CN1083070C

CN1083070C - Grooved hydrodynamic thrust bearing

Info

Publication number: CN1083070C
Application number: CN96199566A
Authority: CN
Inventors: M·M·拉曼; H·利约索尔德; W·克拉克
Original assignee: Seagate Technology LLC
Current assignee: Seagate Technology LLC
Priority date: 1996-01-08
Filing date: 1996-10-08
Publication date: 2002-04-17
Anticipated expiration: 2016-10-08
Also published as: JP2000503101A; WO1997025543A1; GB2323133A; KR19990076767A; GB2323133B; DE19681719T1; GB9810766D0; CN1207797A; JP3461357B2; KR100343273B1; HK1015857A1

Abstract

Two thrust bearing surfaces are separated by bearing fluid and are rotatable relative to one another. One of the bearing surfaces defines a plurality of continuous lands (122) extending from an inner (124) to an outer radius (126) of the bearing surface. Adjacent lands define between them a continuous groove (128) which has an undivided portion (130) in an inner annulus and a divided portion (132) in an outer annulus of the bearing surface. The continuous groove is divided in the divided portion (132) by an intermediate land (134) located between the adjacent continuous lands (122). The divided portion (132) of the continuous groove (128) communicates in unbroken fashion with the undivided portion (130).

Description

The hydrodynamic thrust bearing of trough of belt

Technical field

The present invention relates to be used for a kind of hydrodynamic thrust bearings of mandrel motor.More particularly, the present invention relates to be used for the shape of groove of the hydrodynamic thrust bearings of computer hard drive mandrel electric machine assembly.

Technical background of the present invention

Computer hard disc driver generally includes one and arranges the disk that is installed on the mandrel electric machine assembly.By the read/write head on the end that is located at an arm that extends between these disks data are write on each disk or from disk and to read.The location of this arm is to realize by a voice coil motor under the control of dish drive controlling electronics.

This row's disk is installed on one of mandrel electric machine assembly turns.This is turned and is mounted to and can rotates with respect to a substrate of mandrel motor by means of a bearing means.In use, make the rotation of turning by an electromagnetic machine.

For the ease of the accurate localization of read/write head between disk, need bearing means essentially no vibration of when operation, and deflection very little (, rigidity of support height) when applying external force.Also wish the long service life of bearing means, and need not keep in repair.The tendency of the continuous miniaturization of computer industry means that above-mentioned functions must realize with the bearing means that occupies as far as possible little volume.

The bearing means that is used for computer disks driving mandrel electric machine assembly is generally fluid bearing unit, and it comprises at least one hydrodynamic thrust bearings.Thrust bearing comprises a push pedal and an opposite only plate, and they limit a stayed surface separately.Each bearing surface is formed by a kind of groove.In use, the diaxon bearing surface is separated by one deck lubricant film.Pressure in the oiling agent that produces owing to the relative rotation of bearing surface makes bearing surface keep separating and guaranteeing the level and smooth rotation of bearing means.

Quiet or the dynamic response of other of axial load support force and thrust bearing depends on that the pressure in the lubricant film rises and across the pressure distribution of thrust bearing.And the design of the pattern of slotting is depended in pressure rising and distribution, for example pitch of the angle of groove, groove ratio, groove depth and push pedal or the only center radius of plate.

Existing thrust bearing is conceived to make the maximizing performance of bearing when designing.The raising of this performance is that manufacture difficulty with the bearing surface that increases trough of belt is a cost.Particularly, the density of groove and shape cause being used to form the reduction in the working life of the drift of pattern of groove and die assembly.

Therefore, need a kind of grooved, it provides the thrust bearing performance of good limit, and can not play negative effect to the manufacturing of thrust bearing.

General introduction of the present invention

The invention provides a kind of hydrodynamic thrust bearings that comprises the fluting of first and second bearing surfaces.This first and second bearing surface can rotate relative to one another, and is separated by a kind of bearing fluid.The clutch shaft bearing face limit a plurality of in one the continuous intercolpium that extends of an external diameter radially.Adjacent continuous intercolpium limits the continuous groove between them, and this groove has a roughly constant degree of depth and extends between internal diameter and external diameter in continual mode.This continuous groove the clutch shaft bearing face one in have a unallocated part in the ring, a part of dividing is arranged in an outer shroud of clutch shaft bearing face, and in the part of this division by middle an intercolpium division between two adjacent continuous intercolpiums.The division of continuous groove part is communicated with the unallocated part of continuous groove in continual mode.Each comprises that with intercolpium first leg and that is positioned at outer shroud is positioned at second leg of ring continuously, and first and second leg intersects at a center radius place and also constitutes angle each other.

