JP2004259850A - Annular magnet and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an annular magnet having structure wherein arcuate preforms can be stuck with each other more stiffly and surely. <P>SOLUTION: A cylindrical molding member 1 is formed by a method wherein five radially oriented preforms 2 are combined and end surfaces 3 in arcuate direction of the preforms 2 are stuck with each other. The end surface 3 in arcuate direction of the preform 2 is formed in a surface which is inclined 45° to a radial direction from a surface perpendicular to a circumference direction of the cylindrical molding member 1. Since the surface which is inclined 45° is formed, sticking of the mutual preforms 2 can be performed surely with lower pressurizing force. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a ring-type magnet used for a rotor of a motor or the like, and more particularly to a structure for obtaining a magnet elongated in the axial direction and a manufacturing method thereof.
[0002]
[Prior art]
In general, when forming a radial anisotropic ring magnet often used in a small motor, when forming a magnetic field of a cylindrical magnet that is long in the axial direction, sufficient magnetic field strength cannot be obtained, and the orientation rate of the magnetic powder is low. There is a problem in that the high magnetic characteristics cannot be obtained.
[0003]
In order to solve this problem, for example, a predetermined number of arc-shaped preforms that are oriented in the radial direction and are relatively easy to mold are combined, and both ends of the arc are butted together to apply hydrostatic pressure. It has been proposed to obtain a ring-shaped molded body by performing pressure and obtain an anisotropic ring-type magnet by sintering the ring-shaped molded body (see, for example, Patent Document 1).
[0004]
[Patent Document 1]
Japanese Patent Laid-Open No. 7-161512 (page 2 to page 3, FIG. 2)
[0005]
[Problems to be solved by the invention]
In the conventional radial anisotropic ring magnet, after arc-shaped preforms oriented in the radial direction as described above are subjected to magnetic field orientation molding, a predetermined number of them are combined to fix both end faces of the arc. Because both end faces of the arc to be fixed are perpendicular to the circumferential direction of the arc, it is difficult to apply sufficient pressure at the time of fixing, and the hydrostatic pressure is increased to sufficiently fix the arc. When too much, there was a problem that the preform was damaged.
[0006]
The present invention has been made to solve the above-described problems, and provides a ring magnet having a structure capable of firmly and securely fixing arc-shaped preforms to each other and a method for manufacturing the same. It is intended.
[0007]
[Means for Solving the Problems]
The ring-type magnet according to the present invention uses a plurality of arc-shaped preforms with radial orientation, combines the arc-shaped end faces of the preforms, and fixes the end faces to form a cylinder In the ring-shaped magnet made of a shaped molded body, the fixed end face is a surface inclined with respect to a plane perpendicular to the circumferential direction of the cylindrical shaped body.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
Embodiment 1 FIG.
1 is a perspective view showing a configuration of a cylindrical molded body for manufacturing a ring-type magnet in Embodiment 1 of the present invention, and FIG. 2 shows a preformed body constituting the cylindrical molded body in FIG. It is a perspective view.
[0009]
As shown in FIG. 1, the cylindrical shaped body 1 is formed by combining five preformed bodies 2 oriented in the radial direction and fixing the arc end surfaces 3 of the preformed bodies 2 together. As shown in FIG. 2, each preform 2 has a circular arc end surface 3 inclined by 45 ° with respect to the radial direction from a surface 4 perpendicular to the circumferential direction (arrow direction) of the cylindrical molded body 1. It is made to have.
[0010]
As described above, by applying the end surface 3 of the arc to be fixed to a surface inclined from the surface 4 perpendicular to the circumferential direction of the cylindrical molded body 1, a pressing force for fixing the preforms 2 to each other is obtained. Since it can be made to act strongly with respect to the end surface 3 of the arc to be fixed, the preforms 2 can be firmly fixed to each other with a lower pressure.
[0011]
FIG. 3 is a plan view showing a magnetic field forming method for forming a preform that has been oriented in the radial direction.
[0012]
A powder molding die 5 for magnetic field molding of the preform 2 includes a nonmagnetic body 5c such as stainless steel or a nonmagnetic superhard material, and the powder molding die 5 is made of Nd ₂ Fe ₁₄ B or the like. A cavity 5a having a shape of the preform 2 filled with the magnetic powder material is formed, and a ferromagnetic body 5b made of steel, a super hard material (ferromagnetic body) or the like so as to sandwich an arc of the cavity 5a. Is buried. The end surface in the arc direction of the cavity 5a is formed to have a surface inclined by 45 ° with respect to the radial direction from a plane perpendicular to the circumferential direction of the arc.
