JP2003260618A - Electro-chemical machining method, and electro-chemical machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electro-chemical machining method in which a work can be efficiently machined with high accuracy in a simple configuration, and a method for manufacturing a grove for a dynamic bearing. <P>SOLUTION: A surface of the work 23' is positioned to the depth of 5-35 mm from the level of electro-chemical solution stored in a storage part 41, and the work is subjected to the electro-chemical machining by feeding the electro-chemical solution is allowed to flow in a space between the work 23' and an electrode tool 35. Air, in particular, oxygen is least mixed in the electro- chemical solution, the excellent fluidity of the electro-chemical solution is maintained, and electro-chemical products after the electro-chemical machining are smoothly eliminated. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrolytic machining method and a dynamic pressure method in which an electrode tool and a work piece are opposed to each other via an electrolytic solution and electric current is applied to the work piece so that the work piece is electrolytically machined. The present invention relates to a method for manufacturing a bearing groove and a dynamic pressure bearing device manufactured by the manufacturing method.

[0002]

2. Description of the Related Art Electrolytic machining is carried out by concentrating electrolytic elution on a desired portion of a workpiece.
For example, an electrolytic processing apparatus as shown in FIG. 22 is conventionally known. In the electrolytic processing apparatus shown in FIG. 22, the jig 3 installed on the base 1 with the insulator 2 interposed therebetween.
The work piece 4 is placed on the work piece 4, and the electrode tool 5 is arranged to face the work piece 4 so as to face the work piece 4. The workpiece 4 is connected to the positive electrode (+ electrode) side of an electrolytic processing power source (not shown), and the electrode tool 5 is connected to the negative electrode (−) side.

On the other hand, the electrolytic solution 6 stored on the outside is supplied to the gap between the electrode tool 5 and the workpiece 4 through a filter 8 by a pump 7 as an electrolytic solution supply means, and the electrode tool While flowing the electrolytic solution 6 between the work piece 5 and the workpiece 4, electricity is applied between the two. As a result, the work piece 4 is electrochemically eluted and the work piece 4 is electrolytically machined.

At this time, the feeding device 1 is attached to the electrode tool 5.
0 is attached, and a predetermined machining gap (equilibrium gap) is maintained between the two as the electrode tool 5 is fed to the workpiece 4 side as the machining on the workpiece 4 progresses, and as a result, In addition, a shape that is the inverse of the shape of the electrode tool 5 is formed on the workpiece 4. The gas generated by the electrolytic processing is exhausted to the outside by the fan 11. Further, although various electrolytic products are contained in the electrolytic solution heated by Joule heat, the used electrolytic solution 12 is cleaned through the centrifugal separator 13, and
It is again supplied between the electrode tool 5 and the workpiece 4.

[0005]

However, the steps of mass production using such a general electrolytic processing method have the following problems. The working width of the workpiece tends to be larger than the width of the electrode tool, and the working width tends to vary. When the gap between the electrode tool and the work piece is reduced to reduce the variation in the working width, liquid clogging is caused by various particles such as electrolytic products from the work piece present in the electrolytic solution. It tends to occur and often causes processing defects. Similarly, if the gap between the electrode tool and the work piece is reduced, the flow of the electrolytic solution will not be good, and the electrolytic solution will easily deteriorate during processing, and the amount of processing on the inlet side of the electrolytic solution will increase. Is deep, and the working depth gradually decreases as it goes to the exit side. Part of the electrolytic solution or electrolytic product easily adheres to the work piece.

In particular, when electrolytic machining is used for machining the dynamic pressure generating groove in the dynamic pressure bearing device utilizing the dynamic pressure of the lubricating fluid, the dynamic pressure generating groove having a great influence on the dynamic pressure characteristics is The groove shape cannot be obtained with the required accuracy, so that good dynamic pressure characteristics cannot be obtained, and this also causes a decrease in productivity. Further, when the electrolytic product or the electrolytic solution remains attached to the processed product, the type of the rotating body supported by the dynamic pressure bearing device, such as a hard disk drive (HDD), is chemically There is also a risk of becoming unusable and becoming unusable.

Therefore, an object of the present invention is to provide an electrolytic machining method and a method for manufacturing a groove for a dynamic pressure bearing, which are capable of machining a workpiece with high precision and efficiency with a simple structure. And

[0008]

In order to achieve the above object, in an electrolytic machining method according to a first aspect of the present invention, at least the object to be machined and the electrode tool are arranged opposite to each other inside a machining accommodating portion for storing an electrolytic solution. A portion of the workpiece is housed so as to be submerged in the electrolytic solution, and the processed surface of the workpiece is 5 mm to 35 mm from the liquid surface of the electrolytic solution stored in the processed housing portion.
The position is set to a depth of mm, and the electrolytic solution is supplied so as to flow into the gap in the portion where the workpiece and the electrode tool are opposed to each other to perform electrolytic processing. According to the electrolytic processing method according to claim 1 having such a configuration, since the processing surface of the workpiece is positioned at a depth of 5 mm or more from the liquid surface of the electrolytic solution stored in the processing container, A high quality electrolytic processing is ensured because the amount of air, especially oxygen, is almost eliminated in the electrolytic solution.
Since the machining surface of the workpiece is positioned at a depth of less than or equal to mm, the fluidity of the electrolytic solution is maintained well, and the electrolytic products after electrolytic machining can be smoothly removed. Has become.

