JP4215523B2 - Spindle motor and hard disk drive equipped with the same - Google Patents

Description

[0001]
[Technical field to which the invention belongs]
The present invention relates to a spindle motor that rotationally drives a hard disk and a hard disk drive apparatus including the same.
[0002]
[Prior art]
In general, a spindle motor that rotationally drives a hard disk is configured such that a fixed member rotatably supports a rotor, which is a rotating body, via a bearing means, and a hard disk is disposed on the outer periphery of the rotor. The hard disk drive having the spindle motor is provided with a magnetic head, and the magnetic head has a recording surface of 1 μm or less to the recording surface of the disk in order to read / write information on the disk. There is no gap across the gap.
[0003]
In such a motor, the occurrence of abnormal vibration and noise due to the eccentric gravity center due to processing errors and assembly accuracy of each component such as a rotor and a hard disk may be a problem. Such machining errors and eccentric centroids have been improved by improving the accuracy due to advances in machining technology. However, since certain errors such as tolerances are allowed, the deviation of rotors, hard disks, etc. It is difficult to completely eliminate the development of the mind.
[0004]
In a hard disk drive device in which the rotor rotates at a low speed, the occurrence of the vibration is within an allowable range to such an extent that it does not affect the reading / writing on the disk. In the hard disk drive that rotates at a high speed with the above-mentioned rotational speed, the effect becomes more prominent, and there is a possibility that the magnetic head reads / writes on the hard disk. Therefore, a mechanism for suppressing such influence as much as possible is provided in the motor. There is a need.
[0005]
As a method of correcting the eccentric center of gravity of such a rotor, for example, in a motor in which a shaft fixed to a bracket rotatably supports a rotor via bearing means, the outer periphery of the rotor is disposed above the outer periphery. A peripheral wall portion that hangs down and holds the hard disk in a fixed manner, and a flange portion on which the hard disk is placed are provided below the peripheral wall portion of the rotor. A structure in which an annular holding portion for fixing and holding a balance ring for correcting the heart is formed integrally with a rotor is common (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 eccentric gravity center of the rotor is preferably arranged on the outer peripheral side of the rotor, which can obtain a higher correction effect. This is because the amount of swinging of the rotor increases as the distance from the rotation axis increases.
[0008]
However, in the structure in which the annular holding portion is integrally formed radially outward from the outer peripheral portion of the rotor, the following problems arise.
[0009]
In the case of a hard disk drive for rotating a hard disk, as described above, since there is only a gap of less than 1 μm between the recording surface of the disk and the magnetic head, the generation of fine dust is also caused by the disk or head. Depending on the material of the magnetic material, oil smoke and chemical substances may cause the performance of the hard disk and magnetic head to deteriorate. High cleanliness is required.
[0010]
For this reason, it is not possible to form a member that constitutes a motor or the like by a processing means such as casting, in which fine holes are exposed on the surface and it is difficult to remove processing powder, processing oil, etc. by washing, and metal bars Generally, a method of forming by cutting is employed. In addition, since the number of hard disks based on glass is increasing, the rotor material is made of stainless steel rather than aluminum and aluminum alloys, which have been widely used in the past, taking into account the characteristics such as the coefficient of thermal expansion. Many have come to be used.
[0011]
However, such stainless steel rods have only an outer diameter of 35 mm or less, but in a motor that drives 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 cleanliness required in the hard disk drive, it is necessary to make a special order for the rod material used as the rotor material. To that end, a large capital investment is required, such as newly preparing production equipment. It is difficult to realize in terms of member costs. Furthermore, since only the annular holding part for holding the balance ring is left, the number of cutting parts increases, which is inefficient from the viewpoint of processing cost.
[0013]
The present invention has been made in view of the above problems, and its object is to avoid an increase in member costs and processing costs when forming an annular holding portion on the outer peripheral portion of the rotor, and 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 problems, in the spindle motor according to claim 1 of the present invention, a fixed member and a rotor that is formed into a substantially cup shape by cutting stainless steel and is rotatably supported by the fixed member. And a circumferential wall portion that hangs down from the outer peripheral portion of the rotor, the recording disk is disposed, a flange portion that is positioned below the peripheral wall portion, and on which the recording disk is placed, and an outer peripheral portion of the rotor, In a spindle motor provided with a mechanism for correcting the bias, the mechanism for correcting the bias in the center of gravity position of the rotor is a substantially ring-shaped member for correcting the bias in the center of gravity position of the rotor, and the substantially ring-shaped member is fixed. And an annular member mounted on the outer periphery 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 fitted with a substantially ring-shaped member to the outer periphery of the rotor. In other words, since the rotor and the mechanism for correcting the deviation of the center of gravity of the rotor are formed by separate members, the rotor and the mechanism for correcting the deviation of the center of gravity of the rotor are integrated, compared to the one in which the rotor and the mechanism for correcting the deviation of the center of gravity of the rotor are integrated. The diameter can be reduced.
