JP2000262007A - Disc drive motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a disc drive motor which can achieve the cost reduction and in which ball bearings can be arranged with stable postures. SOLUTION: A frame 20 of a rotary shaft type disc drive motor 1A is a stamping manufactured by applying stamp to a steel plate, etc. Therefore, the finish with the inner diameter, out-of-roundness, etc., of a bearing retaining part 21, which have certain quality level or higher which, cannot be obtained without secondary machining when a casting can be obtained. Since there is no thick part when stamping is employed as the frame 20, although it is necessary to provide a spacer 25 between ball bearing 15 and 17. A bearing outer ring is utilized as the spacer 25.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disk drive motor for rotating a recording disk such as a hard disk. More specifically, the present invention relates to a structure of a hub and its peripheral portion in this type of motor.

[0002]

2. Description of the Related Art As a disk drive motor for rotating a recording disk such as a hard disk, a shaft rotation type in which a disk mounting hub rotates together with a rotating shaft, and a disk mounting hub using a ball bearing There is a fixed shaft type rotatably supported on a fixed shaft via a shaft. In any of these types of motors, the frame and the hub are conventionally made of a casting such as aluminum die casting.

For example, a disk drive motor 1D shown in FIG. 4 is a shaft rotation type motor, and a rotation shaft 113 extending downward from a disk mounting hub 111 and rotatably supports the rotation shaft 113. And a pair of ball bearings 115, 117
Cylindrical bearing holding portion 12 for holding 117 inside
120 on which bearing 1 is formed and bearing holding portion 1
The rotor 111 is roughly composed of a stator core 130 held on the outer peripheral side of the coil 21 and a coil 135 wound around the stator core 130. An annular rotor magnet 112 is mounted on the hub 111 so as to face the stator core 130.
Is fixed through.

[0004] In the disk drive motor 1D shown here, the frame 120 and the hub 111 are aluminum die-cast products, and after forming a blank by casting or the like, dimensional accuracy is obtained by secondary processing such as cutting. Further, in the case where the casting is subjected to secondary processing, it is easy to increase the thickness of the predetermined portion. Therefore, in the frame 120 shown in FIG. 125, and this annular protrusion 125 is formed.
Upper and lower ball bearings 115, 1
By contacting the end surfaces of the outer races 115A and 117A, the ball bearings 115 and 117 are positioned, and a preload is applied to the ball bearings 115 and 117. Also, the central portion 118 of the hub 111
Is thickened to form a shaft holding portion 116 for holding one shaft end of the rotating shaft 113, and a hole 171 is formed in a thick portion around the shaft from below to improve the rotational balance of the hub 111. Adjustments are being made. Further, a minute gap 175 constituting a labyrinth seal is formed between the hub 111 and the bearing holding portion 121 formed on the frame 120 by using the thick portion of the hub 111.

[0005]

However, although there is a strong demand for lowering the cost of the disk drive motor 1D, conventionally, any one of the frame 120 and the hub 111 must be manufactured. Since a casting process and a secondary processing process such as cutting are performed, the frame 120
Also, there is a problem that the cost of the hub 111 itself is high and the cost of the motor cannot be reduced. In addition, there is a problem in that unnecessary material costs are incurred for cutting in the secondary processing. Such a problem is not limited to a shaft rotation type motor, but also applies to a fixed shaft type motor.

[0006] Therefore, in the case of the shaft rotation type motor, the frame 1
It is conceivable that a press-processed product is used for 20 and a press-processed product is used for the hub 111 in the fixed shaft type. However, in such a press-processed product, the outer rings 115 </ b> A, 11 </ b> A of the ball bearings 115, 117 are provided in the bearing holding portion 121.
The protrusion 125 that makes the end face of 7A abut cannot be formed. When a spacer having low dimensional stability or the like is used, the ball bearings 115 and 117 are inclined, and the NPP
Problems such as a decrease in O characteristics occur.

[0007] In view of the above problems, an object of the present invention is to provide:
An object of the present invention is to provide a disk drive motor that can cope with a reduction in cost and can arrange a ball bearing in a stable posture.

[0008]

In order to solve the above-mentioned problems, according to the present invention, there is provided a hub for mounting a recording disk, a rotating shaft extending downward from the hub, and an inner ring fixed to the rotating shaft. A pair of ball bearings, a frame in which a cylindrical bearing holding portion in which an outer ring of the pair of ball bearings is fixed to an inner circumferential surface projects upward, and a stator core held on the outer circumferential side of the bearing holding portion And a coil wound around the stator core, and an annular rotor magnet mounted on the hub so as to face the stator core, wherein the frame has the bearing holding portion facing upward. The plate material is formed by pressing a plate material so as to protrude into a cylindrical shape, and the outer rings of the pair of ball bearings are Characterized in that it is arranged vertically in between the bearing steel ring-shaped spacer fixed to the inner peripheral surface of the ring holder.

