JP2001155447A - Actuator for hard disk drive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve accuracy of a bearing part of a support part which is supported by a pivot axis and, at the same time, to reduce the product cost. SOLUTION: In this actuator for a hard disk drive, the support part 2 which is freely rotatably mounted to the pivot axis disposed on the HDD housing side, a swing arm 3 which is extended in one direction from the support part 2 and equipped with a magnetic head on the tip thereof and a coil holding part 4 which holds a voice coil 5 for a drive are integrally formed by resin molding, a through-hole 2a is formed on the support part 2 and at least three protrusions 2b for the bearing which protrudes from the inner surface of the through-hole toward the rotation center of the actuator are formed. By means of the respective tips of the protrusions 2b for the bearing, the support part 2 is positioned with respect to the pivot axis and the rotation accuracy of the actuator 1 is improved thereby.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary actuator used in a hard disk drive having a built-in magnetic disk.

[0002]

2. Description of the Related Art Hard disk drives (HDDs)
It is mainly used as an auxiliary storage device for personal computers, and recently, a product having a capacity of 20 GB class has appeared. In addition, the speed of writing / reading has also been rapidly increasing, and with this, magnetic disk rotation speeds of 3600 rpm to 7200 rpm and ultra-high speed products of 10,000 rpm have been developed. Has appeared.

As shown in FIG. 9, a hard disk drive has a magnetic disk 100 having a magnetic layer formed on the surface.
And a magnetic head 102 for writing and reading data to and from the magnetic disk 100, and an actuator 101 for displacing the magnetic head 102. The actuator 101 is rotatably supported by a pivot shaft 103 provided near the magnetic disk 100, and has a voice coil 115 provided on the opposite side of the magnetic head 102.
And a linear motor 110 composed of a permanent magnet 104 provided on the HDD housing side. The rotation causes the swing arm 113 to swing, and the magnetic head 102 at the tip moves to a predetermined track on the magnetic disk 100. It has a structure. Generally, two to ten magnetic disks are built in one hard disk drive.

Conventionally, an actuator used for a hard disk drive is made of, for example, aluminum in a projected shape of the actuator (an outer shape in a plan view of FIG. 9).
After extrusion molding, the molded product is cut into blocks of a predetermined thickness, and then each block is processed into a shape as shown in FIG. 10 by cutting or the like, and burrs at the corners of the processed product are hand-finished. And then subjecting the product surface to a pretreatment / electroless plating of Ni.

[0005]

In the case of a hard disk drive, since the rotational accuracy of the actuator greatly affects the writing / reading accuracy of the hard disk, the accuracy of the bearing portion of the support portion (bearing hole 10) is high.
2a) is required to have high precision. However, in the conventional actuator, after performing drilling (bearing hole processing) on a semi-finished product of aluminum, high precision cylindrical grinding is performed to achieve roundness. It had to be secured, and the processing required a lot of time and cost.

According to the conventional actuator shown in FIGS. 9 and 10, a bearing hole (cylindrical hole) 102 of the support portion 102 is formed in order to reduce sliding resistance with the pivot shaft.
A bearing sleeve 120 (for example, a resin or metal sleeve or bearing) is fitted into the bearing a, so that the bearing sleeve 120 is required extra and high dimensional accuracy is required for the bearing sleeve and the like. Therefore, there is also a problem that the component cost is high.

The present invention has been made in view of such circumstances, and it is an object of the present invention to provide a hard disk drive actuator in which the accuracy of a bearing portion of a support portion supported by a pivot shaft is high and the product cost is low. .

[0008]

An actuator of the present invention is a rotary actuator used for a hard disk drive having a built-in magnetic disk, and is rotatably mounted on a pivot shaft provided near the magnetic disk. It consists of a support part, a swing arm that extends in one direction from the support part and has a magnetic head attached to the tip, and a coil holding part that holds a driving voice coil. The support part, the swing arm, and the coil holding part are formed of resin. And at least three bearing projections are formed in the support portion, the through-holes are formed in the support portion, and project from the inner surface of the through-hole toward the rotation center of the actuator. When each tip of the projection abuts on the outer peripheral surface of the pivot shaft when mounted on the pivot shaft, the support part pivots. It characterized by being configured to be positioned against.

As described above, by positioning the support portion of the actuator with at least three bearing projections, the sliding resistance with respect to the pivot shaft can be made extremely small, and the rotation property of the actuator is improved. Further, a bearing sleeve or the like conventionally used becomes unnecessary, and the number of parts (product cost) can be reduced.

[0010]

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

FIG. 1 is a perspective view of an embodiment of the present invention.
FIG. 2 is a plan view (A) and a side view (B) of the embodiment. 3 and 4 are a cross-sectional view taken along line CC and a cross-sectional view taken along line DD of FIG. 2, respectively.

