JP3669415B2 - Deburring method for yoke part of voice coil motor for hard disk drive and voice coil motor - Google Patents

Description

◎：観察したすべてのヨーク部品において、バリは完全に除去されている。
○：バリはほぼ完全に除去されているが、わずかに残っているヨーク部品もある。
△：バリ除去に若干の効果はあったが、バリはまだ大半のヨーク部品で残っている。
×：観察したすべてのヨーク部品において、バリは全く除去されていない。
−：バリ除去処理前より該当するバリが存在しない。
【００４５】
なお、実施例において、［磁気研磨工程］を施した後、［化学研磨工程］を続いて行ったところ、表１に示す０．１ｍｍ以下のせん断バリを完全に除去することができた。
【００４６】
【発明の効果】
本発明によるハードディスクドライブ用ボイスコイルモーターの磁気回路を構成するバリ取りを施したヨーク部品の製造方法は、細かい細工をしている部分を含むすべての稜線に対するバリ除去に有効であり、ハードディスクドライブに有害なバリを除去した清浄なボイスコイルモーターの製造に極めて有効である。
【図面の簡単な説明】
【図１】ボイスコイルモーターの概略斜視図である。
【図２】ヨーク部品に存在するバリの態様を模式的に示すもので、（Ａ）はプレスしたヨークのせん断バリ、（Ｂ）は切削したヨークのヒゲ状バリの説明図である。
【図３】ヨーク部品の貫通穴に生じたバリの除去過程を模式的に示し、（Ａ）はバレル研磨前、（Ｂ）はバレル研磨後、（Ｃ）は磁気研磨後、（Ｄ）は化学研磨後の状態の説明図である。
【符号の説明】
１ ヨーク部品本体
２ 貫通穴
３ 研磨材
１１，１２ バリ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a deburring method for a surface of a yoke part that constitutes a magnetic circuit of a voice coil motor for a hard disk drive, and in particular, a yoke part that can remove burrs on all ridge lines including a finely crafted portion. It relates to the deburring method. The present invention also relates to a voice coil motor for a hard disk drive using a yoke part from which such burrs are removed.
[0002]
[Prior art and problems to be solved by the invention]
As shown in FIG. 1, the hard disk drive voice coil motor is mainly composed of a rare earth magnet a having high magnetic properties and a yoke part b constituting a magnetic circuit (in the figure, c is a coil), and in recent years, there has been an increasing demand for cleaning the magnetic head so that the head does not crash due to a decrease in the flying height of the magnetic head accompanying an increase in the storage capacity of the hard disk.
[0003]
Among these, especially yoke parts manufactured by press sheet metal, cutting, etc. mainly use low carbon steel to obtain excellent motor performance, but low carbon steel has a tendency to stick, There is a drawback that shear burrs and cutting burrs are likely to occur.
[0004]
In addition, as hard disk drives have become smaller year by year, the yoke parts that make up the magnetic circuit of the voice coil motor used for these hard disks have become smaller and more complex in shape, such as through holes, bending, screw holes, etc. There is an increasing number of finely crafted yoke parts, and the frequency of burrs tends to increase. For example, shear burrs or cutting burrs having a thickness or thickness of 0.5 mm or less often occur in through holes or screw holes having an outer diameter of about 3 mm. This burr is not only attached to the surface of the yoke part, but can easily fall off due to physical and chemical factors.
[0005]
Further, since the surface of the yoke part is plated with nickel, even if the burr does not fall off, the nickel powder on the surface may fall off when the burr receives an impact.
[0006]
The loss of burrs causes deterioration of the cleanliness of the voice coil motor for the hard disk drive. If the burrs that have fallen off during the operation of the hard disk drive collide with the magnetic head, problems such as head crashes occur. Particularly in recent years, the flying height of the head has become 0.1 μm or less, and burrs falling off of 0.5 mm or less can cause a head crash.
[0007]
Further, if the burr that has dropped off adheres to the hard disk, the burr exhibits ferromagnetism, which causes problems such as damage to recorded data. Particularly in recent years, the recording density of hard disks has become 1 gigabyte / cm ² or more, and omission of burrs of about 0.5 mm can also cause serious damage to recorded data.
