WO2011099370A1

WO2011099370A1 - Subassembly of disk drive device

Info

Publication number: WO2011099370A1
Application number: PCT/JP2011/051545
Authority: WO
Inventors: 寛齋藤
Original assignee: アルファナテクノロジー株式会社
Priority date: 2010-02-15
Filing date: 2011-01-27
Publication date: 2011-08-18
Also published as: JP4860014B2; JPWO2011099370A1

Abstract

Disclosed is a subassembly of a disk drive device for reducing the slope of a surface on which a recording disk is placed. The subassembly (100) is provided with a base plate (10), a hub (12) upon which a recording disk (200) is to be placed, a shaft (16) coupled to an aperture portion (12d) of the center of the hub (12), and a bearing unit for supporting the shaft (16) so as to be rotatable relative to the base plate (10). The hub (12) comprises a barrel for holding the recording disk (200) and an outer extending portion (46) arranged consecutively thereto, and a seating surface (12b) formed upon the outer extending portion (46). In addition, the aperture portion (12d) has been configured to maintain a pressure-contact state with the shaft (16) at the temperature of processing when applying aging processing to at least the coupled portions of the hub (12) and the shaft (16) so that the slope value of the disk seating surface defined in a coupled state of the aperture portion (12d) with the shaft (16) falls to or below a pre-defined maximum tolerance with respect to a surface perpendicular to the axial direction.

Description

Disk drive subassembly

The present invention relates to a sub-assembly of a disk drive device, particularly to a technique for reducing the inclination of a surface on which a recording disk is placed.

A hard disk drive (HDD) is known as a medium used for a storage device of a computer. In an HDD, a recording disk on which recording tracks are formed is rotated at a high speed by a brushless motor. In order to read / write the magnetic data contained in the recording track during this high-speed rotation, a recording / reproducing head is arranged so as to maintain a slight gap with respect to the surface of the recording disk (see, for example, Patent Document 1). ).

JP 2005-127405 A

By the way, as one method for increasing the capacity of the HDD, it is conceivable to reduce the width of the recording track and bring the recording / reproducing head closer to the surface of the recording disk. However, the recording disk may be supported by a hub that is a rotating part of the brushless motor with the recording disk tilted. The recording disk is supported by an extension part formed on the hub of the brushless motor. For example, the axial height of the disk seating surface of the extension part may vary in the circumferential direction. In other words, since the seating surface is inclined with respect to the rotation axis, there is a maximum value and a minimum value for the height in the axial direction, and the difference in height (hereinafter referred to as the seating surface tilt, which is referred to as a seating surface tilt value). ) May occur. When the seating surface is inclined, the recording disk is attached with an inclination. When the recording disk is tilted, the recording / reproducing head tilts and traces, and so-called head touch characteristics deteriorate. If the head touch characteristics are deteriorated, the HDD data read / write error rate may be deteriorated, which may cause an increase in capacity. In particular, a so-called 3.5-inch HDD has a recording disk with a large diameter of about 95 mm, and the influence of the inclination of the recording disk appears remarkably when the recording / reproducing head traces the vicinity of its outer periphery.

In the initial stage of assembly, even if the brushless motor has a small seating surface tilt value, the residual stress at the joint between the shaft and hub is released due to changes over time. The value may increase. As a result, the inclination of the recording disk placed thereon also increases, which may cause the above-described problem.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a sub-assembly of a disk drive device in which the inclination of a surface on which a recording disk is placed is reduced including a change with time.

In order to solve the above problems, a sub-assembly of a disk drive device according to an aspect of the present invention includes a base member, a hub on which a recording disk is to be placed, a shaft coupled to an opening hole in the center of the hub, A bearing unit that supports the shaft so as to be rotatable relative to the base member. The hub includes an outer cylinder portion that extends in the axial direction of the bearing unit to hold the recording disk, an outer extension portion that is connected to the outer cylinder portion and extends radially outward of the recording disk, and an outer extension portion. A disk seating surface formed. With respect to the surface orthogonal to the axial direction, the opening hole portion is connected to the hub so that the inclination value of the disc seating surface determined by the coupling state of the opening hole portion of the hub and the shaft is not more than a predetermined maximum allowable value. The pressure contact state with the shaft is maintained at the treatment temperature when the aging treatment is performed on at least the coupling portion of the shaft.

According to this aspect, the pressure contact state between the shaft and the opening hole is maintained at the processing temperature when the aging treatment is performed on at least the coupling portion of the hub and the shaft. In other words, even if thermal expansion occurs at the joint during the aging treatment performed to remove the residual stress at the hub-shaft joint, the hub and shaft are in pressure contact, so the posture of both is the same as before and after the aging treatment. It is hard to change. In other words, if the pressure contact state of the hub and the shaft is determined so that the inclination value of the disc seating surface determined by the coupling state of the opening hole portion of the hub and the shaft is not more than a predetermined maximum allowable value, the aging treatment is performed. Even if applied, it is possible to suppress the inclination value of the disc seating surface from changing greatly. In addition, since a part of the residual stress can be released by the aging treatment, the occurrence of the seating surface inclination due to the release of the residual stress can be suppressed in the change with time after assembly. The “disc drive device sub-assembly” may be a device for driving a recording disk, for example, a brushless motor.

