JP2006331558A - Spindle motor, recording disk driver, manufacturing method of hub of spindle motor, recording disk drive, and manufacturing method of recording disk drive - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a spindle motor where the rotation center of a recording disk and that of a rotor hub are made to coincide inexpensively and precisely; to manufacture the rotor hub used for the spindle motor; and to manufacture a recording disk driver provided with the rotor hub. <P>SOLUTION: On the upper end face of the rotor hub 70, a hole 74 which is coaxial with the center axis of an outer peripheral surface 71 and which has a diameter shorter than the diameter of the radial-direction of the shaft 30 is formed. The center axis of the hole 74 and that of an axial-direction projecting part 141 of a disk-mounting tool 140 can easily made to coincide with each other. A circular projecting part 142 holding a recording disk 150 is provided coaxially with the hole 74, so that coaxialness of the recording disk 150 and the hole 74 is made to coincide precisely. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a spindle motor, a recording disk drive device, a spindle motor hub manufacturing method, a recording disk drive device, and a manufacturing method thereof.

<1. Recent trends>
In recent years, the recording capacity per unit area of a disk-shaped recording medium has increased dramatically. As a result, the processing accuracy of each component constituting the recording disk drive device, in particular, the component related to the rotation of the recording disk, is drastically increased as compared with the past. On the other hand, the price of the recording disk drive is declining, and the price of the spindle motor mounted on it is also declining.

<2. Spindle motor structure>
FIG. 7 shows a spindle motor used in a conventional recording disk drive device. The spindle motor 300 includes a substantially cylindrical shaft 310, a rotor hub 320 that is connected to the upper end of the shaft 310 and on which a recording disk (not shown) is placed, and the rotor hub 320 attached to the rotor hub 320. And a bearing 340 that rotatably supports the shaft 310. The drive unit includes a stator 350 composed of a plurality of coils, and a rotor magnet 360 that is rotated by a field magnetic field generated by the stator 350.

<3. Conventional structure>
In order to improve the writing and reading accuracy of the recording disk drive device, it is desirable to make the rotation center of the recording disk coincide with the rotation center of the rotor hub 320 as much as possible.

  The spindle motor shown in FIG. 1 includes a shaft hole 311 having a cylindrical or polygonal inner wall at the upper end of a shaft 310. The shaft 310 is fitted into a through hole 321 provided in the rotor hub 320.

  In the case of this structure, the rotation center of the recording disk is positioned using the shaft hole 311 as a reference for rotation of the rotor hub 320. This rotation center positioning method is as described in Patent Document 1. In other words, the recording disk is placed on the rotor hub 320 and positioned using a jig based on the shaft hole 311.

US Pat. No. 6,707,639

  However, the conventional spindle motor 300 has the following problems to be overcome. As the material constituting the shaft 310, a very hard material is used in consideration of slidability with the bearing, wear resistance, and the like. Therefore, it is very difficult to form the above-described shaft hole 311 with high accuracy. As a result, if the shaft 310 in which the shaft hole 311 is formed is used, the cost cannot be reduced.

  In addition, processing tolerances between the inner peripheral surface of the through hole of the rotor hub 320 and the outer peripheral surface of the shaft 310 are accumulated due to the fitting, no matter how highly accurate. Therefore, it is difficult to ensure the coaxiality between the central axis of the through hole 321 of the rotor hub 320 and the central axis of the shaft hole 311.

  The subject of this invention is made | formed in view of the conventional problem as mentioned above. That is, to obtain a spindle motor in which the rotation center of the recording disk and the rotation center of the rotor hub coincide with each other at low cost and with high accuracy. Another object is to manufacture a rotor hub used in the spindle motor. Furthermore, it is to manufacture a recording disk drive device including the rotor hub.

