JP2001067755A - Chucking device for magnetic disk - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce wobbling of the chucking face of a chucking magnet by bonding the inner circumference of the opposite face of a chucking face to the surface of a rotor by an adhesive layer and forming a gap between the inner circumference and the rotor surface, in a chucking magnet having a chucking face for attracting the hub of a magnetic disk. SOLUTION: The axial hole 5a of a bearing 5 on a base plate 1, a stator member of a spindle motor, axially supports freely rotatably a rotary shaft 6 on which a rotor 4 is fixed. An adhesive layer 9 made of a UV adhesive is formed at a prescribed thickness on the entire surface of the third step 4d of the rotor 4, while a chucking magnet 10 made of a disk-like magnet is attached to the adhesive layer 9. The chucking magnet 10 is fixed on the rotor 4 through the adhesive layer 9, with the chucking face 10a positioned vertically against the axial direction of the rotary shaft 6. As a result, wobblng is reduced on the chucking face 10a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic disk chucking device for chucking and rotating a magnetic disk such as a floppy (registered trademark) disk.

[0002]

2. Description of the Related Art In a magnetic disk chucking device of this type, a plurality of drive coils 2 are arranged on the same circumference on a substrate 1 as shown in FIG. A ring-shaped rotor magnet 3 is provided at a position facing the drive coil 2.
Are attached inside the side wall 20 a on the outer peripheral side of the rotor 20. The rotor 20 has a flat surface 20b whose central part protrudes upward.
The boss hole 20c is formed by burring or the like. The boss hole 20c is press-fitted into the rotating shaft 6, and the rotor 20 is fixed to the rotating shaft 6, and is rotatably supported by the bearing 5 on the substrate 1.

If the flat surface 20b of the rotor 20 press-fitted and fixed to the rotary shaft 6 is perpendicular to the axis of the rotary shaft 6, the flat surface 20b of the rotary shaft 6 is rotated when the rotor 20 is rotated. The runout of the flat surface 20b is reduced in the axial direction, and a high performance magnetic disk chucking device can be provided. However, actually, the boss hole 2 of the rotor 20 is used.
0c, and variations in the press-fitting strength between the rotating shaft 6 and the rotor 20 due to variations in the burring process.
It was difficult to press-fit vertically and attach to the direction of the axis. Therefore, the flat surface 20b of the rotor 20
We used the surface run-out after sorting out 100%.

A rotary shaft 6 supported by the bearing 5
At one end, a shaft stopper 7 is attached to the opening 1a of the substrate 1, so that the rotating shaft 6 does not come out to the substrate 1 side. Further, the bearing 5 has a stopper 8 integrated with the drive coil 3 fixed to the substrate 1 by screwing.

An adhesive (not shown) is partially thinly applied to a plurality of portions on the flat surface 20b of the rotor 20, and a chucking magnet 10 composed of a disk-shaped magnet is mounted thereon. And the flat surface 20b of the rotor 20
Installed on top. The chucking magnet 10 has an opening 10a at the center thereof and a flat chucking surface 10b protruding around the opening 10a. And the adhesive (not shown)
Since a low-viscosity material such as water is thinly and partially applied on the flat surface 20b, the chucking when the chucking magnet 10 is mounted and fixed on the adhesive is applied. The runout of the surface 10b is
Of the flat surface 20b.

For this purpose, the flat surface 20 of the rotor 20
If b is not mounted perpendicular to the axis of the rotating shaft 6 and the flat surface 20b has a large surface runout, the chucking surface 10b has a large surface runout.
In addition, some chucking magnets 10 vary in the degree of parallelism between the chucking surface 10b and the bonding surface 10c bonded to the bonding layer 9 due to manufacturing variations and the like. For this reason, there was an object in which the runout of the chucking surface 10b was further increased.

In addition, the chucking magnet 10
A drive pin 11 is attached to a drive pin attachment hole 20f of the rotor 20 on the outer peripheral side of the rotor 20.
The upper surface thereof is mounted so as to protrude from the chucking surface 10b of the chucking planet 10 to constitute a conventional magnetic disk chucking device.

