JPH03168980A - Oscillation motor for accessing head - Google Patents

Abstract

PURPOSE:To eliminate thermal deformation and to suppress the generation of a thermal off-track by adding a radial direction load on a rotor and providing a spacing between a bearing and the bearing box of the motor. CONSTITUTION:The other side of a magnet 14 of the rotor 13 is provided with a yoke 20 mounted with a coil 19 on the inner peripheral surface thereof. Torque is generated when an electric current is passed to the coil 19. Magnetic attraction force is acted radially by the permanent magnet 14 and the load is applied on the rotor 13. The clearance is provided between the bearing 12 and the bearing box 13a of the rotor 13 to deviate the centers of the rotor 13 and the bearing 12. This spacing is set the same even at the upper and lower bearings 12 and the radial load is applied uniformly on the bearing 12. The structure in which deformation is hardly generated even in the coupling part of different metals, such as the rotor 13 and the bearing 12 is then obtd. even if the ambient temp. changes. The generation of the thermal off-track is thus suppressed.

Description

[Detailed Description of the Invention] [Summary] Regarding the head access swing motor that accesses the read/write area of a data storage disk device, the thermal off of the head is achieved by devising the structure of the head access swing motor. 1. Aiming at reducing the number of racks, a shaft and a bearing that rotatably support the rotor, an arm that protrudes from the U and attaches a read/write head to its tip, and a permanent magnet that drives the rotor. and a set of coils, the rotor is provided with means for applying a radial load to the rotor, and a gap is provided between the bearing and the rotor's bearing box or the shaft. , [Industrial Application Field] The present invention is applicable to the reading and writing of external storage devices such as computers, magnetic disk devices, optical disk devices, etc. used in 1.2.
-Related to a head access swing motor for accessing the throat.

In recent years, disk devices such as magnetic disks and optical disks have been used as external storage devices for computers, and rotary positioners have become widespread as actuators that move the heads that read and write data to and from these disk devices. (This is because it allows for a relatively compact design and is simple in structure.

For example, in a hard disk drive that uses magnetic disks as two recording media, . A positive motor is used.

The density of magnetic disk drives has been increasing year by year, and recently the recording density in the track direction has reached 2000 TP.
I (the number of tracks per inch is 2000), and the 1-rack pitch in this case is only 12 μm. A major problem when implementing such a device is thermal off-track, a phenomenon in which temperature changes cause the i-rack position to shift between the servo head and a large number of data heads. It is desired to reduce the number of l.racks.

[Conventional technology]

FIG. 10 is a plan view of an example of a conventional general hard disk drive. 3600rp for hard disk drive
There is a spindle S that rotates at high speed (5400 rpm recently), and this spindle S has a plurality of sheets (for example, 10
2) magnetic disks D are attached at predetermined intervals. The magnetic disk D has data recorded on both sides thereof, and writing to the magnetic disk and reading from the magnetic disk are performed by magnetic heads 1 installed on both sides of the magnetic disk D. It will be done. The movement of this magnetic head H over the magnetic disk D is performed by an actuator via an arm A. Actuator for moving the magnetic head H. There are two types of Eta: linear type and drawing type.
A swinging type, not shown in FIG. 10, is often used.

Generally, a swing motor SM is used in the swing actuator, which can rotate (swing) only within a predetermined angle, and can finely control the rotation angle. This oscillating rotor SM is composed of a stator ST and a coater R.
The rotor R has the same number of magnetic disks D attached to the spindle S, or one more than the number of magnetic disks D.
More or fewer arms A are provided protrudingly. A magnetic head assembly ASSY having two magnetic heads H mounted facing each other so as to sandwich a magnetic disk D is attached to the tip of this arm 8. The stator ST of the drawing motor SM is a magnetic disk D.
An arm A installed near the stator ST and protruding from the stator ST
Magnetic head assembly attached to the tip of
The moving range α of the magnetic head H of SY coincides with the recording area C2 of the magnetic disk D. Note that one of the many heads is used as a servo head.

