JPH08336854A - Actuator of disk device, its arm, and its manufacture - Google Patents

Abstract

PURPOSE: To improve dimensional precision while a manufacturing cost of a resin-made arm is reduced by a method wherein a resin-made connecting part to be cut or removed is provided at least at one position in a plurality of arm parts. CONSTITUTION: Molten resin is injected via a sprue 19 of a mold and each runner 20 to make the resin flow to a shaft hole 6 part from each gate 20', the resin is made to go round on both sides of the shaft hole 6, and reach a weld and line part. At that time a resin molecule is oriented in the flow direction. After the resin is solidified, the mold is released by releasing the mold part from the resin, and an intermediate product of an arm is obtained. The intermediate product is in a state wherein it is connected to the sprue 19 and the runner 20, and the connected state is kept until the resin is thoroughly solidified. Then, when the resin is thoroughly solidified, the arm can be obtained by cutting off a connection part consisting of each sprue 19 and each runner 20.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a swing type actuator used in a fixed magnetic disk drive or the like for driving a magnetic head along an arcuate path and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, a swing type actuator is
As shown in FIG. 4, it is usually provided with a multilayered arm 2 having a plurality of arm portions 11, and a coil portion 12 having a coil for swinging the arm 2 around the shaft hole 6. A functional member such as a magnetic head called a head suspension is attached to the tip of each arm 11.

Here, the movable coil is a coil formed by winding a conductive wire having an insulating film, and when an electric current is applied, it is based on Fleming's left-hand rule, that is, a magnetic circuit using a permanent magnet (neither is shown). The driving force acts on the coil due to the action of), and the arm portion 2 is swung about the shaft hole 6.

Nowadays, in order to further improve the positioning accuracy and positioning speed of the actuator, there is a demand for a lighter arm because of the recent demands for increasing the recording density and shortening the access speed. Therefore, it has been proposed that the arm be made of resin. (Japanese Patent Laid-Open No. 4-2290
62 "Oscillating actuator") In such a proposal, the arm is formed for each arm portion, and these arm portions are laminated to form an arm having a multilayer structure.

In particular, in recent years, the increase in recording capacity of fixed magnetic disks and other fixed disk recording devices has been dealt with by increasing the number of disks. Since each arm portion of the actuator corresponds to each disk on a one-to-one basis, as a result, the number of arm portions must be increased. Many metal arms and the like have three or more arm portions, and some have 2 to 20 arms.

[0006]

However, conventionally,
Even if there is a proposal for an actuator made of resin arm, it is necessary to separate each arm part individually,
Since the arms are individually formed and then the arms are fixed to each other by an appropriate method, it is difficult to integrally and simultaneously form the arms having a plurality of arms. That is, it is necessary that the respective arm portions are exactly parallel to each other, but it is difficult to make this parallel. More specifically, in the case of injection molding with a thermoplastic resin, the molded product is taken out from the mold after the resin is once solidified, but since the molten resin is not sufficiently solidified, the arm part warps after being taken out. . However, it is uneconomical to leave it in the mold until it is sufficiently solidified, because the molding time becomes long.

Further, the sprue, runner and the like play a role of connecting the respective arm portions. Due to the existence of these connecting parts,
The relative positional displacement of each arm portion is reduced. For example,
Little deformation even with the protruding pin for demolding. Therefore, the structure of the connecting portion such as the sprue and the runner can be set to have such a length, width, thickness and the like that deformation due to the protruding pin or the like is reduced due to its reinforcing effect. However, it is preferable in terms of manufacturing that the thickness of the connecting portion is the same as the thickness of each arm portion of the arm.

An object of the present invention is to provide a resin arm having a low manufacturing cost and excellent dimensional accuracy, and a manufacturing method thereof, in view of the above problems of the prior art.

[0009]

In order to achieve the above-mentioned object, according to the present invention, each arm portion is not necessary as a product molded at the same time when these arm portions and the arm including them are simultaneously injection-molded. And is connected by a resin portion to be removed or cut.