[0008]
Various deburring methods have been proposed in order to remove burrs from yoke parts constituting the magnetic circuit of the voice coil motor for hard disk drive, but none of these methods are perfect as deburring methods. For example, removal of burrs by barrel polishing is effective for removing large burrs that occur on ridges on the outer periphery of yoke parts, but yokes that are subjected to fine work such as through holes, bending, and screw holes. The burr having a thickness or thickness of 0.5 mm or less present in the part has a disadvantage that it cannot be removed because the abrasive does not sufficiently collide.
[0009]
In addition, deburring by chemical polishing is effective for removing microburrs with a thickness or thickness of 0.1 mm or less that are present in the yoke component at any location of the entire yoke component. However, since the yoke component main body is melted by itself, there is a disadvantage that the burr having a thickness or thickness of 0.5 mm or less existing in the yoke component cannot be melted and removed. Normally, in chemical polishing, the thickness or thickness existing in the yoke part of a part that has been finely crafted such as a through-hole, bending process, screw hole or the like that is smaller than the diameter of the abrasive that cannot be removed by barrel polishing is 0. Although it is used for the purpose of supplementarily reducing burrs of 5 mm or less, as described above, it does not have an effect of completely removing these burrs.
[0010]
On the other hand, although magnetic polishing removes the thin whisker-like burrs that are generated by cutting, etc., the burrs generated by shearing have a shape with a wide root at the tip, and acicular ferromagnetism by magnetic polishing. This media has the disadvantage that it cannot be removed from the base even if it hits the burr, and is generally not used for deburring the yoke parts constituting the magnetic circuit of the voice coil motor for hard disk drive.
[0011]
In conventional technology, barrel polishing alone or chemical polishing after barrel polishing is the mainstream of deburring of yoke parts that make up the magnetic circuit of voice coil motors for hard disk drives. A burr having a thickness or thickness of 0.5 mm or less present in a yoke part in a finely crafted portion such as a hole cannot be removed and may be removed with a brush or the like.
[0012]
However, the parts that have been finely crafted to cause burrs are difficult to automate brushing because the shape of the yoke parts differs from product to product, and it is necessary to do it manually. There was a problem that it took too much.
[0013]
The present invention has been made in order to improve the above situation, and a hard disk capable of reliably and efficiently removing burrs present on all ridge lines including finely crafted portions of yoke parts. It is an object of the present invention to provide a deburring method for a yoke part constituting a magnetic circuit of a voice coil motor for a drive, and a hard disk drive voice coil motor using the deburred yoke part.
[0014]
Means for Solving the Problem and Embodiment of the Invention
As a result of earnest studies to achieve the above object, the present inventor first barrel-polished the low-carbon steel yoke part that has been subjected to shearing, cutting, etc. to produce burrs, and then By performing magnetic polishing, the finely crafted part of the entire yoke part, that is, a through-hole having an outer diameter of 10 mm or less in which barrel polishing abrasives cannot collide sufficiently and burrs are difficult to remove, It has been found that burrs existing on all ridge lines including screw holes, dents, and bent portions having a radius of 5 mm or less can be surely removed, and the present invention has been made.
[0015]
Accordingly, the present invention removes burrs existing on the surface of a yoke part having a through hole, a screw hole or a recess made of low carbon steel of a hard disk drive voice coil motor having a diameter of 10 mm or less, or a bent portion having a radius of 5 mm or less. The burr includes a burr having a thickness or thickness of 0.5 mm or less generated in the through hole, screw hole or indentation, or the ridge line of the bent portion due to the shearing process when the yoke part is manufactured. First, a barrel polishing process is performed in which a yoke part having the burr and a polishing material having a size of 3 to 20 mm collide with each other by rotation or vibration, and the root of the burr having a thickness or thickness of 0.5 mm or less is thinned. After that, in the magnetic field in which the N and S poles are alternately converted, the yoke component is fixed in a container in which the medium and the yoke component are placed, and the polarity of the magnetic field is converted. Deburring method yoke part and performing a polishing process, and providing a voice coil motor for a hard disk drive using a yoke parts burr has been removed by the deburring process.