The actuator 1 of the present embodiment comprises a support portion 2 rotatably mounted on a pivot shaft 103 (see FIG. 9) provided in the vicinity of a magnetic disk, and four support members 2 extending in one direction from the support portion 2. 3 and a coil holding portion 4 projecting from the support portion 2 on the opposite side to the swing arm 3. The support portion 2, the swing arms 3... 3 and the coil holding portion 4 are made of resin. It is integrally formed by injection molding.

The swing arm 3 is formed in such a shape that its thickness is reduced from the center in the width direction toward both ends, and that the thickness is reduced from the support portion 2 toward the tip of the arm 3. At the tip of the swing arm 3, a mounting hole 3a for fixing a gimbal (not shown) of the magnetic head is formed.

The coil holding section 4 is a C-shaped member having an open end, and the voice coil 5 is attached inside. The outer peripheral surface of the coil holding part 4 is formed in a round shape. On the inside (coil mounting surface) of the coil holding portion 4,
As shown in FIG. 3, a concave portion 4a extending at a constant width and depth along the inner peripheral edge of the coil holding portion 4 is formed, and further, at the center of the concave portion 4a, a constant height along the inner peripheral edge. , A convex portion 4b is integrally formed. Recess 4
The width W of a is processed to the same size as the thickness of the voice coil 5 attached to the coil holding unit 4 or a size smaller by a predetermined amount. On the outer peripheral surface of the voice coil 5, a fitting concave portion 5b having a shape and a size corresponding to the convex portion 4b of the coil holding portion 4 is provided. The fitting recess 5b can be easily realized by devising a winding method of the coil.

The dimensions of each part of the actuator 1 including the concave part 4a and the convex part 4b of the coil holding part 4 are processed based on the precision required in a hard disk drive.

In this embodiment, as shown in FIGS. 1, 2, 5, and 6, the support portion 2 is provided with a cylindrical through hole 2a centered on the rotation center of the actuator 1. Three projections 2b are formed integrally with each other and project from the inner surface of the cylinder toward the center of the cylinder by a predetermined amount. The three bearing projections 2b... 2b are arranged rotationally symmetrically, and each tip of the bearing projections 2b.

The amount of protrusion of the bearing projections 2b... 2b from the inner surface of the cylinder is determined in such a manner that the ends of the bearing projections 2b. The support portion 2 is positioned with respect to the pivot shaft 103 by the bearing projections 2b... 2b, and the support portion 2 is rotatably supported by the pivot shaft 103. .

When the actuator 1 is a resin molded product, it is easy to machine the cylindrical bearing hole 102a as shown in FIG. It is difficult to get high roundness for However, the bearing structure of the supporting portion is not shown in FIG.
2b, that is, a structure in which the pivot shaft 103 is received at the tips of the three bearing projections 2b,... 2b projecting from the inner surface of the through hole 2a, the dimensional accuracy of the tip of the bearing projection 2b is reduced , It is possible to easily increase the accuracy required for a hard disk drive.

In the actuator 1 having the structure shown in FIGS. 1 to 3, as shown in FIGS. 4 and 2, the shape of the swing arm 3 is reduced in thickness from the center in the width direction to both ends. Since the shape is such that the wall thickness is reduced from the support portion 2 toward the tip of the arm 3 and the outer peripheral surface of the coil holding portion 4 is rounded, air resistance during rotation of the actuator 1 can be reduced. it can.

Further, by forming the swing arm 3 as described above, the formability of the swing arm 3 can be improved. That is, when the actuator 1 including the support portion 2, the swing arm 3, and the coil holding portion 4 is integrally molded (injection-molded), the flow of the molten resin in the mold from the support portion 2, which is a thick portion, is increased. Swing arm 3
In general, in such a resin flow molding, the shape of the swing arm 3 is set such that the thickness of the swing arm 3 increases from the root (the support portion 2 side) toward the tip. If the thickness is reduced, the molding fluidity becomes better and the moldability is improved as compared with the case where the wall thickness is constant. As a result, the dimensional accuracy of the swing arm 3 can be improved. Furthermore, if the thickness is reduced from the center in the width direction of the swing arm 3 toward both sides, the molding fluidity in the width direction of the swing arm 3 is improved, and the dimensional accuracy is further improved.

Actuator 1 having the structure shown in FIGS.
According to the first embodiment, the voice coil 5 is
Then, the voice coil 5 can be accurately positioned with respect to the actuator 1 by fitting the voice coil 5 with the fitting concave portion 5b fitted to the convex portion 4b in the concave portion 4a. Further, since the voice coil 5 is sandwiched in the concave portion 4a of the coil holding portion 4 and the convex portion 4b in the concave portion 4a is fitted in the fitting concave portion 5b of the voice coil 5, the fitting of these members is performed. In some cases, there is an advantage that the fixing force of the voice coil 5 is increased and the voice coil 5 can be held more reliably.

