Abstract: There is provided a fluid dynamic bearing assembly including: a sleeve having a shaft insertedly mounted therein; and upper and lower radial bearing parts formed on at least one of an outer circumferential surface of the shaft and an inner circumferential surface of the sleeve, wherein a clearance between the lower radial bearing part and a surface disposed to face the lower radial bearing part is wider than a clearance between the upper radial bearing part and a surface disposed to face the upper radial bearing part.

Abstract: An example journal air bearing for a rotatable shaft of an air cycle machine includes a top foil configured to receive a rotatable shaft, and an intermediate foil radially outboard the top foil. A journal sleeve is radially outboard the intermediate foil. The top foil and the intermediate foil establish apertures configured to communicate fluid between a first position radially inboard the top foil and a second position radially outboard the intermediate foil.

Abstract: Provided is a fluid bearing device with a hub part having high molding precision and dimensional stability and capable of being produced at low cost. An annular gate (14) is formed at a portion of a cavity (15) corresponding to an outer peripheral edge portion of a lower end surface (10c1) of a flange part (10c), and a molten resin (P) is filled into the cavity (15) through the annular gate (14) to form a hub part (10) made of resin. The hub part (10) molded by the injection molding exhibits a radial resin orientation through an entire periphery thereof. Further, an annular gate trace (16) is formed at the outer peripheral edge portion of the lower end surface (10c1) of the flange part (10c) of the hub part (10).

Abstract: A gas bearing (100) having pressurised axially extending chambers (110) in a housing (102) having a shaft bore (104) therein, the axially chambers (110) being in fluid communication with a bearing surface (108) that defines the bore via laser-drilled capillaries (118). The end (122) of each laser-drilled capillary at the bearing surface (108) is flared such that the narrowest portion of the capillary is set back from the bearing surface (108). This shape can ensure that the load carrying function of the bearing (100) does not fail during shaft eccentricity by ensuring that pressure restriction must happen within the capillary and not the gap being shaft and bearing surface. The bearing surface may face in an axial and/or radial direction with respect to the shaft. The axial chambers may be pressurised axially such that the outer circumference of the housing is unbroken and hence usable for other purposes.

Abstract: This invention relates to bearings, and more specifically is directed to active hydrostatic bearings destined for large heavily loaded reciprocating internal combustion engines, like ultra high compression ratio Diesel cycle engines, and homogeneous charge compression ignition (HCCI) and detonation engines working on stoichiometric fuel/air mixture. A fluid handling system therefore, method and apparatus are also disclosed.

Abstract: A hydrodynamic bearing (1) for an internal combustion engine is composed of a sliding material whose average maximum roughness value leads an accelerated wear of the sliding material and an accelerated accommodation of a crankshaft during engine operation.

Abstract: A sliding radial bearing assembly for use on a rotating shaft in machinery where a fluid lubricant passes through the assembly to provide a lubricant film between stationary and rotating parts of the assembly. Any gaseous phase is allowed readily to escape from the assembly by providing a lubricant passage which exits close to the shaft, while a substantially non-gaseous film of liquid lubricant is maintained at the bearing interface.

Abstract: A system, method and means is provided for withstanding mechanical shock for use with fluid dynamic bearings. A sealing system is provided that withstands 1000 G shock events. In an aspect, a grooved pumping seal employed between a thrust plate and a shield, a thrust plate having spiral grooves, a fluid recirculation passageway, and a reservoir creates an asymmetric pressure gradient. In an aspect, fluid is retained and air is purged utilizing an enlarged fluid reservoir, axial channels and an angled fill hole. In an aspect, a shaft is attached to a top cover supplying radial stiffness, and an enlarged single-sided thrust plate improves dynamic parallelism.

Abstract: The invention relates to a fluid dynamic bearing system having a bearing bush and a shaft that are rotatable with respect to one another about a common rotational axis and form a bearing gap filled with bearing fluid between associated bearing surfaces. The bearing surfaces form at least one fluid dynamic radial bearing. A rotor component is disposed on the shaft. A stopper ring is disposed on the shaft or on the rotor component and adjoins the bearing bush, wherein a gap is formed between the mutually facing surfaces of the bearing bush and the stopper component that is filled with a bearing fluid and connected to the bearing gap and extends substantially in a radial direction. According to the invention, the surfaces of the bearing bush and/or the stopper component are formed such that the gap is tapered, narrowing radially outwards.