It should be noted that any combination of the above-described constituent elements and those obtained by mutually replacing constituent elements and expressions of the present invention among methods, apparatuses, systems, etc. are also effective as an aspect of the present invention.

According to the present invention, it is possible to provide a sub-assembly of a disk drive device in which the inclination of a surface on which a recording disk is placed is reduced including a change with time.

It is explanatory drawing explaining the internal structure of an example of HDD which mounts the sub assembly of the disk drive device of this embodiment. It is a schematic sectional drawing of the brushless motor in the subassembly of the disk drive device of this embodiment. It is explanatory drawing explaining the example of arrangement | positioning of the display mark and weight member in the subassembly of the disk drive device of this embodiment. It is explanatory drawing explaining the shape of the weight member with which the subassembly of the disk drive device of this embodiment is mounted | worn.

Hereinafter, preferred embodiments of the present invention will be described 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.

The sub-assembly of the disk drive device according to the embodiment of the present invention includes, for example, a hard disk drive device that is mounted with a recording disk for magnetically writing / reading data and is driven to rotate (sometimes simply referred to as an HDD or a disk drive device). It can be applied to a brushless motor that is mounted on a motor and drives a recording disk.

FIG. 1 is a top view showing a disk drive device on which a subassembly 100 of the disk drive device according to the present embodiment is mounted. FIG. 1 shows a state in which a top cover (not shown) is removed in order to show the inner structure of the subassembly 100. The subassembly 100 includes a base plate 10 that functions as a base member, and a hub 12. The disk drive device further includes a recording disk 200, a data read / write unit 14, and a top cover (not shown). Hereinafter, the side on which the hub 12 is mounted with respect to the base plate 10 (the upper side in FIG. 1) will be described as the upper side.

The recording disk 200 is placed on the hub 12 and rotates as the hub 12 rotates. The base plate 10 is formed by, for example, molding an aluminum alloy by die casting. The base plate 10 rotatably supports the hub 12 via a bearing described later. The data read / write unit 14 includes a recording / reproducing head 14a, a swing arm 14b, a pivot assembly 14c, and a voice coil motor 14d. The recording / reproducing head 14 a is attached to the tip of the swing arm 14 b and records data on the recording disk 200 and reads data from the recording disk 200. The pivot assembly 14c supports the swing arm 14b with respect to the base plate 10 so as to be swingable around the head rotation axis. The voice coil motor 14 d swings the swing arm 14 b around the head rotation axis, and moves the recording / reproducing head 14 a to a desired position on the recording surface of the recording disk 200. The data read / write unit 14 is configured using a known technique for controlling the position of the head.

FIG. 2 is a cross-sectional view taken along line AA in FIG. The sub-assembly 100 of the disk drive device mounts two 3.5-inch recording disks 200 having a diameter of 95 mm, for example, and rotates them. The diameter of the central hole of each of the two recording disks 200 assumed is 25 mm and the thickness is 1.27 mm.

The subassembly 100 includes a substantially cup-shaped hub 12, a shaft 16, a flange 18, a yoke 20, a cylindrical magnet 22, a base plate 10, a laminated core 24, a coil 26, a sleeve 28, and a counter plate. 30, a lubricant 32, an adhesive 34, and a damping ring 36.

The hub 12 is formed in a convex shape centered on the motor rotation axis R. In the present embodiment, as described above, a case where two recording disks 200 are mounted on the hub 12 is considered, but one recording disk may be used. The central hole of the two recording disks 200 is fitted into the cylindrical outer cylindrical surface 12a of the hub 12 protruding upward. Of the two recording disks 200, the lower recording disk 200a is seated on a seating surface 12b of the surface of the hub 12 projecting radially from the lower end of the outer cylindrical surface 12a. In addition, the diameter of the outer cylinder surface 12a is 25 mm, for example. More precisely, the diameter of the outer cylindrical surface 12a is 24.978 ± 0.01 mm.

An annular first spacer 38 is disposed on the upper surface of the recording disk 200a, and a space is formed between the recording disk 200a and another recording disk 200b. An annular second spacer 40 is disposed on the upper surface of the recording disk 200b, and a clamper 42 is mounted on the upper surface. Therefore, the clamper 42 fixes the two recording disks 200 and the first spacer 38 to the hub 12 in a pressed state via the second spacer 40. The clamper 42 is fixed to the upper surface 12 c of the hub 12 by a plurality of clamp screws 44.

The hub 12 includes a disk-shaped outer extending portion 46 sandwiched between the cylindrical yoke 20 and the recording disk 200a. Further, the hub 12 extends from the end of the outer extending portion 46 toward the base plate 10 in the motor rotation axis R direction. Shaped vertical wall 48. The yoke 20 has a reverse L-shaped section in the direction along the motor rotation axis R, and is formed of a magnetic material such as iron. The yoke 20 is fixed to the lower surface of the outer extending portion 46 and the inner peripheral surface of the vertical wall 48 by using both adhesion and press fitting. On the inner peripheral surface of the vertical wall 48, a convex portion 48a is formed to which the yoke 20 is pressed when the yoke 20 is press-fitted. The convex portion 48 a is an annular portion formed around the motor rotation axis R on the inner wall surface of the vertical wall 48. An adhesive 50 is filled between the lower surface of the outer extending portion 46 and the inner peripheral surface of the vertical wall 48 and the outer peripheral surface of the yoke 20. This is realized by applying an appropriate amount of adhesive 50 to the lower surface of the outer extension 46 and the inner peripheral surface of the vertical wall 48 when the yoke 20 is press-fitted into the hub 12.

