JP2002070869A - Pressed part and thrust plate of hydrodynamic bearing device, and method for manufacturing thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make possible avoidance satisfactorily of plastic deformation toward an internal circumferential wall surface 23h1 of a through-hole 23h provided in a pressed part such as thrust plate and the like with simple construction. SOLUTION: By providing a pressure relief part 23e having concave shaped inclined surfaces 23e1, 23e2 extending from opening fringe parts 23h2 at the outer side of the internal circumferential wall surface 23h1 of the through-hole 23h to inner circumference side edges 23a2, 23b2 of press-formed surfaces 23a, 23b, a press load applied to end faces 23a, 23b to be pressed is directed toward an axial direction and the internal circumferential wall surface 23h1 of the through-hole (shaft fixed hole) 23h is maintained in generally straight line shape in axial direction, by reducing volume of plastic deformation as usually occurred toward the radial direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thrust plate for a pressed part and a hydrodynamic bearing device in which both end surfaces of a main body portion having a through hole are formed by press forming, and a method of manufacturing the same.

[0002]

2. Description of the Related Art In general, various components are used in various fields in which a through-hole formed in a main body portion is inserted into a shaft-like member to join the two members together. For example, in a dynamic pressure bearing device in which a dynamic pressure is generated in a lubricating fluid to support a shaft member and a bearing member in a relatively rotatable manner, a shaft fixing hole (through hole) of a thrust plate constituting a thrust bearing portion. ) Is inserted into the shaft member by press-fitting or shrink-fitting. Then, at least one end surface of such a thrust plate is subjected to a press working such as coining, thereby forming a dynamic pressure surface composed of a press-formed surface, and a dynamic pressure generating surface for the dynamic pressure surface. A groove is provided to be recessed.

That is, the above-mentioned thrust plate is
For example, it has a ring-shaped disc-shaped main body portion 1 as shown in FIG. 10, and a shaft fixing hole 2 for inserting the shaft member side (not shown) in a central portion of the main body portion 1. It is formed to penetrate in the axial direction. Then, press working such as coining is performed on both end surfaces 1a and 1b in the axial direction of the main body portion 1, and the end surfaces 2a and 2b in the axial direction of the main body portion 1 are respectively pressed by the axial pressing force at that time. Are formed on the dynamic pressure surfaces, and at the same time, grooves (grooves) for generating dynamic pressure, such as herringbone shapes, are formed in both of the dynamic pressure surfaces.

[0004]

However, when a pressing load is applied in the axial direction to the main body portion 1 having the shaft fixing hole (through hole) 2 such as the above-described thrust plate, for example, FIG. As shown, the inner peripheral wall surface 2a of the shaft fixing hole (through hole) 2 may be plastically deformed so as to be concave in a barrel shape. Such barrel-shaped plastic deformation of the inner peripheral wall surface 2a is caused by the axial end surfaces 1a, 1 of the main body portion 1.
This is considered to be due to the fact that the meat portion located in the vicinity of b protrudes inward in the radial direction due to plastic flow in the radially inward and outward directions due to the above-described press load.

If the shaft fixing hole (through hole) 2 which has been plastically deformed into such an irregular shape is mounted on the shaft member side without taking any measures, the shaft fixing hole (through hole) will be removed. The inner peripheral wall surface 2a of the hole 2) and the outer peripheral wall surface side of the shaft member do not sufficiently adhere to each other, so that a gap is generated between the two members. As a result, necessary bonding strength and surface pressure are obtained. And the joint strength between the two members may be significantly reduced.

In particular, in the case of a thrust plate used in a dynamic pressure bearing device, it is necessary to attach the thrust plate with high accuracy in order to generate dynamic pressure, and it is also sufficient to prevent external impact and the like. It is required that the shaft member be fixed to the shaft member with bonding strength. Therefore,
The reliability of the above-described thrust plate joint is an important problem in putting the dynamic bearing device into practical use.

[0007] Incidentally, in those already proposed in JP-A-6-315241 and JP-A-7-296502, a pressing step is performed on a thrust plate previously inserted in a loosely fitted state on the shaft member side. According to the pressing force at that time, the process of forming the dynamic pressure generating groove (groove) and the process of fixing the thrust plate to the shaft member side are simultaneously performed. There is a problem that sufficient bonding strength cannot be obtained.