  According to a first aspect of the present invention, there is provided a substantially cylindrical shaft body disposed coaxially with the rotation center axis, and a rotor hub that covers the upper end surface of the shaft body and is substantially coaxial with the rotation center axis. In the spindle motor, the rotor hub is formed concentrically with the rotation center axis, and the center of the disk-shaped recording disk. A cylindrical outer peripheral surface into which the hole is fitted, and a plane substantially orthogonal to the rotation center axis, a disk placement surface on which the recording disk is placed, and the rotation center axis are formed concentrically, An axial direction fitting hole having a cylindrical inner peripheral surface to which the shaft body is fixed, and the shaft body is fitted and fixed to the fitting hole leaving an upper part of the fitting hole, During the rotation of the rotor hub, the fitting hole and the end face of the shaft body Wherein the circular recess that opens to the upper surface of the concentric is formed with.

  According to claim 1 of the present invention, by providing a circular recess in the upper part of the fitting hole between the shaft body and the rotor hub, the circular recess is located at the center of the center hole of the recording disk when the recording disk is placed. It can be used to align the coaxial with a jig or the like. Therefore, the coaxiality between the recording disk and the rotor hub can be improved. Conventionally, a bag-like hole has been provided on the shaft body side so that the recording disk can be placed on the same axis. However, the shaft body has high hardness, and there is a drawback that the life of a tool for processing this is reduced. It was. However, in the present invention, since it is not necessary to form a hole, there is no need to worry about tool life without using a tool. Therefore, the equipment cost can be reduced, and the man-hour for machining the hole in the shaft body can be reduced, so that the price of the spindle motor can be reduced.

  According to a second aspect of the present invention, according to the first aspect, a hole having a diameter smaller than a diameter in a radial direction of the shaft body is provided in a part of the upper side of the fitting hole.

  According to the second aspect of the present invention, since the hole is formed on the rotor hub side having low hardness without forming the hole in the shaft body having high hardness, the life of the tool used for drilling is not reduced. Further, it takes a lot of time to make a hole in a shaft having a high hardness. However, since it takes only a short time to make a hole in a rotor hub having a low hardness, the process time can be reduced. Therefore, the production efficiency is improved, so that the price of the spindle motor can be reduced.

  According to a third aspect of the present invention, a recording disk having a magnetic recording layer, a magnetic head for recording information on the magnetic recording layer and reproducing information recorded on the magnetic recording layer, and the magnetic head A moving means for moving the magnetic disk with respect to the recording disk and a spindle motor according to any one of claims 1 and 2 for rotating the magnetic disk.

  According to the third aspect of the present invention, since the spindle motor according to the first and second aspects is mounted, the coaxial accuracy between the rotor hub and the recording disk is good, and there is no read / write error by the magnetic head. A high recording disk can be provided.

  According to a fourth aspect of the present invention, there is provided a method for placing a recording disk on a spindle motor equipped with a rotor hub arranged coaxially with a rotation center axis by using a disk placing jig, A rotation center axis is formed concentrically, a cylindrical outer peripheral surface into which a center hole of a disk-shaped recording disk is fitted, and a plane substantially orthogonal to the rotation center axis, on which the recording disk is placed A disk mounting surface, an axial fitting hole formed concentrically with the rotation center axis and having a cylindrical inner peripheral surface to which the shaft body is fixed, and the rotation hole of the spindle motor in the fitting hole The shaft body is formed into a circular recess formed by fitting with the upper part of the fitting hole, and the fitting hole formed in the rotor hub is used for positioning the disk mounting jig, and The disk mounting jig is A step of positioning the recording disk with respect to the disk mounting jig; and a step of positioning the recording protrusion with the circular shape of the rotor hub. A step of fitting into the recess, and a step of placing the recording disk on the rotor hub.

  According to the fourth aspect of the present invention, the center axis of the rotor hub and the disk mounting jig can be easily fitted by fitting the circular recess formed by the rotor hub and the shaft body and the protrusion of the disk mounting jig. Can be made to coincide with the central axis. As a result, the center of the recording disk positioned on the disk mounting jig and the center axis of the rotor hub can be easily aligned. As a result, it is possible to provide a spindle motor and a recording disk driving device with high coaxial accuracy between the recording disk and the rotor hub.