Further, in the electrolytic processing method according to claim 2, as the work piece according to claim 1, a material of a shaft member or a bearing member used in a dynamic pressure bearing device utilizing a dynamic pressure of a lubricating fluid is used, Since the groove for dynamic pressure generation is formed in the workpiece as the concave portion, the groove for dynamic pressure generation is processed with high accuracy.

Further, in the electrolytic machining method according to claim 3, on the surface of the workpiece to be machined according to claim 1,
A masking member having a through-hole pattern corresponding to the shape of the recess is formed in close contact with the mask, and the electrolyte is supplied while flowing into the gap between the masking member and the electrode tool. Since the electrolytic solution is made to flow by causing the electrolytic solution to enter and flow inside the pattern, the masking member in which the electrolytic solution supplied to the workpiece is brought into close contact with the workpiece. Even if the fluidity of the electrolyte is improved by widening the gap between the work piece and the electrode tool, the shape corresponding to the communication hole pattern of the masking member The concave part of
It is designed to be formed with higher accuracy on a workpiece.

In the electrolytic processing method according to claim 4,
Since a mixed solution with a surfactant is used as the electrolytic solution in claim 1, various particles such as electrolytic products eluted from the workpiece are absorbed by the surfactant in the electrolytic solution. The smooth flow of the electrolyte is ensured.

Further, in the electrolytic machining method according to claim 5, since the ultrasonic vibration generating means for applying ultrasonic vibration to the electrolytic solution according to claim 1 or claim 3 or claim 4 is provided, the workpiece to be processed is provided. Various particles such as electrolysis products eluted from the substance are made to flow smoothly by the ultrasonic vibration applied to the electrolytic solution.

On the other hand, in the electrolytic processing apparatus according to the sixth aspect of the present invention, the processing in which the electrolytic solution is stored and at least the portion where the workpiece and the electrode tool are opposed to each other are embedded in the electrolytic solution is stored. The work supporting member has an accommodating portion,
5 mm from the liquid surface of the electrolyte solution stored in the processing container
It is configured to position the work surface of the work piece at a depth of 35 mm. With the electrolytic processing apparatus according to claim 6 having such a configuration, the processed surface of the workpiece is positioned by the work supporting member at a depth of 5 mm or more from the liquid surface of the electrolytic solution stored in the processing container. Therefore, in the electrolytic solution, the amount of air, particularly oxygen, is almost eliminated, and high-quality electrolytic processing is ensured.
Since the processed surface of the workpiece is positioned by the work supporting member at a depth of 35 mm or less from the liquid surface of the electrolytic solution stored in the processing accommodating portion, the fluidity of the electrolytic solution can be maintained well. As a result, the electrolytic products after the electrolytic processing are smoothly removed.

Further, in the electrolytic processing apparatus according to a seventh aspect, as the work piece according to the sixth aspect, a material of the shaft member or the bearing member used in the dynamic pressure bearing device utilizing the dynamic pressure of the lubricating fluid is used, Since the groove for dynamic pressure generation is formed in the workpiece as the concave portion, the groove for dynamic pressure generation is processed with high accuracy.

Further, in the electrolytic processing method according to claim 8, on the surface of the workpiece to be processed of claim 6 above,
A masking member having a through-hole pattern corresponding to the shape of the recess is formed in close contact with the mask, and the electrolyte is supplied while flowing into the gap between the masking member and the electrode tool. Since the electrolytic solution is made to flow by causing the electrolytic solution to enter and flow inside the pattern, the masking member in which the electrolytic solution supplied to the workpiece is brought into close contact with the workpiece. Even if the fluidity of the electrolyte is improved by widening the gap between the work piece and the electrode tool, the shape corresponding to the communication hole pattern of the masking member The concave part of
It is designed to be formed with higher accuracy on a workpiece.

Further, in the electrolytic processing apparatus according to claim 9,
Since a mixed solution with a surfactant is used as the electrolytic solution in claim 6, various particles such as electrolytic products eluted from the workpiece are absorbed by the surfactant in the electrolytic solution to cause electrolysis. A smooth flow of liquid is ensured.

Further, in the electrolytic processing apparatus according to claim 10, since the ultrasonic vibration generating means for applying ultrasonic vibration to the electrolytic solution according to claim 6, 8 or 9, is provided, the electrolytic processing apparatus is processed. Various particles such as electrolysis products eluted from the substance are made to flow smoothly by the ultrasonic vibration applied to the electrolytic solution.

Furthermore, in the electrolytic processing apparatus according to the eleventh aspect, since the insulating member is provided on at least the surface portion of the masking member according to the eighth aspect, the portion other than the communication hole pattern in the masking member is energized. Is almost completely cut off, and the shape of the recess is formed with higher accuracy.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Prior to that, a hard disk drive (HDD) as an example to which the manufacturing method according to the present invention is applied is applied. The overall structure will be explained.

The entire shaft-rotating HDD spindle motor shown in FIG. 8 has a stator assembly 10 as a fixing member.
And a rotor set 20 as a rotating member assembled to the stator set 10 from the upper side in the drawing. The stator set 10 has a fixed frame 11 screwed to the fixed base side (not shown). The fixed frame 11 is formed of an aluminum-based metal material for the purpose of weight reduction, but the inner peripheral surface of the annular bearing holder 12 formed so as to stand upright in the substantially central portion of the fixed frame 11. On the side, a bearing sleeve 13 as a fixed bearing member formed in a hollow cylindrical shape is joined to the bearing holder 12 by press fitting or shrink fitting. The bearing sleeve 13 is formed of a copper-based material such as phosphor bronze in order to facilitate drilling of small-diameter holes.

