ripples and the induced voltages are shown in Table 7.
[0107]
From Table 7, it can be seen that each of the examples has an induced voltage that can withstand practical use and the torque ripple is sufficiently small, but that the reference example 4 has a large torque ripple. Comparative Example 7 has a low induced voltage and is not suitable for practical use.
[0108]
[Reference Example 5]
When magnetizing the radially-oriented cylindrical magnet of Example 18, the skew was magnetized at 50 ° which is 5/6 of the angle of one pole of the skew angle magnet, and this magnet was incorporated into the motor of FIG. The induced voltage and the torque ripple were measured in the same manner as described above.
[0109]
From Table 7, it can be seen that although the amount of torque ripple is small, the reduction in induced voltage is large and is not suitable for practical use.
[0110]
[Example 20, Reference example 6]
Using the Nd magnet alloy of Example 15, a uniaxially oriented ring magnet was manufactured by a horizontal magnetic field vertical forming method. The magnet has an outer diameter of 25 mm, an inner diameter of 20 mm, and a thickness of 15 mm. The magnet rotor was manufactured by stacking six stages while changing the orientation direction by 60 °, and magnetizing straight to six poles. This was incorporated into a 7 ° skew angle stator to form a motor.
[0111]
Further, as Reference Example 6, using the same magnet as in Example 20, the orientation direction was aligned in one direction, and the magnet was straightly magnetized to six poles to produce a magnet rotor. This was incorporated into a skewless stator to form a motor. In these, the torque ripple was measured together with the induced voltage.
[0112]
The results are as shown in Table 7. In Example 20, the torque ripple was greatly reduced as compared with Reference Example 6, and it was found that the effect of the magnet in the orientation direction dispersion according to the present invention was remarkable.
[0113]
[Table 7]

[Brief description of the drawings]
FIG. 1 is an explanatory view showing one embodiment of a horizontal magnetic field vertical shaping apparatus used when manufacturing a cylindrical magnet, wherein (a) is a plan view and (b) is a longitudinal sectional view.
FIGS. 2A and 2B are explanatory views showing a conventional vertical magnetic field vertical forming apparatus used when manufacturing a radially anisotropic cylindrical magnet, wherein FIG. 2A is a longitudinal sectional view, and FIG. It is sectional drawing of the A 'line.
FIG. 3 is an explanatory view schematically showing the state of magnetic lines of force when a magnetic field is generated in a horizontal magnetic field vertical shaping apparatus used when manufacturing a cylindrical magnet, wherein (a) shows the case of the shaping apparatus according to the present invention; b) shows the case of a conventional molding apparatus.
4A and 4B are explanatory views showing another embodiment of a horizontal magnetic field vertical shaping apparatus used when manufacturing a cylindrical magnet, wherein FIG. 4A is a plan view and FIG. 4B is a longitudinal sectional view.
5A and 5B are explanatory views showing a vertical magnetic field vertical forming apparatus in which a non-magnetic material is partially disposed in a die portion used when manufacturing a radially anisotropic cylindrical magnet, wherein FIG. FIG. 2B is an enlarged view of a portion B1 to B4 in FIG.
FIG. 6 is an explanatory view showing an example of a rotary horizontal magnetic field vertical forming apparatus, which is a forming apparatus used when manufacturing a cylindrical magnet.
FIG. 7 is a schematic diagram illustrating a state in which a cylindrical magnet is magnetized using a magnetizer.
FIG. 8 is a schematic diagram showing a state in which a cylindrical magnet is magnetized using a magnetizer, and shows a state in which the orientation direction of the cylindrical magnet is rotated by 90 ° with respect to FIG. 7 to perform the magnetization.
FIG. 9 is a plan view illustrating a boundary between an N pole and an S pole of a cylindrical magnet.
FIG. 10 is a plan view showing a three-phase motor in which a cylindrical magnet multipolarized into six poles is combined with nine stator teeth.
FIG. 11 is a diagram showing a surface magnetic flux density when six-pole magnetization is performed on an Nd—Fe—B-based cylindrical magnet produced by the horizontal magnetic field vertical shaping apparatus according to the present invention.
