Abstract: The porous oil-impregnated bearing 1 comprises a bearing body 1a made of a porous material, and oil retained in the pores of the bearing body 1a by impregnation with lubricating oil or lubricating grease. The inner peripheral surface of the bearing body 1a is formed with a bearing surface 1b opposed to an outer peripheral surface of a shaft to be supported, with a bearing clearance defined therebetween. The bearing surface 1b has a first region m1 in which a plurality of hydrodynamic pressure generating grooves 1c inclined in one direction with respect to the axial direction are circumferentially disposed, a second region m2 which is axially spaced from said first region m1 and in which a plurality of hydrodynamic pressure generating grooves 1c inclined in the other direction with respect to the axial direction are circumferentially disposed, and an annular smooth region n disposed between teh first and second regions m1 and m2.

Abstract: The porous oil-impregnated bearing 1 comprises a bearing body 1a made of a porous material, and oil retained in the pores of the bearing body 1a by impregnation with lubricating oil or lubricating grease. The inner peripheral surface of the bearing body 1a is formed with a bearing surface 1b opposed to an outer peripheral surface of a shaft to be supported, with a bearing clearance defined therebetween. The bearing surface 1b has a first region m1 in which a plurality of hydrodynamic pressure generating grooves 1c inclined in one direction with respect to the axial direction are circumferentially disposed, a second region m2 which is axially spaced from said first region m1 and in which a plurality of hydrodynamic pressure generating grooves 1c inclined in the other direction with respect to the axial direction are circumferentially disposed, and an annular smooth region n disposed between the first and second regions m1 and m2.

Abstract: A bearing mechanism eliminates the need for lubricating oil, is capable of generating enough radial dynamic pressure even in lower-speed regions, and yet can be easily surface-machined for the generation of radial dynamic pressure and manufactured with low cost. In at least either one of an outer circumferential surface 2a of a first member 2 or an inner circumferential surface 3a of a second member 3 (hereinafter, referred to as roughened surface), the two circumferential surfaces being opposed to each other with a bearing gap G therebetween, dot-like minute dips and bumps are formed dispersedly, by which the surface is roughened so that its center-line mean roughness is controlled within a range of 0.1 &mgr;m-1.0 &mgr;m.

Abstract: An annular fluid film bearing is formed of a stator ring and a rotatable element concentrically mounted within the stator ring such that an annular clearance is defined between the inner surface of the stator ring and the outer surface of the rotatable element. Fluid flows through the annular clearance, and hydrostatic pressure of the fluid in the clearance provides radial support to the rotatable element and stiffness and damping for the bearing. A diffuser and inlet flow guide is mounted adjacent the inlet end of the annular bearing clearance. The diffuser and inlet flow guide comprises a ring having a plurality of flow passages formed in its inner surface facing the rotatable element. The flow passages are configured to turn the fluid approaching the inlet of the annular bearing clearance such that the fluid entering the annular clearance has a tangential velocity opposite to the direction of rotation of the rotatable element.

Abstract: A hydrostatic bearing assembly, with an integral rotating-shaft hydrodynamic pump, adapted for use as a stiff zero static-friction actuator pivot bearing for the head-stack assembly of a disk drive data storage apparatus. The zero static-friction pivot bearing avoids all “limit cycling” and “sticking” problems arising from static bearing friction during micro-tracking operations. The motor-driven hydrodynamic pumping element is disposed coaxially to the zero static-friction hydrostatic bearing element in a single assembly adapted for use as an actuator pivot bearing. The hydrodynamic pumping element and the hydrostatic bearing element both use a plurality of spaced-apart radial journal-bearing layers and a plurality of axial thrust-bearing layers to provide stiffness in all directions at any rotational velocity.

Abstract: The invention relates to a rotary screw machine that is completely oil-free. Known rotary screw machines with cooling, sealing, lubrication of the screw rotors and oil-lubrication and oil-cooling of the bearings have been replaced with water-lubricated and water-cooled bearings. Each screw rotor (102) is mounted in a water-lubricated radial slide bearing (1) and one trunnion (31) of the rotor co-acts with a water-lubricated thrust bearing (9, 10) which acts both as an hydrodynamic and an hydrostatic bearing. The trunnion bearing housing (21) is in fluid connection with the rotor housing, both along the trunnion and via a conduit (27) from the bearing housing interior to the gas inlet (108) of the screw rotor or via a channel which is cut-off from said inlet.

