CN101128679B - Fluid bearing device and method of manufacturing the same - Google Patents

Abstract

The invention relates to a housing of a fluid bearing device and a housing for a dynamic pressure bearing device capable of stably developing high bearing performance and manufacturable at low cost, and a method of manufacturing the housings for the fluid bearing device and the dynamic pressure bearing device capable of increasing the accuracy of the shape of these housings at low cost. When the housing (7) having, on its outer periphery, a fixed surface (7c) formed in a cylindrical shape and fixing the outer peripheral surface (8b) of a bearing sleeve (8) and an axial communication groove (7d) allowing both end faces (8c) and (8d) of the bearing sleeve (8) to communicate with each other is formed by forging, a groove forming part (18a2) is formed on the outer peripheral part of a rod (18) which is used as a mold for the inner periphery of the housing (7), and the communication groove (7d) is forged by the groove forming part (18a2). Also, after a seal surface (107d) and a cylindrical outer peripheral surface (107e) formed on the outer periphery of the housing (107) are forged, the inner peripheral surface (107c) thereof is forged. Thus, the squareness of a thrust bearing surface (107a) relative to the inner peripheral surface (107c) or the outer peripheral surface (107e) can be finished to 20 m or below. Also, the concentricity of the seal surface (107d) relative to the inner peripheral surface (107c) or the outer peripheral surface (107e) can be finished to 20 m or below. In addition, the concentricity of the outer peripheral surface (107e) relative to the inner peripheral surface (107c) can be finished to 20 m or below.

Description

Hydrodynamic bearing device and production method thereof

Technical field

The present invention relates to a kind of hydrodynamic bearing device and production method thereof.Hydrodynamic bearing device and production method thereof comprise the housing of the spindle motor that is applicable to information equipment; For example; Disk units such as HDD, compact disk equipments such as CD-ROM, CD-R/RW, DVD-ROM/RAM, MD, MO equimagnetic-compact disk equipment are used spindle motor; The multifaceted prism scan module of laser printer (LBP), and other micro-machine.

Background technique

For above-mentioned various motors, need high running accuracy, at a high speed, low cost, low noise etc.Determine one in the element of these desired properties to be the bearing that supports this electric machine main shaft.In recent years, at the fluid bearing that has excellent specific property aspect the above-mentioned desired properties just by on probation or used by reality.

Such fluid bearing can roughly be divided into: hydraulic bearing, this hydraulic bearing comprise the dynamic pressure generation device that produces dynamic pressure fluid (for example lubricated wet goods); And cylindrical bearing (bearing with complete circular shaft bearing surface), this cylindrical bearing does not have the dynamic pressure generation device.

For example, in the fluid bearing device in the spindle motor that is integrated into disc drive unit such as HDD, hydraulic bearing constitutes the radial bearing part that supports rotating member diametrically simultaneously and supports the thrust-bearing part of rotating member in thrust direction.For example; The known thrust bearing division branch that is used in such fluid bearing device (dynamic pressure bearing device) comprises dynamic pressure groove or thrust-bearing gap as dynamic pressure generating section; Aforementioned dynamic pressure groove is formed on two end faces of the flange portion of the axial region that is provided with on the rotating member, those faces relative with these two end faces (end face of bearing housing, housing or be fixed on the upper-end surface of the thrust component bottom on the housing; The end face of cover component etc.) on one in; Aforementioned thrust-bearing gap is formed on (for example, referring to the open communique No.2003-239951 of japanese unexamined patent) between two faces.

In addition; A kind of known bearing is arranged; Wherein the external peripheral surface of bearing housing is provided with the groove (circulating tanks) that fluid circulates vertically; This groove is used for suitably keeping away from the hydrodynamic pressure (keeping the pressure balance with other part) (for example, referring to the open communique No.2003-307212 of japanese unexamined patent) in the zone of air openings side (for example, be positioned on the inboard with the relative side of seal space of housing thrust-bearing part) (like seal space etc.).

Such bearing apparatus is made up of housing, bearing housing, shaft component and other parts.In order to ensure improving the required high support performance of information equipment performance, people are at processing accuracy and the assembly precision of making great efforts to improve each parts.Yet along with price descends and the information equipment miniaturization, this bearing apparatus also is asked to reduce cost and miniaturization just gradually.

Particularly, miniaturization and portable needs in order to satisfy recent information equipment begin to note that each size of component of studying bearing apparatus reduces.For example, reduce for the size of cylindrical shaft bearing sleeve, attenuation is necessary.Yet, circulating tanks is set on the outer circumferential face of bearing housing can produces the unfavorable effect that is described below accordingly.

Bearing housing is formed by sintering metal usually, and behind sintering, through according to size manufacturing (sizing), dynamic pressure generating sections such as dynamic pressure groove are formed on the inner peripheral surface of bearing housing.After making according to size, from the bearing housing elastic recovery that mould etc. shifts out, its outer circumferential face moves (expansions) and arrives the outer diameter side.During making according to size, the circulating tanks of external peripheral surface and mould etc. do not contact, so can not act on pressure in the inner diameter side, so its elastic recovery amount occupies a narrow space than other.Quantity (for example, three) through the regulating ring chute can be reduced to the imbalance of elastic recovery amount to a certain degree.Yet as stated, it is thin more that wall thickness becomes, and it is more uneven that the elastic recovery amount just becomes.Under this sample loading mode, after making according to size, the inner circumferential surface of bearing housing and external peripheral surface no longer are perfect circles, but ellipse or roughly polygonal cross section, first diameter of aforementioned ellipse be positioned at circulating tanks near.Therefore, it is big that the variation on the circumferencial direction in the radial bearing gap between bearing housing and the axial region just becomes, and this can cause the stable bearing rigidity can not be provided.

Recently, in order to deal with the increase of information recording density and rotational speed in the information equipment,, even need higher running accuracy for the spindle motor of above-mentioned information equipment.For satisfying such demand, the dynamic pressure bearing device that is integrated in the above-mentioned spindle motor is asked to have higher running accuracy equally.

For the running accuracy (support performance) of improving dynamic pressure bearing device, control more accurately produces the radial bearing gap and the thrust-bearing gap of dynamic pressure.Therefore, the element of the dynamic pressure bearing device relevant with the formation of above-mentioned bearing play need have high dimensional accuracy.

On the contrary, recently, for the size and the quantity of parts that reduces bearing apparatus, the above-mentioned thrust-bearing of formation gap between the end face of the end face of housing and rotating member on the other side (for example, dish hub).

Like this,, not only require shaft component and bearing housing to have high dimensional accuracy, and require also to have high dimensional accuracy as the end region of the thrust bearing surface of housing in order to realize the higher running accuracy of bearing apparatus.Replacedly, other face of formation housing also requires to have excellent high accuracy to shape.Yet existing processing method can not improve this precision, because processing cost significantly increases.

Summary of the invention

First purpose of the present invention provides a kind of hydrodynamic bearing device, and it can produce high support performance reliably with low cost.

Second purpose of the present invention provides a kind of dynamic pressure bearing device with improved form accuracy and uses housing.

The 3rd purpose of the present invention provides the production method of a kind of dynamic pressure bearing device with housing, and it can improve the form accuracy (accuracy of form) of this shells with low cost.

In order to realize above-mentioned first purpose; The present invention provides a kind of hydrodynamic bearing device; This housing forms cylindrical and has and is fixed to the stationary plane on the inner peripheral surface on the inner peripheral surface of housing, that be formed on housing to the external peripheral surface of bearing housing; This inner peripheral surface comprises the axial rings chute that is formed on the inner peripheral surface, and this axial rings chute is used to make two end faces of bearing housing to form circulate (circulation), and this stationary plane and circulating tanks all pass through to forge and form.

Therefore, form the axial rings chute of circulate, on whole circumference, be made uniformity in the elastic recovery amount of making the rear axle bearing sleeve according to size through two axial ends that on the housing inner peripheral surface, are provided for making bearing housing.Therefore, the circularity of the inner circumferential surface of bearing housing or external peripheral surface can be held very accurate.For example, the radial bearing gap between inner circumferential surface and the rotating member can be by suitably control.In addition, when the axial rings chute is arranged on the external peripheral surface of bearing housing, utilize green compact (green compact) moulding to carry out the moulding of circulating tanks simultaneously.The mould and the drift of green compact forming die that therefore, need be corresponding with circulating tanks.Yet, in the present invention,, can simplify such mould and reduce required cost through circulating tanks is arranged on the case side.

The example that is used for a kind of possibility method of formation axial rings chute on the housing inner peripheral surface is cutting.Yet, by this way,, also need other treatment step except on the housing inner peripheral surface, forming the process of stationary plane, cause expensive.In addition, in cutting, can produce the cutting powder inevitably, the cutting powder can get in the fluid as pollutant.In order to prevent this situation, need complicated cleaning, for example, and the extra housing cleaning course after cutting several times independently, this causes more expensive.

