JP2004039822A - Permanent magnet, components for motors, and motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a permanent magnet without affecting equipment mounting a motor, in particular, the equipment such as a hard disk drive, and to provide components for the motors and the motor. <P>SOLUTION: The permanent magnet 1 has a substantially cylindrical magnet body 11, a substrate layer 13 formed on at least a part of the surface, and a coating layer 12 forming the outermost surface. The coating layer 12 is mainly composed of a polyparaxylene resin. In addition, when an average thickness of the coating layer 12 in the side of the inner peripheral face of a magnet body 11 is Di[μm] and an average thickness of the coating layer 12 in the side of the outer peripheral face of the magnet body 11 is Do[μm], relation of Di>Do is satisfied. The average thickness Di of the coating layer 12 in the side of the inner peripheral face of the magnet body 11 is 15-35 μm. The average thickness Do of the coating layer in the side of the outer peripheral face of the magnet body 11 is not more than 15 μm. A substrate layer 13 is preferably composed of a material containing at least one of an epoxy resin or a phenol resin. <P>COPYRIGHT: (C)2004,JPO

Description

【０１７３】
［永久磁石の評価］
＜発生ガス量の測定＞
また、サンプルＮｏ．１〜Ｎｏ．２０の各永久磁石について、以下のような条件で、発生ガス量の測定を行った。
【０１７４】
まず、サンプルＮｏ．１〜Ｎｏ．２０のそれぞれについて、各々５個ずつの永久磁石を用意した。これらの永久磁石に対して、純水超音波洗浄を行った。この純水超音波洗浄は、２５℃×５分間という条件で行った。その後、８０℃で３０分間乾燥した。
【０１７５】
次に、各サンプルの磁石（各々５個ずつ）を、それぞれ、容量１００ｍＬのヘッドスペース瓶に入れ、７０℃で１６時間加熱した。次に、Ｈｅガスをキャリアーガスとして１ｍＬ／分の流速で３０分間流し、流出してきたガスを捕集した。その後、捕集したガスを、ＧＣ−ＭＳ（ヒューレットパッカード社製：商品名「５８９０−５９７１Ａ」）で分析した。そして、得られた測定結果から、永久磁石の表面積１ｍ^２あたりの発生ガス量を求めた（測定限界２０μｇ／ｍ^２）。
【０１７６】
＜イオン量の測定＞
また、サンプルＮｏ．１〜Ｎｏ．２０の各永久磁石について、以下のような条件で、抽出イオン量の測定を行った。
【０１７７】
まず、サンプルＮｏ．１〜Ｎｏ．２０のそれぞれについて、各々５個ずつの永久磁石を用意した。これらの永久磁石に対して、純水超音波洗浄を行った。この純水超音波洗浄は、２５℃×３分間という条件で行った。その後８５℃で３０分間乾燥した。
【０１７８】
次に、８０℃、６０ｍＬの純水を用いて、各サンプルの永久磁石（各々５個ずつ）に対して、３０分間抽出操作を行った。次に、この水に対して、イオンクロマトアナライザー（横河電機社製：商品名「ＩＣ５００」）を用いて、Ｂｒ⁻、ＮＯ_Ｘ ⁻、Ｃｌ⁻、ＰＯ_４ ^３−、Ｆ⁻、ＳＯ_４ ^２−、ＮＨ_４ ^＋の各濃度を、分析、測定した。そして、得られた測定結果から、永久磁石の表面積１ｍ^２あたりのイオン抽出量の総量を求めた（測定限界５μｇ／ｍ^２）。
【０１７９】
＜圧環強度の測定＞
また、サンプルＮｏ．１〜Ｎｏ．２０の各永久磁石について、圧環強度を測定した。圧環強度の測定は、ＪＩＳ　Ｚ　２５０７に準じて行った。
【０１８０】
＜塩水噴霧試験＞
また、サンプルＮｏ．１〜Ｎｏ．２０の各永久磁石について、ＪＩＳ　Ｋ　５４０１に記載の方法に準拠して、２４時間暴露試験を実施した。
【０１８１】
その後、８倍顕微鏡下で、磁石表面の異なる１０箇所を観察し、視野内に変色が見られなかった場合には◎として評価した。また、一部変色が１〜２点確認された場合には○として評価した。また、変色が３点以上確認された場合には△として評価した。また、赤錆が１点以上確認された場合には×として評価した。
これらの結果を表２に示す。
【０１８２】
【表２】

【０１８３】
表２から明らかなように、サンプルＮｏ．１〜Ｎｏ．１７の永久磁石（いずれも本発明）では、発生ガス量が極めて少なく、いずれも測定限界以下であった。また、サンプルＮｏ．１〜Ｎｏ．１７の永久磁石（いずれも本発明）では、抽出イオン量が極めて少なく、４２ｍｇ／ｍ^２以下であった。これに対し、サンプルＮｏ．１８、Ｎｏ．１９の永久磁石（いずれも比較例）は、発生ガス量、抽出イオン量が多かった。
【０１８４】
また、圧環強度の測定では、サンプルＮｏ．１〜Ｎｏ．１７の永久磁石（いずれも本発明）が優れた機械的強度を有するものであることが確認された。これに対し、サンプルＮｏ．１８、Ｎｏ．１９の永久磁石（いずれも比較例）は、機械的強度に劣っていた。
【０１８５】
また、塩水噴霧試験においては、サンプルＮｏ．１〜Ｎｏ．１７の永久磁石（いずれも本発明）では、変色がほとんど見られず、良好な耐錆性を有していることが確認された。これに対し、サンプルＮｏ．１８、Ｎｏ．１９の永久磁石（いずれも比較例）では、変色や錆びがはっきりと認められた。
【０１８６】
また、サンプルＮｏ．１〜Ｎｏ．１７の永久磁石（いずれも本発明）について、外周面の１２箇所（永久磁石の外周面において、円筒の軸を中心に周方向に３０°ずつ分割した箇所）について、被覆層の厚さを測定した。その結果、膜厚のばらつきは、きわめて小さく、いずれも、±１．０％以下であった。
【０１８７】
（実施例２）
［ロータ（モータ用部品）の製造］
前記実施例１で製造したサンプルＮｏ．１〜Ｎｏ．２０の各永久磁石を用いて、以下のようにして、図４に示すようなロータ（モータ用部品）を製造した。
【０１８８】
まず、快削鋼材（ＳＵＭ２１）で構成された略円筒状部材を用意し、これに切削加工を施すことにより、ヨークを得た。このようにして得られたヨークの表面粗さＲａ（内表面）は、１．９μｍであった。また、ヨークの２０℃における熱膨張率（線膨張率）は、１１．７［×１０^−６Ｋ^−１］であった。
【０１８９】
次に、得られたヨークと永久磁石とを熱カシメにより接合した。
熱カシメによる接合は、以下のようにして行った。
【０１９０】
まず、加熱台上で、ヨークの温度が２００℃になるように加熱した。このような状態で、高さ方向の位置が決まる治具を用いて、ヨークの基端側から、その中空部に永久磁石を挿通した。なお、このときの永久磁石の温度は２０℃であった。
【０１９１】
その後、加熱台から冷却台に移動させ、永久磁石が挿通された状態のヨークを冷却し、その温度を２０℃にした。
【０１９２】
その結果、サンプルＮｏ．１〜Ｎｏ．１７、Ｎｏ．２０の永久磁石を用いたものでは、ヨークと永久磁石とが、強固に接合した接合体が得られた。また、サンプルＮｏ．１８、Ｎｏ．１９の永久磁石を用いたものでは、冷却に伴うヨークの収縮により、永久磁石に微小なひび割れを生じた。
【０１９３】
以上のようにして得られた永久磁石とヨークとの接合体を用いて、図４に示すようなロータ（モータ用部品）を得た。なお、ヨーク、ハブ、スリーブの構成材料としては、それぞれ、快削鋼（ＳＵＭ２１）、アルミニウム、真鍮を用い、ヨークとハブとの接合、ハブとスリーブとの接合は、いずれも、圧入により行った。
【０１９４】
各ロータについて、製造に用いたボンド磁石の寸法（室温（２０℃）における自然状態での寸法：外径×内径（先端部付近を除く）×高さ）、ヨークの寸法（室温（２０℃）における自然状態での寸法：外径×内径（先端部付近を除く）×高さ）、およびヨークの加熱状態での内径を表３に示す。
【０１９５】
【表３】

【０１９６】
［ロータの評価およびモータの製造］
上記のようにして製造された各ロータについて、島津製作所社製動釣合試験機（ＶＣ　００３Ｔ形）を用いて回転アンバランス量の測定を実施した。そのときの回転数は３６００ｒｐｍとした。
回転アンバランス量の測定結果を表４に示す。
【０１９７】
【表４】

【０１９８】
表４から、サンプルＮｏ．１〜Ｎｏ．１７によるロータ（いずれも本発明）では、回転アンバランス量が極めて小さいことがわかる。これに対し、サンプルＮｏ．１８〜Ｎｏ．２０によるロータ（いずれも比較例）では、回転アンバランス量が大きい。中でも、サンプルＮｏ．２０によるロータは、回転アンバランス量が極めて大きかった。
【０１９９】
次に、サンプルＮｏ．１〜Ｎｏ．２０によるロータを用いて、図５に示すようなモータを製造した。
【０２００】
このようにして得られた各モータについて、ステータのコイルへの通電操作（通電時間：３０秒間、最大回転数：７２００ｒｐｍ）を繰り返し行った。
【０２０１】
サンプルＮｏ．１〜Ｎｏ．１７によるモータ（いずれも本発明）では、駆動時の振動、騒音が比較的小さいものであったのに対し、サンプルＮｏ．１８〜Ｎｏ．２０によるモータ（いずれも比較例）では、駆動時の振動、騒音が大きかった。比較例のモータで、駆動時の振動、騒音が大きかったのは、被覆層の厚さが大きいためにロータのアンバランス量が大きくなっていたこと、熱カシメ時に永久磁石が欠損、破損したためにロータのアンバランス量が大きくなっていたことによるものであると考えられる。
【０２０２】
また、サンプルＮｏ．１８〜Ｎｏ．２０によるモータ（いずれも比較例）では、上記の通電操作の回数が約３００００回目に達する頃から振動、騒音（異音）がさらに激しいものとなった。
【０２０３】
上記の通電操作を５００００回行った後、各モータを分解した。分解した各モータからロータを取り出し、これらの各ロータについて、ＪＩＳ　Ｋ　５４０１に記載の方法に準拠して、２４時間暴露試験を実施した。
【０２０４】
その結果、サンプルＮｏ．１８、Ｎｏ．１９によるロータ（いずれも比較例）では、永久磁石周辺に、赤錆等による変色がはっきりと認められた。これに対し、サンプルＮｏ．１〜Ｎｏ．１７によるロータ（いずれも本発明）では、永久磁石の周辺には錆等による変色が認められなかった。
【０２０５】
（実施例３）
［ロータ（モータ用部品）の製造］
前記実施例１で製造したサンプルＮｏ．１〜Ｎｏ．２０の各永久磁石を用いて、以下のようにして、図４に示すようなロータ（モータ用部品）を製造した。
【０２０６】
まず、快削鋼材（ＳＵＭ２１）で構成された略円筒状部材を用意し、これに切削加工を施すことにより、ヨークを得た。このようにして得られたヨークの表面粗さＲａ（内表面）は、１．９μｍであった。また、ヨークの２０℃における熱膨張率（線膨張率）は、１１．７［×１０^−６Ｋ^−１］であった。
【０２０７】
次に、得られたヨークの中空部に、永久磁石を圧入した。永久磁石の圧入は、永久磁石がヨークに対して傾かないような位置出し治具を用いて、油圧プレスにより行った。このときの永久磁石とヨークとの相対的な移動速度（接近速度）は、５ｃｍ／秒であった。
【０２０８】
サンプルＮｏ．１〜Ｎｏ．１７の永久磁石を用いたものでは、圧入の操作を円滑に行うことができ、また、圧入により得られた永久磁石とヨークとの接合体は、永久磁石とヨークとが極めて強固に接合したものであった。また、サンプルＮｏ．１８の永久磁石を用いたものでは、圧入により接合しようと試みたところ、ボンド磁石の一部が削り取られた。また、サンプルＮｏ．１９の永久磁石を用いたものでは、圧入により接合しようと試みたところ、被膜の一部が削り取られ、磁石本体の一部が露出した状態になった。
【０２０９】
以上のようにして得られた永久磁石とヨークとの接合体を用いて、図４に示すようなロータ（モータ用部品）を得た。なお、ヨーク、ハブ、スリーブの構成材料としては、それぞれ、快削鋼（ＳＵＭ２１）、アルミニウム、真鍮を用い、ヨークとハブとの接合、ハブとスリーブとの接合は、いずれも、前記と同様の熱カシメにより行った。
【０２１０】
各ロータについて、製造に用いたボンド磁石の寸法（室温（２０℃）における自然状態での寸法：外径×内径（先端部付近を除く）×高さ）、ヨークの寸法（室温（２０℃）における自然状態での寸法：外径×内径（先端部付近を除く）×高さ）、およびヨークの加熱状態での内径を表５に示す。
【０２１１】
【表５】