[0016]
Hereinafter, the present invention will be described in more detail.
In the deburring to which the method of the present invention is applied, the burr is present in a yoke part constituting a magnetic circuit of a voice coil motor for a hard disk drive using low carbon steel, and particularly the thickness or thickness is 0.5 mm or less. This refers to burrs that occur on all ridges including the finely crafted parts. FIG. 2 schematically shows a burr embodiment, (A) shows the shear burr of the pressed yoke, (B) shows the mustard burr of the cut yoke, and shows the definition of the thickness and thickness of the burr. However, the present invention is not limited to this.
[0017]
In the deburring method of the present invention, a barrel polishing process and a magnetic polishing process are sequentially performed on the yoke part in which the above-described burrs are generated. Hereinafter, various processes performed in the present invention will be described.
[0018]
[Barrel polishing process]
Barrel polishing is a ridgeline where abrasives can sufficiently collide with the barrel, except for finely crafted parts such as through-holes, bending, and screw holes in the yoke parts that make up the magnetic circuit of a voice coil motor for hard disk drives. The purpose is to remove the generated burrs. At the same time, the thickness or thickness of the yoke parts in the finely crafted parts such as through-holes and bending are not enough to remove burrs caused by shearing with a thickness of 0.5 mm or less, At the same time, it has the purpose of making the shape easy to be removed in the next magnetic polishing step by forcibly rolling the base material by making the abrasive material collide to make the base narrow.
[0019]
Barrel polishing uses an abrasive whose main component is alumina, silica, magnesia, etc., and simultaneously seals the yoke parts and water added with rust prevention liquid in a rotating barrel, vibration barrel, centrifugal barrel, etc. And the yoke part can be made to collide with each other by rotation, vibration or the like. In this case, the size of the abrasive is not less than 3 mm, particularly not less than 5 mm, not more than 20 mm, particularly not more than 15 mm, and usually has a spherical or triangular shape of about 10 mm, and it is not desirable to add too fine abrasive grains. This is because abrasive grains remain in screw holes and indentations. Through this process, the thickness or thickness generated on the ridgeline where the abrasive material can sufficiently collide with the burr from various angles other than the finely crafted parts such as the through hole, bending process and screw hole of the yoke part. Burrs of 1.0 mm or less are removed. However, burrs with a thickness or thickness of 0.5 mm or less generated by shearing of finely crafted parts such as through holes and bending work can only be impacted from a limited direction of the abrasive and rolled. It has a shape like that and remains without being removed. However, the root is thinner than before barrel polishing, and it can be easily removed by deburring by magnetic polishing in the next step.
[0020]
In the conventional technology, the thickness or thickness existing in the yoke parts generated by shearing of the fine holes such as through holes and bending that are not removed in these barrel polishing processes is 0.5 mm or less. As described above, the film was left to stand or was dissolved and supplemented by chemical polishing to make it small, but not completely removed.
[0021]
[Magnetic polishing process]
The deburring by magnetic polishing is the thickness or thickness of the yoke parts in the finely crafted parts such as through holes, bending, screw holes, etc. of the yoke parts constituting the magnetic circuit of the voice coil motor for hard disk drive. The purpose is to remove burrs that cannot be removed by barrel polishing of 0.5 mm or less.
[0022]
Magnetic polishing is mainly in a magnetic field in which N and S poles alternately convert a container with a needle-shaped medium of φ0.2 to 1.0 mm and a length of about 5 mm and parts to be deburred using ferromagnetic stainless steel. Put on. At that time, the parts to be deburred and the cleaning liquid to prevent the media from being contaminated are also added. If the polarity of the magnetic field is changed violently, the media is ferromagnetic, so that the medium is violently disturbed and vibrated in accordance with the change of the magnetic field, and penetrates into finely crafted parts such as through holes, bending, and screw holes. , Hit the burr and remove. To convert the magnetic field in the container alternately between N and S is a method of installing the container between the electromagnets energized with alternating current, or a powerful magnet is installed alternately between the N and S under the pedestal on which the container is installed. This is achieved by a method of rotating the disk at high speed.