A stator core 14 made of a laminated body of electromagnetic steel plates is fitted on the outer peripheral mounting surface of the bearing holder 12. A drive coil 15 is wound around each salient pole portion provided on the stator core 14.

Further, the rotary shaft 21 constituting the above-mentioned rotor set 20 is rotatably inserted into the center hole provided in the bearing sleeve 13. That is, the dynamic pressure surface formed on the outer peripheral surface of the rotary shaft 21 is arranged so as to closely face in the radial direction with respect to the dynamic pressure surface formed on the inner peripheral wall portion of the bearing sleeve 13. The radial dynamic pressure bearing portion RB is formed in the minute gap portion. More specifically, the dynamic pressure surface on the bearing sleeve 13 side of the radial dynamic pressure bearing portion RB and the dynamic pressure surface on the rotary shaft 21 side are circumferentially opposed to each other with a minute gap of several μm therebetween. Lubricating fluid such as lubricating oil, magnetic fluid, and air is injected or interposed so as to be continuous in the axial direction in the bearing space formed of a minute gap.

Further, on at least one side of both the dynamic pressure surfaces of the bearing sleeve 13 and the rotary shaft 21, a herringbone-shaped radial dynamic pressure generating groove (not shown) is divided into two blocks in the axial direction. It is provided with a ring-shaped recess, and at the time of rotation, the lubricating fluid is pressurized by the pumping action of the radial dynamic pressure generating groove to generate dynamic pressure, and the dynamic pressure of the lubricating fluid together with the rotary shaft 21 will be described later. The rotating hub 22 is axially supported in the radial direction in a non-contact state with the bearing sleeve 13.

At this time, the rotary hub 22 that constitutes the rotor set 20 together with the rotary shaft 21 is made of a substantially cup-shaped member, and the joint hole 22a provided in the central portion of the rotary hub 22 has the above-mentioned rotary shaft 21. The upper end portion 21 of the drawing is integrally joined by press fitting or shrink fitting. A recording medium such as a magnetic disk is fixed to the rotary hub 22 by a clamper (not shown). That is, the rotary hub 22 has a substantially cylindrical body portion 22b for mounting the recording medium disc on the outer peripheral portion, and an annular drive magnet 22c is provided on the inner peripheral wall surface side of the lower portion of the body portion 22b in the figure. It is installed.
The annular drive magnet 22c is closely arranged so as to face the outer peripheral side end surface of the stator core 14 in an annular shape.

On the other hand, as shown in FIGS. 9, 10 and 11, a disk-shaped thrust plate 23 is fixed to the tip end portion of the rotary shaft 21 on the lower end side in the figure by plate fixing screws 24. ing. This thrust plate 2
3 is arranged so as to be housed in a cylindrical recess 13a (see FIG. 8) which is provided in the center of the lower end side of the bearing sleeve 13 shown in the drawing.
In the recessed portion 13a of the thrust plate 2
The dynamic pressure surface provided on the upper surface of the bearing sleeve 3 in FIG.
It is arranged so as to be close to the dynamic pressure surface provided in 3 in the axial direction.

A thrust dynamic pressure generating groove 23a formed in a herringbone shape as shown in FIG. 10 is formed on the dynamic pressure surface of the thrust plate 23 on the upper side in the drawing by an electrolytic processing method described later. Has been done,
An upper thrust dynamic pressure bearing portion SBa is formed in a gap portion between the dynamic pressure surfaces of the thrust plate 23 and the bearing sleeve 13 which face each other.

Further, a counter plate 16 made of a disk-shaped member having a relatively large diameter is arranged so as to be close to the dynamic pressure surface on the lower side of the thrust plate 23 in the drawing. The counter plate 16 is arranged so as to close the opening portion on the lower end side of the bearing sleeve 13, and the outer peripheral side portion of the counter plate 16 is
It is fixed to the bearing sleeve 13 side.

A herringbone-shaped thrust dynamic pressure generating groove 23b as shown in FIG. 9 is formed on the dynamic pressure surface of the thrust plate 23 on the lower side in the drawing by an electrolytic processing method described later. ,Thereby,
A thrust dynamic pressure bearing portion SBb on the lower side in the drawing is formed.

In this way, both dynamic pressure surfaces on the thrust plate 23 side, which constitute a set of thrust dynamic pressure bearing portions SBa, SBb arranged adjacent to each other in the axial direction, and the bearing sleeve 13 and the bearing sleeve 13 which closely oppose to each other. Counter plate 16
The two hydrodynamic pressure surfaces on the side are axially opposed to each other through a minute gap of several μm, and a lubricating fluid such as oil, magnetic fluid, or air is disposed in the bearing space formed of the minute gap. Injected or interposed so as to be continuous in the axial direction through the outer peripheral side passage of the thrust plate 23,
At the time of rotation, the lubricating fluid is pressurized by the pumping action of the thrust dynamic pressure generating grooves 23a and 23b provided in the thrust plate 23 described above to generate dynamic pressure, and the dynamic pressure of the lubricating fluid causes the rotary shaft 21 described above to rotate. And the rotating hub 22
Is configured so as to be axially supported in a non-contact state that floats in the thrust direction.

Next, the structure of the electrolytic processing apparatus used to manufacture the thrust dynamic pressure generating grooves 23a and 23b in the thrust plate 23 according to the present invention will be described.