【０２１２】
［ロータの評価およびモータの製造］
上記のようにして製造された各ロータについて、島津製作所社製動釣合試験機（ＶＣ　００３Ｔ形）を用いて回転アンバランス量の測定を実施した。そのときの回転数は３６００ｒｐｍとした。
回転アンバランス量の測定結果を表６に示す。
【０２１３】
【表６】

【０２１４】
表６から、サンプルＮｏ．１〜Ｎｏ．１７によるロータ（いずれも本発明）では、回転アンバランス量が極めて小さいことがわかる。これに対し、サンプルＮｏ．１９、Ｎｏ．２０によるロータ（いずれも比較例）では、回転アンバランス量が大きい。
【０２１５】
次に、サンプルＮｏ．１〜Ｎｏ．２０によるロータを用いて、図５に示すようなモータを製造した。
【０２１６】
このようにして得られた各モータについて、ステータのコイルへの通電操作（通電時間：３０秒間、最大回転数：７２００ｒｐｍ）を繰り返し行った。
【０２１７】
サンプルＮｏ．１〜Ｎｏ．１７によるモータ（いずれも本発明）では、駆動時の振動、騒音が比較的小さいものであったのに対し、サンプルＮｏ．１９、Ｎｏ．２０によるモータ（いずれも比較例）では、駆動時の振動、騒音が大きかった。
【０２１８】
また、サンプルＮｏ．１９、Ｎｏ．２０によるモータ（いずれも比較例）では、上記の通電操作の回数が約３００００回目に達する頃から振動、騒音（異音）がさらに激しいものとなった。
【０２１９】
上記の通電操作を５００００回行った後、各モータを分解した。分解した各モータからロータを取り出し、これらの各ロータについて、ＪＩＳ　Ｋ　５４０１に記載の方法に準拠して、２４時間暴露試験を実施した。
【０２２０】
その結果、サンプルＮｏ．１８、Ｎｏ．１９によるロータ（いずれも比較例）では、永久磁石周辺に、赤錆等による変色がはっきりと認められた。これに対し、サンプルＮｏ．１〜Ｎｏ．１７によるロータ（いずれも本発明）では、永久磁石の周辺には錆等による変色が認められなかった。
【０２２１】
また、被覆層の形成を前記［１］、［３］で示すような方法に変更した以外は、前記と同様に永久磁石を製造し、前記実施例１〜実施例３と同様の評価を行った。その結果、いずれも、前記と同様な結果が得られた。
【０２２２】
【発明の効果】
以上述べたように、本発明によれば、ハードディスクドライブ等の機器に悪影響を与えにくい永久磁石、モータ用部品およびモータを提供することができる。
【０２２３】
特に、磁石本体の内周面側における被覆層の厚さＤｉと、磁石本体の外周面側における被覆層の厚さＤｏとの間で、Ｄｉ＞Ｄｏの関係を満足することにより、永久磁石からの物質の放出を効果的に防止しつつ、軸ぶれによる、モータ駆動時における振動や騒音（異音）の発生等を効果的に防止できる。また、モータ組み立て時等における永久磁石の欠損、破損等の発生を防止することができる。したがって、高回転型のモータ等に、好適に適用することができ、例えば、ハードディスクドライブ等の機器のさらなる高性能化、高密度化に寄与することができる。
【図面の簡単な説明】
【図１】本発明の永久磁石の第１実施形態を示す断面斜視図である。
【図２】本発明の永久磁石の第２実施形態を示す断面斜視図である。
【図３】本発明の永久磁石の他の実施形態を示す断面斜視図である。
【図４】本発明のモータ用部品（ロータ）の好適な実施形態を示す断面側面図である。
【図５】図４に示すモータ用部品を有するモータの好適な実施形態を示す断面側面図である。
【図６】被覆層の形成時に用いる装置の構成の一例を模式的に示す側面図である。
【符号の説明】
１……永久磁石　１１……磁石本体　１２……被覆層　１３……下地層　３……ロータ　３１……ハブ　３２……スリーブ　３２１……軸受け部　３２２……軸受け部　３２３……溝　３３……ヨーク　４……モータ　４１……シャフト　４２……ステータ　４２１……コア　４２２……コイル　４３……基部　４４……フランジ　４５……スラスト受け板　５……ローラ　６……ローラ　７……ローラ　８……遮蔽板[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a permanent magnet, a motor component, and a motor.
[0002]
[Prior art]
Hard disk drives are widely used as computer peripherals. A hard disk drive generally has a motor for rotating a disk.
[0003]
As the permanent magnet constituting the motor, for example, any magnet such as a cast magnet, a sintered magnet, and a bonded magnet may be used. However, in applications where miniaturization and precision are required, such as a hard disk drive, molding is performed. Bond magnets having excellent properties are widely used.
[0004]
Bonded magnets are formed by combining magnet powder with a binder resin, and thus have the characteristic of being excellent in moldability as described above, but particularly at high temperatures, various compounds such as organic compounds, inorganic compounds, and ions. Has the property of being easily released. It is known that the substance released in this way is deposited on a magnetic head, a disk surface, or the like.
[0005]
By the way, in recent years, the performance and density of hard disk drives have been remarkably increasing, and it is considered that such performance and density will be further advanced in the future. As the performance and density of the hard disk drive further increase, the above-described deposition of a substance may adversely affect data reading and writing.
[0006]
[Problems to be solved by the invention]
An object of the present invention is to provide a permanent magnet, a motor component, and a motor, which hardly adversely affect a device on which a motor is mounted, particularly a device such as a hard disk drive.
[0007]
[Means for Solving the Problems]
Such an object is achieved by the present invention described in the following (1) to (23).
[0008]
(1) A permanent magnet having a substantially cylindrical magnet main body and a coating layer provided on the surface side thereof,
The coating layer is mainly composed of polyparaxylylene resin,
When the average thickness of the coating layer on the inner peripheral surface side of the magnet main body is Di [μm] and the average thickness of the coating layer on the outer peripheral surface side of the magnet main body is Do [μm], Di> Do A permanent magnet characterized by satisfying the relationship.
[0009]
(2) The permanent magnet according to the above (1), wherein the average thickness Di of the coating layer on the inner peripheral surface side of the magnet main body is 15 to 35 μm.
[0010]
(3) The permanent magnet according to the above (1) or (2), wherein the average thickness Do of the coating layer on the outer peripheral surface side of the magnet main body is less than 15 μm.
[0011]
(4) The permanent magnet according to any one of (1) to (3), wherein the polyparaxylylene resin contains at least one of polymonochloroparaxylylene and polyparaxylylene.
[0012]
(5) The permanent magnet according to any one of (1) to (4), wherein the coating layer is formed by a chemical vapor deposition method.
[0013]
(6) The permanent magnet according to any one of (1) to (5), further including an underlayer between the magnet main body and the coating layer.
[0014]
(7) The permanent magnet according to (6), wherein the underlayer is mainly made of an organic polymer material.
[0015]
(8) The permanent magnet according to (6) or (7), wherein the underlayer has an average thickness of 10 μm or less.
[0016]
(9) At 70 ° C., the amount of gas generated for 16 hours is 1 m in surface area²The permanent magnet according to any one of the above (1) to (8), wherein the amount is 50 mg or less per unit.
[0017]
(10) Br extracted when immersed in pure water at 80 ° C. for 30 minutes⁻, NO_X ⁻, Cl⁻, PO₄ ^3-, F⁻, SO₄ ^2-, NH₄ ⁺Total amount is 1m surface area²The permanent magnet according to any one of the above (1) to (9), wherein the amount is 150 mg or less per unit.
[0018]
(11) The permanent magnet according to any one of (1) to (10), wherein the porosity of the magnet main body is 7.0 vol% or less.
[0019]
(12) The permanent magnet according to any one of the above (1) to (11), wherein the magnet main body is a bonded magnet formed by bonding magnet powder with a bonding resin.
[0020]
(13) The permanent magnet according to (12), wherein the magnet powder has a composition including a rare earth element, a transition metal, and boron.
[0021]
(14) The permanent magnet according to the above (12) or (13), wherein the content ratio of the magnet powder in the bonded magnet is 93 to 99 wt%.
[0022]
(15) The permanent magnet according to any one of (1) to (14), wherein the magnet body is chamfered.
[0023]
(16) A permanent magnet according to any one of the above (1) to (15),
A motor component comprising: a support member that supports the permanent magnet.
[0024]
(17) The motor component according to (16), wherein the permanent magnet is supported and fixed to an inner peripheral side of the support member.
[0025]
(18) The motor component according to (16) or (17), wherein the permanent magnet is supported and fixed to the inner peripheral side of the support member by press-fitting.
[0026]
(19) The motor part according to any one of the above (16) to (18), wherein the motor part is a rotor.
[0027]
(20) The motor component according to (19), wherein the rotational unbalance amount of the rotor is 0.05 g · cm or less.
[0028]
(21) A motor provided with the motor component according to any one of (16) to (20).
[0029]
(22) The motor according to (21), which is used for a hard disk drive.
[0030]
(23) The motor according to the above (21) or (22), wherein the motor is used in a region where the maximum rotation speed is 3600 rpm or more.
[0031]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of a permanent magnet, a motor component, and a motor according to the present invention will be described with reference to the accompanying drawings.
[0032]
FIG. 1 is a sectional perspective view showing a first embodiment of the permanent magnet of the present invention.
The permanent magnet 1 of the present invention has a magnet main body 11 and a coating layer 12 formed on the surface side of the magnet main body 11.
[0033]
The magnet main body 11 has a substantially cylindrical shape. By having such a shape, for example, it can be suitably used for manufacturing a motor described later.
[0034]
The magnet main body 11 is multi-pole magnetized.
As the magnet main body 11, for example, any magnet such as a cast magnet, a sintered magnet, a bonded magnet, a magnet obtained by a method such as rolling, forging, and hot extrusion may be used. Among them, for example, when the permanent magnet 1 of the present invention is used for a motor as described later, a bonded magnet is advantageous in that a relatively small magnet or a magnet having a small thickness can be easily manufactured.
[0035]
The bonded magnet is mainly composed of magnet powder and a binder resin (binder).
[0036]
As the magnet powder constituting the bonded magnet, for example, a rare earth magnet powder containing a rare earth element and a transition metal as basic components is preferably used.
[0037]
As the rare earth magnet powder (hereinafter, also simply referred to as “magnet powder”), one made of an alloy containing a rare earth element, a transition metal, and boron is preferable.
[0038]
In particular, R (where R is at least one of rare earth elements including Y), a transition metal (TM) mainly composed of Fe, and B as basic components (hereinafter, R-TM- (Referred to as a B-based alloy).
[0039]
Typical R-TM-B alloys include Nd-Fe-B alloys, Pr-Fe-B alloys, Nd-Pr-Fe-B alloys, and Nd-Dy-Fe-B alloys. , Ce-Nd-Fe-B-based alloys, Ce-Pr-Nd-Fe-B-based alloys, and alloys in which part of Fe in these is replaced with another transition metal such as Co or Ni.
[0040]
Examples of the rare earth element include Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and misch metal. More than one species can be included. In addition, examples of the transition metal include Fe, Co, and Ni, and one or more of these may be included.
[0041]
At least two of such R-TM-B alloys may be mixed and used. Thereby, the advantages of the respective magnet powders to be mixed can be obtained, and desired magnetic characteristics can be easily obtained.
[0042]
Further, at least one of the R-TM-B alloys and a ferrite powder (for example, BaO.6Fe₂O₃Ba-ferrite, SrO.6Fe₂O₃And Sr-ferrites, such as those obtained by substituting some of them with other transition metals or rare earth elements, etc.). Thereby, the advantages of the respective magnet powders to be mixed can be obtained, and desired magnetic characteristics can be easily obtained.
[0043]
Further, in order to improve magnetic properties such as coercive force and maximum magnetic energy product, or to improve heat resistance and corrosion resistance, in the magnet material, Al, Cu, Ga, Si, Ti, V, Ta, Zr, Nb, Mo, Hf, Ag, Zn, P, Ge, Cr, W, etc. can also be contained.
Further, the content ratio of the magnet powder in the magnet main body 11 is preferably 93 to 99 wt%, more preferably 94 to 98.5 wt%. If the content of the magnet powder is less than the lower limit, sufficient magnetic properties may not be obtained depending on the use of the permanent magnet 1 or the like. On the other hand, when the content of the magnet powder exceeds the upper limit, the moldability of the magnet main body 11 decreases, and the porosity in the magnet main body 11 tends to rapidly increase. Even so, it may be difficult to sufficiently exert the effects of the present invention.
[0044]
Examples of the binding resin (binder) include a thermoplastic resin and a thermosetting resin.
[0045]
Examples of the thermoplastic resin include polyamide (eg, nylon 6, nylon 46, nylon 66, nylon 610, nylon 612, nylon 11, nylon 12, nylon 6-12, nylon 6-66, 9T nylon), and thermoplastic polyimide. Liquid crystal polymers such as aromatic polyesters, polyphenylene oxide, polyphenylene sulfide, polyethylene, polypropylene, polyolefins such as ethylene-vinyl acetate copolymer, modified polyolefins, polyesters such as polycarbonate, polymethyl methacrylate, polyethylene terephthalate, and polybutylene terephthalate; Ether, polyetheretherketone, polyetherimide, polyacetal, polyacrylic, etc., or copolymers, blends, and polymers based on these Roy and the like, can be used as a mixture of two or more of them.
[0046]
Such a thermoplastic resin has an advantage that, due to its type, copolymerization, and the like, a wide range of selections can be made, for example, those that emphasize moldability and those that emphasize heat resistance and mechanical strength. is there.
[0047]
On the other hand, examples of the thermosetting resin include various epoxy resins such as bisphenol type, novolak type, and naphthalene type, phenol resin, urea resin, melamine resin, polyester (unsaturated polyester) resin, polyimide resin, silicone resin, and polyurethane resin. And the like, and one or more of these can be used as a mixture.
[0048]
The thermosetting resin (uncured) used may be liquid at room temperature or solid (powder).
[0049]
Further, a small amount of additives such as a lubricating material and an antioxidant may be added to the constituent material of the magnet body 11.
[0050]
The method for forming the bonded magnet is not particularly limited, such as press molding, injection molding, and extrusion molding.
[0051]
In the case of press molding, for example, molding pressure: 2 to 16 tons / cm²It is preferable to heat and cure at a firing temperature of 100 to 200 ° C.
[0052]
In the case of injection molding, for example, molding temperature: 200 to 280 ° C, mold closing pressure: 0.1 to 3 ton / cm²It is preferred to mold with.
[0053]
In the case of extrusion molding, for example, molding is preferably performed at a molding temperature of 150 to 250 ° C. and a molding temperature of 2 to 10 mm / sec.
[0054]
The magnet main body 11 formed by the various forming methods in this way is subjected to secondary processing into desired dimensions and shapes as required.
[0055]
Although the magnetic characteristics of the magnet body 11 are not particularly limited, the magnetic energy product (BH)_maxIs 32kJ / m³The above is preferable, and 48 kJ / m³The above is more preferable, and 64 kJ / m³The above are more preferred.
[0056]
Further, the porosity of the magnet main body 11 is preferably 7.0 vol% or less, and more preferably 5.0 vol% or less. If the porosity exceeds the upper limit, the effect of the present invention may not be sufficiently exerted even if a coating layer 12 described later is formed.
[0057]
Further, the magnet main body 11 may be one in which a corner at an end thereof (at least a corner on the outer peripheral side of the front end) is chamfered. Thereby, the permanent magnet 1 is less likely to cause defects such as chipping. Further, for example, when the permanent magnet 1 of the present invention is used for a motor, when the permanent magnet 1 and the yoke (support member) are joined by press-fitting, the operation can be easily performed. Further, when the press-fitting operation is performed, it is possible to more effectively prevent the surface of the permanent magnet 1 from being damaged. As a result, corrosion of the permanent magnet 1 and reduction in mechanical strength are prevented, and as a result, the long-term stability of the motor is improved.
[0058]
The permanent magnet 1 of the present invention has a coating layer 12 on the surface side of a magnet main body 11. By having the coating layer 12, the magnet main body 11 is in a state of being shielded from the outside.
[0059]
The coating layer 12 is mainly made of polyparaxylylene resin. Polyparaxylylene resin has excellent gas barrier properties. For this reason, even when the permanent magnet 1 is used in a high-temperature environment or the like, release of substances such as organic compounds, inorganic compounds, and ions from the magnet main body 11 and the like to the outside of the permanent magnet 1 (hereinafter simply referred to as “ Release of a substance ") can be effectively prevented. In addition, the polyparaxylylene resin hardly emits a substance such as outgas from itself. Therefore, even when the permanent magnet 1 on which the coating layer 12 is formed is used for a device such as a motor for a hard disk drive, which will be described later, the permanent magnet 1 is hardly affected.
[0060]
In addition, polyparaxylylene resin has appropriate flexibility.
Thereby, the following effects can be obtained while sufficiently maintaining the dimensional accuracy of the permanent magnet 1.
That is, for example, when the permanent magnet 1 is used for manufacturing a motor and the permanent magnet 1 and the yoke (support member) are joined by heat caulking or press-fitting, the permanent magnet is damaged or damaged at the time of assembling the motor or the like. , And the joining strength between the permanent magnet 1 and the yoke in the assembled motor can be made particularly excellent.
[0061]
In addition, polyparaxylylene resin has appropriate lubricity and is excellent in scratch resistance.
Thus, for example, when the permanent magnet 1 is used for a motor, when the permanent magnet 1 and the yoke (support member) are joined by press-fitting, the operation can be easily performed. In addition, it is possible to effectively prevent the surface of the permanent magnet 1 from being damaged at the time of press-fitting. As a result, it is possible to sufficiently prevent the substance from being released from the permanent magnet 1 and to prevent corrosion of the permanent magnet 1 and decrease in mechanical strength. Therefore, the reliability of the motor using the permanent magnet 1 is improved. The dynamic friction coefficient of such a polyparaxylylene resin (measured according to ASTM-D1894) is generally about 0.1 to 0.5.
[0062]
Further, the film composed of polyparaxylylene resin has excellent strength. Thereby, the mechanical strength of the permanent magnet 1 as a whole is improved, so that the permanent magnet 1 is used in a state where a relatively large external force is applied or in a state where the external force is continuously applied (particularly, a motor described later). Can be suitably applied.
[0063]
Further, as described above, polyparaxylylene resin has excellent gas barrier properties. Therefore, the provision of the coating layer 12 can effectively prevent the magnet body 11 from being oxidized and the like, and the corrosion resistance and the long-term stability of the permanent magnet 1 are improved.
[0064]
Now, as described above, polyparaxylylene resin has excellent gas barrier properties. Such a gas barrier effect is more remarkably exhibited as the thickness of the coating layer 12 is larger. That is, if the thickness of the coating layer 12 is too small, the effect of the gas barrier property cannot be sufficiently obtained.
[0065]
In general, when a permanent magnet is used in a motor or the like to be described later (see FIG. 5), the emission of the substance from the permanent magnet as described above mainly occurs from the inner peripheral surface side of the permanent magnet. That is, since the outer peripheral surface of the permanent magnet is bonded to the yoke 33, the above-mentioned substance hardly emits or hardly emits the substance as described above.
[0066]
Therefore, on the outer peripheral side of the permanent magnet 1, the thickness of the coating layer 12 may not be so large. On the contrary, if the thickness of the coating layer 12 on the outer peripheral side of the permanent magnet 1 is too large, the gap between the permanent magnet 1 and the yoke 33 becomes large. 12 has a large variation in film thickness. Accordingly, the amount of unbalance of the center of gravity of the rotor 3 increases, and vibration and noise (abnormal noise) due to shaft runout are likely to occur. As a result, it becomes difficult to apply the permanent magnet 1 to a motor used in a high rotation region as described later.
[0067]
As described above, according to the present invention, the thickness of the coating layer is reduced (or not formed) on the outer peripheral side joined to the yoke, and the thickness of the coating layer is reduced on the inner peripheral side where emission of volatile substances is a problem. By increasing the thickness, the effect of preventing the emission of the substance from the permanent magnet and the effect of reducing the amount of unbalance when applied to the rotor are compatible.
That is, in the present invention, when the average thickness on the inner peripheral surface side of the magnet main body 11 is Di [μm] and the average thickness on the outer peripheral surface side of the magnet main body 11 is Do [μm], the relationship of Di> Do is satisfied. To be satisfied.
[0068]
In the drawings, the difference between the thickness on the inner peripheral surface side of the coating layer 12 and the thickness on the outer peripheral surface side is exaggerated.
[0069]
As described above, the present invention is characterized in that it satisfies the relationship of Di> Do, but preferably satisfies the relationship of 0 <Do / Di <0.99, and 0.05 <Do / Di <. More preferably, the relationship of 0.76 is satisfied, and even more preferably, the relationship of 0.05 <Do / Di <0.5 is satisfied. By satisfying such a relationship, the above-described effects become more remarkable.
[0070]
