JP2004229333A - Spindle motor, hard disk drive equipped therewith - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a spindle motor which can suppress the member cost and the processing cost and is excellent in mass productivity by forming a mechanism for modifying wobble caused by mass eccentricity of a rotor at the periphery of the rotor, and a hard disc drive which is equipped with it. <P>SOLUTION: The spindle motor is equipped with a shaft 6, a rotor 8 supported rotatably by the rotor 6, a peripheral wall 11a hanging down the periphery of the rotor 8 and having a hard disc 30 arranged around, and a flange 11b positioned under the peripheral wall 11a and having the hard disc 30 placed thereon. Further in the motor, a balance holder 20 which fixedly holds a balance ring 22 for modifying the wobble caused by mass eccentricity of the rotor 8 is mounted outside in the diametrical direction of the flange 11b of the rotor 8. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a spindle motor for rotating a hard disk and a hard disk drive provided with the same.
[0002]
[Prior art]
In general, a spindle motor that rotationally drives a hard disk has a configuration in which a fixed member rotatably supports a rotor, which is a rotating body, via bearing means, and a hard disk is arranged on an outer peripheral portion of the rotor. A magnetic head is arranged in the hard disk drive provided with the spindle motor. The magnetic head fills the recording surface of the disk with a recording surface of 1 μm in order to read / write information from / to the disk. Facing each other with no gap.
[0003]
In such a motor, there may be a problem in that abnormal vibrations and noises are generated due to eccentricity due to processing errors and assembly accuracy of components such as a rotor and a hard disk. Such processing errors and eccentricity have been improved by improving the accuracy with the progress of processing technology.However, since certain errors such as tolerances are allowed, the eccentricity of the rotor, hard disk, etc. It is difficult to completely eliminate the occurrence of the mind.
[0004]
In a hard disk drive in which the rotor rotates at a low speed, the occurrence of the above-mentioned vibration is within an allowable range as long as it does not affect the reading / writing to the disk. However, the rotation of the rotor is 7200 rpm / min, 10000 rpm / min. In a hard disk drive that rotates at a high speed at the above rotation speed, the effect is more remarkable, and a problem may occur in reading / writing data from / to the hard disk by a magnetic head. Therefore, a mechanism for minimizing such an effect is provided in the motor. There is a need.
[0005]
As a method of correcting such an eccentricity of the rotor, for example, in a motor in which a shaft fixed to a bracket rotatably supports a rotor via bearing means, an upper part of the outer periphery of the rotor is provided from the outer periphery. A peripheral wall portion that hangs down and fixedly holds the hard disk, and a flange portion on which the hard disk is placed are provided below the peripheral wall portion of the rotor. Generally, a structure in which an annular holding portion for fixing and holding a balance ring for correcting a center is formed integrally with a rotor (see Patent Document 1).
[0006]
[Patent Document 1]
US Patent Application Publication No. 2002/0089252 (FIG. 1)
[0007]
[Problems to be solved by the invention]
Such a mechanism for correcting the eccentricity of the rotor is preferably arranged on the outer peripheral side of the rotor where a higher correction effect can be obtained. This is because the whirling amount of the rotor increases as the distance from the rotation axis increases.
[0008]
However, such a structure in which the annular holding portion is integrally formed radially outward from the outer peripheral portion of the rotor has the following problems.
[0009]
In the case of a hard disk drive that rotationally drives a hard disk, as described above, only a gap of less than 1 μm is provided between the recording surface of the disk and the magnetic head. It may lead to damage to the motor and head actuators, etc., since oil fumes and chemical substances can also degrade the performance of hard disks and magnetic heads, depending on the magnetic material. High cleanliness is required.
[0010]
For this reason, fine holes are exposed on the surface, and it is not possible to form a member constituting a motor or the like by processing means such as casting in which it is difficult to remove processing powder, processing oil, and the like by washing. Is generally adopted by cutting the material. In addition, as hard disks using glass as a base material are increasing, stainless steel is used as the material of the rotor in consideration of characteristics such as the coefficient of thermal expansion of aluminum and aluminum alloys, which have been widely used in the past. It is increasingly used.
[0011]
However, there is only a bar material such as stainless steel having an outer diameter of 35 mm or less, but in a motor for driving a 3.5-inch hard disk, a balance ring for correcting the center of gravity is held on the outer periphery of the rotor. When the annular holding portion is integrally formed, the outer diameter of the rotor may exceed 35 mm.
[0012]
Therefore, in order to maintain the required cleanliness of the hard disk drive, it is necessary to specially order the rod material for the rotor, but for that purpose, a large capital investment is required, such as setting up new manufacturing facilities. However, it is difficult to realize this in terms of member costs. Further, since only the annular holding portion for holding the balance ring is left, the number of cutting portions increases, which is inefficient in terms of processing cost.