In the present invention, the frame is a pressed product manufactured by subjecting a steel plate or the like to press working. If such a pressed product is used, the frame is subjected to secondary processing unlike a cast product. Even if it is not necessary, the inner diameter and roundness of the bearing holding part can be finished with a certain quality or higher. Therefore, there is no need to perform a complicated casting step or a secondary processing step, so that the frame can be manufactured at low cost. Also, material costs can be reduced. Therefore, the cost of the disk drive motor can be reduced. When a pressed product is used as the frame, spacers are arranged because projections cannot be formed in the bearing holding portion. However, if such spacers made of bearing steel are used, the shape stability will be improved. Therefore, the ball bearing is held in a proper posture only by abutting the end surface of the outer ring of the ball bearing. If a spacer made of bearing steel is used, the spacer expands and contracts in the same manner as the outer ring and the bearing ball of the ball bearing even if there is a temperature change, so that the proper posture of the ball bearing can be maintained.

[0010] In the present invention, it is preferable that an annular pedestal having a step formed on an outer peripheral side is mounted on an outer peripheral surface of the bearing holding portion, and a stator core is held on the step of the pedestal. In the present invention, since the frame is manufactured by pressing the plate material, there is no thick portion. Also, as will be described later, the bearing holding portion is formed to be thin to some extent because the ball bearing will not be distorted.
This is advantageous in terms of motor characteristics. Therefore, it is difficult to form a step on which the stator core can be placed on the outer peripheral surface of the bearing holding portion. However, a ring-shaped pedestal is mounted on the bearing holding portion, and the step formed on the outer peripheral side is attached to the mounting portion of the stator core. By using this, it is possible to solve the problem that it is difficult to form a step for mounting the stator core on the outer peripheral surface of the bearing holding portion.

The present invention can also be applied to a fixed shaft type motor. That is, in another embodiment of the present invention, a frame, a fixed shaft rising from the frame, a pair of ball bearings having an inner ring fixed to the fixed shaft, and an outer ring of the pair of ball bearings fixed to an inner peripheral surface. The cylindrical bearing holding portion has a recording disk mounting hub that protrudes downward from the upper surface, a stator core held on the frame, a coil wound around the stator core, and the stator core. In a disk drive motor having an annular rotor magnet mounted on the hub so as to face the hub, the hub is formed by pressing a plate material such that the bearing holding portion protrudes downward in a cylindrical shape. The outer ring of the pair of ball bearings is formed of a pressed product, and the outer ring of the pair of ball bearings is fixed to the inner peripheral surface of the bearing holding portion. Characterized in that it is arranged vertically sandwiched between manufacturing the ring-shaped spacers.

In the present invention, the hub is a pressed product manufactured by subjecting a steel plate or the like to press working, and if such a pressed product is used, the hub is subjected to secondary processing unlike a cast product. Even if it is not necessary, the inner diameter and roundness of the shaft holding portion can be finished with a certain quality or higher. Therefore, there is no need to perform a complicated casting step or a secondary processing step, so that the hub can be manufactured at low cost. Also, material costs can be reduced. Therefore, the cost of the disk drive motor can be reduced. Also, when using a pressed product as the hub,
Since a projection cannot be formed in the bearing holding portion, a spacer is arranged.However, if such a spacer made of bearing steel is used, the shape stability is good, and the end surface of the outer ring of the ball bearing is abutted. The ball bearing is held in a proper posture only by doing so. If a spacer made of bearing steel is used, the spacer expands and contracts in the same manner as the outer ring and the bearing ball of the ball bearing even if there is a temperature change, so that the proper posture of the ball bearing can be maintained.

In the present invention, on the side of the frame,
An annular pedestal having a step formed on the outer peripheral side may be held, and a stator core may be held on the step of the pedestal.

In the present invention, it is preferable that the spacer has a groove formed in an inner peripheral surface in a circumferential direction.

In the present invention, it is preferable to use an outer ring for a ball bearing as the spacer. In this case, the groove is a rolling surface of a bearing ball.

In the present invention, the thickness of the bearing holding portion is preferably smaller than the maximum thickness of the outer race of the ball bearing. In this way, if the thickness of the bearing holding portion is reduced to some extent, even if the accuracy of the inner diameter and roundness of the bearing holding portion is somewhat low, when the ball bearing is mounted inside the bearing holding portion, Even if the bearing holding part side is distorted, the ball bearing is not distorted. Therefore, even if the cost of the motor is reduced by forming the hub by a pressed product, the ball bearing supports the hub in an appropriate posture, so that good motor characteristics can be maintained.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a disk drive according to the present invention will be described with reference to the drawings.

