DE102014105172B4 - PROCESS FOR THE SIMULTANEOUS MANUFACTURE OF AT LEAST TWO PERMANENT MAGNETS - Google Patents

Abstract

A method for producing at least two pressed permanent magnets from a magnet powder (200), comprising the steps of: providing a press (100) having a die (130) with a first press cavity (150) and a second press cavity (150'), and one first press ram (110) and a second press ram (110'), each of which can be adjusted in a pressing direction (z) relative to the die (130); providing a magnetic powder (200); providing a coil arrangement (161, 162); filling in the Magnetic powder (200) into the first pressing cavity (150) and into the second pressing cavity (150') with the aid of a filling magnetic field which is generated with the coil arrangement (161, 162) while the coil arrangement (161, 162) is relative to the die ( 130) is in a first relative position;aligning the magnetic orientation of the magnetic powder (200) filled into the press cavity (150, 150') with the aid of an orientation magnetic field (HOM) which is generated with the coil arrangement (161, 162) while the coil arrangement (161, 162) is in a second relative position, which is different from the first relative position, with respect to the die (130); simultaneous pressing of the magnetic powder (200) filled into the pressing cavity (150, 150') and aligned with the aid of the orientation magnetic field (HOM), in that a part of the magnet powder (200) located in the first press cavity (150) is compressed by the action of the first press die (110) to produce a first green body and the first green body is sintered to form a first powder-pressed permanent magnet; and- a part of the magnet powder (200) located in the second press cavity (150') is compressed by the action of the second press die (110) to produce a second green body and the second green body is sintered to form a second powder-pressed permanent magnet.

Description

Permanent magnets are used in a wide variety of technical fields. It is often important that the permanent magnets generate a magnetic field with a high magnetic flux density. Just one example of this is a magnetic flux within an air gap, which z. B. between two poles of the same or different permanent magnet (s) or between one pole of a permanent magnet and an iron yoke is formed. Examples of such applications are motors or generators. For example, permanent magnets are often used in the rotors of motors or generators. Permanent magnets with a high magnetic flux density are also advantageous in many other technical fields, such as magnet systems for magnetocalorics. However, conventional magnet arrangements with which high flux densities can be generated are complex and therefore expensive to manufacture.

The publication DE 102 46 719 A1 discloses a method of making multi-pole ring magnets having two or multiples of oppositely oriented magnetic poles in their outer ring peripheral region. A powder made of a magnetically orientable material is pressed into a ring shape in a press cavity of a die and two or more poles are magnetically oriented in the process. The powder is sucked into the press cavity by means of a magnetic field.

The publication DE 10 2004 008 322 B4 discloses a powder press for producing compacts from powder-form pressing material, having: a die plate with at least two dies or a die with two die bores; at least two upper punches which interact with the dies or the die bores; a hydraulic drive for the punches; at least two lower punches which interact with the dies or die bores; and a hydraulic drive for the lower punches. Separate hydraulic cylinders for the lower punches are provided. At least one position sensor is assigned to the upper punches and one position sensor to each of the lower punches. At least one force sensor for the upper punch and one force sensor for each of the lower punches are provided, and each hydraulic cylinder for the lower punch is assigned a controller that is connected to the associated position sensor and the associated force sensor.

The publication DE 20 2010 010 105 U1 discloses a permanent magnetization system for generating a directed permanent magnetic field with a high field strength in a magnetization space, the permanent magnetization system essentially consisting of an outer, closed permanent magnet system and an inner permanent magnet system, the permanent magnet systems consisting of a large number of individual magnets or magnet segments.

The publication DE 10 356 964 A1 discloses a method for producing a plastic-bonded magnet with a magnetic metal powder, which is anisotropic in terms of its magnetic properties, and a plastic component. The magnetic metal powder is mixed with the plastic component to form a mixed material and filled into a mold. Magnetic orientation is performed in an orientation field. The mixed material is pressed, hardened and designed so that the plastic component contains a duromer that is liquid at room temperature.

The object of the present invention is, inter alia, to provide a method for producing a plurality of pressed permanent magnets.

These objects are achieved by a method for the simultaneous production of at least two pressed permanent magnets according to claim 1. Further developments of the invention are the subject matter of subclaims

A method for the simultaneous production of at least two permanent magnets, each pressed from a magnetic powder, is described. For this purpose, a press is provided which has a die with a first press cavity and a second press cavity. Also provided are a first ram and a second ram, each adjustable in a pressing direction relative to the die, magnetic powder, and a coil assembly. While the coil arrangement is in a first relative position with respect to the die, the magnetic powder is filled into the first press cavity and into the second press cavity with the aid of a filling magnetic field that is generated with the coil assembly. While the coil arrangement is in a second relative position with respect to the die, which differs from the first relative position, the magnetic orientation of the magnetic powder filled into the first press cavity and into the second press cavity is aligned with the aid of an orientation magnetic field, which is also generated with the coil assembly. The magnetic powder filled into the first press cavity and into the second press cavity and aligned with the aid of the orientation magnetic field is simultaneously pressed, in that a part of the magnetic powder located in the first press cavity is compressed by the action of the first press ram, resulting in a first green body and the first green body becomes one sintering a first powder-pressed permanent magnet, and by compressing a part of the magnet powder in the second pressing cavity by the action of the second die to give a second green body, and sintering the second green body into a second powder-pressed permanent magnet.

• 1 einen Motor, der einen mit Permanentmagneten bestückten Rotor aufweist.
• 2A und 2B Permanentmagnete mit starkem Nord-Süd-Effekt.
• 2C die Ansicht des Magneten gemäß 2A mit mehreren zur magnetischen Orientierungsachse senkrechten, äquidistanten Schnittebenen.
• 2D die Ansicht des Magneten gemäß 2B mit mehreren zur magnetischen Orientierungsachse senkrechten, äquidistanten Schnittebenen.
• 2E eine perspektivische Ansicht eines Permanentmagneten, der auf eine Projektionsebene projiziert wird.
• 2F eine Draufsicht auf die in 2E dargestellte Projektionsebene.
• 3A einen Vertikalschnitt durch eine Presse zur Herstellung eines aus einem Magnetpulver gepressten Magneten, während des Pressvorgangs.
• 3B eine vergrößerte Darstellung des in der Presse gemäß 3A verpressten Magnetpulvers.
• 4A eine Ansicht der Pressfläche des Unterstempels der Presse gemäß 3A.
• 4B eine Ansicht der Pressfläche des Oberstempels der Presse gemäß 3A.
• 5A bis 5F Vertikalschnitte durch verschiedene Ausgestaltungen von Unterstempeln, wie sie bei einer Presse zur Herstellung von Magneten mit starkem Nord-Süd-Effekt eingesetzt werden können.
• 6A und 6B Horizontalschnitte durch verschiedene Ausgestaltungen von Unterstempeln, wie sie bei einer Presse zur Herstellung von Magneten mit starkem Nord-Süd-Effekt eingesetzt werden können.
• 7A und 7B mögliche Horizontalschnitte durch weitere verschiedene Ausgestaltungen von Unterstempeln, wie sie bei einer Presse zur Herstellung von Magneten mit starkem Nord-Süd-Effekt eingesetzt werden können.
• 8A bis 8C schematische Darstellungen der Verläufe des magnetischen Flusses bei der Verwendung von Oberstempeln, die aus verschiedenen zusammengesetzt sind.
• 9A und 9B eine weitere Presse zur Herstellung pulver-gepresster Permanentmagnete.
• 10A bis 10C noch eine andere Presse zur Herstellung pulver-gepresster Permanentmagnete, mittels der sich ein pulver-gepresster Permanentmagnet mit starkem Nord-Süd-Effekt unter Verwendung von mehreren Spulen erzeugen lässt.
• 11A bis 11D eine Presse zur Herstellung pulver-gepresster Permanentmagnete, mittels der während eines Pressvorgangs zwei Permanentmagnete simultan gepresst werden können.
• 12 eine Presse zum simultanen Pressen von vier hinsichtlich ihrer geometrischen Form und ihrer Verteilung des Magnetfeldes identischen Magneten.
• 13A das Befüllen von zwei Presshohls mit einem Magnetpulver.
• 13B das Orientieren des Magnetpulvers nach einer Änderung der Relativposition zwischen der Magnetspule und den Presshohls.
• 14 ein Verfahren entsprechend den 13A und 13B, mit dem Permanentmagnete hergestellt werden, die ein im Wesentlichen homogenes Magnetfeld aufweisen.
• 15A ein Verfahren entsprechend den 13A und 13B, mit dem Permanentmagnete hergestellt werden, die ein stark inhomogenes Magnetfeld aufweisen.
• 15B ein Verfahren entsprechend den 13A und 13B, mit dem Permanentmagnete hergestellt werden, die ein stark inhomogenes Magnetfeld aufweisen.
• 15C einen gemäß dem Verfahren nach 15A hergestellten Permanentmagneten.
• 15D einen gemäß dem Verfahren nach 15B hergestellten Permanentmagneten.
• 15E eine Draufsicht auf die Einfüllöffnung eines Presshohls.
• 16 einen Einfülltrichter zum Einfüllen eines Magnetpulvers in ein breites Presshohl.
• 17 einen Einfülltrichter zum Einfüllen eines Magnetpulvers in ein schmales Presshohl.
• 18 einen Einfülltrichter zum Einfüllen eines Magnetpulvers in zwei benachbarte, breite Presshohls.
• 19 einen Einfülltrichter zum Einfüllen eines Magnetpulvers in zwei benachbarte, schmale Presshohls.
• 20 ein Beispiel zur Veranschaulichung der Begriffe „Pressen im Axialfeld“, und „Pressen im Querfeld“.
• 21 einen Motor, der einen mit Permanentmagneten bestückten Rotor aufweist, wobei ein jeder der Magnete eine betragsmäßig hohe magnetische Winkelstreuung und/oder einen betragsmäßig großen Nord-Süd-Effekt aufweist.
• 22A bis 22C Anordnungen mit zwei Permanentmagneten, deren Magnetisierungsrichtungen sich nordpolseitig der beiden Magnete schneiden.
• 23A bis 23C Anordnungen mit zwei Permanentmagneten, deren Magnetisierungsrichtungen sich südpolseitig der beiden Magnete schneiden.
• 24 einen Motor, der einen mit Permanentmagneten bestückten Rotor aufweist, entlang dessen Umfang Nordpole und Südpole abwechselnd aufeinander folgen, wobei jeder der Nordpole durch zwei Magneten gebildet wird.

The invention is explained in more detail below using exemplary embodiments with reference to the attached figures. In the figures, the same reference symbols designate the same or corresponding elements. Show it:

• 1 a motor having a rotor fitted with permanent magnets.
• 2A and 2 B Permanent magnets with a strong north-south effect.
• 2C according to the view of the magnet 2A with several equidistant sectional planes perpendicular to the magnetic orientation axis.
• 2D according to the view of the magnet 2 B with several equidistant sectional planes perpendicular to the magnetic orientation axis.
• 2E a perspective view of a permanent magnet projected onto a projection plane.
• 2F a top view of the in 2E shown projection plane.
• 3A a vertical section through a press for the production of a magnet pressed from a magnetic powder during the pressing process.
• 3B according to an enlarged view of the in the press 3A compressed magnetic powder.
• 4A a view of the pressing surface of the lower ram of the press according to FIG 3A .
• 4B a view of the pressing surface of the upper punch of the press according to FIG 3A .
• 5A until 5F Vertical sections through various configurations of lower punches, as can be used in a press to produce magnets with a strong north-south effect.
• 6A and 6B Horizontal sections through various configurations of lower punches, as can be used in a press to produce magnets with a strong north-south effect.
• 7A and 7B possible horizontal sections through other different designs of lower punches, as can be used in a press for the production of magnets with a strong north-south effect.
• 8A until 8C Schematic representations of the course of the magnetic flux when using upper punches that are composed of different ones.
• 9A and 9B another press for the production of powder-pressed permanent magnets.
• 10A until 10C yet another press for producing powder-pressed permanent magnets, by means of which a powder-pressed permanent magnet with a strong north-south effect can be produced using several coils.
• 11A until 11D a press for the production of powder-pressed permanent magnets, by means of which two permanent magnets can be pressed simultaneously during a pressing process.
• 12 a press for simultaneously pressing four magnets that are identical in terms of their geometric shape and their distribution of the magnetic field.
• 13A the filling of two press hollows with a magnetic powder.
• 13B orienting the magnetic powder after a change in the relative position between the magnetic coil and the dies.
• 14 a procedure according to 13A and 13B , with which permanent magnets are produced that have a substantially homogeneous magnetic field.
• 15A a procedure according to 13A and 13B , which is used to produce permanent magnets that have a highly inhomogeneous magnetic field.
• 15B a procedure according to 13A and 13B , which is used to produce permanent magnets that have a highly inhomogeneous magnetic field.
• 15C one according to the procedure 15A manufactured permanent magnets.
• 15D one according to the procedure 15B manufactured permanent magnets.
• 15E a plan view of the filling opening of a press cavity.
• 16 a hopper for filling a magnetic powder into a wide die cavity.
• 17 a hopper for filling a magnetic powder into a narrow press cavity.
• 18 a hopper for filling a magnetic powder into two adjacent wide die cavities.
• 19 a hopper for filling a magnetic powder into two adjacent narrow press cavities.
• 20 an example to illustrate the terms "pressing in the axial field" and "pressing in the transverse field".
• 21 a motor that has a rotor equipped with permanent magnets, each of the magnets having a high magnetic angular spread and/or a high north-south effect in terms of absolute value.
• 22A until 22C Arrangements with two permanent magnets whose directions of magnetization intersect on the north pole side of the two magnets.
• 23A until 23C Arrangements with two permanent magnets whose directions of magnetization intersect on the south pole side of the two magnets.
• 24 a motor having a rotor fitted with permanent magnets, along the circumference of which north poles and south poles follow one another alternately, each of the north poles being formed by two magnets.