In contrast, in the present invention, the forging that circulating tanks and stationary plane all pass through identical process forms, and therefore, compares with the situation that independent step forms with them, and cost is lowered.In addition, forging process generally has the shorter cycle than working angles, therefore, has improved (the extensive manufacturing) manufacturing efficiency.In addition, different with cutting, in forging process, can not produce the cutting powder, therefore, compare by the situation that resin forms with housing, suppressed the formation of burr (burrs).Therefore, simplified clean operation, eliminated the worries of removing flash removal again, realized that further cost reduces.

In addition; In order to realize above-mentioned first purpose; The present invention provides the production method of a kind of fluid bearing device with housing, and this method is included in the moulding of fluid bearing device with housing, and the Slot shaping part of the stroke direction extension that is parallel to mould is set on forge mould; And utilizing this Slot shaping partly to form circulating tanks through forging, aforementioned housing has cylindrical and comprises the stationary plane on the inner peripheral surface external peripheral surface that is used for fixing bearing housing, be formed on housing through forging.

As stated, use the forge mould of the Slot shaping part that is provided with the stroke direction extension that is parallel to mould, form circulating tanks through forging, therefore, the axial rings chute accurately and easily is formed on the housing inner peripheral surface.

In addition; Through being provided on forge mould, forming the face moulding section of stationary plane with Slot shaping part; Utilize Slot shaping part and face moulding section to form circulating tanks and stationary plane through forging; Therefore, in single forging and pressing process (stroke), form the stationary plane and the circulating tanks of housing simultaneously.This can further shorten the cycle, guarantees further to improve mass production efficient.

Housing with above-mentioned structure can be used to fluid bearing device, and this fluid bearing device for example comprises: this housing; Be fixed on the bearing housing on the stationary plane of housing; Rotating member with respect to bearing housing and housing rotation; Radial bearing part, this radial bearing partly support rotating member through the mode that the fluid lubrication oil film that occurs in the radial bearing gap between rotating member and the bearing housing supports with non-contact diametrically; With on the open end side that is arranged on housing and towards the open seal space of air.

Fluid bearing device with above-mentioned structure can be by structure like this, and for example, fluid circulates between the inside of the other end of housing and seal space structure.This structure can suitably keep the pressure balance of bearing internal flow, therefore can produce long stable support performance (bearingperformance).

Fluid bearing device with above-mentioned structure also is used to disk unit and uses spindle motor, and this disk unit has this fluid bearing device.

In order to realize above-mentioned second purpose; The present invention provides a kind of dynamic pressure bearing device to use housing; This housing is cylindrical forging product and comprises thrust bearing surface; This thrust bearing surface forms the thrust-bearing gap between the housing and the rotating member that will support, and this thrust bearing surface is 20 μ m or littler with respect to the perpendicularity of inner peripheral surface or external peripheral surface.Above-mentioned perpendicularity is meant the margin of error (the amount of the disorder) of planar configuration (being meant thrust bearing surface here); Aforementioned planar configuration is parallel to respect to the axis of reference vertical geometry plane of (refer to connect the line at center of section profile of each section of inner circumferential surface or external peripheral surface here, be designated hereinafter simply as the axis of inner circumferential surface or external peripheral surface).When through between being placed on perpendicular to two of axis of reference (axis of inner circumferential surface or external peripheral surface) how much parallel surfaces, planar configuration (thrust bearing surface) time, the margin of error of thrust bearing surface is represented the interval between two planes at the some place that the interval of two parallel surfaces is minimum.Note that the thrust bearing surface of mentioning can be any bearing surface towards the thrust-bearing gap that produces dynamic pressure effect here, it is unimportant whether it has the dynamic pressure groove that produces dynamic pressure effect.

In addition; In order to realize above-mentioned second purpose; The present invention provides a kind of dynamic pressure bearing device to use housing, and this housing is cylindrical forging product and comprises thrust bearing surface and sealing surface, and aforementioned thrust bearing surface forms the thrust-bearing gap between the housing and the rotating member that will support; Aforementioned sealing surface forms the seal space between housing and rotating member, and sealing surface is 20 μ m or littler with respect to the coaxality of inner circumferential surface or external peripheral surface.Above-mentioned coaxality be meant will with axis and the error size (dimension of disorder) of axis of reference (here be meant the axis of inner circumferential surface or external peripheral surface) of axis of reference on same straight line (be meant the line at center of the section profile of each section that is connected sealing surface here, be designated hereinafter simply as the sealing surface axis).This error size quantity representes that by the minimum cylinder of the diameter in the geometric correction cylinder aforementioned geometric correction cylinder comprises above-mentioned whole axis (axis of sealing surface) and coaxial with axis of reference (axis of inner circumferential surface or external peripheral surface).

In addition; In order to realize above-mentioned second purpose; The present invention provides a kind of dynamic pressure bearing device to use housing; This housing is cylindrical forging product and comprises thrust bearing surface, and this thrust bearing surface forms the thrust-bearing gap between the housing and the rotating member that will support, and external peripheral surface is 20 μ m or littler with respect to the coaxality of inner circumferential surface.Here the coaxality of mentioning be meant will and the error of axis of reference (axis that refers to inner circumferential surface here) between axis on the same straight line (axis that refers to external peripheral surface here) and axis of reference.This margin of error representes that by the minimum cylinder of the diameter in the geometric correction cylinder aforementioned geometric correction cylinder comprises above-mentioned whole axis (axis of external peripheral surface) and coaxial with axis of reference (axis of inner circumferential surface).

Geometrical deviation (form accuracy) between the above-mentioned surface of formation housing is based on following invention discovery realization.

Thrust bearing surface has very big influence with respect to the perpendicularity of inner peripheral surface or external peripheral surface to the precision in the thrust-bearing gap between the end face of thrust bearing surface and rotating member on the other side.That is, the perpendicularity of above-mentioned thrust bearing surface is greater than 20 μ m, and the difference between the wide part in above-mentioned thrust-bearing gap and the narrow part just becomes remarkable.Therefore; The torque of the shaft component at the narrow part place of above-mentioned bearing play just becomes and is higher than other part; Increase bearing loss; Simultaneously the rigidity of support of the wide part of above-mentioned bearing play is lower than other part, this possibly reduce unfriendly unrepeatable departing from (non-repeatable runout, NRRO).In addition, the rotating member needed time that floats increases behind electric motor starting, and sliding friction during this period increases, and this can influence bearing life nocuously.Based on such viewpoint, in the present invention, thrust bearing surface is 20 μ m with respect to the perpendicularity of inner circumferential surface or external peripheral surface.

In addition, in the seal space that forms between sealing surface and the rotating member on the other side, sealing surface is important with respect to the inner circumferential surface of housing or the coaxality of external peripheral surface.When coaxality does not satisfy (greater than 20 μ m), even bearing housing very accurately is installed on the housing, the sealing surface of housing that will be relative with this surface is arranged on the difficulty that just becomes on the rotating member side, and aforementioned rotating member side is relative with fixed intervals with this surface.This can cause the variation and the reduction sealability of the seal clearance of the seal space that forms between two surfaces in a circumferential direction.Based on such reason, in the present invention, sealing surface is set to 20 μ m or littler with respect to the coaxality of inner circumferential surface or external peripheral surface.

In addition; As stated; The inner circumferential surface of housing is as the installation reference of the bearing housing of rotating member (axial region), and the external peripheral surface of housing is as the dynamic pressure bearing device that bearing housing and rotating member are installed on its housing is integrated into the reference by location in the motor simultaneously.Therefore; If the coaxality bad (greater than 20 μ m) between two surfaces; For example; The installation precision of the fixed side member (support etc.) of motor is lowered, and the precision of the coil of generation motor driving power and the relative spacing of magnet just is difficult to suitably control, and this can influence the running accuracy of motor unfriendly.Based on such reason, in the present invention, external peripheral surface is set to 20 μ m or littler with respect to the coaxality of the inner circumferential surface of housing.

The example of other form accuracy of the housing that satisfies comprises the perpendicularity of thrust bearing surface with respect to the axis of sealing surface.This perpendicularity is desirably 20 μ m or littler.The example of other form accuracy that satisfy in addition, comprises depart from (runout) of sealing surface with respect to the axis of inner circumferential surface.This departs from (runout) and is desirably 20 μ m or littler.The example of other form accuracy that satisfy further, comprises the profile of sealing surface.This profile is desirably 20 μ m or littler.When in these geometrical deviations about sealing surface (perpendicularity, depart from the surface, profile) at least one satisfied, these geometrical deviations about sealing surface were acceptable, but it is then better to satisfy in the above-mentioned geometrical deviation two or more.

In addition; In order to realize above-mentioned the 3rd purpose; The present invention provides the production method of a kind of dynamic pressure bearing device with housing, and this housing has cylindrical and comprises thrust bearing surface and sealing surface, and aforementioned thrust bearing surface forms the thrust-bearing gap between the housing and the rotating member that will support; Aforementioned sealing surface forms the seal space between housing and rotating member, and this method comprises through the external peripheral surface that forges the formation housing, then through forging the step that forms inner circumferential surface.