[0013]
The present invention has been made in view of the above problems, and an object of the present invention is to avoid an increase in member cost and processing cost when forming an annular holding portion on an outer peripheral portion of a rotor, to achieve a spindle motor excellent in mass productivity, and An object of the present invention is to provide a hard disk drive provided with this.
[Means for Solving the Problems]
In order to solve the above-mentioned problem, in the spindle motor according to claim 1 of the present invention, a fixed member and a rotor formed into a substantially cup shape by cutting stainless steel and rotatably supported by the fixed member. And a peripheral wall portion hanging down from the outer peripheral portion of the rotor, on which the recording disk is disposed, a flange portion located below the peripheral wall portion, on which the recording disk is mounted, and an outer peripheral portion of the rotor having a center of gravity position of the rotor. And a mechanism for correcting the deviation of the center of gravity of the rotor, wherein the mechanism for correcting the deviation of the center of gravity of the rotor includes a substantially ring-shaped member for correcting the deviation of the center of gravity of the rotor, and a fixed ring-shaped member. , And an annular member mounted on the outer peripheral portion of the rotor.
[0014]
Here, the outer peripheral portion of the rotor refers to the inner peripheral portion and the outer peripheral portion of the peripheral wall portion of the rotor, and the inner peripheral portion, the outer peripheral portion, and the lower end portion of the flange portion of the rotor.
[0015]
The diameter of the rotor can be reduced by fixing an annular member having a substantially ring-shaped member attached to the outer peripheral portion of the rotor. That is, since the rotor and the mechanism for correcting the bias of the center of gravity of the rotor are formed by separate members, the rotor and the mechanism for correcting the bias of the center of gravity of the rotor are integrated with each other. The diameter can be reduced.
[0016]
Therefore, since a member forming the rotor can be a stainless steel bar having a diameter of 35 mm or less, it is possible to suppress an increase in member costs due to an increase in the diameter of the rotor. Also, in the manufacturing process, since the rotor and the mechanism for correcting the deviation of the center of gravity of the rotor are formed by separate members, the processing time and the number of processing steps by cutting can be reduced as compared with those formed integrally. Thus, it is possible to provide a spindle motor with improved production efficiency and excellent mass productivity.
[0017]
In the spindle motor according to the second aspect, the annular member is fixed radially outward of the flange of the rotor.
[0018]
By doing so, the diameter of the rotor can be reduced, and the rotation of the rotor due to the bias of the center of gravity of the rotor can be more effectively corrected.
[0019]
In the hard disk drive according to the third aspect, the housing, the spindle motor according to any one of the first and second aspects, which are fixed to the top surface and the bottom surface of the housing, respectively, and the outer peripheral portion of the rotor of the spindle motor. It is characterized by comprising a fixed recording disk capable of reading and writing information and information access means for writing or reading information at a required position on the recording disk.
[0020]
By using such a spindle motor, the generation of vibration and noise as a hard disk drive is reduced, and the cost can be reduced. Therefore, the present invention can be suitably used for a device requiring quietness, such as a hard disk / video recorder.
[0021]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a spindle motor according to an embodiment of the present invention and a hard disk drive including the same will be described with reference to FIGS. In the description of the present embodiment, the vertical direction of each drawing is referred to as “vertical direction” for convenience, but the direction in the actual mounting state is not limited.
[0022]
As shown in FIG. 1, the spindle motor according to the present embodiment basically includes a base plate 2, a shaft 6 erected and fixed to the base plate 2, and a rotor 8 rotatably supported by the shaft 6. It is configured.
[0023]
An annular boss 2a is provided at the center of the base plate 2 constituting the stationary member, around a center hole into which one end of the shaft 6 is fitted and fixed, and on the outer peripheral side of the boss 2a. Is formed with a cylindrical portion 2b to which the stator 4 is fixed by means such as press fitting or bonding. The shaft 6 is a hollow cylinder having a through-hole penetrating the shaft 6 in the axial direction, and is formed of a relatively rigid member such as iron or stainless steel.
[0024]
The rotor 8, which is a rotating member, includes a hollow cylindrical sleeve 10 having a central hole through which the shaft 6 is inserted, and a substantially cup-shaped rotor hub 11 into which the sleeve 10 is fixed. In this case, the sleeve 10 is formed from a relatively soft metal such as a copper alloy in consideration of workability, and the rotor hub 11 is formed from a stainless steel such as DHS (registered trademark) -1 having a small coefficient of thermal expansion. .