MAGNETS WITH HIGH MAGNETIC ANGULAR SPREAD

1 shows a schematic representation of a motor with a rotor 1 and a stator 2, between which there is an air gap 12. The rotor 1 has an axis 15 about which it is rotatable relative to the stator. Permanent magnets 10, 20 are arranged along the circumference of the rotor 1. The orientation of the permanent magnets 10 is selected such that the north poles N are directed outwards in the radial direction of the rotor 1 , while the south poles S face the axis 15 of the rotor 1 . The permanent magnets 20 , on the other hand, have an oppositely directed magnetization, ie the south poles S are directed outwards in the radial direction of the rotor 1 , while the north poles N face the axis 15 of the rotor 1 . The permanent magnets 10 and the permanent magnets 20 are thus arranged along the circumference of the rotor 1 such that a north pole N always follows a south pole S and a south pole S is followed by a north pole N along the circumference. In 1 as in some other figures, the orientations of the magnetic orientation axes M0 of the permanent magnets 10, 20, which are still to be explained, and the orientation of the local magnetization at individual points of the permanent magnets 10, 20 are indicated schematically by stylized compass needles, the tips of which point in the direction of the north pole N. The opposite ends of the compass needles point in the direction of the south pole S. Not shown in 1 are the electrical magnetic coils present in the stator 2.

According to one aspect of the invention, it has proven advantageous to use permanent magnets 10, 20 in order to generate high magnetic flux densities in an air gap, for example the above-mentioned air gap 12, in which the local magnetization directions present within the permanent magnet 10, 20 are distributed in a highly inhomogeneous manner are. This inhomogeneous distribution is chosen so that with a single permanent magnet 10, 20, d. H. a permanent magnet 10, 20, which is not in an environment that affects the course of its magnetic field, the flux density measured on it at a first point, which is on the side of the magnet that faces the air gap when the permanent magnet 10, 20 is installed is greater than at a second point opposite the first point, which is located on the side of the magnet that faces away from the air gap in the installed state.

The inhomogeneity of such a highly inhomogeneous distribution of the local magnetization directions within a permanent magnet 10, 20 can be described by the angular deviations of the local magnetization directions from the direction of the magnetic orientation axis M0 of the permanent magnet 10, 20 in question, which is explained below with reference to 2A until 2D is explained. As a measure of the inhomogeneity of the distribution of the local directions of magnetization within the permanent magnet 10, 20, a “magnetic angle spread” of a permanent magnet 10, 20 is introduced below. It gives a measure of how strongly the local magnetization directions scatter in a permanent magnet.

The 2A until 2D show sectional views of permanent magnets 10 and 20, as they are for example in a motor 1 excited by permanent magnets 10, 20 according to FIG 1 can be used. The permanent magnets 10, 20 each have a magnetic orientation axis M0 represented by an arrow.

For the purposes of the present invention, the direction of the magnetic orientation axis M0 of a permanent magnet 10, 20 is defined as follows: If the permanent magnet 10, 20 is placed in a homogeneous magnetic field, the permanent magnet 10, 20 aligns itself provided no other forces are acting on it as the magnetic forces resulting from the homogeneous magnetic field in which homogeneous magnetic field in such a way that the magnetic orientation axis M0 runs parallel to the homogeneous magnetic field. The magnetic orientation axis M0 also runs through the center of gravity SP of the permanent magnet 10, 20. The alignment of the magnetic orientation axis M0 is therefore linked to the alignment of the magnet 10, 20, ie the magnetic orientation axis M0 is fixed relative to the permanent magnet 10, 20.

In the aforementioned sense, a permanent magnet is in a "homogeneous" magnetic field if, after being introduced into the magnetic field and up to its spatial alignment caused solely by the magnetic field, the permanent magnet is located exclusively in a spatial area in which the magnetic field is present at every point constantly has the same direction and strength. Such a homogeneous magnetic field can be generated in a known manner to a good approximation, for example by means of a pair of Helmholtz coils.

Like the 2A and 2 B As can be seen, a permanent magnet 10, 20 has a local direction of magnetization at each point S1, S2 of its volume region, which is represented by a stylized compass needle filled with white, and which corresponds to the direction of the local magnetic orientation axis m1, m2 of the permanent magnet 10, 20 at the associated point S1, S2. A local direction of magnetization present at a point S1, S2 of a permanent magnet 10, 20 can in principle be oriented in any way relative to the permanent magnet 10, 20 and thus also relative to its magnetic orientation axis M0.

At each point R of the permanent magnet 10, 20, the local magnetic orientation direction m1, m2 present there has a local angle deviation Φ _lok (R) from the direction of the magnetic orientation axis M0 of the entire permanent magnet 10, 20 that is dependent on this point R. In 2A the local angular deviations Φ _lok (S1) and Φ _lok (S2) are shown as examples for the points R = S1 and R = S2.

An "angular spread" D _PM of a permanent magnet 10, 20 within the meaning of the present invention is specified in relation to the direction of a straight line G, which intersects the magnetic orientation axis M0 of the entire permanent magnet 10, 20 at a right angle so that the direction of the straight line G through a rotation of 90° in the mathematically positive sense (left rotation) in the direction of the magnetic orientation axis M0. 2C again shows the permanent magnet 10 according to FIG 2A in the same sectional view, but enlarged. Correspondingly shows 2D an enlarged view of the permanent magnet 20 according to FIG 2 B in the same sectional view. The permanent magnet 10 extends over a length L in the direction of the straight line G.

In the 2C and 2D several mutually parallel sectional planes E are shown, which run perpendicular to the straight line G and parallel to the magnetic orientation axis M0 and intersect the permanent magnet 10, 20 in question. As a result, the relevant permanent magnet 10, 20 is virtually divided into an even number n≧2 partial magnets 10i or _20i (i=1 . . . n), which have identical thicknesses D in the direction of the straight line G. In order to determine the angular dispersion D _PM of a real magnet, this or an identical reference magnet can be divided along the sectional plane E, so that the partial magnets 10 _i and 20 _i are present as individual partial magnets that are separate from one another. The sectional planes E basically run parallel to one another. One (E0) of the sectional planes E runs in such a way that it separates two half-spaces from one another: A positive half-space HR ⁺ , which extends from the sectional plane E0 in the direction of the straight line G and which contains one half of the partial magnets 10 _i and 20 _i (i = 1 . . . n/2) and a negative half-space HR ^- which, starting from the sectional plane E0, extends counter to the direction of the straight line G and which contains the other half of the partial magnets 10 _i and 20 _i (i=n/ 2+1 ... n). The number of partial magnets 10 _i and 20 _i that are located in the negative half-space HR ^- is therefore identical to the number of partial magnets 10 _i and 20 _i that are located in the positive half-space HR ⁺ .

In the example shown, one (E0) of the sectional planes E runs through the center of gravity SP of the magnet 10, 20, which, however, does not necessarily have to be the case with magnets of basically any shape.

Each of the partial magnets 10 _i and 20 _i has _a magnetic orientation axis M _i (i=1 10 _i or 20 _i is directed. These magnetic orientation axes M _i and the associated magnetic orientation directions can be used for the respective sub-magnets 10 _i and 20 _i in the same way, e.g. B. by their orientation in a homogeneous magnetic field, which can be generated for example by a pair of Helmholtz coils, are determined as the magnetic orientation axis M0 for the entire permanent magnet 10, 20. In the 2C and 2D For each of the partial magnets 10i and _20i, the magnetic orientation axis M _i of the relevant partial magnet _10i and _20i is shown, as well as that from south to north pointing direction r _M0 of the magnetic orientation axis M0 of the entire permanent magnet 10 or 20. Also shown is the angle Φ _i (i=1...n) between the magnetic orientation axis M0 and the projection J _i of the magnetic orientation axis M _i of the relevant Partial magnets 10 _i and 20 _i onto a projection plane which is spanned by the magnetic orientation axis M0 and the straight line G. This projection plane is thus identical to the plane of representation 2C or. 2D . It should be noted that the angles Φ _i (i = 1... n) are to be related to the relative orientation of the partial magnets 10 _i and 20 _i (i = 1... n), which the partial magnets 10 _i and 20 _i (i = 1 . . . n) in the composite of the undivided permanent magnets 10 and 20 respectively.

Each of the angles Φ _i (i = 1 ... n) is in the projection plane, starting from the direction r _M0 of the magnetic orientation axis M0, in the mathematically positive sense of rotation (ie turning to the left) in an angular range from 0° to exclusively 180° or im mathematically negative direction of rotation (ie turning to the right) in an angular range of exclusively 0° up to and including -180°, where the angle Φ _i has a positive sign for a rotation in the mathematically positive sense and a negative sign for a rotation in the mathematically negative sense . The directions of the magnetic orientation axes M0 and M _i (i=1 . . . n) are each directed from south to north. If the magnetic orientation axis M0 of the entire magnet 10 or 20 is rotated by an angle Φ _i belonging to one of the partial magnets 10 _i or 20 _i , its direction (after the rotation) is identical to the direction of the orthogonal projection J _i of the associated magnet Orientation axis M _i of the relevant partial magnet 10 _i or 20 _i on the projection plane. In 2C for example, the angles Φ ₁ and Φ ₂ are negative, the angles Φ _n-1 and Φ _n are positive, in 2D on the other hand, the angles Φ ₁ and Φ ₂ are positive and the angles Φ _n-1 and Φ _n are negative.

In terms of the present invention, the angular dispersion D _PM of a permanent magnet 10 or 20 divided into individual sub-magnets 10 _i=1...n or 20 _i=i...n is as follows: $$D_{PM}=\frac{4}{n}\cdot {\displaystyle \sum _{i=1}^n{\mathrm{\Phi }}_i}\cdot siGn\left(G_i-G_0\right)$$

In this case, Φ _i (i=1 . . . n) corresponds to that already referred to in FIG 2C and 2D explained angle between the magnetic orientation axis M0 and the projection J _i of the magnetic orientation axis M _i of the relevant partial magnet 10 _i or 20 _i on a projection plane which is spanned by the magnetic orientation axis M0 and the straight line G.

The function sign(g _i - g ₀ ) is a sign function. It assumes the value '+1' when the associated partial magnet 10 _i or 20 _i is in the positive half-space HR ⁺ , and the value '-1' when the associated partial magnet 10 _i or 20 _i is in the negative half-space HR ^- located. Here, g _i stands for the position of the center of gravity of the relevant partial magnet 10 _i or 20 _i on the straight line G and g ₀ for the position of the center of gravity SP on the straight line G.

The (even) number n of the partial magnets 10 _i or 20 _i can in principle be selected as desired. Preferably n is ≥ 10 or even ≥ 20.

As already explained, the direction of the straight line G is chosen so that it is mapped onto the magnetic orientation axis M0 in the case of a rotation that takes place in the projection plane by an angle of rotation of 90° in the mathematically positive direction of rotation around its point of intersection with the magnetic orientation axis M0. The direction of the magnetic orientation axis M0 and the direction of the straight line G are therefore identical after the rotation. L = n * D applies. In the previous definition, the values of the coordinates on the straight line G increase in the direction of the straight line G. The coordinate of the point G2 is therefore larger than the coordinate of the point G1, and also larger than the coordinate of the center of gravity SP. In addition, the coordinate of the center of gravity SP is larger than the coordinate of the point G1.

The value of the magnetic angular spread D _PM generally assumes different values along different straight lines G, each running perpendicular to the magnetic orientation axis M0. For example, a cuboid magnet 10, 20, whose magnetic orientation axis M0 runs parallel to its thickness direction (i.e. in the direction of the or one of the shortest edge lengths of the cuboid), can have an angular spread D _PM1 in the direction of a first straight line g1, the absolute value of which is greater than 20 ° or greater than 30°, while along a second straight line g2, which is perpendicular both to g1 and to the magnetic orientation axis M0, it can have an angular spread D _PM2 , the magnitude of which is very much less than 20°, for example less than 1° .

An alternative way of specifying the inhomogeneous distribution of the magnetic field of a permanent magnet with a simple number or of determining it in a simple way is the so-called "north-south effect". The use of the north-south effect is suitable for magnets that have the geometry of a right prism with plane-parallel pole faces (including the "rectangular" limiting case). The two flat sides facing away from each other are used as pole faces Designates prisms, each having an intersection with the magnetic orientation axis M0. The north-south effect is discussed below with renewed reference to the 2A and 2 B explained.

To determine the strength of the north-south effect, two points P1 and P2 are first determined on the magnetic orientation axis M0 of the relevant permanent magnet 10, 20. In the case of the permanent magnets 10, 20, the point P1 is in each case on the north pole side and the point P2 is in each case on the south pole side. The points P1, P2 have the same distance d0 from the permanent magnet 10, 20 in question along the magnetic orientation axis M0, which is also referred to below as the measuring distance d0. How based on 2E and 2F is explained using the example of a permanent magnet 10, a minimum width of the orthogonal projection F _P can be determined from the orthogonal projection F P of the permanent magnet 10 onto a projection plane _Ep perpendicular to the magnetic orientation axis M0. For this purpose, the (generally different) widths B10 of the orthogonal projection F _P are to be determined in each case along straight lines b which lie in the projection plane E _P and which intersect the magnetic orientation axis M0. The minimum width B10 _min thus corresponds to the smallest of all possible widths B10. 2E shows a perspective view of the permanent magnet 10 and the projection plane E _P with the orthogonal projection Fp of the permanent magnet 10, and 2F a plan view of the projection plane E _P with the orthogonal projection F _P . The measuring distance d0 is now selected so that it is at least as large as the minimum width B10 _min . For example, the measuring distance d0 can be chosen so that it is equal to B10 _min , or so that it is at least 1.5 times B10 _min .

The absolute amounts B1 and B2 can now be determined at the points P1, P2, which have the magnetic flux density of the field emanating from the magnets 10 and 20 in air in the direction of the magnetic orientation axis M0. The values of B1 and B2 must be measured at the same temperature, e.g. B. at room temperature (20°C). The greater the difference between amounts B1 and B2, the more pronounced the north-south effect. The following value serves as a measure of the strength of the north-south effect: $${\text{W}}_{\text{NS}}=2\cdot \left(\text{<figure-callout id="1" label="B" filenames="DE102014105172B4\_0027.png,DE102014105172B4\_0028.png" state="{{state}}">B</figure-callout>}1-\text{B}2\right)/\left(\text{<figure-callout id="1" label="B" filenames="DE102014105172B4\_0027.png,DE102014105172B4\_0028.png" state="{{state}}">B</figure-callout>}1+\text{B}2\right)$$

If B1 is greater than B2, the north side N of the permanent magnet 10 or 20 is called the "hot side", the opposite south side S is called the "cold side". Otherwise, if B2 is greater than B1, the south side S of the permanent magnet 10 or 20 is called the "hot side", and the opposite north side N is called the "cold side". The north-south effect is more pronounced the larger the absolute value of W _NS is. If W _NS (not the absolute value of W _NS ) is greater than zero, then the hot side is on the north side N and the cold side is on the south side S of magnet 10, which is in 2A is shown. Conversely, if W _NS is less than zero, then the hot side is on the south side S and the cold side is on the north side N of magnet 20, resulting in 2 B is shown. Prerequisite for the emergence of an N/S effect in magnets, which have the geometry of a right prism with plane-parallel pole faces, are local deviations of the magnetic orientation direction from the magnetic orientation axis M0.

