JP2021057488A - Manufacturing method of cylindrical bond magnet, cylindrical bond magnet molding die, and cylindrical bond magnet - Google Patents
Manufacturing method of cylindrical bond magnet, cylindrical bond magnet molding die, and cylindrical bond magnet Download PDFInfo
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Abstract
Description
本発明は、円筒状ボンド磁石の製造方法、円筒状ボンド磁石成形用金型、および円筒状ボンド磁石に関する。 The present invention relates to a method for manufacturing a cylindrical bond magnet, a mold for forming a cylindrical bond magnet, and a cylindrical bond magnet.
モーター等の動力用に、円筒状の多極ボンド磁石が用いられる。このような円筒状ボンド磁石は、配向用磁石を備えた金型にボンド磁石用組成物を注入して射出成形することにより製造される。円筒状ボンド磁石の磁極間の表面磁束密度の変化が急峻であると、モーターに適用したときにコギングを生じる原因となるため、円筒状ボンド磁石は正弦波曲線に近い表面磁束密度を有することが求められる。また、大型モーターに対応するために、円筒状ボンド磁石を大径化することも求められている。 Cylindrical multi-pole bond magnets are used to power motors and the like. Such a cylindrical bond magnet is manufactured by injecting a composition for a bond magnet into a mold provided with an alignment magnet and injection molding. A steep change in the surface magnetic flux density between the magnetic poles of a cylindrical bond magnet causes cogging when applied to a motor, so the cylindrical bond magnet may have a surface magnetic flux density close to a sinusoidal curve. Desired. It is also required to increase the diameter of the cylindrical bond magnet in order to support a large motor.
特許文献１は、円筒状キャビティの外側に配向用磁石を配置した金型を用いて、射出成形によりリング状ボンド磁石を製造している。製造されたボンド磁石は、外周径が１６ｍｍ程度と小型である。
特許文献２〜３は、円筒状キャビティの内側に、複数の配向用磁石をそれぞれの磁場が円周方向に互いに反発するように配置した金型を用いて、射出成形により円筒状ボンド磁石を製造している。製造されたボンド磁石は外周径が大きいものでも４２ｍｍ程度である。特許文献３では配向用磁石とボンド磁石成形体との間に厚さ０．５ｍｍのスリーブを配置して磁場配向しているが、この条件では配向用磁石との距離が近すぎるために、ボンド磁石成形体の磁極間の表面磁束密度の変化が急峻となる傾向がある。
In
本発明は、大径で、正弦波曲線またはそれに近似した表面磁束密度を有する円筒状ボンド磁石の製造方法、その製造方法に用いる金型、および円筒状ボンド磁石を提供することを目的とする。 An object of the present invention is to provide a method for manufacturing a cylindrical bond magnet having a large diameter and a sinusoidal curve or a surface magnetic flux density close thereto, a mold used for the manufacturing method, and a cylindrical bond magnet.
本発明の一態様にかかる円筒状ボンド磁石の製造方法は、円筒状キャビティを有し、配向用磁石が配置された金型を射出成形機に配置する工程と、前記金型にボンド磁石用組成物を注入して射出成形する工程とを含む、円筒状ボンド磁石の製造方法であって、前記円筒状キャビティの内周部と前記配向用磁石の外周部との最短ギャップが２ｍｍ以上１０ｍｍ以下であり、前記円筒状キャビティは、外周直径が１００ｍｍ以上３００ｍｍ以下であって、外周半径と内周半径の差が２ｍｍ以上３０ｍｍ以下であって、前記配向用磁石は、円周方向に磁化された複数の扇形平板磁石から構成され、扇形平板磁石は、隣り合う扇形平板磁石の磁場方向がそれぞれ円周方向に互いに反発するように円周方向に配置されていることを特徴とする。 The method for manufacturing a cylindrical bond magnet according to one aspect of the present invention includes a step of arranging a mold having a cylindrical cavity and an alignment magnet arranged in an injection molding machine, and a composition for a bond magnet in the mold. A method for manufacturing a cylindrical bond magnet, which includes a step of injecting an object and injection molding, in which the shortest gap between the inner peripheral portion of the cylindrical cavity and the outer peripheral portion of the alignment magnet is 2 mm or more and 10 mm or less. The cylindrical cavity has an outer peripheral diameter of 100 mm or more and 300 mm or less, and the difference between the outer peripheral radius and the inner peripheral radius is 2 mm or more and 30 mm or less. The fan-shaped flat plate magnets are composed of the above fan-shaped flat plate magnets, and are characterized in that they are arranged in the circumferential direction so that the magnetic field directions of adjacent fan-shaped flat plate magnets repel each other in the circumferential direction.
本発明の一態様にかかる円筒状ボンド磁石成形用金型は、円周方向に磁化された複数の扇形平板磁石を、各扇形平板磁石の磁場方向がそれぞれ円周方向に互いに反発する方向に周方向に配置した配向用磁石、および、円筒状キャビティを有し、該配向用磁石の外周部と円筒状キャビティの内周部の最短ギャップが２ｍｍ以上１０ｍｍ以下であり、円筒状キャビティの外周直径が１００ｍｍ以上３００ｍｍ以下であり、外周半径と内周半径の差が２ｍｍ以上３０ｍｍ以下である。 The cylindrical bond magnet molding mold according to one aspect of the present invention surrounds a plurality of fan-shaped flat plate magnets magnetized in the circumferential direction in a direction in which the magnetic field directions of the fan-shaped flat plate magnets repel each other in the circumferential direction. It has an alignment magnet arranged in the direction and a cylindrical cavity, and the shortest gap between the outer peripheral portion of the alignment magnet and the inner peripheral portion of the cylindrical cavity is 2 mm or more and 10 mm or less, and the outer peripheral diameter of the cylindrical cavity is It is 100 mm or more and 300 mm or less, and the difference between the outer peripheral radius and the inner peripheral radius is 2 mm or more and 30 mm or less.
本発明の一態様にかかる円筒状ボンド磁石は、内周側の表面磁束密度が周期的に変動し、該表面磁束密度の正弦波曲線に対する歪率が２２％以下であって、外周直径が１００ｍｍ以上３００ｍｍ以下であり、外周半径と内周半径の差が２ｍｍ以上３０ｍｍ以下である。 In the cylindrical bond magnet according to one aspect of the present invention, the surface magnetic flux density on the inner peripheral side fluctuates periodically, the strain rate of the surface magnetic flux density with respect to the sinusoidal curve is 22% or less, and the outer peripheral diameter is 100 mm. It is 300 mm or less, and the difference between the outer peripheral radius and the inner peripheral radius is 2 mm or more and 30 mm or less.