Abstract: An annular groove is provided to the rotary portion and/or the fixed portion in a bearing seal portion, and its cross section has a shape approximated by an arc. The annular groove is such that the relationship between the groove width W in a direction following the surface constituting a bearing seal portion and the groove depth Dg in a direction perpendicular to the surface constituting the bearing seal portion is Dg/W<0.4.

Abstract: A hydrostatic gas bearing capable of easily adjusting a clearance between a rotor and a radial bearing pad is provided. This hydrostatic gas bearing comprises a radial bearing pad radially supporting a rotor, a linear motion guide moving the radial bearing pad and a ball stud swingably coupling the radial bearing pad to the linear motion guide. The linear motion guide moves the radial bearing pad in a direction intersecting with a direction connecting the center of rotation of the rotor and the ball stud with each other. The quantity of adjustment in movement of the radial bearing pad caused by the linear motion guide is larger than the quantity of change in the clearance between the outer peripheral surface of the rotor and the radial bearing pad, whereby a small quantity of the bearing clearance can be precisely adjusted.

Abstract: A fluid dynamic bearing system that has a first bearing part and a second bearing part that is rotatable with respect to the first bearing part, both of which form a bearing gap filled with a bearing fluid between opposing bearing surfaces.

Abstract: A hydrodynamic type oil-impregnated sintered bearing includes a porous bearing body of sintered metal having a bearing surface opposed to a sliding surface of a rotating shaft, hydrodynamic pressure generating grooves slanting against an axial direction provided in the bearing surface, and lubricating oil or lubricating grease impregnated in pores inside the bearing body, wherein a rate of area of surface holes on the bearing surface is set within a range of 3%-15%, the surface holes being distributed substantially uniformly over the whole area of the bearing surface including areas of the hydronamic pressure generating grooves, wherein the lubricating oil or a base oil of the lubricating grease forms a lubricating film in a bearing clearance, and wherein the lubricating oil or a base oil of the lubricating grease is a lubricating oil selected from among mixtures of poly-?-olefin or hydrogenated compound thereof and a defined phosphoric ester.

Abstract: To increase fixation strength of a bearing sleeve with respect to a bottomed cylindrical housing, a fluid dynamic bearing device (1) is provided with a bottomed cylindrical housing (7), a bearing sleeve (8) fixed to an inner periphery thereof, and a shaft member (2) inserted along an inner periphery of the bearing sleeve (8). An adhesive pool (11) is provided between an inner peripheral surface (7a2) of a smaller diameter portion (7a) of the housing (7) and an outer peripheral surface (8d) of the bearing sleeve (8), which are opposed to each other. Further, an inner peripheral chamfer (7f) continuous with the adhesive pool (11) is provided on an inner peripheral portion of the housing (7), and a first tapered space (12) formed between the inner peripheral chamfer (7f) and the bearing sleeve (8) is sealed with an adhesive (13).

Abstract: A drivetrain for use with a power unit. The drivetrain may have a driving member, a driven member, and a sleeve disposed between the driving member and the driven member. The drivetrain may further have a first oil film bearing disposed between the sleeve and one of the driving member and the driven member.

Abstract: A fluid dynamic bearing motor is described. In one embodiment, the fluid dynamic bearing motor includes a base that has a bore hole and a liner secured within the bore hole. The fluid dynamic bearing motor also includes a rotor assembly that has a shaft, which is partially disposed within the liner and configured to rotate relative to the liner. A fluid dynamic bearing is disposed between the liner and the shaft to support this relative rotation.

Abstract: A device for axially conveying fluids, wherein the conveyor part thereof is entirely magnetically borne and the radial bearing thereof is provided with sufficient rigidity and efficiently dampened, whereby problems encountered when passing through critical speeds and the disadvantageous effects of hydrodynamic and mechanical imbalance of the rotor are avoided. The magnetic bearing is combined with a hydrodynamic bearing.

Abstract: Gas journal bearing systems are provided. An exemplary gas journal bearing system comprises a vortex generator, a housing and a journal. The vortex generator is operative to receive a flow of gas and to impart an angular acceleration to the gas. The housing is in fluid communication with the vortex generator, with housing having a first exhaust through which the gas is exhausted. The journal is supported within the housing by a vortex of the gas as the gas swirls along at least a portion of a length of the journal. Methods and other systems also are provided.