As shown in FIGS. 1, 2, 3 and 4, a concave portion for mounting a work is provided at a substantially central portion of the work supporting jig 32 mounted on the main body base portion 31. The material of the thrust plate 23 (hereinafter referred to as the thrust plate material) 23 'as the above-mentioned workpiece is held in the work mounting recess in a horizontal state so as to be dropped. There is. The thrust plate material 23 'in this embodiment is made of a stainless material.

Further, a masking member 33 made of a thin plate-like insulating member is attached to the surface of the thrust plate material 23 'on the upper side in the figure so as to be in close contact therewith.
The masking member 33 is made of a disk-shaped member having a diameter larger than the outer diameter of the thrust plate material 23 ′, and the outer peripheral edge portion of the masking member 33 is provided by the cap-shaped member 34 to the work supporting jig 32 side. It is fixed so as to be pressed downward in the drawing.

Further, as shown in FIG. 3, the masking member 33 has a communicating hole pattern 33 having a shape corresponding to the thrust dynamic pressure generating grooves 23a and 23b.
a is formed through. This masking member 33 is
It suffices that the insulating material is formed on at least the surface portion, and for example, a thin ceramic material, a stainless steel plate (SUS) coated by electrodeposition or ceramics, or a resin plate is used. The plate thickness of the masking member 33 is, for example, 0.0
The thickness is set to about 5 mm to 0.1 mm.

On the other hand, an electrode tool 35 made of a hollow rod-shaped member is arranged right above the thrust plate material 23 'and the masking member 33 so as to stand in a substantially vertical direction. The electrode tool 35 includes a body arm portion 36 extending above the body base portion 31.
Is fixed or held at the lower end portion of the electrode tool 35 in the figure between the masking member 33 and
It is arranged so as to form a gap δ of about 1 mm during electrolytic processing. Further, on the side of the electrode tool 35, for example, a negative electrode (−) of a direct current power source having an output voltage of about 5 V to 15 V is connected, and the positive electrode (+ pole) of the direct current power source is a workpiece. Is connected to the thrust plate material 23 'side.

Further, a liquid passage 35a is formed through the central portion of the electrode tool 35 in the axial direction. From the upper end side of the liquid passage 35a shown in the figure, an electrolytic solution supply means (pump not shown) is provided. ), The electrolytic solution is supplied. The electrolytic solution at this time is
For example, a 10 to 30 wt% solution of NaNo ₃ is used, and the electrolyte solution fed from the upper side of the electrode tool 35 in the drawing passes through the liquid passage 35a and the outlet provided in the lower end side of the drawing. It is supplied so as to fall onto the masking member 33 and the thrust plate material 23 '.
The electrolytic solution supplied to the central portion radially flows outward in the radial direction and is stored in a tray (not shown). In addition, as the electrolytic solution,
3-10 wt% KOH, 3-10 wt% NaOH,
5 to 15% by weight of Na ₂ Co ₃ or the like may be used.

On the other hand, the above-mentioned electrolytic solution is appropriately stored in the processing accommodating portion 41 provided so as to cover the facing arrangement portion of the thrust plate material 23 'as the workpiece and the electrode tool 35 from the outer peripheral side. It is designed to flow while the amount is stored. The processing accommodating portion 41 includes an annular wall portion 41a that is provided upright on the upper surface side in the figure of the cap member 34 of the work supporting jig 33 described above. A predetermined liquid level is provided inside the annular wall portion 41a. The electrolyte is stored so that it has a height, and in the electrolyte,
The thrust plate material 23 ′ and the electrode tool 35 facing each other are arranged so as to be buried.

At this time, the processing surface on the upper surface side of the thrust plate material 23 ′ as the workpiece held by the work supporting jig 33 is the processing accommodating portion 4 described above.
5 mm to 35 mm from the liquid surface of the electrolyte solution stored in 1
It is positioned so as to be located at a depth within the range.
The reason for positioning at a depth within the range of 5 mm to 35 mm in the electrolytic solution will be described later.

While allowing the electrolytic solution to flow in the gap δ between the electrode tool 35 thus set in the electrolytic solution and the masking member 33 and the thrust plate material 23 ', the electrode tool 35 and the thrust plate are Energize with the material 23 '. In this case, the masking member 33
The electrolytic solution flows into the inside of the communication hole pattern 33a provided in the thrust plate material 23 '.
The electrolytic solution flows while contacting the exposed surface of the masking member 33 in FIG. Then, the portion of the thrust plate material 23 ′ that has come into contact with the electrolytic solution is electrochemically eluted, whereby the thrust plate material 2
3'electrolytic machining is performed.

At this time, a vibrator 37 constituting ultrasonic vibration generating means is attached to the uppermost end portion of the electrode tool 35. As the vibrator 37 in the present embodiment, a horn type amplifier that amplifies the applied amplitude to about 20 to 22 μm is used, and by vibrating the electrode tool 35, the above-mentioned electrolytic solution is applied. It is configured to provide ultrasonic vibration.

In the present embodiment, the energization for electrolytic machining and the energization for ultrasonic vibration are configured to be performed independently, and the actual energization mode is as shown in FIG. A rectangular pulse current is used to alternately perform energization Pa for electrolytic machining and energization Pb for ultrasonic vibration,
As shown in FIG. 6, a relatively long width of the electric current Ca for electrolytic machining and an electric current Cb for ultrasonic vibration may be partially overlapped with each other. In either method, particles such as electrolytic products can be removed by ultrasonic vibration while performing electrolytic processing.

