JP5553641B2 - Magnetizing apparatus and method for manufacturing rotating device - Google Patents

Description

The present invention magnetizer, and relates to the production how of the rotating device to use it, to wear磁技surgery particularly by magnetizing apparatus.

  A hard disk drive is known as a medium used for a storage device of a computer. In a hard disk drive, a magnetic recording disk on which recording tracks are formed is rotated at a high speed by a brushless motor. In order to read / write magnetic data contained in the recording track, a magnetic head is disposed on the surface of the magnetic recording disk with a slight gap.

  Generally, a brushless motor has a core around which a coil is wound on the stator side and a cylindrical magnet magnetized by a magnetizing device on the rotor side. When a driving current flows through the coil, a magnetic flux is generated from the core, and this magnetic flux interacts with the magnetic pole of the magnet to generate torque for rotating the brushless motor (see, for example, Patent Document 1).

  As a magnetizing device for magnetizing a magnetic material to be a magnet, for example, a magnetizing device described in Patent Document 2 is known.

JP 2007-198555 A JP 2006-340430 A

Under such circumstances, the present inventor has recognized the following problems.
One way to increase the capacity of a hard disk drive is to reduce the width of the recording track. However, when the hard disk drive vibrates in the in-plane direction of the magnetic recording disk due to, for example, torque ripple, the recording track trace may be disturbed if the recording track width is narrow. If the trace of the recording track is disturbed, a malfunction may occur during data recording / reproduction.

  One of the causes of vibration that occurs during the rotation of the hard disk drive is considered to be the eccentricity of the magnet driving magnetic pole. If this eccentricity is large, the torque ripple is also large, and it is considered that a large vibration occurs. Here, “eccentricity” is, for example, a deviation between the magnetic center of the magnetic poles of the magnet and the rotation axis when the magnet is rotated by being incorporated in a brushless motor.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a technique for reducing the eccentricity of magnetic poles of a magnet.

One embodiment of the present invention relates to a magnetizing apparatus. This magnetizing apparatus is a magnetizing apparatus that magnetizes a cylindrical magnetic body, and a plurality of salient poles that oppose the magnetization target surface of the magnetic body when the magnetic body is attached to the magnetizing apparatus, Including a connecting portion that connects a plurality of salient poles, a portion that is interposed between the plurality of salient poles and the surface to be magnetized, and is bent by attaching a magnetic body, and the positional relationship between the plurality of salient poles and the magnetic body An alignment member to be adjusted.

  According to this aspect, the positional relationship between the plurality of salient poles and the magnetic body can be adjusted by the alignment member.

  Another aspect of the present invention is a method for manufacturing a rotating device. This method includes a step of magnetizing a cylindrical magnetic body using the above magnetizing apparatus and a step of incorporating the magnetized magnetic body as a magnet.

  The “rotating device” may be a device for driving a recording disk, and may be, for example, a brushless motor. Further, the recording disk may be mounted and rotated, and for example, a hard disk drive may be used.

  Note that any combination of the above-described constituent elements, and those obtained by replacing the constituent elements and expressions of the present invention with each other among methods, apparatuses, systems, etc. are also effective as an aspect of the present invention.

  According to the present invention, the eccentricity of the magnetic poles of the magnet can be reduced.

It is a top view which shows a disk drive device. It is the sectional view on the AA line of FIG. FIGS. 3A to 3C are explanatory views for explaining the magnetizing apparatus according to the embodiment. It is sectional drawing corresponding to FIG.3 (b) which shows the state which attached the magnetic body to the magnetization apparatus which concerns on embodiment. It is sectional drawing corresponding to FIG.3 (b) which shows the state which attached the magnetic body to the magnetizing apparatus which concerns on a comparative example. It is a front view which shows the magnetizing apparatus which concerns on a modification. It is CC sectional view taken on the line of FIG.

  The present invention will be described below based on preferred embodiments with reference to the drawings. The same or equivalent components and members shown in the drawings are denoted by the same reference numerals, and repeated descriptions are appropriately omitted. In addition, the dimensions of the members in each drawing are appropriately enlarged or reduced for easy understanding. Also, in the drawings, some of the members that are not important for describing the embodiment are omitted.

In the magnetizing apparatus according to the embodiment, when the magnetic body to be magnetized is mounted so as to face the salient pole of the magnetizing apparatus, the gap between the salient pole and the magnetic body with the alignment member interposed therebetween Level along the circumferential direction. As a result, the degree of eccentricity of the magnetized magnetic pole can be reduced, and vibration derived from the eccentricity can be reduced.
First, a disk drive manufactured by a manufacturing method including a step of magnetizing a cylindrical magnetic body using the magnetizing apparatus according to the embodiment and a step of incorporating the magnetized magnetic body as a cylindrical magnet The apparatus will be described.

(Disk drive)
FIG. 1 is a top view showing the disk drive device 100. FIG. 1 shows a state in which the top cover is removed in order to show the inner configuration of the disk drive device 100. The disk drive device 100 includes a base plate 50, a hub 10, a magnetic recording disk 200, a data read / write unit 8, and a top cover.
Hereinafter, the side on which the hub 10 is mounted with respect to the base plate 50 will be described as the upper side.