  According to the fifth aspect of the present invention, the mounting surface that is substantially orthogonal to the rotation center axis on which the recording disk is mounted and the center axis that is a specific axis with respect to the predetermined member are determined, and the center axis And a hole having a cylindrical inner peripheral surface centered on the central axis. A processing method of a rotor hub of a spindle motor comprising: At least one rotatable holding tool for holding the base material and a cutting tool for cutting the base material are used, and the base material is arranged so that the rotation center axis of the holding tool and the central axis are substantially coaxial. A step of holding, and a step of cutting the outer peripheral surface and the hole in a state of being held by one of the holders while rotating the holder with respect to the cutting tool. .

  According to claim 5 of the present invention, it is possible to perform processing accurately with respect to the rotation of the holder by securing the coaxial of the holder and the base material in advance. Furthermore, since the outer peripheral surface and the hole are processed while being held by the holder, the center of the outer peripheral surface and the center of the hole can be matched. As a result, since the disk mounting jig is fitted into the hole, the coaxial accuracy is improved, and the concentric accuracy between the center of the recording disk held by the disk mounting jig and the center of the hole is improved. Therefore, it is possible to provide a recording disk drive device with high read / write accuracy that is free from deviation between the rotation center of the rotor hub and the rotation center of the recording disk.

  According to the present invention, it is possible to obtain a spindle motor in which the rotation center of the recording disk and the rotation center of the rotor hub coincide with each other at low cost and with high accuracy. Further, a rotor hub used for the spindle motor can be manufactured. Furthermore, a recording disk drive device including the rotor hub can be manufactured.

<1. Overall Structure of Recording Disk Drive>
FIG. 1 is a schematic axial sectional view showing an embodiment of a recording disk drive apparatus according to the present invention.

  The recording disk drive device 1 includes a housing 2 having a substantially rectangular shape, and the inside of the housing 2 forms a clean space that is extremely free of dust, dust, and the like, and an annular recess 2a is formed therein. A spindle motor 5 on which a disc-shaped recording disk 3 for recording information is mounted by a clamp 4 serving as a recording disk mounting holder is disposed. The housing 2 and the base 10 described later may be integrally formed.

  A head moving mechanism 6 for reading / writing information from / to the hard disk 3 is disposed inside the housing 2. The head moving mechanism 6 includes a magnetic head 6 a for reading / writing information on the hard disk 3, and the magnetic head 6 a. The supporting arm 6b and the magnetic head 6a and the arm 6b are configured by an actuator unit 6c that moves the arm 6b to a required position on the hard disk 3.

  By applying the spindle motor of the present invention as the spindle motor 5 of such a recording disk drive device 1, the recording disk 1 can secure a sufficient function to improve the coaxial accuracy with respect to the rotation axis. It is possible to provide a recording disk drive device with high reliability and durability of the drive device 1.

<2. Overall structure of spindle motor>
FIG. 2 is a schematic axial sectional view showing an embodiment of a spindle motor according to the present invention.

  The base 10 is a conductive member such as aluminum coated with an insulating film, and has a lower annular recess 11. Further, a radially enormous portion 12 extending outward in the radial direction is formed on the upper end surface of the lower annular recess 11. In addition, an annular protrusion 13 having a through hole in the center is formed at the center of the lower annular recess 11.