Accordingly, the present invention is capable of satisfactorily avoiding plastic deformation of through-holes provided in various press parts such as thrust plates with a simple configuration, and obtaining good joint strength. An object of the present invention is to provide a thrust plate for a pressed part and a hydrodynamic bearing device, and a method for manufacturing the same.

[0009]

According to a first aspect of the present invention, at least one end face is formed of a press-formed surface pressed by a corresponding punch. A pressed part provided with a through-hole so as to penetrate from the forming surface, and having a radially inner peripheral portion of the press-formed surface formed along the opening peripheral portion on the axially outer end side of the through-hole. In the portion between the peripheral edge of the opening on the axially outer end side of the through-hole and the peripheral edge on the radially inner peripheral side of the press-formed surface, the inner diameter of the through-hole is directed outward in the axial direction. A pressure relief portion having an inclined surface extending so as to gradually enlarge the pressure relief portion, wherein the inclined surface of the pressure relief portion is formed by an opening peripheral portion on an axially outer end side of the through hole, and the press-formed surface. To the radially inner peripheral edge of the It is formed so as to be recessed in a concave shape from the reference plane.

In the thrust plate of the dynamic pressure bearing device according to the second aspect, a dynamic pressure surface formed by a press-formed surface pressed by a corresponding punch is provided on at least one end surface of the thrust dynamic pressure bearing. With
A shaft fixing hole through which the shaft member is inserted is formed so as to penetrate from the dynamic pressure surface formed of the press-formed surface, and along the opening peripheral edge of the shaft fixed hole on the axially outer end side, from the press-formed surface. In the thrust plate of the hydrodynamic bearing device in which the radially inner peripheral edge of the dynamic pressure surface is formed, the opening peripheral edge of the shaft fixing hole on the axial outer end side and the dynamic pressure surface formed of the press-formed surface are formed. A pressure relief portion having an inclined surface extending so as to gradually increase the inner diameter of the shaft fixing hole toward the outer side in the axial direction is provided at a portion between the inner peripheral side and the peripheral portion on the radially inner side. The inclined surface of the pressure relief portion is a reference that linearly connects an opening peripheral portion of the shaft fixing hole on an axially outer end side and a radially inner peripheral portion of a dynamic pressure surface formed of the press-formed surface. It is formed so as to be recessed from the surface.

Further, in the thrust plate of the pressed part and the dynamic pressure bearing device according to the third aspect, the inclined surface of the pressure relief portion according to the first or second aspect is such that two linear inclined surfaces are discontinuous. And is formed so as to form a step shape.

Further, in the thrust plate of the pressed part and the dynamic bearing device according to the fourth aspect, the first aspect.
Alternatively, the inclined surface of the pressure relief portion according to claim 2 is formed from one curved surface.

[0013] On the other hand, in the method for manufacturing a pressed part according to the fifth aspect, the outer peripheral wall surface of the blank material having the through hole formed therein is held by an outer diameter press, and the inside of the through hole is formed inside the through hole. The inner diameter retainer is inserted so as to be able to contact the peripheral wall surface, and a pair of punches are arranged so as to face each other across the blank material, and at least one end surface of the blank material is subjected to the pair of punches. In a method of manufacturing a pressed part formed on a desired press-formed surface, a portion between an opening peripheral portion of the through-hole on an axially outer end side and a radially inner peripheral portion of the press-formed surface is formed. A pressure relief portion having an inclined surface extending so as to gradually increase the inner diameter of the through hole toward the outside in the axial direction, and the inclined surface of the pressure relief portion is Open the outer end of the hole in the axial direction. The peripheral portion and the peripheral portion on the radially inner side of the press forming surface are formed so as to be depressed in a concave shape from a reference surface that linearly connects the press forming surface, so that the direction of the plastic flow due to the press load is reduced by the pressure relief portion. The inner peripheral wall surface of the through hole is formed so as to extend substantially linearly along the axial direction so as to extend toward the axial direction along the inclined surface.