本発明の一態様にかかる円筒状ボンド磁石成形用金型によると、大径で、正弦波曲線またはそれに近似した表面磁束密度を有する円筒状ボンド磁石を製造することができる。 According to the cylindrical bond magnet molding die according to one aspect of the present invention, it is possible to manufacture a cylindrical bond magnet having a large diameter and a surface magnetic flux density of a sinusoidal curve or a surface magnetic flux density close thereto.
以下、本発明の実施形態について詳述する。ただし、以下に示す実施形態は、本発明の技術思想を具体化するための一例であり、本発明を以下のものに限定するものではない。なお、本明細書において「工程」との語は、独立した工程だけではなく、他の工程と明確に区別できない場合であってもその工程の所期の目的が達成されれば、本用語に含まれる。また「〜」を用いて示された数値範囲は、「〜」の前後に記載される数値をそれぞれ最小値及び最大値として含む範囲を示す。さらに組成物中の各成分の含有量は、組成物中に各成分に該当する物質が複数存在する場合、特に断らない限り、組成物中に存在する当該複数の物質の合計量を意味する。 Hereinafter, embodiments of the present invention will be described in detail. However, the embodiments shown below are examples for embodying the technical idea of the present invention, and the present invention is not limited to the following. In this specification, the term "process" is used not only for an independent process but also for the term "process" as long as the intended purpose of the process is achieved even if it cannot be clearly distinguished from other processes. included. Further, the numerical range indicated by using "~" indicates a range including the numerical values before and after "~" as the minimum value and the maximum value, respectively. Further, the content of each component in the composition means the total amount of the plurality of substances present in the composition when a plurality of substances corresponding to each component are present in the composition, unless otherwise specified.
＜＜円筒状ボンド磁石の製造方法＞＞
本発明の一態様にかかる円筒状ボンド磁石の製造方法は、円筒状キャビティを有し、配向用磁石が配置された金型を射出成形機に配置する工程と、前記金型にボンド磁石用組成物を注入して射出成形する工程とを含む、円筒状ボンド磁石の製造方法であって、前記円筒状キャビティの内周部と前記配向用磁石の外周部との最短ギャップが２ｍｍ以上１０ｍｍ以下であり、前記円筒状キャビティは、外周直径が１００ｍｍ以上３００ｍｍ以下であって、外周半径と内周半径の差が２ｍｍ以上３０ｍｍ以下であって、前記配向用磁石は、円周方向に磁化された複数の扇形平板磁石から構成され、扇形平板磁石は、隣り合う扇形平板磁石の磁場方向がそれぞれ円周方向に互いに反発するように円周方向に配置されていることを特徴とする。本発明の一態様によると円筒状キャビティの内周部と配向用磁石の外周部との最短ギャップが２ｍｍ以上１０ｍｍ以下とし、配向用磁石が、円周方向に磁化された複数の扇形平板磁石から構成され、扇形平板磁石は、隣り合う扇形平板磁石の磁場方向がそれぞれ円周方向に互いに反発するように円周方向に配置されることにより、キャビティ内に発生する磁場が磁極部で最大となりつつ、かつ磁極間の切り替わりがゆるやかになるため、大径で、正弦波曲線またはそれに近似した表面磁束密度を有する円筒状ボンド磁石を製造することができると考えられる。
<< Manufacturing method of cylindrical bond magnet >>
The method for manufacturing a cylindrical bond magnet according to one aspect of the present invention includes a step of arranging a mold having a cylindrical cavity and an alignment magnet arranged in an injection molding machine, and a composition for a bond magnet in the mold. A method for manufacturing a cylindrical bond magnet, which includes a step of injecting an object and injection molding, in which the shortest gap between the inner peripheral portion of the cylindrical cavity and the outer peripheral portion of the alignment magnet is 2 mm or more and 10 mm or less. The cylindrical cavity has an outer peripheral diameter of 100 mm or more and 300 mm or less, and the difference between the outer peripheral radius and the inner peripheral radius is 2 mm or more and 30 mm or less. The fan-shaped flat plate magnets are composed of the above fan-shaped flat plate magnets, and are characterized in that they are arranged in the circumferential direction so that the magnetic field directions of adjacent fan-shaped flat plate magnets repel each other in the circumferential direction. According to one aspect of the present invention, the shortest gap between the inner peripheral portion of the cylindrical cavity and the outer peripheral portion of the alignment magnet is 2 mm or more and 10 mm or less, and the alignment magnet is formed from a plurality of fan-shaped flat plate magnets magnetized in the circumferential direction. The fan-shaped flat plate magnets are configured so that the magnetic field directions of adjacent fan-shaped flat plate magnets are arranged in the circumferential direction so as to repel each other in the circumferential direction, so that the magnetic field generated in the cavity is maximized at the magnetic pole portion. In addition, since the switching between the magnetic poles becomes gentle, it is considered that a cylindrical bond magnet having a large diameter and a surface magnetic flux density close to that of a sinusoidal curve can be manufactured.
＜金型＞
本発明の一態様で用いる金型は、円筒状キャビティを有する。正弦波曲線またはそれに近似した表面磁束密度を有する大径の円筒状ボンド磁石を製造するためには、前記円筒状キャビティは、外周直径（円筒状ボンド磁石の外径）が１００ｍｍ以上３００ｍｍ以下であるが、外周直径が１５０ｍｍ以上３００ｍｍ未満であることが好ましく、２００ｍｍ以上２９０ｍｍ以下であることが特に好ましい。また、円筒状キャビティの外周半径と内周半径の差（円筒状ボンド磁石の肉厚）は２ｍｍ以上３０ｍｍ以下であるが、肉薄にすることによる軽量化の点から２ｍｍより大きく１０ｍｍ以下であることが好ましく、２．５ｍｍ以上５ｍｍ以下が特に好ましい。２ｍｍ未満では円筒状ボンド磁石の強度が低下し、３０ｍｍより大きくなると、成形時に部分的に樹脂の冷却スピードにばらつきが生じるため寸法精度が低下することがある。円筒状キャビティの高さ（円筒状ボンド磁石の高さ）は、５ｍｍ以上１００ｍｍ以下であるが、６ｍｍ以上１５ｍｍ以下が好ましい。５ｍｍ未満では外周方向の総磁束量が小さくなり、１００ｍｍより大きくすると、成形時に部分的に樹脂の冷却スピードにばらつきが生じるため寸法精度が低下することがある。円筒状キャビティの外周半径に対する外周半径と内周半径の差の比は、大径の円筒状ボンド磁石の強度の点から、０．０１以上０．８以下が好ましく、０．０４以上０．６以下がより好ましい。
<Mold>
The mold used in one aspect of the present invention has a cylindrical cavity. In order to manufacture a large-diameter cylindrical bond magnet having a sinusoidal curve or a surface magnetic flux density close thereto, the cylindrical cavity has an outer peripheral diameter (outer diameter of the cylindrical bond magnet) of 100 mm or more and 300 mm or less. However, the outer peripheral diameter is preferably 150 mm or more and less than 300 mm, and particularly preferably 200 mm or more and 290 mm or less. The difference between the outer peripheral radius and the inner peripheral radius of the cylindrical cavity (thickness of the cylindrical bond magnet) is 2 mm or more and 30 mm or less, but it is larger than 2 mm and 10 mm or less from the viewpoint of weight reduction by making the thickness thinner. Is preferable, and 2.5 mm or more and 5 mm or less is particularly preferable. If it is less than 2 mm, the strength of the cylindrical bond magnet is lowered, and if it is larger than 30 mm, the cooling speed of the resin is partially varied during molding, so that the dimensional accuracy may be lowered. The height of the cylindrical cavity (height of the cylindrical bond magnet) is 5 mm or more and 100 mm or less, but 6 mm or more and 15 mm or less is preferable. If it is less than 5 mm, the total magnetic flux amount in the outer peripheral direction becomes small, and if it is larger than 100 mm, the cooling speed of the resin partially varies during molding, so that the dimensional accuracy may decrease. The ratio of the difference between the outer peripheral radius and the inner peripheral radius to the outer peripheral radius of the cylindrical cavity is preferably 0.01 or more and 0.8 or less, preferably 0.04 or more and 0.6, from the viewpoint of the strength of the large-diameter cylindrical bond magnet. The following is more preferable.