[0013]
In addition, a pair of electromagnetic coils 6 is disposed so as to sandwich the powder molding die 5, and the pair of electromagnetic coils 6 generates a parallel magnetic field in a space sandwiching the powder molding die 5, and the generated parallel magnetic field is ferromagnetic. The radial direction (broken line arrow) of the arcuate cavity 5a is formed by the body 5b.
[0014]
The magnetic powder material is filled in the cavity 5a of the powder molding die 5, and a magnetic field of 1.5T, for example, is generated by the electromagnetic coil 6, and the magnetic powder material is oriented in the radial direction in this magnetic field, The arc-shaped preform 2 shown in FIG. 2 is obtained by compression molding at a pressure of 10 to 20 MPa using the nonmagnetic upper and lower punches 5d.
[0015]
FIG. 4 is a plan view (a) and a cross-sectional view (b) showing a fixing method for combining and fixing the obtained preforms to obtain a cylindrical molded body.
[0016]
As shown in FIG. 4, the mold 7 includes a die 7a made of metal, a rubber-like pressurizing core 7d inserted into the die 7a, and an upper punch for restraining the preform 2 from above and below. 7b and lower punch 7c.
[0017]
The inner diameter of the die 7a is 0.01 to 0.1 mm larger than the outer diameter when the preform 2 is combined in a ring shape, and the cross-sectional shape and diameter of the upper and lower punches 7b and 7c are the same as the ring of the preform 2 The outer diameter of the pressing core 7d is made 0.01 to 0.1 mm smaller than the inner diameter when the preform 2 is combined in a ring shape.
[0018]
The lower punch 7c is inserted into the die 7a, and five preforms 2 are combined and inserted into the die 7a on which the lower punch 7c is set. Next, the upper punch 7b and the pressing core 7d are inserted, the vertical direction of the preform 2 is constrained by the upper punch 7b and the lower punch 7c, and an axial compression pressure is applied to the pressing core 7d to apply pressure. By expanding the pressure core 7d in the radial direction, a pressure of 50 to 100 MPa is applied to the wall surface of the preform 2.
[0019]
By making the inner diameter of the die 7a 0.01 mm or more larger than the outer diameter when the preformed body 2 is combined in a ring shape, the preformed body 2 can be easily inserted in combination. The pressure core 7d can be easily inserted into the inserted ring-shaped preform 2 by making it smaller than the inner diameter of the preform 2 combined with the outer diameter of 7d by 0.01 mm or more.
[0020]
Also, the inner diameter of the die 7a is made larger than the outer diameter when the preform 2 is combined in a ring shape so as to exceed 0.1 mm, and the inner diameter of the preform 2 combined with the outer diameter of the pressing core 7d. However, if it is made smaller than 0.1 mm, it is difficult to transmit the pressing force of the pressing core 7d to the combined preform 2.
[0021]
Since the end surface 3 of the preliminarily molded body 2 to be fixed is a surface inclined by 45 ° with respect to the radial direction from a plane perpendicular to the circumferential direction of the arc (circumferential direction of the cylindrical molded body), the applied pressure is It can be made to act strongly with respect to the end face 3 to adhere, and the preformed bodies 2 can be firmly secured to each other with a lower applied pressure.
[0022]
After the preformed body 2 is integrated by fixing, the cylindrical shaped body is taken out from the mold 7, and the taken out cylindrical shaped body 1 is sintered and heat-treated to obtain a radially oriented ring magnet. For example, when Nd ₂ Fe ₁₄ B is used as the magnetic powder material, sintering is performed at about 1080 ° C., and an aging treatment at 550 to 900 ° C. is applied.
[0023]
In addition, although the case where the end surface 3 of the preform 2 is a surface inclined by 45 ° with respect to the radial direction from a surface perpendicular to the circumferential direction of the circular arc is not limited to 45 °, the preliminary surface to be fixed is fixed. If the end surface 3 of the molded body 2 is a surface inclined with respect to the radial direction from a surface perpendicular to the circumferential direction of the arc, the effect in this embodiment is obtained.
[0024]
Further, the compression pressure when the preform 2 is fixed in combination varies depending on the size of the ring magnet to be manufactured.
[0025]
Further, as shown in a plan view (a) and a partially enlarged plan view (b) of FIG. 5, the angle formed in the radial cross section of the cylindrical molded body 1 between the end surface and the peripheral surface is an acute edge. By providing the chamfered portion or the R-attached portion 3a and providing the obtuse-angled edge with the chamfered portion or the R-attached portion 3a, it is possible to prevent the edge from being chipped or broken.
[0026]
Further, as shown in the plan view of FIG. 6, by providing the end surface 3 of the preform 2 with the unevenness 3b of about 0.01 mm to 0.5 mm, the fixing area is increased, and the fine unevenness is slightly crushed. As the irregularities become compatible, the fixing force increases.