Further, a mixed solution of a surfactant is used as the electrolytic solution. As the surfactant in this embodiment, a nonionic surfactant such as an alkyl ether-based surfactant is used, and the added amount is 0.03% or more by volume. The reason why the amount is added is based on the experimental results shown in Table 1 below.

That is, in Table 1 below, the inner diameter is 5.0 m.
m, 12 mm thick stainless steel (SUS420) material to be processed, electrolytic treatment was performed for 60 seconds each while changing the concentration of the surfactant from 0% to 5%, and the electrolytic solution after the electrolytic processing. It represents the number of residual metal chips contained therein.

[Table 1]

From Table 1, as compared with the case where the surfactant is 0% by volume, the number of residual metal chips is remarkably reduced when the ratio is 0.03% or more by volume, and It can be seen that the activator works efficiently. Further, when the volume ratio is set to 2% or more, the number of residual metal chips is almost zero. On the other hand, the volume ratio of the surfactant is 5
Since the characteristics of the processing itself do not change even if the volume ratio is increased to more than the% volume ratio, it is preferable to set the volume ratio to about 2%.

According to the electrolytic machining method of the dynamic pressure bearing device using the electrolytic machining apparatus having such a configuration, the electrolytic solution supplied to the thrust plate material 23 ′ as the workpiece is the thrust plate material 23. It is made to flow only in the communication hole pattern 33a of the masking member 33 that is brought into close contact with the ', and the gap between the masking member 33 and the thrust plate material 23' and the electrode tool 35 is widened to improve the fluidity of the electrolytic solution. Even if the height is increased, the dynamic pressure generating grooves 23a and 23b having a shape corresponding to the communication hole pattern 33a of the masking member 33 are formed in the thrust plate material 2
3'is formed with high precision.

In particular, in this embodiment, the processing surface of the thrust plate material 23 'as the workpiece is the processing container 4
Since it is positioned at a depth of 5 mm or more from the liquid surface of the electrolytic solution stored in 1, the amount of air, particularly oxygen, mixed in the electrolytic solution is almost eliminated, and high-quality electrolytic processing is ensured. It has become. Further, since the processed surface of the thrust plate material 23 ′ as the work piece is positioned at a depth of 35 mm or less from the liquid surface of the electrolytic solution stored in the processing accommodating portion 41, the fluidity of the electrolytic solution is reduced. Is favorably held, and the electrolytic products after electrolytic processing are smoothly removed.

Actually, the relation between the depth from the liquid surface of the electrolytic solution on which the machining surface of the thrust plate material 23 'as the workpiece to be machined is positioned and the machining depth by electrolytic machining was measured. Table 2 and FIG.

[Table 2]

That is, as is apparent from Table 2 and FIG. 7, the processed surface of the thrust plate material (stainless material) 23 ′ as the workpiece is the point A in FIG.
In other words, if it is set to a position shallower than 5 mm,
Electrolytic smut (dissolved residue) on electrolytically processed parts
The tendency is to occur. On the other hand, when the positioning depth of the processing surface exceeds point B in FIG. 7, that is, 35 mm, the processing depth changes so that a voltage drop occurs and the processing depth becomes shallow.

On the other hand, the positioning depth of the processed surface is from the point A (5 mm) to the point B (35 m) as in the present invention.
It has been found that the machining depth by electrolytic machining is fairly stable when it is set up to m). At this time,
Even if the voltage value, current value, pulse width, etc. for executing electrolytic machining are changed, the machining depth value will also fluctuate somewhat, but as mentioned above, a range where a stable machining depth can be obtained. Was almost unchanged in any case, and extremely good results were obtained within a range of 5 mm to 35 mm under various conditions.

Further, in the electrolytic processing according to the present embodiment, since the masking member 33 described above is formed of an insulating member, the energization to the portion of the masking member 33 other than the communication hole pattern 33a is almost completely cut off. The dynamic pressure generating grooves 23a, 2
The shape of 3b is formed with higher precision.

Furthermore, in the electrolytic processing in the present embodiment, since the mixed solution with the surfactant is used as the electrolytic solution, electrolytic products such as the electrolytic products from the thrust plate material 23 'as the workpiece are processed. Various particles
The smooth flow is ensured by being absorbed by the surfactant in the electrolytic solution.

In addition, in the electrolytic processing in this embodiment, the ultrasonic vibration generating means 3 for applying ultrasonic vibration to the electrolytic solution is used.
Since 7 is provided, various particles such as electrolytic products eluted from the work piece can be smoothly flowed by the ultrasonic vibration applied to the electrolytic solution.

At this time, in this embodiment, energization for electrolytic machining and energization for ultrasonic vibration are performed independently, and energization Pa and Ca for electrolytic machining and energization P for ultrasonic vibration are performed.
b and Cb are alternately performed or at least a part of each of the energizations thereof are overlapped, so that the energization for the electrolytic machining and the energization for the ultrasonic vibration are performed according to the situation of the electrolytic machining. By appropriately switching, the best processing state can be always obtained.

Next, in the embodiment shown in FIGS. 12, 13, 15, and 16, the central portion of the masking member 33 has a supply port 33a for receiving the electrolytic solution.
Are formed so as to penetrate in the axial direction, and further, from the supply port 33a, the thrust dynamic pressure generating groove 2 described above is formed.
Communication hole pattern 33 including shapes corresponding to 3a and 23b
b is formed so as to extend radially outward. Each of the communication hole patterns 33b is formed so as to penetrate in the axial direction, but the thrust dynamic pressure generating grooves 23a and 23b are shaded in FIG.
Is provided so as to further extend outward in the radial direction from the outer peripheral edge portion (broken line in the drawing) of the portion corresponding to. And, in the extension end portion in the radial direction outward,
The discharge port 33c is provided for discharging the electrolytic solution to the outside.