In cylindrical housings, for example, its thrust bearing surface side often is formed to such an extent that be thicker than a side relative with thrust bearing surface (side opposite with thrust bearing surface) so that guarantee the reasoning bearing region or for other purpose.In this case, for example, if after through the inner circumferential surface that forges the formation housing, pass through to forge when forming external peripheral surface, the hole that previously on inner peripheral surface, forms will be out of shape, and the precision in this hole just can not be in maintenance.In addition, possibly be difficult to the moulding thick wall part.In contrast, in the present invention,, just can overcome such problem and make it possible to accurately form thrust bearing surface if after through the external peripheral surface that forges the formation housing, pass through to forge when forming inner circumferential surface.In addition, because these are through forging molding, different with the machining of lathe cutting, it can reduce performance period, after the forming processes with forming processes before the ratio of quantity of material increase the cost of material reduction that caused etc.In addition, different with the machining of lathe cutting, can not produce the cutting powder, can suppress the generation of burr.Therefore, through simplifying the operation and eliminating the worries of removing flash removal again, realized the further reduction of cost.

Usually carry out the forging of the inner circumferential surface of housing through passing case material in the axial direction.At this moment, preferably pass case material in the axial direction from a lateral thrust bearing surface side relative with thrust bearing surface.According to this method, because the distortion of the thrust bearing surface that perforation causes is lowered.Therefore, can form inner circumferential surface, the shape of the previous external peripheral surface that forms can accurately be kept simultaneously.

Dynamic pressure bearing device through the said process manufacturing can for example have excellent form accuracy (perpendicularity, coaxality, inclination) with housing between the above-mentioned surface that constitutes housing.

Above-mentioned housing also can so constitute makes dynamic pressure generating section be formed on the thrust bearing surface.In this case, the hydrodynamic effect that produces in the thrust-bearing gap between the thrust bearing surface through housing and the end face of rotating member on the other side, rotating member is supported on thrust direction by the mode that supports with non-contact.

In addition, above-mentioned housing can so constitute makes its two axial ends opening all, the distolateral thrust bearing surface that is provided with, and another is distolateral to utilize cover component sealing.

Housing with above-mentioned structure can be used in the dynamic pressure bearing device that for example has this housing.In addition, this dynamic pressure bearing device also can be used for comprising the motor of this dynamic pressure bearing device.

As stated, according to the present invention, the fluid bearing device that can stably produce high support performance can be with the low cost manufacturing.

In addition,, not only can process the thrust bearing surface of dynamic pressure bearing device, and can very accurately process each surface that constitutes housing and very accurately control the thrust-bearing gap that forms between housing and the rotating member with housing according to the present invention.In addition, forge as manufacturing process through using at that time, can cut down finished cost.

Description of drawings

Fig. 1 shows that the information equipment of fluid bearing device of the integrated with good grounds first embodiment of the present invention is with the sectional view of spindle motor;

Fig. 2 shows the sectional view of fluid bearing device;

Fig. 3 shows the longitudinal sectional view of bearing housing;

Fig. 4 shows the upper-end surface of housing;

Fig. 5 shows the schematic representation of example of the manufacture process of housing;

Fig. 6 shows the sectional view of the forge mould (forging mold) of A-A along the line;

Fig. 7 is the sectional view of fluid bearing device according to a second embodiment of the present invention;

Fig. 8 is the sectional view of the fluid bearing device of a third embodiment in accordance with the invention;

Fig. 9 is the sectional view of the fluid bearing device of a fourth embodiment in accordance with the invention;

Figure 10 is integrated with the information equipment of dynamic pressure bearing device of fifth embodiment of the invention with the sectional view of spindle motor;

Figure 11 is the sectional view of dynamic pressure bearing device;

Figure 12 is the longitudinal sectional view of bearing housing;

Figure 13 shows the upper-end surface of housing;

Figure 14 is the schematic representation of example that shows the manufacture process of housing;

Figure 15 is integrated with the present invention Liu embodiment's the information equipment of dynamic pressure bearing device with the sectional view of spindle motor;

Figure 16 is the sectional view of dynamic pressure bearing device.

Embodiment

Below with reference to the accompanying drawing 1-6 explanation first embodiment of the present invention.

Fig. 1 summarily shows the topology example of the information equipment of the hydrodynamic bearing device 1 that is integrated with the first embodiment of the present invention with spindle motor.Spindle motor is used for disc drive units such as HDD; And comprise hydrodynamic bearing device 1 and electric machine support 6; Hydrodynamic bearing device 1 supports rotating member 3 rotationally; Rotating member 3 comprises the axial region 2 that non-contact is supported, for example, and diametrically across both sides, gap stator coil 4 respect to one another and rotor magnet 5.Stator coil 4 is attached on the outer circumferential face of electric machine support 6, and rotor magnet 5 is attached on the outer circumferential face of rotating member 3.The housing 7 of hydrodynamic bearing device 1 is fixed on the inner peripheral surface of electric machine support 6.Although do not show among the figure that disc-shaped information recording mediums such as one or more disks (being designated hereinafter simply as disk) are maintained on the rotating member 3.In the spindle motor of structure like this, when exciting stator coil 4, the electromagnetic force rotary rotor magnet 5 that produces between stator coil 4 and the rotor magnet 5, therefore, rotating member 3 rotates with axial region 2 with the disk that is rotated member 3 maintenances.

Fig. 2 shows hydrodynamic bearing device 1.Hydrodynamic bearing device 1 by housing 7, be fixed to the bearing housing 8 of housing 7 and constitute as the rotating member 3 that rotates with respect to housing 7 and bearing housing 8 of primary component.Note that for illustrative purposes in following explanation, in the open part of the housing 7 that two axial ends form, be known as downside by a side of lid member 11 sealings, a side relative with sealed sides is known as upside.

Rotating member 3 is made up of the hub portion 9 of the opening side that for example is arranged on housing 7 and the axial region 2 of the inner peripheral surface that inserts bearing housing 8.

Hub portion 9 comprises the disk segment 9a of the opening side (upside) of covering shell 7, from the outer circumferential face of disk segment 9a axially to the column part 9b that extends below, disk supporting plane 9c be arranged on the edge 9d on the outer circumferential face of column part 9b.The disk that does not show is placed on the outer circumferential face of disk segment 9a and is installed on the disk supporting plane 9c.Suitable holding device disk through not showing is maintained at (clamp holder etc.) on the hub portion 9.

Axial region 2 is formed by resin or metal integral ground with hub portion 9, comprises the independently flange portion 10 that prevents slippage in the lower end of axial region 2.Flange portion 10 is made of metal, and is fixed on the axial region 2 through being threaded.Please note that axial region 2 also can be independent of hub portion 9 and form separately.At this moment, axial region 2 can be processed by metal and resin respectively with hub portion 9, perhaps other.

For example, bearing housing 8 is formed by porous body cylindrically, and porous body comprises non-porous body of metal or sintering metal.The sintering metal of the porous body that forms in the present embodiment, comprises the copper as main component cylindrically.

Dynamic pressure groove as dynamic pressure generating section is formed on the inner circumferential surface 8a Zone Full or part area of bearing housing 8.In the present embodiment, for example as shown in Figure 3, axially independently be formed with two zones on the position, on these two zones, be furnished with a plurality of dynamic pressure groove 8a1, the 8a2 of herringbone (herringbone).In the zone that forms dynamic pressure groove 8a1, dynamic pressure groove 8a1 axially is formed asymmetrically with respect to axle center m (axle center in the zone between the upper and lower tipper), and the axial dimension X1 of axle center m upper area is greater than the axial dimension X2 of axle center m lower zone.

Although not shown, for example, on the annular region of the lower end surface of bearing housing 8 8c all or part of, be formed with the zone of arranging a plurality of spirality dynamic pressure grooves on it, as thrust dynamic pressure generation portion.This zone that forms the dynamic pressure groove is relative with upper-end surface 10a as the flange portion 10 of thrust bearing surface.When axial region 2 (rotating member 3) rotated, the thrust-bearing gap of the second thrust-bearing part T2 that will describe below formed and is formed with above that between the zone and upper-end surface 10a (see figure 2) of dynamic pressure groove.

Housing 7 by stainless steel and other metal materials for example to form cylindrically.Housing 7 be shaped as all openings of two axle heads, and one distolateral (lower end side) is by cover component 11 sealings.The all or part of thrust bearing surface 7a that is provided with of the annular region of the end face of opening side (upper-end surface).In the present embodiment, for example as shown in Figure 4, the zone that is furnished with a plurality of spirality dynamic pressure groove 7a1 on it is formed on the thrust bearing surface 7a, as thrust dynamic pressure generation portion.Thrust bearing surface 7a (forming the zone of dynamic pressure groove 7a1 on it) is relative with the lower end surface 9a1 of the disk segment 9a of hub portion 9.When rotating member 3 rotations, the thrust-bearing gap of the first thrust-bearing part T1 that will describe after a while is formed between thrust bearing surface 7a and the lower end surface 9a1 (referring to Fig. 2).

The cover component 11 of the lower end side of seal casinghousing 7 is formed by metallic material or resin material, and it is last to be fixed to shoulder (shoulder) 7b of inner peripheral surface side of the lower end that is arranged on housing 7.Here; Be not limited to concrete fixing means; For example, can select bonding (comprise and freely boning and the pressure fitted bonding), pressure fitted, welding bonding (for example ultrasonic welding), welding means such as (for example, laser beam welding) suitably according to combination and required installation strength, the sealability etc. of material.