[First Embodiment] FIG. 1 is a half sectional view showing a disk driving motor according to a first embodiment of the present invention.

In FIG. 1, a disk drive motor 1A according to the present embodiment includes a rotating shaft 13 extending downward from a hub 11 for mounting a recording disk, and a pair of ball bearings 15 rotatably supporting the rotating shaft 13. , 17, a frame 20 in which a cylindrical bearing holding portion 21 holding these ball bearings 15, 17 inside protrudes upward from a bottom portion 23, and a stator core 30 held on the outer peripheral side of the bearing holding portion 21. It is roughly composed of a coil 35 wound around the stator core 30 and an annular rotor magnet 12 mounted on the hub 11 so as to face the stator core 30.

In this embodiment, the frame 20 is formed of a pressed product obtained by pressing a plate material such as a steel plate so that the bearing holding portion 21 protrudes in a cylindrical shape. The upper and lower ball bearings 15 and 17 are mounted in the bearing holding portion 21 so as to be positioned vertically above and below the ring-shaped spacer 25. The outer rings 15A and 17A of these ball bearings 15 and 17 are It is adhesively fixed to the inner peripheral surface of the bearing holding portion 21.

The spacer 25 used here is used as an outer ring for a ball bearing. For this reason, there is an advantage that it has high precision in thickness dimensions and the like, and is less expensive than diverting other parts. Also, the upper and lower ball bearings 15, 1
Since the outer races 15A and 17A and the spacer 25 of No. 7 are all formed of the same bearing steel, they have the same thermal expansion coefficient. The spacer 25 has a groove 250 formed in the inner peripheral surface in the circumferential direction.
Numeral 0 corresponds to the rolling surface of the bearing ball, and has a function of retaining the lubricating oil leaked from the ball bearings 15 and 17.

At the bottom portion 23 of the frame 20, near the bearing holding portion 21, a connector 39 for supplying power to the coil 35 wound around the stator core 30 is provided.
Is mounted, and a terminal of the coil 35 (not shown).
Are electrically connected to a flexible wiring board and lead wires (not shown) on the connector 39.

On the outer peripheral side of the frame 20, there is formed a flange portion 29 which is fixed to a chassis of an information recording apparatus or the like on which the motor is mounted by screws or the like.

In this embodiment, since the frame 20 is a press-processed product, there is no extremely thin or thick portion as a whole, but the thickness t1 of the bearing holding portion 21 is not limited to the bottom portion 23 of the frame 20. 0.8 for the wall thickness t2 of
And the ball bearings 15, 17
Are set to be thinner than the maximum thickness t3 of the outer rings 15A and 17A.

Further, since the frame 20 is a press-processed product, there is a restriction that the bearing holding portion 21 cannot be formed thick, and in the present embodiment, as described above, the bearing holding portion 21 is Bottom 23 of
And the outer rings 15A and 17A of the ball bearings 15 and 17 are made thinner. For this reason, a step or the like on which the stator core 30 is placed cannot be formed on the bearing holding portion 21 itself.
A plastic pedestal 40 having a step 41 on the outer peripheral side is attached to an outer peripheral surface of the pedestal 40.
1, the stator core 30 is mounted. The stator core 30 arranged in this manner is fixed by the adhesive 50 applied from the outer peripheral surface of the bearing holding portion 21 to the upper end of the pedestal 40.

In this embodiment, the hub 11 is also a pressed product manufactured by pressing a plate material such as a steel plate, and the cylindrical shaft holding portion 16 protrudes downward from the upper surface 150 by this pressing. Shape. The upper end portion (one shaft end) of the rotating shaft 13 is fitted and fixed to the shaft holding portion 16. Also, the rotating shaft 1
3, the inner rings 15B, 17 of the ball bearings 15, 17 disposed in the bearing holding portion 21
B is adhesively fixed.

Further, at a position below the rotating shaft 13,
A cap 55 is adhesively fixed to the outer end surface of the outer ring 17B of the ball bearing 17, so that the rust preventive used for the ball bearings 15 and 17 is not scattered.

Here, the lower half of the ball bearing 17 projects below the lower surface of the frame 20, and the cap 55 having a side surface 550 is provided for the projecting portion of the ball bearing 17. Is fitted. In addition, the cap 55 has a side surface 5.
The fixing strength of the cap 55 is high because the cap 55 is fixed with the adhesive 59 applied over the outer ring 17 </ b> A of the ball bearing 17 and the lower surface of the frame 20. Also,
Since the cap 55 has the side surface portion 550, the cap 55 can be temporarily fixed at a predetermined position only by covering the lower half of the ball bearing 17 when the cap 55 is attached, so that the motor can be easily assembled.

