JPH10241273A - Spindle motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotor case superior in economy by press work of a magnetic plate. SOLUTION: The rotor case 18 is produced by press work on an iron plate and a silicon steel plate, etc., to integrally form a boss part 22 for inserting and fixing a shaft 20 into a central hole 24, an annular recessed part 32 to be engaged with a chucking magnet 34, an annular mold fixing part 42 and an outer circumferential cylinder part 30. This rotor case 18 itself functions as a magnetic shield. A disk placing part 40 and an upper bottom surface 50 are formed of synthetic resins by outsertion molding through a through hole 44 of the annular mold fixing part 42. An open end periphery 26 of the boss part 22 is brought into press-contact with an inner race 28 of a ball bearing, and a driving magnet 52 is abutted with its upper end surface 60 against the upper bottom surface 50 to settle its relative position in the axial direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disk drive for rotating a magneto-optical disk or various magnetic media equivalent thereto, and more particularly, to an improvement in a rotor case of a spindle motor for mounting a disk. About.

[0002]

2. Description of the Related Art As shown in FIG. 2, a spindle motor 100 for driving a disk is generally provided with a base frame 1.
The bearing 10 has a bearing portion 111 and a flat portion 112, and a pair of ball bearings 113 is fitted in the bearing portion 111 to rotatably support a shaft 114. Bearing part 111
A laminated core 115 is fitted around the outer periphery of the laminated core 1.
A drive coil 116 is wound around 15.

A rotor 118 made of a non-magnetic material such as aluminum for mounting a disk 117 is fixed to the shaft 114, and an annular chucking magnet 119 is provided on the surface on which the disk 117 is mounted.
It is buried via a magnetic yoke 120.

The disk 117 is held by a magnetic attraction plate 121. When a through hole 122 at the center of the attraction plate 121 is inserted into the head of the shaft 114 and placed on the rotor 118, the attraction plate 121 is moved to the chucking magnet. The lower surface of the disk 117 abuts on the top surface 124 of the peripheral wall 123 of the rotor 118 by being sucked by the disk 119, and the disk 117 is fixed to the top surface 124 of the rotor 118 by magnetic force. A cushioning anti-slip plate 124a is attached to the top surface 124 as an effective contact holding means for the disk 117.

[0005] The cylindrical yoke 12 is provided around the rotor 118.
5 is integrally fixed by means such as press-fitting, and the drive magnet 12 is arranged so as to face the inner peripheral surface of the cylindrical yoke 125 at a predetermined distance from the outer peripheral surface 126 of the laminated core 115.
7 is fixed.

A frequency generator 128 is formed, and one of the components, a frequency power magnetizing 129, is provided.
Is applied to the lower end surface of the cylindrical yoke 125 and the other component, a frequency power generation pattern (FG pattern) 131
Are laid on a printed circuit board 130 fixed to the flat portion 112 of the base frame 110, and are opposed to each other with a predetermined close distance therebetween. Furthermore, printed circuit board 1
A position detecting magnetic sensor (Hall element) 132 is provided on the area 30 within a region where the magnetic flux of the drive magnet 127 works effectively.
Is installed.

When the disk 117 is placed on the rotor 118 and the drive coil 116 is energized, a rotational force is applied to the cylindrical yoke 125 by an electromagnetic interaction between the magnetic field of the current and the magnetic force of the drive magnet 127, and Numeral 118 rotates the mounted disk 117 about the shaft 114.

[0008]

Since the rotor 118 of the prior art described above is generally a molded product by casting, the top surface 124 of the peripheral wall 123 on which the disk 117 is mounted after casting.
In order to ensure the accuracy with respect to the flatness of the shaft and the perpendicularity with the shaft 114, cutting is required. In addition, the cutting of a metal material requires man-hours in terms of machinability as compared with a synthetic resin material, which greatly affects the production cost and is economically disadvantageous.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a spindle motor having a rotor case which is easy to process by pressing a magnetic plate and resin molding and which is excellent in economy.

[0010]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention comprises a shaft, a bearing for rotatably supporting the shaft, a disk chucking magnet and a disk mounting portion. A rotor case fixed and rotating integrally with the rotor case, wherein the rotor case is a molded product obtained by plastic deformation of a magnetic plate, and the chucking magnet is fixed to a bottom surface of the molded annular concave portion; The mounting portion is formed of a synthetic resin material, and a part of the mounting portion is integrally fixed to the rotor case in such a manner as to extend through the rotor case and form a surface on the side opposite to the disk mounting portion and extend. Was.