On the seating surface 12b of the hub 12, which is the upper surface of the extended portion 46, a raised portion 52 protruding upward is formed in order to seat the recording disk 200a. The raised portion 52 is formed in an annular shape around the motor rotation axis R, and at least the surface of the raised portion 52 where the recording disk 200a is seated is formed as a smooth curved surface. The cross section of the curved surface is an arc shape, and the recording disk 200a comes into line contact with the seating surface 12b.

Further, a cylindrical magnet 22 is bonded and fixed to the inner peripheral surface of the yoke 20. The cylindrical magnet 22 is made of a rare earth material such as neodymium, iron, or boron, and faces nine salient poles formed on the laminated core 24 in the radial direction. The cylindrical magnet 22 is magnetized for driving with 12 poles in the circumferential direction. The cylindrical magnet 22 is fixed to the hub 12 via the yoke 20.

One end of the shaft 16 is fixed to an opening hole portion 12d provided at the center of the hub 12 by an interference fit. A flange 18 is fixed to the other end of the shaft 16 by an interference fit. The hub 12 may be made of a material having a linear expansion coefficient of about 20 × 10 ⁻⁶ . For example, the hub 12 is formed from an aluminum alloy. The shaft 16 may be made of a material having a linear expansion coefficient of about 10 × 10 ⁻⁶ . For example, the shaft 16 is formed from SUS420J2. That is, the linear expansion coefficient of the hub 12 is about twice the linear expansion coefficient of the shaft 16. The difference in linear expansion coefficient between the hub 12 and the shaft 16 is about 10 × 10 ⁻⁶ . In this case, the linear expansion coefficient of the hub 12 is larger than the linear expansion coefficient of the shaft 16.

The upper surface 10a of the base plate 10 is provided with a protrusion 54 centered on the motor rotation axis R. The outer peripheral surface 56 of the protrusion 54 is a cylindrical side surface with the motor rotation axis R as the center. The sleeve 28 is bonded and fixed to the inner peripheral surface 58 of the protruding portion 54. A shaft 16 is rotatably accommodated in the sleeve 28. A counter plate 30 is bonded and fixed to an end of the sleeve 28 where the flange 18 fixed to the shaft 16 is accommodated.

A lubricant 32 is injected between the shaft 16 and the flange 18 and the sleeve 28 and the counter plate 30. The shaft 16, the flange 18, the lubricant 32, the sleeve 28, and the counter plate 30 constitute a fluid bearing for rotatably supporting the hub 12.

On the inner peripheral surface of the sleeve 28, a pair of herringbone-shaped radial dynamic pressure grooves RB1 and RB2 spaced apart in the vertical direction are formed. A herringbone-shaped first thrust dynamic pressure groove SB1 is formed on the upper surface of the flange 18, and a herringbone-shaped second thrust dynamic pressure groove SB2 is formed on the lower surface of the flange 18. When the HDD is driven, the hub 12 and the shaft 16 are not in contact with the surrounding components in the radial direction and the thrust direction by the dynamic pressure generated in the lubricant 32 in the radial dynamic pressure groove RB and the thrust dynamic pressure groove SB. Supported by

A capillary seal portion 60 is formed on the open end side of the sleeve 28. The capillary seal portion 60 is a portion where the gap between the inner peripheral surface of the sleeve 28 and the outer peripheral surface of the shaft 16 gradually widens upward. The capillary seal portion 60 prevents the lubricant 32 from leaking out by a capillary phenomenon.

The laminated core 24 is composed of an annular portion 24a and nine salient pole portions 24b extending radially outward therefrom. The laminated core 24 is formed by, for example, laminating eight non-oriented electrical steel sheets having a thickness of 0.35 mm and integrating them by caulking, for example. As a manufacturing method of the laminated core 24, first, an electromagnetic steel sheet having a surface subjected to insulation treatment is pressed, and each electromagnetic steel sheet is formed by punching into a desired core shape while forming a half punch. Next, the eight core-shaped electrical steel sheets are integrated by caulking by in-mold caulking using the above-described half punch. After this integrated formation, a surface treatment is performed to prevent peeling of the surface of the laminated core. Various methods can be employed for this surface treatment. For example, a method of attaching an epoxy resin by a method such as spray coating or cationic electrodeposition is preferable in that a uniform coating film can be formed.

A coil 26 is wound around each salient pole portion 24 b of the laminated core 24. A driving magnetic flux is generated along the salient pole portion 24b by passing a three-phase substantially sinusoidal driving current through the coil 26.

The damping ring 36 is a cylindrical member formed of a softer material than the electromagnetic steel plate of the laminated core 24, for example, aluminum that is light and easy to process. The damping ring 36 is located between the laminated core 24 and the protruding portion 54, and is pressed into the annular portion 24a of the laminated core 24 to further fix the individual electromagnetic steel plates of the laminated core 24 in the axial direction. The function of suppressing the vibration of the laminated core 24 in the motor rotation axis R direction is provided.