Abstract: The porous oil-impregnated bearing 1 comprises a bearing body 1a made of a porous material, and oil retained in the pores of the bearing body 1a by impregnation with lubricating oil or lubricating grease. The inner peripheral surface of the bearing body 1a is formed with a bearing surface 1b opposed to an outer peripheral surface of a shaft to be supported, with a bearing clearance defined therebetween. The bearing surface 1b has a first region m1 in which a plurality of hydrodynamic pressure generating grooves 1c inclined in one direction with respect to the axial direction are circumferentially disposed, a second region m2 which is axially spaced from said first region m1 and in which a plurality of hydrodynamic pressure generating grooves 1c inclined in the other direction with respect to the axial direction are circumferentially disposed, and an annular smooth region n disposed between the first and second regions m1 and m2.

Abstract: The dynamic pressure bearing device is structured such that the pores of porous material as they are are disposed in the surfaces thereof forming the negative pressure cancel portions 15b and a lubricating fluid is supplied to the negative pressure generating areas thereof through the pores of the negative pressure cancel portions 15b, whereby, even if recess-shaped grooves forming the negative pressure cancel portions 15b are formed shallow in depth and wide in width, or even if such grooves themselves are not formed at all, the dynamic pressure bearing device is able to fulfill its negative pressure cancel function in a sufficient manner. This makes it possible to eliminate the need for provision of the conventional recess-shaped grooves which are formed deep and narrow, thereby eliminating the need to execute an expensive operation such as a cutting operation or the like, so that the negative pressure cancel portions 15b can be formed at a low cost by inexpensive means such as by molding or the like.

Abstract: A bearing for supporting a rotating shaft receiving a transverse load, wherein the bearing supports the shaft along a load line and wherein the bearing is closest to the rotating shaft at a running line. The bearing includes a circumferential inner surface, and a lubricant bay defined in the inner surface. The lubricant bay is axially and circumferentially offset from the load line such that a resulting pressure pad of lubricant within the bay provides a hydrostatic force that forces the running line to a location substantially perpendicular to the load line. Load capabilities of a bearing according to the present disclosure, therefore, are substantially insensitive to shaft bending and do not deteriorate in response to the shaft bending.

Abstract: In a motor having a bearing housing 7 with a hollow portion 23, a radial bearing 9 held in the hollow portion 23, a thrust receiving plate 8 provided at one end of the hollow portion 23, and a rotary shaft 1 which is rotatably supported by the radial bearing 9 in a state that an extreme end thereof is in contact with the thrust receiving plate 8, the bearing housing 7, shaped like a cup, includes a cylindrical portion 21 and a bottom portion 22 defining one end of the cylindrical portion 21, the cylindrical portion 21 and the bottom portion 22 define the hollow portion 23, the radial bearing 9 is firmly held with the inner surface of the cylindrical portion 21, and the thrust receiving plate 8 is supported on the bottom portion 22.

Abstract: It is an object of the invention to provide a bearing device in which the bearing performance is not lowered even when the temperature is changed. In order to attain the object, the bearing device has a shaft and a sleeve. The shaft is made of stainless alloyed steel and has dynamic pressure generating grooves of a herringbone-like shape. The sleeve consists of the body made of a copper alloy, and an electroless nickel plated layer which covers the whole surface of the body. The electroless nickel plated layer has a coefficient of thermal expansion which is smaller than that of the body made of a copper alloy. The coefficient of thermal expansion of the shaft made of stainless alloyed steel is smaller than that of the body of the sleeve made of a copper alloy. When the temperature is raised, the electroless nickel plated layer suppresses the amount of thermal expansion of the body.

Abstract: The invention relates to a dynamic groove bearing (9) comprising an internal bearing part (23) and an external bearing part (17) which are rotatable relatively to each other about an axis of rotation (7), a bearing surface (31, 35) of one of the bearing parts comprising two grooves for co-operation with a bearing surface (39) of the other bearing part. The groove bearing further comprises a reservoir made from a porous material for a lubricant which is present between the bearing surfaces. According to the invention, the reservoir is mounted between the two groove patterns, viewed in a direction parallel to the axis of rotation. In this manner, a uniform supply of the lubricant from the reservoir to the two groove patterns is obtained, while also the number of parts of the groove bearing is limited. In a preferred embodiment, the reservoir comprises a ring-shaped body (29) which is made from the porous material and mounted in the external bearing part.