In order to assemble a conventional chucking apparatus for a magnetic disk having such a structure, one end of a rotating shaft 6 is held on a rotating shaft holder of a jig (not shown), and a rotor magnet is attached to the other end of the rotating shaft 6. Boss hole 2 of rotor 20 with 3 attached
0c, the flat surface 20b of the rotor 20 is pressed by the upper mold of the jig, and the flat surface 20b is positioned perpendicularly to the axial direction of the rotary shaft 6, so that the predetermined Press into the position.

Next, the rotor 20 press-fitted into the rotating shaft 6 is
Is to select all the runouts of the flat surface 20b in the axial direction when the rotor 20 is rotated by a predetermined jig (not shown), and if the runout is larger than a predetermined value, the description is omitted. However, the run-out was corrected using a correction jig.

Next, the driving pin 1 is inserted into the driving pin mounting hole 20f of the flat surface 20b of the rotor 20 into which the rotating shaft 6 is press-fitted.
1 is applied, and an adhesive (not shown) is partially thinly applied to a plurality of locations on the flat surface 20b of the rotor 20, and the chucking magnet 10 is placed on the thinly applied adhesive. Is mounted on the flat surface 20b of the rotor 20, and the rotor 20 is unitized. Then, one end of the rotating shaft 6 of the unitized rotor 20 is inserted into the bearing 5 attached to the substrate 1, and the assembly of the conventional magnetic disk chucking device is completed.

On the other hand, a commercially available disk cartridge (not shown in its entirety) loaded in the above-described chucking device stores a flexible disk 12 as a magnetic recording medium, and A hub 13 is attached to the disk 12.
An opening 13a is provided at the center of rotation of the hub 13,
A rectangular positioning hole 1 is provided near the outer periphery of the hub 13.
3b are formed, and the magnetic disk has a well-known configuration.

In the conventional magnetic disk chucking device having the above-described configuration, the hub 13 to which the flexible disk 12 is attached is attracted to the chucking surface 10b by the magnetic force of the chucking magnet 10, and the driving pin 11 is engaged with the positioning hole 13 b of the hub 13, and the magnetic disk is rotated by the rotation of the rotor 20 to which the rotating shaft 6 is attached, so that the magnetic head (not shown) contacts the surface of the flexible disk 12. In this way, data is recorded and reproduced. Therefore, if the flexible disk 12 is rotating and the surface deflection of the flexible disk 12 in the axial direction is large, the contact with the magnetic head becomes unstable and accurate recording and
There was a problem that playback could not be performed.

Therefore, the hub 13 of the magnetic disk
Of the chucking surface 10b of the chucking magnet 10 that absorbs
The chucking surface 10 during one rotation of the magnet 10
On the outer peripheral side of b, the backlash of the bearing 5 and the rotating shaft 6 is included.
Strict control was required to be within the range of 02 mm.

[0014]

However, in the conventional magnetic disk chucking device described above, the rotor 20 is press-fitted into the rotating shaft 6 and the press-fitted rotor 2 is pressed.
Since the chucking magnet 10 is mounted on the basis of the flat surface 20b of zero, the runout of the chucking surface 10b of the chucking magnet 10 depends on the runout of the rotor 20, and In order to suppress the runout, it was necessary to reduce the runout of the flat surface 20b. However, variations in the verticality of the boss holes 20c due to variations in the processing of the rotor 20,
The flat surface 20b does not become perpendicular to the axial direction of the rotating shaft 6 due to variations in the press-fit strength of the rotor 20 and the like.
In some cases, the runout of 0b became large. for that reason,
Since all the runouts of the flat surface 20b were selected and those having a runout of a predetermined value or more were selected, the assembly work efficiency was poor.

Further, the adhesive is applied to the flat surface 20b of the rotor 20, and the chucking magnet 10 is placed and mounted on the flat surface 20b. However, the adhesive hardens and the chucking magnet 10 is attached to the flat surface 20b. It took time to fix 10. As a result, it takes time to assemble the chucking device, and the assembling efficiency is poor.

The chucking magnet 10 is
The chucking surface 10b may vary due to manufacturing variations.
And the parallelism between the bonding surface 10c bonded to the bonding layer 9 and the flat surface 20b of the rotor 20 was varied. There was an object in which the chucking surface 10b of the chucking magnet 10 had large runout.

In order to reduce the runout of the flat surface 20b of the rotor 20, the precision of the perpendicularity of the boss hole 20c to the flat surface 20b is improved.
There is a problem that the mold structure becomes highly accurate and the mold becomes expensive.