In the method for manufacturing a thrust plate of a dynamic pressure bearing device according to a sixth aspect of the present invention, the outer peripheral wall surface of the blank material having a shaft fixing hole formed through the shaft member is held by an outer diameter press, and In the shaft fixing hole, an inner diameter retainer is inserted so as to be able to contact the inner peripheral wall surface of the shaft fixing hole, and a pair of punches are arranged on both sides of the blank material so as to face each other, In a method for manufacturing a thrust plate press of a dynamic pressure bearing device in which at least one end surface of the blank material is formed into a dynamic pressure surface formed of a press-formed surface by the pair of punches, an axial outer end side of the shaft fixing hole is provided. The inner diameter of the shaft fixing hole is gradually enlarged toward the outer side in the axial direction at a portion between the opening peripheral portion and the radially inner peripheral portion of the dynamic pressure surface formed of the press-formed surface. A pressure relief portion having an inclined surface extending in a manner as described above is provided, and the inclined surface of the pressure relief portion is formed by a pressurized surface formed by the axially outer end of the shaft fixing hole and the press forming surface. By forming it so as to be depressed concavely from the reference surface that linearly connects the radially inner peripheral side of the pressure surface to the peripheral portion, the direction of plastic flow due to the press load can be changed in the axial direction along the inclined surface of the pressure relief portion. The inner peripheral wall surface of the shaft fixing hole is formed so as to extend substantially linearly along the axial direction.

Furthermore, in the method for manufacturing a pressed part or the method for manufacturing a thrust plate of a dynamic pressure bearing device according to claim 7, the inclined surface of the pressure relief portion according to claim 5 or 6 is formed by two straight lines. The slopes are discontinuously connected to form a step shape.

Further, in the method for manufacturing a pressed part or the method for manufacturing a thrust plate of a dynamic pressure bearing device according to the eighth aspect, the inclined surface of the pressure relief portion according to the fifth or sixth aspect may be formed by bending one side. It is formed from the surface.

According to the pressed part of the first aspect or the thrust plate of the hydrodynamic bearing device according to the second aspect, an appropriate press load is applied to the end face to be press-formed. At this time, among the meat portions located in the vicinity of the end face to be press-formed, particularly the opening of the through hole (shaft fixing hole) plastically flows toward the axial direction along the inclined surface of the pressure relief portion. As a result, the amount of plastic deformation in the radial direction as in the related art is reduced, and the amount of deformation of the inner peripheral wall surface of the through hole (shaft fixing hole) is greatly reduced. As a result, the inner peripheral wall surface of the through hole (shaft fixing hole) is maintained almost in the original state of being linear in the axial direction.

Further, claim 3 or claim 4 or claim 7
Alternatively, according to the thrust plate of the pressed component or the dynamic pressure bearing device according to claim 8, the inclined surface of the pressure relief portion is formed in an easy-to-machine shape such as two linear inclined surfaces or one curved surface. This enables efficient production.

Further, according to the method for manufacturing a pressed part according to claim 5 or the method for manufacturing a thrust plate of a dynamic pressure bearing device according to claim 6, the pressed part according to claim 1 or the claim 2 described above. The thrust plate of the hydrodynamic bearing device is easily and efficiently formed.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment in which the present invention is applied to a bearing member of a hard disk drive (HDD) will be described. First, the overall structure of the hard disk drive (HDD) will be described with reference to the drawings. I do.

The entire spindle rotating HDD spindle motor shown in FIG. 1 is composed of a stator set 1 as a fixing member.
And a rotor set 2 as a rotating member mounted on the stator set 1 from above.
The stator set 1 has a fixed frame 11 screwed to a fixed base (not shown). The fixed frame 11 is formed of an aluminum-based metal material to reduce the weight. The bearing holder 1 having an annular cylindrical body is provided at a substantially central portion of the fixed frame 11.
2 are integrally formed so as to be erected.

On the inner peripheral wall side of the bearing holder 12,
A bearing sleeve 13 as a fixed bearing member formed in a hollow cylindrical shape is inserted, and is fixed by an adhesive (not shown). The bearing sleeve 13 can be joined to the bearing holder 12 by press fitting or shrink fitting. Such a bearing sleeve 13
Is made of a copper-based alloy material such as phosphor bronze in order to facilitate processing of small-diameter bearing holes.