Abstract: A plurality of hydrostatic bearing pads are each integrally formed in a respective pin or journal member being used within a mechanical press machine. The hydrostatic bearing pads are supplied with pressurized fluid sufficient to create a combined hydrostatic and hydrodynamic effect between the opposed bearing surfaces of the pin and an associated bushing. The hydrostatic bearing pads are used in conjunction with rotational and oscillating bearings in which relatively little rotation, oscillation, or slow rotational speeds exist or where it is desired to minimize the effects of hydrodynamic action which creates bearing “lift off” on journal bearings. These types of bearings are particularly associated with crankshaft and connection journal bearings, connection pins, and pivot pins used by a rocker-type coupling assembly that couples a weight assembly to the press machine piston or slide assembly or drive assembly.

Abstract: A self-acting air bearing wherein an abrasion-generated substance is generated by rotation of a shaft and a bearing and is used as a lubricant. As a result, a motor of low cost and stable rotation in which it is not necessary to insert special lubricant into the shaft or the bearing previously can be achieved. Moreover, in a polygon motor having such a lubrication structure, since polluting of a writing system is not feared, reliability for a long time period can be obtained.

Abstract: Provided is a hydrodynamic gas bearing structure which can prevent occurrence of whirl not only in high-speed rotation but also in low-speed rotation, reduces such frequency that a floating rotational frequency in starting or stoppage of rotation increases, and is capable of shifting the floating rotational frequency to a low rotational frequency side. The hydrodynamic gas bearing structure comprises a shaft body (1) and a bearing body (2). A groove (11) is formed on the outer peripheral surface of the shaft body (1). The groove (11) consists of at least two concave parts, whose depths substantially differ from each other, which are formed serially in the circumferential direction, and has a circumferentially asymmetrical shape in a cross section perpendicular to the axis.

Abstract: An orifice compensated hydrostatic bearings wherein a roughened surface area retards the hydrostatic fluid flow exiting the hydrostatic bearing reducing the whirl frequency ratio while increasing the bearing stiffness and life.

Abstract: A hydrostatic bearing is uniquely configured for improved operability. A hydrostatic bearing (32) has a collar (42) that circumscribes a shaft (18) to define a fluid film annulus (50) for radially confining a load supportive fluid film. An array of pockets (52) distributed circumferentially along a bearing surface (48) communicate with vent regions (64a, 64b) in which the vent pressures are substantially unequal. Supply passages (76) associated with the pockets (52) are oriented at an angle .theta. for injecting fluid into the annulus with an axial directional component directed toward the higher pressure vent region. The orientation angle .theta. compensates for the propensity of the fluid to preferentially feed the low pressure side of the bearing. Further, a hydrostatic bearing (132) has a collar (142) that circumscribes a shaft (118) to define a fluid film annulus (150) for radially confining a load supportive fluid film.

Abstract: An air bearing comprising a static shaft having a circumferential surface in a form which when developed into a substantially flat plane takes the form of a series of shallow sinusoidal waves having at least three wave peaks, wherein one of the peaks carries a groove extending longitudinally parallel to the shaft axis and which bearing further comprises a hollow support member mounted for rotation around the static shaft.

Abstract: The parameters of a rotor bearing assembly are readily changed to facilit evaluation, determination and establishment of optimum bearing clearance and rotor bearing adjustment to minimize noise and vibration, by an arrangement which includes seating of solid deflection pads positioned within a carrier on replaceable adjustment shims and retention of the pads and shims seated in adjusted positions by means of hold-down screws.

Abstract: The invention provides a dynamic pressure bearing capable of generating enough dynamic pressure even with the use of a porous material. Dynamic pressure grooves at an inner circumferential surface of a sleeve made of porous material are formed by rolling process. Voids of the porous material at a surface of the dynamic pressure grooves are crushed by this rolling process, making the dynamic pressure grooves airtight. Further, the inner circumferential surface at which the dynamic pressure grooves are formed is subject to a sizing process, by which a bearing surface of the sleeve is crushed so that substantially no voids are present.