On the lower surface side of the hub 11, the lower end portion 17 of the shaft holding portion 16 protruding in a cylindrical shape is connected to the upper ball bearing 1.
5 is in contact with the upper end surface of the inner ring 15B, and a preload is applied to the ball bearing 15 so as to press down the inner ring 15B.

A plurality of steps are formed on the upper surface side of the hub 11, and the step surface on the outer peripheral side is a disk mounting surface 18. A screw for fixing a clamp member (not shown) for fixing a hard disk mounted on the disk mounting surface 18 is provided on a step surface formed on the inner peripheral side of the disk mounting surface 18. A hole 110 is formed.

Further, inside the hub 11, the screw holes 1
A plastic ring piece 70 is fixed concentrically to the rotating shaft 13 on the back side of the step surface on which 10 is formed. A hole 71 of a predetermined size for adjusting the rotational balance of the hub 11 is formed at a predetermined position from the lower surface side of the ring piece 70.

The inner peripheral surface 72 of the ring piece 70 faces the outer peripheral surface of the bearing holding portion 21 of the frame 20 and forms a minute gap 75 forming a labyrinth seal with the outer peripheral surface of the bearing holding portion 21. are doing. Further, the ring piece 70 is provided with a protruding portion 77 which protrudes annularly inwardly toward the space between the ball bearing 15 and the hub 11, and the upper surface of the protruding portion 77 is bonded to the lower surface of the hub 11. I have. The lower surface of the projection 77 forms a minute gap 78 that forms a labyrinth seal with the upper end surface of the outer ring 15A of the ball bearing 15.

In the hub 11, a cylindrical side surface portion 119 extends downward from the outer peripheral side of the disk mounting surface 18. The rotor magnet 12 is fixed to the inner peripheral surface of the cylindrical side portion 119, and the rotor magnet 12 is in a state of facing the outer peripheral surface of the stator core 30.

In the disk drive motor 1A configured as described above, in the present embodiment, the frame 20 is a pressed product manufactured by pressing a steel plate or the like. For example, unlike a cast product, even if secondary processing is not performed, the bearing holding portion 21 can be finished with a certain quality or higher in inner diameter, roundness, or inner surface smoothness. Therefore, there is no need to perform a complicated casting step or a secondary processing step, so that the frame 20 can be manufactured at low cost. Also, material costs can be reduced. Therefore, the cost of the disk drive motor 1A can be reduced.

When a pressed product is used as the frame 11, a projection cannot be formed in the bearing holding portion 21, so that the spacer 25 is disposed.
Since such a spacer 25 is made of bearing steel, the shape stability is good. Moreover, since the spacer 25 is an outer ring for a ball bearing, it is inexpensive, has high dimensional accuracy, and has high end surface smoothness. Therefore, the outer ring 15 of the ball bearings 15 and 17
The ball bearings 15, 17 are held in an appropriate posture only by abutting the end faces of A, 17A. Further, since the spacer 25 is made of bearing steel, the outer race 1 of the ball bearings 15 and 17 can be used even if the temperature changes.
Since it expands and contracts in the same manner as 5A and 17A and the bearing ball, the proper posture of the ball bearings 15 and 17 can be maintained, and the preload does not change.

Further, the thickness t1 of the bearing holding portion 21
Is 0.8 with respect to the thickness t2 of the bottom portion 23 of the frame 11.
And less than the maximum thickness t3 of the outer rings 15A, 17A of the ball bearings 15, 17. As described above, since the thickness t1 of the bearing holding portion 21 is reduced to some extent, even if the accuracy of the inner diameter and roundness of the bearing holding portion 21 is slightly lower, the ball bearings 15 and 17 are provided inside the bearing holding portion 21. When the ball bearing 1 is mounted, even if the bearing holding portion 21 side is distorted,
The outer races 15A and 17A of 5 and 17 are not distorted. Therefore, even if the cost of the motor is reduced by forming the frame 20 by a pressed product, it is possible to maintain good motor characteristics such as the ball bearings 15 and 17 supporting the rotating shaft 13 vertically.

Further, in this embodiment, since the frame 20 is manufactured by pressing a plate material, there is no thick portion.
Further, as described above, it is advantageous from the viewpoint of motor characteristics that the bearing holding portion 21 is formed to be thin to some extent. Therefore, it is difficult to form a step on which the stator core 30 can be placed on the outer peripheral surface of the bearing holding portion 21. However, the ring-shaped pedestal 40 is mounted on the bearing holding portion 21, and the step 41 formed on the outer peripheral side is formed. Stator core 30
Since it is used as a mounting portion, the problem that it is difficult to form a step for mounting the stator core on the bearing holding portion 21 of the frame 20 formed by press working can be solved.