Permanent magnets 10, 20, in which the absolute value of the angular spread D _PM and/or the absolute value of the measure W _NS for the strength of the north-south effect is significantly higher than with conventional values, can be, for example, using one of the following manufacture explained procedures.

For example, with such a permanent magnet 10, 20, which has plane-parallel pole faces and can also optionally have the shape of a right prism, the absolute value of W _NS at the measuring distance d0 can be at least 0.18 (e.g. less than or equal to -0 .18 or greater than or equal to +0.18), or at least 0.25 (e.g. less than or equal to -0.25 or greater than or equal to +0.25), or at least 0.30 (e.g .less than or equal to -0.30 or greater than or equal to +0.30). The measurement distance d0 can be at least B10 _min , for example, or even at least 1.5-B10 _min .

Alternatively or additionally, the permanent magnet 10, 20 can have an angular spread D _PM whose absolute value |D _PM | for example is greater than 20° (e.g. less than -20° or greater than +20°), or even greater than 30° (e.g. less than -30° or greater than +30°). The shape of the permanent magnet 10, 20 is basically arbitrary. For example, it can be cuboid or essentially cuboid. All of the values given relate to a temperature of 20°C.

MANUFACTURE OF MAGNETS WITH HIGH MAGNETIC ANGULAR SPREAD

The production of a permanent magnet, which has a high magnetic angular spread D _PM and/or a pronounced north-south effect, can be achieved by pressing a magnetic or magnetizable powder (hereinafter (also referred to as "magnetic powder"), the powder particles of which have been magnetically aligned in a highly inhomogeneous magnetic field. Several examples are explained below.

3A shows an exemplary structure of a press 100, with which powder-pressed permanent magnets can be produced with a large magnetic angular spread in terms of amount or with a strong north-south effect in terms of amount, in vertical section. The press 100 comprises a die 130 with a cavity 150, which serves to receive a magnet powder 200 to be pressed into a magnet. The cavity 150 is also referred to as a "press cavity".

A lower punch 110 and/or an upper punch 120 are used to press a powder 200 filled into the press cavity 150 . During the pressing process, the lower punch 110 and/or the upper punch 120 are moved parallel to the pressing direction relative to the die 130 with simultaneous compression of the powder 200, which is shown in 3A is indicated by corresponding arrows. Optionally, the lower punch 110 or the upper punch 120 can be stationary relative to the die 130 while the other punch 120 or 110 is moved relative to the die 130 for compressing the powder 200 . The pressing of the magnetic powder 200 results in a single magnetic body that can be used, for example, as a permanent magnet 10 or 20, as described above.

The individual particles of the magnetic powder 200 each have a preferred magnetic direction, the alignment of which is fixed by pressing the magnetic powder 200 relative to the magnetic body produced. However, the pressing process results in a compaction of the magnetic powder 200 and, as a result, also in a slight displacement of the particles of the magnetic powder 200 relative to one another, as well as in slight twisting of the particles. This means that the orientation of the preferred directions of the individual particles can change slightly during the pressing process. In the case of the finished, pressed magnet, on the other hand, the orientations of the preferred directions of the individual particles are permanently fixed relative to one another.

In order to produce such a pressed magnet, it is provided that the preferred magnetic directions of the particles of the powder 200 are determined before permanent fixing, i.e. the preferred directions are aligned before and/or during the pressing in such a way that the magnetic body produced has a large amount in terms of amount has magnetic angular scattering D _PM or a north-south effect W _NS that is strong in terms of amount. In the embodiment according to 3A the alignment takes place with the help of an orientation magnetic field (represented by bold printed field lines), which is generated by an electric coil 161 in the present example. In this example, the axis a161 of the coil 161 runs parallel to the pressing direction, ie to the direction in which the lower punch 110 and/or the upper punch 120 are moved relative to the die 130 during the pressing of the powder 200 .

When the polarization of an element is discussed below, this always means the magnetic polarization that the element in question displays under the influence of an orientation magnetic field when the element is in its intended position in the respective press. According to the example 3A the orientation magnetic field is generated by the coil 161. In principle, however, the orientation magnetic field can also be generated by any other configuration with one or two or more coils, or by one or more permanent magnets, or by a combination of one or more coils with one or more permanent magnets.

In order to produce a permanent magnet with a large magnetic angular spread D _PM in terms of magnitude or a strong North-South effect W _NS in terms of magnitude, the present invention provides for the Adjust the orientation magnetic field so that the flux density on the subsequent hot side of the magnetic powder 200 or the magnetic body to be produced therefrom is significantly greater than on the opposite cold side.

In any case, an orientation magnetic field is generated that is highly inhomogeneous in the volume area of the press cavity 150 or in the volume area of the magnetic powder 200 that is or is to be filled but not yet compacted therein. Due to this orientation magnetic field, the magnetic powder 200 in the press cavity is magnetically aligned, ie each of the particles of the magnetic powder 200 is ideally aligned in the direction that the orientation magnetic field has at the location of the particle in question, provided it is not prevented by other forces becomes. In this way, the orientation magnetic field of the orientation magnetic field present in the press cavity 150 is virtually mapped onto the permanent magnet to be produced. The alignment of the particles of the magnetic powder 200 located in the press cavity 150 takes place before and/or during the Magnetic powder 200 is pressed. Due to frictional forces, especially between the particles of the magnetic powder 200 and due to the compaction caused by the pressing and the associated displacement of the particles relative to each other, the orientation magnetic field is mapped to the permanent magnet to be produced in a good approximation but not completely identically.

As in 3B using the example of the press cavity 150 according to the press 3A is shown, an existing orientation magnetic field H _OM has a local orientation direction at every point in the volume area of the press cavity 150 or at least in the volume area of the magnetic powder filled or to be filled in the press cavity 150, which is represented for some points by stylized compass needles. The orientation magnetic field H _OM along a straight section of a straight line H, which runs within the compression cavity 150 between two end points H1 and H2 located on the edge surface of the compression cavity 150, has a local magnetic field direction dependent on the respective point of the straight section. The tips of the compass needles point in the magnetic north direction of the orientation magnetic field H _OM present at the respective location.

Thus, in a projection plane that is spanned by the straight line H and by a straight line K, which extends in a direction r _K and runs perpendicularly through the center H0 of the straight line section, an angle θ _lok between the Determine the direction r _K and the orthogonal projection of the local magnetic field direction onto the projection plane. The angle θ _lok is in the projection plane, starting from the direction r _K in the mathematically positive direction of rotation (i.e. turning to the left) in an angular range from 0° to 180° exclusively, or in the mathematically negative direction of rotation (i.e. turning to the right) in an angular range of exclusively 0 ° to determine up to and including -180°. The local direction of the orientation magnetic field H _OM is in each case directed from south to north. Proceeding from this, a magnetic angle scattering D _OM can now be determined as follows, which has the orientation magnetic field H _OM along the straight section: $$D_{OM}=\frac{4}{L_H}\cdot {\displaystyle \underset{H1}{\overset{\mathrm{<figure-callout\; id="2"\; label="H"\; filenames="DE102014105172B4\_0028.png,DE102014105172B4\_0048.png"\; state="\{\{state\}\}">H</figure-callout>}2}{\int }}{\mathrm{\theta }}_{lOk}}\left(H\right)\cdot siGn\left(H-H_0\right)\mathrm{i.e}H$$

Where L _H is the length of the straight section of the straight line H between the points H1 and H2 where the straight line H intersects the edges of the press cavity 150, h is a coordinate on the straight section, h ₀ is the coordinate of the center point H0 of the straight section between H1 and H2, and θ _lok (h) is the angle between the direction r _K and the orthogonal projection of the local magnetic field direction at coordinate h onto the projection plane. Also, sign(hh ₀ ) is a function that takes the value '+1' for hh ₀ > 0, '-1' for hh ₀ < 0, and '0' for hh ₀ = 0.

The straight section runs within the compression cavity 150. Optionally, the straight section can also run completely within the volume area occupied by the magnetic powder 200 that has been or is to be filled into the compression cavity 150 but has not yet been compressed.

The position of the straight line segment between points H1 and H2 is therefore selected such that it is located in a volume region of compaction cavity 150 that is filled with magnetic powder after the magnetic powder 200 has been introduced into compaction cavity 150 (apart from the unavoidable gaps between the individual particles of the magnetic powder 200). Thus, after filling the magnetic powder 200, the straight line section intersects the magnetic powder 200. Thus, the magnetic powder 200 is magnetically aligned along the straight line section by the orientation magnetic field H _OM . A high magnetic angular scattering D _OM of the orientation magnetic field H _OM along the straight section is thus mapped onto the magnetic powder 200, ie the individual particles of the magnetic powder 200 are aligned essentially parallel to the orientation magnetic field H _OM acting locally on them and retain this orientation after the subsequent pressing of the magnetic powder 200, apart from small displacements and twists occurring during pressing. As a result, permanent magnets can be produced which have a high magnetic angular spread, as has already been explained above.

In all configurations of the invention, the orientation magnetic field H _OM can optionally be selected such that, when the magnetic powder is filled into the press cavity, there is at least temporarily a field strength of at least 400 kA/m within the volume area of the press cavity and/or within the volume area of the magnetic powder filled into the press cavity having. The orientation magnetic field is effective during compaction at least from a point in time when the particles can be easily rotated until a point in time when the rotatability of the particles is greatly reduced by the progress of the compaction or until the end of the compaction. However, this does not mean that the orientation magnetic field has to have a constant magnitude and/or a constant direction during this period. Rather, it is also possible to use the magnetic powder by several consecutive fields with different directions.

Furthermore, it is pointed out that the magnetic angular spread D _OM of the orientation magnetic field H _OM depends on the choice of the position of the straight line H or the straight line section relative to the press cavity 150 . An orientation magnetic field H _OM can therefore have different magnetic angular spreads depending on the choice of the position of the straight line H or the straight line section.

In addition, it is pointed out that the straight line K can, as shown, run in the pressing direction z, but does not have to. In principle, the straight line K can be oriented in any way. It can, for example, also run perpendicularly to the pressing direction z, or form an angle of more than 0° and less than 90° with the pressing direction z.

To produce a permanent magnet with a strong N/S effect or with a strong magnetic angular spread D _OM , the orientation magnetic field H _OM can be set, for example, in such a way that it has a magnetic angular spread D _OM in the press cavity 150, the magnitude of which is greater than 20°, or even greater than 30°.

In 3A the course of the magnetic flux caused by the magnetic field H _OM of the orientation coil 161 within the magnetic powder 200 is shown schematically using flux lines printed in bold. As can be seen, the flux lines on the hot side to be produced (here on the side of the magnetic powder 200 or the press cavity 150 facing the lower punch 110) have a greater density than on the cold side to be produced (here on the upper punch 120 facing side of the magnetic powder 200 or the press cavity 150).

One way of generating a highly inhomogeneous orientation magnetic field H _OM within the press cavity 150 or within the volume area occupied by the magnetic powder 200 filled or to be filled into the press cavity 150 is optionally to form the walls of the press cavity 150 by sections, which have different magnetic polarizations under the influence of the orientation magnetic field H _OM . These polarizations depend on the permeability, the field strength of the orientation magnetic field H _OM and the saturation polarization of the material from which the respective section is formed.

One of these walls can be the pressing surface 110p of the lower punch 110, and another wall can be a pressing surface 120p of the upper punch 120 of the guide channel formed in the die 130 for guiding the lower punch 110 is located. Correspondingly, the side of the upper punch 120 that faces the pressing cavity 150 and is located within the guide channel formed in the die 130 for guiding the upper punch 120 is regarded as the pressing surface 120p of the upper punch 120 . 4A shows a plan view of the pressing surface 110p of the lower punch 110, 4B a plan view of the pressing surface 120p of the upper punch 120.

According to the example 3A the lower stamp 110 is composed of at least two sections 111, 112 which have different magnetic polarizations under the influence of an orientation magnetic field and can thereby influence the course of the magnetic flux. The arrangement of the different sections 111, 112 can be chosen so that - as in 4A is shown - each of the at least two different sections 111, 112 forms part of the pressing surface 110p of the lower punch 110. A section of the pressing surface 110p is formed by a surface section 111p of section 111, another section 112p by a surface section 112p of section 112.

The materials for the sections 111, 112 of the lower punch 110 can optionally be selected so that one of these sections 111, 112 under the influence of an orientation magnetic field H _OM has a higher or, alternatively, - as for example in 3A - has a lower polarization than the other (if the lower punch 110 has only two sections) or than another (if the lower punch 110 has more than two sections) of the sections 111, 112 under the influence of the same orientation magnetic field generated by the coil 161 HO _OM . If the pressing surface 110p of the lower punch 110 is composed of the surface sections 111p, 112p of two or more such sections 111, 112, the area proportion of that of the sections 111, 112 forming the pressing surface 110p, that of all of these sections 111, 112 under the influence of an orientation magnetic field H _OM has the greatest amount of polarization on the pressing surface 110p, be greater than or equal to 20% and/or less than or equal to 80%. To determine the pressing area, the actual area is to be used in each case and not its projection onto a plane that is perpendicular to the pressing direction, for example. This is particularly important for configurations in which the pressing surface 110p is not flat.

As also in 3A is shown, the upper punch 120 (located here on the cold side to be produced) or - as in 4B is shown - at least the pressing surface 120p optionally consist of a uniform material which has a low magnetic polarization under the influence of an orientation magnetic field H _OM or be non-magnetic. Alternatively, however, the upper punch 120 could also have a two-part or multi-part structure, as has already been explained for the lower punch 110 . Conversely, the lower punch 110 would have the properties of the present upper punch 120.