In the above embodiment, the number of the bearing projections provided on the support portion 2 is three, but the number may be four or more. However, considering the rotation stability of the actuator 1, the number of the bearing projections is preferably three.

Further, the shape of the tip of the bearing projection is preferably a round shape as shown in FIG. 5 in consideration of reducing the sliding resistance. For example, as shown in FIG.
The shape of the tip of the bearing projection 12b may be a flat surface 12c, or, as shown in FIG.
May be a concave surface 22c having a shape conforming to the outer peripheral surface of the pivot shaft 103.

Further, in the above embodiment, the present invention is applied to an actuator in which the swing arm is shaped so that the thickness in the width direction is reduced and the thickness is reduced from the root to the tip. Is shown, but
The present invention is not limited to this, and can be applied to an actuator having a swing arm 113 having the shape shown in FIG. 10, that is, a swing arm having a constant thickness in the width direction and the longitudinal direction.

Here, it has been confirmed at present that a product excellent in dimensional accuracy and reliability can be obtained even when the actuator is an integrally molded product of resin as in the above embodiment. By making the actuator a resin molded product, the product cost can be significantly reduced. Moreover, since the weight of the actuator can be reduced, the driving force of the linear motor can be reduced, and the controllability of the position control of the magnetic head can be further improved.

As described above, in the conventional actuator, as described above, for example, after extrusion molding of aluminum, the molded product is cut into blocks having a predetermined thickness, and then each block is formed by cutting or the like as shown in FIG. It is manufactured in the process of processing into a shape, removing the burrs and the like at the corners of the processed product by hand finishing, and then preparing the surface of the product and performing electroless plating of Ni, so that the number of manufacturing steps is large, and However, there has been a problem that the material yield is very poor, but these problems can be solved all at once by using a resin molded product for the actuator.

[0027]

As described above, according to the actuator of the present invention, the supporting portion, the swing arm and the coil holding portion rotatably mounted on the pivot shaft disposed near the magnetic disk are integrally formed of resin. Along with the product, a through hole is formed in the support portion along the center of rotation, and projects from the inner surface of the through hole toward the center of rotation.
Since at least three bearing projections are formed, the sliding resistance with respect to the pivot shaft can be made extremely small, and the rotation of the actuator can be enhanced. In addition, a bearing sleeve or the like conventionally used becomes unnecessary, and the number of parts (product cost) can be reduced.
In addition, since the actuator is formed as an integrally molded product of resin, the product cost is reduced as compared with, for example, an actuator made of aluminum.

[Brief description of the drawings]

FIG. 1 is a perspective view of an embodiment of the present invention.

FIG. 2 is a plan view (A) and a side view (B) of the embodiment of the present invention.

FIG. 3 is a sectional view taken along line CC of FIG. 2;

FIG. 4 is a sectional view taken along line DD of FIG. 2;

FIG. 5 is an enlarged view of a main part of the embodiment of the present invention.

FIG. 6 is a sectional view taken along the line EE of FIG. 5;

FIG. 7 is a view showing a modified example of a bearing projection.

FIG. 8 is a diagram showing another modified example of the bearing projection.

FIG. 9 is a diagram schematically showing a main part structure of a hard disk drive.

10 is a perspective view of an actuator (conventional product) used for the hard disk drive of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Actuator 2 Support part 2a Through hole 2b Bearing projection 3 Swing arm 3a Mounting hole (for magnetic head mounting) 4 Coil holding part 4a Depression 4b Convex part 5 Voice coil 5b Fitting concave

Continuation of the front page (71) Applicant 599166219 Yamada Precision Co., Ltd. 11485-4 Yuki, Yuki-shi, Ibaraki (71) Applicant 000206901 Otsuka Chemical Co., Ltd. 3-27, Odori, Chuo-ku, Osaka-shi, Osaka (72) Invention Person Noriaki Ogawa 1820-6 Ueno, Kumagaya-shi, Saitama (72) Inventor Hiroshi New Year 2-104, Higashi-Nara, Ibaraki-shi, Osaka F-term (reference) 3J105 AA02 AB49 AB50 AC10 BB26 BB31 BC02 5D068 AA01 BB02 CC12 EE18 EE19 GG07

Claims (1)

[Claims] 1. A rotary actuator used in a hard disk drive having a built-in magnetic disk, comprising: a support portion rotatably mounted on a pivot shaft provided near the magnetic disk; The swing arm includes a swing arm on which a magnetic head is attached at the extended end, and a coil holding portion for holding a voice coil for driving. The support portion, the swing arm and the coil holding portion are integrally formed by resin molding, and the support portion is formed. And at least three bearing projections projecting from the inner surface of the through hole toward the rotation center of the actuator, and each tip of the bearing projections is connected to the pivot shaft. In the mounted state, the support portion is configured to abut on the outer peripheral surface of the pivot shaft so that the support portion is positioned with respect to the pivot shaft. An actuator for a hard disk drive.