Further, the unnecessary resin portion is a resin portion existing on the injection path of the resin at the time of injection molding.

Further, the resin portion is characterized by connecting the vicinity of the tip of each arm portion.

In addition, an intermediate product of the arms is used, in which each arm portion is connected by a resin portion which is not required as a product to be molded at the same time when these arm portions and the arm including them are simultaneously injection-molded. Process by injection molding and take out from the mold, fully solidify the intermediate product taken out from the mold with the unnecessary resin part connected to each arm, and the fully solidified intermediate product And a step of separating the resin portion.

Further, it is provided with an arm obtained by separating the unnecessary resin portion from the intermediate product, and a coil fixed to this arm for giving a driving force for swinging this arm to this arm. It is characterized by

Further, an intermediate product of the arms, in which each arm portion is connected by a resin portion which is unnecessary as a product simultaneously molded when these arm portions and the arm including them are simultaneously injection-molded, is used in a mold. With the coil for swinging the arm set to, the step of molding by injection molding using resin and taking out from the mold, and the intermediate product taken out of the mold, unnecessary resin parts were connected to each arm The present invention is characterized by including a step of sufficiently breaking the raw material and a step of separating an unnecessary resin portion from the fully solidified intermediate product.

The thermoplastic resin used here has a higher rigidity as an actuator and is less likely to be deformed, and therefore has a bending elastic modulus of 8 × 10 ² kgf / mm ² (ASTM).
So-called engineering plastics (according to D790) or above is required. For example, polyamide resins such as nylon; polyacetal resins; polycarbonate resins; modified polyphenylene ethers; polyester resins such as polyethylene phthalate and polybutylene phthalate; polyphenylene sulfide resins; polysulfone resins; polyether ether ketone and other poly resins. Examples thereof include ether ketone resins; wholly aromatic polyester resins such as polyarylate; ABS resins; polyolefin resins such as reinforced polypropylene; thermotropic liquid crystal polymers.

The thermotropic liquid crystal polymer used as a preferred thermoplastic resin in the present invention is a resin which exhibits optical anisotropy in a molten state and is a thermoplastic meltable polymer. Such a polymer exhibiting optical anisotropy when melted has the property that the polymer molecular chains take 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. A polymer that does not exhibit general melt anisotropy becomes isotropic in the molten state, but when it exhibits anisotropy in the melting process, it changes from a solid phase to an isotropic phase through an anisotropic liquid crystal phase.

Mechanical anisotropy can also be confirmed. That is, it can be confirmed by the fact that peeling and fibrillation of the surface of the molded product become remarkable when injection molding is performed, and the difference in physical properties between the resin flow direction and the direction perpendicular to the direction is large.

The resin exhibiting optical anisotropy in the molten state is generally known as a thermotropic liquid crystal polymer. This thermotropic liquid crystal polymer is generally elongated, flat, and made from such monomers that have multiple chain extension bonds that are either rigid or co-axial or parallel along the long chain of the molecule. .

Polymers exhibiting optical anisotropy when melted are
It exhibits the property that the polymer molecular chains adopt a regular parallel arrangement in the molten state. The properties of the optically anisotropic molten phase can be confirmed by a usual polarization inspection method using a crossed polarizer.

Preferred as the thermotropic liquid crystal polymer is thermotropic liquid crystal polyester, for example, liquid crystalline polyester, liquid crystalline polyester imide, etc., specifically (all) aromatic polyester, polyester amide, polyester carbonate, etc. Is mentioned. It is included in the category of polyester as long as it contains a plurality of bonds to be discarded in the molecule. A more preferred polyester is an aromatic polyester.

In the thermotropic liquid crystal polyester used in the present invention, a part of one polymer chain is composed of polymer segments forming an anisotropic melt phase, and the remaining part does not form an anisotropic melt phase. Also included are polymers composed of polymer segments. Further, it also includes a composite of a plurality of thermotropic liquid crystal polymers.