  On the inner peripheral surface of the annular protrusion 13 of the base 10, the outer peripheral surface has a substantially cylindrical shape, and a bearing sleeve 20 formed of copper or the like is fixed by adhesion or the like. Further, the inner peripheral surface is formed with a portion having a large inner diameter at three locations, which are a first inner diameter portion 21, a second inner diameter portion 22 and a third inner diameter portion 23, which are in order of decreasing inner diameter from the upper side. A shaft 30 formed of a hard member such as stainless steel is disposed so as to be able to pass through the first inner diameter portion 21 so as to face the first inner diameter portion 21 in a radial direction. Further, a thrust plate 40 formed of stainless steel or the like is fixed to the lower end portion of the shaft 30 so as to face the second inner diameter portion 22 in the radial direction with a small gap. Further, a plate 50 formed of stainless steel or the like is fixed to the third inner diameter portion 23 by bonding or the like so as to face the lower end surface of the shaft 30 with a slight gap in the axial direction. These minute gaps are filled with the lubricating fluid substantially without interruption, and the radially opposed surfaces of the bearing sleeve 20 and the shaft 30, the axially opposed surfaces of the bearing sleeve 20 and the thrust plate 40, and the thrust. A hydrodynamic bearing is formed on the axially opposed surfaces of the plate 40 and the plate 50 and favorably supports the shaft 30 and the thrust plate 40 that are rotating bodies.

  Further, a step portion 13a having a lower outer diameter is formed on the outer peripheral surface of the annular projection 13 of the base 10, and the stator 13 is in contact with the step portion 13a and the outer peripheral surface above the step portion 13a. 60 is fixed by adhesion or the like. In the stator 60, a ring-shaped core back portion 61 and teeth portions 62 projecting radially outward at equal intervals in the circumferential direction at the outer edge portion of the core back portion 61 are formed of a thin plate such as a silicon steel plate. And a winding 63 that winds around the teeth portion 61 formed by laminating the thin plates.

  On top of the shaft 30, a recording disc (not shown) is mounted and a rotor hub 70 that rotates is fixed by adhesive press fitting or the like. The rotor hub 70 is formed of a member having low hardness such as aluminum or free-cutting stainless steel, and an outer peripheral surface 71 having a diameter substantially the same as the inner diameter of the recording disk is formed. Further, on the lower side of the outer peripheral surface 71, a disk mounting surface 72 is formed which is a flat surface extending outward in the radial direction and on which a recording disk is mounted. Further, a cylindrical portion 73 that hangs downward is formed on the outer edge portion of the disk mounting surface 72. An annular rotor yoke 80 made of iron is fixed to the inner peripheral surface of the cylindrical portion 73 by bonding or the like, and a rotor magnet 90 is fixed to the inner peripheral surface of the rotor yoke 80 by bonding or the like. The inner peripheral surface of the rotor magnet 90 and the outer peripheral surface of the tooth portion 61 of the stator 60 are opposed to each other through a gap in the radial direction, and a magnetic field is generated by energizing the winding 63 of the stator 60. Due to the interaction between the magnetic field and the rotor magnet 90, a rotational force is generated and rotationally driven.

<3. Main part>
FIG. 3 is an enlarged view of a dotted circle in FIG. 2 showing a fitting portion between the shaft 30 and the rotor hub 70 which are main portions according to the present invention.

  The rotor hub 70 is formed with a hole 74 smaller than the diameter of the shaft 30 and a fitting hole 75 that is continuous with the hole 74 and is substantially the same as the diameter of the shaft 30 that fits the shaft 30. Yes. As a result, a stepped portion 76 is formed at the connecting portion between the hole 74 and the fitting hole 75, and the shaft 30 is fixed to the fitting hole 75 so as to contact the stepped portion 76. As a result, the shaft 30 and the rotor hub 70 can be easily positioned in the axial direction, so that the working efficiency can be improved and the positioning jig necessary for the fitting can be eliminated.

  An annular inclined surface 74 a is formed at the opening of the hole 74. Thus, when the disk mounting jig 140, which will be described later, is inserted into a protruding portion 141, the inclined surface 74a can guide the protruding portion 141 to the axial center of the hole 74, and the disk mounting jig 140 can be easily operated. The center axis and the center of the hole 74a can be aligned.