The average thickness Di of the coating layer 12 on the inner peripheral surface side of the magnet main body 11 is not particularly limited, but is preferably 15 to 35 μm, and more preferably 16 to 30 μm. When the value of Di is less than the lower limit, the effect of the gas barrier properties of the coating layer 12 is reduced, and defects such as pinholes are liable to occur depending on the porosity of the magnet main body 11 and the like. For this reason, depending on the usage environment of the permanent magnet 1, it may be difficult to sufficiently prevent the substance from being released from the permanent magnet 1. On the other hand, when Di exceeds the upper limit, the dimensional tolerance of the permanent magnet 1 as a whole tends to increase.
[0071]
The average thickness Do of the coating layer 12 on the outer peripheral surface side of the magnet main body 11 is not particularly limited, but is preferably less than 15 μm, and more preferably 1.5 to 13.0 μm. When Do exceeds the upper limit, the dimensional tolerance of the permanent magnet 1 as a whole tends to increase.
[0072]
Further, since the coating layer 12 having a predetermined thickness is provided on the outer peripheral side of the permanent magnet, when the permanent magnet 1 and the yoke (support member) are joined by press-fitting, the press-fitting operation can be easily performed. It becomes possible. Further, since the coating layer 12 having a predetermined thickness is provided on the outer peripheral side of the permanent magnet, when the permanent magnet 1 and the yoke (supporting member) are joined by heat caulking or press-fitting, the assembling of the motor is performed. In this case, the joint strength between the permanent magnet 1 and the yoke in the assembled motor can be made particularly excellent while sufficiently preventing the permanent magnet from being damaged or damaged.
[0073]
Examples of the polyparaxylylene resin constituting the coating layer 12 include polyparaxylylene (poly-para-xylylene), polymonochloroparaxylylene (poly-monochloro-para-xylylene), and polydichloroparaxylylene (poly-dichloro). -Para-xylylene), polymonofluoroparaxylylene (poly-monofluoro-para-xylylene), polymonoethylparaxylylene (poly-monoethyl-para-xylylene) and the like. Preferably, it contains at least one of len and polymonochloroparaxylylene.
Among them, polyparaxylylene is particularly excellent in adhesion to the magnet main body 11.
In addition, polyparaxylylene has particularly excellent flexibility. For this reason, when the permanent magnet 1 is used for manufacturing a motor to be described later and is supported and fixed to the support member by press-fitting and heat caulking, the joining strength between the permanent magnet 1 and the support member is particularly excellent. .
Further, polymonochloroparaxylylene has particularly excellent gas barrier properties. Thereby, the release of the substance from the permanent magnet 1 can be more effectively prevented.
[0074]
Such a coating layer 12 is usually formed by using a dimer corresponding to paraxylylene resin as a raw material and performing a CVD (chemical vapor deposition) method. By using the CVD method to form the coating layer 12, the coating layer 12 that is denser and has excellent adhesion to the magnet main body 11 can be formed stably. In addition, by using the CVD method for forming the coating layer 12, variations in the thickness of the coating layer 12 on the outer peripheral surface side of the magnet main body 11 and variations in the thickness of the coating layer 12 on the inner peripheral surface side of the magnet main body 11 are reduced. The coating layer 12 can be easily formed so as to satisfy the relationship of Di> Do while sufficiently suppressing the relationship.
[0075]
When the coating layer 12 is formed by the above-described CVD method, for example, the magnet body 11 may be rotated.
[0076]
Incidentally, in the permanent magnet 1 of the present invention, the average thickness Di of the coating layer 12 on the inner peripheral surface side of the magnet main body 11 and the average thickness Do of the coating layer 12 on the outer peripheral surface side of the magnet main body 11 are as described above. It is characterized by satisfying such a relationship. The conditions for forming the coating layer 12 are not particularly limited as long as such a relationship is satisfied. For example, by forming the coating layer 12 by a method such as the following [1] to [3], The coating layer 12 satisfying the above-described relationship can be easily and reliably formed.
[0077]
[1] For example, a polyparaxylylene resin (coating layer 12) is formed in a state where the outer peripheral surface side of the magnet main body 11 is masked. Thereby, the formation of the coating layer 12 is inhibited on the outer peripheral surface side of the masked magnet main body 11, so that the coating layer 12 satisfies the above-described relationship.
In such a method, for example, a heat-resistant tape, a metal ring, or the like can be used as the masking.
Further, the above-described masking may be used in the entire process of forming the coating layer 12 or may be used in a part of the process of forming the coating layer 12. For example, after covering the entire surface of the magnet main body 11 with a relatively small-thickness polyparaxylylene resin, the outer peripheral surface side is masked, and in this state, the polyparaxylylene resin is again coated. The coating layer 12 satisfying the above-described relationship may be formed. Further, the coating layer 12 may be formed by repeatedly performing the coating of the polyparaxylylene resin without masking and the coating of the polyparaxylylene resin with masking. This makes it possible to control Di and Do more accurately.
[0078]
[2] Also, for example, by coating the polyparaxylylene resin while rotating the magnet main body 11 on the rollers 5, 6, and 7 as shown in FIG. 6, the above relation is satisfied. The coating layer 12 can be formed. That is, in such a method, since the outer peripheral surface side of the magnet main body 11 is in contact with the surfaces of the rollers 5 and 6 when the coating layer 12 is formed, the outer peripheral surface side of the magnet main body 11 has an inner peripheral surface side. , The film forming speed of the coating layer 12 is reduced. As a result, the formed coating layer 12 satisfies the above relationship. Further, the number of rollers to be brought into contact with the magnet main body 11, the size of the rollers, and the like may be appropriately selected. This makes it possible to control Di and Do more accurately. When the covering layer 12 is formed by such a method, for example, a shielding plate 8 as shown in FIG. 6 may be provided. Thereby, the film forming speed of the coating layer 12 on the outer peripheral surface side of the magnet main body 11 can be further reduced with respect to the film forming speed of the coating layer 12 on the outer peripheral surface side of the magnet main body 11.
[0079]
[3] Also, in a coating layer forming apparatus (for example, a vapor deposition apparatus), the polyparaxylylene resin is coated while the magnet main body 11 is rotated using a tumble or barrel tank, whereby The coating layer 12 satisfying the above relationship can be formed. When using such a method, the rotation speed of the tumble or barrel tank is preferably 10 rpm or less. This makes it possible to more accurately control Di and Do so as to satisfy the above-described relationship.
[0080]
Prior to the formation of the coating layer 12, the surface of the magnet body 11 may be subjected to a pretreatment. Examples of the pretreatment include blasting, alkali cleaning (alkali degreasing), acid cleaning, water cleaning (including pure water cleaning), organic solvent cleaning, ultrasonic cleaning, cleaning treatment such as bombardment, etching, and the like. Can be By performing such a pretreatment, the coating layer 12 can be formed more uniformly and densely and stably.
[0081]
In addition, the composition in each part of the coating layer 12 may or may not be constant. For example, the coating layer 12 may be a material (gradient material) whose composition changes sequentially along the thickness direction. Further, the permanent magnet 1 may have two or more coating layers 12 as described above.
[0082]
As described above, the permanent magnet 1 is characterized in that the amount of released substances is extremely small.
[0083]
Specifically, the amount of gas generated in the permanent magnet 1 at 70 ° C. for 16 hours is such that the surface area of the permanent magnet 1 is 1 m²It is preferably 50 mg or less, more preferably 30 mg or less, and even more preferably 20 mg or less. By satisfying such conditions, the permanent magnet 1 is unlikely to adversely affect devices such as a hard disk drive.
[0084]
When the permanent magnet 1 is immersed in pure water at 80 ° C. for 30 minutes, Br is extracted.⁻, NO_X ⁻, Cl⁻, PO₄ ^3-, F⁻, SO₄ ^2-, NH₄ ⁺Is the total surface area of the permanent magnet 1²Per unit weight is preferably 150 mg or less, more preferably 100 mg or less, and even more preferably 50 mg or less. By satisfying such conditions, the permanent magnet 1 is unlikely to adversely affect devices such as a hard disk drive.
[0085]
Next, a second embodiment of the permanent magnet of the present invention will be described. Hereinafter, the permanent magnet of the present embodiment will be described focusing on differences from the above-described embodiment, and the description of the same items will be omitted.
[0086]
FIG. 2 is a sectional perspective view showing a second embodiment of the permanent magnet of the present invention.
As shown in FIG. 2, the permanent magnet 1 of the present embodiment has a base layer 13 between a magnet main body 11 and a coating layer 12. Thus, the coating layer 12 does not need to be formed directly on the surface of the magnet main body 11.
[0087]
By having the underlayer 13 in this manner, the adhesion between the magnet main body 11 and the coating layer 12 is improved, and the occurrence of defects such as peeling of the coating layer 12 can be effectively prevented. As a result, the reliability of the permanent magnet 1 is particularly excellent.
[0088]
As a constituent material of the underlayer 13, for example, Cu, Al, Pd, Au, Ag, Pb, Sn, Ni, Fe, Co, In, V, Cr, Be, Zn, Ti, Mn, Cd, Pt, Rh And inorganic materials containing one or more selected from the group consisting of: and organic polymer materials such as epoxy resins, acrylic resins, phenolic resins, and polyester resins. Among them, the underlayer 13 is preferably mainly composed of an organic polymer material, and is composed of a material containing at least one of an epoxy resin, a phenol resin, and an acrylic resin. Is more preferred. When the underlayer 13 is made of such a material, the above-described effects become more remarkable.
[0089]
The average thickness of the underlayer 13 is not particularly limited, but is preferably 10.0 μm or less, and more preferably 1.0 to 8.0 μm. If the average thickness of the underlayer 13 is less than the lower limit, the effect of the underlayer 13 may not be sufficiently obtained. On the other hand, when the average thickness of the underlayer 13 exceeds the upper limit, the function of the coating layer 12 to improve the gas barrier properties and the surface cleanliness tends to decrease.
[0090]
The method for forming the underlayer 13 is not particularly limited, and examples thereof include dipping, doctor blade, spin coating, brush coating, spray coating, various coating methods such as a roll coater, thermal spraying, electrolytic plating, immersion plating, and electroless plating. , Vacuum deposition, sputtering, thermal CVD, plasma CVD, chemical vapor deposition (CVD) such as laser CVD, dry plating such as ion plating, and the like.
[0091]
Prior to the formation of the underlayer 13, the surface of the magnet body 11 may be subjected to a pretreatment. Examples of the pretreatment include blasting, alkali cleaning (alkali degreasing), acid cleaning, water cleaning (including pure water cleaning), organic solvent cleaning, ultrasonic cleaning, cleaning treatment such as bombardment, etching, and the like. Can be By performing such a pretreatment, for example, the adhesion between the magnet main body 11 and the underlayer 13 is improved, and as a result, the adhesion between the magnet main body 11 and the coating layer 12 is further improved. it can.
[0092]
The permanent magnet 1 can be obtained by forming the coating layer 12 on the surface of the underlayer 13 in the same manner as in the above embodiment.
[0093]
Prior to the formation of the covering layer 12, the surface of the underlayer 13 may be subjected to a pretreatment. Examples of the pretreatment include blasting, alkali cleaning (alkali degreasing), acid cleaning, water cleaning (including pure water cleaning), organic solvent cleaning, ultrasonic cleaning, cleaning treatment such as bombardment, etching, and the like. Can be By performing such a pretreatment, for example, the adhesion between the underlayer 13 and the coating layer 12 is improved, and as a result, the adhesion between the magnet main body 11 and the coating layer 12 can be further improved. .
[0094]
In the configuration shown in FIG. 2, the base layer 13 is formed on the entire surface of the magnet body 11, but may be formed on at least a part of the surface of the magnet body 11. For example, the underlayer 13 may be formed only on the inner peripheral surface side of the magnet main body 11 as shown in FIG. 3, or may be formed only on the portion excluding the outer peripheral surface side of the magnet main body 11. It may be. In such a case, the ratio between the deposition rate of the coating layer 12 on the inner peripheral surface side of the magnet main body 11 and the deposition rate of the coating layer 12 on the outer peripheral surface side of the magnet main body 11 is, for example, the base layer 13. It can be adjusted by selecting the constituent material, film thickness, and the like.
[0095]
Next, preferred embodiments of a motor component and a motor according to the present invention including the above-described permanent magnet will be described.
[0096]
FIG. 4 is a sectional side view showing a preferred embodiment of a motor component (rotor) of the present invention, and FIG. 5 is a sectional side view showing a preferred embodiment of a motor having the motor component shown in FIG. . 4 and 5, the configuration having the permanent magnet 1 as shown in FIG. 1 has been described. However, it is needless to say that the permanent magnet 1 may have a configuration as shown in FIGS. No. Hereinafter, in FIG. 4, the lower side is referred to as “base end” and the upper side is referred to as “distal end”.
[0097]
First, a preferred embodiment of a motor component (rotor) of the present invention will be described. As shown in FIG. 4, the rotor (rotor) 3 includes a hub 31, a sleeve 32 joined to an inner surface on the distal end side of the hub 31, and a yoke 33 joined to an inner surface on the proximal end side of the hub 31. And the permanent magnet 1 joined and fixed to the inner peripheral surface side of the yoke 33 (support member).
[0098]
The sleeve 32 has a substantially cylindrical shape, and has a groove (intermediate relief portion) 323 on the inner peripheral surface side.
[0099]
The sleeve 32 functions as a bearing (dynamic fluid bearing) when used for manufacturing the motor 4 as described below. That is, the sleeve 32 has bearing portions 321 and 322 protruding inward at two different locations in the longitudinal direction (vertical direction in FIG. 1). When the bearing is such a dynamic pressure fluid bearing (sliding bearing), it can be suitably applied to a motor used in a high rotation region as described later.
[0100]
As a constituent material of the sleeve 32, for example, a copper alloy such as copper or brass, an iron alloy such as aluminum, iron or stainless steel, or a metal sintered body using them as a powder material, Al₂O₃(Alumina), titania (TiO₂), Zirconia (ZrO)₂) Etc. as a main component, and synthetic resins.
[0101]
The yoke 33 has a substantially cylindrical shape, and is joined and fixed to the inner surface on the base end side of the hub 31.
[0102]
The material of the yoke 33 is not particularly limited, but is usually made of a metal or alloy material. Examples of the material constituting the yoke 33 include Fe, Al, free-cutting steel, stainless steel, brass, a sintered alloy, and an alloy containing at least one of these materials. It is preferably made of a material mainly containing Fe or Al. Thereby, the yoke 33 has sufficient mechanical strength, and the joining strength (adhesion) with the coating layer 12 of the permanent magnet 1 is particularly excellent.
[0103]
The constituent material of the yoke 33 has a coefficient of thermal expansion (linear expansion coefficient) around room temperature of 4 to 30 [× 10^-6K^-1And preferably 8 to 25 [× 10^-6K^-1] Is more preferable. When the thermal expansion coefficient (linear expansion coefficient) of the constituent material of the yoke 33 is less than the lower limit, for example, when the permanent magnet 1 and the yoke 33 are joined by thermal caulking, the yokes 33 are compared in the manufacturing process. Otherwise, it may be difficult to insert the permanent magnet 1 into the hollow portion of the yoke 33. On the other hand, when the coefficient of thermal expansion (linear expansion coefficient) of the constituent material of the yoke 33 exceeds the upper limit, when the rotor 3 is exposed to a high-temperature environment, the adhesion between the permanent magnet 1 and the yoke 33 decreases. there is a possibility.
[0104]
Further, the yoke 33 preferably has a surface roughness Ra of 0.5 to 10.0 μm, more preferably 1.0 to 5.0 μm. When the surface roughness Ra of the yoke 33 is within the above range, for example, when the permanent magnet 1 and the yoke 33 are joined by press fitting, the operation can be easily performed. Further, it is possible to more effectively prevent the surface of the permanent magnet 1 from being damaged during press-fitting. As a result, in the assembled rotor 3, it is possible to sufficiently prevent the substance from being released from the permanent magnet 1 while preventing corrosion of the permanent magnet 1, reduction in mechanical strength, and the like. Therefore, the reliability of the rotor (motor component) 3 is improved.
[0105]
On the other hand, if the surface roughness Ra of the yoke 33 is less than the lower limit, the adhesion (bonding strength) between the permanent magnet 1 and the yoke 33 may be reduced. If the surface roughness Ra of the yoke 33 exceeds the upper limit, the above effects may not be sufficiently obtained.
[0106]
As described above, the permanent magnet 1 includes the cylindrical magnet body 11 and the coating layer 12 formed on the surface of the magnet body 11.
The magnet main body 11 is multi-pole magnetized.
[0107]
Since the permanent magnet 1 has the coating layer 12 as described above, the release of the substance from the permanent magnet 1 is prevented, and the corrosion of the permanent magnet 1 and a decrease in mechanical strength are also prevented. Therefore, the rotor 3 can stably exhibit the characteristics of the magnet main body 11 over a long period of time, and the reliability of the motor having the rotor 3 is also improved.
[0108]
Such a permanent magnet 1 is fixed to the yoke 33 (support member) by heat caulking or press fitting. Thus, the permanent magnet 1 is supported and fixed to the yoke 33 with sufficient adhesion (joining strength). As described above, when the permanent magnet 1 and the yoke 33 are joined with sufficiently high strength, the rotor 3 can be connected to a motor (particularly, a motor used in a high rotation region, a motor used repeatedly, In the case where the present invention is applied to a motor that is used continuously, the occurrence of poor connection between the permanent magnet 1 and the yoke 33 is more effectively prevented. As a result, problems such as generation of abnormal noise when the motor is driven and deterioration of the torque characteristics of the motor are more effectively prevented. In addition, by effectively preventing the above-described joint failure, the motor 4 having the yoke 33 is less likely to cause a failure, breakage, and the like, and has excellent reliability.
[0109]
Further, since the permanent magnet 1 and the yoke 33 are joined by heat caulking or press-fitting, the joint between the permanent magnet 1 and the yoke 33 does not need to use an organic adhesive as conventionally used. High bonding strength can be obtained. As described above, when the permanent magnet 1 and the yoke 33 are joined without using the organic adhesive, the unbalance amount (rotational unbalance amount) of the center of gravity of the rotor 3 can be reduced. In particular, in the permanent magnet 1, the average thickness Di of the coating layer 12 on the inner peripheral surface side of the magnet main body 11 and the average thickness Do of the coating layer 12 on the outer peripheral surface side of the magnet main body 11 have the above-described relationship. Is satisfied, the emission of the substance from the permanent magnet 1 can be sufficiently effectively prevented, and the dimensional tolerance of the entire permanent magnet 1 can be made sufficiently small. As a result, the center of gravity of the rotor 3 can be reduced. The unbalance amount (rotational unbalance amount) can be made sufficiently small. Therefore, even when the motor 4 to which the rotor 3 is applied is used in, for example, a high rotation region, vibration and noise (abnormal noise) due to shaft runout hardly occur.