The operation of the disk drive device configured as described above, that is, the brushless motor will be described. In order to rotate the brushless motor, a three-phase drive current is supplied to the brushless motor. When the drive current flows through the coil 26, a drive magnetic flux is generated along each salient pole portion 24b. The drive magnetic flux and the magnetic field generated by the cylindrical magnet 22 act to generate torque, and the entire rotor including the hub 12 rotates.

Incidentally, the recording disk 200 may be tilted with respect to the base plate 10 in the disk drive device constituted by the brushless motor as described above. As described above, the recording disk 200 is supported by the seating surface 12 b that is an extended portion formed in the hub 12. In this case, the hub 12 may be inclined and fixed with respect to the shaft 16 depending on the joining state of the joint portion between the opening hole portion 12 d of the hub 12 and the shaft 16. In this case, when the hub 12 rotates, the axial height of the seating surface 12b varies in the axial direction in the circumferential direction. In other words, because the seating surface is inclined with respect to the rotation axis, there is a maximum value and a minimum value for the height in the axial direction, and a seating surface tilt that is a difference in height occurs. When the seating surface is inclined, the recording disk 200 is attached with an inclination. When the recording disk 200 is tilted, the recording / reproducing head 14a is tilted and traced on the recording disk 200, and so-called head touch characteristics are deteriorated. When the head touch characteristic is deteriorated, the data read / write error rate is deteriorated.

First, the maximum value and the minimum value of the height in the axial direction of the seating surface 12b and the “sitting surface tilt” based thereon will be considered. When the hub 12 is fixed at a right angle to the shaft 16, the height of the seating surface 12b in the axial direction is substantially the same at any position in the circumferential direction. However, when the hub 12 is inclined with respect to the shaft 16, a portion having the highest axial height (hereinafter referred to as HP) and a portion having the lowest axial height (hereinafter referred to as LP) on the seating surface 12b. And there exists. In general, HP and LP exist at angular positions facing each other across the motor rotation axis R.

In the HDD equipped with the subassembly 100 of the present embodiment, the influence of the seating surface inclination on the data error rate can be obtained by experiments. For example, in the case of a 3.5-inch HDD, the present inventors have found that no significant influence on the error rate is observed when the seating surface inclination value (height difference between HP and LP) is 3 μm or less. Got. That is, in the present embodiment, the maximum allowable value of the seating surface inclination value of the 3.5-inch HDD can be 3 μm. Further, when the seating surface inclination value is 10 μm or less, an experimental result has been obtained that the influence on the error rate can be reduced by providing a weight member which will be described later although it is not within the maximum allowable value. Therefore, the present inventors have verified the structure and manufacturing process of the subassembly 100 in detail. As a result, as one of the causes of the “seat surface inclination”, an aging treatment is performed to remove stress generated when the joint portion between the opening hole portion 12d of the hub 12 and the shaft 16 is fixed by tight fitting. It was found that the thermal expansion that occurred during the process was involved. By applying an aging treatment to at least the joint between the hub 12 and the shaft 16, part of the residual stress at the joint can be released, so that the joint state between the hub 12 and the shaft 16 changes due to the residual stress after assembly. Can be difficult. That is, the possibility of increasing the seating surface inclination as a change with time can be reduced by the aging treatment.

As described above, in the subassembly 100 according to the present embodiment, in order to prevent the seating surface inclination that occurs as a change with time due to the residual stress in the joint portion between the hub 12 and the shaft 16, Aging treatment is applied to the joint. For example, as an aging treatment, the joined shaft 16 and hub 12 are allowed to stand in an atmosphere of 80 to 90 ° C. for 30 to 180 minutes. As a result, a part of the residual stress at the joint portion is released. That is, an increase in the seating surface inclination value due to a change with time can be reduced.

By the way, the opening 12d provided at the center of the hub 12 has to be processed with high accuracy in its cylindrical inner peripheral surface so that a squareness can be obtained when the shaft 16 is fixed. Strictly speaking, irregular surfaces such as a portion that is not a perfect circle and a portion that is not flat in the axial direction exist on the inner peripheral surface. For this reason, when the opening hole portion 12d is thermally expanded during the aging treatment, a portion of the irregular surface that is a gap until then (a non-pressure contact portion) is newly brought into a pressure contact state or a pressure contact state until then. The part which maintains is generated at random. At this time, the stress at which the opening hole portion 12d tightens the shaft 16 concentrates on the pressure contact portion generated by the expansion, and the portion is crushed. As a result, irregular and irreversible deformation occurs in the entire joint portion of the opening hole portion 12d, and the joining state of the opening hole portion 12d and the shaft 16 changes. In this state, when the aging treatment portion is returned to room temperature and the expanded portion contracts, the expanded portion is plastically deformed before the aging treatment. That is, a gap is generated between the shaft 16 and the shaft 16. As a result, in the joint relationship between the opening hole 12d and the shaft 16, there is a high possibility that the right angle state is worse than before the aging treatment. In other words, the seating surface inclination value of the seating surface 12b may increase.

