JPH07274470A - Manufacture of actuator disc device - Google Patents

Abstract

PURPOSE:To make this actuator excellent in dimensional precision by uniting and fixing an arm and a coil bobbin with a bearing as the center by the injection molding of thermoplastic resin. CONSTITUTION:For the bearing mounting hole 9a of an arm 2, one hand is opened rather largely so that a bearing 9 with rib can pass through it. The bearing 9 with rib is engaged freely in the bearing mounting hole 9a. Moreover, the bearing insertion piece 11 of a coil bobbin 10 holds the bearing 9 wit rib. In such a condition, the arm 2, the coil bobbin 10, and the bearing 9 with rib are assembled temporarily in a mold for injection molding, and by the injection molding of thermoplastic resin, the bearing 9, the arm 2, and the coil bobbin 10 are united and fixed. The positional precision of the arm or coil bobbin can be achieved with the bearing by fixing them integrally this way, this becomes one excellent in precision.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a swing type actuator for a magnetic disk device, particularly a fixed magnetic disk device, having a magnetic head mounted thereon.

[0002]

2. Description of the Related Art Conventionally, a swing type actuator used in a magnetic disk device has been shown in FIG. FIG. 1 is a perspective view showing a magnetic head positioning mechanism used in a conventional magnetic disk device. In the figure, 1 is a magnetic head positioning mechanism, 2 is an arm, 3 is a rotating shaft, 4 is a movable coil, 5 is a magnetic circuit, 6 is a support plate, and 7
Is a magnetic head, and 8 is a positioning pin.

In the figure, a magnetic head positioning mechanism 1
The arm 2 in FIG. 2 is for holding the magnetic head 7, and the rotating shaft 3 is the center of rotation of the arm 2 and is fixed by the support plate 6. The movable coil 4 is fixed to the arm 2, and the magnetic flux generated by the energization of the movable coil 4 passes through the magnetic circuit 5. Further, the positioning of the arm 2 is performed by the positioning pin 8.

Next, the operation of the conventional actuator shown in FIG. 1 will be described. When the coil 4 is fixed to the arm 2 and the coil 4 in the magnetic circuit 5 is energized, the generated magnetic flux passes through the magnetic circuit 5 and a driving force is generated according to Fleming's left-hand rule to hold the magnetic head 7. The reference numeral 2 makes a rotational movement around the rotation axis 3. Here, the rotary shaft 3 is supported by a support plate 6, and is press-fitted or adhered to a bearing (not shown).

Although the actuator in the conventional magnetic disk device is constructed as described above, naturally, the actuator is required to have high dimensional accuracy because it corresponds to a signal at a predetermined position on the magnetic disk. To be done.

For example, Japanese Patent Application Laid-Open No. 4-229062 discloses a technique in which a peripheral portion of a movable coil composed of an air-core coil is held by a holding member, an arm is also held, and integrally molded by injection molding.

According to this technique, due to its structure, an air core coil or an arm is installed at a predetermined position in an injection molding die during injection molding, and then a resin as a holding member is injected into the die to actuate the actuator. Will be molded.

However, the pressure of the resin injected into the mold is extremely high. Therefore, in such a method, the air-core coil is apt to change due to pressure, and the air-core coil and the arm are only temporarily fixed in the mold by a locking means such as an adhesive, which is high. Since the mutual positional relationship is likely to change due to the injection pressure, the actuator having the configuration described in the above publication does not always provide a product with good dimensional accuracy.

Therefore, it has been earnestly desired to develop a manufacturing method capable of obtaining an actuator with a small coil deformation and a high dimensional accuracy of the mutual positional relationship of the coil and the arm.

[0010]

DISCLOSURE OF THE INVENTION The present invention solves these problems of the prior art, reduces the weight of the arm, prevents the deformation of the coil, and has excellent dimensional accuracy and economical production. It is an object of the present invention to provide a method of manufacturing a disk capable of achieving the above, particularly an actuator of a magnetic disk device.

[0011]

[Means for Solving the Problems] In order to solve the above problems, the inventors of the present invention have earnestly studied and arrived at the present invention.