  The magnetic recording disk 200 is placed on the hub 10 and rotates as the hub 10 rotates. The base plate 50 is formed by die casting an aluminum alloy. The base plate 50 rotatably supports the hub 10 via a bearing described later. The data read / write unit 8 includes a recording / reproducing head 8a, a swing arm 8b, a pivot assembly 8c, and a voice coil motor 8d. The recording / reproducing head 8a is attached to the tip of the swing arm 8b, records data on the magnetic recording disk 200, and reads data from the magnetic recording disk 200. The pivot assembly 8c supports the swing arm 8b with respect to the base plate 50 so as to be swingable around the head rotation axis. The voice coil motor 8 d swings the swing arm 8 b around the head rotation axis, and moves the recording / reproducing head 8 a to a desired position on the recording surface of the magnetic recording disk 200. The data read / write unit 8 is configured using a known technique for controlling the position of the head.

2 is a cross-sectional view taken along line AA in FIG. The disk drive device 100 is equipped with two 3.5-inch magnetic recording disks 200 having a diameter of 95 mm and rotates them. The diameter of the central hole of each of the two assumed magnetic recording disks 200 is 25 mm and the thickness is 1.27 mm.
The disk drive device 100 includes a substantially cup-shaped hub 10, a shaft 20, a flange 22, a cylindrical magnet 40 that is a cylindrical magnetic body magnetized by the magnetizing device according to the embodiment, and a base plate 50. And a laminated core 60, a coil 70, a sleeve 80, a plate 90, and a lubricant 92.

  The hub 10 is formed in a convex shape with the motor rotation axis R as the center. Hereinafter, a case where two magnetic recording disks 200 are mounted on the hub 10 will be considered. The central hole of the two magnetic recording disks 200 is fitted into the cylindrical outer cylinder surface 10b of the hub 10 protruding upward. The lower magnetic recording disk of the two magnetic recording disks 200 is seated on the seating surface 10c of the surface of the hub 10 projecting in the radial direction from the lower end of the outer cylindrical surface 10b. The diameter of the outer cylinder surface 10b is 25 mm. More precisely, the diameter of the outer cylindrical surface 10b is 24.978 ± 0.01 mm.

  The annular first spacer 202 is inserted between the two magnetic recording disks 200. The clamper 206 presses and fixes the two magnetic recording disks 200 and the first spacer 202 against the hub 10 via the annular second spacer 204. The clamper 206 is fixed to the upper surface 10 a of the hub 10 by a plurality of clamp screws 208.

  A cylindrical magnet 40 is bonded and fixed to the inner peripheral surface 10 d of the hub 10. The cylindrical magnet 40 is made of a rare earth material such as neodymium, iron, or boron, and faces the twelve salient poles of the laminated core 60 in the radial direction. The inner circumferential surface 40a of the cylindrical magnet 40 is magnetized for driving with 8 poles in the circumferential direction. A magnetizing device used for manufacturing the cylindrical magnet 40 will be described later.

  One end of the shaft 20 is fixed to an opening provided in the center of the hub 10 by using both press fitting and adhesion. A flange 22 is press-fitted into the other end of the shaft 20.

  On the upper surface 50a of the base plate 50, a protrusion 52 centered on the motor rotation axis R is provided. The outer peripheral surface of the protrusion 52 is a cylindrical side surface 52 a centering on the motor rotation axis R. A sleeve 80 is bonded and fixed to the inner peripheral surface 52 b of the protruding portion 52. The shaft 20 is accommodated in the sleeve 80. A plate 90 is bonded and fixed to the surface of the sleeve 80 on the flange 22 side.

A lubricant 92 is injected between the shaft 20 and the flange 22 and between the sleeve 80 and the plate 90. The shaft 20, the flange 22, the lubricant 92, the sleeve 80, and the plate 90 constitute a bearing for rotatably supporting the hub 10.
On the inner peripheral surface of the sleeve 80, a pair of herringbone-shaped radial dynamic pressure grooves 82 spaced apart in the vertical direction are formed. A herringbone-shaped first axial dynamic pressure groove 24 is formed on the upper surface of the flange 22, and a herringbone-shaped second axial dynamic pressure groove 26 is formed on the lower surface of the flange 22. When the disk drive device 100 rotates, the hub 10 and the shaft 20 are supported in the radial direction and the axial direction by the dynamic pressure generated in the lubricant 92 by these dynamic pressure grooves.
On the open end side of the sleeve 80, a capillary seal portion 98 is formed, which is a portion where the gap between the inner peripheral surface of the sleeve 80 and the outer peripheral surface of the shaft 20 gradually widens upward. The capillary seal portion 98 prevents the lubricant 92 from leaking out due to a capillary phenomenon.