On the inner peripheral surface of housing 7, be formed with the stationary plane 7c of the external peripheral surface 8b that is used for fixing bearing housing 8.On this stationary plane 7c, the external peripheral surface 8b of bearing housing 8 is fixed, and for example, fixes through bonding (comprise and freely boning and the pressure fitted bonding), pressure fitted, welding bonding or other suitable means.

In addition, axially extended circulating tanks 7d also is formed on the inner peripheral surface of housing 7 except being formed on the stationary plane 7c.In the present embodiment, as shown in Figure 4, circulating tanks 7d is formed on three positions at interval in a circumferential direction with rule.Be fixed under the state of stationary plane 7c the lower end surface 8c circulate (circulation with) of the lower end of circulating tanks 7d and bearing housing 8, the upper-end surface 8d circulate of upper end and bearing housing 8 at bearing housing 8.In addition, the upper end of circulating tanks 7d also with the thrust-bearing gap circulate (referring to Fig. 2) of the first thrust-bearing part T1.

The conical surface 7e that diameter increases up gradually is formed on the outer circumferential face of housing 7.Conical surface 7e forms ring packing space S 1, and the size of ring packing space S 1 reduces towards the top between the inner circumferential surface 9b1 of conical surface 7e and column part 9b from the sealed sides of housing 7 diametrically gradually.When axial region 2 rotates with hub portion 9, the outer diameter side circulate in the thrust-bearing gap of the seal space S1 and the first thrust-bearing part T1.

In addition, the cylindrical external peripheral surface 7f that has an invariable diameter is formed on the lower end of the outer circumferential face of housing 7.Cylindrical external peripheral surface 7f is fixed on through bonding, pressure fitted or other means on the inner circumferential surface 6a of electric machine support 6, and therefore, hydrodynamic bearing device 1 is integrated in the motor.

The example of the method for making the housing 7 that constitutes hydrodynamic bearing devices 1 is described with reference to figure 5 and 6 below.

In the present embodiment, make housing 7 with three steps: the step of moulding external peripheral surface (A); The step of moulding inner circumferential surface (B); Step (C) with the moulding thrust bearing surface.

(A) step of moulding external peripheral surface

At first; Cold forging is made (compression) and is cut into the cylindricality base material (columnar blank material) that suitable length prepares through stretching wire rod and with it in a pair of mould that does not show, forms the external peripheral surface (conical surface 7e and cylindrical external peripheral surface 7f) of housing 7.The example that note that suitable cold forging making process not only comprises aforesaid upset(ting) method (upsetting), and comprises combination and various other forming method of forward extrusion method (forward extrusion), forward extrusion method and upset(ting) method.

(B) step of moulding inner circumferential surface

Secondly, form the inner circumferential surface (stationary plane 7c and circulating tanks 7d) of housing 7, the inner circumferential surface of this housing 7 will be made case material 7 ' formation through cold forging.As shown in Figure 5; For example; The mould that uses is by mould 16, upper punch (upper punch) 7 ' constitute with low punch (bar) 18, aforementioned mould 16 retrain case materials 7 ' external peripheral surface, aforementioned upper punch 7 ' from the thrust bearing surface 7a side that will form retrain in the axial direction case material 7 '; Aforementioned low punch 18 has the molded surface 18a corresponding to the inner circumferential surface of the housing that will form 7, and molded surface 18a is arranged on the outer circumferential face of low punch 18.Here; As shown in Figure 6; The molded surface 18a that forms the bar 18 of low punch comprises corresponding to the face moulding section 18a1 of stationary plane 7c with corresponding to the Slot shaping part 18a2 of the convexity of circulating tanks 7d; Among the Slot shaping part 18a2 of face moulding section 18a1 and convexity each is arranged in a plurality of positions (in illustrative example, be positioned at three positions, each position at circumferencial direction regularly at interval).Slot shaping part 18a2 is set to make it and extends (Vertical direction among Fig. 5) along the stroke direction that is parallel to bar 18.

As shown in Figure 5, under the restrained situation of case material 7 ' radial and axial, bar 18 raise (in the illustrated direction of arrow) in case pass from lower end side towards upper end side case material 7 ' the inner peripheral surface part.This causes case material 7 ' at axial both ends open, make the shape of face moulding section 18a1 and Slot shaping part 18a2 (the stationary plane 7c of manufactured good and circulating tanks 7d) of copy molded surface 18a form case material 7 ' inner peripheral surface.In the present embodiment, the stationary plane 7c of manufactured good and circulating tanks 7d and shoulder 7b form through bar 18 simultaneously, and bar 18 also has the shoulder moulding section 18b corresponding to shoulder 7b except having the part corresponding to molded surface 18a.Note that in the present embodiment, explained case material 7 ' inner peripheral surface by from downside (side relative) situation to upside (thrust bearing surface 7a side) perforation with thrust bearing surface 7a side.Yet, for example, if there is not the part of special provision perforation directions such as shoulder 7b, also can be from the downward side perforation of upside.

(C) step of moulding thrust bearing surface

At above-mentioned steps (A), (B) afterwards, make the thrust bearing surface 7a of the housing 7 that case material 7 ' formation will form through cold forging.In this forming step, for example, although not shown, the mould of use is made up of the lower end surface of mould shown in Figure 5 16 and bar 18 and upper punch (upper punch) 19, and they constitute the molded surface corresponding with the thrust bearing surface 7a of the housing that will form 7.Retrain diametrically with mould 16 and bar 18 case material 7 firmly ' situation under, upper punch 19 descends, the molded surface (not shown) of upper punch 19 through apply predetermined pressure push case material 7 ' the upper end.Therefore, case material 7 ' the shape of upper-end surface copy molded surface (the thrust bearing surface 7a of manufactured good) form.In addition; In the present embodiment; Although not shown, used dynamic pressure generating section, the groove pattern (groove pattern) corresponding to dynamic pressure groove 7a1 in dynamic pressure generating section is pre-formed on the molded surface of upper punch 19; Therefore, simultaneously case material 7 ' on form the shape of thrust bearing surface 7a and dynamic pressure groove 7a1.

In above-mentioned steps (A)-(C) afterwards, formation is as housing 7 (see figure 2)s of manufactured good.

In the inboard of hydrodynamic bearing device 1, the endoporus (hole of porous body tissue) that comprises bearing housing 8 is full of and lubricant oil arranged (band point zone among Fig. 2).The pasta of lubricant oil always remains in the seal space S1.

When axial region 2 (rotating member 3) rotates, relative with the external peripheral surface 2a of axial region 2 in the both sides in radial bearing gap as the zone (forming dynamic pressure groove 8a1, the zone of 8a2) of the radial bearing surface of the surperficial 8a of the inner peripheral surface of bearing housing 8 in upper and lower two positions.In addition, when axial region 2 rotations, the lubricant oil of top, radial bearing gap is extruded to dynamic pressure groove 8a1, the axle center m side of 8a2, and the pressure of lubricant oil increases.The first radial bearing part R1 and the second radial bearing part R2 are constituted respectively, and the first radial bearing part R1 and the second radial bearing part R2 support axial region 2 through the dynamic pressure effect of dynamic pressure groove with the non-contact mode.

Simultaneously; Pressure effect through moving dynamic pressure groove; Thrust-bearing gap between the lower end surface 9a1 of thrust bearing surface 7a of housing 7 (forming the zone of dynamic pressure groove 7a1) and the hub portion 9 that (disk segment 9a) is relative with it, and the oil film of formation lubricant oil in the thrust-bearing gap between the upper-end surface 10a of lower end surface 8c of bearing housing 8 (forming the zone of dynamic pressure groove) and flange portion on the other side 10 each.In addition, constitute the first thrust-bearing part T1 and the second thrust-bearing part T2 through these oil films, this first thrust-bearing part T1 and the second thrust-bearing part T2 support rotating member 3 with the non-contact mode on thrust direction.

As stated; Axial rings chute 7d is arranged on the inner peripheral surface of housing 7; Therefore, the seal space S1 that is positioned at the thrust-bearing gap of the second inboard thrust-bearing part T2 of the lower end of housing 7 and the opening side that is formed on housing 7 forms circulation through these circulating tanks 7d and is communicated with.Therefore, for example, can avoid fluid (lubricant oil) pressure of the second thrust-bearing part T2 side that any reason causes to rise too high and the too much situation that descends, guarantee on thrust direction, to support rotating member 3 reliably with the non-contact supporting way.