Abstract: Herringbone grooves are formed on an inner wall of a sleeve through which a motor shaft is inserted. Lubricating fluid is provided between a space between the shaft and the sleeve so as to form a relatively rotatable radial dynamic pressure bearing. A surface layer and the herringbone grooves on an inner wall of the sleeve, which are sliding regions with the motor shaft, have a different hardness from that of a base material of the sleeve. The hardness ratio of these two elements is set so that the shaft spins without wearing itself out as well as the sleeve surface layer. As a result, a highly reliable motor is achieved because the structure can maintain accurate whirling and suppress seizure due to abrasion powder between the shaft and the sleeve.

Abstract: A brushless DC motor is disclosed. In the motor, an axial vibration limit unit is provided on a bearing and electromagnetically attracts a rotor, thus preventing the rotor from being centrifugally lifted during a high speed rotation of the rotor. In the operation of the motor, an axial displacement of the rotor is sensed by an induction coil of a sensor. The induction coil generates a variable induction current indicative of an axial displacement of the rotor, and outputs the current to a controller through an amplifier, thus controlling the vibration limit unit. The electromagnetic bearing of this invention thus supports the shaft and rotor in an axial direction and almost completely prevents any axial vibrations of the rotor, thereby reducing operational vibrations and noises and improving the axial dynamic characteristics of the brushless DC motor.

Abstract: A journal bearing apparatus capable of varying the clearance between a bush which protrudes from the inner surface of a sleeve in which a rotation shaft is inserted and the outer surface of the rotation shaft, in the longitudinal direction of a first dynamic pressure generating groove. Moreover, a journal bearing apparatus is capable of varying the clearance between one end of the rotation shaft and the surface of a thrust bearing, in the diametral direction of a second dynamic pressure generating groove. The clearance becomes wider towards the central part from the ends of the bush, or towards the central part from the edge parts of the surface of the thrust bearing. The shape of the end of the bush or the thrust bearing is preferably a circular arc. Thereby, the fluid pressure on the rotation shaft which faces the first and second dynamic pressure generating grooves is uniform.

Abstract: A bearing assembly comprises a piston mounted within and capable of reciprocating with respect to a fixed bearing shell. The bearing shell is provided with openings for the supply of a bearing medium, such as compressed air, into a clearance between the piston and the bearing shell. The bearing shell is tapered circumferentially which renders the bearing shell flexible. As the diameter of the piston increases due to thermal expansion, the diameter of the bearing shell changes automatically to maintain the clearance therebetween.

Abstract: A rotating shaft motor or cartridge incorporates an o-ring which surrounds the rotating shaft and is borne on a carrier. As supported on the carrier, the o-ring does not normally block the bearing passages which would prevent the smooth distribution of oil throughout the motor. However, the carrier and o-ring combination are designed to allow the o-ring to be forced into an opening between the shaft and sleeve for completely sealing the remaining portion of the bearing during filling. The rotating shaft includes a central reservoir, having one or more grooves or passages communicating with the hydrodynamic bearing surfaces and ending in a septum or rubber plug which is inserted in an opening in the shaft.

Abstract: A sleeve bearing structure for holding a shaft rotating in a first direction includes a bearing having an inward wall defining therein a through hole, a bearing stand engaged with the bearing for supporting the bearing and having a cavity which is in communication with the through hole at the bottom thereof below the bearing, and a first set of threads formed in the first direction on a first part of the inward wall.

Abstract: A hydrodynamic bearing apparatus and a method for manufacturing a hydrodynamic bearing apparatus consists of providing a shaft and rotatably fitting the shaft to a bearing. Hydrodynamic pressure generating grooves are cut on the bearing surface of either the bearing or the shaft. The bearing surface that has the hydrodynamic pressure generating grooves thereon faces another bearing surface so that the bearing and shaft rotate with respect to one another, and the bearing or the shaft that has a bearing surface having the hydrodynamic pressure generating grooves is comprised of a thick main body member and a thin sleeve fitted to the main body member. The thin sleeve is thinner and made of a softer material than the main body member, the thin sleeve is evenly deformed, and the hydrodynamic pressure generating grooves are cut on a surface of the thin sleeve.