Moreover, since the pedestal 40 is made of plastic, even if the vibration when the hub 11 rotates is transmitted to the pedestal 40 via the rotating shaft 13 and the ball bearings 15 and 17, such vibration is transmitted to the pedestal 40. Can be absorbed. Accordingly, since vibration is not easily transmitted to the stator core 30, there is an advantage that the rotational performance of the motor is stable.

In the present embodiment, the hub 11 is also a pressed product manufactured by subjecting a steel sheet or the like to press working. Even without processing, the inner diameter and roundness of the shaft holding portion 16 can be finished with a certain accuracy or higher. Therefore,
Since there is no need to perform a complicated casting step or a secondary processing step, the frame 20 can be manufactured at low cost. Also, material costs can be reduced. Therefore, the cost of the disk drive motor 1 can be reduced.

When a pressed product is used as the hub 11, there is no thick portion, and the thick portion is used to adjust the rotation balance of the hub 11 and to form the minute gap 75 forming the labyrinth seal. However, if the ring piece 70 is fixed to the inside of the hub 11 as in the present embodiment, the hub 1 can be formed using the ring piece 70.
This makes it possible to adjust the rotational balance and to form the minute gap 75 constituting the labyrinth seal. Therefore, even in the case of the hub 11 manufactured by press working, good rotation balance can be maintained, and scattering of lubricating oil and the like from the ball bearings 15 and 17 can be prevented. In this case, since the hub 11 is a pressed product and is thin as a whole, there is sufficient space for fixing the ring piece 70 inside, and even if such a ring piece 70 is fixed to the hub 11, the motor There is no hindrance to miniaturization. Moreover, since the ring piece 70 is a plastic molded product, it is inexpensive and lightweight.

[Second Embodiment] FIG. 2 is a half sectional view showing a disk driving motor according to a second embodiment of the present invention. The disk drive of this embodiment is of a fixed-shaft type, but has portions common to the first embodiment. Therefore, corresponding portions are denoted by the same reference numerals.

In FIG. 2, the disk drive motor 1B of this embodiment includes a frame 20 having a cylindrical shaft holding portion 22 protruding from a bottom portion 23, a fixed shaft 19 held by the shaft holding portion 22, and a fixed shaft 19. 19, a pair of ball bearings 15, 17 held by
17, a recording disk mounting hub 11 rotatably supported on a fixed shaft 19, a stator core 30 held on the outer peripheral side of a shaft holding portion 22, and a coil 35 wound around the stator core 30. , An annular rotor magnet 1 mounted on the hub 11 so as to face the stator core 30
2 is roughly constituted.

In this embodiment, the frame 20 is formed of a pressed product obtained by pressing a plate material such as a steel plate so that the shaft holding portion 22 protrudes in a cylindrical shape.

On the bottom portion 23 of the frame 20, near the shaft holding portion 22, a connector 39 for supplying power to the coil 35 wound around the stator core 30 is mounted. An outer peripheral side of the frame 20 is formed with a flange portion 29 which is fixed to a chassis of an information recording device or the like on which the motor is mounted by screws or the like.

In this embodiment, since the frame 20 is a pressed product, there is no extremely thin or thick portion as a whole, but the thickness of the shaft holding portion 22 is larger than the thickness of the bottom portion 23. Although it is thin, unlike the bearing holding portion of the first embodiment, it can be formed to be slightly thicker.
A step 220 on which the stator core 30 is placed is formed, and the stator core 30 pressed into the shaft holding section 22 is held on the step 220.

In this embodiment, the hub 11 is also a cup-shaped press-formed product in which a plate material such as a steel plate is pressed so that the opening faces downward.

In the hub 11, the cylindrical bearing holding portion 100 protrudes downward from the upper surface 150 thereof. The ball bearings 15 and 17 are vertically arranged in the bearing holding portion 100 with an annular spacer 25 interposed therebetween.
A and 17A are adhesively fixed to the inner peripheral surface of the bearing holding unit 100.

The spacer 25 used here is used as an outer ring of a ball bearing. For this reason, there is an advantage that it has high precision in thickness dimensions and the like, and is less expensive than diverting other parts. Also, the upper and lower ball bearings 15, 1
The outer rings 15A, 17A and the spacer 25 of No. 7 are all made of the same bearing steel, and therefore have the same thermal expansion coefficient. Therefore, even if there is a temperature change, the outer rings 15A, 1A of the upper and lower ball bearings 15, 17
7A and the spacer 25 perform similar expansion and contraction.
The spacer 25 has a groove 250 formed in the inner peripheral surface in the circumferential direction. The groove 250 corresponds to a rolling surface of a bearing ball.
It has a function of retaining the lubricating oil leaked from the fuel cell 17.