[0110]
The measurement of the unbalance amount of the rotor 3 as described above can be generally regarded as periodic stress generation in the radial direction accompanying the rotation of the rotor 3. By converting this stress electrically, it can be measured as an unbalance amount. This rotational unbalance amount is preferably 0.05 g · cm or less, more preferably 0.04 g · cm or less, and even more preferably 0.02 g · cm or less.
[0111]
When the rotational unbalance amount of the rotor 3 is 0.05 g · cm or less, even when applied to a motor used in a high rotational speed region, vibration due to shaft deviation and noise (abnormal noise) hardly occur. . Further, the yield of the motor assembling process is greatly improved, and the productivity can be significantly improved.
[0112]
The rotor (motor component) 3 as described above is obtained by supporting and fixing the permanent magnet 1 to the yoke (support member) 33 by heat caulking or press fitting.
[0113]
In order to fix the permanent magnet 1 to the yoke 33 by thermal caulking, the thermal caulking inserts the permanent magnet 1 into the hollow portion of the yoke 33 at a higher temperature than the permanent magnet 1, and then cools the yoke 33. It is done by doing. The thermal caulking may be performed, for example, by inserting the cooled permanent magnet 1 into the hollow portion of the yoke 33 at a higher temperature than the permanent magnet 1 and then increasing the temperature of the permanent magnet 1.
[0114]
When the permanent magnet 1 is supported and fixed to the yoke 33 by press-fitting, the relative moving speed (approaching speed) between the permanent magnet 1 and the yoke 33 in the axial direction (vertical direction in the drawing) is 0. It is preferably 2 to 20 cm / sec, more preferably 0.5 to 10 cm / sec.
[0115]
When the relative moving speed between the permanent magnet 1 and the yoke 33 is within the above range, the permanent magnet 1 can be efficiently pressed in while effectively preventing the surface of the permanent magnet 1 from being damaged. Can be. Thus, by preventing the surface of the permanent magnet 1 from being damaged, it is possible to prevent corrosion of the permanent magnet 1, reduction in mechanical strength, and the like. Therefore, the reliability of the rotor (motor component) 3 is improved, and the long-term stability of the motor is also improved.
[0116]
When the permanent magnet 1 and the yoke 33 are joined by press-fitting, the corners of the permanent magnet 1 (magnet body 11) (at least the outer peripheral corner of the tip) are chamfered. Is preferred. Thus, the press-fitting operation can be performed more easily. Further, when the press-fitting operation is performed, it is possible to more effectively prevent the surface of the permanent magnet 1 from being damaged. As a result, corrosion of the permanent magnet 1, reduction in mechanical strength, and the like can be prevented. Therefore, the reliability of the rotor (motor component) 3 is improved, and the long-term stability of the motor is also improved.
[0117]
The outer diameter of the permanent magnet 1 joined by heat caulking and press fitting as described above in the natural state (the state before joining with the yoke 33) is the natural state of the corresponding portion of the yoke 33 (joining with the permanent magnet 1). Larger than the inner diameter before Thereby, the joining strength between the permanent magnet 1 and the yoke 33 in the obtained rotor 3 becomes sufficiently large.
[0118]
The joining method of the permanent magnet 1 and the yoke 33 has been described above, but such a joining method can be applied to, for example, the joining of the yoke 33 and the hub 31 and the joining of the hub 31 and the sleeve 32. . As a result, even when applied to a motor used in a high rotation region, the rotor 3 hardly generates vibration due to shaft shake and noise (abnormal noise), and has particularly stable characteristics.
[0119]
Next, a preferred embodiment of the motor of the present invention including the above-described motor component (rotor) will be described.
[0120]
As shown in FIG. 5, the motor (hard disk drive motor) 4 includes the above-described rotor (rotor) 3, a shaft (shaft) 41, a stator (stator) 42, and a base (frame) 43. are doing.
[0121]
The shaft 41 rotatably supports the rotor 3.
The shaft 41 is usually made of a metal material such as stainless steel. Examples of stainless steel include Fe-Cr-Ni alloys such as SUS304, SUS303, SUS316, SUS316L, SUS316J1, and SUS316J1L, and Fe-Cr-based alloys such as SUS405, SUS420J2, SUS430, SUS434, SUS444, SUS429, and SUS430F. No.
[0122]
The stator 42 is arranged so as to face the outer peripheral surface of the permanent magnet 1 with a predetermined gap (gap) therebetween.
The stator 42 includes a core 421 formed of a laminated body of silicon steel sheets punched into a desired shape, and a coil (three-phase coil) 422 formed by winding the core 421.
[0123]
The base portion 43 has a shape having a hollow portion, and the shaft 41 is firmly fixed to the inner peripheral surface side by a method such as press fitting. A stator 42 is supported and fixed to the outer surface of the base 43.
[0124]
Further, a thrust receiving plate 45 is fixed to the distal end side of the sleeve 32 together with the flange 44, and the thrust receiving plate 45 is in contact with the distal end portion of the shaft 41.
[0125]
In such a motor 4, by energizing the coil 422 of the stator 42 through a not-shown conductor, the core 421 is excited and a torque is generated in the rotor 3. In this case, energization of the coil 422 is preferably controlled by motor drive control means (neither is shown) provided with an inverter based on a detection signal from a rotor position sensor for detecting the position of the rotor 3.
[0126]
As described above, in the motor 4, the permanent magnet 1 and the yoke 33 (support member) are joined by heat caulking or press-fitting. Insufficient bonding with the 33 is unlikely to occur. As a result, problems such as generation of abnormal noise when the motor is driven and deterioration of the torque characteristics of the motor are more effectively prevented. In addition, by effectively preventing the above-described joint failure, the motor 4 having the yoke 33 is less likely to cause a failure, breakage, and the like, and has excellent reliability.
[0127]
Further, since the permanent magnet 1 has a configuration in which the coating layer 12 that satisfies the above-described relationship is formed on the surface side of the magnet main body 11, the release of volatile substances from the permanent magnet 1 is sufficiently effective. As a whole, even when the motor 4 is used in a high rotation region, vibration and noise (abnormal noise) due to shaft shake can be made less likely to occur. Therefore, the reliability of the motor 4 is improved.
[0128]
Further, in the motor 4, the permanent magnet 1 and the yoke 33 are joined by heat caulking or press-fitting, so that a conventionally used organic adhesive is applied to the joint between the permanent magnet 1 and the yoke 33. Sufficient bonding strength can be obtained without using it. Thus, when the permanent magnet 1 and the yoke 33 are joined without using the organic adhesive, the unbalance amount (rotational unbalance amount) of the center of gravity of the rotor 3 can be made particularly small. As a result, even when the motor 4 to which the rotor 3 is applied is used in, for example, a high rotation region, vibration or noise (abnormal noise) due to shaft shake is unlikely to occur.
[0129]
By the way, in the conventional manufacturing method using the above-mentioned organic adhesive, there is a case where the excess organic adhesive protrudes to the end face of the rotor from between the permanent magnet and the yoke. Such excess organic adhesive is usually designed with a motor structure that allows the excess adhesive to be dimensionally acceptable. However, the excess adhesive on the end face is affected by centrifugal force, vibration, and torque fluctuation due to rotation of the rotor. Is peeled off, broken, or dropped because of the direct acceleration in the circumferential direction. Some of the adhesive thus dropped may remain in the motor and adversely affect the motor.
[0130]
On the other hand, since the permanent magnet 1 and the yoke 33 are joined by heat caulking or press-fitting, sufficient joining strength can be obtained without using an organic adhesive, so that such a problem can be avoided. Therefore, the permanent magnet 1 of the present invention can be particularly suitably applied to a motor that requires removal of extremely fine foreign matter, such as a motor for a hard disk drive.
[0131]
The motor 4 is preferably used in a region where the maximum rotation speed is 3600 rpm or more, more preferably used in a region of 5000 rpm or more, and more preferably used in a region of 7000 rpm or more. preferable. Since the permanent magnet 1 of the present invention is particularly excellent in mechanical strength and particularly has sufficient rust resistance, if the motor 4 is a motor having such a maximum rotation speed, the effect of the present invention is It will be more prominent.
[0132]
In the case where the joining strength between the permanent magnet and the supporting member is small as in the related art, the permanent magnet 1 of the present invention can be applied to a high-rotation type motor that has been difficult to realize due to problems such as reliability. Can be suitably used.
[0133]
Further, in the case of a high rotation type motor, it is required to further reduce the unbalance amount of the center of gravity of the rotor in order to prevent and suppress the generation of vibrations and noise (abnormal noise) due to shaft shake. By joining the member 33 by heat caulking or press-fitting, it is not necessary to use an organic adhesive, so that it is possible to easily reduce the unbalance amount of the center of gravity of the rotor.
[0134]
In the illustrated configuration, the motor 4 is a motor used for a hard disk drive (hard disk drive motor). In general, a hard disk drive motor is used in a high rotation speed region and has a very high magnetic recording density. Therefore, vibration reduction is one of the most important issues. However, the permanent magnet 1 and the yoke 33 are thermally caulked or fixed. By joining by press fitting, such a problem can be easily avoided.
[0135]
As described above, the permanent magnet, the motor component, and the motor according to the present invention have been described based on the illustrated embodiments, but the present invention is not limited thereto.
[0136]
For example, in the above-described embodiment, the configuration in which the coating layer is formed by the CVD method has been described, but the coating layer may be formed by any method.
[0137]
Further, in the above-described embodiment, the configuration in which the coating layer is formed on the entire surface of the permanent magnet has been described. However, the coating layer may be formed at least on the outer peripheral surface side of the magnet main body. May not be formed on the inner peripheral surface side of.
[0138]
Further, the permanent magnet of the present invention is not limited to those applied to the motor and motor parts as described above.
[0139]
Further, the motor of the present invention is not limited to the outer rotor type as described above, and may be, for example, an inner rotor type, a disk type, or the like.
[0140]
The motor of the present invention is not limited to a hard disk drive motor, and may be of any type.
[0141]
Further, in the above-described embodiment, the configuration in which the support member is a yoke is described. However, the support member is not limited to this, and may be, for example, a shaft (shaft), a hub, a casing, or the like.
[0142]
Further, in the above-described embodiment, the structure having the dynamic pressure fluid bearing structure has been described, but the bearing structure may be any structure. For example, a hydrostatic bearing such as a self-lubricating bearing, an orifice bearing, a pocket bearing, or the like may be used. In addition to the above-described sliding bearing, for example, a rolling bearing (ball bearing), a magnetic bearing, or the like may be used.
[0143]
【Example】
Next, specific examples of the present invention will be described.
[0144]
In the following examples, specific substance names, numerical values, and the like are described, but the present invention is not limited to these examples.
[0145]
(Example 1)
[Manufacture of permanent magnets]
As described below, 20 types of permanent magnets (sample Nos. 1 to 20) having the shape and configuration shown in FIG. 1 were manufactured.
[0146]
<Sample No. 1>
First, Nd-Fe-Co-B-based ultra-quenched magnet powder (using a raw material powder having a particle size of 150 # or less) and a bis-A type epoxy resin as a binding resin are mixed, and these are mixed at room temperature for 35 minutes. The mixture was kneaded to prepare a bonded magnet composition (compound). The mixing ratio (weight ratio) of the magnet powder and the bis-A type epoxy resin was 97.9% by weight and 2.1% by weight, respectively.
[0147]
Next, this compound was weighed and filled into a mold of a press device, and was subjected to about 100 kg / mm at room temperature in a magnetic field-free state.²After compression molding at a pressure of 185 ° C., the epoxy resin was heated and cured at 185 ° C. for 16 minutes to obtain a cylindrical bonded magnet. This bonded magnet was polished in the height direction.
[0148]
Thereafter, the bonded magnet was polished (chamfered) by barrel polishing until each ridge became 0.2R, and this was used as a magnet main body. The obtained magnet main body had a cylindrical shape (room temperature (20 ° C.), natural state) having an outer diameter of 28.4 mm × an inner diameter of 26.2 mm × a height of 4.6 mm. The porosity of the magnet body was 4.1 vol%.
[0149]
Next, the obtained magnet main body was washed. As cleaning of the magnet body, pure water ultrasonic cleaning was performed for 3 minutes. Then, it dried at 85 degreeC for 40 minutes.
[0150]
A coating layer made of polyparaxylylene was formed on the surface of the cleaned magnet body in this manner.
[0151]
The coating layer was formed by the following CVD (chemical vapor deposition) method.
First, di-para-xylylene (a dimer corresponding to polyparaxylylene) as a raw material was vaporized at a temperature of 150 to 175 ° C and a pressure of 100 to 135 Pa.
[0152]
Next, it was kept at a temperature of 600 to 680 ° C. and a pressure of 50 to 67 Pa for 600 minutes to thermally decompose the raw material.
[0153]
Furthermore, by holding at a temperature of 30 to 35 ° C. and a pressure of 10 to 13 Pa for 600 minutes, a coating layer composed of polyparaxylylene is formed on the surface of the magnet main body. The pressure was kept at 1.3 Pa for 580 minutes.
[0154]
Finally, the temperature in the apparatus was set to room temperature and the pressure was set to atmospheric pressure, and the bonded magnet on which the coating layer was formed was taken out of the apparatus.
[0155]
The coating layer is formed by installing a roller as shown in FIG. 6 in the chamber, adjusting the rotation speed of the roller, and controlling the rotation of the magnet body, which is a work. Was performed while controlling.
[0156]
As described above, the bonded magnet on which the coating layer was formed was subjected to multi-pole magnetization to eight poles to obtain a permanent magnet (Sample No. 1).
[0157]
The maximum magnetic energy product (BH) of the permanent magnet thus obtained_maxIs 81 kJ / m³Met.
[0158]
<Sample No. 2>
In forming the coating layer, di-monochloro-para-xylylene (a dimer corresponding to polymonochloro-para-xylylene) was used as a raw material, and the formed coating layer was composed of polymonochloro-para-xylylene. Sample No. A permanent magnet (Sample No. 2) was produced in the same manner as the permanent magnet of No. 1.
[0159]
<Sample No. 3-No. 5>
Table 1 shows the average thickness Di of the coating layer on the inner peripheral surface side of the bonded magnet and the average thickness Do of the coating layer on the outer peripheral surface side of the bonded magnet by changing the CVD processing time, the roller size, and the rotation speed. Except that the sample No. was changed as shown in FIG. Three kinds of permanent magnets (Sample Nos. 3 to 5) were produced in the same manner as the permanent magnet of No. 2.
[0160]
<Sample No. 6>
Prior to forming the coating layer, the sample No. 1 had a base layer made of a bis-A epoxy resin on the entire surface of the bonded magnet so as to have a configuration as shown in FIG. A permanent magnet (Sample No. 6) was manufactured in the same manner as the permanent magnet of No. 1.
[0161]
The formation of the underlayer was performed by spray-coating an uncured bis-A type epoxy resin, and then curing it at 150 ° C. for 20 minutes. The average thickness of the formed underlayer was 5.2 μm.
[0162]
Prior to forming the coating layer, the surface of the underlayer was washed. As the cleaning of the underlayer surface, degreasing cleaning and pure water cleaning were performed. The degreasing cleaning was performed at 50 ° C. for 10 minutes using a cleaning solution in which A-Screen A-220 (a product of Okuno Pharmaceutical Market) was dissolved at a concentration of 50 g / L. The pH of this washing solution was 11.4. The pure water cleaning was performed at room temperature for 1 minute.
[0163]
<Sample No. 7-No. 9>
Except that the average thickness of the underlayer, the average thickness Di of the coating layer on the inner peripheral surface side of the bonded magnet, and the average thickness Do of the coating layer on the outer peripheral surface side of the bonded magnet were changed as shown in Table 1, Sample No. In the same manner as the permanent magnet of No. 6, three types of permanent magnets (Sample Nos. 7 to 9) were produced.
[0164]
<Sample No. 10>
Sample No. 1 was prepared except that the constituent material of the underlayer was phenol resin and the coating layer was made of polymonochloroparaxylylene. A permanent magnet (Sample No. 10) was produced in the same manner as the permanent magnet of No. 6.
[0165]
<Sample No. 11-No. 13>
Except that the average thickness of the underlayer, the average thickness Di of the coating layer on the inner peripheral surface side of the bonded magnet, and the average thickness Do of the coating layer on the outer peripheral surface side of the bonded magnet were changed as shown in Table 1, Sample No. Three kinds of permanent magnets (samples No. 11 to No. 13) were produced in the same manner as the tenth permanent magnet.
[0166]
<Sample No. 14-No. 17>
The underlayer is formed only on the inner peripheral surface side of the bond magnet so as to have a configuration as shown in FIG. 3, and the constituent material of the underlayer, the average thickness of the underlayer, and the coating layer on the inner peripheral surface side of the bond magnet are formed. Sample No. except that the average thickness Di of the coating layer and the average thickness Do of the coating layer on the outer peripheral surface side of the bonded magnet were changed as shown in Table 1. Four types of permanent magnets (Sample Nos. 14 to 17) were produced in the same manner as in the case of No. 10.
[0167]
<Sample No. 18>
Sample No. 1 was prepared except that the bonded magnet was used as a permanent magnet without forming a coating layer. A permanent magnet (Sample No. 18) was manufactured in the same manner as the permanent magnet of No. 1.
[0168]
<Sample No. 19>
Sample No. 1 was prepared except that a coating layer composed of a bis-A type epoxy resin was formed on the surface of the bonded magnet. A permanent magnet (Sample No. 19) was manufactured in the same manner as the permanent magnet of No. 1.
[0169]
The coating layer was formed by spray-coating an uncured bis-A type epoxy resin, and then curing it at 150 ° C. for 20 minutes. The average thickness of the formed underlayer was 16.2 μm.
[0170]
<Sample No. 20>
Sample No. 1 was prepared except that the average thickness Di of the coating layer on the inner peripheral surface side of the bonded magnet and the average thickness Do of the coating layer on the outer peripheral surface side of the bonded magnet were changed as shown in Table 1. A permanent magnet (Sample No. 20) was produced in the same manner as the permanent magnet of No. 1.
[0171]
Sample No. 1 to No. Table 1 shows the configuration of the coating layer and the underlayer for each of the 20 permanent magnets.
[0172]
[Table 1]