At a position directly above the masking member 33, the masking member 33 is brought into contact with the masking member 33.
An electrode tool 35 formed of a hollow rod-shaped member is arranged so as to stand upright in a substantially vertical direction. This electrode tool 35 is
It is fixed to the main body arm portion 36 extending above the main body base portion 31 described above, and the lower end portion of the electrode tool 35 shown in the figure is in close contact with the upper surface side of the masking member 33 shown in the figure. It is arranged so as to be pressed downward in the direction.

On the other hand, also in this embodiment, the electrolytic solution is
Flowing is performed while an appropriate amount is stored in the processing accommodating portion 41 provided so as to cover the facing arrangement portion of the thrust plate material 23 ′ as the workpiece and the electrode tool 35. . The processing accommodating portion 41 includes an annular wall portion 41a that is erected on the upper surface side of the work supporting jig 32 in the figure, and has a predetermined liquid level height inside the annular wall portion 41a. Electrolyte is stored like
In the electrolytic solution, the above-mentioned thrust plate material 23 '
The opposing arrangement portion of the electrode tool 35 and the electrode tool 35 is configured to be buried.

The processing surface on the upper surface side of the thrust plate material 23 'as a workpiece held by the work supporting jig 32 on the upper side in the drawing is the processing accommodating portion 41.
It is positioned so as to be located at a depth within a range of 5 mm to 35 mm from the liquid surface of the electrolytic solution stored therein.

In this way, the electrolytic solution supplied from the electrode tool 35 to the central portion of the masking member 33 has the communication hole pattern 33b provided in the masking member 33.
Of the thrust plate material 23 ′ while coming into contact with the exposed surface of the thrust plate material 23 ′ and flowing toward the outer side in the radial direction. At that time, if electricity is applied between the electrode tool 35 and the thrust plate material 23 ', the portion of the thrust plate material 23' which is in contact with the electrolytic solution will be electrochemically eluted, and The electrolytic processing of the thrust plate material 23 'is performed.

At this time, each of the communication hole patterns 33b of the masking member 33 has the thrust plate material 2
3'is provided so as to extend to the outer side in the radial direction, and the electrolytic solution flowing in the communication hole pattern 33b from the outer peripheral edge of the thrust plate material 23 'toward the outer side in the radial direction is Each of the communication hole patterns 33b is discharged to the outside from a discharge port 33c provided in the outermost peripheral portion, is stored in a tray (not shown), and is then recirculated.

In the electrolytic processing of the dynamic pressure bearing device according to the present embodiment, the communication hole pattern 33b of the masking member 33 is extended from the outer peripheral edge of the thrust plate material 23 'to the outer side in the radial direction. Communication hole pattern 33
Since the electrolyte solution is discharged from the discharge port 33c provided at the outwardly extended end portion of b, the electrolyte solution supplied from the electrode tool 35 is good on the inner side of the communication hole pattern 33b of the masking member 33. It is becoming more fluid.

On the other hand, also in the embodiments shown in FIGS. 17, 18 and 21, a work mounting recess is provided in a substantially central portion of the work supporting jig 32 mounted on the main body base 31. And the thrust plate 23 as the above-mentioned workpiece is provided in the workpiece mounting recess.
Material (hereinafter referred to as thrust plate material) 23 '
However, it is installed so as to be dropped. Then, at a position directly above the thrust plate material 23 ',
The electrode tool 35 made of a rod-shaped member is arranged so as to stand in a substantially vertical direction. The electrode tool 35 is held by the main body arm portion 36 extending above the main body base portion 31 described above, and the lower end portion of the electrode tool 35 in the drawing is located between the thrust plate material 23 ′. To
It is arranged so as to form a gap δ.

At this time, a pattern 35a having a shape corresponding to the thrust dynamic pressure generating grooves 23a, 23b is formed on the tip end surface of the electrode tool 35 on the lower end side in the drawing, as shown in FIGS. It is formed to have a convex shape. At this time, portions other than the pattern 35a are filled with an insulator 35b such as resin, and the tip end surface of the electrode tool 35 is formed to be a flat surface. The tip surface including the pattern 35a is arranged so as to face the thrust plate material 23 '.

On the other hand, in the gap δ between the electrode tool 35 and the thrust plate material 23 'as the workpiece,
The electrolytic solution is supplied so as to flow in a direction substantially orthogonal to the axial direction. The electrolytic solution is supplied by an electrolytic solution supply means (pump) (not shown), but in the present embodiment also, the electrolytic solution is supplied to the thrust plate material 23 ′ as the workpiece. Flowing is performed while an appropriate amount is stored in the processing accommodating portion 41 that is provided so as to cover the portion facing the electrode tool 35. The processing accommodating portion 41 includes an annular wall portion 41a that is erected on the upper surface side of the work supporting jig 32 in the figure, and has a predetermined liquid level height inside the annular wall portion 41a. The electrolytic solution is stored like this, and in the electrolytic solution,
The thrust plate material 23 'and the electrode tool 35 facing each other are arranged to be buried in the facing portion.

At this time, the machining surface on the upper surface side of the thrust plate material 23 ′ as the workpiece held by the work supporting jig 32 is the machining accommodating portion 4 described above.
5 mm to 35 mm from the liquid surface of the electrolyte solution stored in 1
It is positioned so as to be located at a depth within the range.