  The laminated core 60 has an annular portion and 12 salient poles extending outward in the radial direction therefrom. The laminated core 60 is formed by laminating eight thin electromagnetic steel plates and integrating them by caulking. An insulating coating such as electrodeposition coating or powder coating is applied to the surface of the laminated core 60. A coil 70 is wound around each salient pole. When a three-phase substantially sinusoidal drive current flows through the coil 70, a magnetic flux is generated along the salient poles. In the laminated core 60, the inner peripheral surface of the annular portion is press-fitted into the side surface 52a of the protruding portion 52, or is bonded and fixed by clearance fitting.

  The operation of the disk drive device 100 configured as described above will be described. In order to rotate the hub 10 of the disk drive device 100, a three-phase drive current is supplied to the disk drive device 100. When the drive current flows through the coil 70, magnetic flux is generated along the 12 salient poles. Torque is given to the cylindrical magnet 40 by this magnetic flux, and the hub 10 rotates.

Consider the torque ripple in the disk drive device 100. In the disk drive device 100, drive torque is generated by the interaction between the magnetic field generated in the coil 70 and the drive magnetic pole of the cylindrical magnet 40. There is a torque ripple in this driving torque. The frequency of the fundamental wave of torque ripple (hereinafter referred to as the torque ripple center frequency) is determined by assuming that the number of driving magnetic poles of the three-phase disk drive device 100 is P (P is a natural number) and the rotational speed is N (Hz). And is expressed by the following formula 1.
3 · P · N (Hz) (Formula 1)

In reality, there is an interaction non-uniformity that the driving torque acting on the rotor is not uniform over one revolution of the rotor, so the torque ripple is modulated at a frequency equal to the rotational speed N (Hz). Therefore, the torque ripple includes a sideband component having a frequency represented by the following formula 2.
3 · P · N ± N = (3 · P ± 1) · N (Hz) (Formula 2)
For example, in the case of three phases and P = 8 poles, the torque ripple includes a fundamental wave component having a frequency of 24N and a sideband component having a frequency of 24N ± N = (24 ± 1) N. According to the study by the present inventor, it was confirmed that the sideband component increases when the eccentricity of the driving magnetic pole of the cylindrical magnet is large.

  However, in the cylindrical magnet 40 generated using the magnetizing apparatus 300 according to the present embodiment, the eccentricity of the driving magnetic pole is suppressed. Therefore, such a side band component is small in the disk drive device 100 using the cylindrical magnet 40. As a result, the disk drive device 100 with less vibration is realized.

(Magnetizer)
FIGS. 3A to 3C are explanatory diagrams for explaining the magnetizing apparatus 300. FIG. FIG. 3A is a front view showing the magnetizing apparatus 300. FIG. 3B is a cross-sectional view taken along line B-B in FIG. FIG. 3C is a front view showing a state in which the alignment sheet 304 and the attachment member 310 are removed from the magnetizing apparatus 300.
The magnetizing device 300 includes a magnetizing coil 302, four alignment sheets 304, a magnetizing yoke, a magnetizing base 308, and an attachment member 310. The magnetizing device 300 generates a cylindrical magnet 40 by magnetizing a cylindrical magnetic body made of a rare earth material such as neodymium, iron, or boron.

The magnetizing yoke includes a connecting portion 306a and eight magnetizing salient poles 306b corresponding to the number of magnetic poles that extend from the connecting portion 306a in the radial direction and the cylindrical magnet 40 should have, for example, eight poles in the above example. Including. The connecting portion 306a is provided on the magnetized base 308, has a substantially bobbin shape, and connects the eight magnetized salient poles 306b at its body portion. When the magnetic material to be magnetized is attached to the magnetizing device 300, the eight magnetized salient poles 306b are the inner peripheral surface (hereinafter referred to as the inner peripheral surface 40a of the cylindrical magnet 40) that is the magnetic target surface of the magnetic material. The same reference numerals are attached). The eight magnetized salient poles 306b are formed so as to be eight times symmetrical with respect to the symmetry axis S.
As shown in FIG. 3C, the magnetized base 308 has a portion projecting radially outward from the outer diameter of the magnetized salient pole 306b. When a magnetic body to be magnetized is attached to the magnetizing apparatus 300, the magnetic body is fitted from the opposite side, that is, from the upper side of the magnetizing base 308.

  The magnetizing coil 302 is wound around eight magnetized salient poles 306b. The magnetizing coil 302 is wound so that a magnetic flux having a reverse polarity is formed between adjacent magnetized salient poles 306b when a current is passed.

  Each alignment sheet 304 is made of a nonmagnetic elastic material, so that it is nonmagnetic and elastic. As such an elastic material, a material softer than a magnetic material to be magnetized is assumed. Therefore, the alignment sheet 304 is softer than the magnetic material to be magnetized. Such an elastic material is, for example, natural rubber, synthetic rubber, polyimide resin, polyester resin, or any combination thereof.