In addition; In the present embodiment; Because the dynamic pressure groove 8a1 of the first radial bearing part R1 is with respect to axle center m (X1＞X2) formation (referring to Fig. 3) in the axial direction asymmetricly; When axial region 2 rotation, the traction (pump suction) of the lubricant oil that causes at upper area place dynamic pressure groove 8a1 is relatively bigger than the traction of lower area.Because the pressure difference of traction; The lubricant oil in the gap between the surperficial 8a of the inner peripheral surface of filled bearing cover 8 and the external peripheral surface 2a of axial region 2 circulates down; And circulation is through the thrust-bearing gap → circulating tanks 7d → upper-end surface 8d of the second thrust-bearing part T2 and the passage in the gap between the 9a1 of lower end surface, so that dragged the into radial bearing gap of the first radial bearing part R1 once more.As stated, through setting such structure, axial rings chute 7d is arranged on the inner peripheral surface of housing 7, causes lubricant oil to flow and the inner space of circulation through housing 7, thereby comprises that the interior pressure balance of bearing of bearing play is suitably kept.In addition; Lubricant oil through bearing interior space do not expect flow; For example, the phenomenon that the pressure of lubricant oil becomes negative pressure partly can be prevented from, with the formation that the bubble that negative pressure is associated occurs, oil leak that bubble causes with problem such as vibration occurs and be overcome.

Although the first embodiment of the present invention as above has been described, the invention is not restricted to this embodiment, can be applicable to other structure.

Fig. 7 shown second embodiment's hydrodynamic bearing device 1 '.Hydrodynamic bearing device 1 shown in Figure 7 ' structure and first embodiment's the structure difference of hydrodynamic bearing device 1 be: the shape of axial region 2 has invariable diameter; Housing 7 is bottom cylindrical bodys.Therefore, only between the lower end surface 9a1 of thrust bearing surface 7a that side sections (side portion) 7g of housing 7 is provided with and hub portion on the other side 9, form the thrust-bearing gap.Note that the parts and the element that have same configuration and a function with first embodiment represent with same reference numbers, and omitted related description.

Constitute above-mentioned hydrodynamic bearing device 1 ' housing 7 comprise cylindrical side part 7g and bottom 7h, aforementioned side sections 7g is provided with thrust bearing surface 7a in the top, aforementioned bottom 7h is arranged on the lower end of side sections 7g.Side sections 7g and bottom 7h form through forging integrally.

Equally, in the present embodiment, the axial rings chute 7d of lubricant oil on the inner peripheral surface that is arranged on housing 7 flows and the inner space of circulation through housing 7.Promptly; The downward flows of lubricant oil between the surperficial 8a of the inner peripheral surface of bearing housing 8 and the external peripheral surface 2a of axial region 2; And the axial clearance → upper-end surface 8d between the upper-end surface 7h1 of lower end surface 8c and the bottom 7h of stream through bearing housing 8 and the passage of the axial clearance between the 9a1 of lower end surface, so that dragged the into radial bearing gap of the first radial bearing part R1 once more.Therefore, the interior pressure balance of bearing that comprises the bearing play is suitably kept.

Fig. 8 has shown the hydrodynamic bearing device 21 according to the 3rd embodiment.In the present embodiment, rotating member 22 comprises axial region 22a and integrally and independently is arranged on the flange portion 22b of the lower end of axial region 22a.The sealing component 29 of substantial cylindrical is fixed on the inner peripheral surface of upper end part of housing 27.Sealing component 29 forms seal space S2, and the top of the radial dimension of seal space S2 between the external peripheral surface 22a1 of inner circumferential surface 29a and axial region 22a on the other side increases gradually.

Housing 27 is metal forging article, has the overall structure of cylindrical side part 27a and side sections 27a, and comprises the bottom 27b of the lower limb that is positioned at side sections 27a.Although not shown, for example, on the upper-end surface 27b1 of the bottom of housing 27 27b, form spiral dynamic pressure groove, as thrust bearing surface.In addition, circumferential groove (circumferentialgroove) 8d1 that divides upper-end surface 8d diametrically is formed on the whole circumference of upper-end surface 8d of bearing housing 8, and a plurality of radial groove 8d2 form from this circumferential groove 8d1 towards the inner peripheral surface side.

When rotating member 22 rotations; The thrust-bearing gap of thrust-bearing part T11 is formed between the upper-end surface 22b1 of lower end surface 8c and flange portion 22b of bearing housing 8, and the thrust-bearing gap of thrust-bearing part T12 is formed between the lower end surface 22b2 of upper-end surface 22b1 and flange portion 22b of bottom 27b of housing 27.

Equally in the present embodiment, the axial rings chute 27d of lubricant oil on the inner peripheral surface that is arranged on housing 27 flows and the inner space of circulation through housing 27.Promptly; The downward flows of lubricant oil between the surperficial 8a of the inner peripheral surface of bearing housing 8 and the external peripheral surface 22a1 of axial region 22; And the circumferential groove 8d1 of the upper-end surface 8d of dynamic pressure groove → bearing housing 8 of the lower end surface 8c of the axial clearance → bearing housing 8 between the upper-end surface 7b1 of lower end surface 8c and the bottom 27b of stream through bearing housing 8 and the passage of radial groove 8d2, so that dragged the into radial bearing gap of the first radial bearing part R1 once more.Therefore, the interior pressure balance of bearing that comprises the bearing play is suitably kept.

Fig. 9 shown hydrodynamic bearing device 21 according to the 4th embodiment '.Hydrodynamic bearing device 21 shown in Figure 9 ' structure and the 3rd embodiment's the difference of structure of hydrodynamic bearing device 1 be: sealing component 29 integrally forms with the side sections 27a of housing 27, and the bottom 27b of housing 27 is independent of side sections 27a and is fixed on the inner circumferential surface 27c1 of lower end of side sections 27a.Note that the parts and the element that have same configuration and a function with the 3rd embodiment represent with same reference numbers, and omitted related description.

Equally, in the present embodiment, the circulating tanks 27d that lubricant oil is provided with on the inner peripheral surface of housing 27 flows and the inner space of circulation through housing 27.Therefore, the interior pressure balance of bearing that comprises the bearing play is suitably kept.

In addition, although not shown, the present invention also can be applicable to such structure, and housing 27 is at both ends open, and sealing component 29 and bottom 27b form and be separately fixed at inner peripheral surface and the inner peripheral surface of lower end of the upper end of housing 27 independently.

(first to the 4th embodiment) in the above-described embodiments shown that as an example hard relatively metal such as stainless steel forms housing 7 (27) situation through for example forging.Yet the present invention also can be applicable to other situation, for example forms the situation of housing 7 (27) through soft relatively metals such as forging brasses.

In addition, in above-mentioned example embodiment, the axial rings chute 7d (27d) that is formed on the inner peripheral surface of housing 7 (27) has the triangular-section, still, certainly uses other groove shape (sectional shape of groove).This is because be used as plastic working/plasticity treated side through the inner peripheral surface that forges the circulating tanks 7d (27d) that forms; And the roughness on its surface is fine; Therefore; Even the sectional shape difference can cause the difference of the mobile difficulty or ease of lubricant oil, also can guarantee the smooth circulation of fluid in circulating tanks 7d (27d).In addition, based on same cause, the quantity of circulating tanks 7d (27d) is not limited to illustrated three, can be provided with two, four or more a plurality of.

In addition, in the above-described embodiments, be used for producing in each bearing play dynamic pressure effect dynamic pressure generating section (for example, dynamic pressure groove 8a1,8a2) be arranged on each bearing play in the relative component side of rotating member 3, still, also can be arranged on rotating member 3 sides.For example; Be arranged on the formation dynamic pressure groove 8a1 on the surperficial 8a of inner peripheral surface of bearing housing 8, the external peripheral surface 2a that the zone of 8a2 and the zone that is arranged on the formation dynamic pressure groove of lower end surface 8c also can be arranged on relative axial region 2 (22a) go up and the upper-end surface 10a of flange portion 10 (22b) on.Therefore, the whole surface of bearing housing 8 can be made into level and smooth surface, there is no need the moulding section corresponding to circulating tanks 7d, dynamic pressure groove 8a1 etc. is set in forming die, and this can further simplify and reduce the cost of mould.

In addition; In the above-described embodiments, as the hydraulic bearing that constitutes radial bearing part R1, R2 and thrust-bearing part T1, T2, used its dynamic pressure generating section to comprise the signal bearing of herringbone for example or spiral dynamic pressure groove; But the structure of dynamic pressure generating section is not limited thereto.Radial bearing part R1, the example of R2 comprise leafy bearing (multilobe bearing), step bearing (stepbearing), conical bearing (taper bearing), sharp flat bearing (taper flat bearing) etc.

In addition, although not shown, for example; In being used as the zone of thrust bearing surface; Among thrust-bearing part T1, the T2 one or two also can be made up of such bearing, and this bearing comprises a plurality of dynamic pressure grooves with radial groove shape that are provided at predetermined intervals in a circumferential direction, promptly; So-called step bearing, so-called waveform bearing (wave bearings, its step is a waveform) etc.

In addition, in the above-described embodiments, the situation that radial bearing part R1, R2 and thrust-bearing part T1, T2 are made up of hydraulic bearing has been described, still, they also can be made up of other bearing.For example; The so-called cylindrical bearing that can constitute by surperficial 8a as the inner peripheral surface of the bearing housing 8 of radial bearing surface; Perfect round-shaped external peripheral surface 2a through the axial region 2 relative with this inner circumferential surface; So-called cylindrical bearing is made with perfect circular inner circumferential surface, and does not have dynamic pressure groove 8a1, dynamic pressure generating sections such as 8a2.Replacedly, thrust-bearing part T1, T2 also can be made up of pivot bearing (pivotbearing).Certainly, above-mentioned mechanical axis holds fractional t1, and such structure of T2 also may be used on thrust-bearing part T11, T12.