<4. Processing method of rotor hub>
FIG. 4 is a schematic view showing a processing device for the outer peripheral surface 71, the disk mounting surface 72, and the hole 74 of the rotor hub 70 according to the present invention. Moreover, the dotted line in a figure shows the rotation center axis | shaft of a holder, and the arrow around a dotted line shows a rotation direction.

  The processing apparatus 100 includes a rotatable holder 110 and a cutting tool 120 attached to a tool post that is movable in three dimensions. For example, an NC lathe is used.

  A workpiece 130 that is a base material of the rotor hub 70 is fixed to a holder 110 having a collet chuck, a three-jaw chuck, and the like. At this time, the center axis of the workpiece 140 is determined in advance, and the rotation center axis of the holder 110 is adjusted to be the same. Next, the holder 110 is rotated, and the outer peripheral surface 71, the disk mounting surface 72, and the hole 74 of the rotor hub 70 are cut by applying a tool 120 that can move in three dimensions to the work 130. Thereby, the outer peripheral surface 71, the disk mounting surface 72, and the hole 74 can be cut while being fixed to the holder 110. Therefore, when the workpiece 130 is removed from the holder 110 and fixed to the holder 110 again, the center of rotation is displaced. However, since the workpiece 130 remains fixed to the holder 110, the processing accuracy is high, particularly the coaxiality. Improved cutting can be realized.

  Further, when the shaft 30 having the same shape as the hole 74 formed in the rotor hub 70 is formed, the shaft 30 is austenitic stainless steel or martensitic stainless steel in consideration of slidability with the bearing sleeve 20 and wear resistance. It is necessary to use a highly rigid member such as steel. If it is going to process in order to form a hole in the highly rigid member, the cutting time at the time of a process will take, Furthermore, a general-purpose tool cannot be used for the cutting tool 120, and it is necessary to use a dedicated tool. In addition, there is a problem that the tool life is shortened. In comparison, since the rotor hub 70 uses a member having low hardness such as aluminum or free-cutting stainless steel, a general-purpose tool can be used for the cutting tool 120, and since the hardness is low, it does not take a cutting time and is further necessary. The tool life is not reduced as described above.

<5. Mounting method of recording disk>
FIG. 5 is a view showing an apparatus and a method for placing the recording disk 150 on the spindle motor according to the present invention. 5A is a schematic diagram of a disk mounting jig 140 described later, and FIG. 5B is a diagram illustrating a process of mounting the recording disk 150.

  The disc mounting jig 140 has a substantially cylindrical shape, and is a jig that can move in the axial direction with respect to a predetermined central axis. The center of the lower surface of the cylinder is fitted into the hole 74 of the rotor hub 70, the rotation center axis of the rotor hub 70 is aligned with the center of the lower surface of the cylinder, and is further movable in the axial direction at this center point. An axial protrusion 141 is formed. Further, a plurality of arc-shaped protrusions 142 are formed on the lower surface of the column at equal intervals in the circumferential direction around the axial protrusion 141 in the radial direction. The arc center of the arc-shaped protrusion 142 is the same as the center of the lower surface of the cylinder, the outer peripheral surface of the plurality of arc-shaped protrusions 142 arranged in the circumferential direction is the same as the recording disk 150, and the outer peripheral surface 71 of the rotor hub 70 It is almost the same. Further, a plurality of through holes 143 are arranged at equal intervals in the circumferential direction on the lower surface of the circular cylinder on the outer side in the radial direction of the arc-shaped protrusion 142. By sucking air upward from the through holes 143, the function of the vacuum chuck is achieved. Plays.

  Next, a process for mounting the recording disk 150 will be described.

  First, the central through hole of the recording disk 150 is disposed so as to be fitted to the outer peripheral surface of the arc-shaped protrusion 142 of the disk mounting jig 140. At that time, the recording disk 150 contacts and is fixed to the lower surface of the cylinder by the suction force from the through hole 143. Further, the center of the arcuate protrusion 142 coincides with the center of the through hole of the recording disk 150. The center of the arc-shaped protrusion 142 and the center of the cylinder lower surface are the same, and as a result, the axial protrusion 141 protruding from the center of the cylinder lower surface can coincide with the center of the through hole of the recording disk 150 ( Step S1).