[0027]
If the unevenness is smaller than 0.01 mm, the effect is not obtained, and if the unevenness is larger than 0.5 mm, the unevenness is not adapted, stress concentration occurs locally, and the combined preform 2 is damaged. To do.
[0028]
Embodiment 2. FIG.
FIG. 7 is a perspective view showing a configuration of a cylindrical molded body according to Embodiment 2 of the present invention. In the figure, the same reference numerals as those in the first embodiment indicate the same or corresponding parts.
[0029]
As shown in FIG. 7, the end surface 3 to which the arc-shaped preform 2 is fixed is inclined with respect to the axial direction of the cylindrical molded body 1 from a surface perpendicular to the circumferential direction of the cylindrical molded body 1. .
[0030]
FIG. 8 is a cross-sectional view showing a magnetic field forming method for forming a preform that has been subjected to orientation treatment in the radial direction.
[0031]
As shown in FIG. 8 (a), a powder molding die for magnetic field molding is made up of a nonmagnetic body 5c such as stainless steel or a nonmagnetic cemented carbide material and a ferromagnetic body 5b embedded in the nonmagnetic body 5c. comprising die and, upper punch 5d made of a nonmagnetic material 5c embedded in the tip sides of the lower punch 5d and ferromagnetic body made of ferromagnetic material thus spare magnetic powder material consisting of Nd 2 _Fe 14 _B or the like is filled A cavity 5a in the shape of a molded body is formed. In addition, an electromagnetic coil 6 that generates a magnetic field in the pressing direction of the upper and lower punches 5d is disposed. The ferromagnetic body 5b embedded in the nonmagnetic body 5c and the nonmagnetic body 5c embedded on both sides of the top end of the upper punch 5d are formed so that the generated magnetic flux faces the radial direction of the cavity 5a.
[0032]
The shape of the cavity 5a viewed from above in FIG. 8 (a) is such that the end face 5e in the arc direction is inclined with respect to the axial direction, as shown in FIG. 8 (b).
[0033]
The magnetic powder material for molding the preform is filled in the cavity 5a of the powder molding die 5, and a magnetic field of 1.5T, for example, is generated by the electromagnetic coil 6, and the magnetic powder material is radial in this magnetic field. The arc-shaped preform 2 shown in FIG. 7 is obtained by compression molding at a pressure of 10 MPa to 20 MPa using the upper and lower punches 5d while being oriented in the direction.
[0034]
FIG. 9 is a plan view (a) and a cross-sectional view (b) showing a fixing method for obtaining a cylindrical molded body by combining and fixing a preformed body.
[0035]
As shown in FIG. 9, the mold 7 includes a die 7a made of metal, a rubber-like pressing core 7d inserted into the die 7a, and an upper punch for pressing the preform 2 from above and below. 7b and lower punch 7c.
[0036]
In this embodiment, the lower punch 7c is inserted into the die 7a, and five preforms 2 are combined and inserted into the die 7a on which the lower punch 7c is set. Next, the upper punch 7b and the pressing core 7d are inserted, and the preform 2 is pressed with the upper punch 7b and the lower punch 7c.
[0037]
According to this embodiment, since the end surface 3 of the preformed body 2 to be fixed is a surface inclined with respect to the axial direction from the surface perpendicular to the circumferential direction of the cylindrical molded body 1, the punch 7a, The pressing force in the axial direction by 7b can be made to act strongly on the end face 3 to be fixed, so that the preforms 2 can be firmly fixed to each other with a lower pressing force.
[0038]
In this embodiment, the end surface 3 of the preformed body 2 to be fixed is a surface inclined with respect to the axial direction from the surface perpendicular to the circumferential direction of the cylindrical molded body 1. As in the first embodiment, the end surface 3 is a surface inclined from the surface perpendicular to the circumferential direction of the cylindrical molded body 1 with respect to the radial direction, whereby the applied pressure in the radial direction and the axial direction can be dispersed. As a result, the pressing force required for fixing can be further reduced.
[0039]
In Embodiments 1 and 2, an example in which five preforms 2 are combined has been described, but the number is not limited to this.
[0040]
【The invention's effect】
According to the ring-type magnet according to the present invention, a plurality of arc-shaped preforms with radial orientation are used, end faces in the arc direction of the preforms are combined, and the end faces are fixed to form a cylindrical shape. In the ring-shaped magnet composed of the cylindrical molded body, the fixed end surface is a surface inclined with respect to a plane perpendicular to the circumferential direction of the cylindrical molded body, so that the preliminary molded bodies are more firmly fixed to each other. It can be reliably performed with a low pressure.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a configuration of a ring magnet according to Embodiment 1 of the present invention.