In the present embodiment having such a configuration, even when the electrode tool 35 is brought close to the thrust plate material 23 ′ as the workpiece, the thrust is generated by the ultrasonic vibration applied to the electrolytic solution. Various particles such as electrolytic products eluted from the plate material 23 'are smoothly flowed to maintain good electrolytic processing, and the shape of the pattern 35a provided on the electrode tool 35 side is the thrust plate material 23'. It is accurately formed on the side.

Although the embodiments of the invention made by the present inventor have been specifically described above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the invention. Needless to say.

For example, in the above-described embodiment, the stainless material is used as the work piece (thrust plate material 23 '), but the present invention can be similarly applied to copper-based metals such as phosphor bronze. it can.

Further, in the above-described embodiment, the present invention is applied to a dynamic pressure bearing device for a hard disk drive motor (HDD), but other dynamic pressure bearing devices,
Furthermore, it can be similarly applied to electrolytic processing methods for a wide variety of workpieces.

[0068]

As described above, the electrolytic processing method according to claim 1 or the electrolytic processing apparatus according to claim 6 of the present invention is 5 mm from the liquid surface of the electrolytic solution stored in the processing container.
The machining surface of the work piece is positioned to a depth of ~ 35 mm to almost eliminate the amount of air, particularly oxygen, mixed in the electrolytic solution, and to maintain good fluidity of the electrolytic solution to prevent electrolysis after electrolytic processing. Since the product is smoothly removed, high-quality and extremely high-precision electrolytic processing can be easily realized.

Further, the electrolytic processing method according to claim 2 of the present invention or the electrolytic processing device according to claim 7 uses the dynamic pressure of a lubricating fluid as the workpiece to be processed according to claim 1 or claim 6. By using the material of the shaft member or the bearing member used in the dynamic pressure bearing device and forming the groove for dynamic pressure generation as the recess in the workpiece, particularly, the groove for dynamic pressure generation is processed with high accuracy. Thus, the dynamic bearing device can be manufactured with high quality and extremely high precision.

Further, the electrolytic processing method according to claim 3 of the present invention or the electrolytic processing apparatus according to claim 8 is characterized in that the shape of the recess is formed on the surface of the workpiece to be processed in claim 1 or 6. A masking member having a through-hole pattern corresponding to the above is closely contacted, and the electrolytic solution is supplied while flowing into the gap between the masking member and the electrode tool, and the through-hole pattern in the masking member is provided. The electrolytic solution is introduced into the inside of the to make it flow and the electrolytic processing is performed, and the electrolytic solution is allowed to flow only in the communication hole pattern of the masking member that is brought into close contact with the workpiece to correspond to the communication hole pattern. Since the concave portion having the above-described shape is formed easily and with high precision in the workpiece, it is possible to perform high-precision electrolytic processing at a low cost with a simple configuration. The utility of the factory can be remarkably improved.

Further, the electrolytic processing method according to claim 4 or the electrolytic processing apparatus according to claim 9 uses an electrolytic solution prepared by using a mixed solution with a surfactant as the electrolytic solution according to claim 1 or claim 6. Since the smooth flow is ensured, the above effect can be further enhanced.

Furthermore, the electrolytic processing method according to claim 5 or the electrolytic processing apparatus according to claim 10 is the same as in claim 1 or claim 3 or claim 4 or claim 6 or claim 8 or claim 9. By providing ultrasonic vibration generating means for applying ultrasonic vibration to the electrolytic solution, the electrolytic solution containing various particles such as electrolytic products eluted from the workpiece is smoothly flowed by ultrasonic vibration. The effects described above can be further enhanced.

Furthermore, in the electrolytic processing apparatus according to the eleventh aspect, an insulating member is provided on at least the surface portion of the masking member according to the eighth aspect so that the energization to a portion other than the communication hole pattern in the masking member is almost completely cut off. However, since the shape of the concave portion is formed with higher accuracy, the above-described effect can be further improved.

[Brief description of drawings]

FIG. 1 is a front cross-sectional explanatory view showing a schematic structure of an embodiment of an electrolytic processing apparatus according to the present invention.

2 is a side cross-sectional explanatory view showing a schematic structure of the electrolytic processing apparatus shown in FIG.

FIG. 3 is an explanatory plan view showing the structure of a masking member used in the electrolytic processing apparatus shown in FIGS. 1 and 2.

FIG. 4 is an external explanatory view of an essential part of the apparatus showing a usage state of the electrolytic processing apparatus shown in FIGS. 1 to 3.

5 is a diagram showing an example of an energized state in the electrolytic processing apparatus shown in FIGS. 1 to 4. FIG.

6 is a diagram showing another example of the energized state in the electrolytic processing apparatus shown in FIGS. 1 to 4. FIG.

FIG. 7 is a diagram showing a relationship between a submerged positioning depth in an electrolytic solution and electrolytic processing depth during electrolytic processing.

FIG. 8 is a longitudinal cross-sectional explanatory view showing a structural example of a hard disk drive motor (HDD) as an example of a device having a dynamic pressure bearing device manufactured by electrolytic processing according to the present invention.

9 is a bottom view showing a structural example of a thrust plate used in the dynamic pressure bearing device shown in FIG.

10 is an explanatory plan view showing a structural example of a thrust plate used in the dynamic pressure bearing device shown in FIG.

FIG. 11 is a vertical cross-sectional explanatory view of the thrust plate shown in FIGS. 9 and 10.