The swing motor, which is the actuator for driving and accessing the magnetic parts of such hard disk drives, generally has a so-called moving coil, which has a permanent magnet in the stator and a coil on the rotor side. Type motors are the mainstream, but there are also attempts to adopt so-called moving magnet type motors, which have a coil on the stator side and a permanent magnet on the rotor side (see Japanese Patent Publication No. 35181/1981). 2Figure 9(a). (t)) shows an example of this movable magnet type rocking motor, and shows an example of an outer ring rotating type rocking motor. A fixed shaft 91 is fixed to the stator 98, and a rotor 92 is rotatably attached to the fixed shaft 91 via a bearing 97 such as a bearing. A permanent magnet 95 is attached to. A coil 94 is attached to the inner surface of the stator 98 facing the permanent magnet 95. In this case, the coil attachment parts of the rotor 92 and stator 98 are generally made of a magnetic material such as carbon steel or martensitic stainless steel, and also serve as a yoke, and when the coil 94 is energized, the rotor 92 is attached to the fixed shafts 1 and 91. oscillates around.

Recently, in order to perform high-speed access, arm 93
There is a need to reduce the weight of the eyelets 92, and these are often made of lightweight metals such as aluminum alloys, magnesium alloys, etc. in addition to being integrated.

[Problem that the invention attempts to solve]

By the way, in the conventional head access swing motor constructed as described above, the arm 93 and rotor 92 are integrated to reduce weight, and are made of aluminum alloy,
Bearings 97 are generally made of steel, whereas they are manufactured from lightweight metals such as magnesium alloys, and are functionally
The outer ring of the bearing 97 and the bearing box of the rotor 92 (the inner circumferential portion that accommodates the outer ring of the bearing 97 of the rotor 92) need to be fixed, and these are generally fitted by means such as adhesive or press fitting. . Then, when the ambient temperature changes, thermal stress is generated at the joint between the rotor 92 and the bearing 97 because the coefficient of thermal expansion is different between light alloys such as Al and steel (Al is more than twice as large). , there is a problem that the entire rotor is thermally deformed and a normal off-track occurs.

An object of the present invention is to solve the problem of the thermal off I/rack in the conventional swing motor for head access, and to have a structure in which thermal deformation does not easily occur even in the above-mentioned joints of dissimilar metals even when the ambient temperature changes. Thermal off 1
- An object of the present invention is to provide a head access swing motor that can suppress the occurrence of racks.

[Means for Solving the Problems] FIG. 1 shows the principle structure of a swing motor for head access according to the present invention that achieves the above object.

As shown in FIG. 1, in the present invention, a fixed shaft 1,
A rotor 2 is rotatably supported by the fixed shaft l-1 via a bearing 7, an arm 3 that protrudes from the rotor 2 and has a read/write head (not shown) at its tip, and a permanent magnet that drives the rotor 2. and a set of coils (not shown because the mounting positions are various).A rocking motor for access is equipped with a means for applying a load in the radial direction shown by the arrow to the rotor 2. , and a gap is provided between the bearing 4 and the bearing box 5 of the rotor 2 or the shaft l.

[Function] According to the swing motor for head access of the present invention, even if the surrounding environmental temperature changes and the aluminum and steel are thermally deformed with different expansion coefficients, the thermal deformation is caused by the rotor. Since the thermal stress is absorbed by the gap between the bearing box and the bearing, no thermal stress is generated at the joint between the rotor and the bearing, and the entire rotor is not thermally deformed, suppressing thermal off-track due to temperature changes. .

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

3 and 4 are a plan view and a sectional view showing the structure of an embodiment of the head access drawing screen 10 of the present invention. Although the housing is omitted in this embodiment, there is a fixed shaft 11 inside the base and cover of the housing.
is fixed by Pol 1 etc. Further, in the plan view of FIG. 3, seal members, rings, springs, etc. are omitted in order to clarify the fitting between the bearing and the rotor, which will be described later.