By making the alignment sheet 304 non-magnetic, it is possible to suppress disturbance in the distribution of the magnetic field when the alignment sheet 304 is magnetized. Since the alignment sheet 304 has elasticity, the alignment sheet 304 bends along the inner peripheral surface 40a of the magnetic body and has a restoring force when the magnetic body to be magnetized is attached to the magnetization apparatus 300. doing. As a result, the possibility of deformation of the magnetic body when the magnetic bodies are fitted together can be reduced, and the magnetic body can be reliably held at a predetermined magnetization position by the restoring force.
As shown in FIG. 3B showing a state before the magnetic body is attached, the left and right side portions of the alignment sheet 304 are separated from the magnetized salient pole 306b and have a gap between the magnetized salient pole 306b. Is forming. Further, as shown in FIG. 4 showing a state in which the magnetic body 400 is attached to the magnetizing device 300 corresponding to FIG. 3B, the alignment sheet 304 is bent along the inner peripheral surface 40a of the magnetic body 400. The left and right side portions of the alignment sheet 304 are bent by the inner peripheral surface 40a so as to approach the magnetized salient pole 306b in the radial direction. That is, in the state of FIG. 3B, the left and right side portions of the alignment sheet 304 are in a radial direction from the cylindrical surface on which the inner peripheral surface 40a of the magnetic body 400 is to be located and opposite to the magnetized salient pole 306b. It sticks out.

When the dynamic friction coefficient of the alignment sheet is large, the resistance due to friction when the magnetic bodies to be magnetized are fitted together increases, and the work efficiency can be reduced.
Correspondingly, each alignment sheet 304 is formed including a material having a dynamic friction coefficient of 0.6 or less. The dynamic friction coefficient of the above polyimide resin or polyester resin is 0.6 or less, which satisfies this condition. As a result, resistance due to friction when fitting magnetic materials to be magnetized is suppressed, and work efficiency is improved. Furthermore, it is more preferable that the alignment sheet 304 includes a material having a dynamic friction coefficient of 0.4 or less.

  When the alignment sheet 304 is formed including a polyester resin, the heat resistance of the alignment sheet 304 is increased, the dynamic friction coefficient is decreased, the flexibility is improved, and the restoring force is easily obtained. Further, when the alignment sheet 304 is formed to include a polyimide resin, the heat resistance is further increased, the dynamic friction coefficient is decreased, the flexibility is improved, and the restoring force is easily obtained.

  Each alignment sheet 304 is formed in a substantially rectangular sheet shape having substantially the same thickness t. The four alignment sheets 304 are interposed between the eight magnetized salient poles 306b and the inner peripheral surface 40a of the magnetic material to be magnetized, and their positional relationship, particularly the gap between the magnetized salient poles 306b and the magnetic material. Adjust. Each alignment sheet 304 has an upper end fixed to the upper portion of the connecting portion 306a by a mounting member 310, and the lower other end being a free movable end. The attachment member 310 is fixed so that one end of the alignment sheet 304 is sandwiched between the attachment member 310 and the upper outer peripheral surface of the connecting portion 306a. The attachment member 310 is a ring-shaped member formed from a metal such as stainless steel or brass. Note that the attachment member 310 may be formed of a resin material such as polyacetal or polybutylene.

  When a magnetic material to be magnetized is attached to the magnetizing device 300, the magnetic material is fitted from the fixed end side, that is, the upper side of the alignment sheet 304. In this case, the magnetic body can be smoothly fitted and the alignment sheet 304 is less likely to be wrinkled.

  When viewed from above (FIG. 3B), the magnetic flux generated when a magnetizing current is passed through the magnetizing coil 302 is substantially four-fold symmetric with respect to the magnetic center O on the symmetry axis S. Become. Here, it can be said that the magnetic center O is a magnetic center in the design of the magnetizing apparatus 300. The four alignment sheets 304 are attached to the magnetizing yoke so as to be substantially symmetric with respect to the magnetic center O when viewed from above. In other words, the four alignment sheets 304 are arranged at equal intervals along the circumferential direction.

  Each magnetized salient pole 306b has an end face 312 that faces the inner circumferential surface 40a of the magnetic material when the magnetic material to be magnetized is attached to the magnetizing device 300. When a magnetizing current flows through the magnetizing coil 302, a magnetic flux is generated from the end surface 312 toward the inner peripheral surface 40a. Each alignment sheet 304 covers at least a part of the end surface 312 of the corresponding magnetized salient pole 306b. In particular, each alignment sheet 304 covers more than half of the end face 312 of the corresponding magnetized salient pole 306b.

  Thereby, when attaching a magnetic body to the magnetizing apparatus 300, even if contact between the end surface 312 of the magnetized salient pole 306b and the inner peripheral surface 40a of the magnetic body is eliminated or contacted, the contact area can be reduced. The surface of the alignment sheet 304 has a dynamic friction coefficient of 0.6 or less, for example, and is slippery. Therefore, the magnetic body can be attached to the magnetizing apparatus 300 more smoothly by reducing or reducing the contact area between the magnetic body made of metal and the magnetized salient pole 306b.