Abstract: A disk drive device includes: a hub on which a recording disk is to be mounted; a shaft; a sleeve configured to house the shaft and to be rotatable relatively with respect to the shaft; a radial space portion formed between the inner circumferential surface of the sleeve and the outer circumferential surface of the shaft; a radial dynamic pressure generating portion configured to generate radial dynamic pressure between at least part of the inner circumferential surface of the sleeve and the outer circumferential surface of the shaft in the radial space portion; and lubricant. The axial length of the radial dynamic pressure generating portion is formed to be longer than the diameter of the radial dynamic pressure generating portion such that radial dynamic pressure, which is defined with the axial length of the radial dynamic pressure generating portion and the diameter thereof being parameters, is greater than or equal to a predetermined minimum reference value.

Abstract: A system for supporting a rotating shaft, including a primary bearing configured to maintain the shaft within a predetermined range of operational shaft positions; a process fluid source; and a hydrostatic auxiliary bearing having an inner surface manufactured from a self lubricating composite material. The hydrostatic auxiliary bearing is fluidically coupled to the process fluid source and configured to use a pressurized process fluid provided by the process fluid source to maintain the shaft within the predetermined range of operational shaft positions when the primary bearing fails to maintain the shaft within the predetermined range of operational shaft positions when the primary bearing fails.

Abstract: A molding pin (23) is formed in a sectional shape of being held in contact at two points (contact points are denoted by P?) with an imaginary cylindrical surface (C?). As a result, an undercut of a fixation hole (21b1) is reduced or eliminated, and hence it becomes easier to process a die. Moreover, a corner portion (21d) between a cylindrical surface (21c) and the fixation hole (21b1) becomes obtuse, and hence the die becomes less liable to deform and break. Therefore, manufacturing cost of the die can be reduced, and hence cost reduction of the bearing device can be achieved.

Abstract: Provided is an aerostatic bearing spindle system using a unidirectional porous metal. The aerostatic bearing spindle system using a unidirectional porous metal may be used to serve as bearings in a region is in contact with the unidirectional porous metals when the unidirectional porous metals are rotated at a high speed, the unidirectional porous metals being manufactured with high porosity and directionality using the metallurgical method.

Abstract: As axis direction dimensions become smaller in HDD spindle motors as a result of thinner and more compact designs, there is a demand for hydrodynamic bearings with a long lifespan. As a means of solving this problem, a lubricant reservoir section is formed between a sleeve side surface and a cover side surface with a depth varying in a circumferential direction, lubricant is circulated in a bearing gap section, a sleeve end face gap section larger than a bearing gap between a sleeve end face and the cover, and a connecting channel, and the lubricant reservoir section and the sleeve end face gap section are connected via an introducing gap section having a bubble separation function.

Abstract: A hydrodynamic bearing (300) has a bearing surface adapted for receiving a shaft to rotate thereon. The bearing surface has a plurality of grooves (34) defined therein. The grooves are used for generating hydrodynamic pressure. A depth of each of the grooves is changed in a sloping trend along the extension direction of the groove.

Abstract: A maximum diameter (d) of each of surface openings formed in a bearing surface through melting of Sn metal powder as a binder is set within a range of 0 ?m<d?25 ?m. In order to attain the range, binder metal powder having a maximum particle diameter of 25 ?m or less is used.

Abstract: A gas turbine engine bearing assembly for a portion of a shaft that rotates around an axis, including a substantially cylindrical bearing having a length extending between a first end and a second end along the axis of the rotating shaft. A plurality of segmented damper springs are positioned around an exterior perimeter of a portion of the cylindrical bearing. Each spring has a width along the axis of the rotating shaft and a portion of each spring defines an outer spherically contoured joint. The width of each spring is less than the length of the bearing.

Abstract: The invention relates to a fluid dynamic bearing system having a stationary bearing component and a moving bearing component, that are separated from one another by a bearing gap filled with a bearing fluid. There are two radial bearing regions separated from one another and marked by radial bearing grooves. A separator region having a larger bearing gap width is disposed between the radial bearing regions. The radial bearing grooves of the two radial bearing regions have inner ends facing each other and outer ends facing away from each other. At least the outer ends of the radial bearing grooves are connected to each other by connecting grooves. According to the invention, wear zones provided especially for this purpose are disposed adjoining the connecting grooves, so as to prevent material wear at other regions of the bearing.