Therefore, in the subassembly 100 of the present embodiment, the seating surface inclination value of the recording disk 200 determined by the coupling state of the opening 12d of the hub 12 and the shaft 16 is not more than a predetermined maximum allowable value. The opening hole portion 12d is configured to maintain a pressure contact state with the shaft 16 at a processing temperature when an aging treatment is performed on at least a joint portion between the hub 12 and the shaft 16. As described above, by allowing the processing temperature during the aging treatment to maintain the pressure contact state in the entire joint portion, it is easy to avoid stress concentration due to expansion even if there is an irregular surface in the opening hole portion 12d. Therefore, it can suppress that the surface of the opening hole part 12d deform | transforms. That is, at the treatment temperature of the aging treatment, the opening hole 12d is not deformed, and even when the temperature returns to the room temperature after the treatment, it is difficult to produce a non-pressure contact surface that increases the seating surface inclination value.

As described above, as one method of maintaining the pressure contact state of the opening hole portion 12d with the shaft 16 at the treatment temperature of the aging treatment, the surface roughness that is the degree of the irregular surface of the opening hole portion 12d is aged. The diameter is configured to be substantially smaller than the difference between the diameter of the opening hole 12d and the diameter of the shaft 16 at the processing temperature. For example, when the difference in diameter between the opening hole 12d and the shaft 16 at the aging treatment temperature is 4 μm, the surface roughness of the opening hole 12d is set to a range of 2 μm or less. By doing in this way, it is suppressed that the press-contact force which generate | occur | produced between the opening hole part 12d and the shaft 16 in the process temperature of an aging treatment falls with the clearance gap produced by the surface roughness of the opening hole part 12d. The That is, the opening hole portion 12d can substantially maintain the pressure contact state with the shaft 16 even at the aging treatment temperature.

In addition, it is desirable to confirm whether or not the opening hole portion 12d substantially maintains the pressure contact state with the shaft 16 at the treatment temperature of the aging treatment. For example, when the temperature of the hub 12 is set to the aging treatment temperature and an axial separation test load is applied between the shaft 16 and the hub 12, the connection between the shaft 16 and the hub 12 can be substantially maintained. The relationship between the force and the seating surface inclination value after aging treatment is determined by experiment. For example, in the present embodiment, when the diameter of the shaft 16 is 4 mm, a force of 3N, for example, is applied as a separation test load between the shaft 16 and the hub 12 in the axial direction. At this time, if the shaft 16 and the hub 12 have a coupling force that substantially maintains the coupling between the shaft 16 and the hub 12, the seating surface inclination value after the aging treatment is a predetermined maximum allowable value (for example, 3 μm). The following was confirmed. In other words, the shape of the opening hole 12d is such that, for example, 3N is added as a separation test load in the axial direction between the shaft 16 and the hub 12 so as to have a coupling force that maintains a substantial coupling state with the shaft 16. The size, surface roughness, material, etc. can be determined.

Incidentally, non-standard products may be produced in which the seating surface inclination value subjected to the aging treatment exceeds the predetermined maximum allowable value (for example, 3 μm). In this case, a correction process for correcting the axial dimension of the seating surface 12b may be performed so that the seating surface inclination value is equal to or less than a predetermined maximum allowable value. For example, the subassembly 100 is fixed, and a force in a direction in which the seating surface inclination value is reduced is applied to the hub 12 to reduce the seating surface inclination value. This operation is desirably repeated until the seating surface inclination value is equal to or less than a predetermined maximum base maximum allowable value.

On the other hand, in the production process of the disk drive device, it is necessary to confirm that the seating surface inclination value of the subassembly 100 is within the maximum allowable value in order to maintain the predetermined quality. However, a non-standard product may be mistakenly mixed into the sub-assembly 100 within the standard after confirmation. If the recording disk 200 or the like is mounted on the non-standard subassembly 100 as described above and the disk drive device is produced, the error rate of the disk drive device may decrease. In such a case, the repair takes a great deal of time. Therefore, it is desirable for the subassembly 100 to clarify whether or not the seating surface inclination value has been confirmed and whether or not it is within the standard.

Therefore, in this embodiment, a display mark corresponding to the seating surface tilt value is attached to any position of the subassembly 100 so that it can be determined whether or not the seating surface tilt value has been confirmed. By attaching such display marks, even if non-standard products are mixed with non-standard products, they can be easily identified.

The display mark may be displayed at any position on the subassembly 100. For example, it is preferable in that it can be easily discriminated when displayed on the upper surface 12c of the outer cylinder portion of the hub 12. This display mark may be displayed corresponding to the angular position of the HP. For example, displaying at the HP angular position on the upper surface 12c of the hub 12 is preferable in that it can be discriminated even after the recording disk 200 is mounted. FIG. 3 shows an example in which the display mark 300 in the present embodiment is displayed corresponding to the HP angular position of the upper surface 12 c of the outer cylinder portion of the hub 12. By attaching the display mark 300, it can be easily understood that the seating surface inclination value has been confirmed. Further, it is easy to know that the position of the display mark 300 is the HP position, and the HP position can be easily set based on the position of the display mark 300 even when the seating surface inclination value needs to be corrected in the post-process or repair work. Therefore, the correction work can be performed efficiently. The display mark 300 may be displayed when the shaft 16 is coupled to the opening 12d of the hub 12. That is, the display mark 300 can be displayed continuously in the operation of coupling the shaft 16 to the opening 12 d of the hub 12. The display mark 300 may be displayed before the aging treatment. In this case, it is advantageous in that the operation of applying the display mark 300 is easy. The display mark 300 may be displayed after the aging process. This is advantageous in that the display mark 300 is not affected by discoloration or the like due to the aging process. Although FIG. 3 shows the simplest black dot mark as the display mark 300, the display mark 300 may have other information in addition to information such as confirmation of the seating surface inclination value and HP position. . For example, the display mark 300 may be provided with information such as a specific magnitude of the seating surface tilt value and whether or not an operation for correcting the seating surface tilt value has been performed. Such information can be determined in advance corresponding to, for example, the shape and color of the display mark 300 and the number of applied marks. For example, the external dimension of the display mark 300 can be small when the seating surface tilt value is small, and can be large when the seating surface tilt value is large.