That is, the present invention has a head as a functional member, an arm supporting the head, and a movable coil that operates in a magnetic circuit, and the head is positioned by a swinging motion of the arm around a rotation axis. In the method for manufacturing an actuator for a disk device, a cylindrical columnar bearing made of metal is loosely fitted in a bearing mounting hole of the arm made of thermoplastic resin, and a coil wire is wound around a bobbin. The bearing is gripped by the bearing mounting piece of the coil bobbin, temporarily assembled in this state in a mold for injection molding, and the bearing is formed by injection molding of a thermoplastic resin,
A method for manufacturing an actuator for a disk device is characterized in that an arm and a coil bobbin are integrally fixed.

[0013]

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

FIG. 2 is a perspective view showing an example of the bearing 9. In the present invention, the bearing 9 is made of a metal cylindrical material. Examples of the metal used here include materials such as stainless steel from the viewpoint of thinness and high strength. In this way, by forming the bearing into a cylindrical body made of metal, the strength is improved and the reliability is extremely improved. It should be noted that FIG. 7A shows a case with a brim and FIG. 8B shows a case without a brim.

FIG. 3 is a perspective view of the arm 2 in which the mounting hole 9b of the bearing 9 is opened, and FIG. 4 is a perspective view of the coil bobbin. As shown in FIG. 3, the arm 2 includes, for example, 3
It is used by stacking sheets. An air-core coil or the like is used as the movable coil and is not particularly limited. However, as shown in FIG. 4, a coil bobbin in which a coil wire is wound around the bobbin 10 is preferably used. By using such a coil bobbin, the drawback that the coil is deformed by the injection pressure and the dimensional accuracy is reduced is eliminated. The bobbin 10 is provided with an insertion piece 11 which is formed integrally with or separately from the bobbin 10 so as to be inserted into the bearing 9.

In the present invention, this arm 2 and bobbin 1
0 is molded with a thermoplastic resin. The specific gravity of the thermoplastic resin is appropriately selected in consideration of the balance of the entire actuator, but the specific gravity of the thermoplastic resin is preferably 1.7 or less from the viewpoint of weight reduction.

Particularly, the thermoplastic resin forming the arm 2 has a linear expansion coefficient of 3 × 10 ⁻⁵ / ° C. or less and an elastic modulus of 8 × 10 ^2.
It is preferable that the weight loss is not less than kgf / mm ² and the loss factor is not less than 0.01. As a result, the weight of the arm can be reduced, the dimensional stability is excellent, and the rigidity sufficient for supporting the magnetic head and the excellent damping characteristic against vibration can be obtained. The product thickness of this arm can be thinned for weight reduction according to the elastic modulus of the resin.

As the thermoplastic resin used here,
For example, thermotropic liquid crystal polymer; polyamide resin such as nylon; polyacetal resin; polycarbonate resin; modified polyphenylene ether; polyester resin such as polyethylene phthalate and polybutylene phthalate; polyphenylene sulfide resin; polysulfone resin; polyether Examples include polyetherketone-based resins such as etherketone; wholly aromatic polyester-based resins such as polyarylate; ABS-based resins; polyolefin-based resins such as reinforced polypropylene; and thermotropic liquid crystal polymers are particularly preferably used.

The thermotropic liquid crystal polymer as used herein is a meltable polymer which is a thermoplastic which exhibits optical anisotropy when melted. As described above, the polymer exhibiting optical anisotropy when melted has a property that the polymer molecular chains have a regular parallel arrangement in the melted state. The properties of the optically anisotropic molten phase can be confirmed by a usual polarization inspection method using a crossed polarizer.

For example, liquid crystalline polyester, liquid crystalline polyester imide and the like, specifically, (all) aromatic polyester, polyester amide, polyester carbonate and the like can be mentioned. The thermotropic liquid crystal polyester resin is included in the category of polyester as long as it has a plurality of ester bonds in the molecule. More preferred polyester is
It is an aromatic polyester.

In the thermotropic liquid crystal polyester resin used in the present invention, a part of one polymer chain is composed of a polymer segment forming an anisotropic melt phase, and the remaining part is an anisotropic melt phase. Also included are polymers composed of segments of polymer that do not form. Also,
A composite of a plurality of thermotropic liquid crystal polyester resins is also included.

Typical examples of the monomer constituting the thermotropic liquid crystal polyester resin include (a) at least one aromatic dicarboxylic acid, (b) at least one aromatic hydroxycarboxylic acid compound, and (c) aromatic. At least one kind of diol compound, at least one kind of (d) (d ₁ ) aromatic dithiol, (d ₂ ) aromatic thiophenol, (d ₃ ) aromatic thiol carboxylic acid compound,
(E) At least one kind of aromatic hydroxyamine, aromatic diamine compound, etc. may be mentioned.