In addition; In the above-described embodiments; As an example, lubricant oil is as the fluid that forms lubricant film between fill fluid bearing means 1 (21) inside and radial bearing gap, bearing housing 8 and the axial region 2 between bearing housing 8 and axial region 2 or in the thrust-bearing gap between housing 7 and the rotating member 3 (hub portion 9).Yet, can use other fluid that can in each bearing play, form lubricating film, for example can use gas, magnetic fluid etc. such as air to have mobile oiling agent or lubricating grease and other.

Following with reference to the figure 10-13 explanation fifth embodiment of the present invention.

Figure 10 summarily shows the example of the information equipment of the dynamic pressure bearing device 101 that is integrated with fifth embodiment of the invention with spindle motor.This spindle motor is used for disc drive units such as HDD; And comprise hydrodynamic bearing device 101 and electric machine support 106; Hydrodynamic bearing device 101 supports rotating member 103 rotationally; Rotating member 103 comprises the axial region 2 that non-contact is supported, for example, and diametrically across both sides, gap stator coil 104 respect to one another and rotor magnet 105.Stator coil 104 is attached on the outer circumferential face of electric machine support 106, and rotor magnet 105 is attached on the outer circumferential face of rotating member 103.The housing 107 of hydrodynamic bearing device 101 is fixed on the inner peripheral surface of electric machine support 106.Disc-shaped information recording mediums such as one or more disks (being designated hereinafter simply as disk) are maintained on the rotating member 103.In the spindle motor of so constructing; When exciting stator coil 104; The electromagnetic force rotary rotor magnet 105 that produces between stator coil 104 and the rotor magnet 105, therefore, rotating member 103 rotates with axial region 102 with the disk D that is rotated member 103 maintenances.

Figure 11 shows dynamic pressure bearing device 101.Hydrodynamic bearing device 101 by housing 107, be fixed to the bearing housing 108 of housing 107 and constitute as the rotating member 103 that rotates with respect to housing 107 and bearing housing 108 of primary component.Note that for illustrative purposes in following explanation, in the open part of the housing 107 that two axial ends form, be known as downside by a side of lid member 111 sealings, a side relative with sealed sides is known as upside.

Rotating member 103 constitutes by for example covering at the hub portion 109 of the opening side of housing 107 and the axial region 102 of the inner peripheral surface that inserts bearing housing 108.

Hub portion 109 comprises the disk segment 109a of the opening side (upside) of covering shell 107, from the outer circumferential face of disk segment 109a axially to the column part 109b that extends below, disk supporting plane 109c be arranged on the edge 109d on the outer circumferential face of column part 109b.The disk that does not show is placed on the outer circumferential face of disk segment 109a and is installed on the disk supporting plane 109c.In addition, disk is maintained on the hub portion 109 through the suitable holding device (clamp holder etc.) that does not show.

Axial region 102 in the present embodiment integrally forms with hub portion 109, comprises the independently flange portion 110 that prevents slippage in the lower end of axial region 102.Flange portion 110 is made of metal, and is fixed on the axial region 102 through means such as be threaded.

For example, bearing housing 108 is formed by the porous body that comprises sintering metal cylindrically, particularly comprises with the sintering metal porous body of copper as main component.

Dynamic pressure groove as radial dynamic pressure generation portion is formed on the inner circumferential surface 108a Zone Full or part area of bearing housing 108.In the present embodiment, for example shown in figure 12, axially independently be formed with two zones on the position, on these two zones, be furnished with a plurality of dynamic pressure groove 108a1, the 108a2 of herringbone (herringbone).In the zone that forms dynamic pressure groove 108a1, dynamic pressure groove 108a1 axially is formed asymmetrically with respect to axle center m (axle center in the zone between the upper and lower tipper), and the axial dimension X1 of axle center m upper area is greater than the axial dimension X2 of axle center m lower zone.

Although not shown, for example, on the annular region of the lower end surface of bearing housing 108 108c all or part of, be formed with the zone of arranging a plurality of spirality dynamic pressure grooves on it, as thrust dynamic pressure generation portion.This zone that forms the dynamic pressure groove is relative with upper-end surface 110a as the flange portion 110 of thrust bearing surface, and when axial region 102 (rotating member 103) rotates, is formed with the thrust-bearing gap (seeing Figure 11) of the formation second thrust-bearing part T22 between zone and the upper-end surface 110a of dynamic pressure groove above that.

Housing 107 by stainless steel and other metal materials for example to form cylindrically.Housing 107 be shaped as all openings of two axle heads, and another is distolateral by cover component 111 sealings.The all or part of thrust bearing surface 107a that is provided with of the annular region of an end face side (upper-end surface).In the present embodiment, for example shown in figure 13, the zone that is furnished with a plurality of spirality dynamic pressure groove 107a1 on it is formed on the thrust bearing surface 107a, as thrust dynamic pressure generation portion.Thrust bearing surface 107a (forming the zone of dynamic pressure groove 107a1 on it) is relative with the lower end surface 109a1 of the disk segment 109a of hub portion 109.When rotating member 103 rotations, the thrust-bearing gap of the first thrust-bearing part T21 that will describe after a while is formed between thrust bearing surface 107a and the lower end surface 109a1 (referring to Figure 11).

Another distolateral cover component 111 of seal casinghousing 107 is formed by metallic material or resin material, and it is last to be fixed to shoulder (shoulder) 107b of inner peripheral surface side of the other end that is arranged on housing 107.Here; Be not limited to concrete fixing means; For example, can select bonding (comprise and freely boning and the pressure fitted bonding), pressure fitted, welding bonding (for example ultrasonic welding), welding means such as (for example, laser beam welding) suitably according to combination and required installation strength, the sealability etc. of material.

The external peripheral surface 108b of bearing housing 108 is fixed on the inner circumferential surface 107c of housing 107, for example, fixes through bonding (comprise and freely boning and the pressure fitted bonding), pressure fitted, welding bonding or other suitable means.

On the outer circumferential face of housing 107, be formed with conical seal (contact) face 107d, the diameter of conical seal (contact) face 107d increases towards the top gradually.Between the inner circumferential surface 109b1 of conical seal (contact) face 107d and column part 109b, be formed with ring packing space S 3, the radial dimension of ring packing space S 3 reduces to the top from the sealed sides of housing 107 gradually.When axial region 102 rotates with hub portion 109, the outer diameter side circulate in the thrust-bearing gap of the sealing space S 3 and the first thrust-bearing part T21.

In addition, be formed with cylindrical external peripheral surface 107e at the lower end of the outer circumferential face of housing 107, this cylindrical external peripheral surface 107e has invariable diameter.This cylindrical external peripheral surface 107e is fixed on the inner circumferential surface 106a of electric machine support 106 through bonding, pressure fitted or other means.Therefore, dynamic pressure bearing device 101 is integrated in the motor.

The inside of dynamic pressure bearing device 101 comprises the inner aperture (aperture of porous body tissue) of bearing housing 108 being full of lubricant oil.The pasta of lubricant oil is always maintained in the seal space S3.

When axial region 102 (rotating member 103) rotates; (form dynamic pressure groove 108a1 at this regional upper position and lower position, 108a2) the external peripheral surface 102a with axial region 102 is relative in the both sides in radial bearing gap as the zone of the radial bearing surface of the inner circumferential surface 108a of bearing housing 108.In addition, when axial region 102 rotations, the lubricant oil of top, radial bearing gap is pushed to dynamic pressure groove 108a1, the axle center m side of 108a2, and the pressure of lubricant oil increases.The first radial bearing part R21 and the second radial bearing part R22 are configured, and the first radial bearing part R21 and the second radial bearing part R22 support axial region 102 through the dynamic pressure effect of dynamic pressure groove with the non-contact supporting way.

Simultaneously; Through the dynamic pressure effect of dynamic pressure groove, form lubricating oil oil film in each in the thrust-bearing gap between the lower end surface 108c (forming the zone of dynamic pressure groove) of thrust-bearing gap between the lower end surface 109a1 (disk segment 109a) of thrust bearing surface 107a of housing 107 (forming the zone of dynamic pressure groove 107a1) and hub portion on the other side 109 and bearing housing 108 and the upper-end surface 110a of flange portion on the other side 110.In addition, the first thrust-bearing part T21 and the second thrust-bearing part T22 are configured, and the first thrust-bearing part T21 and the second thrust-bearing part T22 support rotating member 103 through the pressure of these oil films with the non-contact supporting way on thrust direction.

The method example of making the housing 107 that constitutes dynamic pressure bearing device 101 is described below with reference to Figure 14.

In the present embodiment, make housing 107 with following three steps: the step of moulding external peripheral surface (D); The step of moulding inner circumferential surface (E); The step of moulding thrust bearing surface (F).