[0173]
[Evaluation of permanent magnets]
<Measurement of generated gas amount>
In addition, the sample No. 1 to No. For each of the 20 permanent magnets, the amount of generated gas was measured under the following conditions.
[0174]
First, sample no. 1 to No. For each of the twenty, five permanent magnets were prepared. These permanent magnets were subjected to pure water ultrasonic cleaning. This ultrasonic cleaning with pure water was performed at 25 ° C. for 5 minutes. Then, it dried at 80 degreeC for 30 minutes.
[0175]
Next, the magnets (5 each) of each sample were placed in a headspace bottle having a capacity of 100 mL, and heated at 70 ° C. for 16 hours. Next, He gas was flowed at a flow rate of 1 mL / min for 30 minutes as a carrier gas, and the outflowing gas was collected. Thereafter, the collected gas was analyzed by GC-MS (manufactured by Hewlett-Packard Company: trade name “5890-5971A”). Then, based on the obtained measurement result, the surface area of the permanent magnet is 1 m.²The amount of gas generated per unit was determined (measurement limit: 20 μg / m²).
[0176]
<Measurement of ion amount>
In addition, the sample No. 1 to No. With respect to each of the 20 permanent magnets, the amount of extracted ions was measured under the following conditions.
[0177]
First, sample no. 1 to No. For each of the twenty, five permanent magnets were prepared. These permanent magnets were subjected to pure water ultrasonic cleaning. This ultrasonic cleaning with pure water was performed under the condition of 25 ° C. × 3 minutes. Thereafter, drying was performed at 85 ° C. for 30 minutes.
[0178]
Next, an extraction operation was performed on the permanent magnets (five each) of each sample for 30 minutes using pure water of 80 mL and 60 mL. Next, Br was added to the water using an ion chromatograph (trade name: “IC500”, manufactured by Yokogawa Electric Corporation).⁻, NO_X ⁻, Cl⁻, PO₄ ^3-, F⁻, SO₄ ^2-, NH₄ ⁺Were analyzed and measured. Then, based on the obtained measurement result, the surface area of the permanent magnet is 1 m.²The total amount of extracted ions per unit was determined (measurement limit 5 μg / m²).
[0179]
<Measurement of radial crushing strength>
In addition, the sample No. 1 to No. The radial crushing strength of each of the 20 permanent magnets was measured. The radial crushing strength was measured according to JIS Z2507.
[0180]
<Salt spray test>
In addition, the sample No. 1 to No. For each of the 20 permanent magnets, a 24-hour exposure test was performed in accordance with the method described in JIS @ K # 5401.
[0181]
Thereafter, 10 different points on the magnet surface were observed under an 8 × microscope, and when no discoloration was observed in the visual field, the evaluation was evaluated as ◎. When partial discoloration was confirmed at one or two points, it was evaluated as ○. When three or more discolorations were confirmed, the evaluation was evaluated as Δ. When one or more red rusts were confirmed, the evaluation was evaluated as x.
Table 2 shows the results.
[0182]
[Table 2]