The present invention also proposes a kind of bearing means that comprises the hydrodynamic thrust bearings of fluting, and it comprises:

One axle journal, it limits a journal hole, also limits an axle journal that extends perpendicular to journal hole and pushes away face; One is installed in the axle in the journal hole, and this axle and journal hole limit filmatic bearing together, and this bearing allows axle and axle journal to rotate relative to one another; One laterally leaves axle extends and limits first and second push pedals that push away face, and first pushes away face pushes away face with axle journal and limit a first fluid power thrust bearing; And one be installed on the axle journal and limit one and end the plate that ends that plate pushes away face, ending plate pushes away face and pushes away face with second and limit one second hydrodynamic thrust bearings, in first and second hydrodynamic thrust bearings at least one pushes away the push away face of face for fluting, its limit a plurality of from fluting push away face one in radially fluting push away the continuous intercolpium that an external diameter of face extends, between them, limit a continuous groove between adjacent continuous groove, this groove extends between internal diameter and external diameter in continual mode, and has a degree of depth of a constant, continuous groove is included in an interior unallocated part and the stroke portions in an external diameter of the face that pushes away of slotting of an internal diameter of the face that pushes away of fluting, continuous groove is divided by the middle intercolpium between adjacent continuous intercolpium in dividing part, the division of continuous groove part is communicated with the unallocated part of continuous groove in continual mode, each continuous intercolpium comprises that first leg and that is positioned at outer shroud is positioned at second leg of ring, and first and second legs intersect on center radius and the formation angle.

Further feature of the present invention is clearly disclosed in the part that is entitled as " implementing optimal mode of the present invention ".

Brief description of the drawings

In order to understand the present invention more fully, below to implement in the detailed description that optimal mode of the present invention is a topic with reference to following accompanying drawing:

Fig. 1 is the drawing in side sectional elevation with a mandrel electric machine assembly that combines according to hydrodynamic thrust bearings of the present invention;

The fragmentary perspective view on one of surface of the hydrodynamic thrust bearings of a kind of prior art of Fig. 2;

Fig. 3 is because the rotation on the hydrodynamic thrust bearings surface among Fig. 2 and the perspective view of the pressure distribution that produces in bearing fluid;

Fig. 4 is a plotted curve, is illustrated in the quantity of the groove that forms on the hydrodynamic shaft bearing surface, the degree easy to manufacture of this bearing surface and the universal relation between the bearing performance;

Fig. 5 (a) and (b) and (c) stress distribution that solid material is produced is shown under the certain load condition are with specification formed stress in the punch member when forming grooved surface;

Fig. 6 is the fragmentary perspective view on one of surface of the second prior art hydrodynamic thrust bearings;

Fig. 7 is because the rotation on the hydrodynamic thrust bearings surface among Fig. 6 and the perspective view of the pressure distribution that produces in bearing fluid;

Fig. 8 is the fragmentary perspective view on one of surface according to hydrodynamic thrust bearings of the present invention;

Fig. 9 is the planimetric map according to one of bearing surface of the hydrodynamic thrust bearings of optimal mode of the present invention;

Figure 10 is because the rotation on the hydrodynamic thrust bearings surface among Fig. 8 and the perspective view of the pressure distribution that produces in bearing fluid;

Figure 11 is a plotted curve, illustrates according to the groove angle of a kind of hydrodynamic bearing of the present invention and the relation between the bearing performance;

Figure 12 is a plotted curve, illustrates according to the groove ratio of a kind of hydrodynamic bearing of the present invention and the relation between the bearing performance;

Figure 13 is a plotted curve, illustrates according to the groove depth of a kind of hydrodynamic bearing of the present invention and the relation between the bearing performance;

Figure 14 is a plotted curve, illustrates according to the center radius of a kind of hydrodynamic bearing of the present invention and the relation between the bearing performance;

Figure 15 is a plotted curve, is illustrated in according to the relation between the flow on pressure reduction on the cross section of a kind of hydrodynamic bearing of the present invention and the bearing cross section;

Figure 16 is a plotted curve, illustrates by the pressure distribution that bearing surface produced shown in Fig. 2,6 and 8.