前記寸法の円筒状キャビティにより、大径の円筒状ボンド磁石を製造できる。特に円筒状ボンド磁石を大径で肉薄とすると、軽量でかつ１００００ｒｐｍ以上の高速回転にも耐えうるモーター用の磁石を提供できる。 With the cylindrical cavity of the above dimensions, a large-diameter cylindrical bond magnet can be manufactured. In particular, if the cylindrical bond magnet has a large diameter and is thin, it is possible to provide a magnet for a motor that is lightweight and can withstand high-speed rotation of 10,000 rpm or more.
金型は、円筒状キャビティで形成されるボンド磁石に配向磁場を印加できるように、円筒状キャビティの内側に配向用磁石を有する。配向用磁石は、円周方向に磁化された複数の扇形平板磁石から構成される。扇形平板磁石としては永久磁石、電磁石が挙げられるが、回路が不要であることから永久磁石が好ましい。扇形平板磁石の表面磁束密度は特に限定されず、円筒状ボンド磁石の配向に必要な磁場により適宜決定できるが、通常０．５Ｔ以上２Ｔ以下である。 The mold has an alignment magnet inside the cylindrical cavity so that an alignment magnetic field can be applied to the bond magnet formed in the cylindrical cavity. The alignment magnet is composed of a plurality of fan-shaped flat plate magnets magnetized in the circumferential direction. Examples of the fan-shaped flat plate magnet include a permanent magnet and an electromagnet, but a permanent magnet is preferable because a circuit is not required. The surface magnetic flux density of the fan-shaped flat plate magnet is not particularly limited and can be appropriately determined by the magnetic field required for the orientation of the cylindrical bond magnet, but is usually 0.5 T or more and 2 T or less.
円筒状キャビティの内周部と、配向用磁石の外周部との最短ギャップ（スリーブ厚さ）は２ｍｍ以上１０ｍｍ以下であり、３ｍｍ以上９ｍｍ以下が好ましく、４ｍｍ以上８ｍｍ以下がより好ましい。前述の円筒状キャビティの寸法に対して、円筒状キャビティの内周部と、配向用磁石の外周部との最短ギャップを２ｍｍ以上１０ｍｍ以下とすることで、正弦波曲線またはそれに近似した表面磁束密度を有する大径の円筒状ボンド磁石を得ることができる。 The shortest gap (sleeve thickness) between the inner peripheral portion of the cylindrical cavity and the outer peripheral portion of the alignment magnet is 2 mm or more and 10 mm or less, preferably 3 mm or more and 9 mm or less, and more preferably 4 mm or more and 8 mm or less. By setting the shortest gap between the inner peripheral portion of the cylindrical cavity and the outer peripheral portion of the alignment magnet to 2 mm or more and 10 mm or less with respect to the above-mentioned dimensions of the cylindrical cavity, a sinusoidal curve or a surface magnetic flux density close to it is set. A large-diameter cylindrical bond magnet having the above can be obtained.
円筒状ボンド磁石に磁極を均等に形成させるために、配向用磁石は複数の同一形状の扇形平板磁石から構成されることが好ましい。配向用磁石を構成する扇形平板磁石の個数は、４個以上５６個以下とすることができ、６個以上３０個以下が好ましい。配向用磁石は扇形平板磁石のみから構成されてもよいが、扇形平板磁石に加えて、磁性スペーサーや、非磁性スペーサーを有していてもよい。磁性スペーサーや非磁性スペーサーを扇形平板磁石と交互に配置することにより、配向用磁石を容易に配置することができる。磁性スペーサーや、非磁性スペーサーは、扇形平板磁石と同一形状であることが好ましい。磁性スペーサーの飽和磁束密度は１．２Ｔ以上が好ましい。 In order to form the magnetic poles evenly on the cylindrical bond magnet, it is preferable that the alignment magnet is composed of a plurality of fan-shaped flat plate magnets having the same shape. The number of fan-shaped flat plate magnets constituting the alignment magnet can be 4 or more and 56 or less, preferably 6 or more and 30 or less. The alignment magnet may be composed of only a fan-shaped flat plate magnet, but may have a magnetic spacer or a non-magnetic spacer in addition to the fan-shaped flat plate magnet. By arranging the magnetic spacers and the non-magnetic spacers alternately with the fan-shaped flat plate magnets, the alignment magnets can be easily arranged. The magnetic spacer and the non-magnetic spacer preferably have the same shape as the fan-shaped flat plate magnet. The saturation magnetic flux density of the magnetic spacer is preferably 1.2 T or more.
配向用磁石を構成する扇形平板磁石の中心角は１０°以上９０°以下とすることができ、２０°以上６０°以下が好ましい。また、この扇形平板磁石を構成するうえで、２本の辺にて構成する扇形の１辺の長さは、円筒状キャビティの外周直径から円筒状キャビティの内周部と、配向用磁石の外周部との最短ギャップを引いた値の二分の一以下とすることができる。 The central angle of the fan-shaped flat plate magnet constituting the alignment magnet can be 10 ° or more and 90 ° or less, preferably 20 ° or more and 60 ° or less. Further, in constructing this fan-shaped flat plate magnet, the length of one side of the sector composed of two sides is determined from the outer peripheral diameter of the cylindrical cavity to the inner peripheral portion of the cylindrical cavity and the outer peripheral portion of the alignment magnet. It can be less than half of the value obtained by subtracting the shortest gap from the part.