Abstract: A rotary polygon mirror optical scanning device comprises a fixed shaft and a rotor having a shaft hole, to which the fixed shaft is inserted, and is rotatably supported against an outer perimeter of the fixed shaft. The device also includes a hydrodynamic bearing mechanism for supporting the rotor. The hydrodynamic bearing mechanism has first and second hydrodynamic pressure generating grooves which are, axially away from one another, formed on at least one of an outer surface of the fixed shaft and an inner surface of the shaft hole of the rotor. A rotary mirror is mounted on the rotor. A motor portion is arranged for rotating the rotor. The fixed shaft has a diameter bearing which is one-third or more of a diameter of a polygonal inscribed circle of the rotary polygon mirror. An area for cutting the first hydrodynamic pressure generating groove is arranged at an axially identical position with the rotary polygon mirror.

Abstract: A bearing having two surfaces (60, 72) rotatable with respect to each other, a lubrication medium located in a gap between the tow surfaces during rotation of the bearing and a sinusoidal groove pattern (20) formed on one of the tow surfaces to distribute the lubrication medium over the surface of the bearing and create a pressure distribution in the bearing to create a stiff hydrodynamic bearing.

Abstract: The invention is a spindle motor including a rotor hub bearing a rotational load, lubricant-containing bearing systems rotatably supported by the rotor hub, and stator windings wound on a stationary member, so as to oppose the rotor magnet. At least a portion of the rotor hub is in a clean environment, with the motor substantially sealed by a sealing unit. The spindle motor has a leakage prevention unit which prevents the lubricant trying to leak out the bearing systems and out the motor, when centrifugal forces produced by a rotor hub rotating at a high speed are exerted on the lubricant.

Abstract: A bearing system for brushless DC motors is disclosed. The bearing system has an electromagnetic force generator in a bearing so as to generate an electromagnetic force or a magnetic force. The bearing system thus magnetically attracts the shaft when eccentricity of the shaft in the bearing is reduced during a high speed operation of the shaft, thus allowing the shaft to keep desired eccentricity in the bearing and increasing dynamic pressure of oil in the bearing and preventing a formation of an oil whirl, and improving dynamic characteristics of the motor such as low operational vibrations and noises during a high speed operation of the motor.

Abstract: This invention relates to vertical bearing assemblies employed to support vertically extending rotatable shafts and provide thrust and/or journal bearing support therefor, and in particular relates to lubricant arrangements therefor.

Abstract: To achieve an efficacy of allowing a shaft to spin in high speed without contacting the bearing in which the shaft is seated, a bearing is configured to comprise an inner ring which includes: at least two slant arc surface zones each spaced out from the surface of the shaft with a gap shrinking, in the spinning direction of the shaft, to a thickness approximately equal to a preset minimum value.

Abstract: It is an object of the invention to provide an inexpensive and high-quality fluid bearing which improves the workability in assembly or coupling of a shaft and a rotator. In order to achieve this object, a fluid bearing according to the invention includes a rotating shaft, a bearing member for rotatably supporting the rotating shaft, and first and second fluid film formation mechanisms arranged at positions near a central portion of the rotating shaft along its longitudinal direction. The first fluid film formation mechanism forms a fluid film between the rotating shaft and the bearing member while the rotating shaft rotates in a first direction. The second fluid film formation mechanism forms a fluid film between the rotating shaft and the bearing member while the rotating shaft rotates in a second direction opposite to the first direction.

Abstract: A magnetic fluid bearing unit has a bearing housing, a bearing member having magnetic fluid as a lubricating agent, a rotary body rotatively supported by the bearing member, an upper permanent magnet arranged inside the bearing housing, and a lower permanent magnet arranged inside the bearing housing, the bearing member being sandwiched by the upper permanent magnet and the lower permanent magnet. The bearing member is a radial porous oil-containing bearing member in which the magnetic fluid is impregnated. The upper permanent magnet is set to have one direction of magnetic pole orientation, and the lower permanent magnet is set to have the same direction of magnetic pole orientation as the upper permanent magnet. The bearing member is sandwiched by the upper permanent magnet and the lower permanent magnet to confine the magnetic fluid. Over a wide range of rotation speeds, the leakage and the scattering of the magnetic fluid from the bearing unit can be prevented.