[0018]

As a first means for solving the above-mentioned problems, a rotating shaft to which a rotor is fixed, a magnetic disk comprising a flexible disk and a hub, and a chuck for attracting the hub of the magnetic disk are provided. A chucking magnet having a king surface, and an adhesive layer formed on the surface of the rotor, wherein the chucking magnet has an inner peripheral portion opposite to the chucking surface and has an inner peripheral portion bonded to the surface of the rotor. The rotor is adhered and attached by a layer, and a gap is formed between the outer peripheral portion of the opposite surface and the surface of the rotor.

In the first means, the adhesive layer is made of a UV adhesive, and the chucking surface is perpendicular to the axis of the rotation axis via the adhesive layer. The chucking magnet was attached to the surface of the rotor.

As a second means for solving the above-mentioned problem, as a reference, the chucking surface of the chucking magnet is perpendicular to the axis center direction with respect to the axis direction of the rotating shaft to which the rotor is fixed. The chucking magnet is attached to the rotor, and the runout of the chucking surface of the chucking magnet is set to be smaller than the runout of the surface of the rotor to which the chucking magnet is attached. The configuration was adopted.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a magnetic disk chucking device according to the present invention will be described below with reference to FIGS. The same parts as those described in the related art will be described with the same reference numerals.

In the magnetic disk chucking apparatus of the present invention, for example, as shown in FIG. 1, a plurality of drive coils 2 are arranged on the same circumference on a substrate 1 which is a stator member of a spindle motor. At a position on the outer peripheral side facing the drive coil 2, a ring-shaped rotor magnet 3 is formed by gluing a metal plate made of iron or the like into an outer peripheral side wall 4 a of a rotor 4 formed into a cylindrical shape by drawing or the like. It is attached in close contact with etc. The rotor 4 has a stepped first stepped portion 4b, a second stepped portion 4c, and a third stepped portion 4d, each of which has a stepped shape from the outer peripheral side and has a ring shape. The third step near the center is the highest. A boss hole 4e projecting inward by burring or the like is formed in the center of the rotor 4, and a drive pin mounting hole 4f is formed in the second step portion 4c.

Further, on the substrate 1, a rotary shaft 6 made of metal or the like is rotatably supported in a shaft hole 5a of a bearing 5 made of a copper alloy such as brass so as to be free of shaft play. The boss hole 4e of the rotor 4 is press-fitted into the rotating shaft 6, and the rotor 4 is moved in the axial direction of the rotating shaft 6 (the direction of arrow A).
Is fixed at a predetermined position.

A rotary shaft 6 supported by the bearing 5
At one end of the substrate, a plate-shaped shaft stopper 7 has an opening 1a of the substrate 1.
The plate-shaped shaft stopper 7 attached to the shaft abuts, and the rotating shaft 6 is mounted on the bearing 5. Also, the bearing 5
It is fixed to the substrate 1 by a metal fitting 8 by screwing. Since the metal fitting 8 and the plurality of driving coils 2 are integrated, when the metal fitting 8 is screwed to the substrate 1, the driving coil 2 is also fixed to the substrate 1 at the same time.

An adhesive layer 9 made of a UV adhesive is formed with a predetermined thickness on the entire surface of the third step portion 4d projecting in a ring shape near the center of the rotor 4.
The chucking magnet 10 made of a disk-shaped magnet is placed on the surface of the rotor 4, and the chucking magnet 10 is attached to the third step of the rotor 4. The chucking magnet 10 has the rotating shaft 6 at its center.
And an opening 10a forming a gap, and a ring-shaped, flat chucking surface 10b is provided near the opening 10a.
Are formed to protrude.

When the chucking magnet 10 is positioned perpendicular to the axis of the rotary shaft 6 supported by the bearing 5,
It is attached to the rotor 4 via the adhesive layer 9. For this reason, the runout of the chucking surface 10b is reduced, and it is not necessary to select all runouts as described in the above-described conventional technique.

The chucking magnet 10
The drive pin 11 is provided on the outer peripheral side of the
The upper surface of the drive pin 11 is mounted so as to protrude from the chucking surface 10 b of the chucking magnet 10, and the upper surface of the drive pin 11 is attached to the chucking magnet 10. And can move up and down to the same plane as the chucking surface 10b.