扇形平板磁石は、隣り合う扇形平板磁石の磁場方向がそれぞれ円周方向に互いに反発するように円周方向に配置されていることを特徴とする。なお、上述のように磁性スペーサ―や非磁性スペーサーを用いる場合、隣り合う扇形平板磁石とは、磁性スペーサ―や非磁性スペーサーで隔てられた扇形平板磁石のことをいう。磁場方向が円周方向に反発することにより、扇形平板磁石のＳ極同士が相対する部分では配向用磁石の中心に向かう磁場回路が形成され、扇形平板磁石のＮ極同士が相対する部分では配向用磁石の外側に向かう磁場回路が形成される。扇形平板磁石の磁場方向の模式図を、図１Ａに示す。 The fan-shaped flat plate magnets are characterized in that they are arranged in the circumferential direction so that the magnetic field directions of adjacent fan-shaped flat plate magnets repel each other in the circumferential direction. When a magnetic spacer or a non-magnetic spacer is used as described above, the adjacent fan-shaped flat plate magnets are fan-shaped flat plate magnets separated by a magnetic spacer or a non-magnetic spacer. When the magnetic field direction repels in the circumferential direction, a magnetic field circuit is formed toward the center of the alignment magnet at the portion where the S poles of the fan-shaped flat plate magnet face each other, and the orientation at the portion where the north poles of the fan-shaped flat plate magnet face each other. A magnetic field circuit is formed toward the outside of the magnet. A schematic diagram of the magnetic field direction of the fan-shaped flat plate magnet is shown in FIG. 1A.
＜射出成形＞
上述の金型を射出成形機に配置し、ボンド磁石用組成物を金型に注入して射出成形することにより、円筒状ボンド磁石が得られる。熱処理しながら配向磁場を印加することによりボンド磁石の磁化容易軸を揃えることができる。射出成形の条件は特に限定されず、使用するボンド磁石用組成物に応じて適宜決定する。配向工程における配向磁場の大きさは、例えば極中心で０．１Ｔ以上、好ましくは、０．２Ｔ以上である。配向後、極数に応じた着磁ヨークを用い、着磁することにより、ボンド磁石を得ることができる。着磁工程における着磁磁場の大きさは、例えば１．５Ｔ以上あることが望ましい。
<Injection molding>
A cylindrical bond magnet can be obtained by arranging the above-mentioned mold in an injection molding machine, injecting the composition for a bond magnet into the mold, and performing injection molding. By applying an orientation magnetic field during heat treatment, the easily magnetized axes of the bond magnets can be aligned. The conditions for injection molding are not particularly limited, and are appropriately determined according to the composition for the bonded magnet to be used. The magnitude of the alignment magnetic field in the alignment step is, for example, 0.1 T or more, preferably 0.2 T or more at the polar center. After orientation, a bonded magnet can be obtained by magnetizing using a magnetizing yoke according to the number of poles. The magnitude of the magnetizing magnetic field in the magnetizing step is preferably 1.5 T or more, for example.
＜ボンド磁石用組成物＞
ボンド磁石用組成物は特に限定されず、例えば、熱可塑性樹脂と磁性粒子から構成される組成物が挙げられる。熱可塑性樹脂と磁性粒子を十分に混練し、得られた混練物を単軸混練機、二軸混練機等の混練機に投入し、冷却後、適当な大きさに切断することで得られる。
<Composition for bond magnet>
The composition for a bonded magnet is not particularly limited, and examples thereof include a composition composed of a thermoplastic resin and magnetic particles. It is obtained by sufficiently kneading the thermoplastic resin and the magnetic particles, putting the obtained kneaded product into a kneader such as a single-screw kneader or a twin-screw kneader, cooling the mixture, and then cutting the kneaded material into an appropriate size.
熱可塑性樹脂としては、例えば、ポリプロピレン、ポリエチレン、ポリ塩化ビニル、ポリエステル、ポリアミド、ポリカーボネート、ポリフェニレンサルファイド、アクリル樹脂などが挙げられる。その中でもポリアミド、特にポリアミド１２が好ましい。ポリアミド１２は、比較的低融点で、吸水率が低く、結晶性樹脂であるため成形性が良い。また、これらを適宜混合して使用することも可能である。 Examples of the thermoplastic resin include polypropylene, polyethylene, polyvinyl chloride, polyester, polyamide, polycarbonate, polyphenylene sulfide, and acrylic resin. Among them, polyamide, particularly polyamide 12, is preferable. Polyamide 12 has a relatively low melting point, a low water absorption rate, and is a crystalline resin, so that it has good moldability. It is also possible to mix and use these as appropriate.
磁性粒子としては、フェライト系と、希土類系であるＮｄ−Ｆｅ−Ｂ系、Ｓｍ−Ｃｏ系、Ｓｍ−Ｆｅ−Ｎ系とが挙げられる。中でも、Ｓｍ−Ｆｅ−Ｎ系を用いることが好ましい。Ｓｍ−Ｆｅ−Ｎ系は、一般的にＳｍ２Ｆｅ１７Ｎ３で表される。Ｓｍ−Ｆｅ−Ｎ系は、フェライト系に比べると磁力が強く、比較的少ない量でも高磁力を発生することができる。また、Ｓｍ−Ｆｅ−Ｎ系は、Ｎｄ−Ｆｅ−Ｂ系やＳｍ−Ｃｏ系といった他の希土類系と比べると、粒子径が小さく、母材樹脂へのフィラーとして適していることや、錆びにくいという特長がある。 Examples of the magnetic particles include ferritic stainless steel and rare earth Nd-Fe-B type, Sm-Co type, and Sm-Fe-N type. Above all, it is preferable to use the Sm-Fe-N system. The Sm-Fe-N system is generally represented by Sm 2 Fe 17 N 3 . The Sm-Fe-N system has a stronger magnetic force than the ferrite system, and can generate a high magnetic force even with a relatively small amount. In addition, the Sm-Fe-N system has a smaller particle size than other rare earth systems such as Nd-Fe-B system and Sm-Co system, is suitable as a filler for the base metal resin, and is less likely to rust. There is a feature.