(D) step of moulding external peripheral surface

At first; Cold forging is made (compression) and is cut into the cylindricality base material (columnar blank material) that suitable length prepares through stretching wire rod and with it in a pair of mould that does not show, forms the external peripheral surface (sealing surface 107d and cylindrical external peripheral surface 107e) of housing 107.The example that note that suitable cold forging making process not only comprises aforesaid upset(ting) method (upsetting), and comprises combination and various other forming method of forward extrusion method (forward extrusion), forward extrusion method and upset(ting) method.

(E) step of moulding inner circumferential surface

Secondly, make the inner circumferential surface 107c of the housing 107 that case material 107 ' formation will form, at case material 107 ' comprise the sealing surface 107d and the cylindrical external peripheral surface 107e that are formed on the outer circumferential face through cold forging.Shown in figure 14; Employed mould by mould 116 for example, upper punch (upperpunch) 107 ' and low punch (bar) 118 constitute; Aforementioned mould 116 constraint case materials 107 ' the mould 16 of external peripheral surface; Aforementioned upper punch 107 ' from the thrust bearing surface 107a side that will form retrain in the axial direction case material 107 '; Aforementioned low punch 118 has the molded surface 118a corresponding to the inner circumferential surface 107c of the housing that will form 107, and molded surface 118a is arranged on the outer circumferential face of low punch 118.Shown in figure 14 equally; Under the restrained state of case material 107 ' radial and axial; Bar 118 (on the diagram direction of arrow) rises, pass from lower end side (side opposite) towards upper end side (thrust bearing surface 107a side) with thrust bearing surface 107a side case material 107 ' inner peripheral surface.Therefore, case material 107 ' at axial both ends open, make the shape of copy molded surface 118a (the stationary plane 107c of manufactured good) form case material 107 ' inner peripheral surface.In the present embodiment, form the inner circumferential surface 107c and the shoulder 107b of manufactured good simultaneously through using bar 118, bar 118 also has the moulding section 118b corresponding to shoulder 107b except having the part corresponding to the molded surface 118a of inner circumferential surface 107c.

As stated; Before the inner peripheral surface of inner circumferential surface 107c, carry out the forging of the external peripheral surface of housing 107; Therefore, when exerting pressure, can avoid case material 107 ' the distortion of not expecting; Particularly can avoid the distortion of not expecting of thick wall part (upside among the figure), can accurately keep the shape of the sealing surface 107d that is provided with on the outer circumferential face.

(F) step of moulding thrust bearing surface

At above-mentioned steps (D), (E) afterwards, make the thrust bearing surface 107a of the housing 107 that case material 107 ' formation will form through cold forging.In this forming step, for example, although not shown, the mould of use is made up of the lower end surface of mould shown in Figure 14 116 and bar 118 and upper punch (upper punch) 117, and they constitute the molded surface corresponding with the thrust bearing surface 107a of the housing that will form 107.Retrain diametrically with mould 116 and bar 118 case material 107 firmly ' state under, upper punch 117 (on the diagram direction of arrow) descends, through the molded surface (not shown) that applies predetermined pressure upper punch 117 push case material 107 ' the upper end.Therefore, case material 107 ' the shape of upper-end surface copy molded surface (the thrust bearing surface 107a of manufactured good) form.In addition, in the present embodiment, although not shown; Used dynamic pressure generating section; This dynamic pressure generating section has preformed groove pattern (groovepattern) corresponding to dynamic pressure groove 107a1 on the molded surface of upper punch 117, therefore, forms the shape of dynamic pressure groove 107a1 simultaneously.

In above-mentioned steps (D) to (F) afterwards, housing 107 is formed manufactured good (with reference to Figure 11).

As long as use above-mentioned production method to make housing 107, thrust bearing surface 107a can be accurate to 20 μ m or littler (10 μ m or littler ideally) with respect to the perpendicularity of inner circumferential surface 107c or external peripheral surface 107e.

In addition, sealing surface 107d can be accurate to 20 μ m or littler (10 μ m or littler ideally) with respect to the coaxality of inner circumferential surface 107c or external peripheral surface 107e.

In addition, external peripheral surface 107e can be accurate to 20 μ m or littler (10 μ m or littler ideally) with respect to the coaxality of inner circumferential surface 107c.

In addition, thrust bearing surface 107a can be accurate to 20 μ m or littler (10 μ m or littler ideally) with respect to the perpendicularity of the axis of inner sealing surface 107d.

In addition, sealing surface 107d departing from (runout) and can be accurate to 20 μ m or littler (10 μ m or littler ideally) with respect to the axis of inner circumferential surface 107c.

In addition, the profile of sealing surface 107d (profile) can be accurate to 20 μ m or littler (10 μ m or littler ideally).

Suppress (form accuracy) in above-mentioned scope through these geometrical deviations between each surface that will constitute housing 107, the dynamic pressure bearing device 101 that just can realize having improved support performance, running accuracy, sealability etc. maybe can realize comprising the motor of such dynamic pressure bearing device 101.

Note that above-mentioned steps (D) only is the example of the mould that constituted to (F), also can use other mould structure, as long as each form accuracy (perpendicularity, coaxality etc.) of molding product can be set in the above-mentioned scope.

Below with reference to the Figure 15 and the 16 explanation sixth embodiment of the present invention.The explanation that note that the part identical with the 5th embodiment is omitted.

Figure 15 shows the example of the information equipment of the dynamic pressure bearing device 121 that is integrated with sixth embodiment of the invention with spindle motor.This spindle motor also is used for disc drive units such as HDD; And comprise dynamic pressure bearing device 121 and electric machine support 126; Dynamic pressure bearing device 121 supports rotating member 123 rotationally, and rotating member 123 comprises the axial region 122 that non-contact is supported, for example; Diametrically across both sides, gap stator coil respect to one another 124 and rotor magnet 125, electric machine support 126 is fixed on the outer circumferential face of housing 127 of dynamic pressure bearing device 121.

Figure 16 shows dynamic pressure bearing device 121.This dynamic pressure bearing device 121 mainly by housing 127, be fixed on bearing housing 128 on the inner peripheral surface of housing 127, insert at axial region 122 that rotating member 123 and the bearing housing 128 with respect to housing 127 rotations constitutes under the state of inner peripheral surface of bearing housings 128.

Rotating member 123 mainly is made up of axial region 122 and hub portion 129.In the middle of them, axial region 122 for example forms the shape shaft with homogeneous diameter by stainless steel and other metal materials.

In the present embodiment, hub portion 129 forms through penetrating mold forming (injection-molding) resin material, uses axial region 122 as insert.Disk supporting plane 129c and edge 129d on column part 129b that shown in figure 16, hub portion 129 comprises the disk segment 129a of the opening side (upside among the figure) of covering shell 127, axially extend downwards from the outer circumferential face of disk segment 129a and the outer circumferential face that is arranged on column part 129b.Note that hub portion 129 can for example be made of metal.In this case, hub portion 129 can integrally form with axial region 122.

Housing 127 is forging products of being processed by metallic material (for example stainless steel), and it is cylindrical to form the bottom.Housing 127 comprises cylindrical side part 127a and the bottom 127b that is arranged on the lower end of side sections 127a.Bottom 127b and side sections 127a integrally form.

Thrust bearing surface 127c is formed on annular region all or part of of the end face (upper-end surface) on the opening side of housing 127.Although not shown, for example, on thrust bearing surface 127c, be formed with zone as thrust dynamic pressure generation portion, the dynamic pressure groove is with identical shaped layout shown in Figure 13 in this zone.The lower end surface 129a1 of the disk segment 129a of thrust bearing surface (forming the zone of dynamic pressure groove) 127c and hub portion 129 is relative; When axial region 122 (rotating member 123), thrust bearing surface 127c forms the thrust-bearing gap (referring to Figure 16) of the thrust-bearing part T31 between thrust bearing surface 127c and lower end surface 129a1 of explanation after a while.

On the outer circumferential face on the top of side sections 127a, form conical seal (contact) face 127e, the diameter of conical seal (contact) face 127e increases towards the top gradually.At sealing surface 127e be arranged on and form cone seal space S 4 between the inner circumferential surface 129b1 of the column part 129b on the hub portion 129, the diameter of cone seal space S 4 reduces towards the top gradually.When axial region 122 rotates with hub portion 129, the outer diameter side circulate in the thrust-bearing gap of seal space S4 and thrust-bearing part T31.In addition; On the inner peripheral surface of the lower end of the column part 129b of hub portion 129, be attached with blocking element (latch member) 130; Blocking element 130 engages with housing 127 in the axial direction, and when axial region 122 (rotating member 123) blocking element 130 locking axial regions 122 when relatively moving upwards in the axial direction.

The porous body (porous body) that bearing housing 128 is processed by non-porous body of for example metal (non-porous body) or sintering metal forms, and particularly by comprising that the porous body of processing as the sintering metal of main component with copper forms, bearing housing 128 is cylindrical.Through bonding (comprise and freely boning and the pressure fitted bonding), pressure fitted, welding bonding or other assembling means, bearing housing 128 is mounted to the precalculated position of the inner circumferential surface 127d of housing 127.