On the other hand, a flexible disk 12 as a magnetic recording medium is provided in a central portion of a disk cartridge (not shown in its entirety), which is a commercially available product, which is loaded into the above-described chucking device. It is attached to the hub 13 and housed. And the hub 1
Reference numeral 3 denotes a chucking surface 10 by the magnetic force of the chucking magnet 10 when loaded in the chucking device of the present invention.
b is formed of a magnetic material such as iron so as to be adsorbed to the opening 1b, and the center of rotation thereof has an opening 1 into which the rotating shaft 6 can be fitted.
3a is provided in a quadrangular shape.

In the vicinity of the outer periphery of the hub 13, a rectangular positioning hole 13b for inserting the drive pin 11 to rotate the flexible disk 12 is formed, and the magnetic disk is formed in a well-known configuration. ing.

In the magnetic disk chucking device having the above configuration, when power is supplied to the drive coil 2 in a predetermined phase, the rotor 4 having the chucking magnet 10 attached with the adhesive layer 9 rotates. Then, the drive pin 11 rotates following the rotation, the hub 13 with which the drive pin 11 is engaged rotates, and the flexible disk 12 also rotates.

Such a magnetic disk chucking device rotates a magnetic disk composed of a flexible disk 12 and a hub 13 to bring a magnetic head (not shown) into contact with the surface of the flexible disk 12.
Flexible recording and playback of data. The surface deflection of the disk 12 must be small.

Therefore, in the magnetic disk chucking apparatus of the present invention, the flexible disk 12
The chucking surface 10b for sucking and holding the
The vertical run of the chucking surface 10b is small even if the vertical run of the third step portion 4d of the rotor 4 is large. For this reason, the runout of the flexible disk 12 attached to the hub 13 attracted to the chucking surface 10b is reduced, and the contact between the flexible disk 12 and the magnetic head is stabilized, and high-precision recording / recording is performed. Playback can be performed.

A method of manufacturing a magnetic disk chucking device having such a configuration will be described. As shown in FIG. 2, a first step of the manufacturing method is as follows.
The assembly jig (the whole is not shown) is inserted into a shaft hole 15a formed in the rotary shaft holder 15 which is the first jig. At this time, the rotation shaft 6 has a shaft surface 15a.
And is held by the rotation holding base 15 in a state of being immersed in the shaft hole 15a by a predetermined depth Y in the shaft hole 15a.

The upper die 1 is arranged such that the boss hole 4e of the rotor 4 is aligned with the other end of the rotating shaft 6 and the surface 15b of the rotating shaft holding base 15 is opposed to the upper side.
6 is lowered in the axial direction (the direction of arrow B) by a small press or the like, and the third step portion 4d of the rotor 4 is formed by a flat pressing surface 16b which is installed perpendicularly to the axial direction of the rotating shaft 6. When the is pressed, the inner surface of the third step portion 4d of the rotor 4 comes into contact with the surface 15b of the rotary shaft holding base 15, and the other end of the rotary shaft 6 projects into the opening 16a of the upper die 16, The press-fitting operation of the rotor 4 into the rotating shaft 6, that is, the first step is completed.

Next, in the second step of the manufacturing method, the second flat surface of the rotor 4 in a state where the upper die 16 is moved upward from the state shown in FIG. 4c
The drive pin 11 is inserted into and attached to the drive pin mounting hole 4f, a liquid primer is applied to the surface of the third step portion 4d of the rotor 4, and an adhesive layer 9 made of a UV adhesive is further applied thereon. It is applied with a predetermined thickness, and a chucking magnet 10 is placed on the surface of the adhesive layer 9.

As shown in FIG. 3, the upper die 16 of the assembling jig is lowered again, and the pressing surface is set perpendicular to the axial center direction of the rotary shaft 6 with respect to the axial center direction. 1
When the chucking surface 10b is pressed at 6b, the adhesive surface 10c of the chucking magnet 10 compresses the uncured adhesive layer 9 made of the UV adhesive, thereby causing variations in the attachment of the rotor 4 to the rotating shaft 6 (rotation). Irrespective of the degree of perpendicularity between the shaft 6 and the third step portion 4d) and the degree of parallelism between the chucking surface 10b and the bonding surface 10c, the upper die 16 does not matter.
The chucking surface 10b follows the pressing surface 16b
Is positioned perpendicular to the axial direction of the rotating shaft 6 and is temporarily fixed to the rotor 4 so that the dimension from one end of the rotating shaft 6 to the chucking surface 10b becomes a predetermined dimension Z. 1
The pressing of 6 stops.