磁性粒子は、異方性のもの及び等方性のもののいずれか一方又は両方を用いることができる。より強力な磁気特性を得る観点から、異方性のもの（異方性磁性粒子）が好ましい。具体的には、異方性を有するＳｍ−Ｆｅ−Ｎ系の磁性粒子（異方性Ｓｍ−Ｆｅ−Ｎ系磁性粒子）が好ましい。磁性粒子としてＳｍ−Ｆｅ−Ｎ系磁性粒子を用いれば、当該磁性粒子は磁力が強いので、より磁気特性に優れたものとすることができる。 As the magnetic particles, either an anisotropic one or an isotropic one or both can be used. Anisotropic particles (anisotropic magnetic particles) are preferable from the viewpoint of obtaining stronger magnetic properties. Specifically, Sm-Fe-N-based magnetic particles having anisotropy (anisotropic Sm-Fe-N-based magnetic particles) are preferable. If Sm-Fe-N-based magnetic particles are used as the magnetic particles, the magnetic particles have a strong magnetic force, so that the magnetic particles can be made more excellent in magnetic characteristics.
磁性粒子の平均粒径は、１０μｍ以下が好ましく、１μｍ以上５μｍ以下がより好ましい。１０μｍ以下であれば、製品の表面に凹凸部や亀裂等が発生し難く、外観的に優れたものとすることができ、さらに、低コスト化を図ることができる。平均粒径が１０μｍよりも大きいと、製品の表面に凹凸部や亀裂等が発生して外観的に劣るおそれがある。一方で、平均粒径が１μｍよりも小さいと、磁性粒子のコストが高くなるので、低コスト化の観点から好ましくない。 The average particle size of the magnetic particles is preferably 10 μm or less, more preferably 1 μm or more and 5 μm or less. If it is 10 μm or less, uneven portions and cracks are less likely to occur on the surface of the product, the appearance can be made excellent, and the cost can be further reduced. If the average particle size is larger than 10 μm, uneven portions and cracks may occur on the surface of the product, resulting in inferior appearance. On the other hand, if the average particle size is smaller than 1 μm, the cost of the magnetic particles increases, which is not preferable from the viewpoint of cost reduction.
ボンド磁石用組成物組成物には、更に、流動性を損なうことなく初期強度を向上させるために、ポリスチレン系、ポリオレフィン系、ポリエステル系、ポリウレタン系、ポリアミド系などの熱可塑性エラストマーを配合してもよい。また、円筒状ボンド磁石が高温にさらされた場合にも強度の経時変化を低減できるよう、リン系酸化防止剤などの酸化防止剤を配合してもよい。リン系酸化防止剤としては、トリス（２，４−ジ−ｔｅｒｔ−ブチルフェニル）ホスファイト等が挙げられる。 Even if the composition for the bonded magnet is further blended with a thermoplastic elastomer such as polystyrene, polyolefin, polyester, polyurethane, or polyamide in order to improve the initial strength without impairing the fluidity. Good. Further, an antioxidant such as a phosphorus-based antioxidant may be blended so that the change in strength with time can be reduced even when the cylindrical bond magnet is exposed to a high temperature. Examples of the phosphorus-based antioxidant include tris (2,4-di-tert-butylphenyl) phosphite and the like.
ボンド磁石用組成物中の磁性粒子の含有量は、８０質量％以上９５質量％以下が好ましく、高い磁気特性を得る点から、９０質量％以上９５質量以下がより好ましい。一方、ボンド磁石用組成物中の熱可塑性樹脂の含有量は、３質量％以上２０質量％以下が好ましく、流動性を確保する観点から５質量％以上１５質量％以下がより好ましい。更に熱可塑性エラストマーを含む場合には、熱可塑性樹脂と熱可塑性エラストマーとの質量比率が９０：１０から５０：５０の範囲が好ましく、耐衝撃性の点から９０：１０から７０：３０の範囲がより好ましい。更にリン系酸化防止剤を含む場合には、コンパウンド中のリン系酸化防止剤の含有量は、０．１質量％以上２質量％以下が好ましい。 The content of the magnetic particles in the composition for a bonded magnet is preferably 80% by mass or more and 95% by mass or less, and more preferably 90% by mass or more and 95% by mass or less from the viewpoint of obtaining high magnetic properties. On the other hand, the content of the thermoplastic resin in the composition for a bonded magnet is preferably 3% by mass or more and 20% by mass or less, and more preferably 5% by mass or more and 15% by mass or less from the viewpoint of ensuring fluidity. Further, when the thermoplastic elastomer is contained, the mass ratio of the thermoplastic resin to the thermoplastic elastomer is preferably in the range of 90:10 to 50:50, and in the range of 90:10 to 70:30 from the viewpoint of impact resistance. More preferred. Further, when a phosphorus-based antioxidant is contained, the content of the phosphorus-based antioxidant in the compound is preferably 0.1% by mass or more and 2% by mass or less.
＜＜円筒状ボンド磁石成形用金型＞＞
本発明の一態様にかかる円筒状ボンド磁石成形用金型は、円周方向に磁化された複数の扇形平板磁石を、各扇形平板磁石の磁場方向がそれぞれ円周方向に互いに反発する方向に周方向に配置した配向用磁石、および、円筒状キャビティを有し、該配向用磁石の外周部と円筒状キャビティの内周部の最短ギャップが２ｍｍ以上１０ｍｍ以下であり、円筒状キャビティの外周直径が１００ｍｍ以上３００ｍｍ以下であり、外周半径と内周半径の差が２ｍｍ以上３０ｍｍ以下である。本発明の金型におけるキャビティ、配向用磁石、寸法については前述した。
<< Cylindrical bond magnet molding mold >>
The cylindrical bond magnet molding mold according to one aspect of the present invention surrounds a plurality of fan-shaped flat plate magnets magnetized in the circumferential direction in a direction in which the magnetic field directions of the fan-shaped flat plate magnets repel each other in the circumferential direction. It has an alignment magnet arranged in the direction and a cylindrical cavity, and the shortest gap between the outer peripheral portion of the alignment magnet and the inner peripheral portion of the cylindrical cavity is 2 mm or more and 10 mm or less, and the outer peripheral diameter of the cylindrical cavity is It is 100 mm or more and 300 mm or less, and the difference between the outer peripheral radius and the inner peripheral radius is 2 mm or more and 30 mm or less. The cavity, alignment magnet, and dimensions of the mold of the present invention have been described above.
＜＜円筒状ボンド磁石＞＞
本発明の一態様にかかる円筒状ボンド磁石は、内周側の表面磁束密度が周期的に変動し、該表面磁束密度の正弦波曲線に対する歪率が２２％以下であって、外周直径が１００ｍｍ以上３００ｍｍ以下であり、外周半径と内周半径の差が２ｍｍ以上３０ｍｍ以下である。
<< Cylindrical Bond Magnet >>
In the cylindrical bond magnet according to one aspect of the present invention, the surface magnetic flux density on the inner peripheral side fluctuates periodically, the strain rate of the surface magnetic flux density with respect to the sinusoidal curve is 22% or less, and the outer peripheral diameter is 100 mm. It is 300 mm or less, and the difference between the outer peripheral radius and the inner peripheral radius is 2 mm or more and 30 mm or less.