Although these may be configured independently,
Many are (a) and (c), (a) and (d), (a),
(B) and (c), (a), (b) and (e), or (a), (b), (c) and (e) and the like.

As the above-mentioned (a) aromatic dicarboxylic acid type compound, terephthalic acid, 4,4'-diphenyldicarboxylic acid, 4,4'-triphenyldicarboxylic acid, 2,6-
Naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, diphenylether-4,4'-dicarboxylic acid, diphenoxyethane-4,4'-dicarboxylic acid, diphenoxybutane-4,
4'-dicarboxylic acid, diphenylethane-4,4'-dicarboxylic acid, isophthalic acid, diphenylether-3,
3'-dicarboxylic acid, diphenoxyethane-3,3'-
Aromatic dicarboxylic acids such as dicarboxylic acid, diphenylethane-3,3'-dicarboxylic acid, 1,6-naphthalenedicarboxylic acid or chloroterephthalic acid, dichloroterephthalic acid, bromoterephthalic acid, methylterephthalic acid,
Examples thereof include alkyl, alkoxy or halogen substitution products of the above aromatic dicarboxylic acids such as dimethyl terephthalic acid, ethyl terephthalic acid, methoxy terephthalic acid and ethoxy terephthalic acid.

(B) Aromatic hydroxycarboxylic acid compounds include aromatic hydroxy such as 4-hydroxybenzoic acid, 3-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid and 6-hydroxy-1-naphthoic acid. Carboxylic acid or 3-methyl-4-hydroxybenzoic acid, 3,5
-Dimethyl-4-hydroxybenzoic acid, 2,6-dimethyl-4-hydroxybenzoic acid, 3-methoxy-4-hydroxybenzoic acid, 3,5-dimethoxy-4-hydroxybenzoic acid, 6-hydroxy-5-methyl -2-naphthoic acid, 6-hydroxy-5-methoxy-2-naphthoic acid,
2-chloro-4-hydroxybenzoic acid, 3-chloro-4
-Hydroxybenzoic acid, 2,3-dichloro-4-hydroxybenzoic acid, 3,5-dichloro-4-hydroxybenzoic acid, 2,5-dichloro-4-hydroxybenzoic acid, 3
-Bromo-4-hydroxybenzoic acid, 6-hydroxy-
Alkyl, alkoxy or halogen substitution of aromatic hydroxycarboxylic acid such as 5-chloro-2-naphthoic acid, 6-hydroxy-7-chloro-2-naphthoic acid, 6-hydroxy-5,7-dichloro-2-naphthoic acid The body.

As the aromatic diol (c), 4,4 '
-Dihydroxydiphenyl, 3,3'-dihydroxydiphenyl, 4,4'-dihydroxytriphenyl, hydroquinone, resorcin, 2,6-naphthalenediol, 4,4'-dihydroxydiphenyl ether, bis (4-hydroxyphenoxy) ethane, 3 , 3'-Dihydroxydiphenyl ether, 1,6-naphthalenediole, 2,2-bis (4-hydroxyphenyl) propane, bis (4-hydroxyphenyl) methane and other aromatic diols or chlorohydroquinone Alkyl, alkoxy or halogen substitution products of aromatic diols such as methyl hydroquinone, t-butyl hydroquinone, phenyl hydroquinone, methoxy hydroquinone, phenoxy hydroquinone, 4-chlororesorcinol and 4-methylresorcinol. That.

Examples of the aromatic dithiol (d ₁ ) include benzene-1,4-dithiol, benzene-1,3-dithiol, 2,6-naphthalene-dithiol and 2,7-naphthalene-dithio. -Ru and the like.

As the (d ₂ ) aromatic thiophenol,
4-mercaptophenol, 3-mercaptophenol
And 6-mercaptophenol and the like. Examples of (d ₃ ) aromatic thiol carboxylic acid include 4-mercaptobenzoic acid, 3-mercaptobenzoic acid, 6-mercapto-2-naphthoic acid and 7-mercapto-2-naphthoic acid.