Next, a configuration for reducing the influence on the error rate of data even when the seating surface inclination value is outside the standard exceeding 3 μm which is the maximum allowable value will be described with reference to FIGS. In this case, the recording disk 200 is mounted with an inclination. As described above, in the disk drive device, the recording / reproducing head 14a traces over the recording disk 200 rotating at high speed through a slight gap. In FIG. 3, for the sake of easy understanding, the situation where the recording / reproducing head 14a is located in the area farthest from the recording disk 200 (LP corresponding position) and the situation located in the closest area (HP corresponding position) are simultaneously expressed. As shown, two recording / reproducing heads 14a are drawn on the left and right.

When the recording disk 200 rotates, an air flow in the rotational direction is generated due to the viscosity of the surrounding air. When the recording disk 200 is inclined, the recording / reproducing head 14a depicted on the left side of the motor rotation axis R in FIG. 3 applies an outward force as indicated by an arrow M in FIG. On the other hand, the recording / reproducing head 14a depicted on the right side of the rotation axis in FIG. 3 applies an inward force as indicated by an arrow N in FIG. As a result, the recording / reproducing head 14a may be off-tracked corresponding to the inclination of the recording disk 200 (inclination based on the seating surface inclination value). Corresponding to this off-track, the gap 250 between the recording disk 200 and the outer cylindrical surface 12a is preliminarily moved to one side and mounted. For example, the recording disk 200 is mounted so that the gap on the HP side (right side of the motor rotation axis R in FIG. 3) is minimized and fitted to the outer cylindrical surface 12a of the hub 12. By mounting the recording disk 200 in this way, it is possible to reduce the influence of off-track caused by the inclination of the recording disk 200.

However, as described above, when the recording disk 200 is offset and fitted to the outer cylindrical surface 12a of the hub 12, the center of gravity of the recording disk 200 is deviated from the motor rotation axis R to the opposite side of the HP. For this reason, the unbalance of the entire rotating body increases, and vibration due to the unbalance may further occur when the recording disk 200 rotates. Therefore, in the present embodiment, the weight member 400 corresponding to the inclination value of the seating surface is attached to the hub 12 so as to suppress the vibration of the recording disk 200. The weight member 400 can be mounted at a position corresponding to the HP, for example. As a result, the external force by the weight member 400 acts in the direction of decreasing the axial height at the HP position, and the vibration of the recording disk 200 in the motor rotation axis R direction can be reduced.

The weight member 400 may be attached to any location on the hub 12 as long as it corresponds to the HP. For example, it is preferable to attach to the inner peripheral side of the outer extension 46 of the hub 12 because the possibility that the weight member 400 is detached by centrifugal force when the hub 12 rotates is reduced. Further, a groove portion extending in the circumferential direction on the inner peripheral side of the outer extension portion 46 of the hub 12 and having an opening on the motor rotation shaft R side may be formed and attached thereto. In this case, it is preferable in that the weight member 400 is more difficult to come off.

Further, as shown in FIG. 3, the hub 12 is formed with a groove portion 12e extending in the circumferential direction at a position overlapping the outer extension portion 46 in the motor rotation axis R direction, and the weight member 400 is mounted in the groove portion 12e. It may be. In this case, since the groove 12e is close to the opening on the inner side of the hub 12, it is preferable in that the work of attaching the weight member 400 is easy.

The weight member 400 can have various shapes. For example, as shown in FIG. 4, the weight member 400 has a mass part 400a having a predetermined mass at the center, and has a substantially semicircular spring part 400b that holds the mass part 400a in the groove part 12e on both sides thereof. You may comprise. By providing the spring portion 400b, the weight member 400 can be easily slid while being held in the groove portion 12e by the elasticity of the spring portion 400b. As a result, the insertion operation into the groove 12e and the determination operation of the attachment position are facilitated.

In the present embodiment, the bearing unit has a pair of radial dynamic pressure grooves RB1 and RB2. The weight member 400 may be attached to a position between the radial dynamic pressure grooves RB1 and RB2 in the motor rotation axis R direction of the inner peripheral portion of the hub 12. By disposing the weight member 400 at this position, an effect of minimizing the presence of the weight member 400 on the dynamic pressure generation balance of the radial dynamic pressure grooves RB1 and RB2 can be expected.

Further, the weight member 400 may be attached at a position closer to the motor rotation axis R than the outer cylindrical surface 12a of the hub 12 in the radial direction of the hub 12. Mounting on the inner side of the outer cylindrical surface 12a of the hub 12 is advantageous in that the thickness of the hub 12 in the radial direction can be maintained thick, so that the rigidity is not lowered. Further, the weight member 400 may be attached to a position outside the outer periphery of the bearing unit in the radial direction of the hub 12. Arranging at such a position is advantageous in that the work for attaching the weight member 400 is wide and the attachment work is easy.