As continues in 3A shown, in addition to or as an alternative to a lower punch 110 and/or upper punch 120 composed of two or more different materials, one or more magnetic flux guide pieces 140 can also be used which, under the influence of an orientation magnetic field H _OM , have a different magnetic polarization than the die 130 Such flux guide pieces 140 also serve to favorably influence the course of the magnetic flux in the press cavity 150 filled with the powder 200 . In the example shown, the flux guide piece or pieces 140 are inserted into the die 130 . The flux guide piece(s) 140 in the die 130 can optionally be exchangeable, so that the same die 130 can be used to produce magnets with different flux guide pieces 140 with different levels of magnetic angular dispersion D _PM or with different pronounced north-south effects. The flux guide piece(s) 140 can optionally be made of a uniform, homogeneous material. However, it is also possible to assemble one, several or all of the flux guides 140 from different parts, of which at least two have different magnetic polarizations under the influence of an orientation magnetic field H _OM , as has already been explained by way of example using the parts 111, 112 of the lower punch 110 . Furthermore, an optional magnetic yoke 145, for example made of iron, can be provided, which magnetically couples the flux conducting piece 140 or the flux conducting pieces 140 to the lower punch 110.

At the in 3A In the example shown, the hot side of the magnetic body to be produced is produced on the side of the press cavity 150 or of the magnetic powder 200 filled therein which faces the lower punch 110 . The multi-part lower punch 110 is therefore designed in such a way that the side of the lower punch 110 facing the pressing cavity 150 or the magnetic powder 200 filled therein has a lower magnetic flux density in the area of the first section 111 than in the area of the section 112. This can be achieved in particular as a result that the first section 111 under the influence of an orientation magnetic field H _OM has a lower magnetic polarization than the second section 112 under the influence of the same orientation magnetic field H _OM . For example, the first section 111 can be non-magnetic and/or the second section 112 can be pressed under the influence of an orientation magnetic field H _OM generated by the coil 161 and at a pressing temperature of e.g. B. 20 ° C have a magnetic polarization of more than 0.8 T or more than 1.5 T. In the context of the present application, “non-magnetic” refers to substances that have a polarization of less than 0.1 T at the pressing temperature of the relevant section under the influence of a magnetic field with a strength of 800 kA/m. This corresponds, for example, to a permeability of µ = 1.1 if the material has a linear magnetization curve, or a maximum proportion of about 5% alpha-Fe in steel that is intrinsically “non-magnetic”.

Irrespective of this, the upper punch 120 can have a low magnetic polarization, for example less than 0.4 T, or be non-magnetic under the influence of an orientation magnetic field H _OM , since this is located on the cold side of the magnetic body to be produced in the present example.

Accordingly, one, several or each of the flux guides 140 can have a magnetic polarization during the pressing process under the influence of an orientation magnetic field H _OM that is higher than the magnetic polarization of the die 130. For example, one, several or each of the flux guides 140 can the influence of an orientation magnetic field H _OM have a magnetic polarization that is at least 0.8 T or at least 1.5 T greater than the magnetic polarization of the matrix 130. For example, one, several or each of the flux guide pieces 140 under the Influence of an orientation magnetic field H _OM and at the pressing temperature of z. B. 20 ° C have a magnetic polarization of more than 0.8 T or more than 1.5 T, and / or the matrix 130 can under the influence of the orientation magnetic field H _OM a magnetic polarization of less than 0.4 T or less than 0.1 T.

The values given in the preceding exemplary embodiment also apply in principle to all other configurations of the invention, in particular also to any other presses.

The 5A until 5F show examples of different possible configurations Lower punch 110, as can be used in any press for the production of magnets with a high magnetic angular spread D _PM or with a strong north-south effect, using the example of FIG 3A explained press 100. To the extent that the following description of this lower punch 110 refers to the magnetic polarization of the relevant lower punch 110 or a section 111, 112, 113, this information refers to the polarization that is in the relevant lower punch 110 or in the relevant section 111, 112, 113 when the associated lower punch 110 is inserted into the press 100 and the orientation magnetic field H _OM acts on it. If different sections 111, 112, 113 in a lower punch 110 are identified by the same reference numbers, these sections show the same magnetic polarization under the influence of the same orientation magnetic field H _OM . This can be achieved in particular in that the individual sections marked with the same reference number are made of the same material.

The lower stamp 110 according to 5A corresponds to that already in the 3A and 4A explained lower stamp 110.

the inside 5B Lower punch 110 shown differs from lower punch 110 according to FIGS 3A , 4A and 5A in that a further section 113 is arranged between adjacent sections 111 and 112, the magnetic polarization of which, under the influence of an orientation magnetic field H _OM , is greater than the magnetic polarization of section 111 adjoining section 113 in question, but smaller than the magnetic polarization of the section 112 adjoining the section 113 in question. In this way, a softer transition from the flux density at section 111p and the flux density at section 112p can be achieved on the pressing surface 110p of the lower punch 110. Such a softer transition can advantageously reduce the risk of cracks occurring in the permanent magnet to be manufactured.

Further variants with which an all too sudden change in the magnetic flux density on the pressing surface 110p can be prevented are described in FIGS 5C until 5F shown.

According to the lower stamp 110 5C the pressing surface 110p is formed by a further section 113 which covers the other sections 111 and 112 of the lower punch 110. When the orientation magnetic field H _OM is present, this results in a smoothing of the course of the magnetic polarization of the lower punch 110 near the pressing surface 110p. The smoothing effect is greatest when, under the influence of the orientation magnetic field H _OM , the polarization of section 113 corresponds approximately to the polarization of magnetic powder 200 or green body (=pressed but still unsintered magnetic powder). In principle, however, a section 113 can also consist of a non-magnetic or very highly permeable material. The smoothing effect is based, among other things, on the fact that the sections 111 and 112 are spaced apart from the magnetic powder 200 during the pressing process by the section 113 that provides the pressing surface 110p.

the inside 5D Lower punch 110 shown differs from lower punch 110 according to FIGS 3A , 4A and 5A in that the edges of the section(s) 112 facing the pressing cavity 150, which under the influence of an orientation magnetic field H _OM have a higher magnetic polarization than the sections 111, are bevelled and the section(s) 111 extend into the area of the is located between the pressing surface 110p and the chamfer or chamfers.

5E shows a similar lower punch 110, which differs from the lower punch 110 according to FIG 5D differs only in that the chamfering is not oblique but rounded.

At yet another, in 5F shown example, as well as the example according to FIG 5C , both the edges of the part(s) 112 facing the pressing cavity 150 and the edges of the part(s) 111 facing the pressing cavity 150 are chamfered and covered by a further part 113, which adjoins all of the parts 111 and 112. The sections 113 according to the 5C and 5F act in the same way and are subject to those already referred to 5C explained properties.

In order to separate different sections 111, 112 (see Fig 6A and 7A ) or 111, 112, 113 (see the 6B and 7B ) of a lower stamp 110 to be mechanically connected to one another, any desired connection techniques can be used between adjacent partial layers 111, 112, 113. For example, pinning or soldering or dovetail connections are suitable as connection techniques.

With the lower stamps 110 according to the 6A and 7A are the respective connections between the adjacent sections 111 and 112 realized, in the case of the lower punches 110 according to the 6B and 7B between adjoining sections 111 and 113, and between the adjoining sections 112 and 113. The views according to FIGS 6A and 7A represent horizontal sections, such as those in the section planes E1-E1, E3-E3, E4-E4, E5-E5 and E6-E6 5A , 5C , 5D , 5E or. 5F may exist, and the views according to 6B and 7B represent horizontal sections, as they are, for example, in the section plane E2-E2 5B may exist.

Another possibility is to connect different sections 111, 112, 113 to one another by shrinking them on. In this case, one of the sections can enclose one or more other sections in the form of a closed ring. According to the example 7A the section 111 encloses the section 112 annularly, and in the example according to FIG 7B Section 111 encloses sections 112 and 113 annularly, and section 113 encloses section 112.

In the case of the lower stamp 110 according to the 6A and 6B the outer section 111 does not completely enclose the inner sections 112 or 112 and 113 in the area of the pressing surface 110p. In the case of the lower stamp 110 according to the 7A and 7B the outer section 111 is designed as a closed ring, which encloses the inner sections 112 or 112 and 113 at least in the area of the pressing surface 110p, and the section 113, which is also designed as a closed ring, encloses the inner section 112 at least in the area of the Pressing surface 110p annular. As a result, the pressing surface 110p is formed by surface sections of at least two sections which have different polarizations under the influence of an orientation magnetic field H _OM .

With the orders 6A and 6B magnets are produced which only in the direction perpendicular to the boundary surfaces between the sections 111, 112 and 113 have a high magnetic angular spread D _PM in terms of absolute value or a strong N/S effect W _NS in terms of absolute value.

With the lower stamps 110 according to the 7A and 7B the inner section 112 or 112 and 113 is surrounded in a ring shape by the respective outer sections 111 . In this case, in all directions that are perpendicular to the magnetic axis, a magnetic angle scattering D _PM that is high in terms of absolute value or an N/S effect W _NS that is strong in terms of absolute value is generated.

A further influencing of the course of the orientation magnetic field H _OM in the area of the press cavity 150 or the course of the magnetic flux in the magnetic powder 200 located in the press cavity 150 can be achieved by the material of the stamp 110 or 120, which is explained below using the 8A until 8C is explained using the example of an upper punch 120, in which the course of the flux lines is shown schematically in each case with the aid of bold lines. According to the example 8A For example, the upper punch 120 has a magnetic polarization under the influence of an orienting magnetic field H _OM that is greater than the magnetic polarization of the powder 200 and the die 130 under the influence of the same orienting magnetic field H _OM . According to the example 8C the upper punch 120 is essentially non-magnetic, and the magnetic polarization of the upper punch 120 occurring under the influence of an orientation magnetic field H _OM is smaller than the magnetic polarization of the die 130 and the powder 200 occurring under the influence of the same orientation magnetic field H _OM . In the example according to 8B finally, the magnetic polarization of the upper punch 120 occurring under the influence of an orientation magnetic field H _OM is greater than zero and greater than the magnetic polarization of the upper punch 120 occurring under the influence of the same orientation magnetic field H _OM according to FIG 8C , but smaller than the magnetic polarization of the upper punch 120 occurring under the influence of the same orientation magnetic field H _OM according to FIG 8A . In addition, the magnetic polarization of the upper punch occurring under the influence of the same orientation magnetic field H _OM according to 8B similar to the magnetic polarization of the powder 200 occurring under the influence of the same orientation magnetic field H _OM .

A further configuration of a press 100 for the production of a pressed permanent magnet with a high magnetic angular spread D _PM in terms of amount or with a strong north-south effect W _NS in terms of amount is shown in FIGS 9A in horizontal section and 9B in vertical section. According to the view 9B corresponds to the in 9A shown section plane E7, the view according to 9A the in 9B illustrated cutting plane E8. The press 100 has a die 130 with a press cavity 150 into which a magnetic powder 200 is filled. The orientation magnetic field H _OM for aligning the individual particles of the magnetic powder 200 is generated with the aid of two coils 161 and 162 which are arranged coaxially to one another and are spaced apart from one another and into which an optional coil core 171 or 172 is inserted. As shown by way of example with this structure, the axes a161 and a162 of the coils 161 and 162, respectively, can be perpendicular to the pressing direction (z/-z). Optionally, the axes a161 and a162 can be identical.

The two coils 161 and 162 are connected in such a way that an electric current flows through them in the same direction during operation, which means that the first partial magnetic field generated by the first coil 161 points in the same direction in the center of the first coil 161 like the second partial magnetic field generated by the second coil 162 in the center of the second coil 162. The orientation magnetic field H _OM is created by the superposition of the first partial magnetic field and the second partial magnetic field. Optionally, the coils 161 and 162 can have the same number of turns and/or currents of the same strength can flow through them during operation.

The die 130 with the press cavity 150 and the magnetic powder 200 filled in the press cavity 150 is arranged between the two coils 161 and 162 . Also arranged between the two coils 161 and 162 are two magnetic conductor pieces 140 and 141. Furthermore, an optional magnetic yoke 145, for example made of iron, is provided, which magnetically couples the coil core 171 to the coil core 172. The first guide piece 140, which is inserted into the die 130, is located between the coil 161 and the pressing cavity 150, and it extends in a direction perpendicular to the axes of the coils 161, 162 and perpendicular to the pressing direction (z/-z). Direction y over a smaller area than the press cavity 150. This has the effect that the magnetic flux density on the first conductive piece 140 facing first side 151 of the press cavity 150 or the magnetic powder 200 is locally increased in a partial area of this first side 151.

In contrast, the second conductor piece 141 extends in the same direction y perpendicular to the axes of the coils 161, 162 and perpendicular to the pressing direction (z/-z) over a larger area than the pressing cavity 150. This in turn causes the magnetic flux density on the second side 152 of the press cavity 150 or of the magnetic powder 200 facing the second guide piece 141 is reduced in a partial region of this second side 152 .

As a result, the magnetic flux density on a partial area of the first side 151 assumes a maximum value that is higher than the maximum value of the magnetic flux density on the second side 152. The course of the field lines is therefore from the first side 151 to the second Page 152, which leads to a pressed magnet with the desired, high absolute value magnetic angular spread D _PM or the desired, high absolute value north-south effect, if the magnetic powder 200 in the press cavity 150 with an applied orientation field (i.e. if the first coil 161 and the second coil 162 are energized as described) between the lower punch 110 and the upper punch 120 is compressed. The generated angular magnetic scatter is more pronounced in the y-direction than in the z-direction. Under the influence of the H _OM orientation magnetic field, the stamps used have a magnetic polarization that is less than or equal to the polarization of the powder.

In addition to the taper in the y-direction, the flux guide 140 can also be shorter in the z-direction than the height of the press cavity 150. In addition, the flux guide 141 can also be longer in the z-direction, similar to the y-direction than the height of the press cavity 150. Optionally, the coil core 172 can have a larger cross section than the coil core 171. With this arrangement, a magnet with a high N/S effect WNS and/or with a high magnetic angle dispersion D _PM can be produced with this arrangement. The angular spread D _PM is approximately equally pronounced in the y and z directions. A further increase in the angular scattering in the z-direction can be achieved by using stamps which are at least partially made of a material which, under the influence of the orientation magnetic field HOM, has a magnetic polarization which is greater than the polarization of the matrix and the powder.

_FIGS 10A in horizontal section and 10B and 10C in vertical section. According to the view 10B corresponds to the in 10A shown cutting plane E9, the view according to 10C the in 10A shown section plane E10, and the view according to 10A the in the 10B and 10C illustrated cutting plane E11.