A stator core 14 made of a laminated body of electromagnetic steel sheets is fitted on a mounting surface provided on the outer peripheral side wall surface of the bearing holder 12. This stator core 1
A drive coil 15 is wound around each salient pole portion provided in 4.

Further, a rotating shaft 21 constituting the above-mentioned rotor set 2 is rotatably inserted into a bearing hole formed through the bearing sleeve 13 along the central axis.
The rotating shaft 21 in the present embodiment is formed from stainless steel.

The dynamic pressure surface formed on the inner peripheral surface of the bearing hole in the bearing sleeve 13 is disposed so as to face the dynamic pressure surface formed on the outer peripheral surface of the rotary shaft 21 in the radial direction. In addition, a radial dynamic pressure bearing portion RB is formed in a minute bearing gap space between the two dynamic pressure surfaces. More specifically, the radial dynamic pressure bearing portion RB
The dynamic pressure surface on the bearing sleeve 13 side and the dynamic pressure surface on the rotating shaft 21 side are circumferentially opposed to each other with a small gap of about several μm. A predetermined lubricating fluid, such as oil or magnetic fluid, is injected.

Further, on the dynamic pressure surface on the bearing sleeve 13 side, a radial dynamic pressure generating groove having a shape such as a herringbone shape (not shown) is annularly recessed, for example, divided into two blocks in the axial direction. During rotation, the lubricating fluid is pressurized by the pumping action of the two radial dynamic pressure generating grooves to generate a dynamic pressure, and the dynamic pressure of the lubricating fluid causes the rotating shaft 22 to be described later together with the rotating shaft 21.
Are supported by the shaft while floating in the radial direction.

On the other hand, a lower end of the rotary shaft 21 in the figure is provided with a ring-shaped thrust plate 23, for example, as also shown in FIGS.
Is fixed. A shaft fixing hole 23h is formed in the center of the thrust plate 23 so as to penetrate in the axial direction. The shaft fixing hole 23h is inserted into the outside of the rotary shaft 21 by press-fitting or baking. Joined by shrink. The thrust plate 23 and the rotating shaft 21
Will be described later.

The thrust plate 23 joined to the rotating shaft 21 is disposed so as to be accommodated in a cylindrical recess formed in the center portion of the bearing sleeve 13 at the lower end in the figure. In the recess of the bearing sleeve 13, the thrust plate 23
The dynamic pressure surface 23a provided on the upper surface side of the drawing is opposed to the dynamic pressure surface on the bearing sleeve 13 side so as to approach in the axial direction. A thrust dynamic pressure bearing portion SBa on the upper side in the figure is formed in a bearing gap space between the dynamic pressure surfaces of the thrust plate 23 and the bearing sleeve 13.

Further, a counter plate 16 made of a relatively large-diameter disc-shaped member is arranged near the dynamic pressure surface 23b on the lower side of the thrust plate 23 in the figure. The counter plate 16 is mounted so as to close the lower end side opening portion of the bearing sleeve 13 and fixed by an adhesive, and has a dynamic pressure surface provided on the upper surface side of the counter plate 16 in the drawing, The illustrated dynamic pressure surface 23b of the thrust plate 23 described above
A thrust dynamic pressure bearing portion SBb on the lower side in the figure is formed in the proximity facing gap portion between the two.

As described above, in the pair of thrust dynamic pressure bearing portions SBa, SBb disposed adjacent to each other in the axial direction, the two dynamic pressure surfaces 23a, 23b on the thrust plate 23 side.
The bearing sleeve 13 and the two dynamic pressure surfaces on the counter plate 16 side facing each other are axially opposed to each other with a micro gap of several μm therebetween, and are placed in a bearing gap space formed by the micro gap. Are filled with the same lubricating fluid so as to be continuous from the above-described radial dynamic pressure bearing portion RB, and the lubricating fluid is made to continue in the axial direction through the outer peripheral side passage of the thrust plate 23. I have.

Further, at least one of the dynamic pressure surfaces 23a and 23b of the thrust plate 23 and the dynamic pressure surfaces of the bearing sleeve 13 and the counter plate 16 are provided, for example, as shown in FIGS. The dynamic pressure generating grooves 23c and 23d having a herringbone shape are annularly recessed, and the lubricating fluid is pressurized by the pumping action of the thrust dynamic pressure generating grooves 23c and 23d during rotation to generate dynamic pressure. The rotating shaft 21 and the rotating hub 22 described above are axially supported in the thrust direction by the dynamic pressure of the lubricating fluid.