Implement optimal mode of the present invention

Because it is known that hard disk drive and mandrel motor are in related domain,, a lot of known details have been omitted in this specification for fear of obscuring when those skilled in the art's generation when implementing to propose claim of the present invention.

Fig. 1 shows the cross section with the mandrel electric machine assembly that combines according to a kind of hydrodynamic thrust bearings of the present invention.Comprise a substrate 12 and an assembly 13 of turning with the mandrel electric machine assembly of label 10 expression generally.

Be installed in the substrate 12 by a nut 16 for one 14.

The hole of axle 14 outer surface on an adjacent axle journal 18 forms a filmatic bearing 20.Filmatic bearing 20 comprises that one is located on the axle 14 or the grooved surface on the hole of axle journal 18.Shaft bearing 20 supports axle journal 18, and it is rotated around axis 22 with respect to axle 14.

One push pedal 24 is force-fitted in an end of axle 14, and extends perpendicular to axle 14.Push pedal 24 limits one first and pushes away face, and the adjacent face that pushes away on itself and the axle journal 18 limits a first fluid power thrust bearing 26.

One ends plate 28 and push pedal 24 adjacent being force-fitted on the axle journal 18.End plate 28 and limit one and end plate and push away face, it one second is pushed away face and limits one second hydrodynamic thrust bearings 30 with what limit by push pedal 24.End plate 28 and be sealed in axle journal 18 by means of an O type circle 32.

First and second

hydrodynamic thrust bearings

26,30 respectively comprise the bearing surface of a fluting, and this will describe with reference to figure 9 below.In the embodiment of this fluid bearing unit, the surface of these flutings is provided in the push pedal 26.Yet, also can be provided on the adjacently situated surfaces that ends plate 30 and/or axle journal 18.

One turns 34 around axle journal 26 assemblings.The disk (not shown) is arranged in 34 supports one of turning.

During use, an electromagnetic machine drives the assembly 13 of turning with respect to substrate 12 rotations.Electromagnetic machine comprises that one is installed in stator module 36 and in the substrate 12 and is installed in magnet 38 on the axle journal 18.

Hydrodynamic thrust bearings

26 and 30 prevents that axle journal 18 is with respect to any tangible linear motion of axle 14 along axis 22.

Can understand the running of hydrodynamic bearing best with reference to figure 2, Fig. 2 illustrates the fragmentary perspective view on one of surface of the hydrodynamic thrust bearings of prior art.

Hydrodynamic bearing surface with label 60 expressions comprises a series of staggered grooves 62 and intercolpium 64 generally.For the purpose of illustrating, the degree of depth of the diameter of hydrodynamic shaft bearing surface 60 and groove 62 has been exaggerated many.

Each groove 62 and intercolpium 64 comprise a leg that extends internally from the external diameter 68 of hydrodynamic shaft bearing surface 60 from the internal diameter 66 outward extending legs of hydrodynamic shaft bearing surface 60 and.Two legs intersect at a middle radius 70 places, and this middle radius is referred to as center radius in the art.These a plurality of grooves 62 and intercolpium 64 form the herringbone pattern of a curve together, as shown in the figure.

When the adjacent setting of bearing surface 60 bearing surface relative, and make and just form a hydrodynamic thrust bearings when one deck lubricant film is arranged between the two sides with one.When bearing surface 60 along direction 72, when promptly rotating against herringbone pattern, groove 62 and intercolpium 64 will be with oiling agent from interior

external diameter

66 and 68 to the some place suction of herringbone pattern on center radius 70.So just be formed on a kind of pressure distribution in the oiling agent that crosses bearing surface 60, this pressure distribution is used to keep the diaxon bearing surface to load down outside to separate.

Fig. 3 shows the pressure distribution of crossing the hydrodynamic bearing that has eight grooves that comprises hydrodynamic shaft bearing surface 60.In the figure, bearing means has been added with the load of 14.2N, and the cod rigidity of 4260kN/m and the bearing roll stiffness of 14.27Nm/rad. are provided.

When the quantity of groove on the bearing surface and intercolpium increased, bearing performance was increased to a peak.In Fig. 4, with the quantity of line 80 expression grooves and the relation between the bearing performance.Bearing performance no longer included tangible growth when as can be seen from Figure 4, the quantity of groove surpassed a certain value.