In the present embodiment, as stated, only between the lower end surface 129a1 of the thrust bearing surface 127c of housing 127 and disk segment 129a on the other side, form the thrust-bearing gap, the thrust-bearing gap is not formed on the lower end side of axial region 122.Therefore, have a plurality of dynamic pressure grooves shown in figure 12 on the inner circumferential surface 128a of the bearing housing 128 among the 6th embodiment, simultaneously, the upper-end surface of bearing housing 128 and lower end surface are the even surfaces with dynamic pressure groove.

In the dynamic pressure bearing device 121 that so constitutes; The inner space that comprises the housing 127 in seal space S4 and thrust-bearing gap is full of lubricant oil; When axial region 122 (rotating member 123) rotates, relative in both sides, radial bearing gap as the external peripheral surface 122a of the zone (zone of position, upper and lower) of the radial bearing surface of the inner circumferential surface 128a of bearing housing 128 and axial region 122.When axial region 122 rotation, the lubricant oil of top, radial bearing gap the dynamic pressure groove axially on be pushed to central side, the pressure of lubricant oil increases.The first radial bearing part R21 and the second radial bearing part R22 are constituted respectively, and the first radial bearing part R21 and the second radial bearing part R22 support axial region 122 through the dynamic pressure effect of dynamic pressure groove with the non-contact supporting way.

Simultaneously, through the dynamic pressure effect of dynamic pressure groove, also form the oil film of lubricant oil in the thrust-bearing gap between thrust bearing surface (forming the zone of the dynamic pressure groove) 127c of the lower end surface of hub portion 129 129a1 and housing on the other side 127.Thrust-bearing part T31 is configured, and thrust-bearing part T31 supports axial region 122 (rotating member 123) through the pressure of this oil film with the non-contact supporting way on thrust direction.

For example also make housing 127 in the present embodiment: the step of moulding external peripheral surface (D) with three steps; The step of moulding inner circumferential surface (E); Step (F) with the moulding thrust bearing surface.Although it is not shown; For example; Difference is: in the step (E) of moulding inner circumferential surface; In the opening operation of the hole of the inner peripheral surface of carrying out case material, the direction of perforate is axially towards a side relative with thrust bearing surface 127c side (side opposite with thrust bearing surface 127c side) from thrust bearing surface 127c.

Through after the above-mentioned steps, be formed (referring to Figure 16) as the housing 127 of manufactured good.

As long as use above-mentioned production method to make housing 127, thrust bearing surface 127c can be accurate to 20 μ m or littler (10 μ m or littler ideally) with respect to the perpendicularity of inner circumferential surface 127d or external peripheral surface 127f.

In addition, sealing surface 127e can be accurate to 20 μ m or littler (10 μ m or littler ideally) with respect to the coaxality of inner circumferential surface 127d or external peripheral surface 127f.

In addition, external peripheral surface 127f can be accurate to 20 μ m or littler (10 μ m or littler ideally) with respect to the coaxality of inner circumferential surface 127d.

In addition, thrust bearing surface 127c can be accurate to 20 μ m or littler (10 μ m or littler ideally) with respect to the perpendicularity of the axis of sealing surface 127e.

In addition, sealing surface 127e departing from (runout) and can be accurate to 20 μ m or littler (10 μ m or littler ideally) with respect to the axis of inner circumferential surface 127d.

In addition, the profile of sealing surface 127e can be accurate to 20 μ m or littler (10 μ m or littler ideally).

Suppress (form accuracy) in above-mentioned scope through these geometrical deviations between each surface that will constitute housing 127, the dynamic pressure bearing device 121 that just can realize having improved support performance, running accuracy, sealability etc. maybe can realize comprising the motor of such dynamic pressure bearing device 121.

Although the of the present invention the 5th and the 6th embodiment as above has been described, has the invention is not restricted to these embodiments.

In the above-described embodiments, housing 107 (127) only is an example through forging method, situation about being formed by relative rigidity metals such as for example SUS.Yet the present invention also can be applicable to through forging method, by other situation of soft metal relatively such as for example brass.

In addition, in the above-described embodiments, as constituting radial bearing part R21; R22 and thrust-bearing part T21, T22, the hydraulic bearing of T31; For example, used a kind of exemplary bearings, the dynamic pressure generating section in this exemplary bearings comprises herringbone or spiral dynamic pressure groove; But the structure of dynamic pressure generating section is not limited thereto.Radial bearing part R21, the example of R22 comprise leafy bearing (multilobebearing), step bearing (step bearing), conical bearing (taper bearing), sharp flat bearing (taper flat bearing) etc.

In addition, although not shown, in being used as the zone of thrust bearing surface; Thrust-bearing part T21, T22, among the T31 one or all also can constitute by for example such bearing; This bearing comprises a plurality of dynamic pressure grooves with radial groove shape that are provided at predetermined intervals in a circumferential direction; That is, so-called step bearing, so-called waveform bearing (wave bearings, its step is a waveform) etc.

In addition, in the above-described embodiments, radial bearing part R21 has been described, R22 and thrust-bearing part T21, T22, the situation that T31 is made up of hydraulic bearing, still, they can be made up of other bearing.For example; The so-called cylindrical bearing that can constitute by the inner circumferential surface 108a of the bearing housing 108 (128) that is used as radial bearing surface; Perfect round-shaped external peripheral surface 102a through the axial region 102 relative with this inner circumferential surface; This so-called cylindrical bearing is made with perfect circular inner circumferential surface, and does not have dynamic pressure groove 108a1, dynamic pressure generating sections such as 108a2.

In addition; In the above-described embodiments; As an example, lubricant oil is as between radial bearing gap, bearing housing 108 and the axial region 102 between fill fluid bearing means 101 (121) inside, bearing housing 108 and the axial region 102 or thrust-bearing gap and the fluid that forms lubricant film between housing 107 and the rotating member 103 (hub portion 109).Yet, can use other fluid that can in each bearing play, form lubricating film, for example can use gas, magnetic fluid (magnetic fluid) etc. such as air to have mobile oiling agent or lubricating grease.

Claims (5)

1. hydrodynamic bearing device, it comprises: housing, this housing form cylindrical and have and be fixed to the stationary plane on the inner peripheral surface of housing to the external peripheral surface of bearing housing; Bearing housing, this bearing housing are fixed on the stationary plane of housing; Rotating member, this rotating member is with respect to bearing housing and housing rotation; And the radial bearing part, the lubricating film that this radial bearing partly is utilized in the fluid that produces in the radial bearing gap between rotating member and the bearing housing carries out the non-contact supporting to rotating member diametrically;

Said hydrodynamic bearing device is characterised in that,

Rotating member is made up of the hub portion of the opening side that is arranged on housing and the axial region of the inner peripheral surface that inserts bearing housing; At the thrust bearing surface that is formed at the end face on the opening side of housing; And between the lower end surface of the hub portion relative, be formed with the thrust-bearing gap with this bearing surface

On the inner peripheral surface of housing, be formed with the axial rings chute, this axial rings chute is used to make two end faces of bearing housing to form the circulation connection,

Be fixed at bearing housing under the state of stationary plane of housing, the lower end of circulating tanks and the lower end surface of bearing housing form circulate, and its upper end forms circulate with the upper-end surface and the thrust-bearing gap of bearing housing, and,

Stationary plane and circulating tanks all pass through to forge and form.

2. hydrodynamic bearing device as claimed in claim 1, wherein fluid circulates between the inside at the other end place of housing and seal space through circulating tanks.

3. a spindle motor that is used for disk unit has the hydrodynamic bearing device described in claim 1 or 2.

4. the production method of a hydrodynamic bearing device, said hydrodynamic bearing device comprises: housing, this housing form cylindrical and are formed with and be fixed to the stationary plane on the inner peripheral surface of housing to the external peripheral surface of bearing housing; Bearing housing, this bearing housing are fixed on the stationary plane of housing; Rotating member, this rotating member is with respect to bearing housing and housing rotation; And the radial bearing part, the lubricating film that this radial bearing partly is utilized in the fluid that produces in the radial bearing gap between rotating member and the bearing housing carries out the non-contact supporting to rotating member diametrically;

Rotating member is made up of the hub portion of the opening side that is arranged on housing and the axial region of the inner peripheral surface that inserts bearing housing; At the thrust bearing surface that is formed at the end face on the opening side of housing; And between the lower end surface of the hub portion relative, be formed with the thrust-bearing gap with this bearing surface, on the inner peripheral surface of housing, be formed with the axial rings chute; This axial rings chute is used to make two end faces of bearing housing to form the circulation connection

Be fixed at bearing housing under the state of stationary plane of housing, the lower end of circulating tanks and the lower end surface of bearing housing form circulate, and its upper end forms circulate with the upper-end surface and the thrust-bearing gap of bearing housing,

The production method of said hydrodynamic bearing device is characterised in that,

Through the forging molding housing time,

Forge mould with Slot shaping part is provided, and this Slot shaping partial parallel extends in the stroke direction of said mould, and this Slot shaping partly is used to forge circulating tanks.

5. the production method of hydrodynamic bearing device as claimed in claim 4; Wherein on the forge mould that is provided with the Slot shaping part, be provided for forming the face moulding section of stationary plane, utilize these Slot shaping parts and face moulding section to form circulating tanks and stationary plane simultaneously through forging.

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