At this time, the above-described thrust plate 23
The inner peripheral wall surface 23h1 of the shaft fixing hole 23h is formed into a substantially linear wall surface along the axial direction by being formed by a manufacturing apparatus and a manufacturing method described later. In order to obtain such a linear inner peripheral wall surface 23h1, in the present embodiment, pressure relief portions 23 are provided at both ends in the axial direction (vertical direction in FIG. 3) of the shaft fixing hole 23h.
e and 23e are provided respectively. More specifically,
Each of the pressure relief portions 23e is formed from an opening peripheral portion 23h2 provided at each end of the shaft fixing hole 23h in the axial direction (vertical direction in FIG. 3), and at each of the inner peripheral edges of the both dynamic pressure surfaces 23a and 23b. It is provided over a portion between the portions 23a2 and 23b2.

That is, as shown in FIGS. 3 and 7, each of the pressure relief portions 23e is provided with the shaft fixing hole 2e.
3h, the shape is continuously formed so as to be concave in a stepwise manner toward the outside in the axial direction, and the inner diameter of the shaft fixing hole 23h is gradually increased toward the outside in the axial direction. Linearly inclined surfaces 23e1, 23e2 extending to
It is composed of And both straight slopes 2
Among the 3e1 and 23e2, the one-side linear inclined surface 23e1 extending from the shaft fixing hole 23h side extends substantially radially outward and forms a substantially planar shape. The linear inclined surface 23e2 on the other side extending from each of the dynamic pressure surfaces 23a and 23b,
It extends from the outer side in the axial direction to the inner side so as to form an angle of 45 ° or more with the axial direction. These two linear inclined surfaces 23e1 and 23e2 are discontinuously connected so as to abut each other at their extending end portions, and as a result, as described above, the pressure relief portion 23e
Are formed in a stepped shape.

As described above, each of the pressure relief portions 23e formed by the above-described two linear inclined surfaces 23e1 and 23e2 is provided with an opening provided at both axial ends (outward side) of the shaft fixing hole 23h. The peripheral edge 23h2 and the inner peripheral edges 23a2 and 23b2 of the two dynamic pressure surfaces 23a and 23b are
It is formed in a concave shape with respect to a linearly connected reference plane.

Returning to FIG. 1, the rotary hub 22 which forms the rotor set 2 together with the rotary shaft 21 is made of aluminum-based metal or iron such that a recording medium disk such as a magnetic disk not shown is mounted. A joining hole provided at a central portion of the rotary hub 22 is integrally joined to the upper end portion of the rotating shaft 21 by press fitting or shrink fitting. . The rotary hub 22 has a substantially cylindrical body 22a on which a recording medium disk is mounted on an outer peripheral portion, and a disk mount provided so as to project radially outward from the body 22a. The recording medium disk (not shown) is placed on the surface 22b.

On the inner peripheral wall side of the body 22a,
An annular drive magnet 25 is attached via an annular magnetic yoke 24. The annular drive magnet 25 is arranged in proximity to the outer peripheral end face of the salient pole portion of the stator core 14 so as to annularly face the above.

Next, an embodiment of a method for manufacturing the above-described thrust plate 23 will be described together with a manufacturing apparatus. FIG.
As shown in FIG. 3, a blank (hereinafter, simply referred to as a blank) 23 'of the thrust plate 23 passes through the prepared hole (hereinafter, simply referred to as a prepared hole) 23h' of the shaft fixing hole 23h. Formed, and the blank material 23 ′ is placed at an appropriate position on the lower punch 31,
The outer peripheral wall surface of the blank material 23 ′ is held by the outer diameter retainer 32. Also, a center pin 33 as an inner diameter holding member is inserted into the inner side of the lower hole 23h ', and the inner peripheral wall surface of the lower hole 23h' is arranged so as to be able to contact the outer peripheral wall side of the center pin 33. Keep it.