[0016]
Therefore, since the member which forms a rotor can use the bar material of 35 mm or less of stainless steel, the increase in the member cost accompanying the enlargement of a rotor diameter can be suppressed. 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, it is possible to reduce the machining time and machining man-hours by cutting compared to the one that is formed integrally. Thus, it is possible to provide a spindle motor with improved production efficiency and excellent mass productivity.
[0017]
Further, the annular member is characterized by being fixed radially outward of the flange portion of the rotor.
[0018]
By doing so, in addition to being able to reduce the diameter of the rotor, it is possible to more effectively correct the contact around the rotor due to the deviation of the center of gravity of the rotor.
[0019]
In the hard disk drive device according to claim 3, the spindle motor according to claim 1, which is fixed to the housing and the top surface side and the bottom surface side of the housing, respectively, and the rotor outer periphery of the spindle motor, A fixed recording disk capable of reading and writing information and an information access means for writing or reading information at a required position of the recording disk are provided.
[0020]
By using such a spindle motor, the occurrence of vibration and noise as a hard disk drive device can be reduced and the cost can be reduced. For this reason, it can be suitably used for devices such as hard disk video recorders that require quietness.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a spindle motor and a hard disk drive including the spindle motor according to an embodiment of the present invention 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 the sake of convenience, but the direction in the actual attachment state is not limited.
[0022]
As shown in FIG. 1, the spindle motor according to this embodiment basically includes a base plate 2, a shaft 6 that is erected and fixed to the base plate 2, and a rotor 8 that is rotatably supported by the shaft 6. It is configured.
[0023]
An annular boss 2a is provided around the center hole in which one end of the shaft 6 is fitted and fixed at the center of the base plate 2 constituting the stationary member, 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 adhesion. The shaft 6 is a hollow cylinder in which a through-hole penetrating in the axial direction is formed, and is formed of a relatively rigid member such as iron or stainless steel.
[0024]
The rotor 8 that is a rotating member includes a hollow cylindrical sleeve 10 in which a central hole through which the shaft 6 is inserted is formed, and a substantially cup-shaped rotor hub 11 in which the sleeve 10 is fitted and 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 thermal expansion coefficient. .
[0025]
An annular flange 11b on which the hard disk 30 is placed 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 and the outer peripheral surface of the shaft 6 are opposed to each other in a radial direction through a minute gap in which lubricating oil is held, and a pair of radial dynamic pressure bearings separated in the axial direction are provided in the minute gap. 13 and 14 are formed.
[0027]
The radial dynamic pressure bearings 13 and 14 have shafts on the inner peripheral surface of the sleeve 10 so as to induce a moving pressure axially outward (toward the upper and lower ends of the sleeve 10) with respect to the lubricating oil when the rotor 8 rotates. A herringbone groove having an unbalanced shape in the direction is formed.
[0028]
Disc-shaped thrust plates 15 and 16 projecting radially outward are fixed to the upper and lower portions of the shaft 6, respectively, and the thrust plates 15 and 16 are provided to the upper and lower portions of the sleeve 10. A stepped portion for storage is formed. The lower end surfaces of the thrust plates 15 and 16 and the end surfaces of the sleeves 10 facing the thrust plates 15 and 16 in the axial direction are opposed to each other in the axial direction through a minute gap in which lubricating oil is held, and are spaced apart in the axial direction. A pair of thrust dynamic pressure bearings 18 and 19 are formed.
[0029]
The thrust hydrodynamic bearings 18 and 19 are provided on the flat surface of the step portion of the sleeve 10 that is axially opposed to the thrust plates 15 and 16 and radially inward with respect to the lubricating oil when the rotor 8 rotates (the outer circumferential direction of the shaft 6). The spiral groove is formed so as to induce the movement pressure in
[0030]
Next, the configuration and principle of the present invention will be described with reference to FIG. 2 is a partially enlarged cross-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 at the lower portion of 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 placed on the upper surface of the flange portion 11b, and is sandwiched between the upper surface of the flange portion 11b and the clamp member 34 from the axial direction, and is fixedly held.
[0032]
The balance holder 20 is fitted and fixed to the outer peripheral side of the flange portion 11b by means such as press fitting and adhesion. The balance holder 20 is an annular member, and has a through hole in the central portion, and the central portion is fitted and fixed to the outer peripheral portion of the flange portion 11 b of the rotor hub 11.
[0033]
Inside the balance holder 20, a recess is provided in an annular shape, and a pair of annular grooves 20a into which the balance ring 22 is fitted and fixed are provided on the inner peripheral surface of the recess so as to be 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 in which a part thereof is 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 disposed at a portion where the center of gravity is biased due to a processing error or assembly error of the rotor 8 measured when the motor rotates. Fixed.
[0036]
By doing so, the center of gravity of the balance ring 22 is arranged at a position that is 180 degrees opposite to the eccentric part of the rotor 8, so that the contact around the eccentricity of the rotor 8 can be corrected well, It is possible to suppress the vibration of the rotor 8 and the generation of noise due to this.
[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 a thermal expansion coefficient comparable to that of the rotor hub 11 is suitable so as not to cause a fitting omission from the balance holder 20. For example, a stainless steel magnetic material is preferable.