In Fig. 4, the relation between the degree easy to manufacture of the bearing surface of line 82 expression flutings and the quantity of groove.As can be seen from the figure, originally, when the quantity of groove was lower than a certain numerical value, the easy degree of manufacturing was constant, but along with the increase of the quantity of groove, the easy degree of manufacturing sharply reduces.

Can understand this relation between the quantity of the degree easy to manufacture of bearing surface and groove best with reference to figure 5.

Fig. 5 (a) illustrates the stress distribution of crossing on the plane 90 when applying a power F by 92 pairs of planes 90 of a ball.This stress distribution has a kind of shape of clock, and summit is just in time under the center of ball 92.

Fig. 5 (b) illustrates the stress distribution situation when the angle by 96 pairs one material pieces 98 of a ball applies a power F.Stress distribution in the material piece is along with the bell shape of falling of front, and with label 100 expressions, but near edge 102, stress distribution sharply descends, with label 104 expressions.

Be used to form on the drift of groove, stress distribution is roughly the stress distribution 104 among Fig. 5 (b) and the summation of 100 two mirror images.The stress distribution that is caused is represented with label 106 in Fig. 5 (c).Along with the width of drift 108 reduces, when forming narrower groove, need like this, the average stress of crossing drift increases sharply, and at this moment edge stress distributes and has played leading role.

Therefore, see Fig. 3 again, in general, need more groove in order to increase bearing performance, thereby reduced the width of each groove.Narrow groove need form with narrower drift (or mould) parts.Narrower punch member is subjected to much bigger stress, can reduce the drift life-span like this, thereby causes making the decline of the easy degree of grooved shaft bearing surface.

The hydrodynamic shaft bearing surface of another kind of prior art shown in Fig. 6, it has 12 grooves.The pressure distribution that this bearing surface produced is shown in Fig. 7.In the figure, also this bearing means is imposed the load of 14.2N, and the cod rigidity of 4560kN/m and the bearing roll stiffness of 14.95Nm/rad are provided, back two data are higher than the corresponding data that the sort of structure provided among Fig. 2.

Fig. 2 and Fig. 6, Fig. 3 and Fig. 7 are compared as can be seen, and the quantity of groove 62 is increased to 12 total increases that cause crossing the pressure distribution of bearing surface from eight, but the width of each groove 62 descends significantly.

In Fig. 8,, and in Fig. 9, show according to hydrodynamic thrust bearings of the present invention with plane view with simple and clear perspective view.For convenience's sake, represent with identical label with the common feature of the bearing surface among Fig. 9 for Fig. 8.

With label 120 expressions, it defines the intercolpium 122 of plurality of continuous to bearing surface shown in Figure 8 generally.Intercolpium 122 extends to an external diameter 126 from the internal diameter 124 of bearing surface 120.Adjacent continuous intercolpium 122 limits the continuous groove 128 between them, and groove 128 extends in continual mode between internal diameter 124 and external diameter 126, and the degree of depth of groove is roughly constant.

As can see from Figure 8, each continuous groove 128 comprise one bearing surface 120 one in the ring in the outer shroud of unallocated part 130 and at bearing surface 120 in division part 132.Continuous groove is marked off by a middle intercolpium 134 between two adjacent continuous intercolpiums 122 and divides part 132.

The division part 132 that should be noted that continuous groove 128 is communicated with the unallocated part 130 of continuous groove 128 in continual mode.So just guaranteed that bearing lubricant can flow between interior

external diameter

124 and 126 along continuous groove basically without restriction.Believe that this level and smooth flowing can improve bearing performance, and guarantee can not form a kind of undesirable high pressure on any position of bearing surface or cavity occur crossing, the appearance of this high pressure or cavity can increase the suffered stress of continuous intercolpium 122 or median surface 134.

Each continuous intercolpium 122 comprises that second leg, 138, the first and second legs 136,138 of ring that first leg 136 and that is positioned at the outer shroud of bearing surface 120 is positioned at bearing surface 120 intersect at center radius 140 places.First and second legs 136,138 each other at angle, continuous intercolpium 122 limits the herringbone pattern of a curve with adjacent continuous intercolpium 122, as shown in the figure.