From such a holding state, the lower punch 3
Upper punch 34 arranged so as to face the upper side of 1.
Is lowered toward the blank material 23 ′, thereby performing coining. At this time, the above-mentioned herringbone-shaped dynamic pressure generating grooves 23c and 23d are formed on the press working surfaces of the lower punch 31 and the upper punch 34, respectively.
A shape corresponding to the negative shape of FIG. 2 (see FIGS. 2 and 4) is provided in a convex shape, and the blank material 2 is pressed by pressing force between the upper and lower punches 31, 34.
At the same time as the dynamic pressure surfaces are formed on both end surfaces in the axial direction of 3 ′, the above-described dynamic pressure generating grooves 23c and 23d are recessed.

By such a coining process,
When an appropriate pressing load is applied to the axial end face of the blank material 23 'in the axial direction, particularly the lower hole 23h' of the portion located near the axial end face of the blank material 23 '. The meat portion forming the opening is formed by the inclined surface 23 on the other side of each pressure relief portion 23e described above.
plastic flow toward the axial direction along e2,
A conventional plastic deformation amount in the radial direction is reduced. Therefore, the amount of deformation of the inner wall surface of the pilot hole 23h 'is significantly reduced, and as a result, the inner wall surface 23h1' of the pilot hole 23h 'before the coining shown in FIG.
In FIG. 7, the original state of forming a straight line in the axial direction is maintained almost straight on the inner peripheral wall surface 23h1 after coining in FIG.

The thrust plate 24 in the present embodiment has a thickness of 0.8 mm in the axial direction at the stage of the blank material before the coining process.
0.03m in the axial direction by the above coining process
m is crushed. In the present embodiment, the axial length of the pressure relief portion 24e is set to 0.1 mm, and the radial length of the pressure relief portion 24e is set to 0.2 mm. .

And actually, in such an axial direction, 0.8
When the blanking material 23 'of the thrust plate 23 having a thickness of 3 mm was subjected to coining processing and the amount of deformation at that time was measured, the conventional product had a barrel-shaped cross section as shown in FIG. It is transformed into a shape,
A dent amount of about 2 μm was measured at the maximum dent portion at the central portion in the axial direction (lateral direction in the drawing). On the contrary,
In the case where the present invention is applied, as shown in FIG. 9, in the central portion in the axial direction (horizontal direction in the drawing), the amount of depression is suppressed to a maximum of about 0.2 μm or less, and the amount of deformation is greatly reduced. It turned out to be.

A thrust plate 23 having a shaft fixing hole 23h maintained linearly in the axial direction.
Is joined to the rotating shaft 21 by press-fitting or shrink-fitting, so that the inner peripheral wall surface 23h1 which is linear in the axial direction of the shaft fixing hole 23h is good with respect to the outer peripheral wall surface of the rotating shaft 21 without any gap. As a result, a strong surface pressure is obtained, and the two members 23 and 21 are fixed to each other with a large bonding strength.

Also, such a thrust plate 23
Is easily and efficiently formed by the manufacturing method according to the present invention using the manufacturing apparatus shown in FIG.
The pressure relief portion 23e has two simple linear inclined surfaces 23e.
Since it is composed of 1, 23e2, it can be easily molded.

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

For example, in the above-described embodiment, the pressure relief portion 23e is constituted by the two linear inclined surfaces 23e1 and 23e2, but the present invention is not limited to this. It can be easily formed by a curved surface or the like.

Further, the present invention provides various kinds of dynamic pressure bearing motors such as a dynamic pressure bearing device used for a motor for rotating a polygon mirror other than the above-described hard disk drive (HDD) motor, and others. The present invention can be similarly applied to various press parts employed in various devices.

[0047]

As described above, the thrust plate of the pressed part or the hydrodynamic bearing device according to the present invention and the method of manufacturing the same are provided by the press forming surface from the outer end of the inner peripheral wall surface of the through hole (shaft fixing hole). By providing a pressure relief portion having a concave inclined surface toward the inner peripheral side of the hole, the press load applied to the end face to be press-formed is directed toward the axial direction, and the inner periphery of the through hole (shaft fixing hole) is formed. Since the wall surface is maintained to be substantially linear in the axial direction, it is possible to prevent plastic deformation of the inner peripheral wall surface of the through hole provided in various pressed parts such as the thrust plate, and the dynamic pressure bearing device. Increases the bonding strength when inserting and fixing through holes (shaft fixing holes) of pressed parts such as thrust plates to other parts, and improves the accuracy and reliability of the bonded parts of the pressed parts with a simple configuration Greatly improved by It can be.