At this time, the adhesive layer 9 is sandwiched and pressed between the rotor 4 and the chucking magnet 10, so that the adhesive layer 9 protrudes from the outer peripheral side of the third step portion 4d and both sides on the rotating shaft 6 side. Has become.

Then, as shown in FIG. 3, the chucking surface 1 is held between the rotating shaft holder 15 and the upper die 16 of the assembly jig.
0b is sandwiched in a sandwich shape so as to be perpendicular to the axis direction of the rotating shaft 6 with respect to the axis direction of the rotating shaft 6, and the chucking magnet 10 is pressed against the adhesive layer 9; When irradiated with ultraviolet rays, the adhesive layer 9 made of a UV adhesive is cured in a short time, and the chucking surface 1 is hardened.
The chucking magnet 10 is fixed to the third step portion 4d of the rotor 4 and is unitized.

Since the primer is interposed between the third step portion 4d and the adhesive 9, when the rotor 4 is machined into a cylindrical shape, the processing oil sprayed on the rotor 4 or the assembly oil It is possible to remove the bathing of the worker's hand and the like adhering to the row 4 during operation, promote the effect of the adhesive layer 9, and strengthen the bond between the third step portion 4d and the adhesive layer 9. Can be.

Next, as a third step, as shown in FIG. 1, a cover 7 is placed over the opening 1a at the center of the substrate 1 with a stopper 7, and the bearing 5 is placed thereon. Next, a metal fitting 8 in which a plurality of drive coils 2 are integrated is put on the bearing 5 and screwed.
, The bearing 5 and the stopper 7 are attached to make a unit.

Next, as a fourth step, the rotor magnet 3, the rotor 4, the rotating shaft 6, and the chucking magnet 10 are placed in the shaft hole 5a of the bearing 5 of the substrate 1 unitized in the third step. When one end of the rotating shaft 6 of the rotor 4 attached and unitized is inserted, one end of the rotating shaft 6 comes into contact with the shaft stopper 7, and the unitized rotor 4 is supported by the bearing 5.

At this time, the unitized rotor 4
Does not fall out of the bearing 5 even if the rotor magnet 3 and the drive coil 2 attract and the external vibration or the like is applied. Further, the unitized rotor 4 includes the substrate 1,
A predetermined gap is formed between the drive coil 2 and the bearing 5, and the gap is rotatably supported by the shaft hole 5 a of the bearing 5, thereby assembling the magnetic disk chucking device of the present invention. finish.

Further, since the chucking surface 10b of the chucking magnet 10 is mounted so as to be perpendicular to the axis of the rotating shaft 6, the chucking surface 10b of the chucking surface 10b is not affected even when the rotor 4 rotates. Since the runout is in a small range that does not affect the recording / reproduction on the magnetic disk, it is not necessary to inspect the runout of the chucking surface 10b completely after the assembly of the magnetic disk chucking device of the present invention. Good.

In such an embodiment of the present invention, the fixing of the rotor 4 and the rotating shaft 6 is not limited to press-fitting. In another embodiment, for example, as shown in FIG. A configuration may be adopted in which a gap is provided in the boss hole 4 e of the rotor 4. In the method of manufacturing the chucking device having such a configuration, one end of the rotating shaft 6 is held in the shaft hole 15 a of the rotating shaft holding base 15, and the boss hole 4 e of the rotor 4 is connected to the other end of the rotating shaft 6. When the rotor 4 is inserted, the inner surface of the third step portion 4d of the rotor 4 is placed on the surface 15b of the rotating shaft holding base 15, and the rotor 4 is moved from the predetermined position of the rotating shaft 6, that is, one end of the rotating shaft 6 by a dimension Y. By the way, it is positioned.

At this time, the second stepped portion 4c of the rotor 4 and the third
The step at the boundary of the step 4d is moved to the rotating shaft holder 15 of the assembly jig.
Is positioned so that the center of the rotor 4 and the center of the rotating shaft 6 are concentric.