[0183]
As is clear from Table 2, the sample No. 1 to No. In the case of the 17 permanent magnets (all of the present invention), the amount of generated gas was extremely small, and all were below the measurement limit. In addition, the sample No. 1 to No. In the case of the 17 permanent magnets (all of the present invention), the amount of extracted ions was extremely small, and 42 mg / m 2²It was below. On the other hand, the sample No. 18, No. Nineteen permanent magnets (all comparative examples) had a large amount of generated gas and a large amount of extracted ions.
[0184]
In the measurement of the radial crushing strength, the sample No. 1 to No. It was confirmed that the 17 permanent magnets (all of the present invention) had excellent mechanical strength. On the other hand, the sample No. 18, No. Nineteen permanent magnets (all comparative examples) were inferior in mechanical strength.
[0185]
In the salt spray test, the sample No. 1 to No. In the case of the 17 permanent magnets (all of the present invention), almost no discoloration was observed, and it was confirmed that they had good rust resistance. On the other hand, the sample No. 18, No. In the case of the 19 permanent magnets (all comparative examples), discoloration and rust were clearly recognized.
[0186]
In addition, the sample No. 1 to No. With respect to 17 permanent magnets (all of the present invention), the thickness of the coating layer was measured at 12 places on the outer circumferential surface (at the outer circumferential face of the permanent magnet, divided at 30 ° in the circumferential direction around the axis of the cylinder). did. As a result, the variation in the film thickness was extremely small, and was ± 1.0% or less in each case.
[0187]
(Example 2)
[Manufacture of rotors (motor parts)]
The sample No. manufactured in Example 1 was used. 1 to No. Using each of the 20 permanent magnets, a rotor (motor component) as shown in FIG. 4 was manufactured as follows.
[0188]
First, a substantially cylindrical member made of a free-cutting steel material (SUM21) was prepared, and this was subjected to cutting to obtain a yoke. The surface roughness Ra (inner surface) of the yoke thus obtained was 1.9 μm. The thermal expansion coefficient (linear expansion coefficient) at 20 ° C. of the yoke is 11.7 [× 10^-6K^-1]Met.
[0189]
Next, the obtained yoke and the permanent magnet were joined by thermal caulking.
Bonding by thermal caulking was performed as follows.
[0190]
First, the yoke was heated to 200 ° C. on a heating table. In this state, a permanent magnet was inserted into the hollow portion of the yoke from the base end side using a jig whose position in the height direction was determined. At this time, the temperature of the permanent magnet was 20 ° C.
[0191]
Thereafter, the yoke was moved from the heating table to the cooling table, and the yoke in which the permanent magnet was inserted was cooled, and the temperature was set to 20 ° C.
[0192]
As a result, the sample No. 1 to No. 17, No. In the case of using the permanent magnet of No. 20, a joined body in which the yoke and the permanent magnet were firmly joined was obtained. In addition, the sample No. 18, No. In the case of using the 19 permanent magnets, minute cracks occurred in the permanent magnets due to shrinkage of the yoke due to cooling.
[0193]
A rotor (motor component) as shown in FIG. 4 was obtained using the joined body of the permanent magnet and the yoke obtained as described above. In addition, as a constituent material of the yoke, the hub, and the sleeve, free-cutting steel (SUM21), aluminum, and brass were used, respectively, and the joining between the yoke and the hub and the joining between the hub and the sleeve were all performed by press fitting. .
[0194]
For each rotor, the dimensions of the bonded magnet used for manufacturing (the dimensions in the natural state at room temperature (20 ° C.): outer diameter × inner diameter (excluding the vicinity of the tip) × height), and the dimensions of the yoke (room temperature (20 ° C.)) Table 3 shows the dimensions in the natural state of the above: outer diameter × inner diameter (excluding the vicinity of the tip) × height) and inner diameter of the yoke in the heated state.
[0195]
[Table 3]