In the present embodiment, since the hub 11 is a press-processed product, there is no extremely thin or thick portion as a whole, but the thickness t11 of the bearing holding portion 100 is 0.1 for a thickness t12 of 150.
8 times or less and the ball bearings 15, 1
7 is set to be thinner than the maximum thickness t3 of the outer races 15A and 17A.

A fixed shaft 19 is inserted inside the ball bearings 15, 17, and the inner rings 15 B, 15 B of the ball bearings 15, 17 are attached to the outer peripheral surface of the fixed shaft 19.
17B is adhesively fixed. Here, the upper ball bearing 15 has an upper half protruding from the upper end surface of the hub 11, and extends from the outer end surface of the outer ring 15 </ b> A of the ball bearing 15 to the outer peripheral surface at a position above the fixed shaft 19. A cap 56 having a side surface portion 560 is bonded and fixed to the ball bearing so that the rust preventive used for the ball bearings 15 and 17 is not scattered. Here, the adhesive 58
Is the side surface portion 560 of the cap 56, the ball bearing 15
Is applied over the outer peripheral surface of the outer ring 15A and the upper end surface of the hub 11, so that the adhesive strength of the cap 56 is high. Further, since the cap 56 has the side surface portion 560, when the cap 56 is attached, it can be temporarily fixed at a predetermined position only by covering the upper half portion of the ball bearing 15, so that the motor can be easily assembled.

The hub 11 is a press-processed product. The upper surface of the hub 11 has a plurality of steps similar to a conventional hub, and the step surface on the outer peripheral side is a disk mounting surface 18. A screw hole 110 for fixing a clamp member (not shown) for fixing a hard disk mounted on the disk mounting surface is formed on a step surface formed inside the disk mounting surface 18. Is formed. However, hub 1
1 is a pressed product, so that there is no thick portion enough to form a hole for adjusting the rotational balance of the hub 11.

Therefore, in the present embodiment, a plastic ring piece 70 is adhered and fixed concentrically with the fixed shaft 19 by utilizing a concave portion formed inside the hub 11, and a hole 71 is formed in the ring piece 70 from below. Forming the hub 11
Adjustment of the rotation balance.

In the hub 11 as well, the cylindrical side surface portion 119 extends downward from the outer peripheral side of the disk mounting surface 18.
Is extending. The rotor magnet 12 is fixed to the inner peripheral surface of the cylindrical side surface portion 119.
Is in a state of facing the outer peripheral surface of the stator core 30.

In the disk driving motor 1B thus configured, the hub 11 is a pressed product manufactured by pressing a steel plate or the like. Unlike the product, the inner diameter and the roundness of the bearing holding portion 100 can be finished with a certain accuracy or more without performing the secondary processing. Therefore, there is no need to perform a complicated casting process or a secondary processing process, so that the hub 11 can be manufactured at low cost. Also, material costs can be reduced. Therefore, the cost of the disk drive motor 1 can be reduced.

When a pressed product is used as the hub 11, a projection cannot be formed in the bearing holding portion 100, so that the spacer 25 is disposed. Since the material is used, the shape stability is good. Moreover, since the spacer 25 is an outer ring for a ball bearing, it is inexpensive, has high dimensional accuracy, and has high end surface smoothness. Therefore, the outer ring 15 of the ball bearings 15 and 17
The ball bearings 15, 17 are held in an appropriate posture only by abutting the end faces of A, 17A. Further, since the spacer 25 is made of bearing steel, the outer ring 1 of the ball bearings 15 and 17 can be used even if the temperature changes.
Since it expands and contracts in the same manner as 5A and 17A and the bearing ball, the proper posture of the ball bearings 15 and 17 can be maintained, and the preload does not change.

When a pressed product is used as the hub 11, since there is no thick portion, it is difficult to adjust the rotation balance of the hub 11 by using the thick portion. If the ring piece 70 is fixed to the inside of the hub 11 as in the present embodiment, the rotation balance of the hub 11 can be adjusted using the ring piece 70. In this case, since the hub 11 is a pressed product and is thin as a whole, there is sufficient space for fixing the ring piece 70 inside, and even if such a ring piece 70 is fixed to the hub 11, the motor There is no hindrance to miniaturization.