(E) Aromatic hydroxyamine and aromatic diamine compounds include 4-aminophenol and N-
Methyl-4-aminophenol, 1,4-phenylenediamine, N-methyl-1,4-phenylenediamine,
N, N'-dimethyl-1,4-phenylenediamine, 3
-Aminophenol, 3-methyl-4-aminophen-
2-chloro-4-aminophenol, 4-amino-
1-naphthol, 4-amino-4'-hydroxydiphenyl, 4-amino-4'-hydroxydiphenylether, 4-amino-4'-hydroxydiphenylmethane,
4-amino-4'-hydroxydiphenyl sulfide,
4,4'-diaminophenyl sulfide (thiodianiline), 4,4 'diaminodiphenyl sulfone, 2,5-
Diaminotoluene, 4,4'-ethylenedianiline,
4,4'-diaminodiphenoxyethane, 4,4'-diaminodiphenylmethane (methylenedianiline), 4,
4'-diaminodiphenyl ether (oxydianiline) and the like can be mentioned.

The thermotropic liquid crystal polyester resin used in the present invention can be produced from the above-mentioned monomers by various ester forming methods such as a melt acidolysis method and a slurry polymerization method.

As for the molecular weight, that of the thermotropic liquid crystal polyester resin suitable for use in the present invention is about 2
000-200000, preferably about 4000-100
It is 000. The molecular weight can be measured, for example, by measuring the end groups of a compressed film by infrared spectroscopy. Alternatively, GPC, which is a general measurement method involving solution formation, can be used.

Among the thermotropic liquid crystal polyester resins obtained from these monomers, aromatic polyesters which are (co) polymers containing the monomer unit represented by the following general formula (1) as an essential component are preferable. The monomer unit preferably contains about 30 mol% or more. More preferably, it contains about 50 mol% or more.

[0033]

[Chemical 1]

A particularly preferred aromatic polyester of the present invention is a copolyester represented by the following formula (2) having repeating units each having a structure derived from three compounds of p-hydroxybenzoic acid, phthalic acid and biphenol. is there. The repeating unit of the structure derived from the biphenol of the copolyester represented by the following formula (2) is
It may also be a copolyester in which some or all of it is substituted with repeating units derived from dihydroxybenzene. It is a copolyester represented by the following formula (3) having repeating units each having a structure derived from two compounds of p-hydroxybenzoic acid and hydroxynaphthalenecarboxylic acid.

[0035]

[Chemical 2]

[0036]

[Chemical 3]

The thermotropic liquid crystal polyester resin used in the present invention may be used alone, or two or more kinds thereof may be mixed and used.

Two or more kinds of these synthetic resins can be used or a mixture of other polymers such as rubber can be used.
At this time, it is preferable to use a compatibilizing agent in order to improve the compatibility of each component. Further, these synthetic resins can be used after being chemically modified.

Various additives can be added to the above synthetic resin depending on the purpose. This includes inorganic and organic fillers (glass fiber, carbon fiber, talc, mica, calcium carbonate, clay, calcium sulfate, magnesium hydroxide,
Silica, alumina, barium sulfate, titanium oxide, zinc oxide, iron oxide, ferrite, molybdenum sulfide, graphite, wood powder, various whiskers, metal powder, glassy carbon, etc., various stabilizers (antioxidant, ultraviolet absorber, Light stabilizers, metal deactivators, etc.), pigments, dyes, plasticizers, oils, lubricants, nucleating agents, antistatic agents, flame retardants and the like.

As the thermoplastic resin forming the arm of the present invention, the linear expansion coefficient of 3 × 10 ^-5 / ° C. can be obtained by appropriately selecting the above-mentioned resin or by appropriately selecting the inorganic filler. Hereinafter, it is possible to impart physical properties having an elastic modulus of 8 × 10 ² kgf / mm ² and a loss coefficient of 0.01 or more.