円筒状ボンド磁石は、上記金型を使用して、ボンド磁石用組成物を射出成型することにより得られる。円筒状ボンド磁石は、内周側の表面磁束密度が周期的に変動し、該表面磁束密度の正弦波曲線に対する歪率が２２％以下であるが、２０％以下が好ましく、１８％以下がより好ましく、１５％以下がさらに好ましく、１０％以下が特に好ましい。表面磁束密度の正弦波曲線に対する歪率が２２％を超えると、円筒状ボンド磁石をモーターに適用した場合にコギングを生じる傾向がある。 The cylindrical bond magnet can be obtained by injection molding a composition for a bond magnet using the above mold. In the cylindrical bond magnet, the surface magnetic flux density on the inner peripheral side fluctuates periodically, and the distortion rate of the surface magnetic flux density with respect to the sinusoidal curve is 22% or less, preferably 20% or less, more preferably 18% or less. It is preferable, 15% or less is more preferable, and 10% or less is particularly preferable. If the distortion factor of the surface magnetic flux density with respect to the sinusoidal curve exceeds 22%, cogging tends to occur when a cylindrical bond magnet is applied to the motor.
円筒状ボンド磁石の高さは５ｍｍ以上１００ｍｍ以下であるが、６ｍｍ以上１５ｍｍ以下が好ましい。５ｍｍ未満では外周方向の磁束密度が小さくなり、１００ｍｍより大きくすると、成形時に部分的に樹脂の冷却スピードにばらつきが生じるため寸法精度が低下することがある。 The height of the cylindrical bond magnet is 5 mm or more and 100 mm or less, but 6 mm or more and 15 mm or less is preferable. If it is less than 5 mm, the magnetic flux density in the outer peripheral direction becomes small, and if it is larger than 100 mm, the cooling speed of the resin partially varies during molding, so that the dimensional accuracy may decrease.
円筒状ボンド磁石は、外周半径に対する外周半径と内周半径の差の比が、円筒状ボンド磁石の強度の点から０．０１以上０．８以下が好ましく、０．０４以上０．６以下がより好ましい。また、円筒状ボンド磁石は、前述した金型を使用して射出成形で得られるため、金型の円筒状キャビティに対応した寸法を有する。円筒状キャビティの寸法については前述した。 For the cylindrical bond magnet, the ratio of the difference between the outer peripheral radius and the inner peripheral radius to the outer peripheral radius is preferably 0.01 or more and 0.8 or less, and 0.04 or more and 0.6 or less from the viewpoint of the strength of the cylindrical bond magnet. More preferred. Further, since the cylindrical bond magnet is obtained by injection molding using the above-mentioned mold, it has a size corresponding to the cylindrical cavity of the mold. The dimensions of the cylindrical cavity have been described above.
円筒状ボンド磁石は、前述したボンド磁石用組成物を射出成形して得られ、熱可塑性樹脂と磁性粒子を含み、さらに熱可塑性エラストマーや酸化防止剤を含み得る。円筒状ボンド磁石中の磁性粒子の含有量は、高い磁気特性を得る点から８０質量％以上９５質量％以下が好ましく、９０質量％以上９５質量％未満がより好ましい。円筒状ボンド磁石中の熱可塑性樹脂の含有量は、流動性を確保する観点から３質量％以上２０質量％以下が好ましく、５質量％以上１５質量％以下がより好ましい。更に熱可塑性エラストマーを含む場合には、円筒状ボンド磁石中の熱可塑性エラストマーの含有量は、熱可塑性樹脂と熱可塑性エラストマーとの質量比率が９０：１０から５０：５０の範囲であることが好ましく、耐衝撃性の点から９０：１０から７０：３０範囲がより好ましい。更に酸化防止剤を含む場合には、円筒状ボンド磁石中の酸化防止剤の含有量は、０．１質量％以上２質量％以下が好ましい。 The cylindrical bond magnet is obtained by injection molding the above-mentioned composition for a bond magnet, contains a thermoplastic resin and magnetic particles, and may further contain a thermoplastic elastomer and an antioxidant. The content of the magnetic particles in the cylindrical bond magnet is preferably 80% by mass or more and 95% by mass or less, and more preferably 90% by mass or more and less than 95% by mass from the viewpoint of obtaining high magnetic properties. The content of the thermoplastic resin in the cylindrical bond magnet is preferably 3% by mass or more and 20% by mass or less, and more preferably 5% by mass or more and 15% by mass or less from the viewpoint of ensuring fluidity. When a thermoplastic elastomer is further contained, the content of the thermoplastic elastomer in the cylindrical bonded magnet is preferably in the range of 90:10 to 50:50 in the mass ratio of the thermoplastic resin and the thermoplastic elastomer. From the viewpoint of impact resistance, the range of 90:10 to 70:30 is more preferable. Further, when an antioxidant is contained, the content of the antioxidant in the cylindrical bond magnet is preferably 0.1% by mass or more and 2% by mass or less.
本発明の一態様にかかる円筒状ボンド磁石は、モーター等の動力装置や、回転センサーなどの信号装置、発電機等の動力装置に用いることができる。 The cylindrical bond magnet according to one aspect of the present invention can be used for a power device such as a motor, a signal device such as a rotation sensor, and a power device such as a generator.
以下、実施例について説明する。なお、特に断りのない限り、「％」は質量基準である。 Hereinafter, examples will be described. Unless otherwise specified, "%" is based on mass.
（１）実施例１
（１−１）ボンド磁石用組成物の製造
サマリウム鉄窒素磁性粉末（平均粒径３μｍ）９０質量％に対して１２ナイロン樹
脂粉末９．５質量％、酸化防止剤粉末０．５質量％をミキサーで混合した
後、混合粉を二軸混練機に投入し、２１０℃にて混練して混練物を得た。得られた混練物
を冷却後、適当な大きさに切断しボンド磁石用組成物を得た。
(1) Example 1
(1-1) Production of Composition for Bond Magnet A mixer of 9.5% by mass of 12 nylon resin powder and 0.5% by mass of antioxidant powder with respect to 90% by mass of samarium iron nitrogen magnetic powder (average particle size 3 μm). After mixing in, the mixed powder was put into a twin-screw kneader and kneaded at 210 ° C. to obtain a kneaded product. The obtained kneaded product was cooled and then cut into an appropriate size to obtain a composition for a bonded magnet.