  Next, the disk mounting jig 140 is moved downward in the axial direction so that the central axis of the hole 74 of the rotor hub 70 and the central axis of the protruding portion 141 are aligned (step S2). Thereby, the center of the through hole which is the rotation center of the recording disk 150 and the rotation center of the rotor hub 70 can be matched.

  Next, with the axial protrusion 141 fixed, the disk mounting jig 140 is moved downward in the axial direction to bring the lower surface of the arc-shaped protrusion 142 into contact with the upper end surface of the rotor hub 70 (step) S3). As a result, the outer peripheral surface of the arcuate protrusion 142 and the outer peripheral surface 71 of the rotor hub 70 are substantially connected, and a moving path of the recording disk 150 can be formed.

  Finally, the suction force of the through hole 143 of the vacuum chuck is weakened, the recording disk 150 is moved downward in the axial direction, and placed on the disk mounting surface 72 of the rotor hub 70 (step S4). Accordingly, since the recording disk 150 has a suction force so as to have a holding force on the upper side in the axial direction, by weakening this suction force, the recording disk 150 can be moved along the axial direction without causing the coaxiality to shift. It can be arranged on the disk mounting surface 72.

  As described above, the embodiment of the present invention has been described. However, the present invention is not limited to this embodiment, and various modifications can be made.

  For example, in the embodiment of the present invention, a so-called shaft rotation method in which the shaft 60 rotates is not limited to this rotation method, but a shaft fixing method may be used. Further, for example, in the embodiment of the present invention, the rotor magnet 90 is arranged around the outer side in the radial direction of the stator 80 so as to rotate. However, the radius of the stator 80 is not limited thereto. A so-called inner rotor system in which the rotor magnet 90 is arranged around the inner side in the direction of rotation may be used.

  For example, in the embodiment of the present invention, the axial protrusion 141 of the disk mounting jig 140 has a substantially cylindrical shape, and the hole 74 of the rotor hub 70 has a cylindrical through hole. The shape of the axial direction protrusion part 141 and the hole 74 may correspond, and what is necessary is just a shape which mutually matches a center axis | shaft. For example, the axial protrusion 141 may have a conical shape, and the hole 74 may fill the conical shape. Moreover, the hole 74 is not limited to a through-hole like FIG. 2 and FIG. However, in order to improve the coaxial accuracy between the shaft 30 and the hole 74, a through hole is desirable.

  Further, for example, in the embodiment of the present invention, the hole 74 and the fitting hole 75 of the rotor hub 70 are formed. However, the present invention is not limited to this, and only the fitting hole 75 may be used as shown in FIG. FIG. 6 is a view showing another embodiment in which the dotted line portion is enlarged similarly to FIG.

  However, in order to perform center axis alignment with the axial protrusion 141 of the disk mounting jig 140, the end surface of the shaft 30 and the upper end surface of the rotor hub 70 are axial in the fixing of the shaft 30 and the fitting hole 75. The circular concave portion 77 is formed by disposing the end face of the shaft 30 slightly below without matching with the above. The recording disk 150 may be disposed by matching the central axis of the circular recess 77 with the central axis of the axial protrusion 141.