The press 100 in turn has a die 130 with a press cavity 150 into which a magnetic powder 200 is filled. The orientation magnetic field H _OM for aligning the individual particles of the magnetic powder 200 is generated by means of three coils 161, 163 and 164. The axes of the coils 161, 163 and 164 are labeled a161, a163 and a164, respectively.

The spaced-apart coils 163 and 164, in which an optional coil core 173 or 174 is inserted, can—as shown—be arranged coaxially to one another. Furthermore, an optional magnetic yoke 145 , for example made of iron, is provided, which magnetically couples the coil core 173 to the coil core 174 . As shown with this structure as an example, both the axis a161 of the coil 161 and the axes a163 and a164 of the coils 163 and 164, respectively, run perpendicular to the pressing direction (z/-z). In addition, axis a161 can be perpendicular to both axis a163 and axis a164.

The two coils 163 and 164 are switched in such a way that an electric current flows through them in opposite directions during operation, which means that the partial magnetic field generated by the coil 163 in the center of the coil 163 points in the opposite direction to that partial magnetic field generated by the coil 164 in the center of the coil 164. Optionally, the coils 163 and 164 can have the same number of turns and/or currents of the same strength can flow through them during operation and/or have the same coil cross section and/or the same amount ( generate maximum) magnetic flux. Any two or three of these features linked to one another by “and/or” can be implemented in combination with one another, or just any one of these features can be implemented, or else all of these features.

The coil 161 in turn is energized in such a way that part of the magnetic flux it generates is conducted through the coil 163 and another part of the magnetic flux it produces is conducted through the coil 164 . Optionally, these parts can be of the same size and/or their total can correspond to the flux generated by coil 161 .

The die 130 with the press cavity 150 and the magnetic powder 200 filled in the press cavity 150 is arranged between the two coils 163 and 164 . Magnetic conducting pieces 140, 143 and 144 are inserted into the die 130. The conducting piece 140 is arranged between the pressing hollow 150 and the coil 161, the conducting piece 143 between the pressing hollow 150 and the coil 163, and the conducting piece 144 between the pressing hollow 150 and the Coil 164.

The conductive piece 140 extends in a direction (y) perpendicular to both the axis a161 of the coil 161 and perpendicular to the pressing direction (z/-z) over a smaller area than the pressing hollow 150. This causes the magnetic flux density on the side 151 of the press cavity 150 or of the magnetic powder 200 facing the guide piece 140 is locally increased in a partial area of this side 151 .

Furthermore, the magnetic sub-fields generated by coils 163 and 164 are directed essentially in opposite directions, at least in the region of compression cavity 150 and thus of magnetic powder 200, which means in particular that the magnetic flux density on the side of compression cavity 150 or of the magnetic powder 200 contained therein is reduced. As a result, the magnet produced from magnetic powder 200 exhibits a high magnetic angular spread D _PM in terms of absolute value or a strong north-south effect in terms of absolute value, with the hot side being represented by its side facing conductive piece 140 and the cold side being represented by its side facing conductive piece 140 opposite side is formed.

Similar to the arrangement according to the 9A and 9B Here, too, the flux guide pieces 140, 143 and 144 can also be shorter in the z-direction than the length of the press cavity 150 in order to achieve a strongly pronounced, high-magnitude magnetic angular spread D _PM in both the y- and z-direction.

Based on 11A until 11D it is explained below by way of example how at least two magnets each made from a pressed magnetic powder 200, 200' can be produced simultaneously by means of a press 100 during a single stroke of the press 100, which means a significantly increased output.

According to the view 11B corresponds to the in 11A shown section plane E12, the view according to 11C the in 11A shown section plane E13, and the view according to 11A the in the 11B and 11C illustrated cutting plane E14.

The press 100 has a die 130 with two press cavities 150 and 150' spaced apart from one another, in each of which a magnetic powder 200 or 200' to be pressed is filled. The orientation magnetic field H _OM for aligning the individual particles of the two magnetic powders 200, 200' is generated by means of two coils 161,162. The axes of the coils 161 and 162 are labeled a161 and a162, respectively.

The spaced-apart coils 161 and 162, in which an optional coil core 171 or 172 is inserted, can—as shown—be arranged coaxially to one another. Furthermore, an optional magnetic yoke 145, for example made of iron, is provided, which magnetically couples the coil core 171 to the coil core 172. As exemplified with this structure, both the axis a161 of the coil 161 and the axis a162 of the coils 162 may be perpendicular to the pressing direction (z/-z).

The two coils 161 and 162 are connected in such a way that an electric current flows through them in the same direction during operation, which results in the partial magnetic field generated by the coil 161 in the center of the Coil 161 points in the same direction as the partial magnetic field generated by coil 162 in the center of coil 162. Optionally, coils 161 and 162 can have the same number of turns and/or currents of the same strength can flow through them during operation.

The die 130 with the pressing cavities 150 and 150' and with the magnetic powders 200 and 200' filled into the pressing cavities 150, 150' is arranged between the two coils 161 and 162. Magnetic flux conducting pieces 140, 140', 142 and 143 are inserted into the die 130. The conducting piece 140 is arranged between the pressing hollow 150 and the coil 161, the conducting piece 140' between the pressing hollow 150' and the coil 162 Guide pieces 142 and 143 each have an end section 142e or 143e on their mutually facing sides, which is arranged between the two press hollows 150 and 150'. As shown, the flow guide pieces 142 and 143 can be spaced apart from the two press cavities 150, 150'. However, it is also possible that their end sections 142e and/or 143e reach up to the compression cavity 150 and 150' and thus form part of the inner wall of the compression cavity 150 and 150', which is illustrated by the otherwise identical arrangement according to FIG 11D is shown.

Each of the guide pieces 140 and 140' extends in a direction (y) perpendicular to the axes a161 and a162 of the coils 161 and 162, respectively, and perpendicular to the pressing direction (z/-z) over an area less than the one of the press cavities 150 and 150' which is closest to the respective guide piece 140, 140'. In addition, since each of the guide pieces 140, 140', 142, 143 under the influence of an orienting magnetic field H _OM has a magnetic polarization that is higher than the magnetic polarization of the matrix 130 and the powder 200 under the influence of the same orienting magnetic field H _OM magnetic flux density on the side 151 of the press cavity 150 or of the magnetic powder 200 facing the conductive piece 140 increases locally in a partial area of this side 151 . Correspondingly, the magnetic flux density on the side 151' of the press cavity 150' or of the magnetic powder 200' facing the conductor piece 140' is locally increased in a partial area of this side 151'. In contrast, the guide pieces 142 and 143 on the mutually facing sides 152 and 152' of the press hollow 150 and 150' or the magnetic powder 200 and 200' cause a reduction in the magnetic flux density compared to the flux density on the sides 151 and 151'.

As a result, the magnetic flux density on the first side 151 of the press cavity 150 or of the magnetic powder 200 facing the conductive piece 140 is locally increased in a partial area of the side 151 . The maximum value that the magnetic flux density has in the area of side 151 can be higher than any magnetic flux density that occurs in the area of side 152 . Accordingly, the maximum value exhibited by the magnetic flux density in the area of side 151' can be higher than any magnetic flux density occurring in the area of side 152'. The flux densities in the area of sides 151 and 152 are each to be determined within the magnetic powder 200, and the flux densities in the area of sides 151' and 152' are each to be determined within the magnetic powder 200'.

The magnets pressed with such a press 100 from the powders 200 or 200' each have a high magnetic angular spread D _PM in terms of absolute value or a north-south effect that is large in terms of absolute value, with the magnet produced from the powder 200 being the hot side formed by the side facing the conductive piece 140 and the cold side by the side facing away from the conductive piece 140, and in the case of the magnet made from the powder 200' the hot side is formed by the side facing the conductive piece 140' and the cold side is formed by the side facing away from the guide piece 140'.

In principle, it is possible during one stroke of a press 100 to simultaneously produce two or more identical green compacts or identical powder-pressed magnets, which therefore have geometrically identical shapes and an identical distribution of the magnetic field. The press 100 according to FIG 12 . Here, four press cavities 150, 150', 150" and 150"' are arranged in the die 130, which are filled with a magnetic powder 200, 200', 200" or 200"'. The arrangement of the press cavities 150, 150 ', 150" and 150"' in the matrix 130 is mirror-symmetrical with respect to two different planes of symmetry SE1 and SE2. These planes of symmetry SE1 and SE2 can optionally run perpendicular to one another. This is achieved by the coils 161 and 162 in connection with the coil cores 171 and 172 and the flux guide pieces 140 and 140' is mirror-symmetrical to both the plane of symmetry SE1 and to the plane of symmetry SE2. This enables the production of two or more magnets that are identical and/or mirror-symmetrical with regard to their geometric shape and the distribution of their magnetic field the press hollows 150, 150′, 150″ and 150′″ for the production of these magnets are also arranged mirror-symmetrically to the planes of symmetry SE1 and SE2.

In the present example, the press cavity 150 is mirror-symmetrical with respect to the plane of symmetry SE1 to the press cavity 150' in the material rize 130 arranged. Correspondingly, the press cavity 150" is arranged mirror-symmetrically to the press cavity 150"' in the die 130 with respect to the plane of symmetry SE1. Furthermore, the press cavity 150 is arranged mirror-symmetrically to the press cavity 150" in the die 130 with respect to a plane of symmetry SE2, and the press cavity 150' is arranged in mirror symmetry with respect to the pressing cavity 150''' in the die 130 with respect to the plane of symmetry SE2.

In principle, two, three, four or more magnets can be produced simultaneously during a single pressing stroke in this or a corresponding manner. At least one upper punch and/or one lower punch is used to press each magnetic powder 200, 200', 200" or 200"' located in the press cavity 150, 150', 150" and 150"'. In the case of several upper punches, these can be movable independently of one another, or they can be rigidly connected to one another and/or formed in one piece. Likewise, in the case of several lower punches, these can be movable independently of one another, or can be rigidly connected to one another and/or formed in one piece.

If at least one first permanent magnet and a second permanent magnet that is (geometrically and magnetically) symmetrical to this are produced, the course of the orientation magnetic field H _OM within the press cavity for the first permanent magnet is with respect to at least one plane of symmetry (e.g. SE1 and/or SE2 ) from a first point in time to a second point in time continuously mirror-symmetrical to the profile of the orientation magnetic field H _OM within the press cavity for the second permanent magnet. The first point in time is given by the moment after the filling of the magnetic powder into the respective press cavity at which the orientation magnetic field H _OM is present. The second point in time is given by the end of the pressing (reaching of the green density) of the magnet powder located in the two press cavities. Regarding the plane of symmetry SE1, this criterion can apply, for example, to the permanent magnets produced with the press hollows 150 and 150', and/or to permanent magnets produced with the press hollows 150" and 150'''. Regarding the plane of symmetry SE2, this criterion can, for example, apply to the with the permanent magnets produced with press hollows 150 and 150" and/or permanent magnets produced with press hollows 150' and 150"'.

As an alternative or in addition to mirror symmetry with respect to a first plane of symmetry SE1 and/or a second plane of symmetry SE2, the course of the orientation magnetic field H _OM within the press cavity for the first permanent magnet with respect to an axis of symmetry SA from the first point in time to the second point in time can have uninterrupted two-fold rotational symmetry with the course of the Orientation magnetic field H _OM be within the press cavity for the second permanent magnet. This two-fold rotational symmetry with respect to the axis of symmetry SA means that the course of the orientation magnetic field H _OM within the press cavity for the first permanent magnet after a rotation of 180° around the axis of symmetry SA corresponds to the course of the (unrotated) orientation magnetic field H _OM within the press cavity for the second permanent magnet . This is equivalent to the fact that the course of the orientation magnetic field H _OM inside the press cavity for the first permanent magnet is mirror-symmetrical with respect to the axis of symmetry SA to the course of the orientation magnetic field H _OM inside the press cavity for the second permanent magnet. The axis of symmetry SA thus represents both an axis of rotation and an axis of reflection. The criterion mentioned can apply, for example, to the permanent magnets produced with the press hollows 150 and 150''' and/or for permanent magnets produced with the press hollows 150' and 150".

The criteria relating to the symmetry of the orientation magnetic field H _OM are only to be understood as optional. With the methods described here, the magnetic powder filled into these press cavities can of course also be simultaneously magnetically aligned by means of two or more press cavities arranged in a common die, without one of the described symmetries of the orientation magnetic field H _OM being present.

Assuming the same filling quantities of the press cavity in question and the same amount of pressing of the magnetic powder filled in, permanent magnets can be produced with such symmetries of the orientation magnetic field H _OM , which have the same shape and in which the permanent magnetic field provided by them, based on the shape of the magnet, has the same course of the permanent magnetic field. Such permanent magnets are therefore identical. This can be achieved, for example, by both the two press hollows used for production and the orientation magnetic field H _OM being axisymmetric to an axis of symmetry SA. However, it is also possible to produce permanent magnets which are mirror-symmetrical with respect to a plane of symmetry SE1, SE2, both with regard to their shape and with regard to the permanent magnetic field provided by them. Such permanent magnets are not generally identical, although they can be identical.

The following is based on the 13A and 13B another method is explained how a powder-pressed magnet can be produced in a particularly simple manner, in that a coil arrangement 161, 162, which is already present for generating an orientation magnetic field H _OM , is also used to fill the magnetic powder 200 into a press cavity 150. 13A 1 shows, by way of example, the simultaneous filling of two press cavities 150, 150′, which are arranged together in the same die, with the die not being shown for reasons of clarity. 13B shows an example of the magnetic alignment of the magnetic powder 200 caused by the action of the orientation magnetic field H _OM in the press cavity 150, 150' closed by the upper punch. The arrangement of the press cavity 150, 150' in the die can, for example, be as in the arrangement according to FIG 11A until 11C .

13A shows the arrangement during the filling of the magnetic powder 200 into the two press cavities 150, 150'. For this purpose, the die 130 has a filling opening 131 or 131' for each of the press cavities 150, 150'. A filling funnel 210, also referred to as a “filling shoe”, is used for filling, which has an outlet opening on its underside for each of the compression hollows 150, 150′. Alternatively, a separate hopper can also be used for each press cavity 150, 150'. The outlet openings can optionally be opened and closed as required via a slide or the like, not shown. The magnetic powder 200 is initially in the filling hopper 210. In order to fill the press hollows 150, 150' with the magnetic powder 200, a filling magnetic field H _F is generated by means of the coil arrangement 161, 162. For this purpose, the coil arrangement 161 , 162 is in a first relative position with respect to the matrix 130 . The first relative position is selected in such a way that the filling magnetic field H _F at the respective filling opening 131 or 131' has a large gradient, as a result of which a magnetic force acts on the particles of the magnetic powder 200 in the filling hopper 210, through which the respective area The particles of the powder 200 located at the outlets of the hopper 210 are driven into the associated press cavity 150, 150'. The filling magnetic field H _F thus supports the filling of the press cavity 150, 150' with the magnetic powder 200.