Next, an adhesive layer 9 made of a UV adhesive is applied to a predetermined thickness on the third flat surface 4 d of the rotor 4, and the adhesive layer 9 is formed in contact with the outer peripheral surface 6 a of the rotating shaft 6. Then, the chucking marnet 10 is positioned and placed on the adhesive layer 9. Subsequent assembling is the same as in the above-described embodiment of the present invention, and a description thereof will be omitted.

In such another embodiment, the rotating shaft 6, the rotor 4, and the chucking magnet 10 can be fixed by the adhesive layer 9 made of a UV adhesive. As described in the embodiment, the operation of press-fitting the rotor 4 into the rotating shaft 6 in the first step of the manufacturing method becomes unnecessary, and the assembling operation is simplified, so that a low-cost chucking device can be provided.

The irradiation of the adhesive layer 9 with ultraviolet rays was performed in a state where the chucking magnet 10 was pressed against the adhesive layer 9. However, the irradiation was performed after the chucking magnet 10 was pressed against the adhesive layer 9. Is also good.

[0049]

According to the chucking device of the present invention, there is provided a rotating shaft to which a rotor is fixed, a magnetic disk comprising a flexible disk and a hub, a chucking magnet having a chucking surface for attracting the hub of the magnetic disk, An adhesive layer formed on the surface of the rotor, wherein the chucking magnet has an inner peripheral portion opposite to the chucking surface adhered and attached to the surface of the rotor by the adhesive layer, A gap is formed between the outer peripheral portion of the opposite surface and the surface of the rotor, and the chucking surface of the chucking magnet is formed on the basis of the axial direction of the rotating shaft to which the rotor is fixed. The chuck is manufactured by attaching the chucking magnet to the rotor so as to be perpendicular to the axial direction. A small surface runout of grayed surface, the contact between the magnetic head and the floppy disk is stabilized, it is possible to provide a chucking device for a magnetic disk that can accurate recording and playback.

Also, since the chucking surface is perpendicular to the axis of the rotating shaft via an adhesive layer made of a UV adhesive, and a chucking magnet is attached to the surface of the rotor, The curing time of the agent can be shortened, and the assembling time of the magnetic disk chucking device can be shortened. In addition, the adhesive layer absorbs variations in the attachment of the rotor to the rotating shaft (runout) and variations in the parallelism between the chucking surface of the chucking magnet and the adhesive surface. Since it can be mounted perpendicularly to the axis direction, the runout of the chucking surface is reduced, the inspection of all the runouts becomes unnecessary, and the cost of the chucking device for the magnetic disk can be reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view of an essential part of a magnetic disk chucking device according to the present invention.

FIG. 2 is a sectional view of an essential part for explaining the assembly of the magnetic disk chucking device of the present invention.

FIG. 3 is a sectional view of an essential part for explaining the assembly of the magnetic disk chucking device of the present invention.

FIG. 4 is a sectional view of an essential part for explaining another embodiment of the present invention.

FIG. 5 is a sectional view of a main part of a conventional magnetic disk chucking device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Drive coil 3 Rotor magnet 4 Rotor 6 Rotating shaft 7 Axis fixing 9 Adhesive 10 Chucking magnet 11 Drive pin 12 Flexible disk 13 Hub 15 Rotation axis holding stand 20 Rotor

Claims (3)

[Claims] 1. A rotating shaft to which a rotor is fixed, a magnetic disk comprising a flexible disk and a hub, a chucking magnet having a chucking surface for attracting the hub of the magnetic disk, and a surface formed on the surface of the rotor. The chucking magnet, the inner peripheral portion opposite to the chucking surface is attached to the surface of the rotor by bonding with the adhesive layer,
A magnetic disk chucking device, wherein a gap is formed between an outer peripheral portion of the opposite surface and a surface of the rotor. 2. The method according to claim 1, wherein the adhesive layer is made of a UV adhesive, and the chucking surface is perpendicular to an axis of the rotating shaft via the adhesive layer. The chucking device for a magnetic disk according to claim 1, wherein a magnet is mounted. 3. The chucking magnet is attached to the rotor such that the chucking surface of the chucking magnet is perpendicular to the axial center direction with respect to the axial direction of the rotating shaft to which the rotor is fixed. The chucking device for a magnetic disk, wherein a runout of a chucking surface of the chucking magnet is set smaller than a runout of a surface of the rotor to which the chucking magnet is mounted. .