[0023]
Usually, a part to be deburred by magnetic polishing is a non-magnetic material. This is because burrs are difficult to remove because the ferromagnetic parts move in the same direction as the media as the magnetic field changes. However, by using a non-magnetic jig and fixing the ferromagnetic part in the container, the media can violently collide with the burr and can be removed.
[0024]
Since the yoke part is also a ferromagnetic body using low carbon steel, it is possible to remove burrs using magnetic polishing by fixing the yoke part using a jig. In that case, it is desirable to fix the shear direction of the yoke part parallel to the magnetic field direction in order to make the medium collide with the burr more reliably.
[0025]
Therefore, the input amount of the yoke part is determined by the size of the container and the design of the jig for fixing the yoke part. The frequency for converting the magnetic field is higher by using a method in which 50 to 60 Hz or more is used to vigorously disturb and vibrate the media, and a disk in which powerful magnets are alternately arranged is rotated at high speed. The magnetic field can be easily converted at the frequency.
[0026]
Regarding the shape of the media, barrels with a thickness or thickness of 0.5 mm or less of the finely crafted parts such as through holes, bending, screw holes, etc. of the yoke parts that constitute the magnetic circuit of the voice coil motor for hard disk drive A thick medium of about 0.5 to 1.0 mm may be selected according to the state of occurrence of burrs that cannot be removed by polishing. This is because when a thin medium of about 0.2 mm is used, since the medium is light, the effect of removing burrs is reduced. Usually, such a thin medium is used for removing burrs on resin-based parts such as plastic.
[0027]
The polishing time is set to about 1 to 10 minutes according to the burr generation status and the frequency for converting the magnetic field. After magnetic polishing, the yoke parts are wet and rusted easily, so it is desirable to immediately dry them with an oven, air blower, etc. after washing with water and removing the cleaning solution.
[0028]
As a result, the burr generated by shearing with a thickness or thickness of 0.5 mm or less present in the yoke parts of the finely crafted parts created in the punching press process such as through holes and bending, in particular, By forcibly rolling in the barrel polishing in the previous step and having a narrow base, it is possible to remove shear burrs generated by pressing that cannot be obtained by conventional magnetic polishing alone.
[0029]
In addition, since the roots of the whisker-like burrs generated by cutting finely crafted parts such as screw holes and depressions are thin, they are completely removed by the collision of the media by magnetic polishing.
[0030]
For such an apparatus, a magnetic polishing method [b (2)] JA G0937A Tool Engineer (JPN) 38 [2] 34-39 that can improve the efficiency of deburring and remove and remove fine burrs without deformation. '97).
[0031]
Here, when magnetic polishing is performed without performing barrel polishing in the previous process, the burr generated by shearing has a shape with a wide root at the tip, and a needle-like ferromagnetic medium by magnetic polishing. As described above, it is impossible to remove the burrs from the roots even if they collide with burrs, and burrs generated by shearing all the ridge lines including the finely crafted portions are not removed at all.
[0032]
In rare cases, the yoke parts that have been subjected to the barrel polishing process and the magnetic polishing process in sequence are subjected to shearing with a thickness or thickness of 0.1 mm or less existing in the yoke parts. In some cases, the fine burrs fall and adhere to the yoke component body, and the media cannot sufficiently collide and cannot be removed a little. If such a material is present, it is effective to remove it by dissolving it by chemical polishing for finishing. In chemical polishing, the yoke parts are immersed for 10 seconds to 10 minutes in an aqueous solution containing 1 to 40% of hydrogen peroxide, ammonium hydrogen fluoride or phosphoric acid as the main component, and the burrs are chemically dissolved and removed. To do.
[0033]
When performing chemical polishing, since the surface of the yoke part is activated, it is desirable to perform plating (nickel, copper, etc.) immediately after completion of chemical polishing by washing with water and pickling. In addition, the chemical polishing and plating process after the deburring process in the magnetic polishing can be processed continuously by using a jig or the like for fixing the yoke part in common. .