Abstract: A shaft member for hydrodynamic bearing apparatuses which can restore the pressure balance in a thrust bearing gap formed on both axial sides of the flange portion in an early stage is provided at low costs. A shaft material 10 integrally having a shaft portion 11 and a flange portion 12 is formed as a through-hole 19 opening to its both end faces 12a, 12b on the flange portion 12 of the shaft material 10 is formed in a common forging step. As a result, the through-hole 29 is formed to open to the inner diameter side of these bearing gap W1, W2 avoiding thrust bearing gaps W1, W2 formed on both end faces of the flange portion 22 of the shaft member 2 as a finished product.

Abstract: A system is provided that increases the spindle stiffness of a disk drive while optimizing power consumption. A multipurpose bearing provides axial stiffness and enhanced stiffness against radial and pitch loads applied to the spindle. When used in combination with a journal bearing, conventional thrust bearings may be eliminated without sacrificing overall stiffness. As a result, the height of the disk drive may be reduced, thereby making the system desirable to be used in smaller electronic devices.

Abstract: The present invention relates to an airfoil-magnetic hybrid bearing, which is a combination of a magnetic bearing and airfoil bearing. An airfoil-magnetic hybrid bearing of the present invention comprises: a housing around a rotating shaft of a rotation device; an airfoil bearing positioned between the housing and the rotating shaft for forming dynamic pressure to levitate the rotating shaft during rotation of the rotating shaft; a magnetic bearing including a plurality of cores positioned radially between inner surface of the housing and outer surface of the airfoil bearing, the cores being projected to the center of the rotating shaft, and coils wound to the cores to levitate the rotating shaft using a magnetic attractive force generated by a current application thereto; and a coupling segment for coupling the airfoil bearing to the magnetic bearing directly.

Abstract: To provide a fluid dynamic pressure bearing device that achieves high rigidity against moment without degradation in assembly precision and bearing performance, bearing sleeves are arranged in an axial direction and coaxiality of radial bearing surfaces formed on inner peripheral surfaces of the bearing sleeves is set to 3 ?m or less. This secures width precision between the radial bearing gaps to prevent a degradation in bearing performance and a failure such as wear etc. caused by contact between a shaft member and the bearing sleeves. Further, a first radial bearing surface and a second radial bearing surface are provided on at least one sleeve, and this allows a sleeve assembly constructed from the bearing sleeves to be supported at least three positions in the axial direction in a process of assembling the sleeve assembly.

Abstract: The invention relates to a bearing device (100) for the contactless bearing of a rotor in relation to a stator (101). Said bearing device (100) comprises a rotor provided with a shaft (102) and at least one rotor disk (103), and a stator (101) provided with at least two stator disks (105, 106). Said stator (101) at least partially surrounds the rotor at a certain distance and the rotor disks (103) protrude into the intermediate chamber (104) between the rotor disks thus forming a bearing gap (107). Said bearing device (100) also comprises a magnetic bearing part for bearing the rotor in a radial manner and an air bearing part for bearing the rotor in an axial manner.

Abstract: A fluid bearing structure with uniform depths of bearing concaves and a method of forming the bearing concaves in the fluid bearing structure. Pipe parts are inserted into through holes formed in the bearing base to form fluid spout holes for spouting fluid between confronting bearing surfaces. Bearing concaves are formed around the fluid spout holes. The bearing base and the pipe parts are made of different materials. A coating layer is formed on the bearing base and the pipe parts by an anodic oxidation process. Thickness of the coating layer on the bearing base is different from thickness of the coating layer on the pipe parts since the base member and the pipe members are made of different materials. The material on which a coating layer grows quickly is selected for the bearing base and the material on which a coating layer grows slowly is selected for the pipe parts.

Abstract: An object is to reduce manufacturing cost of a housing, and enable to disuse an adhesive in fixation portions between a housing and a bearing sleeve and the like. A housing 7 is made of resin material, which comprises a liquid crystal polymer (LCP) as crystalline resin blended with carbon nanotubes in a blending ratio of 2 to 35 vol % as a conductive filler, by injection molding. A bearing sleeve 8, which is inserted into the inner peripheral surface 7c of the housing 7, is secured to the housing 7 by ultrasonic welding.