The pressure distribution that produces on the bearing surface shown in Figure 8 has been shown among Figure 10.In the figure, bearing means is applied the load of 13.91N, and the cod rigidity of 4810kN/m and the bearing roll stiffness of 15.37Nm/rad are provided, all higher than the structure among Fig. 2 and Fig. 6.

Now with particular reference to Fig. 9, and consider the sense of rotation 142 of bearing surface 120 to be appreciated that first and second legs 136,138 of continuous intercolpium 122 respectively have guide margin 144,146 and trailing edge 148,150.In near first and second leg 136,138 intersections center radius 140, trailing edge 148,150 forms a smoothed curve.In illustrated embodiments of the invention, this smoothed curve is the circular arc 152 that a radius is roughly 50 μ m.

It can also be seen that, also form a smoothed curve in trailing edge 150 intersection on internal diameter 124 of the guide margin 146 of second leg 138 and adjacent second leg.In the illustrated embodiment, this smoothed curve is the circular arc 154 that a radius is roughly 25 μ m.

The drift of considering to be used to form bearing surface 120 can be understood the improvement on the degree easy to manufacture of bearing surface 120 best.This drift or mould are opposite with diagram bearing surface 120.In other words, drift have with continuous groove 128 corresponding convex surfaces and with intercolpium 122,134 corresponding grooves.

From this respect Fig. 9, the convex surfaces of drift is continual between internal diameter 124 and external diameter 126.

It can also be seen that the convex surfaces of drift is more even broad between external diameter 126 and internal diameter 124.Narrow zone on the crowning of drift, as mentioned above, this zone can be subjected to undesirable big stress, basically by providing smoothed curve 152,154 to be improved.

The performance of hydrodynamic bearing also depends on groove angle (α).That angle between the tangent line of the tangent line of groove and circle is defined as groove angle.Usually the groove angle of inside groove 130 and water jacket 132 remains unchanged.Hydrodynamic bearing depends on groove angle to a great extent for the pump action of bearing fluid, and this pump action affects the performance of bearing.For hydrodynamic shaft bearing surface shown in Figure 9, groove angle can change between about 19 ° and about 29 ° according to required specific bearing characteristics, but preferably is roughly 23.5 °.Relation between groove angle and the bearing performance has been shown among Figure 11.

Similarly, thus the groove ratio is another to be influenced hydrodynamic shaft and honours the pump action of bearing fluid and influence the parameter of bearing performance.The groove ratio is defined as the ratio between the width of the width of groove and intercolpium, in according to the hydrodynamic bearing of a kind of fluting of the present invention this ratio also can be roughly 0.32 and be roughly 0.6 between change, preferably be roughly 0.5.Relation between ratio of groove shown in Figure 12 and the bearing performance.

The degree of depth of the groove 128 in bearing surface shown in Figure 9 also can change between about 9 μ m and about 13 μ m, is preferably 11 μ m.Relation between groove depth and the bearing performance is shown in Figure 13.

Another parameter that influences bearing performance is the position of center radius 140.Because the arrangement mode of interior water jacket 130,132, they relative to one another, promptly to center radius pumping bearing fluid.The relative length of interior water jacket 103 and 132 has been determined in the position of center radius, thereby and has determined their relative pumping force.As shown in figure 14, bearing performance depends on the position of center radius.

By changing the position of above-mentioned parameter, particularly center radius, can produce the pressure reduction (Δ p) between the bearing fluid at the bearing fluid at internal diameter 124 places and external diameter 126 places.This pressure reduction can produce a kind of net flow of the bearing fluid that crosses bearing surface.By reducing or increasing the Δ p that crosses bearing surface, can control this net flow and pass the direction of bearing with it.Pressure reduction and the relation of passing between the flow of bearing are shown in Figure 15.

At last, Figure 16 shows respectively the comparison of the bearing fluid pressure that the hydrodynamic shaft bearing surface that illustrated by Fig. 2 (eight unallocated grooves), Fig. 6 (12 unallocated grooves) and Fig. 8 (dividing groove for eight) produced.As can be seen from the figure, hydrodynamic thrust bearings of the present invention has the highest surge pressure in pressure minimum that the embodiment than Fig. 2 improved and the three kinds of bearing surfaces, and total pressure distribution improves.

Therefore as can be seen, hydrodynamic shaft bearing surface of the present invention not only provides a kind of improvement of performance of the bearing means to illustrated prior art, and easier making.