[0196]
[Evaluation of rotor and manufacture of motor]
For each of the rotors manufactured as described above, the rotational unbalance amount was measured using a dynamic balance tester (VC # 003T type) manufactured by Shimadzu Corporation. The rotation speed at that time was 3600 rpm.
Table 4 shows the measurement results of the rotational unbalance amount.
[0197]
[Table 4]

[0198]
From Table 4, sample No. 1 to No. It can be seen that the rotor 17 (all of the present invention) has an extremely small rotational imbalance. On the other hand, the sample No. 18-No. In the rotor of No. 20 (both comparative examples), the rotational unbalance amount is large. Among them, sample No. The rotor No. 20 had a very large rotational unbalance.
[0199]
Next, the sample No. 1 to No. Using the rotor according to No. 20, a motor as shown in FIG.
[0200]
The operation of energizing the coils of the stator (energization time: 30 seconds, maximum rotation speed: 7200 rpm) was repeatedly performed for each of the motors thus obtained.
[0201]
Sample No. 1 to No. In the motor according to No. 17 (all of the present invention), the vibration and noise during driving were relatively small. 18-No. In the case of the motor No. 20 (both comparative examples), vibration and noise during driving were large. In the motor of the comparative example, the vibration and noise at the time of driving were large because the thickness of the coating layer was large, the unbalance amount of the rotor was large, and the permanent magnet was lost or damaged at the time of heat caulking. This is considered to be due to the fact that the unbalance amount of the rotor was large.
[0202]
In addition, the sample No. 18-No. With the motor No. 20 (both comparative examples), the vibration and noise (abnormal noise) became more intense from the time when the number of times of the energization operation reached about 30,000.
[0203]
After performing the above-mentioned energization operation 50,000 times, each motor was disassembled. The rotors were taken out of the disassembled motors, and the rotors were subjected to a 24-hour exposure test according to the method described in JIS K # 5401.
[0204]
As a result, the sample No. 18, No. In the rotor No. 19 (all comparative examples), discoloration due to red rust and the like was clearly observed around the permanent magnet. On the other hand, the sample No. 1 to No. In the rotor No. 17 (all of the present invention), no discoloration due to rust or the like was observed around the permanent magnet.
[0205]
(Example 3)
[Manufacture of rotors (motor parts)]
The sample No. manufactured in Example 1 was used. 1 to No. Using each of the 20 permanent magnets, a rotor (motor component) as shown in FIG. 4 was manufactured as follows.
[0206]
First, a substantially cylindrical member made of a free-cutting steel material (SUM21) was prepared, and this was subjected to cutting to obtain a yoke. The surface roughness Ra (inner surface) of the yoke thus obtained was 1.9 μm. The thermal expansion coefficient (linear expansion coefficient) at 20 ° C. of the yoke is 11.7 [× 10^-6K^-1]Met.
[0207]
Next, a permanent magnet was pressed into the hollow portion of the obtained yoke. The press-fitting of the permanent magnet was performed by a hydraulic press using a positioning jig such that the permanent magnet did not tilt with respect to the yoke. At this time, the relative moving speed (approach speed) between the permanent magnet and the yoke was 5 cm / sec.
[0208]
Sample No. 1 to No. In the case of using the permanent magnet of No. 17, the press-fitting operation can be performed smoothly, and the joined body of the permanent magnet and the yoke obtained by the press-fitting has the permanent magnet and the yoke joined very firmly. Met. In addition, the sample No. In the case of using the permanent magnet of No. 18, a part of the bonded magnet was cut off when an attempt was made to join by press fitting. In addition, the sample No. In the case of using the permanent magnet of No. 19, joining was attempted by press-fitting, but a part of the coating was cut off, and a part of the magnet body was exposed.
[0209]
A rotor (motor component) as shown in FIG. 4 was obtained using the joined body of the permanent magnet and the yoke obtained as described above. In addition, as a constituent material of the yoke, the hub, and the sleeve, free-cutting steel (SUM21), aluminum, and brass are used, respectively. Performed by heat caulking.
[0210]
For each rotor, the dimensions of the bonded magnet used for manufacture (the dimensions in the natural state at room temperature (20 ° C.): outer diameter × inner diameter (excluding the vicinity of the tip) × height), and the dimensions of the yoke (room temperature (20 ° C.)) Table 5 shows the dimensions in the natural state of the above: outer diameter × inner diameter (excluding the vicinity of the tip) × height) and the inner diameter of the yoke in the heated state.
[0211]
[Table 5]