1 is a schematic axial sectional view showing an embodiment of a recording disk drive device according to the present invention. It is the axial direction schematic cross section which showed one form of the Example of the spindle motor based on this invention. FIG. 3 is an enlarged view of FIG. 2 illustrating a fitting portion between a shaft and a rotor hub according to the present invention. It is a schematic cross section of the processing apparatus of the rotor hub according to the present invention. a) is a schematic diagram of a disk mounting jig according to the present invention, and b) is a diagram showing a process of mounting a recording disk on a rotor hub. It is the figure which showed the other Example which showed the fitting part of the shaft and rotor hub which concern on this invention. It is an axial schematic cross section showing a spindle motor according to a conventional example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Recording disk drive apparatus 10 Base 20 Bearing sleeve 30 Shaft 40 Thrust plate 50 Plate 60 Stator 70 Rotor hub 71 Outer peripheral surface 72 Disc mounting surface 73 Cylindrical part 74 Hole 75 Fitting hole 76 Step part 77 Circular recessed part 80 Rotor yoke 90 Rotor magnet 100 Processing device 110 Holder 120 Bit 130 Work 140 Disc placement jig 141 Axial projection 142 Arc-like projection 143 Through hole 150 Recording disc

Claims (5)

A substantially cylindrical shaft disposed coaxially with the rotation center axis;
A rotor hub that covers an upper end surface of the shaft body and is substantially coaxial with the rotation center axis;
A rotating body with
A fixing member that rotatably supports the rotating body via bearing means;
In a spindle motor composed of
The rotor hub is
A cylindrical outer peripheral surface formed concentrically with the rotation center axis and into which a central hole of a disc-shaped recording disk is fitted;
A disk mounting surface formed on a plane substantially orthogonal to the rotation center axis, on which the recording disk is mounted;
An axial fitting hole formed concentrically with the rotation center axis and having a cylindrical inner peripheral surface to which the shaft body is fixed;
The shaft body is fitted and fixed to the fitting hole leaving the upper portion of the fitting hole, so that the fitting hole and the end surface of the shaft body are concentric with the rotation center of the rotor hub. A spindle motor characterized in that a circular concave portion opened in is formed.   2. The spindle motor according to claim 1, wherein a hole having a diameter smaller than a diameter of the shaft body in a radial direction is provided in a part of the upper side of the fitting hole. A recording disk having a magnetic recording layer;
A magnetic head for recording information on the magnetic recording layer and reproducing the information recorded on the magnetic recording layer;
Moving means for moving the magnetic head relative to the recording disk;
A spindle motor according to any one of claims 1 and 2, for rotating the magnetic disk.
A recording disk drive device comprising: A method of placing a recording disk using a disk placement jig on a spindle motor equipped with a rotor hub arranged coaxially with a rotation center axis,
The rotor hub is
A cylindrical outer peripheral surface formed concentrically with the rotation center axis and into which a central hole of a disc-shaped recording disk is fitted;
A disk mounting surface formed on a plane substantially orthogonal to the rotation center axis, on which the recording disk is mounted;
An axial fitting hole formed concentrically with the rotation center axis and having a cylindrical inner peripheral surface to which the shaft body is fixed;
A shaft body that serves as a rotation shaft of the spindle motor is fitted into the fitting hole, leaving a top portion of the fitting hole, and is formed into a circular recess.
While using the fitting hole formed in the rotor hub for positioning the disk mounting jig,
The disk mounting jig includes a positioning protrusion at the center of the recording disk that fits with the circular recess of the rotor hub,
A step of positioning the recording disk with respect to the disk mounting jig;
Fitting the positioning protrusion into the circular recess of the rotor hub;
Placing the recording disk on the rotor hub;
A method of manufacturing a recording disk drive device comprising: A mounting surface substantially orthogonal to the rotation center axis on which the recording disk is mounted;
While determining the central axis that is a specific axis for a given member,
A cylindrical outer peripheral surface around the central axis;
A hole having a cylindrical inner peripheral surface centered on the central axis;
A method for processing a rotor hub of a spindle motor comprising:
For processing, using at least one each of a rotatable holder for holding the base material before processing of the rotor hub and a cutting tool for cutting the base material,
Holding the base material so that the central axis of rotation of the holder and the central axis are substantially coaxial;
Cutting the outer peripheral surface and the hole in a state where the holder is held by one holder while rotating the holder with respect to the tool;
The manufacturing method of the rotor hub of a spindle motor characterized by including these.

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