[0025]
An annular flange portion 11b on which the hard disk 30 is mounted is provided on the outer peripheral surface of the peripheral wall portion 11a constituting the outer wall of the rotor hub 11, and the rotor magnet 12 is bonded to the inner peripheral surface of the peripheral wall portion 11b. It is fixed by means of.
[0026]
Next, the bearing structure will be described. The inner peripheral surface of the sleeve 10 radially opposes the outer peripheral surface of the shaft 6 via a minute gap in which lubricating oil is held, and a pair of radial dynamic pressure bearings axially separated from each other in the minute gap. 13 and 14 are formed.
[0027]
The radial dynamic pressure bearings 13 and 14 are provided with shafts on the inner peripheral surface of the sleeve 10 so as to induce a moving pressure with respect to the lubricating oil outwardly (in the direction of the upper and lower ends of the sleeve 10) when the rotor 8 rotates. A herringbone groove having an unbalanced shape in the direction is formed.
[0028]
Disk-shaped thrust plates 15 and 16 projecting outward in the radial direction are fixed to the upper and lower portions of the shaft 6, respectively, and these thrust plates 15 and 16 are fixed to the upper and lower portions of the sleeve 10, respectively. A step portion for storing is formed. The lower end surfaces of the thrust plates 15 and 16 and the end surface of the sleeve 10 axially facing the thrust plates 15 and 16 are axially opposed via a minute gap in which lubricating oil is held, and are separated in the axial direction. A pair of thrust dynamic pressure bearings 18 and 19 are formed.
[0029]
The thrust dynamic pressure bearings 18 and 19 are provided with a stepped flat surface of the sleeve 10 which faces the thrust plates 15 and 16 in the axial direction. A spiral groove is formed so as to induce a moving pressure in (1).
[0030]
Next, the configuration and principle of the present invention will be described with reference to FIG. FIG. 2 is a partially enlarged sectional view showing the vicinity of the lower portion of the peripheral wall portion 11a of the rotor hub 11 in FIG.
[0031]
An annular flange portion 11b is provided below the outer peripheral surface of the peripheral wall portion 11a so as to project radially outward from the outer peripheral portion of the peripheral wall portion 11a. The hard disk 30 is mounted on the upper surface of the flange 11b, and is fixedly held between the upper surface of the flange 11b and the clamp member 34 in the axial direction.
[0032]
A balance holder 20 is fitted and fixed to the outer peripheral side of the flange portion 11b by means such as press-fitting and bonding. The balance holder 20 is an annular member and has a through-hole at the center, and the center is fitted and fixed to the outer periphery of the flange 11 b of the rotor hub 11.
[0033]
A concave portion is provided in the inside of the balance holder 20 in a ring shape, and a pair of annular grooves 20 a in which the balance ring 22 is fitted and fixed are provided on the inner peripheral surface of the concave portion, which are spaced apart in the axial direction.
[0034]
As shown in FIG. 3, the balance ring 22 is a substantially C-shaped member in plan view, and has an opening 22a with a part cut out.
[0035]
The balance ring 22 is fitted to the balance holder 20 so that the opening 22a of the balance ring 22 is arranged at a position where the center of gravity is deviated due to a processing error or an assembly error of the rotor 8 measured during rotation of the motor. Fixed.
[0036]
By doing so, the center of gravity of the balance ring 22 is arranged at a position 180 degrees opposite to the eccentric portion of the rotor 8, so that it is possible to satisfactorily correct the touch around due to the eccentricity of the rotor 8, Vibration of the rotor 8 and generation of noise due to the vibration can be suppressed.
[0037]
The balance holder 20 and the balance ring 22 are formed of iron, stainless steel, aluminum, or the like. Among them, the balance holder 20 and the balance ring 22 are formed by the thermal expansion of the rotor hub 11 during high-speed rotation. A member having the same thermal expansion coefficient as that of the rotor hub 11 is suitable so that the fitting is not disengaged from the balance holder 20, and for example, stainless steel as a magnetic material is preferable.
[0038]
One or more balance rings 22 can be provided in the annular groove 20 a in the concave portion of the balance holder 20, and can be appropriately selected so as to suppress vibration caused by the eccentricity of the rotor 8.
[0039]
Further, in the embodiment of the present invention, the annular grooves 20a of the balance holder 20 are provided apart from each other in the axial direction. However, the present invention is not limited to this. It is also possible to arrange in.
[0040]
As described above, by fixing the balance holder 20 radially outward of the flange 11b of the rotor hub 11, the diameter of the rotor 8 can be reduced. That is, since the rotor 8 and the mechanism for correcting the bias of the center of gravity of the rotor 8 are formed by separate members, the rotor 8 and the mechanism for correcting the bias of the center of gravity of the rotor 8 are integrated. In comparison, the diameter of the rotor 8 can be reduced.