Typical examples of the monomer constituting the thermotropic liquid crystal polyester include (a) at least one kind of aromatic dicarboxylic acid, (b) at least one kind of aromatic hydroxycarboxylic acid compound, and (c) aromatic diol. At least one type of compound, (d) (d ₁ ) aromatic dithiol, (d ₂ ) aromatic thiophenol, (d ₃ ) at least one type of aromatic thiolcarboxylic acid compound, (e) aromatic hydroxyamine, At least one kind of aromatic diamine-based compound may, for example, 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-
Naphterene dicarboxylic acid, 1,4-naphthalene dicarboxylic acid, 2,7-naphthalene dicarboxylic acid, diphenyl ether-4,4'-dicarboxylic acid, diphenoxyethane-4,4'-dicarboxylic acid, diphenoxybutane-4,
4'-dicarboxylic acid, diphenylethane-4,4'-dicarboxylic acid, isophthalic acid, diphenyl ether-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-chlororesorcin, 4-methylresorcin and the like. 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 acids include 4-mercaptobenzoic acid, 3-mercaptobenzoic acid, 6-mercapto-2-naphthoic acid and 7-mercapto-2-naphthoic acid.

(E) As aromatic hydroxyamine and aromatic diamine compounds, 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 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 suitable for use in the present invention is about 200.
0-200000, preferably about 4000-10000
0. The molecular weight can be measured, for example, by measuring the end groups of a compressed film by infrared spectroscopy. G, which is a general measurement method that involves solution formation
You can also use a PC.

Among the thermotropic liquid crystal polymers 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 50 mol% or more.

[0034]

Embedded image A particularly preferred aromatic polyester of the present invention is a polyester represented by the following formula (2) having repeating units each having a structure derived from each of three compounds of p-hydroxybenzoic acid, phthalic acid and biphenol. The repeating unit having a structure derived from the biphenol of the polyester represented by the following formula (2) may be a polyester in which a part or all of the repeating unit is substituted with a repeating unit derived from dihydroxybenzene. A polyester 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]

Embedded image

[0036]

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

A non-liquid crystalline resin may be blended with the thermotropic liquid crystal polymer for use. The resin that can be blended may be either a thermoplastic resin or a thermosetting resin, but is preferably a polyamide resin, a polycarbonate resin, a polyethylene terephthalate resin, a polybutylene terephthalate resin, a polyphenylene sulfide resin, a polyether sulfone resin, a polysulfone resin. Examples include so-called thermoplastic engineering plastics (non-liquid crystalline ones) such as polyetherketone resin and polyetheretherketone resin. The blending amount of the thermoplastic resin is 1 to 200 parts by weight, preferably 1 to 100 parts by weight, and more preferably 1 per 100 parts by weight of the thermotropic liquid crystal polymer in the present invention.
˜50 parts by weight.

A reinforcing agent or a filler may be added to the thermotropic liquid crystal polymer used in the present invention in order to further improve heat resistance and mechanical properties. Specific examples of the reinforcing agent or the filler include fibrous materials, powdery materials, and a mixture of both. As the fibrous reinforcing agent, glass fiber, shirasu glass fiber, alumina fiber, silicon carbide fiber, ceramic fiber, asbestos fiber, gypsum fiber, metal fiber (for example, stainless fiber etc.)
And other inorganic fibers and carbon fibers (including graphite fibers). Further, as the particulate reinforcing agent, wollastonite, sericite, kaolin, mica, clay, bentonite, asbestos, talc, silicates such as alumina silicate, alumina, silicon oxide, magnesium oxide,
Metal oxides such as zirconia and titanium oxide, carbonates such as calcium carbonate, magnesium carbonate and dolomite, calcium sulfate, calcium pyrophosphate, sulfates such as barium sulfate, glass beads, boron nitride, silicon carbide and saloyan. However, these may be hollow (for example, hollow glass fibers, glass microballoons, shirasu balloons, carbon balloons, etc.). The above-mentioned reinforcing agent can be used after being pretreated with a silane-based or titanium-based coupling agent, if necessary.