Further, the thrust plate of the pressed part or the hydrodynamic bearing device according to the present invention and the method of manufacturing the same are characterized in that the inclined surface of the pressure relief portion is constituted by two linear inclined surfaces or one curved surface. Since it is possible to form easily, productivity can be further improved in addition to the above-mentioned effects.

[Brief description of the drawings]

FIG. 1 shows an HDD provided with a hydrodynamic bearing device to which the present invention is applied.
FIG. 3 is an explanatory longitudinal sectional view showing a structural example of a motor for a (hard disk drive).

FIG. 2 is an explanatory plan view showing a structural example of a thrust plate used in a dynamic pressure bearing device of the HDD (hard disk drive) motor shown in FIG. 1;

FIG. 3 is an explanatory longitudinal sectional view of the thrust plate shown in FIG. 2;

FIG. 4 is an explanatory bottom view of the thrust plate shown in FIG. 2;

5 is an explanatory longitudinal sectional view showing an example of a press device for performing a press (coining) process on a blank material of a thrust plate shown in FIG. 2;

6 is an explanatory longitudinal sectional view showing a structure of a blank material before press (coining) processing of the thrust plate shown in FIG. 2;

FIG. 7 is an explanatory longitudinal sectional view showing a blank material after press (coining) processing.

FIG. 8 is a diagram showing a state of an inner peripheral wall surface of a shaft fixing hole (through hole) after pressing (coining) processing of a conventional thrust plate.

FIG. 9 is a diagram showing a state of an inner peripheral wall surface of a shaft fixing hole (through hole) after pressing (coining) processing of a thrust plate according to the present invention.

FIG. 10 is an explanatory longitudinal sectional view showing a structure of a blank material before press (coining) processing of a conventional thrust plate.

FIG. 11 is an explanatory longitudinal sectional view showing a blank material after a conventional press (coining) process.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 13 Bearing sleeve 16 Counter plate SBa, SBb Thrust dynamic pressure bearing part 21 Rotary shaft 23 Thrust plate 23a, 23b Dynamic pressure surface 23a2, 23b2 Inner peripheral part 23c, 23d Dynamic pressure generating groove 23e Pressure relief part 23h Shaft fixing hole 23h1 Inner peripheral wall surface 23h2 Outer end side opening peripheral edge 23e1, 23e2 Inclined surface 23 'Thrust plate blank material 23h' Shaft fixing hole lower hole 23h1 'Inner peripheral wall surface 31 Lower punch 32 Outer diameter holder 33 Center pin (inner diameter holder) 34 Upper punch

Continued on the front page (72) Inventor Hiroshi Kenzawa 5329 Shimosuwa-cho, Suwa-gun, Nagano F-term in Sankyo Seiki Seisakusho Co., Ltd. (reference) 3J011 BA08 CA02 DA02 KA03 SB03

Claims (8)