If z is the pressing direction and H _Fx is a transverse component of the filling magnetic field H _F in a direction x perpendicular to the pressing direction z, then the product H _FX · ∂H _Fx /∂z from the transverse component H _Fx and the gradient can be used as a measure of the filling force ∂H _Fx /∂dz of the transverse component H _Fx in pressing direction z. Based on this equation, the location of the absolute maximum filling force can be estimated by measuring the course of the field in the press cavity 150, 150'. The “filling force” is understood to mean the force caused by the filling magnetic field H _F and acting on the magnetic powder 200 parallel to the pressing direction z. Optionally, the first relative position can be selected such that the location of the maximum amount of filling force in the pressing direction z is at the level of the filling opening 131, 131'. The location of the maximum filling force can also be determined, for example, by measuring the filling magnetic field H _F (ie measuring its component in the z-direction) in air.

Alternatively or additionally, the position of the location of the maximum filling force can also be determined by simulation, e.g. using finite elements, and/or by measuring the force acting on the powder, and/or by completely measuring the filling magnetic field with subsequent calculation of the resultant location of maximum filling power.

Irrespective of the way in which the location of the maximum filling force is determined, it is fundamentally advantageous if the location of the maximum filling force caused by the filling magnetic field H _F is at the upper edge of the die.

For filling a press cavity 150, 150', which, perpendicular to the pressing direction z, can have, for example, an internal width (ie measured from inner wall to inner wall) of less than or equal to 10 mm or even less than or equal to 5 mm, but also for press cavities with larger internal width, the product µ ₀ ² · H _F (x) · ∂H _Fx /∂z at the point of maximum filling power z. B. be at least 40 T ² / m. For example, the product may range from up to 40 T ² /m to 50 T ² /m. The vacuum permeability is denoted by µ ₀ here. It is µ ₀ = 12.566 * 10 ^-7 V s/(A m).

After the press hollows 150, 150' have been filled with the magnetic powder 200 in this way, the magnetic powder 200 in the respective press hollow 150, 150' is aligned with the aid of an orientation magnetic field Ho and pressed into a magnetic body in the aligned state, as already described above became. The orientation magnetic field H _OM is generated using the same coil arrangement 161, 162 that was already used to generate the filling magnetic field H _F . However, during the magnetic alignment of the magnetic powder 200 with respect to the die 130, the coil arrangement 161, 162 is in a second relative position which is different from the first relative position, which results in 13B is shown. In order to switch from the first relative position to the second relative position or back, the press can, for example, have a yoke that can be adjusted relative to the die 130 senior This can e.g. B. be given by the coil cores 171 and 172, and / or by one or more flux guide pieces, via which the magnetic flux to the press cavity 150, 150 'is conducted.

After filling the magnetic powder 200 into the press cavities 150, 150', the hopper 210 can be removed from the filling position so that it does not interfere with the press dies, which are used as described below. For example, the hopper 210, unlike in 13B shown, can also be shifted in the y-direction and thereby release the filling openings, so that there is no obstruction of the upper punch or punches 120, 120'.

As in 13B shown, for each of the dies 150, 150' there can be a pair having a lower punch 110, 110' and an upper punch 120, 120'. These stamps 110, 110', 120, 120' represent pressing stamps, with which the powder located in the pressing cavity 150 or 150' is pressed into a respective magnet. Instead of a pair of punches 110 and 120 or 110' and 120', only one punch 110 or 120 or 110' or 120' could be present per press cavity 150 or 150'. In any case, for each press cavity 150, 150', at least one press ram can be adjusted in a press direction z relative to the die 130 (shown here only schematically using dashed lines).

Unless, as in the 13A and 13B shown, work is carried out simultaneously with at least two press cavities 150 and 150', the filling magnetic field used to fill all of the press cavities 150, 150', 150", 150''' can also be measured with respect to a first plane of symmetry SE1 and/or a second plane of symmetry SE2 during the have a mirror symmetry throughout the filling process.This means that in the first relative position the profile of the filling magnetic field within the compression cavity for the first permanent magnet is continuously mirror-symmetrical with respect to at least one plane of symmetry (e.g. SE1 and/or SE2) to the profile of the filling magnetic field within the compression cavity For the second permanent magnet Regarding the plane of symmetry SE1, this criterion can apply, for example, to the permanent magnets produced with the pressed hollows 150 and 150', and/or for permanent magnets produced with the pressed hollows 150'' and 150'''. Regarding the plane of symmetry SE2, this criterion can apply, for example, to the permanent magnets produced with the pressed hollows 150 and 150'', and/or for permanent magnets produced with the pressed hollows 150' and 150'''.

The criteria relating to the symmetry of the filling magnetic field are only to be understood as optional. Of course, with the magnetic filling method described here, two or more press cavities arranged in a common die can also be filled simultaneously with a magnetic powder without one of the described symmetries of the filling magnetic field being present.

Unless, as in the 13A and 13B shown, work is carried out simultaneously with at least two press cavities 150 and 150', in order to achieve magnets with a homogeneous magnetic field, at least while the orientation magnetic field H _OM is acting on the magnetic powder located in the press cavities 150, 150', a flux guide piece 147 can be installed between the press cavities 150 and 150 150' are placed, which in 14 is shown. The flux guide piece 147 can also be arranged in the die 130 . In addition, the flux guide piece 147 can consist of one of the materials that have the material properties that have already been explained for the flux guide pieces 140 to 146 . In particular, the flux conducting piece 147 can have a greater magnetic polarization than the matrix 130 under the influence of the orientation magnetic field H _OM . Magnets produced in this way have no or only a small amount of north-south effect or no or only a small amount of magnetic angular dispersion D _PM up. Depending on the desired requirements, the presence and possibly the strength of an N/S effect can be adjusted by adjusting the widths of the flux guide pieces 140 to 147 (if used).

To produce such homogeneous magnets, the orientation magnetic field H _OM can be designed such that in the second relative position for each of the press hollows 150, 150' the following applies: for any first point ST1 within the press hollow 150, 150' in question and for any of the first point ST1 different second point ST2 within the same press cavity 150, 150 'is the magnitude of the orientation magnetic field H _OM at the first point ST1 greater than 0.95 times the magnitude of the orientation magnetic field H _OM at the second point ST2, and the direction of the orientation magnetic field H _OM at the first point ST1 and the direction of the orientation magnetic field (H _OM ) at the second point ST2 differ by no more than 5°.

So that the flux guide piece 147 has a greater magnetic polarization than the matrix 130 under the influence of the orientation magnetic field H _OM , it consists of a magnetically highly saturating material, ie a material that has a high magnetic saturation polarization. For example, the high magnetic saturation material may have a saturation polarization of at least 2.35T. Suitable materials for such a flux guide 147, for example, highly saturating cobalt-iron alloys such as. B. Alloys of the Vacoflux ^® series from Vacuum Schmelze Hanau, Germany. Such materials can also be used for all other flux guide pieces of the present invention. It can apply to all of the flux guide pieces used that their magnetic polarization, which it has under the influence of the orientation magnetic field H _OM , is at least 700 mT greater at a temperature of 20° C. than the magnetic polarization that the matrix 130 has under the influence of the same Orientation magnetic field H _OM has.

If, on the other hand, magnets are to be produced with a high magnetic angular spread D _PM in terms of absolute value or with a strongly pronounced North-South effect W _NS in terms of absolute value, the second relative position can also be selected in such a way that the press hollow or hollows 150, 150' move during the action of the Orientation magnetic field H _OM are in a highly inhomogeneous area of the orientation magnetic field H _OM , as exemplified in the 15A and 15B is shown. As in 15A is shown, the one or more press hollows 150, 150' can be in a symmetrical position between the coil cores 171 and 172 or the orientation magnetic field H _OM . It is the same, however - as exemplified in 15B shown - possible that the one or more press hollows 150, 150 'are clearly outside a symmetrical position between the coil cores 171 and 172 or the orientation magnetic field H _OM . The inhomogeneity of the orientation magnetic field H _OM in the area of the press cavity 150, 150' can be increased by one or more optional flux guide pieces 147 inserted into the die 130, as already explained above.

15C shows a permanent magnet 10, with a basis of 15A explained method was prepared. Correspondingly shows 15D a permanent magnet 10, with a basis of 15B explained method was prepared. The magnetic orientation axis M0 is also shown in each case. Both permanent magnets 10 of 10 have a high magnetic angle spread D _PM or a strong north-south effect.

Optionally, the permanent magnets 10 can each also have two plane-parallel pole faces 101 and 102 . The magnetic orientation axis M0 can run perpendicularly to the pole faces 101 and 102, which is shown in 15C is shown, or it can - as in 15D encloses a first angle γ101 in the range of 0°<γ101<90° or a second angle γ102 in the range of 0°<γ102<90° with the surface normals N101, N102 of the pole faces 101 and 102, respectively. These criteria can be realized not only with permanent magnets 10 that have a north-south effect, but also with those in which the north-south effect is equal or approximately equal to zero.

• Einsetzen unterschiedlich geformter Flussleitstücke in die Matrize beim Pressen der unterschiedlichen Sorten. Einsetzen von Flussleitstücken aus unterschiedlichen Materialien in die Matrize beim Pressen der unterschiedlichen Sorten. Wahl unterschiedlicher Positionen des Presshohls im Orientierungsmagnetfeld während des magnetischen Ausrichtens des in dem Presshohl befindlichen Magnetpulvers beim Pressen der unterschiedlichen Sorten.

The first and second angles γ101 and y102, which can be adjusted during the pressing of the permanent magnet 10 by the position and orientation of the pressing cavity 150, 150' in the orientation magnetic field H _OM and optionally by using one or more flux guide pieces 147, can be greater than , for example 0° or greater than 5°, and/or less than 20° or less than 10°. Permanent magnets 10, in which the first and second angles γ101 and γ102 are greater than 0° and less than 90°, can be used, for. B. use in arrangements, as in relation to the 22 until 24 still to be explained. An advantage of the method is that by selecting the position of one, several or all coil cores 171, 172, 173, 174 (if present) relative to the press cavity or hollows 150, 150', by using one or more magnetic flux conducting pieces 140 to 147, as well as by aligning the one or more press hollows 150, 150', with a press 100 different types of permanent magnets 10 can be produced, which have different sized first angles γ101 and/or different sized second angles γ102. This can be achieved, for example, by one or - in any combination - several of the following measures:

• Insertion of differently shaped flux guide pieces in the die when pressing the different grades. Insertion of flux guide pieces made of different materials into the die when pressing the different types. Choosing different positions of the press cavity in the orientation magnetic field during the magnetic alignment of the magnetic powder in the press cavity when pressing the different types.

des Orientierungsmagnetfeldes H_OM aufweist, was unter Bezugnahme auf 15E veranschaulicht wird. 15E zeigt eine Draufsicht auf die Einfüllöffnung 131 der Matrize 130, sowie die mittlere Querrichtung $\langle {\stackrel{\rightharpoonup }{R}}_q\rangle$

der (im Allgemeinen lokal veränderlichen) Querkomponenten ${\stackrel{\rightharpoonup }{H}}_q$

des Orientierungsmagnetfeldes H_OM. Parallel zu dieser mittleren Querrichtung $\langle {\stackrel{\rightharpoonup }{R}}_q\rangle$

weist die Einfüllöffnung 131 verschiedene Öffnungsweiten s auf. Der arithmetische Mittelwert 〈s〉 all dieser Öffnungsweiten s stellt das Vorzugsrichtungsmaß des Grünlings dar.On the basis of 13A , 13B , 14 and 15A until 15D In the manner explained, any powder-pressed permanent magnet can be produced in principle, as long as the desired magnet shape can be produced with just one punch 110 or 120, which acts against a fixed die 130, or with two punches 110, 120 acting against each other, i.e. with a so-called "single-stage" Press. A particular advantage of this process is that magnets with a high aspect ratio can also be produced. For example, the aspect ratio of the height of the green body (=extension area of the pressed green body parallel to the direction of pressing) to the dimension of the preferred direction (for definition see below) can be at least 2.5÷1 or even at least 3.5÷1. Thereby can the preferred direction dimension can optionally be less than or equal to 10 mm or even less than or equal to 5 mm. By sintering the green body into a permanent magnet, the aspect ratio increases due to anisotropic shrinkage. Accordingly, after sintering (ie before any subsequent machining), a green compact may have an aspect ratio of at least 2.9÷1 or even at least 4.0÷1, with the height of the green compact sintered to the magnet again being parallel to the direction of the green compact is to be determined in which the green compact was pressed. The preferred direction of the magnet can, for example, be less than 8 mm or even less than 4 mm. Here, the preferred direction dimension of the green compact is defined by the arithmetic mean value 〈s〉 of the opening widths s, which the filling opening 131 in the direction of which will be referred to later 20 explained mean transverse direction $〈{\stackrel{\rightharpoonup }{R}}_q〉$

of the orientation magnetic field H _OM , which can be seen with reference to FIG 15E is illustrated. 15E shows a top view of the filling opening 131 of the die 130, as well as the central transverse direction $〈{\stackrel{\rightharpoonup }{R}}_q〉$

of the (generally locally variable) transverse components ${\stackrel{\rightharpoonup }{H}}_q$

of the orientation magnetic field H _OM . Parallel to this mean transverse direction $〈{\stackrel{\rightharpoonup }{R}}_q〉$

the filling opening 131 has different opening widths s. The arithmetic mean 〈s〉 of all these opening widths s represents the preferred direction of the green body.

zu ermitteln, und zwar als arithmetischer Mittelwert der Breiten, die der aus dem Grünling entstandene Sintermagnet parallel zu dieser Richtung aufweist.After sintering and before any subsequent mechanical processing, the preferred direction dimension is in the same central transverse direction in relation to the green body $〈{\stackrel{\rightharpoonup }{R}}_q〉$

to be determined as the arithmetic mean of the widths that the sintered magnet formed from the green compact has parallel to this direction.