Abstract: Cooling system for a hydrodynamic bearing bushing of annular appearance positioned in a support body, equipped with means of distributing cold oil under pressure to a shaft rotating in the bearing bushing, wherein it consists of a thin annular shell, the external surface of which is closely fitted into the bore of said support body, grooves being made in that part of said bore that corresponds to the angular region of the bearing bushing on which the load is applied during operation, said grooves being supplied with cold oil tapped downstream from the distribution means.

Abstract: A bearing apparatus for reducing vibrations in a compressor shaft (17) carrying a rotating compressor (10) is provided. The bearing apparatus comprises a first bearing (14) for supporting the shaft (17) and a second bearing (13) spaced outboard from the first bearing (14) for producing a moment on the shaft and additional damping counter to the direction of vibrations.

Abstract: A bearing device for a main shaft of a wind turbine includes a fixed hollow-cylindrical portion adapted for being mounted at a machine nacelle of the wind turbine. An inner diameter of the hollow-cylindrical portion is larger than the outer diameter of the main shaft such that a cavity is formed therebetween when the main shaft is inserted into the hollow-cylindrical portion. Furthermore a fitting provides a lubricating fluid to the cavity between the fixed hollow-cylindrical portion and the main shaft.

Abstract: Highly reliable hydrodynamic bearing device and spindle motor are provided as a result of improving cleanliness by using an iron metal having austenite structure, which is a non-magnetic body, and solving the problem of lowering of abrasion resistance due to low hardness. A shaft is formed using an iron metal having austenite structure, and a surface treated layer dispersed with solid lubricant is formed on at least a part of the surface of a shaft facing a sleeve by spraying fine particles of solid lubricant. Cleanliness is improved since the shaft is formed using an iron metal having austenite structure, which is a non-magnetic body. Further, since the surface treated layer dispersed with solid lubricant is arranged on the bearing surface, the abrasion resistance is enhanced and excellent bearing reliability is obtained.

Abstract: Disclosed is a fluid dynamic bearing device in which it is possible to prevent detachment of the shaft member reliably and at low cost without involving any increase in the device size. In a thrust bearing portion T, the lower end surface of the shaft member is held in contact with a thrust plate, and the shaft member is rotatably supported in the thrust direction. Protrusions extending radially inwards are provided on a sealing portion attached to an opening of the housing, and these protrusions are engaged with a small diameter portion formed on the outer peripheral surface of the shaft member, thereby preventing the shaft member from coming off.

Abstract: An inertial navigation system is provided. The system includes a sensor block, an outer shell that substantially surrounds the sensor block and a plurality of gas pads connected to the outer shell that float the sensor block in gas creating a near frictionless environment to allow the sensor block to rotate in all directions. Each of the plurality of gas pads is adapted to receive pressurized gas. The outer shell and the sensor block are separated by a gap created by the pressurized gas at each pad.

Abstract: An air bearing has a rotor having a circularly curved radial rotor bearing surface along its circumferential direction. The air bearing also has a stator having at least one radial stator bearing surface partially enclosing the rotor in the circumferential direction. The radial stator bearing surface is curved according to a profile following the circumferential direction of the rotor and is fashioned to generate an air gap between it and the radial rotor bearing surface so that, upon operation, the rotor is borne, supported by an air current in the air gap. The profile shapes the air gap such that, at a starting temperature that deviates from an operating temperature, the air gap has a smaller thickness (measured in the radial direction) in a second region of the radial stator bearing surface in comparison to a first region of the radial stator bearing surface along the circumferential direction.

Abstract: The hydrodynamic bearing device has a sleeve composed of a sintered material and having a compression-absorbing space inside the sleeve, the sleeve having a bearing hole in the center thereof; a shaft rotatably inserted into the bearing hole; a bearing portion formed between the bearing hole and the shaft; a hydrodynamic groove formed on at least one of the internal peripheral surface of the bearing hole and the external peripheral surface of the shaft; a concavity having one or more steps and formed to one end of the sleeve in the axial direction; a convexity formed to the other end of the sleeve in the axial direction, the convexity having a shape similar to the concavity; and a lubricating fluid filled in the gap of the bearing portion. The hydrodynamic bearing device has a readily obtainable predetermined shape precision, the internal density of the sintered material is made uniform, and lubricating fluid therein does not leak from the surface.