The thermoplastic resin used in the present invention, such as the thermotropic liquid crystal polymer, may be an antioxidant and a heat stabilizer (eg, hindered phenol, hydroquinone, phosphite, etc.) within the range not impairing the object of the present invention. And their substitution products), ultraviolet absorbers (eg resorcinol, salicylate, benzotriazole, benzophenone etc.), lubricants and mold release agents, dyes (eg nitrocin etc.), and pigments (eg cadmium sulfide, phthalocyanine, carbon black). Etc.), a general additive such as a colorant, a flame retardant, a plasticizer, an antistatic agent, etc. can be added to impart predetermined characteristics. The reinforcing agent, the filler, and the like can be added in an amount of 80% by weight or less, preferably 70% by weight or less, based on the entire resin composition.

In the case of injection molding a thermotropic liquid crystal polymer, the resin molding temperature is 200 to 42 as injection molding conditions.
0 ° C, mold temperature 60-170 ° C, more preferably 60-170 ° C
It can be appropriately selected from a range of 130 ° C., an injection pressure of 50 to 4000 kg / cm ² , and an injection speed of 5 to 1000 mm / sec.

Further, as an actuator according to an embodiment of the present invention, in an arm having three or more arm portions, the outermost two blades are thinner than the inner blades. To do. Normally, the two outermost blades have the same thickness, but they can have different thicknesses. When there are two or more inner blades, the inner blades may have the same or different thicknesses. In relation to the thickness of the outer and inner blades, it is more preferable that T1 / T2, where T1 is the thickness of the inner blade and T2 is the thickness of the outer blade.
Ratio of 1.05 to 2.0, more preferably 1.1 to
It is in the range of 2.0. For actuators, the thickness of the vanes on the outer and inner arms is 0.
It is appropriately selected from the range of 1 to 10 mm. Similarly, the length of the arm itself is usually in the range of 1 to 50 cm.

At the time of injection molding, the molten resin flows injected from the gate at any part of the arm part are filled in each arm part and finally join at a part opposite to the rotation axis. As a result of the arm portion having the thicker blades being filled earlier, the resin flow in the arm portion reaches the joining portion earlier.

Contrary to the above construction, when the outermost blade has a large thickness, the resin flow from the outer arm reaches early so that gas entrainment is likely to occur at the confluence. Become. This is not preferable because it leads to a decrease in mechanical strength. Although the gas is generated from a molten resin or a filler, a resin that melts at a higher temperature, such as an engineering plastic such as a thermotropic liquid crystal polymer, tends to generate gas, It is necessary to pay particular attention to gas entrapment. Therefore, the above structure is particularly advantageous when the thermotropic liquid crystal polymer is used.

[0044]

In this structure, the arms including the respective arm portions are simultaneously and integrally formed by injection molding. that time,
A resin portion, which is unnecessary as a product and connects the arm portions, is simultaneously and integrally molded. The intermediate product of the arm molded in this way and taken out from the mold is insufficiently solidified, but by sufficiently solidifying the unnecessary resin portion while being connected to each arm, the arm portion between Deformation and warpage are suppressed, and the parallelism between the arm portions is maintained. Therefore, the arm obtained by separating the unnecessary portion after being sufficiently solidified has high dimensional accuracy, and the yield is also improved.

Further, since the arms including the respective arm portions are simultaneously and integrally molded, the manufacturing process is shortened.

When a thermoplastic resin, particularly a thermotropic liquid crystal resin, is used for injection molding, the molecules are oriented in the direction in which the resin flows and the coefficient of linear expansion is close to that of a metal, so that dimensional accuracy is improved and rigidity is increased. improves.