  When the circle in contact with the end face of the magnetized salient pole is large, the curvature of the alignment sheet is small. If this curvature is smaller than the thickness of the alignment sheet, the force that smoothes the gap between the magnetized salient pole and the magnetic material to be magnetized is also reduced, and the effect of suppressing the eccentricity of the drive magnetic pole described later can be reduced. . Correspondingly, in the present embodiment, when the thickness t of the alignment sheet 304 is set in the range of 0.025 (mm) to 0.25 (mm), the eight magnetized salient poles 306b The diameter D0 of the circle in contact with the end surface 312 is set to 30 (mm) or less. As a result, when the magnetic material to be magnetized is attached to the magnetizing device 300, the alignment sheet 304 is sufficiently curved, and the eccentricity of the driving magnetic pole can be suppressed.

を満たすように設定される。これにより、着磁対象の磁性体を着磁装置３００に取り付ける際、調芯シート３０４は十分に湾曲し、駆動用磁極の偏心を抑制できる。 Further, when the diameter D0 is set to a predetermined value, the thickness t (mm) of the alignment sheet 304 is set when the diameter (inner diameter) of the inner peripheral surface 40a of the magnetic material to be magnetized is D1 (mm).

It is set to satisfy. As a result, when the magnetic material to be magnetized is attached to the magnetizing device 300, the alignment sheet 304 is sufficiently curved, and the eccentricity of the driving magnetic pole can be suppressed.

  If the insertion resistance when the magnetic material to be magnetized is fitted to the magnetizing device is large, the work is troublesome and the work efficiency may deteriorate. Furthermore, the alignment sheet wears more frequently, and the frequency of repairs becomes higher, and the work efficiency can deteriorate. Correspondingly, in the magnetizing apparatus 300 according to the embodiment, the thickness t of the alignment sheet 304 is 0.005 (than the assumed interval between the end surface 312 of the magnetized salient pole 306b and the inner peripheral surface 40a. mm). Therefore, the insertion resistance when fitting the magnetic body to the magnetizing device 300 is reduced, and the working efficiency can be improved. Furthermore, wear of the alignment sheet 304 can be reduced.

  If the alignment sheet is too thin, the force for leveling the gap between the magnetized salient pole and the magnetic body can be weakened. Therefore, in the present embodiment, the thickness t of the alignment sheet 304 is set to 0.025 (mm) or more. In this case, it is possible to secure a sufficient force for leveling the gap. On the other hand, if the alignment sheet is too thick, the alignment sheet is not easily bent, and the insertion resistance when the magnetic bodies are fitted together can be increased. Therefore, in the present embodiment, the thickness t of the alignment sheet 304 is set to 0.25 (mm) or less. In this case, the insertion resistance can be suppressed to a level that can withstand practical use.

  The end surface 312 forms part of a cylindrical surface along the symmetry axis S. Each of the magnetized salient poles 306b has a radius of curvature R along the circumferential direction of the end face 312 thereof, that is, a radius of the cylinder, smaller than a radius of a circle in contact with the end faces 312 of the eight magnetized salient poles 306b, ie, D0 / 2. It is formed.

The operation of the magnetizing apparatus 300 configured as described above will be described.
Consider the case of magnetizing a cylindrical magnetic body using the magnetizing device 300.
In the magnetic body attaching step, the cylindrical magnetic body is fitted to the magnetizing device 300 from the fixed end side of the alignment sheet 304. FIG. 4 is a cross-sectional view corresponding to FIG. 3B, showing a state where the magnetic body 400 is attached to the magnetizing device 300. As shown in FIG. 4, the magnetic center O of the magnetizing device 300 and the center U of the magnetic body 400 are in good agreement due to the action of the alignment sheet 304.

  In the magnetization process, a current is passed through the magnetizing coil 302 to magnetize the magnetic body 400. When a current flows through the magnetizing coil 302, a magnetic field is generated around the magnetized salient pole 306b, and the driving magnetic pole is magnetized on the inner peripheral surface 40a of the magnetic body 400. Since the magnetic center O of the magnetizing device 300 and the center U of the magnetic body 400 are in good agreement, the eccentricity of the magnetized driving magnetic pole is substantially small or not.

  According to the magnetizing apparatus 300 according to the present embodiment, the degree of coincidence between the center U of the magnetic body 400 and the magnetic center O of the magnetizing apparatus 300 can be increased by interposing the alignment sheet 304. Therefore, the eccentricity of the magnetized driving magnetic pole can be suppressed. As a result, the vibration derived from the eccentricity of the cylindrical magnet 40 can be reduced in the disk drive device 100 on which the magnetic body magnetized by the magnetizing device 300, that is, the cylindrical magnet 40 is mounted.

  In order to consider the eccentricity suppressing effect of the alignment sheet 304, consider the case where the magnetic body 400 is attached to a magnetizing apparatus from which the alignment sheet 304 has been removed (hereinafter referred to as a magnetizing apparatus according to a comparative example). FIG. 5 is a cross-sectional view corresponding to FIG. 3B, showing a state where the magnetic body 400 is attached to the magnetizing device according to the comparative example.