The central part of the fixed shaft +-ii is bulged to form a large diameter part with a thick diameter, and the upper and lower parts thereof are small diameter parts. A rotor 13 is rotatably held in this narrow diameter portion via a bearing 12 such as a ball bearing, and the bearing mounting portion of the rotor 13 has a large inner diameter.
The inner workings of the rotor 13 that faces the large diameter parts of the fixed shafts 1 and 11! n. The rotor 12 has a plurality of permanent magnets 14 on the side opposite to the magnetic disk.
are arranged, and arms l5 corresponding to the number of magnetic disks protrude from the magnetic disk side.

A seal member 16 is attached to the fixed shaft 11 so as to sandwich the two bearings 12, and the contact portion between the seal member 16 and the inner peripheral surface of the l cork l3 functions as a magnetic fluid seal. In addition, a preload spring 8 is interposed between the lower surface of the sealing member l6 and the support holder 12, and the preload spring 18 of the upper bearing l2 causes the slider ring 17 to rotate in the axial direction. Preload is applied. The sealing member 16 is provided with a slot guard to prevent grease and the like from the bearing 12 from getting into the enclosure of the magnetic disk.

A coil 19 is placed on the outside of the magnet 14 of the rotor 13.
There is a yoke 20 which is attached to the inner circumferential direction, and generates 1.0 lux by passing a current.

At this time, in this embodiment, a magnetic attraction force is exerted in the radial direction by the permanent magnet 14. The magnitude F of this attraction force is μ
. where is the magnetic permeability in vacuum, Bg is the gap magnetic density, and A is the area, F=A-Bν/2μ.

When roughly calculated assuming that Bg=7kg, bearing 1 {1
It is a fairly large force of 8 kg per 7i1.

The rotor-rotating type of the present invention shown in the above embodiments...
- In the throat access swing motor, the attraction force by the magnet 14 acts on the side opposite to the head. Therefore, this Example 7
The outer ring of the bearing 12 and the rotor 13 are shown in Figure 3.
Axis 5! - Wi 1 3 a with a clearance fit. In reality, the gap between the outer ring of the bearing 12 and the bearing box 13a of the rotor 13 is 2 to = -3 6 at room temperature, taking into account low temperatures.
It has a tightening margin of m. The gap should be

(2) If the outer ring of the bearing I2 and the bearing ring 13a of the bearing l3 are simply fitted with a clearance, the outer ring of the bearing I2 and the rotor l3 will be caused by the radial attraction force of the magnet 14a mentioned above. The bearing box 13a is in circle-to-circle contact, and the contact point is not stable, and in particular, the position tends to be unstable with respect to the direction perpendicular to the suction force.

Therefore, in this embodiment, a recess 21 is provided on the arm side of the bearing box 13a of the rotor 13, as shown in FIG.
A point A where the recess 21 and the bearing box 13a of the rotor 13 intersect,
The outer ring of the bearing 12 is brought into contact at two points B, and lateral play is eliminated by bearing the concentrated load at the two points.

Basically, the shape of this recessed portion 2l may be any shape, but between the points A and B mentioned above and the bearing box 13a of the rotor 13,
It is desirable that the angle ρ between the center point C and the center point C is about 90 to 120 degrees. When providing the four portions 21, the most suitable method is to provide two circles with different radii eccentrically. this is,. The points A and 13, where the four parts 21 and the bearing box 13a of the rotor 13 intersect, are not shifted in the same direction, and the vicinity of points A and B are continued as smoothly as possible to avoid local stress concentration and reduce the load. This is because the burden can be covered as widely as possible.