Furthermore, when resin is injection-molded from the tip of the arm portion or in the vicinity thereof in the longitudinal direction of the arm portion, the molecules of the thermoplastic resin, for example, thermotropic liquid crystal polymer, are oriented in the flow direction. At this time, due to this orientation effect, the fibrous filler oriented in the polymer (preferably having an aspect ratio of 3 or more) is also strongly oriented in the flow direction at the same time. Therefore, the various functions such as the mechanical reinforcing effect of the fibrous filler given to the compounded resin are further improved by the above orientation. These various functions include, in addition to the reinforcing effect, reduction of surface resistance when a conductive and fibrous filler is used.

Here, since plastic is not essentially conductive, molded articles made of plastic, particularly electrical parts, are often provided with conductivity for reasons of static electricity and other reasons. For this purpose, it is also conceivable to incorporate a conductive filler including a fibrous filler.

However, the conductivity of the conductive filler itself cannot be sufficiently exhibited only by blending and injection molding. As described above, it is necessary to strongly orient the fibrous and conductive filler.
By strongly orienting like this, the conductivity is remarkably improved as compared with a product that is simply injection-molded and molded without orientation (without orientation). This conductivity is judged from the value of the surface resistance of the injection-molded product such as the arm portion.

For this purpose, in addition to metal fibers, metal-coated inorganic fibers, metal whiskers, etc., carbon fibers, graphite fibers, etc. may be mentioned. Carbon fibers and graphite fibers are preferable because they are usually electrically conductive and a mechanical reinforcing effect can be expected. The compounding amount of these fibrous fillers is selected from the range of the compounding amount of the above-mentioned filler.

[0051]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a plan view of an arm according to an embodiment of the present invention, and FIG. 2 is a sectional view taken along line AA of FIG. In these drawings, reference numeral 1 denotes an arm used for an actuator of a disk device (not shown), and a plurality of arm portions 2 (2a
Up to 2c) and integrally molded with resin.
Each arm portion 2 has integrally formed bush-shaped metal members 3a to 3c having through holes for attaching a head suspension (not shown). Further, the arm 1 has a shaft hole 6 through which its rotation shaft passes, and the shaft hole 6
Has a weld line on the side opposite to the arm tip, and at a portion outside the shaft hole 6 near the weld line, the convex portion 7 intersecting the weld line and the weld line are parallel to the weld line. It has a convex portion 8 extending in the direction. The thickness ratios of the outer arm portions 2a and 2c and the inner arm portion 2b are both 1.5.

The arm 1 is integrally molded by injection molding with a thermoplastic resin. As the thermoplastic resin, a thermotropic liquid crystal copolyester having repeating units derived from para-hydroxybenzoic acid, terephthalic acid, isophthalic acid and biphenol (showing optical anisotropy when melted by observation with a polarizing microscope) confirmed.
The melting point by DSC was 360 ° C. ) 100
A resin composition obtained by mixing 30 parts by weight of carbon fiber (aspect ratio 4) in parts by weight was used.

FIG. 5 shows a cross section corresponding to the cross section of FIG.
It is a partial sectional view of a mold for injection molding. FIG.
It is sectional drawing in the AA line of FIG. The mold is composed of mold parts 11 to 17, as shown in these figures. The mold portion 11 has a vertical pin (not shown) that models the inner walls of the holes 6 and 9 and a pin 18 for disposing the metal members 3a to 3c. The mold portion 17 is a portion corresponding to the sprue, runner, and gate (none of which is shown), and is divided along the line AA in FIG. In FIG. 5, only one of the parts is shown, but by combining it with the other part, sprue 1
9 and the runner 20. Mold part 1
2, 2, 13 and 14 and 15 are also divided into mold portions 12 and 13 and mold portions 14 and 15 along the line AA in FIG.