When attaching the weight member 400, it may not be attached at a desired position in the first operation. In the present embodiment, as described above, the weight member 400 has the spring portion 400b. The weight member 400 is slidable within the groove 10e by using the elastic force of the spring part 400b, and is attached by being stopped at a desired position. However, if the weight member 400 is moved from a desired position by the rotation of the hub 12, the above-described vibration suppression effect may be reduced. Therefore, the weight member 400 of the present embodiment has a mounting force that substantially maintains the stopped state at the position where the hub 12 is mounted in the groove 12e both when the hub 12 starts rotating and when the hub 12 stops rotating. It is comprised so that it may have. For example, the weight member 400 desirably determines the spring property, shape, length, and the like of the spring portion 400b in order to obtain the mounting force. This mounting force is preferably determined in advance by taking into account the inertial force received at the start and stop of rotation by a test.

Further, the weight member 400 may be removably attached. For example, the elastic force of the spring part 400b can be used also at the time of attachment / detachment. By making it attachable and detachable in this manner, the weight member 400 can be adjusted later and the weight member 400 can be easily replaced.

Incidentally, in the present embodiment, the diameter of the opening hole 12d of the hub 12 is formed to be about 4 mm. The diameter of the shaft 16 is slightly larger than the diameter of the opening hole 12d of the hub 12. The shaft 16 is inserted into the opening hole portion 12d of the hub 12 and fixed by an interference fit. Moreover, you may use an adhesive agent together auxiliary as needed. However, if the hub 12 is inserted in a state where the diameter of the opening hole 12d of the hub 12 is smaller than the diameter of the shaft 16, the friction resistance during insertion is large and the surface of the opening hole 12d is not uniform. May be tilted and fixed. Therefore, in the present embodiment, the shaft 16 may be inserted into and fixed to the opening hole 12d in a state where the diameter of the opening hole 12d of the hub 12 is larger than the diameter of the shaft 16. Specifically, the opening hole portion 12 d of the hub 12 is heated and thermally expanded, so that the diameter of the opening hole portion 12 d is larger than the diameter of the shaft 16. In this state, the shaft 16 is inserted and fixed by returning to room temperature. As a result, the hub 12 is prevented from being inclined and fixed to the shaft 16. Further, since it is not press-fitted, it is preferable in that the deformation of the hub 12 and the occurrence of residual stress can be reduced.

The heating temperature of the opening hole 12d can be obtained by calculation and experiment using parameters such as the diameter of the opening hole 12d, the linear expansion coefficient of the base material constituting the hub 12, and the diameter of the shaft 16. For example, if the heating temperature of the opening hole 12d when inserting the shaft 16 is higher than the aging treatment temperature by 50 ° C. or more, the insertion of the shaft 16 is easy and the increase in the seating surface inclination value during the aging treatment can be reduced. The inventors have obtained experimental results that are advantageous in terms of point. In addition, the inventors have obtained an experimental result that it is advantageous that the heating temperature of the opening hole portion 12d is 150 ° C. or less, which is less likely to cause deformation or discoloration in the vicinity of the opening hole portion 12d.

For example, in one example of the present embodiment, the diameter of the shaft 16 at 25 ° C. is 2 to 9 μm larger than the diameter of the opening hole 12d, the aging treatment temperature is 80 ° C. to 90 ° C., and the opening when the shaft 16 is inserted is used. The heating temperature of the hole 12d is set to 120 to 140 ° C. According to this setting, the inventors have obtained an experimental result that it is unlikely that a non-standard product having a seating surface inclination value subjected to aging treatment exceeding a predetermined maximum reference value is produced.

Incidentally, in the production process of the disk drive device, the subassembly 100 may accidentally collide with production equipment. At this time, scratches and deformation may occur in the outer extension 46 of the hub 12. If the extended portion 46 is deformed, the mounting stability of the recording disk 200 is impaired, and the possibility that the recording disk 200 is placed in an inclined manner increases. Therefore, in the present embodiment, the outer flange portion of the outer extending portion 46 is closer to the motor rotation shaft R side than the circumscribed surface that circumscribes the constituent parts of the hub 12 existing on one and the other side of the outer flange portion in the axial direction. It is configured to be located. As an example, as shown in FIG. 2, the outer flange portion 46 a of the outer extension portion 46 is configured to be disposed radially inside the circumscribed conical surface 500 that circumscribes the outer shape of the hub 12. That is, in FIG. 2, a circumscribed conical surface 500 that circumscribes the outer shape of the hub 12 and decreases in diameter toward the hub 12 from the base plate 10 side is assumed. The outer flange portion 46a is configured so as to be included in the radial inner side of the circumscribed conical surface 500 closest to the outer flange portion 46a and not to contact. As a result, when the subassembly 100 collides with the flat part of the production facility, any of the circumscribed conical surfaces 500 collides. Therefore, the possibility that the outer flange portion 46a directly collides with the production facility or the like and is deformed is reduced. As a result, it is possible to prevent the recording disk 200 from being inclined and placed due to a collision or the like. It should be noted that the outer flange portion 46 a only needs to be retracted toward the motor rotation axis R direction side from other components, and may not be a conical surface like the circumscribed conical surface 500. For example, a cylindrical surface that encloses the outer flange portion 46a may be used, and similar effects can be obtained.