The magnets can be produced without the finished, sintered green compacts being cut up again in order to obtain (then smaller) magnets with a high aspect ratio. Magnets with a high aspect ratio can therefore be produced directly by pressing the magnetic powder and subsequent sintering without subsequent mechanical fragmentation. The problem with the production of magnets with a high aspect ratio is that the pressed hollows 150, 150' must then also have a high aspect ratio, which makes it difficult to fill the pressed hollows 150, 150' with the magnetic powder 200.

In principle, the orientation magnetic field H _OM can be oriented as desired and depending on the type of magnet to be produced. If a magnet pressed in the so-called “transverse field” is to be produced, the coil arrangement 161, 162 can have a coil axis which, at least in the second relative position, runs perpendicularly or essentially perpendicularly to the pressing direction.

The present invention enables, among other things, the production of first a first pressed permanent magnet and then a second pressed permanent magnet, which have different angles γ101 and γ102, using the same die 130 and the same coil arrangement 161, 162. Otherwise, any method for filling, used for magnetically aligning the magnetic powder filled into the press cavity or hollows and for pressing the filled magnetic powder. What is decisive is that during the manufacture of the first and second permanent magnets, the orientation magnetic fields H _OM present within the press cavity differ in terms of their orientation and/or strength. For this purpose, the different orientation magnetic fields H _OM within the press cavity can in principle be achieved by any measures.

A first measure can be that the second relative position when manufacturing the first permanent magnet is different from the second relative position when manufacturing the second permanent magnet.

A second measure can be that the orientation magnetic field H _OM differs _from the orientation magnetic field H OM when manufacturing the second permanent magnet in terms of its strength and/or its course when the first permanent magnet is manufactured.

A third measure can consist in inserting a first flux conducting piece into the die 130 during the manufacture of the first permanent magnet, whereas no flux conducting piece is inserted into the die 130 at the location of the first flux conducting piece during the manufacture of the second permanent magnet, or else a different one , Second flux conducting piece, which differs from the first flux conducting piece in terms of its geometry and/or in terms of its magnetic saturation polarization.

A fourth measure can consist in using a first press ram 110 to press the first permanent magnet and a second press ram 110 to produce the second permanent magnet, with the first press ram 110 differing from the second press ram in terms of its geometry and/or in terms of its magnetic saturation polarization 110 differs.

The measures mentioned can be applied individually or in any combination with two or more of the measures mentioned.

As already mentioned, the invention thus enables the successive production of a first and then a second permanent magnet with different first angles γ101 using the same press 100 or the same press parts (e.g. the same press cavity, the same die, the same upper punch, the same lower punch, the same coil arrangement , or any combination thereof). In principle, the angle difference between the first angles γ101 of the first and second permanent magnet is arbitrary (>0°), it can be at least 5° or at least 10°, for example.

Optionally, the first and second permanent magnets can also have different second angles γ102. In principle, the angle difference between the second angles γ102 of the first and second permanent magnet is arbitrary (>0°), it can be at least 5° or at least 10°, for example.

The following are based on the 16 until 19 various exemplary embodiments for filling funnels 210 for filling a magnetic powder into a press cavity 150 or into two press cavities 150, 150' are shown.

The 16 and 17 each show a hopper 210. Below that, a press cavity 150 to be filled with a magnetic powder via the hopper 210 is shown schematically. On its underside facing the pressing cavity 150 , the filling hopper 210 has an outlet opening 211 through which a magnetic powder located in the filling hopper 210 can be introduced into the pressing cavity 150 . Starting from the outlet opening 211, the hopper 210 has a first wall section 221 which extends parallel to the pressing direction z over a height b221 and which encloses an angle φ with a plane E perpendicular to the pressing direction z. The angle φ can vary over the wall section 221 or it can be constant. A second wall section 222 adjoins the side of the first wall section 221 facing away from the press cavity 150 . The height of the hopper 210 in the pressing direction z is denoted by h210 in each case.

The same applies to each of the 18 and 19 hopper 210 shown, with the difference that the hopper 210 is used for the simultaneous filling of two press hollows 150 and 150' that are spaced apart perpendicularly to the pressing direction z. For this purpose, the hopper 210 has a first outlet opening 211 for filling the first compression cavity 150, and a second outlet opening 211', spaced apart from the first outlet opening 211, for filling the second compression cavity 150'. In each of the hoppers 210, the first outlet opening 211 may have the same opening width b211 and the same opening shape as the second outlet opening 211'. Parallel to the pressing direction z, the first wall section 221 extends over two thirds of the height h210 of the hopper 210.

The hopper 210 of 16 and 18 are used to fill press cavities 150 or 150', which have a large press cavity width b150 or b150', for example at least 7 mm. In this case, the angle φ can be 50°, for example. In addition, the first inlet opening 211 and, if applicable, the second inlet opening 211' can have an opening width w211 or w211' in a sectional plane parallel to the pressing direction z, which is smaller, for example by 1 mm, than the pressing cavity width b150 or b150' of the relevant Inlet opening 211 or 211 'filled press hollow 150 or 150'. The hopper 210 can, in the area of its outlet opening 211 or 211' belonging to the pressing cavity 150 or 150' in question, extend the inlet opening 211 or 211 of the pressing cavity 150 or 150' below at its outer edge by a certain distance d211 or d211', for example 0.5 mm, circumferentially along the outer edge of the inlet opening 211 or 211'.

The hopper 210 of 17 and 19 on the other hand, are used for filling press cavities 150 or 150 and 150', which have a small press cavity width b150 or b150', for example less than 7 mm. In this case, the angle φ can be 70° or even more than 70°, for example. In addition, the first inlet opening 211 and, if applicable, the second inlet opening 211' can have an opening width w211 or w211' in a sectional plane parallel to the pressing direction z, which is equal to the pressing cavity width b150 or b150' of the inlet opening 211 or 211' in question press hollow 150 or 150'.

in Axial- oder Pressrichtung z und eine Komponente ${\stackrel{\rightharpoonup }{H}}_q$

quer (d.h. senkrecht) zur Pressrichtung z, wobei die Komponenten ${\stackrel{\rightharpoonup }{H}}_q$

an verschiedenen Stellen des Presshohls im Allgemeinen in verschiedenen zur Pressrichtung z jeweils senkrechten Richtungen verlaufen. Für jede der Komponenten $\left|{\stackrel{\rightharpoonup }{H}}_z\right|\text{ und }{\stackrel{\rightharpoonup }{H}}_q$

lässt sich nun ein Mittelwert $\langle \left|{\stackrel{\rightharpoonup }{H}}_z\right|\rangle$

der Absolut-Beträge $\left|{\stackrel{\rightharpoonup }{H}}_z\right|\text{ von }{\stackrel{\rightharpoonup }{H}}_z$

bzw. ein Mittelwert $\langle \left|{\stackrel{\rightharpoonup }{H}}_q\right|\rangle$

der Absolut-Beträge $\left|{\stackrel{\rightharpoonup }{H}}_q\right|\text{ von }{\stackrel{\rightharpoonup }{H}}_q$

bestimmen.With the present invention, a magnetic powder 200 can be pressed not only in the “axial field” but also in the “transverse field”. Based on 20 is shown using an enlarged section of 15A explains what is to be understood by "pressing in the axial field" or by "pressing in the transverse field" within the meaning of the present invention. In principle, the orientation magnetic field H _OM can be broken down into exactly two components at each point Q in the volume area of the press cavity 150, namely into one component ${\stackrel{\rightharpoonup }{H}}_{\mathrm{e.g}}$

in the axial or pressing direction z and one component ${\stackrel{\rightharpoonup }{H}}_q$

across (ie perpendicular) to the pressing direction z, where the components ${\stackrel{\rightharpoonup }{H}}_q$

generally run in different directions perpendicular to the pressing direction z at different points of the pressing cavity. For each of the components $\left|{\stackrel{\rightharpoonup }{H}}_{\mathrm{e.g}}\right|\text{and}{\stackrel{\rightharpoonup }{H}}_q$

can now be an average $〈\left|{\stackrel{\rightharpoonup }{H}}_{\mathrm{e.g}}\right|〉$

the absolute amounts $\left|{\stackrel{\rightharpoonup }{H}}_{\mathrm{e.g}}\right|\text{from}{\stackrel{\rightharpoonup }{H}}_{\mathrm{e.g}}$

or an average $〈\left|{\stackrel{\rightharpoonup }{H}}_q\right|〉$

the absolute amounts $\left|{\stackrel{\rightharpoonup }{H}}_q\right|\text{from}{\stackrel{\rightharpoonup }{H}}_q$

determine.

größer ist als 1.As "pressing in the axial field" is understood in the sense of the present invention when the ratio $〈\left|{\stackrel{\rightharpoonup }{H}}_{\mathrm{e.g}}\right|〉÷〈\left|{\stackrel{\rightharpoonup }{H}}_q\right|〉$

is greater than 1.

größer ist als 1.Correspondingly, “cross field pressing” is understood to mean that the ratio when the ratio $〈\left|{\stackrel{\rightharpoonup }{H}}_q\right|〉÷〈\left|{\stackrel{\rightharpoonup }{H}}_{\mathrm{e.g}}\right|〉$

is greater than 1.

In all variants of the invention, the pressing can take place both in the longitudinal field and in the transverse field, provided that a corresponding course of the orientation magnetic field H _OM is set.

definiert. Bei der mittleren Querrichtung $\langle {\stackrel{\rightharpoonup }{R}}_q\rangle$

handelt es sich um die gemittelten Richtungen der (im Allgemeinen lokal veränderlichen) Querkomponenten ${\stackrel{\rightharpoonup }{H}}_q$

des Orientierungsmagnetfeldes H_OM, wobei die Mittelung wiederum über den Volumenbereich des Presshohls 150 erfolgt.Also based on 20 becomes the mean transverse direction already mentioned $〈{\stackrel{\rightharpoonup }{R}}_q〉$

Are defined. At the middle transverse direction $〈{\stackrel{\rightharpoonup }{R}}_q〉$

are the averaged directions of the (generally locally variable) transverse components ${\stackrel{\rightharpoonup }{H}}_q$

of the orientation magnetic field H _OM , with the averaging again taking place over the volume area of the press cavity 150 .

Magnets 10, 20, which have a high angular spread and/or a strong north-south effect, can be used in a motor or in a rotor 1 as already referred to in FIG 1 was explained. An example of this shows 21 . The magnets 10, 20, which can each have a magnetic angular spread D _PM , the amount of which is greater than 20° or even greater than 30°, and which have a north-south effect, are arranged in the rotor 1 in such a way that their hot sides each face the air gap 12 or are directed outwards in the radial direction of the rotor 1 . As a result, north poles and south poles are arranged alternately one after the other along the circumference of the rotor 1, each of these north and south poles being formed by the hot side of one of the magnets 10, 20. At least one, several or each of the magnets 10, 20 can have been produced by means of one of the methods explained above. In particular, each of these magnets 10, 20 can be used without changing its geometric shape after the pressing and sintering of the magnetic powder 200 on which it is based, e.g. B. by mechanical processing such as sawing, abrasive cutting, water jet cutting, laser cutting, etc., is divided into several parts. In addition, subsequent cleaning of the surface, for example by sandblasting or pickling, as well as grinding or calibration grinding of the surfaces is possible, in particular the pole faces, in order to reduce any dimensional tolerances. For the purposes of the present invention, such surface treatments are not considered mechanical dissection of the magnet.

In addition, each of these magnets 10, 20 is formed in one piece, i. H. it is not composed of two or more separately manufactured partial magnets which are then glued together.

As per the example 21 As can be seen, each of the north poles and south poles arranged alternately in succession along the circumference of the rotor 1 can be formed by exactly one of the magnets 10 and 20, respectively. In contrast, based on 22A until 22C , 23A until 23C and 24 a motor having a rotor 1 is explained, in which each of the north poles and south poles arranged alternately in succession along the circumference of the rotor 1 is formed by two magnets 10 and 20, respectively.

22A 10 shows two magnets 10 ₁ and 10 ₂ each having a magnetic orientation axis a10 ₁ and a10 ₂ , respectively. The two magnets 10 ₁ and 10 ₂ can, as in 22B is shown, are arranged next to each other at a small distance d10. In particular, the magnets 10 ₁ and 10 ₂ can also lie directly next to one another, ie the distance d10 is equal to zero in this case, which in 22C is shown. In each of these magnet arrangements, the directions (each from south to north) of the magnetic orientation axes a10 ₁ and a10 ₂ can enclose an angle α which is greater than 0° and less than 120°, or which is greater than 10° and less than 120°. If the two magnetic orientation axes a10 ₁ and a10 ₂ do not run parallel to one another, their directions enclose an angle α. This applies both when the magnetic orientation axes a10 ₁ and a10 ₂ intersect and when they are skewed to one another. If they intersect, the relevant point of intersection is on the north pole side of each of the magnets 10 ₁ and 10 ₂ . Otherwise, if the magnetic orientation axes a10 ₁ and a10 ₂ are skewed to one another, there is exactly one connecting path between them, the length of which corresponds to the (smallest) distance between the magnetic orientation axes a10 ₁ and a10 ₂ . This link is located then north pole side of each of the magnets 10 ₁ and 10 ₂ .

Correspondingly shows 23A two magnets 20 ₁ and 20 ₂ each having a magnetic orientation axis a20 ₁ and a20 ₂ , respectively. The two magnets 20 ₁ and 20 ₂ can, as in 23B is shown, are arranged next to each other at a small distance d20. In particular, the magnets 20 ₁ and 20 ₂ can also lie directly next to one another, ie the distance d20 is equal to zero in this case, which in 23C is shown. In each of these magnet arrangements 23B and 23C the directions of the magnetic orientation axes a20 ₁ and a20 ₂ can enclose an angle α which is greater than 0° and smaller than 120° or which is greater than 10° and smaller than 120°. If the two magnetic orientation axes a20 ₁ and a20 ₂ do not run parallel to one another, their directions enclose an angle β. This applies both when the magnetic orientation axes a20 ₁ and a20 ₂ intersect and when they are skewed to one another. If they intersect, the relevant point of intersection is on the south pole side of each of the magnets 20 ₁ and 20 ₂ . Otherwise, if the magnetic orientation axes a20 ₁ and a20 ₂ are skewed to one another, there is exactly one connecting path between them, the length of which corresponds to the (smallest) distance between the magnetic orientation axes a20 ₁ and a20 ₂ . This connecting section then lies on the south pole side of each of the magnets 20 ₁ and 20 ₂ .