FIG. 12 is a diagram showing the surface magnetic flux density when six-pole magnetization is performed on an Nd—Fe—B-based cylindrical magnet produced by a conventional horizontal magnetic field vertical forming apparatus (using a nonmagnetic material as a core material). is there.
FIG. 13 is a micrograph showing the orientation of a magnet in a direction of 30 ° with respect to the orientation magnetic field of a magnet produced by a horizontal magnetic field vertical forming apparatus using a ferromagnetic material used as a core when manufacturing a cylindrical magnet. It is.
FIG. 14 is a micrograph showing the orientation of a magnet in a direction of 60 ° with respect to the orientation magnetic field of a magnet produced by a horizontal magnetic field vertical molding apparatus using a ferromagnetic material used as a core when manufacturing a cylindrical magnet. It is.
FIG. 15 is a micrograph showing the orientation of a magnet at 90 ° with respect to the orientation magnetic field direction of a magnet produced by a horizontal magnetic field vertical forming apparatus using a ferromagnetic material as a core when manufacturing a cylindrical magnet. It is.
FIG. 16 is a perspective view showing a rotor for a permanent magnet type motor of the present invention in which radially oriented cylindrical magnets are stacked in three stages shifted by 60 °.
[Explanation of symbols]
1 Molding machine stand
2 Orientation field coil
3 dice
4 core
5 core
5a core
5a 'Weak ferromagnetic hard metal part
6 Upper punch
7 Lower punch
8 Filled magnet powder
9 pole pieces
10 Dice non-magnetic material
11 Permendur
21 Cylindrical magnet
22 Magnetizer
23 Magnet pole teeth
24 magnetizer coil
30 three-phase motor
31 Stator teeth
32 coils
33 Motor rotor shaft

Claims (19)

A portion formed in a cylindrical shape and oriented in a direction inclined by 30 ° or more with respect to the radial direction contains 2% or more and 50% or less of the magnet volume, and the remaining portion of the magnet volume has a radial direction or an inclination of 30 ° with respect to the radial direction. A radially anisotropic sintered magnet characterized by being oriented less than. A ferromagnetic material having a saturation magnetic flux density of 5 kG or more is used for at least a part of a core of a molding die for a cylindrical magnet. A method for producing a radially anisotropic sintered magnet, characterized by applying and molding. 3. The method for producing a radially anisotropic sintered magnet according to claim 2, wherein the magnetic field generated by the horizontal magnetic field vertical shaping is 0.5 to 12 kOe. At least one non-magnetic material is arranged on a die material of a molding die for a cylindrical magnet over a region having a total angle of 20 ° or more and 180 ° or less, and a magnet powder filled in a mold cavity is magnetized by a vertical magnetic field vertical molding method. A method for producing a radially anisotropic sintered magnet, which comprises applying a magnetic field to a powder to form the powder. A ferromagnetic material having a saturation magnetic flux density of 5 kG or more is used for at least a part of the material of the core of the molding die for cylindrical magnets. A method for producing a radially anisotropic magnet by applying and molding, comprising the following (i) to (v)
(I) rotating the magnet powder by a predetermined angle in the circumferential direction of the mold while applying a magnetic field;
(Ii) After applying the magnetic field, rotate the magnet powder by a predetermined angle in the circumferential direction of the mold, and then apply the magnetic field again.
(Iii) rotating the magnetic field generating coil with respect to the magnet powder by a predetermined angle in the circumferential direction of the mold during application of the magnetic field;
(Iv) After applying the magnetic field, rotate the magnetic field generating coil by a predetermined angle in the circumferential direction of the mold with respect to the magnet powder, and then apply the magnetic field again.