（１−２）金型および配向用磁石
射出成型用金型および扇形平板磁石の上面からの模式図を図１Ａに示す。金型内に、図１Ａに示すように、配向用磁石と、スリーブを配置し、円筒状キャビティの外周直径２６０ｍｍ、内周直径２５０ｍｍ、厚さ４ｍｍ、高さ１０ｍｍであった。配向用磁石は１２枚の扇形平板磁石より構成されており、扇形平板磁石１枚の辺の長さ１１９ｍｍ、厚さ２０ｍｍ、中心角３０°、表面磁束密度が０．８Ｔのものを用いた。また、図１Ａにおいて、それぞれの扇形平板磁石の矢頭印は磁場方向示しており、磁場方向が隣り合う磁石と円周方向に互いに反発するように配向した扇形平板磁石を用いた。扇形平板磁石から構成される配向用磁石とキャビティとの間には、半径方向の厚さが６ｍｍ（円筒状キャビティの内周部と配向用磁石の外周部との最短ギャップ）のＳＵＳ３０４製の円筒状スリーブを配置した。
(1-2) Mold and Orientation Magnet A schematic view from the upper surface of the injection molding mold and the fan-shaped flat plate magnet is shown in FIG. 1A. As shown in FIG. 1A, an orientation magnet and a sleeve were arranged in the mold, and the outer diameter of the cylindrical cavity was 260 mm, the inner circumference diameter was 250 mm, the thickness was 4 mm, and the height was 10 mm. The alignment magnet was composed of 12 fan-shaped flat plate magnets, and the side length of one fan-shaped flat plate magnet was 119 mm, the thickness was 20 mm, the central angle was 30 °, and the surface magnetic flux density was 0.8 T. Further, in FIG. 1A, the arrowhead marks of the respective fan-shaped flat plate magnets indicate the direction of the magnetic field, and the magnets having the magnetic field directions adjacent to each other and the fan-shaped flat plate magnets oriented so as to repel each other in the circumferential direction were used. A SUS304 cylinder with a radial thickness of 6 mm (the shortest gap between the inner circumference of the cylindrical cavity and the outer circumference of the alignment magnet) between the alignment magnet composed of fan-shaped flat plate magnets and the cavity. A shaped sleeve was placed.
（１−３）射出成形
上記金型を射出成形機に配置した。ボンド磁石用組成物を２４０℃のシリンダー内で溶解させ、９０℃に調温した金型のキャビティ内に射出成形することで、外周直径２６０ｍｍ、内周直径２５０ｍｍ、厚さ４ｍｍ、高さ１０ｍｍの円筒状ボンド磁石を得た。
(1-3) Injection molding The above mold was placed in an injection molding machine. The composition for a bond magnet is melted in a cylinder at 240 ° C. and injection molded into a cavity of a mold whose temperature is adjusted to 90 ° C. to obtain an outer peripheral diameter of 260 mm, an inner peripheral diameter of 250 mm, a thickness of 4 mm, and a height of 10 mm. A cylindrical bond magnet was obtained.
（２）比較例１
実施例１と同じ寸法の円筒状キャビティを有する同じ寸法の金型に対し、表１に示したスリーブの厚みを０．５ｍｍに変更し、表１に示した扇形平板磁石を用いたこと以外は、実施例１と同じ方法で円筒状ボンド磁石を製造した。
(2) Comparative Example 1
For a mold of the same size having a cylindrical cavity of the same size as in Example 1, the thickness of the sleeve shown in Table 1 was changed to 0.5 mm, and the fan-shaped flat plate magnet shown in Table 1 was used. , A cylindrical bond magnet was manufactured by the same method as in Example 1.
（３）比較例２〜４
射出成型用金型および扇形平板磁石の上面からの模式図を図２Ａに示す。実施例１と同じ寸法の円筒状キャビティを有する同じ寸法の金型に対し、表１に示したスリーブの厚みに変更したことと、表１および図２Ａに示した扇形平板磁石を用いたこと以外は、実施例１と同じ方法で円筒状ボンド磁石を製造した。
(3) Comparative Examples 2 to 4
A schematic view from the upper surface of the injection molding die and the fan-shaped flat plate magnet is shown in FIG. 2A. Except for changing the thickness of the sleeve shown in Table 1 to the mold having the same cylindrical cavity having the same size as in Example 1 and using the fan-shaped flat plate magnet shown in Table 1 and FIG. 2A. Manufactured a cylindrical bond magnet in the same manner as in Example 1.
（４）比較例５
射出成型用金型および扇形平板磁石の上面からの模式図を図３Ａに示す。実施例１と同じ寸法の円筒状キャビティを有する同じ寸法の金型に対し、隣り合う扇形平板磁石同士の間に、扇形平板磁石と同じ形状の非磁性スペーサー（ＳＵＳ３０４材）を配置したこと、表１に示したスリーブの厚みに変更したこと、および表１および図３Ａに示した扇形平板磁石を用いたこと以外は、実施例１と同じ方法で円筒状ボンド磁石を製造した。
(4) Comparative Example 5
A schematic view from the upper surface of the injection molding die and the fan-shaped flat plate magnet is shown in FIG. 3A. A non-magnetic spacer (SUS304 material) having the same shape as the fan-shaped flat magnets was placed between adjacent fan-shaped flat magnets for a mold having the same cylindrical cavity with the same dimensions as in Example 1. A cylindrical bond magnet was manufactured in the same manner as in Example 1 except that the thickness of the sleeve shown in 1 was changed and the fan-shaped flat plate magnet shown in Table 1 and FIG. 3A was used.
（５）比較例６
射出成型用金型および扇形平板磁石の上面からの模式図を図４Ａに示す。実施例１と同じ寸法の円筒状キャビティを有する同じ寸法の金型に対し、隣り合う扇形平板磁石同士の間に、扇形平板磁石と同じ形状の磁性材を配置したことと、表１に示したスリーブの厚みに変更したことと、表１および図４Ａに示した扇形平板磁石を用いたこと以外は、実施例１と同じ方法で円筒状ボンド磁石を製造した。なお磁性材はＳＳ４００材であり、飽和磁束密度は２．０Ｔ以上であった。
(5) Comparative Example 6
FIG. 4A shows a schematic view from the upper surface of the injection molding die and the fan-shaped flat plate magnet. Table 1 shows that a magnetic material having the same shape as the fan-shaped flat plate magnets was arranged between adjacent fan-shaped flat plate magnets for a mold having the same size as a cylindrical cavity having the same size as that of the first embodiment. A cylindrical bond magnet was manufactured by the same method as in Example 1 except that the thickness of the sleeve was changed and the fan-shaped flat plate magnet shown in Table 1 and FIG. 4A was used. The magnetic material was SS400, and the saturation magnetic flux density was 2.0 T or more.