  In the comparative example, the magnetic body 400 is designed to have a gap between the magnetized salient pole and the magnetic body 400 in a state where the magnetic body 400 is attached to the magnetizing device in order to ensure the ease of mounting and to cope with manufacturing variations. The Here, as shown in FIG. 5, there is a possibility that the magnetic body 400 is fitted in a state where the magnetic body 400 is offset by the gap. In this case, the magnetic center O of the magnetizing device 300 and the center U of the magnetic body 400 are shifted. In this state, when a current is passed through the magnetizing coil 302 and magnetized, the magnetized driving magnetic pole is decentered. When a cylindrical magnet having an eccentric drive magnetic pole is mounted on a disk drive device, for example, a side band component of torque ripple increases and vibration may increase.

  In order to suppress the eccentricity of the driving magnetic pole, a method of increasing the outer peripheral diameter of the magnetized salient pole to reduce the gap is conceivable. However, the fitting is performed when the inner diameter of the magnetic body 400 is the lower limit of the manufacturing variation. May be difficult and may impair workability. Moreover, when fitting the magnetic body 400, the outer periphery of a salient pole may be shaved off by the inner periphery of the magnetic body 400. In this case, as the number of magnetic bodies 400 is magnetized, the outer circumference of the magnetized salient pole gradually wears and becomes smaller, and the roundness of the circle formed by the projecting extreme surface may be impaired. As a result, the eccentricity of the driving magnetic poles of the cylindrical magnet can be further increased, increasing the sideband component of the torque ripple of the disk drive device and possibly inhibiting the capacity increase of the hard disk drive. Therefore, it is difficult to adopt a method in which the outer diameter of the magnetized salient pole is increased to reduce the gap.

Therefore, in the magnetizing apparatus 300 according to the present embodiment, the alignment sheet 304 is interposed between the magnetizing salient pole 306b and the magnetic body 400 to suppress the eccentricity of the driving magnetic pole.
Further, by making one end of the alignment sheet 304 a free end, the alignment sheet 304 bends more freely than when both ends of the alignment sheet 304 are fixed, and the magnetized salient pole 306b and the magnetic material to be magnetized. The deviation of the gap from 400 is further reduced.

If the alignment sheet is formed of a material having a higher hardness than the magnetic material to be magnetized, the inner peripheral surface 40a may be damaged when the magnetic materials are fitted together. If the cylindrical magnet 40 after magnetization is scratched, it may be cracked even by a small impact.
Corresponding to this, in the present embodiment, the alignment sheet 304 is made of a material softer than the magnetic material to be magnetized, thereby making it softer than the magnetic material. In particular, since the magnetic material to be magnetized is formed of a rare earth material such as neodymium, iron, or boron, the alignment sheet 304 includes a polyimide resin or a polyester resin. As a result, the possibility of scratching the magnetized cylindrical magnet 40 can be reduced.

  Further, it can be said that the four alignment sheets 304 are strip-shaped portions divided into four when viewed as a whole. By using the strip shape, the alignment sheet 304 is less likely to be wrinkled by the gap between the end surface 312 of the magnetized salient pole 306b and the inner peripheral surface 40a of the magnetic material to be magnetized. If such wrinkles occur, it becomes difficult to attach the magnetic body to the magnetizing device 300, but such a situation can be avoided.

  When the radius of curvature along the circumferential direction of the end face of each magnetized salient pole is equal to or larger than the radius of a circle in contact with the end faces of the plurality of magnetized salient poles, the insertion resistance when fitting the magnetic material to the magnetizing device is increased. It becomes large and workability may be reduced. Correspondingly, in the present embodiment, each of the magnetized salient poles 306b has a radius of curvature R along the circumferential direction of the end face 312 of the circle that is in contact with the end faces 312 of the eight magnetized salient poles 306b ( D0 / 2) and smaller. Thereby, the contact area of the magnetizing salient pole 306b and the alignment sheet 304 can be reduced, and the insertion resistance can be reduced. As a result, the work becomes easier.

When the magnetization by the magnetizing device 300 is continuously repeated, the temperature of the magnetizing device 300 rises due to the copper loss of the magnetizing coil 302 and the iron loss of the magnetizing salient pole 306b. When the temperature of the magnetizing device 300 rises, the alignment sheet 304 may be softened and the elasticity may be lowered. Further, when the temperature further rises, the alignment sheet 304 may be melted.
Therefore, in the present embodiment, the alignment sheet 304 is formed to have elasticity at a predetermined maximum operating temperature of the magnetizing device 300. For example, when the maximum use temperature of the magnetizing apparatus 300 is set to 80 ° C., the alignment sheet 304 is formed of a material having elasticity even at 80 ° C. For example, a polyimide resin or a polyester resin satisfies this condition. As a result, even if the temperature of the magnetizing device 300 rises, the alignment sheet 304 can maintain necessary elasticity.