[0041]
Accordingly, since a bar member of stainless steel having a diameter of 35 mm or less can be used as a member forming the rotor 8, an increase in member cost due to an increase in the diameter of the rotor 8 can be suppressed. Also in the manufacturing process, since the rotor 8 and the mechanism for correcting the deviation of the center of gravity of the rotor 8 are formed by separate members, the processing time and the number of processing steps by cutting are reduced as compared with those integrally formed. Can increase production efficiency. In addition, by fixing the balance holder 20 radially outward of the flange portion 11b of the rotor hub 11, it is possible to more effectively correct the rotation around the rotor hub 11 due to the eccentricity.
[0042]
Next, the internal configuration of a general hard disk drive 40 will be described with reference to FIG.
[0043]
The hard disk drive 40 comprises a housing 42 having a rectangular shape. The interior of the housing 42 forms a clean space with extremely little dust and dirt, and has a disk-shaped space for recording information. The spindle motor 44 on which the disk plate 46 is mounted is disposed.
[0044]
A head moving mechanism 54 for reading / writing information from / to the disk plate 46 is disposed inside the housing 42. The head moving mechanism 54 includes a head 52 for reading / writing information on the disk plate 46, and a head 52 for reading / writing information from / to the disk plate 46. It is composed of a supporting arm 50, a head 52, and an actuator section 48 for moving the arm 50 to a required position on the disk plate 46.
[0045]
As described above, the embodiments according to the present invention have been described. However, the present invention is not limited to the above-described embodiments, and various changes and modifications can be made without departing from the scope of the present invention.
[0046]
For example, in the present embodiment, the dynamic pressure bearing is used as the bearing structure. However, the same operation and effect as the present invention can be obtained by using a ball bearing motor using a ball bearing.
[0047]
Further, in the present embodiment, the lubricating oil is used as the fluid of the dynamic pressure bearing. However, the same operation and effect as those of the present invention can be obtained by using a motor using air, that is, a so-called air dynamic pressure bearing. Can be
[0048]
In addition, in the present embodiment, the motor is a shaft-fixed motor. .
[0049]
【The invention's effect】
In the spindle motor according to the first aspect, since a mechanism for correcting the deviation of the position of the center of gravity of the rotor is provided on the outer peripheral portion of the rotor, the rotor is compared with one in which the rotor and the mechanism are integrally formed. The diameter can be reduced.
[0050]
In the spindle motor according to the second aspect, since the annular member is fixed radially outward of the flange portion of the rotor, the diameter of the rotor can be reduced, and the center of gravity of the rotor is biased. The rotation around the rotor can be corrected more effectively.
[0051]
In the hard disk drive according to the third aspect, by using the spindle motor according to the first and second aspects, the generation of vibration and noise as the hard disk drive can be reduced, and the cost can be reduced. Will be possible.
[0052]
[Brief description of the drawings]
FIG. 1 is a sectional view showing an embodiment of the present invention.
FIG. 2 is an enlarged sectional view of a main part according to the embodiment of the present invention.
FIG. 3 is a diagram showing a balance ring according to the embodiment of the present invention.
FIG. 4 is a sectional view showing a hard disk drive.
[Explanation of symbols]
2 Base plate 4 Stator 6 Shaft 8 Rotor 10 Sleeve 11 Rotor hub 11a Peripheral wall 11b Flange 20 Balance holder 20a Annular groove 22 Balance ring 22a Opening 30 Hard disk

Claims (3)

A fixing member,
A rotor that is formed into a substantially cup shape by cutting stainless steel, and is rotatably supported by the fixed member;
A peripheral wall portion hanging down from an outer peripheral portion of the rotor and on which a recording disk is disposed;
A flange portion located below the peripheral wall portion, on which the recording disk is mounted,
A mechanism for correcting the deviation of the center of gravity of the rotor on the outer periphery of the rotor;
A mechanism for correcting the deviation of the center of gravity position of the rotor,
A substantially ring-shaped member for correcting the deviation of the position of the center of gravity of the rotor,
A spindle member fixedly holding the substantially ring-shaped member and an annular member mounted on an outer peripheral portion of the rotor. The spindle motor according to claim 1, wherein the annular member is fixed radially outward of a flange of the rotor. A housing,
The spindle motor according to claim 1, wherein the spindle motor is fixed to a top surface side and a bottom surface side of the housing, respectively.
A recording disk fixed to the outer peripheral portion of the rotor of the spindle motor and capable of reading and writing information,
A hard disk drive comprising: an information access unit for writing or reading information at a required position on the recording disk.

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