Abstract: A mechanical assembly of shaft and static pressure bearing including a static pressure bearing mechanism formed in a shaft. The bearing mechanism includes an air supply chamber, a plurality of air conduits, a plurality of porous bodies each secured in a respective one of the plurality of air conduits, a glass layer applied on outer surfaces of the porous bodies as well as on an end face of the shaft, a plurality of pockets formed in the glass layer at positions corresponding to the air conduits, and a plurality of orifices formed in each of the plurality of pockets such that a gap formed between the glass layer and a bearing main body is communicated with the air supply chamber by the pockets, orifices and porous bodies. The pockets and orifices can be formed simultaneously by a laser machining. A distribution in pressure within a gap formed between the glass layer and a bearing main body can be uniform.

Abstract: A spindle for a gas bearing of a rapidly rotating tool, including a spindle housing, a bushing arranged in the housing, at least one ceramic bearing pressed into the bushing over substantially the entire length thereof and a rotating shaft gas-supported in the housing in the axial and radial direction by the bearings such that a gap remains between the shaft and the bearings. In order to control the narrowing of the gap formed between the shaft and the bearings, the material and thickness of the bushing and bearing are selected such that the product of elasticity module and wall thickness of the bushing is at least about 1.8 times greater than the product elasticity module and wall thickness of the bearing.

Abstract: A rotary drum assembly is arranged so that upper and lower drums can rotate about a central shaft with respect to each other via a dynamic-pressure bearing. In the rotary drum assembly, the central shaft is press-fitted into the rotary upper drum, a sleeve which is formed so that the central shaft can be rotatably fitted thereinto is supported by the fixed lower drum, and a dynamic-pressure generating groove is formed in either one of the central shaft and the sleeve, whereby a dynamic-pressure bearing is formed between the central shaft and the sleeve.

Abstract: A bearing for supporting rotating equipment, a fluid handling system associated therewith, a control system therefore, method and apparatus is disclosed in which a rotating shaft is suspended in a fluid. Shaft precession is monitored to provide a compensatory feed back loop to maintain proper shaft registry in the face of loads.

Abstract: A spindle motor having hydrodynamic bearings formed between a hardcoated shaft with a radial thrust bearing plate substantially perpendicular to the axis of the shaft, a hard coated sleeve, and a hardcoated thrust ring. An axial bearing cavity is formed between the sleeve and the shaft. A first radial bearing cavity is formed between a radial surface of the sleeve and a lower radial plate surface. A second radial bearing cavity is formed between a lower surface of the thrust ring and an upper radial plate surface. Lubricant at least partially fills the cavities to form hydrodynamic bearings therein. The surface hard coats are preferably ceramic-like coatings such as titanium nitride, boron carbide, or Laser Cut 964. A method for fabricating a motor having hydrodynamic bearings includes the steps of machining motor components from a metal such as steel or bronze, coating the components with a surface hard coat, and assembling the motor.

Abstract: A method for forming a precision groove in a cylindrical surface of an article such as a sleeve-shaft hydrodynamic journal bearing system includes the steps of: aligning a groove-forming machine to an axial datum plane of the article defined in a spaced-apart relation with the cylindrical surface by a predetermined nominal first dimension, translating the groove-forming machine in an axial direction toward and upon a first edge of the cylindrical surface by an amount equal to the predetermined nominal first dimension and thereupon forming a first groove axial step segment in the cylindrical surface until a second predetermined axial datum plane is reached, simultaneously axially translating and rotating the groove-forming machine from the second axial datum plane until a third predetermined axial datum plane is reached and thereupon forming the precision groove pattern in the cylindrical surface between the second axial datum plane and the third axial datum plane, and axially translating the groove-forming ma

Abstract: A self pressurizing journal bearing assembly includes a tubular housing having a bore defining a plain cylindrical journal bearing, and a cylindrical rotary shaft disposed coaxially therein. The shaft includes a plain cylindrical journal spaced radially inwardly of the bearing to define a journal bearing gap. A screw pump is defined in part by a portion of the shaft, and is disposed inside the housing bore in flow communication with the journal bearing for continually circulating a lubricant thereto under pressure upon rotation of the shaft for accommodating lubricant end leakage from the journal bearing.