[0034]
FIG. 3 schematically shows a process in which shear burrs generated in the through holes are removed in each step of barrel polishing, magnetic polishing, and chemical polishing as an auxiliary finishing process. B) shows a state after barrel polishing, (C) shows a state after magnetic polishing, and (D) shows a state after chemical polishing. In the figure, 1 is a yoke part body, 2 is a through hole formed in the yoke part body, and before barrel polishing (A), a minute shear burr 11 is formed on the outer peripheral edge of the through hole 2 and the thickness is 0.5 mm or less. Shear burrs 12 are formed, and these burrs 11 and 12 protrude outward along the penetration direction of the through hole 2. These burrs 11 and 12 are both thick at the tip and cannot be removed by magnetic polishing alone. When barrel polishing is performed on the yoke component 1 in such a burr state (B), the abrasive 3 hits the burrs 11 and 12 and pushes the burrs 11 and 12 inwardly (through hole 2 direction). As a result, these burrs 11 and 12 are not removed by this barrel polishing, but are rolled to narrow the roots. In addition, as shown in the figure, the small shear burr 11 may fall on the inner peripheral wall of the through hole 2 and fall asleep (the tip side abuts against the inner peripheral wall). Next, when magnetic polishing is performed (C), as described above, the bases of the burrs 11 and 12 are thinned by barrel polishing, so that the burrs 11 and 12 are removed by magnetic polishing. However, the minute shear burr 11 that has fallen into the inner peripheral wall of the through hole 2 may not be removed. Even if such a small amount of the shear burr 11 remains, it is completely removed by performing chemical polishing (D). In the present invention, the deburring mode is not limited to FIG.
[0035]
Under the above conditions, the yoke parts that make up the magnetic circuit of a voice coil motor for hard disk drives are conventionally barrel-polished and magnetic-polished from large burrs to burrs with fine work such as through holes, bending, and screw holes. Including burrs on finely crafted parts generated by shearing with a thickness or thickness of 0.5 mm or less existing in yoke parts that could not be removed by using either alone. , All burrs are removed. By plating this, it is commercialized as a yoke component of a voice coil motor that does not need to worry about burrs falling off harmful to the hard disk drive.
[0036]
By using this yoke component and bonding and magnetizing the magnet, it can be commercialized as a voice coil motor that does not need to worry about burrs falling off harmful to the hard disk drive. The other components and configuration of the voice coil motor incorporating the yoke component can be known.
[0037]
【Example】
EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated concretely, this invention is not restrict | limited to the following Example.
[0038]
〔Example〕
Using a SPCC cold-rolled steel plate having a thickness of 3.2 mm, a yoke part having a weight of 30 g constituting a magnetic circuit of a voice coil motor for a hard disk drive was produced by press punching. The yoke has a flat plate shape with a diagonal of about 5 cm, but has two through holes with an outer diameter of 3 mm and one rolling tap with an outer diameter of 2.5 mm in the thickness direction. These are used for positioning when incorporating a voice coil motor into a hard disk drive. In the punched state, shear burrs are generated on all the press die side ridge lines including the ridge line of the through hole having an outer diameter of 3 mm. In addition, whisker-like burrs due to screwing are generated in the thread in the rolled tap hole having an outer diameter of 2.5 mm. The test piece was sequentially subjected to rotary barrel polishing and magnetic polishing under the following conditions.
[0039]
[Rotating barrel polishing process]
Yoke parts input 50 pieces x 30g
Outer 15mm spherical abrasive input 5kg
(Abrasive: Alumina and silica as main components)
Rotational speed 46r. p. m
Polishing time 1 hour [0040]
[Magnetic polishing process]
Media material: SUS304
Media shape: φ0.5 × 5L (mm)
Media input: 1kg
Container size: φ300 × 150H (mm)
Under the above conditions, the yoke parts were fixed upright on a Teflon jig, the medium and water were added, and the magnetic field was alternately generated at 60 Hz for 10 minutes to disturb and vibrate the medium.