（６）比較例７
射出成型用金型および扇形平板磁石の上面からの模式図を図５Ａに示す。実施例１と同じ寸法の円筒状キャビティを有する同じ寸法の金型に対し、表１に示したスリーブの厚みに変更したことと、表１および図５Ａに示した扇形平板磁石を配置したこと以外は、実施例１と同じ方法で円筒状ボンド磁石を製造した。
(6) Comparative Example 7
A schematic view from the upper surface of the injection molding die and the fan-shaped flat plate magnet is shown in FIG. 5A. Except for changing the thickness of the sleeve shown in Table 1 to the mold having the same cylindrical cavity having the same size as in Example 1 and arranging the fan-shaped flat plate magnet shown in Table 1 and FIG. 5A. Manufactured a cylindrical bond magnet in the same manner as in Example 1.
（７）評価
図１Ｂ、図２Ｂ、図３Ｂ、図４Ｂおよび図５Ｂにホール素子で測定した配向用磁石の外周の配向磁場を、図１Ｃ、図２Ｃ、図３Ｃ、図４Ｃおよび図５Ｃに、マグネットアナライザーで測定した円筒状ボンド磁石の内周の表面磁束密度を示す。また、正弦波曲線に対する円筒状ボンド磁石の内周の表面磁束密度の歪み率を表１に示す。歪み率は、波形のひずみの程度を表すもので、フーリエ変換によりその波形に含まれる全高調波成分（Ｅ２〜Ｅｎ）を計算し、その実効値の総和と基本波（Ｅ１）の実効値との比として算出した。
(7) Evaluation The orientation magnetic field of the outer circumference of the alignment magnet measured by the Hall element in FIGS. 1B, 2B, 3B, 4B and 5B is shown in FIGS. 1C, 2C, 3C, 4C and 5C. The surface magnetic flux density of the inner circumference of the cylindrical bond magnet measured by the magnet analyzer is shown. Table 1 shows the distortion rate of the surface magnetic flux density on the inner circumference of the cylindrical bond magnet with respect to the sinusoidal curve. The distortion factor represents the degree of distortion of the waveform. The total harmonic components (E2 to En) contained in the waveform are calculated by Fourier transform, and the sum of the effective values and the effective value of the fundamental wave (E1) are used. It was calculated as the ratio of.
比較例１〜７の円筒状ボンド磁石は、磁極間の表面磁束密度の変化が急峻であり、正弦波曲線に対する歪みが大きかった。また、比較例２〜７では余分な磁極が生じた。これに対し、実施例１の円筒状ボンド磁石は、スリーブ厚さを調節し、隣り合う扇形平板磁石を、磁場方向がそれぞれ円周方向に互いに反発する方向に配置して磁場配向させたため、比較例１〜７と同じ形状であるにもかかわらず正弦波曲線に対する歪みが低減された。 In the cylindrical bond magnets of Comparative Examples 1 to 7, the change in the surface magnetic flux density between the magnetic poles was steep, and the distortion with respect to the sinusoidal curve was large. Further, in Comparative Examples 2 to 7, extra magnetic poles were generated. On the other hand, in the cylindrical bond magnet of Example 1, the sleeve thickness was adjusted, and adjacent fan-shaped flat plate magnets were arranged in directions in which the magnetic field directions repel each other in the circumferential direction, so that the magnetic field was oriented. Although the shape is the same as in Examples 1 to 7, the distortion for the sinusoidal curve is reduced.
本発明の異方性磁性粉末の円筒状ボンド磁石の製造方法は、正弦波曲線またはそれに近似した表面磁束密度を有する大径の円筒状ボンド磁石を製造できる。この円筒状ボンド磁石を大型モーターに適用した場合、コギングを抑制できる。 The method for producing an anisotropic magnetic powder cylindrical bond magnet of the present invention can produce a large-diameter cylindrical bond magnet having a sinusoidal curve or a surface magnetic flux density close thereto. When this cylindrical bond magnet is applied to a large motor, cogging can be suppressed.
１：配向用磁石
２：キャビティ
３：鋼材
４：スリーブ
1: Orientation magnet 2: Cavity 3: Steel material 4: Sleeve
Claims (9)
前記金型にボンド磁石用組成物を注入して射出成形する工程とを含む、円筒状ボンド磁石の製造方法であって、
前記円筒状キャビティの内周部と前記配向用磁石の外周部との最短ギャップが２ｍｍ以上１０ｍｍ以下であり、
前記円筒状キャビティは、外周直径が１００ｍｍ以上３００ｍｍ以下であって、外周半径と内周半径の差が２ｍｍ以上３０ｍｍ以下であって、
前記配向用磁石は、円周方向に磁化された複数の扇形平板磁石から構成され、扇形平板磁石は、隣り合う扇形平板磁石の磁場方向がそれぞれ円周方向に互いに反発するように円周方向に配置された、
円筒状ボンド磁石の製造方法。 A process of arranging a mold having a cylindrical cavity and an alignment magnet in an injection molding machine,
A method for manufacturing a cylindrical bond magnet, which comprises a step of injecting a composition for a bond magnet into the mold and injection molding.
The shortest gap between the inner peripheral portion of the cylindrical cavity and the outer peripheral portion of the alignment magnet is 2 mm or more and 10 mm or less.
The cylindrical cavity has an outer peripheral diameter of 100 mm or more and 300 mm or less, and a difference between the outer peripheral radius and the inner peripheral radius of 2 mm or more and 30 mm or less.
The alignment magnet is composed of a plurality of fan-shaped flat plate magnets magnetized in the circumferential direction, and the fan-shaped flat plate magnets are arranged in the circumferential direction so that the magnetic field directions of adjacent fan-shaped flat plate magnets repel each other in the circumferential direction. Placed,
A method for manufacturing a cylindrical bond magnet.
該配向用磁石の外周部と円筒状キャビティの内周部の最短ギャップが２ｍｍ以上１０ｍｍ以下であり、円筒状キャビティの外周直径が１００ｍｍ以上３００ｍｍ以下であり、外周半径と内周半径の差が２ｍｍ以上３０ｍｍ以下である円筒状ボンド磁石成形用金型。 It has an alignment magnet in which a plurality of fan-shaped flat plate magnets magnetized in the circumferential direction are arranged in the circumferential direction in which the magnetic field directions of the fan-shaped flat plate magnets repel each other in the circumferential direction, and a cylindrical cavity.
The shortest gap between the outer peripheral portion of the alignment magnet and the inner peripheral portion of the cylindrical cavity is 2 mm or more and 10 mm or less, the outer peripheral diameter of the cylindrical cavity is 100 mm or more and 300 mm or less, and the difference between the outer peripheral radius and the inner peripheral radius is 2 mm. A mold for forming a cylindrical bond magnet having a diameter of 30 mm or more.
The cylindrical bond magnet according to claim 8, wherein the ratio of the difference between the outer peripheral radius and the inner peripheral radius to the outer peripheral radius is 0.01 or more and 0.8 or less.
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