FIG. 12 is a front cross-sectional explanatory view showing a schematic structure of another embodiment of the electrolytic processing apparatus according to the present invention.

13 is a side cross-sectional explanatory view showing a schematic structure of the electrolytic processing apparatus shown in FIG.

FIG. 14 is an enlarged cross-sectional view of a main part of FIG. 13, and is a cross-sectional explanatory view corresponding to a position along line III-III in FIG. 15.

15 is an explanatory plan view showing a structure of a masking member used in the electrolytic processing apparatus shown in FIGS. 12, 13 and 14. FIG.

16 is an external view of the essential parts of the apparatus showing the usage state of the electrolytic processing apparatus shown in FIGS. 12 to 15. FIG.

FIG. 17 is a front sectional explanatory view showing a schematic structure of another embodiment of the electrolytic processing apparatus according to the present invention.

18 is a side cross-sectional explanatory view showing a schematic structure of the electrolytic processing apparatus shown in FIG.

FIG. 19 is a front explanatory view showing a pattern structure in the tip portion of the electrode tool used in the electrolytic processing apparatus shown in FIGS. 17 and 18.

20 is a cross-sectional explanatory view taken along the line IV-IV in FIG.

FIG. 21 is an external view of the essential parts of the apparatus showing the usage state of the electrolytic processing apparatus shown in FIGS. 17 to 20.

FIG. 22 is a schematic side view showing a schematic structure of an example of a general electrolytic processing apparatus.

[Explanation of symbols]

10 Stator set 20 rotor sets 21 rotation axis 22 rotating hub 23 Thrust plate 23a, 23b Thrust dynamic pressure generating groove 23 'Thrust plate material (workpiece) SBa, SBb thrust dynamic pressure bearing part 31 Base unit 32 Work support jig 33 Masking member 33a communication hole pattern 34 Cap-shaped member 35 electrode tool 35a liquid passage 37 shaker 41 Processing container 41a annular wall Pa Electrolytic Machining Pb Ultrasonic vibration energization Ca Electrolytic Machining Cb Ultrasonic vibration energization

Claims (11)

[Claims] 1. An electrode tool is arranged so as to oppose a work piece with a proper gap, and an appropriate electric current is applied between the work piece and the electrode tool while flowing an electrolytic solution in the gap. As a result, in the electrolytic machining method in which a recess having a desired shape is electrolytically machined with respect to the processed surface of the workpiece, the workpiece and the electrode tool are provided inside the machining accommodating portion that stores the electrolytic solution. And a position where the processed surface of the workpiece is machined at a depth of 5 mm to 35 mm from the liquid surface of the electrolytic solution stored in the processed accommodating portion. An electrolytic machining method is characterized in that the electrolytic solution is supplied so as to flow into a gap in a portion where the workpiece and the electrode tool face each other so as to perform electrolytic machining. 2. A material for a shaft member or a bearing member used in a dynamic pressure bearing device that utilizes dynamic pressure of a lubricating fluid is used as the workpiece, and a groove for dynamic pressure generation is formed in the workpiece as the concave portion. 2. The electrolytic processing method according to claim 1, wherein the electrolytic processing method is formed. 3. A masking member having a through-hole pattern corresponding to the shape of the recess penetratingly formed on the surface of the workpiece to be processed, and a gap between the masking member and the electrode tool. 2. The electrolytic processing is performed by supplying the electrolytic solution while flowing and causing the electrolytic solution to enter and flow inside the communication hole pattern in the masking member. Electrolytic processing method. 4. The electrolytic processing method according to claim 1, wherein a mixed solution with a surfactant is used as the electrolytic solution. 5. The electrolytic processing method according to claim 1, further comprising ultrasonic vibration generating means for applying ultrasonic vibration to the electrolytic solution. 6. A work supporting member for holding a work piece at an appropriate position, an electrode tool arranged to face the work piece with an appropriate gap, and an electrolyte solution flowing in the gap while the electrolytic solution is flowing. In an electrolytic processing apparatus, which is provided with an electric current processing means for performing an appropriate electric current between a workpiece and an electrode tool, and which is configured to electrolytically process a recess having a desired shape with respect to the processed surface of the workpiece. A work accommodating portion that stores the electrolytic solution and accommodates at least a facing arrangement portion of the workpiece and the electrode tool so as to be embedded in the electrolytic solution, wherein the work support member is in the processing accommodating portion. The electrolytic processing apparatus is configured to position the processing surface of the workpiece at a depth of 5 mm to 35 mm from the liquid surface of the electrolytic solution stored in. 7. The workpiece is a material of a shaft member or a bearing member used in a dynamic pressure bearing device using dynamic pressure of a lubricating fluid, and the recess is a dynamic pressure generating groove. The electrolytic processing apparatus according to claim 6. 8. A masking member having a through-hole pattern corresponding to the shape of the recess is formed in close contact with the surface of the workpiece to be processed, and a gap between the masking member and the electrode tool is provided. 7. The electrolytic processing is performed by supplying the electrolytic solution while flowing and causing the electrolytic solution to enter and flow inside the communication hole pattern in the masking member. Electrolytic processing equipment. 9. The electrolytic processing apparatus according to claim 6, wherein a mixed solution with a surfactant is used as the electrolytic solution. 10. The electrolytic processing apparatus according to claim 6, further comprising ultrasonic vibration generating means for applying ultrasonic vibration to the electrolytic solution. 11. The electrolytic processing apparatus according to claim 8, wherein an insulating member is provided on at least a surface portion of the masking member.