Further, the thickness t of the bearing holding portion 100
11 is not more than 0.8 times the thickness t12 of the upper surface 150 of the hub 11 and has a ball bearing 15;
It is thinner than the maximum thickness t3 of the 17 outer rings 15A and 17A. As described above, since the thickness t11 of the bearing holding portion 100 is reduced to some extent, the bearing holding portion 100
Even if the accuracy of the inner diameter and roundness of the ball bearings are slightly lower, the outer ring of the ball bearings 15 and 17 may be distorted when the ball bearings 15 and 17 are mounted inside the bearings. 15A and 17A are not distorted. Therefore, even if the cost of the motor is reduced by forming the hub 11 by a pressed product, the ball bearings 15 and 17 can maintain good motor characteristics such as supporting the hub 11 in an appropriate posture. .

Further, in the present embodiment, the frame 20
Is a pressed product manufactured by subjecting a steel plate or the like to press working. If such a pressed product is used, unlike the cast product, the shaft holding portion 22 can be formed without performing secondary processing. Finish with a certain degree of quality in terms of inner diameter, roundness, etc. Therefore, since it is not necessary to perform a complicated casting process or a secondary processing process, the frame 20 can be manufactured at low cost. Also, material costs can be reduced. Therefore, the cost of the disk drive motor 1B can be reduced.

Further, in the case of the fixed shaft type, unlike the rotary shaft type motor (Embodiment 1), no ball bearing is mounted inside the frame 20. It may be formed thick. Therefore,
Since the step 220 can be formed on the outer peripheral surface of the shaft holding portion 22, the step 220 can be used for mounting the stator core.

[Modification of Second Embodiment] FIG. 3 is a half sectional view showing a disk drive motor according to a modification of the second embodiment of the present invention. Since the basic structure of the disk drive motor of the present embodiment is almost the same as that of the second embodiment, the corresponding parts are denoted by the same reference numerals and the description thereof is omitted.

In FIG. 3, the disk driving motor 1C according to the present embodiment also has a cylindrical shaft holder 2 similar to the second embodiment.
The frame 20 from which the base 2 protrudes from the bottom 23 and the shaft holding unit 2
2, a pair of ball bearings 15 and 17 held by the fixed shaft 19, and a recording disk mounted rotatably supported by the fixed shaft 19 via these ball bearings 15 and 17. Mounting stator 11, a stator core 30 held on the outer peripheral side of the shaft holding part 22, a coil 35 wound around the stator core 30, and an annular rotor mounted on the hub 11 so as to face the stator core 30. And a magnet 12.

Also in this embodiment, the frame 20 and the hub 11 are formed of a pressed product in which a plate material such as a steel plate is pressed so that the shaft holding portion 22 and the bearing holding portion 100 protrude in a cylindrical shape. . Hub 1
The rotation balance of the hub 11 is adjusted using a plastic ring piece 70 fixed to the inside of the hub 1.

In this embodiment, since the thickness of the shaft holding portion 22 is designed to be thin, the stator core 3 is attached to the shaft holding portion 22 itself.
Although a step for mounting 0 cannot be formed, in this embodiment,
A plastic pedestal 40 having a step 41 on the outer peripheral side is press-fitted and fixed to the outer peripheral surface of the shaft holding portion 22, and the stator core 30 press-fitted and fixed to the pedestal 40 is mounted on the step 41 of the pedestal 40. I have. Therefore, even if the frame 20 is formed of a pressed product, the stator core 30
There is no hindrance to the retention. In addition, since the pedestal 40 is made of plastic, even if vibrations when the hub 11 rotates are transmitted to the pedestal 40 via the fixed shaft 19 and the shaft holding portion 22, such vibrations can be absorbed by the pedestal 40. Can be. Accordingly, since vibration is not easily transmitted to the stator core 30, there is an advantage that the rotational performance of the motor is stable.

Further, in this embodiment, the cylindrical portion 44 extends upward from the pedestal 40, and the cylindrical portion 44 projects between the outer ring 17 A of the lower ball bearing 17 and the lower portion from the hub 11. Bearing holding part 10
Small gaps 73 and 74 that form a labyrinth seal are formed between the lower end of the zero and the lower end. Therefore, when a pressed product is used as the frame 20, since there is no thick portion, it is difficult to form a minute gap forming the labyrinth seal using this thick portion. If a ring-shaped separate member called the pedestal 40 is used as described above, the pedestal 40 can be used to form the minute gaps 73 and 74 constituting the labyrinth seal.