FIG. 2 is a perspective view showing a configuration of a preformed body according to Embodiment 1 of the present invention.
FIG. 3 is a plan view showing a method for magnetic field shaping of a preform in Embodiment 1 of the present invention.
4A and 4B are a plan view and a cross-sectional view showing a fixing method for obtaining a ring-shaped molded body from a preformed body according to Embodiment 1 of the present invention.
5 is a plan view showing the shape of an arcuate end face in the first embodiment. FIG.
FIG. 6 is a plan view showing another shape of the arc-shaped end face in the first embodiment.
FIG. 7 is a perspective view showing a configuration of a ring magnet according to Embodiment 2 of the present invention.
FIG. 8 is a cross-sectional view showing a method for magnetic field shaping of a preform in Embodiment 2 of the present invention.
9A and 9B are a plan view and a cross-sectional view showing a fixing method for obtaining a ring-shaped molded body from a preformed body according to Embodiment 2 of the present invention.
[Explanation of symbols]
1 cylindrical shaped body, 2 preformed body, 3 arc end face, 3a chamfer,
3b Unevenness, 4 Surface perpendicular to the circumferential direction of the arc, 5 Powder molding die,
5a Cavity, 5b Ferromagnetic material, 5c Non-magnetic material,
5d top and bottom punch, 5e end face, 6 electromagnetic coil, 7 mold, 7a die,
7b Upper punch, 7c Lower punch, 7d Pressure core,
13, 17, 22 Cylindrical molded body.

Claims (8)

In a ring-shaped magnet comprising a plurality of arc-shaped preforms with radial orientation, combining the end faces in the arc direction of the preforms, and fixing the end faces to form a cylindrical shape The ring-type magnet is characterized in that the fixed end surface is a surface inclined with respect to a surface perpendicular to the circumferential direction of the cylindrical molded body. 2. The ring magnet according to claim 1, wherein the fixed end surface is a surface inclined with respect to the radial direction of the cylindrical molded body. 2. The ring magnet according to claim 1, wherein the fixed end surface is a surface inclined with respect to the axial direction of the cylindrical molded body. 2. The ring magnet according to claim 1, wherein the fixed end face is a face inclined with respect to the radial direction and the axial direction of the cylindrical molded body. A chamfered portion or an R-attached portion is provided at an acute edge, and a shape portion at which the chamfered portion or the R-attached portion adheres to an obtuse angle edge is provided at an angle formed in the radial section between the fixed end surface and the peripheral surface. The ring magnet according to claim 2 or 4, wherein the ring magnet is formed. The ring magnet according to claim 1, wherein unevenness of 0.01 mm to 0.5 mm is formed on the fixed end face. Using a plurality of arc-shaped preforms with radial orientation,
Combining the preforms, making the plurality of preforms cylindrical, and inserting them into a die of a mold,
Restrain the axial end face of the cylindrical preform with cylindrical upper and lower punches,
Inserting a cylindrical rubber-like pressure core into the cylindrical preform,
By applying axial compressive pressure to the pressurizing core, the pressurizing core is deformed in the radial direction and the wall surface of the cylindrical preform is pressed, thereby forming the cylindrical preform. In the manufacturing method of the ring-type magnet for fixing the end face in the arc direction,
An end face in the arc direction of the preform is formed into a surface inclined in a radial direction with respect to a plane perpendicular to the arc-shaped circumferential direction, and the plurality of preforms are formed into a cylinder by combining the inclined surfaces. And forming
The diameter of the die is 0.01 to 0.1 mm larger than the outer diameter of the cylinder,
The outer diameter and inner diameter of the upper and lower punches are the same as the cylinder,
A method for producing a ring-type magnet, wherein the outer diameter of the pressurizing core is 0.01 to 0.1 mm smaller than the inner diameter of the cylinder. Using a plurality of arc-shaped preforms with radial orientation,
Combining the preforms, making the plurality of preforms cylindrical, and inserting them into a die of a mold,
Restrain the axial end face of the cylindrical preform with cylindrical upper and lower punches,
Inserting a cylindrical rubber-like pressure core into the cylindrical preform,
In the manufacturing method of the ring-shaped magnet that presses and fixes the end face in the arc direction of the cylindrical preform,
An end face in the arc direction of the preform is formed on a surface inclined in an axial direction with respect to a plane perpendicular to the arc-shaped circumferential direction, and the plurality of preforms are formed into a cylinder by combining the inclined surfaces. And forming
A method of manufacturing a ring-type magnet, wherein the upper and lower punches are fixed by pressing the end face in the arc direction.

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