Although the present embodiment has been described mainly for use in HDDs, the present invention is not limited to this. For example, a brushless motor having the structure shown in FIG. 2 may be manufactured, and the brushless motor may be mounted on an optical disk recording / reproducing device such as a CD (Compact Disc) device or a DVD (Digital Versatile Disc) device.

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.

According to the present invention, it can be used for a subassembly of a disk drive device such as a hard disk drive.

DESCRIPTION OF SYMBOLS 12 Hub 12b Seating surface 12d Opening hole part 12e Groove part 16 Shaft 28 Sleeve 46 Outward extension part 46a Outer part RB Radial dynamic pressure groove SB Thrust dynamic pressure groove 58 Inner peripheral surface 100 Subassembly 200 Recording disk 300 Display mark 400 Weight member.

Claims

A base member;
A hub on which the recording disk should be placed;
A shaft coupled to an opening hole in the center of the hub;
A bearing unit that supports the shaft so as to be rotatable relative to the base member;
With
The hub includes an outer cylinder portion that extends in the axial direction of the bearing unit to hold the recording disk, and an outer extension portion that is connected to the outer cylinder portion and extends outward in the radial direction of the recording disk. And a disc seating surface formed on the extension part,
The opening hole is set so that an inclination value of the disc seating surface determined by a coupling state of the opening hole portion of the hub and the shaft with respect to a surface orthogonal to the axial direction is equal to or less than a predetermined maximum allowable value. The disk drive device sub-assembly is characterized in that the portion is configured to maintain a pressure contact state with the shaft at a processing temperature when an aging treatment is performed on at least a coupling portion of the hub and the shaft.
The opening hole portion maintains the pressure contact state by making the surface roughness of the opening hole portion smaller than a diameter difference between the diameter of the opening hole portion and the diameter of the shaft at the temperature of the aging treatment. The sub-assembly of the disk drive device according to claim 1.
The opening hole has a coupling force that maintains a substantial coupling state with the shaft when the axial separation test load is applied between the shaft and the hub at the temperature of the aging treatment. 3. A sub-assembly of a disk drive device according to claim 1, wherein the shaft is coupled so as to have a structure.
After the hub is subjected to the aging process, the hub is subjected to a correction process for correcting the axial dimension of the disk seating surface so that the inclination value of the disk seating surface is equal to or less than a predetermined maximum allowable value. The sub-assembly of the disk drive device according to any one of claims 1 to 3, wherein the sub-assembly is provided.
5. A sub-assembly of a disk drive device according to claim 1, further comprising a display mark indicating an inclination value of the disk seating surface.
6. The sub-assembly of a disk drive device according to claim 5, wherein the display mark is displayed on an upper surface of the outer cylinder portion.
7. The sub-assembly of a disk drive device according to claim 5, wherein the display mark has a shape corresponding to an inclination value of the disk seating surface.
The sub-assembly of a disk drive device according to any one of claims 5 to 7, wherein the display mark is arranged corresponding to the highest axial position of the disk seating surface.
9. The sub-assembly of a disk drive device according to claim 5, wherein the display mark is displayed when the shaft is coupled to the opening hole.
9. The sub-assembly of a disk drive device according to claim 5, wherein the display mark is displayed after the aging treatment.
11. The disk drive according to claim 5, wherein the display mark has information indicating whether or not an operation of correcting a seating surface inclination value of the disk seating surface has been performed. Device subassembly.
12. The sub-assembly of a disk drive device according to claim 1, wherein the hub includes a weight member corresponding to an inclination value of the disk seating surface.
13. The sub-assembly of a disk drive device according to claim 12, wherein the weight member is attached to a groove portion that extends in a circumferential direction of an inner peripheral surface of the hub and opens toward a rotating shaft side of the hub.
14. The sub-assembly of a disk drive device according to claim 12, wherein the weight member is attached at a position overlapping with the extension portion in the axial direction.
The weight member is slidably mounted in the groove, and is substantially in a stopped state at the position where it is mounted in the groove both when the hub starts rotating and when the hub stops rotating. 15. The sub-assembly of a disk drive device according to claim 13, wherein the mounting force is maintained to be maintained.
16. The weight member according to any one of claims 13 to 15, wherein the weight member includes a mass portion having a predetermined mass at a center portion, and substantially semicircular spring portions on both sides thereof. A sub-assembly of the disk drive device according to 1.
The disk drive device sub-assembly according to any one of claims 13 to 16, wherein the weight member is detachably attached.
18. The shaft according to claim 1, wherein the shaft is coupled by being inserted into the opening hole in a state where the diameter of the opening hole is larger than the diameter of the shaft. Disk drive subassembly.
The outer flange portion of the outer extension portion is located closer to the rotating shaft side of the hub than a circumscribed surface circumscribing a constituent part of the hub existing on one and the other side of the outer flange portion in the axial direction. The sub-assembly of the disk drive device according to any one of claims 1 to 18.
The outer flange portion is enclosed on the radially inner side of the circumscribed conical surface closest to the outer flange portion, out of the circumscribed conical surfaces that circumscribe the outer shape of the hub and reduce the diameter from the base plate side toward the hub direction. The sub-assembly of the disk drive device according to claim 19, wherein the sub-assembly is configured so as not to contact with each other.