(V) Two or more pairs of magnetic field generating coils are arranged, and after one pair of coils applies a magnetic field, another coil pair performs at least one operation of applying a magnetic field. Manufacturing method of isotropic sintered magnet. 6. The radially anisotropic sintered magnet according to claim 5, wherein, when rotating the filled magnet powder, at least one of a core, a die, and a punch is rotated in a circumferential direction to rotate the filled magnet powder. Production method. 6. The magnetic powder according to claim 5, wherein when the magnetic powder is rotated after applying the magnetic field, the value of the residual magnetization of the ferromagnetic core or the magnetic powder is 50 G or more, and the magnetic powder is rotated by rotating the core in the circumferential direction. A method for producing the radially anisotropic sintered magnet described in the above. The method for manufacturing a radial anisotropic magnet according to any one of claims 5 to 7, wherein a magnetic field generated in the horizontal magnetic field vertical forming step is 0.5 to 12 kOe. In a permanent magnet motor in which a radially anisotropic cylindrical magnet is incorporated in a motor having a plurality of stator teeth, the cylindrical magnet has a saturation magnetic flux density of 5 kG or more in at least a part of a core material of a molding die for a cylindrical magnet. A radial anisotropic cylindrical magnet formed by applying an orientation magnetic field to a magnet powder by using a horizontal magnetic field vertical molding method with a magnet powder filled in a mold cavity using a ferromagnetic material having When the number of magnetic poles is 2n (n is a positive integer of 2 or more and 50 or less), the number of teeth of the stator combined with the cylindrical magnet is 3 m (m is a positive integer of 2 or more and 33 or less), and 2n ≠ A permanent magnet motor, which is magnetized to have multiple poles in the circumferential direction, having a length of 3 m. When the number of magnetic poles in the circumferential direction of the cylindrical magnet is k (k is a positive even number of 4 or more), the number of teeth of the stator combined with the cylindrical magnet is 3k · j / 2 (j is a positive integer of 1 or more). The permanent magnet motor according to claim 9, wherein the number is one. The boundary between the north pole and the south pole of the cylindrical magnet is within 10 degrees with respect to a central portion of a portion oriented in a direction inclined by 30 degrees or more with respect to the radial direction. Permanent magnet motor. The permanent magnet motor according to any one of claims 9 to 11, wherein the skew angle of the cylindrical magnet is 1/10 to 2/3 of the angle of one pole of the cylindrical magnet, and the multi-pole skew is magnetized. . The permanent magnet motor according to any one of claims 9 to 12, wherein the skew angle of the stator teeth is 1/10 to 2/3 of the angle of one pole of the cylindrical magnet. The permanent magnet motor according to any one of claims 9 to 13, wherein a magnet formed by setting the magnetic field generated by the horizontal magnetic field vertical shaping to 0.5 to 12 kOe is used. A ferromagnetic material having a saturation magnetic flux density of 5 kG or more is used as at least a part of the material of the core of the molding die for cylindrical magnets. The magnet powder filled in the mold cavity is subjected to an orientation magnetic field by a horizontal magnetic field vertical molding method. A multi-stage long multi-pole magnetized cylinder characterized in that a plurality of radially anisotropic cylindrical magnets formed by applying a voltage and produced by multi-polar magnetization are stacked in two or more stages in the axial direction. Magnet rotor. When the number of stacked cylindrical magnets is i (i is a positive integer of 2 or more and 10 or less), i pieces are stacked by shifting the same direction as the orientation magnetic field direction of each cylindrical magnet by an angle of 180 / i °. 16. The multi-stage long multi-pole magnetized cylindrical magnet rotor according to 15. 17. The multi-pole magnet according to claim 15, wherein when the number of poles of the multipole magnetization is n (n is a positive integer of 4 or more and 50 or less), the number i of stacks and the number n of poles have a relationship of i = n / 2. Multi-stage long multi-pole magnetized cylindrical magnet rotor. 16. An n-pole multipole magnetizing method for the outer peripheral surface of a cylindrical magnet, wherein the angle of one pole is 360 / n °, and skew magnetizing is performed at an angle of 1/10 to 2/3 of this angle. 18. The multi-stage long multi-pole magnetized cylindrical magnet rotor according to any one of claims 17 to 17. A permanent magnet motor using the multi-stage long multi-pole magnetized cylindrical magnet rotor according to any one of claims 15 to 18.

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