Further, a cylindrical portion is formed on the outer periphery of the rotor case, and the end surface of the driving magnet mounted on the inner surface of the cylindrical portion is extended by a synthetic resin formed on the side opposite to the disk mounting portion. Surface.

Further, at least one of the bearings is formed of a ball bearing, and the rotor case is fitted and fixed to the shaft by a boss formed integrally, and an open edge of the boss is formed on the inner race of the ball bearing. To be pressed against.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a rotor case of a spindle motor according to the present invention will be described below with reference to the drawings. FIG. 1 shows a spindle motor 10 according to the present invention.
The bearing holder 14 erected on the base frame 12 has a pair of ball bearings 1.
6 on which the rotor case 18 is fixedly mounted.
0 is rotatably supported.

The rotor case 18 is formed of a magnetic plate material such as an iron plate or a silicon steel plate by plastic deformation such as press molding, and has a central portion directed toward the inside of the spindle motor 10 (downward in the figure). A through hole 24 is formed by providing a cylindrical boss portion 22, and the shaft 20 is fixed to the through hole 24.

The rotor case 18 rotates integrally with the open end edge 26 of the boss portion 22 while being biased so as to press against the upper surface of the inner ring 28 of the upper ball bearing 16. Due to this pressing action, the inner ring 28 of the ball bearing 16,
Since the ball 16a and the outer ring 29 come into close contact with each other along the line of arrow F, and there is no play, the relative position of the rotor case 18 is determined in the axial direction.

Further, in the rotor case 18 formed by integral press molding of a magnetic plate material, an annular concave portion 32 is formed between the boss portion 22 and the outer peripheral cylindrical portion 30 together with the boss portion 22. The chucking magnet 34 is fixed. This chucking magnet 34
When the disk 35 is aligned and mounted on the rotor case 18, the magnetic attraction plate 35 a supporting the disk 35
Acts to fix by suction. Disk 35
By inserting the center through hole 35b of the magnetic attraction plate 35a into the top 20a of the shaft 20, it can be placed concentrically with the rotor case 18 and aligned.

Since the annular concave portion 32 of the magnetic plate functions as a magnetic shield surrounding the bottom surface 34a, the inner peripheral surface 34b, and the outer peripheral surface 34c of the chucking magnet 34 as shown in the figure, it is particularly necessary to provide a magnetic member. Is eliminated, and the device can be made thinner accordingly.

The outer edge 36 of the annular recess 32 and the outer cylindrical portion 30
An annular disk mounting portion 40 having a smooth upper surface is formed by integral molding using an outsert mold of a synthetic resin material. Further, a plurality of through holes 44 are formed in the rotor case 18 at equal intervals along the circumference of the annular mold fixing portion 42 that engages with the disk mounting portion 40. At the same time as the insert molding, through the through hole 44, on the lower surface side of the annular mold fixing portion 42,
Outer wall 46 of annular recess 32 and inner peripheral surface 48 of outer cylindrical portion 30
, A smooth upper bottom surface 50 is integrally formed.

The disk mounting portion 40 and the upper bottom surface 50
Since the synthetic resin material is integrally molded by outsert molding, the flatness and shaft 20 suitable for practical use are sufficiently high.
However, since this portion is made of a synthetic resin, if necessary, cutting of the disk mounting surface 40a and the upper bottom surface 50 with reference to the shaft 20 can be performed very easily and quickly. .

Further, a drive magnet 52 is mounted on the inner peripheral surface 48 of the outer cylindrical portion of the rotor case 18 formed by plastic deformation such as press molding of a magnetic flat plate material, and a stator core 56 fixedly mounted on the outer periphery of the bearing holder 14. Are arranged facing each other so as to orbit around the outer peripheral surface 58 at a predetermined interval. 56a is a stator coil wound around the stator core 56.

In addition, the drive magnet 52 is installed such that the upper end surface 60 is in contact with the upper bottom surface 50 of the synthetic resin integrally formed below the disk mounting portion 40, and the drive magnet 52 is axially moved by the upper bottom surface 50. Is set. That is, the axial relative position of the drive magnet 52 with respect to the open edge 26 of the boss portion 22 of the rotor case 18 is determined. Further, since the outer cylindrical portion 30 is also made of the same material of the magnetic flat plate formed integrally, the drive magnet 5 is directly used.
2 functions as a magnetic shield.