  In the magnetizing step, at least one of the time interval between magnetizing and the current at the time of magnetizing may be set so that the temperature of the magnetizing device 300 is equal to or lower than a predetermined maximum operating temperature. . For example, when the maximum operating temperature of the magnetizing apparatus 300 is set to 80 ° C., the time interval between magnetizing may be adjusted so as to be equal to or lower than this temperature. Increasing the time interval between the magnetizations is preferable in that the temperature of the magnetizing apparatus 300 can be kept low, and shortening the time interval between the magnetizations is preferable in terms of increasing work efficiency. Further, it is preferable to reduce the current at the time of magnetization, to keep the temperature of the magnetizing apparatus 300 low, and to increase the current at the time of magnetization to increase the magnetic flux of the driving magnetic pole. The conditions for securing the desired operating temperature of the magnetizing device 300 and the desired magnetic flux of the driving magnetic pole may be obtained by experiments using the time interval between magnetizing and the current during magnetizing as parameters.

  In the magnetizing step, the magnetizing device 300 may be magnetized while being cooled so that the temperature of the magnetizing device 300 is equal to or lower than the maximum operating temperature. For example, you may magnetize, blowing air on the magnetizing apparatus 300 from the air blower which is not shown in figure. In this case, since the temperature rise of the magnetizing apparatus 300 can be suppressed, the work efficiency can be improved by shortening the time interval between the magnetizations. Further, the current at the time of magnetization can be increased to increase the magnetic flux of the driving magnetic pole.

  The configuration and operation of the magnetizing apparatus 300 according to the embodiment have been described above. It is to be understood by those skilled in the art that these embodiments are exemplifications, and that various modifications can be made to combinations of the respective components, and such modifications are within the scope of the present invention.

In the embodiment, the case where the alignment sheet 304 formed in a substantially rectangular sheet shape is used as the alignment member has been described. However, the present invention is not limited to this. For example, instead of the alignment sheet 304, the magnetizing device may include a rod-shaped member having a circular or elliptical cross section formed of the same material as the alignment sheet 304. This rod-shaped member may be disposed between adjacent magnetized salient poles 306b. The rod-like member may be a hollow member. In this case, it becomes easy to adjust to a desired elastic modulus in the thickness direction.
FIG. 6 is a front view showing a magnetizing apparatus 500 according to a modification. 7 is a cross-sectional view taken along the line CC of FIG. The magnetizing device 500 includes a magnetizing coil 302, four rod-shaped members 504, a magnetizing yoke, a magnetizing base 308, and a mounting member 510.

  Each rod-like member 504 is formed such that a cross section (cross section shown in FIG. 7) cut perpendicular to the longitudinal direction has an elliptical shape with a flatness ratio of about 20%. Each bar-like member 504 is provided such that the long axis of the cross section thereof is along the circumferential direction. The attachment member 510 fixes one end of each rod-like member 504 to the upper portion of the connecting portion 306a so that the center line 504a in the short direction of each rod-like member 504 is arranged between the adjacent magnetized salient poles 306b. The other end of each rod-shaped member 504 is a free end.

  The major axis D2 of the cross section of each rod-shaped member 504, that is, the width along the circumferential direction of the rod-shaped member 504 is larger than the interval D3 between adjacent magnetized salient poles 306b. Therefore, when the magnetic body 400 is attached to the magnetizing apparatus 500, the four rod-shaped members 504 are interposed between the eight magnetized salient poles 306b and the inner peripheral surface 40a of the magnetic body 400 to be magnetized. In particular, each bar-like member 504 covers at least a part of the end surface 312 of the corresponding magnetized salient pole 306b.

According to the magnetizing apparatus 500 according to this modification, as in the embodiment, the deviation between the magnetic center O of the magnetizing apparatus 500 and the center U of the magnetic body 400 when the magnetic body 400 is attached to the magnetizing apparatus 500 is reduced. This can reduce the eccentricity of the magnetic pole for driving that is magnetized.
Further, when the magnetic body 400 is fitted, the upper bar-shaped member 504 is less likely to wrinkle than the alignment sheet 304 according to the embodiment. Further, when the maximum radius of curvature of the cross-section of each bar-shaped member 504 is made smaller than the radius (D0 / 2) of the circle in contact with the end faces 312 of the eight magnetized salient poles 306b, the contact between the bar-shaped member 504 and the magnetic body 400 is achieved. This is preferable because the area can be reduced.

In the embodiment, the description has been given of the case where the four alignment sheets 304 are attached to the magnetizing yoke so as to be substantially symmetric with respect to the magnetic center O when viewed from above. I can't. For example, at least one alignment sheet may be provided so as to be symmetric with respect to the magnetic center in the design of the magnetizing device. For example, H (H is an integer of 2 or more) alignment sheets may be provided so as to be H-fold symmetric with respect to the magnetic center. Alternatively, a plurality of alignment sheets may be provided so as to be plane symmetric with respect to a plane including the symmetry axis S. In these cases, the gap between the magnetized salient pole and the magnetic body can be made uniform as in the embodiment, and the eccentricity of the magnetic pole can be reduced.
In the case where three or more alignment sheets are arranged at equal intervals along the circumferential direction, it is preferable in that the deviation of the magnetic material is further reduced as compared with the case where they are attached at unequal intervals.