[Claims] At least one end surface is formed of a press-formed surface pressed by a corresponding punch, and a through-hole is provided so as to penetrate from the press-formed surface. In a pressed part having a peripheral portion on an inner peripheral side in the radial direction of the press forming surface formed along an opening peripheral portion on an end side, an opening peripheral portion on an axially outer end side of the through hole, and the press forming surface A pressure relief portion having an inclined surface extending so as to gradually increase the inner diameter of the through hole toward the outer side in the axial direction is provided in a portion between the inner peripheral portion and the peripheral portion on the radially inner peripheral side. The inclined surface of the pressure relief portion is concavely recessed from a reference surface that linearly connects an opening peripheral portion on the axially outer end side of the through hole and a radially inner peripheral portion of the press-formed surface. A stamped part characterized by being formed in such a way. 2. A thrust hydrodynamic bearing, wherein at least one end face of the thrust hydrodynamic bearing is provided with a hydrodynamic surface formed by a press-formed surface pressed by a corresponding punch, and the shaft fixing hole through which a shaft member is inserted is provided. Aperipheral portion of the dynamic pressure surface formed of the press-formed surface is formed so as to penetrate from the dynamic pressure surface formed of the press-formed surface, along the opening peripheral portion of the shaft fixing hole on the outer end side in the radial direction. In the thrust plate of the dynamic pressure bearing device, a portion between an opening peripheral edge of the shaft fixing hole on the axial outer end side and a radial inner peripheral side of the dynamic pressure surface formed of the press-formed surface is formed. A pressure relief portion provided with an inclined surface extending so as to gradually increase the inner diameter of the shaft fixing hole toward the outside in the axial direction, and the inclined surface of the pressure relief portion is provided on the shaft. Opening the outer end of the fixing hole in the axial direction A thrust of a hydrodynamic bearing device characterized in that it is formed so as to be depressed in a concave form from a reference surface that linearly connects an outer peripheral portion and a peripheral portion on the radially inner side of the dynamic pressure surface formed of the press-formed surface. plate. 3. The pressed part according to claim 1, wherein the inclined surface of the pressure relief portion is formed so that two linear inclined surfaces are discontinuously connected to form a step shape. A thrust plate for a hydrodynamic bearing device according to claim 2. 4. The thrust plate according to claim 1, wherein the inclined surface of the pressure relief portion is formed from a single curved surface. 5. An outer peripheral wall of a blank material having a through hole formed therein is held by an outer diameter retainer, and an inner diameter retainer is held in the through hole so as to be able to contact the inner peripheral wall surface of the through hole. A press in which a pair of punches are arranged so as to face each other with the blank material interposed therebetween so that at least one end surface of the blank material is formed into a desired press-formed surface by the pair of punches. In the method of manufacturing a part, the inner diameter of the through hole is set to be outside of the axial direction at a portion between an opening peripheral edge of the through hole in the axially outer end side and a radially inner peripheral side of the press forming surface. A pressure relief portion having an inclined surface extending so as to gradually expand toward one side is provided, and the inclined surface of the pressure relief portion is formed with an opening peripheral portion on an axially outer end side of the through hole. , Radially inner peripheral side of the press forming surface By forming it so as to be concavely depressed from the reference plane that linearly connects the peripheral edge of the pressure relief portion, the direction of the plastic flow caused by the press load is directed axially along the inclined surface of the pressure relief portion. A method for manufacturing a pressed part, wherein an inner peripheral wall surface of a through hole is formed to extend substantially linearly along an axial direction. 6. The outer peripheral wall surface of a blank material, through which a shaft fixing hole through which a shaft member is inserted is formed, is held by an outer diameter press, and the inner peripheral wall surface of the shaft fixing hole is brought into contact with the inside of the shaft fixing hole. Insert the inner diameter press so that it becomes possible, arrange a pair of punches on both sides across the blank material, at least one end face of the blank material from the press forming surface by the pair of punches A method of manufacturing a thrust plate press of a dynamic pressure bearing device, which is formed on a dynamic pressure surface, comprising: an opening peripheral portion on an axially outer end side of the shaft fixing hole; A pressure relief portion having an inclined surface extending so as to gradually increase the inner diameter of the shaft fixing hole toward the outside in the axial direction is provided in a portion between the peripheral portion and the peripheral portion, Pressure relief The inclined surface of the shank is concave from a reference surface that linearly connects the opening peripheral edge of the shaft fixing hole on the axial outer end side and the radial inner peripheral side of the dynamic pressure surface formed of the press-formed surface. The direction of the plastic flow caused by the press load is directed toward the axial direction along the inclined surface of the pressure relief portion, and the inner peripheral wall surface of the shaft fixing hole is formed along the axial direction. A method of manufacturing a thrust plate press for a hydrodynamic bearing device, wherein the thrust plate press is formed so as to extend substantially linearly. 7. The manufacturing of a pressed part according to claim 5, wherein the inclined surface of the pressure relief portion is formed stepwise by discontinuously connecting two linear inclined surfaces. A method of manufacturing a thrust plate for a dynamic pressure bearing device according to claim 6. 8. The method for manufacturing a pressed part according to claim 5, wherein the inclined surface of the pressure relief portion is formed from one curved surface, or the dynamic pressure bearing device according to claim 6. Thrust plate manufacturing method.