Should be appreciated that, the invention is not restricted to the foregoing description, under the prerequisite that does not deviate from the spirit and scope of the present invention, can make many improvement.For example, can between adjacent continuous intercolpium 122, provide additional middle intercolpium 134 further to divide continuous groove 128.

Claims

1. the hydrodynamic thrust bearings of a fluting, it comprises first and second bearing surfaces that can rotate relative to one another, and has bearing fluid between the diaxon bearing surface,

The clutch shaft bearing face limit a plurality of from the clutch shaft bearing face one in the intercolpium of an external diameter of the clutch shaft bearing face connection of extending radially,

Adjacent continuous intercolpium limits a continuous groove between them, this groove has the degree of depth of a constant, and extends between internal diameter and external diameter in continuous mode,

This continuous groove comprises that an interior end division part and of interior ring that is limited to the clutch shaft bearing face is limited to the interior division part of an outer shroud of clutch shaft bearing face, continuous groove in dividing part by one between adjacent continuous intercolpium one in the middle of the intercolpium division

The division of continuous groove part is communicated with the unallocated part of continuous groove in continual mode,

Each continuous intercolpium comprises that first leg and that is positioned at outer shroud is positioned at second leg of ring, and first and second leg intersects at a center radius place and also constitutes angle each other.

2. the hydrodynamic thrust bearings of fluting as claimed in claim 1 is characterized in that: each continuous intercolpium limits an operation guide margin and an operation trailing edge, and the operation guide margin limits a smoothed curve in the first and second leg intersections.

3. the hydrodynamic thrust bearings of fluting as claimed in claim 2 is characterized in that: the operation guide margin of adjacent continuous intercolpium and operation trailing edge intersect with a smoothed curve on internal diameter.

4. the hydrodynamic thrust bearings of fluting as claimed in claim 2 is characterized in that: the operation smoothed curve that guide margin limited is one section circular arc.

5. the hydrodynamic thrust bearings of fluting as claimed in claim 4 is characterized in that: it is the circular arc that one section radius is roughly 25 μ m that the operation guide margin intersects the smoothed curve that the place limits at first and second legs.

6. the bearing means of the hydrodynamic thrust bearings of a fluting that comprises claim 1, it comprises:

One axle journal, it limits a journal hole, also limits an axle journal that extends perpendicular to journal hole and pushes away face;

One is installed in the axle in the journal hole, and this axle and journal hole limit filmatic bearing together, and this bearing allows axle and axle journal to rotate relative to one another;

One laterally leaves axle extends and limits first and second push pedals that push away face, and first pushes away face pushes away face with axle journal and limit a first fluid power thrust bearing; And

One is installed on the axle journal and limits one and ends the plate that ends that plate pushes away face, and end plate and push away face and push away face with second and limit one second hydrodynamic thrust bearings,

In first and second hydrodynamic thrust bearings at least one pushes away the push away face of face for fluting, its limit a plurality of from fluting push away face one in radially fluting push away the continuous intercolpium that an external diameter of face extends,

Limit a continuous groove between adjacent continuous groove between them, this groove extends between internal diameter and external diameter in continual mode, and has the degree of depth of a constant,

Continuous groove is included in an interior unallocated part and the stroke portions in an external diameter of the face that pushes away of slotting of an internal diameter of the face that pushes away of fluting,

Continuous groove is divided by the middle intercolpium between adjacent continuous intercolpium in dividing part,

Each continuous intercolpium comprises that first leg and that is positioned at outer shroud is positioned at second leg of ring, and first and second legs intersect on center radius and the formation angle.

7. the hydrodynamic thrust bearings of fluting as claimed in claim 6 is characterized in that: each continuous intercolpium limits an operation guide margin and an operation trailing edge, and the operation guide margin limits a smoothed curve in the first and second leg intersections.

8. the hydrodynamic thrust bearings of fluting as claimed in claim 7 is characterized in that: the operation guide margin of adjacent continuous intercolpium intersects with smoothed curve on internal diameter with the operation trailing edge.

9. the hydrodynamic thrust bearings of fluting as claimed in claim 7 is characterized in that: by the operation smoothed curve that guide margin limited is one section circular arc.

10. the hydrodynamic thrust bearings of fluting as claimed in claim 9 is characterized in that: intersecting the smoothed curve that the place limits by the operation guide margin at first and second legs is the circular arc that one section radius is roughly 25 μ m.