Abstract: Peeling-off of an oil-repellent film can be reliably prevented. A fluid dynamic bearing device (1) includes a shaft member (2) and first and second flange portions (9, 10) serving as seal portions fixed to the shaft member (2). On outer peripheral sides of the first and second flange portions (9, 10), a first seal space (S1) and a second seal space (S2) are formed, respectively. Oil-repellent films (11) are provided on end surfaces of the first flange portion (9) and the second flange portion (10) separately from a pressure-receiving surface (12) subjected to pressure at a time of assembly, the end surfaces being exposed to external air.

Abstract: Provided is a fluid bearing device in which run-out of another member fixed to a shaft member is suppressed. At one end of a shaft member (2), there is provided a press-fitting fixation surface (2a4) to which a hub (3) can be press-fitted and fixed. Further, between the press-fitting fixation surface (2a4) and an end surface (2d), there is provided a guide portion (10) to be used when press-fitting the hub (3) onto the press-fitting fixation surface (2a4). The guide portion (10) is provided with a cylindrical surface (11) of a smaller diameter than an inner peripheral surface (3b) of the hub (3).

Abstract: A hydrodynamic bearing device 4 comprises a shaft 41, a second thrust flange 41c, a sleeve 42, a radial bearing 71, and a thrust bearing 73. The second thrust flange 41c is fixed near one end of the shaft 41. A third cylindrical protrusion 42e that protrudes farther in the axial direction than the second thrust flange is fixed to or integrally machined at one end of the sleeve 42. A notch 50 that communicates between a radial inner space and a radial outer space separated by the third cylindrical protrusion 42e is provided to the third cylindrical protrusion 42e.

Abstract: A plain bearing with a bearing body in which a body, which is to be stored is arranged, is disclosed. The bearing body is surrounded by a supporting body. The bearing capacity is improved by virtue of the fact that the bearing body has a partial joint arranged at an angle in relation to the horizontal. The plain bearing has an active cooling system and an articulated lubrication system.

Abstract: An aerostatic device for ultra precision machine tools, the aerostatic device having a damping device for use at any angle, including vertical, and comprising a male part (14) having a projecting portion (16), a female part (10) having a channel (12) in which the projecting portion (16) of the male part (14) is slidably receivable, means (22) for providing a magnetic field, the magnetic field means being at or adjacent to the projecting portion (16) of the male part (14) and/or the channel (12) of the female part (10), and magnetic oil (26) interposed between the projecting portion (16) of the male part (14) and the channel (12) of the female part (10) and only within the magnetic field of the magnetic field means. The in use magnetic oil (26) being retained in or substantially in position by the magnetic field, so that undesirable movement of the male part (14) and/or female part (10) is damped by the oil (26) without the oil (26) being displaced from the projecting portion (16) and/or the channel (12).

Abstract: [Problems] Provided is a fluid bearing device in which bearing sleeves are positioned and fixed with respect to a housing with high accuracy. [Solving Means] To an inner periphery of a housing (7), a first bearing sleeve (8) and a second bearing sleeve (9) are fixed while being spaced apart in an axial direction. Between the bearing sleeves (8) and (9), a spacer (10) made of a resin is disposed. An axial rigidity of the spacer (10) is smaller than those of the first bearing sleeve (8) and the second bearing sleeve (9). Accordingly, in a state where the first bearing sleeve (8) and the second bearing sleeve (9) are positioned and fixed with respect to the housing (7), the spacer (10) is largely compressed in an axial direction compared to the bearing sleeves (8) and (9).

Abstract: A fluid dynamic bearing includes a bearing member (30) axially defining an inner bearing hole therein, and a spindle shaft (20) rotatably received in the bearing hole with a bearing clearance formed between an inner periphery of the bearing member and an outer periphery of the spindle shaft. Lubricant is filled in the bearing clearance. One of the inner periphery and the outer periphery comprises a bearing surface (10) with channels formed therein. The channels form a plurality of outer communication ends (1316b) at opposite sides of the bearing surface in the axial direction of the bearing member.

Abstract: Provided is a fluid bearing device with a hub part having high molding precision and dimensional stability and capable of being produced at low cost. An annular gate (14) is formed at a portion of a cavity (15) corresponding to an outer peripheral edge portion of a lower end surface (10c1) of a flange part (10c), and a molten resin (P) is filled into the cavity (15) through the annular gate (14) to form a hub part (10) made of resin. The hub part (10) molded by the injection molding exhibits a radial resin orientation through an entire periphery thereof. Further, an annular gate trace (16) is formed at the outer peripheral edge portion of the lower end surface (10c1) of the flange part (10c) of the hub part (10).