  As the disk drive device 100 on which the cylindrical magnet 40 generated using the magnetizing device 300 according to the embodiment is mounted, the integrated disk drive device in which the base plate rotatably supports the hub has been described. It is not limited to this. For example, a brushless motor on which a cylindrical magnet generated using the magnetizing apparatus 300 according to the embodiment is mounted may be separately manufactured, and the brushless motor may be attached to the hard disk drive chassis.

  As the disk drive device 100 on which the cylindrical magnet 40 generated using the magnetizing device 300 according to the embodiment is mounted, a so-called outer rotor type disk drive device in which the magnet is located outside the laminated core will be described. However, it is not limited to this. For example, when manufacturing a magnet of a so-called inner rotor type disk drive device in which a magnet is positioned inside a laminated core, the technical idea according to the embodiment may be applied.

  As the disk drive device 100 on which the cylindrical magnet 40 generated using the magnetizing device 300 according to the embodiment is mounted, a disk drive device in which a sleeve is fixed to a base plate and a shaft rotates with respect to the sleeve will be described. However, it is not limited to this. For example, the cylindrical magnet 40 generated by using the magnetizing device 300 according to the embodiment is applied to a shaft-fixed type disk drive device in which the shaft is fixed to the base plate and the sleeve rotates with respect to the shaft together with the hub. May be installed.

  In the embodiment, the case where the magnetizing device 300 is used in the manufacturing process of the cylindrical magnet mainly used in the hard disk drive has been described, but the present invention is not limited to this. For example, a brushless motor having a cylindrical magnet manufactured using the magnetizing device 300 is manufactured, and the brushless motor is applied to an optical disk recording / reproducing device such as a CD (Compact Disc) device or a DVD (Digital Versatile Disc) device. May be installed.

  Although the present invention has been described based on the embodiments, the embodiments merely show the principle and application of the present invention, and the embodiments are defined in the claims. Needless to say, many modifications and arrangements can be made without departing from the spirit of the present invention.

  10 Hub, 20 Shaft, 22 Flange, 40 Cylindrical magnet, 40a Inner peripheral surface, 50 Base plate, 60 Laminated core, 70 Coil, 100 Disk drive device, 200 Magnetic recording disk, 300 Magnetizing device, 302 Magnetized coil, 304 Alignment sheet, 306a connecting portion, 306b magnetized salient pole, 308 magnetized base, 310 attachment member, 400 magnetic body, R motor rotating shaft, O magnetic center.

Claims (10)

A magnetizing device that magnetizes a cylindrical magnetic body,
A plurality of salient poles facing the magnetization target surface of the magnetic body when the magnetic body is attached to the magnetizing device;
A connecting portion for connecting the plurality of salient poles;
An alignment member that includes a portion that is interposed between the plurality of salient poles and the surface to be magnetized and that is bent when the magnetic body is attached ; and an alignment member that adjusts a positional relationship between the plurality of salient poles and the magnetic body; ,
A magnetizing apparatus comprising:   The magnetizing device according to claim 1, wherein the alignment member forms a gap between the bent portion and the plurality of salient poles in a state before the magnetic body is attached. In the state before the magnetic body is attached, the alignment member protrudes to the opposite side to the plurality of salient poles in the radial direction from the cylindrical surface where the bending target surface should be located. The magnetizing apparatus according to claim 1 or 2, characterized in that The alignment member includes a plurality of rectangular portions;
The plurality of rectangular portions are arranged at predetermined intervals along the circumferential direction ,
Magnetization of the plurality of rectangular portions according to any one of claims 1 to 3, characterized that you have a resilience is bent along the magnetization target surface in a state of attaching the magnetic substance apparatus. The alignment member magnetizing apparatus according to any one of claims 1 to 4, characterized in that one end is a free end. The alignment member magnetizing apparatus according to any one of claims 1 to 5, characterized in that it is formed by a softer material than the magnetic body. The alignment member magnetizing apparatus according to any one of claims 1, characterized in that the dynamic friction coefficient is formed containing 0.6 following materials 6. The alignment member includes an alignment sheet formed of an elastic material,
Thickness t of the alignment sheet, where D0 (mm) is the diameter of a circle in contact with the end of the plurality of salient poles facing the magnetization target surface, and D1 (mm) is the diameter of the magnetization target surface. (Mm) is

Magnetizing apparatus according to any one of claim 1, wherein 7 to be set to satisfy. Each protrusion has a radius of curvature along a circumferential direction of an end portion of each salient pole facing the magnetization target surface, which is smaller than a radius of a circle in contact with the end portion of the plurality of salient poles facing the magnetization target surface. magnetizing device according to claim 1, characterized in that the pole is formed 8. Preparing the magnetizing device according to any one of claims 1 to 9 by standing on a magnetizing base having a portion projecting radially outward from an outer diameter of the plurality of salient poles;
The circular cylindrical magnetic body, by fitting the magnetization device from the side opposite to the magnetization base, a step of magnetizing,
Incorporating a magnetized magnetic material as a magnet;
The manufacturing method of the rotary equipment characterized by including.

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