The shapes of the aforementioned four parts 21 are made to be exactly the same in the two lower drawers 12. As a result, the radial load is almost equal to both bearings 12.
is applied evenly, so if there is a temperature change, rotor 1
3 moves in a direction parallel to the fixed shaft l1, and the load change is small, so 5 thermal off-track will not occur. Also, even if it is a clearance fit in the radial direction, it is undesirable to have large play in the axial direction.
This backlash is reduced by the ring 17 described above.

In this embodiment, the swing motor for head access is configured as shown below, thereby reducing the amount of manual override and rack. Figure 5 shows the amount of thermal off-track caused by the rocking motor for access of the present invention configured as shown in Figures 3 and 4, and Figure 6 shows the amount of thermal off track caused by the rocking motor for access of the present invention configured as shown in Figures 3 and 4. This shows the amount of thermal off-track of the swing motor for head access, and the off-track scale of all heads is plotted against ZARBO and TUDO. As can be seen from a comparison between FIG. 5 and FIG. 6, the off-track, which was initially about 4 μm, can be reduced to less than 1 μm by the swing motor for accessing the base of the present invention. In this way, the rocking motor for direct access of this embodiment makes it possible to avoid reducing the amount of thermal off-track, thereby realizing a magnetic disk device with higher recording density and more reliability. be able to.

FIGS. 7 and 8 show an embodiment in which the present invention is implemented using a moving coil type swing motor.

In the moving coil type swing motor, an arm 73 corresponding to the number of magnetic disks D is attached to a rotor 72 that swings around a fixed shaft 71. The attached magnetic head 74 reads from and writes to the magnetic disk opening. A coil support plate 75 is provided on the back side of the mounting surface of the arm 73 of the rotor 72, and a permanent magnet 7 is attached to the coil 76 supported by the coil support plate 75.
The swing motor is constructed with the stay 77a removed and the stay 77b forming a yoke inserted. Then, by energizing the coil 7 (3), the rotor 7
2 swings, and the magnetic head 74 accesses the magnetic disk IM).

, In the second embodiment B, the support box 72a of the first part 72 that accommodates the support receiver 78 is provided with the same seven four parts as in the previous embodiment, and has a recess 79 and a sleeve support box 72a. Boundary 12 lines A, B
The load is received from the train wheel of the bearing 78. In this embodiment, as shown in FIG. is used only for adding preload.

That is, the bearings 78 at both ends of 8 are normal bearings Z, and receive loads in the radial direction and the axial direction. On the other hand, in this embodiment, the third support holder 80 has a fixed shaft l.7 in the inner ring of the pamo.
1, and the outer ring is in a state where it can rotate to 0El1. Then, the outer ring of this free bearing 80 is attached to the rotor 72.
It is biased from the side by a spring 81, and as a reaction, the rotor 7
2 is L7 so as to apply a load in the axial direction similar to the previous embodiment. This spring 81 can be inserted into the width of a horizontal hole 82 provided in the side surface of the rake 72, and then cooled with a plug 83 on the far side.

In the above embodiment, the inner ring of the third ω bearing 80 is fixed to the fixed shaft 71, the outer ring is allowed to rotate freely, and the outer ring of the third ω bearing 80 is attached to the spring 81 from the rotor 72 side.
energized by, and its reaction. ! Next, the rotor 72 is configured to apply a load in the axial direction similar to the previous embodiment, but conversely, the outer ring of the third bearing 80 is placed in the bearing box 72a.
, the inner ring is in a state where it can rotate on its own, and the inner ring with zero thickness is biased by a spring from the fixed shaft 1/71 side, and as a reaction, an axial direction is applied to the roke 72 similar to the previous embodiment. j7 may also be used to apply a load.