The angles α and β explained above are each given by the smaller of the two angles between the respective north directions (tips of the black arrows) of the magnetic orientation axes a20 ₁ and a20 ₂ . For example, the north directions of the magnetic orientation axes a20 ₁ and a20 ₂ in den 22B , 22C , 23B and 23C an angle of 40° but also an angle of 320°. The smaller value, namely 40°, should be selected for the angles α and β.

According to the 22A , 22B , 22C , 23A , 23B , 23C and 24 For example, each of the north and south poles arranged alternately one after the other along the circumference of the rotor 1 can also be formed from more than two individual permanent magnets, each of which has been produced according to one of the methods explained above. Optionally, each of these permanent magnets can be used in the rotor 1 after the pressing and sintering of the underlying magnetic powder without its geometric shape being changed by dividing or separating after the pressing and sintering.

Through the use of permanent magnets 10, 20, 10 ₁ , 20 ₁ , 10 ₂ , 20 ₂ with a high magnetic angular spread D _PM and/or with a high North-South effect W _NS in a rotor 1, an air gap 12 achieve a high spatial concentration of the magnetic flux between the rotor 1 and a stator 2 of the motor. Such a rotor 1 can be used not only in a motor but also in a generator.

Claims (28)

A method for producing at least two pressed permanent magnets from a magnet powder (200), comprising the steps of: providing a press (100) which has a die (130) with a first press cavity (150) and a second press cavity (150'), and one first ram (110) and a second ram (110'), each of which can be adjusted in a pressing direction (z) relative to the die (130); providing a magnetic powder (200); providing a coil assembly (161, 162); Filling the magnetic powder (200) into the first pressing cavity (150) and into the second pressing cavity (150') with the aid of a filling magnetic field which is generated with the coil arrangement (161, 162) while the coil arrangement (161, 162) is moving with respect to the die (130) is in a first relative position; Aligning the magnetic orientation of the magnetic powder (200) filled into the pressing cavity (150, 150') with the aid of an orientation magnetic field (H _OM ) which is generated with the coil arrangement (161, 162) while the coil arrangement (161, 162) is relative to the die (130) is in a second relative position different from the first relative position; Simultaneous pressing of the magnetic powder (200) filled into the pressing cavity (150, 150') and aligned with the aid of the orientation magnetic field (H _OM ) by - a part of the magnetic powder (200) located in the first pressing cavity (150) by the action of the first pressing ram (110) compressing each resulting in a first green compact and sintering the first green compact into a first powder-compacted permanent magnet; and - a part of the magnet powder (200) located in the second press cavity (150') is compressed by the action of the second press die (110) to produce a second green body and the second green body is sintered to form a second powder-pressed permanent magnet. procedure after claim 1 , in which the orientation magnetic field (H _OM ) in the first press cavity (150) filled magnetic powder (200) within the volume range of first compression cavity (150) and/or within the volume region of the part of the magnetic powder (200) filled into the first compression cavity (150) at least temporarily has a field strength of at least 400 kA/m; and/or when the magnetic powder (200) is filled into the second press cavity (150') within the volume area of the second press cavity (150') and/or within the volume area of the part of the magnetic powder (200) filled into the second press cavity (150') at least temporarily has a field strength of at least 400 kA/m. procedure after claim 1 or 2 wherein each of the green compacts after pressing and before sintering has an aspect ratio of at least 2.5÷1 or at least 3.5÷1. Procedure according to one of Claims 1 until 3 , in which each of the pressing cavities (150, 150') perpendicular to the pressing direction (z) has an inner width of less than or equal to 10 mm or less than or equal to 5 mm. Procedure according to one of Claims 1 until 4 , In which the coil arrangement (161, 162) has a coil axis which runs perpendicularly to the pressing direction (z) at least in the second relative position. Procedure according to one of Claims 1 until 5 , in which the orientation magnetic field (H _OM ) within the pressing cavity (150, 150') has a mean absolute axial component at least in the second relative position in the pressing direction (z). $\left(〈\left|{\stackrel{\rightharpoonup }{H}}_{\mathrm{e.g}}\right|〉\right)$

has, and transverse to the pressing direction (z) an average absolute transverse component $\left(〈\left|{\stackrel{\rightharpoonup }{H}}_q\right|〉\right),$

where the ratio $(〈\left|{\stackrel{\rightharpoonup }{H}}_q\right|〉÷\left(〈\left|{\stackrel{\rightharpoonup }{H}}_G\right|〉\right)$

between the mean absolute transverse component $\left(〈\left|{\stackrel{\rightharpoonup }{H}}_q\right|〉\right)$

and the mean absolute axial component $\left(〈\left|{\stackrel{\rightharpoonup }{H}}_{\mathrm{e.g}}\right|〉\right)$

is greater than 1. Procedure according to one of Claims 1 until 6 , in which the first permanent magnet and the second permanent magnet each have a first pole face (101) with a surface normal (N101) and a magnetic orientation axis (M0) which encloses an angle (γ101) with the surface normal (N101) of the relevant permanent magnet, whose absolute value is less than 1°; or approximately equal to 0°. Procedure according to one of Claims 1 until 7 wherein the die (130) has a filling opening (131, 131') for each of the pressing cavities (150, 150') through which the magnetic powder (200) is filled into the relevant pressing cavity (150, 150'); and the first relative position is selected in such a way that the point of the filling magnetic field at which it causes a maximum filling force on the magnetic powder (200) in terms of amount in the pressing direction (z) is in the pressing direction (z) at the level of one of the filling openings (131, 131'). Procedure according to one of Claims 1 until 8th with a first flux conducting piece (142) and a second flux conducting piece (143) spaced apart from the first flux conducting piece (142), each of which has a greater magnetic polarization than the matrix (130) under the influence of the orientation magnetic field (H _OM ), the first Flow guide piece (142) has a first end section (142e) on its side facing the second flow guide piece (143); the second flux guide piece (143) has a second end section (143e) on its side facing the first flux guide piece (142); the first end section (142e) and the second end section (143e) are each arranged between the first pressing cavity (150) and the second pressing cavity (150'). procedure after claim 9 , in which the first flux-conducting piece (142) has a magnetic polarization under the influence of the orientation magnetic field (H _OM ) which is greater than the magnetic polarization which the matrix has under the influence of the orientation magnetic field (H _OM ); and/or the second flux guide piece (143) has a magnetic polarization under the influence of the orientation magnetic field (H _OM ) that is greater than the magnetic polarization that the matrix (130) has under the influence of the orientation magnetic field (H _OM ). procedure after claim 9 or 10 wherein the first end portion (142e) forms part of the wall of the first die cavity (150) and part of the wall of the second die cavity (150'); and the second end portion (143e) forms part of the wall of the first die cavity (150) and part of the wall of the second die cavity (150'). Procedure according to one of Claims 1 until 11 with a third flux guide piece (147), which is arranged between the first press cavity (150) and the second press cavity (150') in the die (130) and which, under the influence of the orientation magnetic field (H _OM ), has a greater magnetic polarization than that die (130). procedure after claim 12 , In which the third flux guide (147) under the influence of the orientation magnetic field (H _OM ) a magnetic Having polarization which is greater than the magnetic polarization exhibited by the matrix (130) under the influence of the orienting magnetic field (H _OM ). procedure after claim 12 until 13 , in which the third flow guide piece (147) extends in the pressing direction (z) at least over the length of the first pressing cavity (150) and the length of the second pressing cavity (150 '). Procedure according to one of Claims 1 until 14 , wherein the first press cavity (150) and the second press cavity (150') are arranged mirror-symmetrically to one another in the die (130) with respect to a first plane of symmetry (SE1) and have mirror-symmetrical shapes to the first plane of symmetry (SE1). procedure after claim 15 , in which in the first relative position the profile of the filling magnetic field during the entire filling process within the first compression cavity (150) with respect to the first plane of symmetry (SE1) is continuously mirror-symmetrical to its profile within the second compression cavity (150 '). procedure after claim 15 or 16 , in which in the second relative position the profile of the orientation magnetic field (H _OM ) within the first press cavity (150) is mirror-symmetrical with respect to the first plane of symmetry (SE1) to the profile of the orientation magnetic field (H _OM ) within the second press cavity (150 '). Procedure according to one of Claims 15 until 17 , in which the course of the orientation magnetic field (H _OM ) within the first press cavity (150) with respect to the first plane of symmetry (SE1) from a first point in time to a second point in time is mirror-symmetrical to the course of the orientation magnetic field (H _OM ) inside the second press cavity ( 150'), the first point in time being given by the moment after filling in the magnetic powder at which the two conditions are met simultaneously for the first time, that the coil arrangement (161, 162) is in the second relative position with respect to the matrix (130), and that the orienting magnetic field (H _OM ) is present; and the second point in time is given by the end of the pressing. Procedure according to one of Claims 1 until 18 , in which the press (100) has a third press cavity (150") arranged in the die (130) and a third press ram, and/or a fourth press cavity (150''') arranged in the die (130) and a fourth Press stamp, the magnetic powder (200, 200 ', 200'', 200''') with the help of the filling magnetic field in the third press cavity (150 '') and / or in the fourth press cavity (150 ''') is filled while the coil arrangement (161, 162) is in the first relative position with respect to the die (130), in which the magnetic orientation of the in the first, the second, the third and the fourth press cavity (150, 150', 150'', 150''') filled magnetic powder (200, 200', 200'', 200''') is aligned with the aid of the orientation magnetic field (H _OM ), while the coil arrangement (161, 162) is in the second relative position with respect to the matrix (130). is located; simultaneous pressing of the magnetic powder (200, 200') filled into the first, the second, the third and the fourth pressing cavity (150, 150', 150'', 150''') and aligned with the aid of the orientation magnetic field (H _OM ) , 200'', 200''') so that - a portion (200'') of the aligned magnet powder located in the third die cavity (150'') is compressed by the action of the third die to give a third green compact; and - a portion (200''') of the aligned magnet powder located in the fourth die cavity (150"') is compressed by action of the fourth die to give a fourth green body. procedure after claim 19 , in which the first press cavity (150) and the second press cavity (150') are arranged in the die (130) with mirror symmetry to one another with respect to a first plane of symmetry (SE1) and have mirror-symmetrical shapes with respect to the first plane of symmetry (SE1), and the third press cavity ( 150'') and the fourth press cavity (150''') are arranged in the die (130) with mirror symmetry with respect to the first plane of symmetry (SE1) and have mirror-symmetrical shapes with respect to the first plane of symmetry (SE1); and/or the first press cavity (150) and the third press cavity (150'') are arranged mirror-symmetrically to one another in the die (130) with respect to a second plane of symmetry (SE2) that differs from the first plane of symmetry (SE1) and to the second plane of symmetry (SE2) have mirror-symmetrical shapes, and the second press cavity (150') and the fourth press cavity (150''') are arranged mirror-symmetrical to each other in the die (130) with respect to the second plane of symmetry (SE2) and have mirror-symmetrical shapes to the second plane of symmetry (SE2). procedure after claim 20 , in which in the first relative position the profile of the filling magnetic field during the entire filling process with respect to the first plane of symmetry (SE1) within the first press cavity (150) is mirror-symmetrical to its profile within the second press cavity (150'); and or inside the third compression cavity (150'') is mirror-symmetrical to its course inside the fourth compression cavity (150'''). procedure after claim 20 or 21 in which in the first relative position the course of the filling magnetic field during the entire filling process with respect to the second plane of symmetry (SE2) within the first press cavity (150) is mirror-symmetrical to its course within the third press cavity (150''); and/or within the second compression cavity (150') is mirror-symmetrical to its course within the fourth compression cavity (150'''). Procedure according to one of claims 20 until 22 , in which, in the second relative position, the profile of the orientation magnetic field (H _OM ) with respect to the first plane of symmetry (SE1) within the first press cavity (150) is mirror-symmetrical to its profile within the second press cavity (150'); and/or within the third compression cavity (150'') is mirror-symmetrical to its course within the fourth compression cavity (150'''). Procedure according to one of claims 20 until 23 , in which, in the second relative position, the profile of the orientation magnetic field (H _OM ) with respect to the second plane of symmetry (SE2) within the first press cavity (150) is mirror-symmetrical to its profile within the third press cavity (150''); and/or within the second compression cavity (150') is mirror-symmetrical to its course within the fourth compression cavity (150'''). Procedure according to one of claims 20 until 24 in which the first press cavity (150) and the third press cavity (150'') have the same shape and are arranged in the die (130) rotationally symmetrically to one another with respect to a 180° rotation about an axis of rotation (SA); and/or the second press cavity (150') and the fourth press cavity (150''') have the same shape and are arranged in the die (130) rotationally symmetrically with respect to a 180° rotation about the axis of rotation (SA). procedure after Claim 25 , in which, in the second relative position, the course of the orientation magnetic field (H _OM ) within the first press cavity (150) is rotationally symmetrical with respect to a 180° rotation about the axis of rotation (SA) to the course of the orientation magnetic field (H _OM ) inside the third press cavity (150 '''); and/or the profile of the orientation magnetic field (H _OM ) within the second press cavity (150') is rotationally symmetrical with respect to a 180° rotation about the axis of rotation (SA) to the profile of the orientation magnetic field (H _OM ) within the fourth press cavity (150''' ). Procedure according to one of Claims 1 until 26 , in which, in the second relative position, it applies both to the first press cavity (150) and to the second press cavity (150') that the orientation magnetic field (H _OM ) along a straight line section that runs within the relevant press cavity (150) between two the end points (H1, H2) located on the surface of the press cavity (150), has a magnetic angular spread (D _OM ) in a section plane which contains the straight line section, the absolute value of which is greater than 20° or greater than 30°. Procedure according to one of Claims 1 until 26 , in which, in the second relative position, it applies to each of the press cavities (150, 150', 150'', 150''') that for any first point (ST1) within the press cavities (150, 150', 150'') , 150''') and for each second point (ST2) different from the first point (ST1) within the press cavity (150, 150', 150'', 150'''), the following applies: the amount of the orientation magnetic field (H _OM ) at the first location (ST1) is greater than 0.95 times the magnitude of the orientation magnetic field (H _OM ) at the second location (ST2); and the direction of the orienting magnetic field (H _OM ) at the first point (ST1) and the direction of the orienting magnetic field (H _OM ) at the second point (ST2) differ by no more than 5°.

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