[0065]

As described above, according to the present invention, in a shaft-rotating type or fixed-shaft type disk drive motor, a frame or a hub is formed by pressing a steel plate or the like. With such a pressed product, unlike a cast product, the inner diameter and the roundness of the bearing holding portion can be finished with a certain quality or higher without performing secondary processing. Therefore, it is not necessary to perform a complicated casting step or a secondary processing step, so that the frame and the hub can be manufactured at low cost. Also, material costs can be reduced. Therefore, the cost of the disk drive motor can be reduced. In addition, when a pressed product is used as the frame or hub, a projection cannot be formed in the bearing holding portion, so a spacer is arranged.If such a spacer is made of bearing steel, Since the shape stability is good, the ball bearing is held in an appropriate posture only by bringing the end surface of the outer ring of the ball bearing into contact. If a spacer made of bearing steel is used as the spacer, it expands and contracts in the same manner as the outer ring of the ball bearing or the bearing ball even if there is a temperature change, so that the proper posture of the ball bearing can be maintained.

[Brief description of the drawings]

FIG. 1 is a half sectional view of a disk drive motor according to a first embodiment of the present invention.

FIG. 2 is a half sectional view of a disk drive motor according to a second embodiment of the present invention.

FIG. 3 is a half sectional view of a disk drive motor according to an improved example of the second embodiment of the present invention.

FIG. 4 is a half sectional view of a conventional disk drive motor.

[Explanation of symbols]

1A, 1B, 1C Disk drive motor 11 Hub for mounting recording disk 12 Rotor magnet 13 Rotary shaft 14 Yoke 15, 17 Ball bearing 15A, 17A Outer ring of ball bearing 15B, 17B Inner ring of ball bearing 16 Hub holding part of hub Reference Signs List 17 Lower end portion of hub shaft holding portion 18 Disk mounting surface 19 Fixed shaft 20 Frame 21 Frame bearing holding portion 22 Frame shaft holding portion 23 Frame bottom 25 Spacer 29 Flange portion 30 Stator core 35 Coil 39 Connector 40 Pedestal 41 Pedestal 44 Cylindrical portion 55 of pedestal 55, 56 Cap 70 Ring piece 73, 74, 75, 78 Minute gap constituting labyrinth seal 100 Bearing holding portion of hub 150 Upper surface portion of hub 250 Groove of spacer 550, 560 Cap Side

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5H019 AA00 AA09 AA10 CC04 CC08 CC09 DD01 EE11 EE14 FF03 5H605 AA00 BB05 BB19 CC01 CC03 CC04 CC05 DD03 EA06 EB10 EB17 EB33 FF01 GG12 GG14 GG16

Claims (7)

[Claims] 1. A hub for mounting a recording disk, a rotating shaft extending downward from the hub, a pair of ball bearings having an inner ring fixed to the rotating shaft, and an outer ring of the pair of ball bearings having an inner periphery. A frame in which a cylindrical bearing holding portion fixed to the surface protrudes upward, a stator core held on the outer peripheral side of the bearing holding portion, a coil wound around the stator core, and faces the stator core. A disk drive motor having an annular rotor magnet mounted on the hub as described above, wherein the frame is formed by pressing a plate material such that the bearing holding portion protrudes upward in a cylindrical shape. And the outer races of the pair of ball bearings are formed of bearing steel rings fixed to the inner peripheral surface of the bearing holding portion. Motor disk drive, characterized by being arranged vertically in between Jo the spacers. 2. The method according to claim 1, wherein an annular pedestal having a step formed on an outer peripheral side is mounted on an outer peripheral surface of the bearing holding portion, and a stator core is held on the step of the pedestal. Characteristic disk drive motor. 3. A frame having a frame, a fixed shaft erecting from the frame, a pair of ball bearings having an inner ring fixed to the fixed shaft, and a cylindrical shape having an outer ring of the pair of ball bearings fixed to an inner peripheral surface. A bearing for mounting a recording disk, the bearing holding portion of which protrudes downward from the upper surface, a stator core held on the frame, a coil wound on the stator core, and the stator core facing the stator core. A disk drive motor having an annular rotor magnet mounted on a hub, wherein the hub is formed of a press-formed product obtained by pressing a plate material so that the bearing holding portion protrudes downward in a cylindrical shape. And the outer races of the pair of ball bearings are ring-shaped rings made of bearing steel fixed to the inner peripheral surface of the bearing holding portion. Motor disk drive, characterized by being arranged vertically in between the p o. 4. An annular pedestal according to claim 3, wherein an annular pedestal having a step formed on an outer peripheral side is held on the side of the frame,
A disk drive motor, wherein a stator core is held on the step of the pedestal. 5. The method according to claim 1, wherein
The disk drive motor according to claim 1, wherein the spacer has a groove formed in an inner peripheral surface in a circumferential direction. 6. The disk drive motor according to claim 5, wherein the spacer is an outer race for a ball bearing, and the groove is a rolling surface of a bearing ball. 7. The method according to claim 1, wherein
The disk driving motor according to claim 1, wherein a thickness of the bearing holding portion is smaller than a maximum thickness of an outer ring of the ball bearing.