Abstract: A helically continuous projection 1a is formed around a sliding surface 1A of a sliding bearing 1 at a given pitch p. The surface roughness h of the sliding surface 1A, including the projection 1a, is chosen to be equal to or less than one-half the height H of the projection. This provides a sliding bearing 1 which exhibits an improved running-in performance.

Abstract: A bearing device includes a housing, a shaft arranged in an inner circumference of the housing, and a pair of bearings arranged between the shaft and the housing, and spaced from each other in an axial direction of the shaft, at least one of the bearings comprising a sleeve inserted in the housing and formed cylindrically. The sleeve has an outer layer portion including an outer cylindrical surface and an inner layer portion including an inner cylindrical surface, the outer layer portion being harder than the inner layer portion, the inner cylindrical surface having a groove for generating dynamic pressure. The sleeve is improved in working accuracy, and the dynamic pressure generating grooves can be formed with ease.

Abstract: A hydrodynamically lubricated assembly is disclosed for adjustably and rotatably supporting the journals of work roll pairs in the housing of a roll stand in a rolling mill. The assembly includes a pair of eccentric sleeves journalled for rotation in the housing. Inner sleeves containing journal bearings are rotatably received in the eccentric sleeves, and the work roll journals are rotatably received in the journal bearings. Hydrodynamic and optionally also hydrostatic fluid supply networks communicate with the journal/bearing interfaces via radial conduits in the inner sleeves and journal bearings. The inner sleeves are anchored against rotation, and the eccentric sleeves are rotatable to adjust the parting between the work rolls.

Abstract: A fluid dynamic bearing is described having an inner element made of a first material with a first coefficient of thermal expansion, an outer element made of a second material with a second coefficient, and a layer of viscous fluid in contact with and separating the inner element from the outer element such that said outer element is capable of rotation around said inner element. By choosing particular materials, the difference between the first and second coefficients of thermal expansion can be controlled, and the thickness of the layer of viscous fluid can be made to vary with temperature. This allows for some degree of control over the temperature dependence of the stiffness and drag of the fluid dynamic bearing. In particular, the coefficients of thermal expansion can be chosen so as to cancel out any temperature dependence of stiffness and/or drag due to a temperature dependence of the viscosity of the viscous fluid.

Abstract: A memory disk driving apparatus has a dynamic pressure fluid bearing type spindle motor 1, wherein herringbone grooves 12a are formed on the shaft 12. In the dynamic pressure fluid bearing relatively rotatable with the intermediary of the lubricant injected into a gap between the shaft 12 and the sleeve 13; the shaft diameter D is selected 4 mm or less, and the ratio of the radial gap R between the shaft and the sleeve to the diameter D of the shaft (R/D) is between 0.0005 and 0.002.

Abstract: Provided is a dynamic pressure gas bearing structure which is applicable to a high-speed rotation driving part such as a hard disk driver or the like and has high rotational accuracy in high-speed rotation. The dynamic pressure gas bearing structure comprises a shaft body and a bearing body. When the shaft body and the bearing body are so arranged that central axes thereof are aligned with each other, a substantially cylindrical gap is defined between the outer peripheral surface of the shaft body and the inner peripheral surface of the bearing body. The gap has at least one gap change portion whose thickness is changed with respect to a central angle corresponding to the circumference along the outer peripheral surface of the shaft body. The gap change rate .alpha. is at least 1.0.times.10.sup.-4 /.degree. and less than 10.0.times.10.sup.-4 /.degree. .

Abstract: A hydrodynamic bearing (16) for a cutter cone assembly (12) that rotates around a journal (14). The bearing (16) comprises a plurality of grooves (88) on an outer surface (90) to produce undulations (82) on an inner surface (84) upon insertion of the bearing (16) into a bearing recess (94). Undulations (82) act as pockets to collect lubricant which is forced upon rotation of the bearing (16) between the outer journal surface (86) and the inner bearing surface (84) to produce a hydrodynamic film.

Abstract: A hydrodynamic bearing assembly including a shaft and surrounding bushing which define a journal, the shaft and bushing defining at the end thereof which is open to the ambient atmosphere a shelf-like surface. An absorbent washer, preferably formed of a very clean, particle free absorbent paper is placed on this surface, and preferably held in place by a plastic or metal retainer. Typically, the retainer is pressed in place and held in place by spring force or the like, so that the washer is held tightly against the surface.