[0212]
[Evaluation of rotor and manufacture of motor]
For each of the rotors manufactured as described above, the rotational unbalance amount was measured using a dynamic balance tester (VC # 003T type) manufactured by Shimadzu Corporation. The rotation speed at that time was 3600 rpm.
Table 6 shows the measurement results of the rotational unbalance amount.
[0213]
[Table 6]

[0214]
From Table 6, Sample No. 1 to No. It can be seen that the rotor 17 (all of the present invention) has an extremely small rotational imbalance. On the other hand, the sample No. 19, no. In the rotor of No. 20 (both comparative examples), the rotational unbalance amount is large.
[0215]
Next, the sample No. 1 to No. Using the rotor according to No. 20, a motor as shown in FIG.
[0216]
The operation of energizing the coils of the stator (energization time: 30 seconds, maximum rotation speed: 7200 rpm) was repeatedly performed for each of the motors thus obtained.
[0219]
Sample No. 1 to No. In the motor according to No. 17 (all of the present invention), the vibration and noise during driving were relatively small. 19, no. In the case of the motor No. 20 (both comparative examples), vibration and noise during driving were large.
[0218]
In addition, the sample No. 19, no. With the motor No. 20 (both comparative examples), the vibration and noise (abnormal noise) became more intense from the time when the number of times of the energization operation reached about 30,000.
[0219]
After performing the above-mentioned energization operation 50,000 times, each motor was disassembled. The rotors were taken out of the disassembled motors, and each of these rotors was subjected to a 24-hour exposure test according to the method described in JIS K # 5401.
[0220]
As a result, the sample No. 18, No. In the rotor No. 19 (all comparative examples), discoloration due to red rust and the like was clearly observed around the permanent magnet. On the other hand, the sample No. 1 to No. In the rotor No. 17 (all of the present invention), no discoloration due to rust or the like was observed around the permanent magnet.
[0221]
Further, except that the formation of the coating layer was changed to the method shown in the above [1] and [3], a permanent magnet was manufactured in the same manner as above, and the same evaluation as in Examples 1 to 3 was performed. Was. As a result, in each case, the same result as described above was obtained.
[0222]
【The invention's effect】
As described above, according to the present invention, it is possible to provide a permanent magnet, a motor component, and a motor that hardly adversely affect devices such as a hard disk drive.
[0223]
In particular, by satisfying the relationship Di> Do between the thickness Di of the coating layer on the inner peripheral surface side of the magnet main body and the thickness Do of the coating layer on the outer peripheral surface side of the magnet main body, And the generation of vibration and noise (abnormal noise) during motor driving due to shaft deviation can be effectively prevented. In addition, it is possible to prevent the permanent magnet from being damaged or damaged when the motor is assembled. Therefore, it can be suitably applied to a high-rotation type motor or the like, and can contribute to higher performance and higher density of a device such as a hard disk drive, for example.
[Brief description of the drawings]
FIG. 1 is a sectional perspective view showing a first embodiment of a permanent magnet of the present invention.
FIG. 2 is a sectional perspective view showing a second embodiment of the permanent magnet of the present invention.
FIG. 3 is a sectional perspective view showing another embodiment of the permanent magnet of the present invention.
FIG. 4 is a sectional side view showing a preferred embodiment of a motor component (rotor) of the present invention.
FIG. 5 is a sectional side view showing a preferred embodiment of a motor having the motor parts shown in FIG. 4;
FIG. 6 is a side view schematically showing an example of a configuration of an apparatus used for forming a coating layer.
[Explanation of symbols]
1 ... permanent magnet # 11 ... magnet body # 12 ... coating layer # 13 ... base layer # 3 ... rotor # 31 ... hub # 32 ... sleeve # 321 ... bearing part # 322 ... bearing part # 323 ... ... groove # 33 ... yoke 4 Motor # 41 Shaft # 42 Stator # 421 Core # 422 Coil # 43 Base # 44 Flange # 45 Thrust receiving plate # 5 Roller # 6 Roller # 7 Roller # 8 Shielding Board

Claims (23)

A permanent magnet having a substantially cylindrical magnet main body and a coating layer provided on the surface side thereof,
The coating layer is mainly composed of polyparaxylylene resin,
When the average thickness of the coating layer on the inner peripheral surface side of the magnet main body is Di [μm] and the average thickness of the coating layer on the outer peripheral surface side of the magnet main body is Do [μm], Di> Do A permanent magnet characterized by satisfying the relationship. The permanent magnet according to claim 1, wherein an average thickness Di of the coating layer on the inner peripheral surface side of the magnet main body is 15 to 35 m. The permanent magnet according to claim 1, wherein an average thickness Do of the coating layer on the outer peripheral surface side of the magnet main body is less than 15 μm. 4. The permanent magnet according to claim 1, wherein the polyparaxylylene resin contains at least one of polymonochloroparaxylylene and polyparaxylylene. The permanent magnet according to any one of claims 1 to 4, wherein the coating layer is formed by a chemical vapor deposition method. The permanent magnet according to any one of claims 1 to 5, further comprising a base layer between the magnet main body and the coating layer. The permanent magnet according to claim 6, wherein the underlayer is mainly formed of an organic polymer material. The permanent magnet according to claim 6, wherein an average thickness of the underlayer is 10 μm or less. The permanent magnet according to any one of claims 1 to 8, wherein the amount of gas generated for 16 hours at 70 ° C is 50 mg or less per 1 m ^{2 of} surface area. When immersed for 30 minutes in pure water at 80 ° C., ^Br extracted _{^{-, NO X -, Cl -}} , PO 4 3-, F -, SO 4 2-, NH 4 + amount of total is, the surface area 1m The permanent magnet according to any one of claims 1 to 9, wherein the amount of the permanent magnet is 150 mg or less per ² pieces. The permanent magnet according to any one of claims 1 to 10, wherein the porosity of the magnet main body is 7.0 vol% or less. The permanent magnet according to any one of claims 1 to 11, wherein the magnet main body is a bonded magnet formed by bonding magnet powder with a bonding resin. The permanent magnet according to claim 12, wherein the magnet powder has a composition containing a rare earth element, a transition metal, and boron. 14. The permanent magnet according to claim 12, wherein the content ratio of the magnet powder in the bonded magnet is 93 to 99 wt%. The permanent magnet according to any one of claims 1 to 14, wherein the magnet main body is chamfered. A permanent magnet according to any one of claims 1 to 15,
A motor component comprising: a support member that supports the permanent magnet. 17. The motor component according to claim 16, wherein the permanent magnet is supported and fixed on an inner peripheral side of the support member. 18. The motor component according to claim 16, wherein the permanent magnet is supported and fixed to an inner peripheral side of the support member by press-fitting. 19. The motor component according to claim 16, wherein the motor component is a rotor. 20. The motor component according to claim 19, wherein a rotational unbalance amount of the rotor is 0.05 g · cm or less. A motor comprising the motor component according to any one of claims 16 to 20. The motor according to claim 21, which is used for a hard disk drive. The motor according to claim 21 or 22, wherein the motor is used in a region where the maximum rotation speed is 3600 rpm or more.

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