[0041]
The yoke subjected to the above treatment was plated with nickel. In this case, normal burrs at the ridge line portion, shear burrs at the ridge line portion of the 3 mm outer diameter through hole, and whisker-like burrs of the 2.5 mm outer diameter rolled tap were observed. The results are shown in Table 1.
[0042]
[Comparative example]
For comparison, the following yokes were prepared at the same time, and the burr removal state was similarly evaluated.
(Comparative Example 1)
Only the [barrel polishing process] of the above process was performed.
(Comparative Example 2)
What carried out the [barrel polishing process] and the [chemical polishing process] of the above process.
(Comparative Example 3)
Performed only the [Magnetic polishing process] of the above process.
[0043]
In the [chemical polishing step], a chemical polishing liquid (CPL-100 manufactured by Mitsubishi Gas Chemical Co., Ltd.) mainly composed of hydrogen peroxide solution and ammonium hydrogen difluoride is diluted three times, and then at 20 ° C. for 1 minute. Processed.
These results are also shown in Table 1.
[0044]
[Table 1]

(Double-circle): The burr | flash is completely removed in all the yoke parts observed.
○: The burr is almost completely removed, but there are some yoke parts that remain slightly.
Δ: There was a slight effect in removing burrs, but burrs still remain in most yoke parts.
X: Burr is not removed at all in all observed yoke parts.
-: No corresponding burr exists before the burr removal treatment.
[0045]
In Examples, after [Magnetic Polishing Step] and then [Chemical Polishing Step], shear burrs of 0.1 mm or less shown in Table 1 could be completely removed.
[0046]
【The invention's effect】
The method of manufacturing a deburred yoke part constituting a magnetic circuit of a voice coil motor for a hard disk drive according to the present invention is effective for removing burrs on all ridge lines including finely crafted parts. It is extremely effective in manufacturing a clean voice coil motor that removes harmful burrs.
[Brief description of the drawings]
FIG. 1 is a schematic perspective view of a voice coil motor.
FIGS. 2A and 2B are diagrams schematically showing burrs present in a yoke part, where FIG. 2A is an explanatory view of shear burrs of a pressed yoke, and FIG.
FIGS. 3A and 3B schematically show a process of removing burrs generated in through holes of a yoke part, where FIG. 3A shows before barrel polishing, FIG. 3B shows after barrel polishing, FIG. 3C shows after magnetic polishing, and FIG. It is explanatory drawing of the state after chemical polishing.
[Explanation of symbols]
1 Yoke part body 2 Through hole 3 Abrasive material 11, 12 Burr

Claims (4)

  A method of removing burrs present on the surface of a yoke part having a through hole, a screw hole or a recess made of low carbon steel of a voice coil motor for a hard disk drive, or a bent portion having a radius of 5 mm or less, The burr includes a burr having a thickness or thickness of 0.5 mm or less generated in the ridgeline of the through hole, screw hole or indentation, or bending portion by shearing at the time of manufacturing the yoke part. After performing a barrel polishing process in which a yoke part and a polishing material having a size of 3 to 20 mm collide with each other by rotation or vibration, the base of the burr whose thickness or thickness is 0.5 mm or less is reduced, A magnetic polishing step is performed in which the yoke component is fixed in a container containing the media and the yoke component to convert the polarity of the magnetic field while the magnetic field is alternately converted. Deburring method of the yoke parts according to claim.   The deburring method according to claim 1, wherein after the magnetic polishing step, a chemical polishing step is performed in which the main component is immersed in an aqueous solution containing 1 to 40% of hydrogen peroxide, ammonium difluoride or phosphoric acid.   The deburring method according to claim 1 or 2, wherein the burr is generated by shearing at the time of manufacturing the yoke part, and the shearing direction of the yoke part is fixed parallel to the magnetic field direction in the magnetic polishing step.   A voice coil motor for a hard disk drive using a yoke part from which burrs are removed by the deburring method according to any one of claims 1 to 3.

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