As described above, the rotor case 18 presses the open end edge 26 of the boss portion 22 against the inner ring 28 of the ball bearing 16 whose relative positional relationship is fixed to the base frame 12 so that the base frame 12 Is determined, and the magnetically sensitive element (Hall element) 6 disposed on the printed circuit board 62 mounted on the base frame 12 is determined.
4 is fixed. For this reason, the fluctuation in the magnetic detection amplitude is eliminated, and a stable Hall output is obtained.

Reference numeral 66 denotes a frequency generator, which is provided with a frequency power generating magnetizing portion 70 at the lower edge 68 of the outer cylindrical portion 30 of the rotor case 18, and a frequency power generating pattern (FG pattern) 72 on the corresponding printed circuit board 62. However, the gap d between the surface of the FG pattern 72 and the lower surface of the magnetized portion for frequency power generation 70 facing the surface of the FG pattern 72 can be stably maintained at a predetermined distance.

[0024]

As described above, in the spindle motor according to the present invention, the rotor case is formed by pressing a magnetic plate, and the disk mounting portion is integrally formed of a synthetic resin material, so that the manufacturing cost can be reduced. . Also, since the disc mounting part is made of synthetic resin, it has excellent machinability,
It is easy to secure the accuracy of flatness and verticality with the shaft,
Productivity is improved and high quality products can be provided at low cost.

Further, since the chucking magnet is buried in the recess of the rotor case made of a magnetic material, the leakage magnetic flux can be shielded without providing a yoke, thereby improving the magnetic efficiency of the magnet and reducing the thickness. In addition, since the relative position of the drive magnet in the axial direction with respect to the ball bearing is constant, the axial position does not fluctuate due to the variation in preload, and a stable position detection output and frequency power output can be obtained. The quality control can be performed more easily by such homogenization of the product performance.

[Brief description of the drawings]

FIG. 1 is a sectional view of a spindle motor according to the present invention.

FIG. 2 is a sectional view of a conventional spindle motor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Spindle motor 12 Base frame 14 Bearing holder 16 Ball bearing 18 Rotor case 20 Shaft 22 Boss part 24 Through-hole 26 Opening edge (boss part) 28 Inner ring 30 Outer cylindrical part 32 Annular concave part 34 Chucking magnet 35 Disk 36 Outer edge (annular) Concave part) 40 Disk mounting part 42 Annular mold fixing part 44 Through hole 46 Outer wall (annular concave part) 48 Inner peripheral surface (outer peripheral cylindrical part) 50 Upper bottom surface 52 Drive magnet 56 Stator core 58 Outer peripheral surface 60 Upper end surface 62 Printed circuit board 64 Magnetically sensitive Element (Hall element) 66 Frequency generator 68 Lower edge (peripheral cylindrical part) 70 Magnetized part for frequency power generation 72 Frequency power generation pattern (FG pattern)

Claims (3)

[Claims] 1. A spindle motor comprising: a shaft; a bearing rotatably supporting the shaft; and a rotor case fixed to the shaft and provided with a disk chucking magnet and a disk mounting portion, and integrally rotating. The rotor case is a molded product obtained by plastic deformation of a magnetic plate, the chucking magnet is fixed to a bottom surface of the molded annular concave portion, and the disk mounting portion is formed of a synthetic resin material, and a part thereof is the synthetic resin material. A spindle motor, wherein the spindle motor is integrally fixed to the rotor case so as to extend through the rotor case with a surface formed on a side opposite to the disk mounting portion. 2. A cylindrical portion is formed on an outer periphery of the rotor case, and an end surface of a driving magnet mounted on an inner surface of the cylindrical portion is formed by extending a synthetic resin formed on a side opposite to the disk mounting portion. The spindle motor according to claim 1, wherein the spindle motor is in contact with the surface. 3. The bearing comprises at least one ball bearing, and the rotor case is fitted and fixed to the shaft by an integrally formed boss, and an open edge of the boss is formed on the inner race of the ball bearing. 3. The spindle motor according to claim 1, wherein the spindle motor is pressed against the spindle motor.