In injection molding, first, the metal member 3a
Is inserted into the pin 18 and placed at the lower end of the pin 18. Next, the mold parts 12 and 13 are arranged on the mold part 11 and the metal member 3a from the left and right directions when viewed in FIG. Next, the metal member 3b is inserted into the pin 18 and placed on the mold parts 12 and 13. Next, the mold parts 14 and 15
Similarly to the metal members 12 and 13 and the metal member 3b.
Place it on top. Next, the metal member 3c is inserted into the pin 18 and placed on the mold parts 14 and 15. Then, the mold portion 16 is inserted into the pin 18, and the mold portion 1
4 and 15 and the metal member 3c. Finally, the divided parts of the mold part 17 divided into two are opposed to each other, and the gate 20 part is made to correspond to the other mold parts 11 to 1.
The assembly of the mold is completed by inserting and arranging it into the tip portion of 6.

When the molten resin is injected through the sprue 19 and each runner 20 of the mold thus assembled for injection molding, the resin is injected into each gate 20.
'To the shaft hole 6 portion, and then wrap around to both sides of the shaft hole 6 portion to reach the weld line portion.
At this time, the resin molecules are oriented in the direction of this flow. Once the resin has solidified, the resin is used to move the mold to the mold parts 16, 14,
The mold is released by opening in the order of 15, 12, 13, 11, and 17 to obtain an intermediate product of the arm. This intermediate product is
The sprue 19 and runner 20 remain connected, and this connection is maintained until the resin is completely solidified. Then, when the resin is completely solidified, the arm can be obtained by cutting off the connecting portion composed of each sprue 19 and each runner 20.

Since the molecules of the arm thus obtained are oriented as described above, the coefficient of linear expansion of the arm is close to that of metal. That is, the resin molecules are oriented in the longitudinal direction of the arms since they are injection-molded from the tips of the arms, and the linear expansion coefficient in this direction is smaller than the linear expansion coefficient in the width direction (perpendicular direction). This tendency is remarkable in the thermotropic liquid crystal polymer, and in this liquid crystal polymer, the coefficient of linear expansion in the longitudinal direction of the arm portion is particularly small for a resin, which is close to that of a metal. A small linear expansion coefficient leads to good dimensional accuracy,
Since the longitudinal dimension of the arm of the actuator is important, it is extremely advantageous that the dimensional accuracy of the actuator is good especially in the longitudinal direction. Therefore, when the actuator is configured with this arm, the dimensional accuracy with respect to the metal portion is high and the rigidity is also high.

The time for solidifying the intermediate product is appropriately set depending on the resin, for example, in the range of 1 minute to several hours, and depending on the case, it is left for several days. Since the mold is usually cooled, it can be solidified by leaving it in the mold for a sufficient time. However, this is uneconomical because the molding time becomes too long.
Therefore, it is usually left after being taken out from the mold and sufficiently solidified, and then the connecting portion is cut and removed to form an arm.

There may be a method in which each arm is independently molded without forming a connecting portion, and after each arm is taken out of the mold, each arm is supported and fixed by an appropriate method until it is solidified. It is not preferable because each arm is easily deformed during operations such as taking out from the mold, supporting and fixing. This is because it is most easily deformed when taken out from the mold.

There may be a plurality of connecting portions between the arm portions. However, usually one connecting portion between each arm portion is sufficient. The preferred connection is made up of runners, sprues or both. The sprue, runner, etc. play a role of connecting the arm portions. The presence of these connecting portions reduces the relative positional displacement of each arm portion. For example, there is little deformation even with a protruding pin for demolding. Therefore, the structure of the connecting portion such as the sprue and the runner can be set to have such a length, width, and thickness that deformation due to the reinforcing effect is reduced. However, the thickness of the connecting portion is preferably the thickness of each arm portion of the arm in terms of manufacturing. According to the usual injection molding, there are runners and sprues. However, depending on how the gate is taken and other molding methods, the runner, sprue, etc. may form a molded body so as not to form a connecting portion.
Therefore, it is preferable to adopt a molding method in which the runner, the sprue, or both of them constitute the connecting portion. For example, as in this embodiment, a gate is provided at the tip of each arm portion or in the vicinity thereof, and a common sprue melts from each gate to each cavity forming each arm portion via a runner to each arm portion. It is preferred to inject the resin. The connecting part should be cut after the molten resin has solidified sufficiently.
To be removed. Therefore, if the connecting portion is constituted by the runner, the sprue, or both of them as described above, it is advantageous that there is no need to provide a special connecting portion because they are originally cut and removed. By molding the arm so that it surrounds the periphery of the movable coil and burying the terminal pins for connecting the coil conductors as necessary, the movable coil is fixed at the same time when the arm is molded.
It is also possible to integrate them. FIG. 3 is a plan view of an actuator according to another embodiment of the present invention manufactured as described above.