FIGS. 5 (a) and 5 (b) are a plan view and a side view showing a state in which the arm 2 and the coil bobbin 10 are set on the flanged bearing 9 shown in FIG. 2 (a). One of the bearing mounting holes 9a of the arm 2 is slightly larger so that the bearing 9 with a flange can pass therethrough.
The flanged bearing 9 is loosely fitted in the bearing mounting hole 9a. In addition, the bearing mounting piece 1 of the coil bobbin 10
The bearing 9 with a brim is gripped by 1. In this state, the arm 2, the coil bobbin 10 and the bearing 9 with a brim
6 is temporarily assembled in an injection molding die (not shown),
7 to 7, the bearing 9, the arm 2 and the coil bobbin 10 are integrally fixed by injection molding with a thermoplastic resin. By fixing the arms and the coil bobbin integrally as described above, the positional accuracy of the arm and the coil bobbin can be obtained by the bearing, which is also excellent in accuracy. That is, when the bearing 9 is arranged at a predetermined position of the mold, and is integrally fixed by the thermoplastic resin 12 by injection molding, the thermoplastic resin also enters into the void portion of the bearing mounting hole 9a, and the arm 2 or the arm 2 with the bearing 9 as the center. The coil bobbin 10 is accurately integrated.

FIGS. 6 (a) and 6 (b) are a plan view and a side view showing an actuator used in a magnetic disk device according to an embodiment of the present invention. As shown in the side view of FIG. 7, the actuator may have a plurality of arms 2 shown in FIG. 6 to 7, the arm and the coil bobbin are fixed so that the bobbin mounting piece is wrapped with a thermoplastic resin.

[0043]

As is apparent from the above description, the present invention has the following effects. Since the arm and coil bobbin centering on the bearing are integrally fixed by injection molding with a thermoplastic resin,
The dimensional accuracy is extremely excellent because the position accuracy of the arm and coil can be obtained by the bearing. Since the arm is formed of a thermoplastic resin having specific physical properties, the arm can be made smaller and lighter, so that the magnetic circuit that drives the movable portion can be made smaller. Moreover, it has excellent dimensional stability, and has sufficient rigidity for supporting the magnetic head and excellent damping characteristics against vibration. Since the bearing is a cylindrical body made of metal, the strength is improved and the reliability is very high. Since the moving coil uses a coil bobbin, dimensional accuracy does not deteriorate due to deformation of the moving coil during molding. Therefore, the actuator obtained by the present invention is
It is preferably used for magnetic disk devices.

[Brief description of drawings]

FIG. 1 is a perspective view of a swing type actuator used in a conventional magnetic disk device.

FIG. 2 is a perspective view showing an example of a bearing used in the present invention.

FIG. 3 is a perspective view showing an example of an arm used in the present invention.

FIG. 4 is a perspective view showing an example of a coil bobbin used in the present invention.

5A and 5B are a plan view and a side view showing a state in which an arm and a coil bobbin are set on a bearing.

6A and 6B are a plan view and a side view showing an actuator used in a magnetic disk device that is an embodiment of the manufacturing method of the present invention.

FIG. 7 is a side view showing an actuator used in a magnetic disk device which is another embodiment of the manufacturing method of the present invention.

[Explanation of symbols]

1: magnetic head positioning mechanism, 2: arm, 3: rotating shaft, 4: movable coil, 5: magnetic circuit, 6: support plate, 7:
Magnetic head, 8: Positioning pin, 9: Bearing, 9a, 9
b: bearing mounting hole, 10: bobbin, 11: bearing insertion piece, 12: fixing thermoplastic resin.

Claims (5)

[Claims] 1. A disk device having a head as a functional member, an arm supporting the head and a movable coil operating in a magnetic circuit, and positioning the head by swinging motion of the arm around a rotation axis. In the method for manufacturing an actuator, the cylindrical bobbin bearing, which is made of a thermoplastic resin, is loosely fitted in the bearing mounting hole of the arm, and the coil wire is wound around the bobbin. A disk device characterized in that the bearing is gripped by a mounting piece, temporarily assembled in an injection molding die in this state, and the bearing, arm and coil bobbin are integrally fixed by injection molding of a thermoplastic resin. Actuator manufacturing method. 2. The method for manufacturing an actuator according to claim 1, wherein the bobbin is formed of a thermoplastic resin. 3. The thermoplastic resin forming the arm,
Linear expansion coefficient 3 × 10 ^-5 / ° C or less, elastic modulus 8 × 10 ² kg
The method for manufacturing an actuator according to claim 1 or 2, wherein f / mm ² or more and a loss coefficient are 0.01 or more. 4. The method for manufacturing an actuator according to claim 1, 2 or 3, wherein a plurality of the arms are laminated. 5. The method for manufacturing an actuator according to claim 1, wherein the thermoplastic resin forming the arm is a thermotropic liquid crystal polymer.