[0038]
One or a plurality of balance rings 22 can be provided in the annular groove 20a of the recess of the balance holder 20, and can be appropriately selected so as to suppress vibration caused by the eccentric gravity center of the rotor 8.
[0039]
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 thereto, and the balance rings are provided to be separated from each other in the radial direction. It is also possible to arrange them.
[0040]
As described above, the diameter of the rotor 8 can be reduced by fixing the balance holder 20 to the outer side in the radial direction of the flange portion 11 b of the rotor hub 11. That is, since the rotor 8 and the mechanism for correcting the deviation of the center of gravity of the rotor 8 are formed by different members, the rotor 8 and the mechanism for correcting the deviation of the center of gravity of the rotor 8 are integrated. In comparison, the diameter of the rotor 8 can be reduced.
[0041]
Therefore, a stainless steel bar of 35 mm or less can be used as a member forming the rotor 8, so that an increase in member cost accompanying an increase in the diameter of the rotor 8 can be suppressed. Also in the manufacturing process, the rotor 8 and the mechanism for correcting the deviation of the center of gravity of the rotor 8 are formed by separate members, so that the machining time and machining man-hours for cutting are reduced as compared with those formed integrally. Production efficiency. In addition, by fixing the balance holder 20 to the outer side in the radial direction of the flange portion 11b of the rotor hub 11, it is possible to more effectively correct the contact around the rotor hub 11 due to the eccentric center of gravity.
[0042]
Next, the internal configuration of a general hard disk drive 40 will be described with reference to FIG.
[0043]
The hard disk drive device 40 is composed of a rectangular housing 42, and the inside of the housing 42 forms a clean space with extremely little dust, dust, etc., and a disk-like shape for recording information in the interior. A spindle motor 44 on which the disc 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 the head 52. The supporting arm 50, the head 52, and the arm 50 are configured by an actuator unit 48 that moves the arm 50 to a required position on the disk plate 46.
[0045]
Although the embodiments according to the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications and corrections can be made without departing from the scope of the present invention.
[0046]
For example, in this embodiment, a hydrodynamic bearing is used as the bearing structure, but the same operation and effect as in the present invention can be obtained even if a ball bearing motor using a ball bearing is used.
[0047]
In this embodiment, the lubricating oil is used as the fluid of the dynamic pressure bearing. However, even if a motor using a so-called air dynamic pressure bearing using air as a fluid is used, the same operation and effect as the present invention can be obtained. It is done.
[0048]
In addition, in the present embodiment, the shaft-fixed motor is used. However, the present invention is not limited to this, and the same operation and effect as in the present invention can be obtained even when a shaft-rotating motor whose shaft rotates integrally with the rotor is used. .
[0049]
【The invention's effect】
In the spindle motor according to claim 1, a mechanism for correcting the deviation of the center of gravity of the rotor is provided on the outer peripheral portion of the rotor. Therefore, the rotor is compared with the one that integrally forms the rotor and the mechanism. The diameter can be reduced.
[0050]
Further, 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 contact around the rotor due to the deviation of the center of gravity of the rotor is further effective. Can be corrected.
[0051]
In the hard disk drive device according to claim 3, by using the spindle motor according to claim 1 and claim 2, the generation of vibration and noise as the hard disk drive device can be reduced and the cost can be reduced. It becomes possible.
[0052]
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an embodiment of the present invention.
FIG. 2 is an enlarged cross-sectional view of a main part according to an embodiment of the present invention.
FIG. 3 is a view showing a balance ring according to an embodiment of the present invention.
FIG. 4 is a cross-sectional view showing a hard disk drive device.
[Explanation of symbols]
2 Base plate 4 Stator 6 Shaft 8 Rotor 10 Sleeve 11 Rotor hub 11a Peripheral wall portion 11b Gutter portion 20 Balance holder 20a Annular groove 22 Balance ring 22a Opening portion 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 fixing member;
A peripheral wall portion hanging from the outer peripheral portion of the rotor and on which a recording disk is disposed;
Located on the lower side of the peripheral wall portion, formed to project radially outward from the peripheral wall portion, and a flange portion on which the recording disk is placed;
A spindle motor that is located on the outer periphery of the rotor and has a mechanism that corrects the deviation of the center of gravity of the rotor,
The mechanism for correcting the deviation of the center of gravity of the rotor is:
A substantially ring-shaped member that corrects the deviation of the center of gravity of the rotor;
The substantially ring-shaped member is fixedly held, and is composed of an annular member attached to the outer periphery of the rotor ,
The substantially ring-shaped member and the annular member are formed by a member different from the rotor,
The spindle motor according to claim 1, wherein the annular member is fixed to an outer peripheral portion of a flange portion of the rotor. 2. The spindle motor according to claim 1, wherein a concave portion is provided in an annular shape inside the annular member, and one or more annular grooves are provided on an inner peripheral surface of the concave portion. . A housing;
The spindle motor according to any one of claims 1 and 2, which is fixed to a top surface side and a bottom surface side of the housing, respectively.
A recording disk fixed to the outer periphery of the spindle motor and capable of reading and writing information;
A hard disk drive device comprising information access means for writing or reading information at a required position on the recording disk.

Images