In this case, the coil 21 and the terminal pin 23 connected to the coil 21 or its holder 24 are set in the mold, and then the molten resin is injected from the tip end portion of each arm 2 as described above. A portion 22 that holds the coil 21 by flowing into the peripheral portion of the coil 21
Are molded simultaneously and integrally.

By doing so, the actuator can be manufactured by a method that requires a small number of members and a small number of steps.

[0062]

As described above, according to the present invention, the arms are prevented from warping and deforming because the arms are sufficiently solidified in the state of the intermediate product connected to each other and then the connecting parts are separated. It is possible to improve the positional accuracy between the arms and thus improve the yield.

Further, the presence of the connecting portion exerts a reinforcing effect and strengthens it. As a result, deformation due to the ejecting pin and the like at the time of releasing from the mold is preferable.

Further, since the resinization eliminates the need for machining, the equipment cost can be reduced.

Further, it is not necessary to stack the respective arm portions, the manufacturing process can be shortened, and the positional accuracy between the respective arm portions can be improved, so that the yield can be improved.

[Brief description of drawings]

FIG. 1 is a plan view of an arm according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along the line AA in FIG.

FIG. 3 is a plan view of an actuator according to another embodiment of the present invention.

FIG. 4 is a side view of a conventional actuator.

5 is a partial cross-sectional view of a mold for injection molding corresponding to the cross-sectional view of FIG.

6 is a cross-sectional view taken along the line AA in FIG.

[Explanation of symbols]

1: arm, 2: arm part, 3a to 3c: metal member,
6, 9: hole, 7, 8: convex portion, 11-17: mold portion,
18: pin, 19: sprue, 20: runner, 20 ':
Gate.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ken Motoi 242 Shimokobayashi-cho, Ota City, Gunma Prefecture (72) Inventor Yukio Iwataki 4-17-12 Higashiyukiya, Ota-ku, Tokyo

Claims (6)

[Claims] 1. An intermediate product of a thermoplastic resin arm for an actuator, wherein at least one resin connecting portion to be cut or removed is provided between a plurality of arm portions. 2. The intermediate product of the arm according to claim 1, wherein the resin connecting portion is a resin portion existing on a resin injection path at the time of injection molding. 3. The intermediate product of the arm according to claim 1, wherein the resin portion connects the vicinity of the tip of each arm portion. 4. A resin is used as an intermediate product of the arms in which each arm is connected by a resin portion which is unnecessary as a product to be simultaneously molded when these arms and the arm including them are simultaneously injection-molded. Molding by injection molding and taking it out of the mold, the step of fully solidifying the intermediate product taken out of the mold with the unnecessary resin parts connected to the arms, and the sufficiently solidified intermediate product. And a step of separating the unnecessary resin portion from the above. 5. An arm obtained by separating the unnecessary resin portion from the intermediate product according to claim 1, and a coil fixed to this arm for applying a force for swinging the arm to this arm. An actuator comprising: 6. An intermediate product of the arms, in which each arm is connected by a resin portion which is unnecessary as a product simultaneously molded when these arms and the arm including them are simultaneously injection-molded, in a mold. With the coil for swinging the arm set in, the step of molding by injection molding using resin and taking out from the mold, and the intermediate product taken out from the mold, the unnecessary resin part to each arm A method for manufacturing an actuator, comprising: a step of sufficiently breaking the connected product; and a step of separating the unnecessary resin portion from the fully solidified intermediate product.