Generally, when using two or more bearings, accuracy etc. are difficult, but the third bearing 80 in the following 12 embodiments is only for preloading, and the outer ring or inner ring is a loose fit.
There are no problems with accuracy (71. Also, the center of the fixed shaft is generally free, and the natural frequency of the shaft 1 tends to be a problem, but with this moving coil type head access In the embodiment of the swing motor for the fixed shaft L, the central part of the fixed shaft L is pressed by a spring.
A damper effect can be expected, and the shaft 1・ω natural vibration is reduced. In addition, if it is desired to emphasize this damper effect, it is preferable to use a preload using rubber or the like rather than a coil spring.

The above is a case in which the third bearing is used merely for adding preload, but it is also possible to use the third bearing more actively as a radial bearing. In this case, the gap between the third bearing outer ring and the lower bearing box should be made smaller, and the radial clearance of the bearing should be larger, so that when preload is applied, the bearing outer ring Just make sure it touches the box. In this case, the third bearing acts as a radial bearing, resulting in a true three-bearing configuration, reducing the bearing stiffness by -1. Gerukoyoka can raise the resonance point of the red system.

In the above-mentioned embodiment, the third shaft cost is one, but the number of third shaft bearings is not limited to two, and a plurality of third bearings can be installed in a fixed shaft. It is also possible to preload these by installing them.

In addition, in order to distribute the concentrated load at two points, the bearing box on the rotor side may be formed into an elliptical shape, in addition to providing the recess shown in the above embodiment.

〔Effect of the invention〕

As explained above, the oscillating sweater for access according to the present invention has a structure that does not easily cause thermal deformation even when the ambient temperature changes, even at the joints of dissimilar metals such as the rotor and bearing. If realized, it will have the effect of suppressing the occurrence of thermal off-track.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the principle structure of the rocking motor for access of the present invention, Fig. 2 is a diagram illustrating the four parts provided in the bearing box of the rotor, and Figs. 3 and 4 are the movable magnets of the present invention. 5 is a diagram showing the amount of thermal off-track by the swing motor for head access of the present invention, and FIG. 6 is a diagram showing the amount of thermal off-track by the swing motor for head access of the present invention. 7 and 8 are diagrams showing the amount of thermal off-track by the motor, and FIGS.
Figure (a). (b) is a horizontal cross-sectional view and a vertical cross-sectional view of a conventional movable magnet type head access swing Tanabata, and FIG. 10 is a plan view of an example of a conventional hard disk device. DESCRIPTION OF SYMBOLS 1... Fixed shaft, 2... Rotor, 3... Arm, 4... Bearing, 5... Bearing box, 6... Recess, 1
0... Movable magnet type head access swing motor according to an embodiment of the present invention, 11... Fixed shaft, 12... Bearing, 13... Rotor, 14... Permanent magnet, 15...・
・Arm, 19...Coil, 20...Yoke, 71
... fixed shaft, 72 ... rotor, 73 ... arm, 74 ... head, 75 ...: 7 illumination support plate, 7 6.1" coil, 77a ... permanent magnet, 77
... Yoke, 78 ... Bearing, 79 ... Recess, 80
...Third bearing, 81...Spring.

Claims (1)

[Claims] 1. A head access swing motor for accessing a read/write head of an external storage device equipped with a rotating disk, which comprises a shaft (1) rotatably supporting a rotor (2) and a bearing (
4), an arm (3) protruding from the rotor (2) for attaching a read/write head to the tip thereof, and a permanent magnet and coil set for driving the rotor (2), A means for applying a load in a radial direction to the rotor (2) is provided, and a gap (6) is provided between the bearing (4) and the bearing box (5) of the rotor (2) or the shaft (1).
) A swing motor for head access, characterized in that it is provided with: 2. The head access rocker according to claim 1, wherein the means for applying a load in the radial direction to the rotor (2) comprises a permanent magnet provided on the rotor (2) and a yoke on the stator side. dynamic motor. 3. A patent in which the means for applying a load in the radial direction to the rotor (2) is a pressure spring provided between the shaft (1) that rotatably supports the rotor (2) and the inner side of the rotor (2). A swing motor for head access according to claim 1.