Abstract: A fluid dynamic bearing having a shaft (12) and a bearing sleeve (11) rotatably supported relative to each other. At least one of the shaft and the bearing sleeve is made of steel or stainless steel made of by weight C: 0.6˜1.20%; Si: 1.0% or less; Mn: 1.0% or less; Cr: 10.5˜18.0%; Mo: 1.0% or less; S.: 0.03% or less; and Fe. The dynamic pressure bearing surface (20) is formed by ridges (22) remaining in between multiple dynamic pressure grooves (21) formed by electrochemical machining.

Abstract: A fluid dynamic pressure bearing device includes a shaft member (5) and a bearing member (41), at least one of the shaft member or the bearing member being rotatable with respect to the other. A shaft member-side annular member (13) is fixed with respect to the shaft member. The shaft member-side annular member includes a large-diameter rim portion and a small-diameter outer circumferential surface portion. A bearing member-side annular member (14) is fixed with respect to the bearing member. The bearing member-side annular member includes an inner circumferential large-diameter step portion, and a small-diameter inner circumferential surface portion.

Abstract: A fluid dynamic bearing mechanism for a motor (1) suitable for use in a hard disk drive and having a compact and thin shape, high bearing rigidity, and high rotating accuracy, and which securely keeps the rotor member (6) in place against shocks, and allows the inspection of lubricant supply amount easily. A fluid dynamic bearing mechanism having a capillary seal part (12) on one end of lubricant supply part formed by a minute gap including dynamic pressure grooves (10) formed on a shaft member (5) or a bearing member (4) is provided. An annular member (13) is fitted on the shaft member at the location corresponding to the capillary seal part, another annular member (14) is fitted on the bearing member at the location corresponding to the capillary seal part, a taper or step (13a, 14a) is formed on the outer peripheral surface of the annular member on the shaft member side and the inner peripheral surface of the annular member on the bearing member side.

Abstract: A fluid dynamic bearing is provided. A structure in which a shaft member and an annular member fitted about the shaft member are rotatably supported by a bearing member and an annular member on the bearing member has a fifth gap for storing a lubricating fluid and supplying it to a second gap below the annular member on the shaft member and a third gap around its outer periphery through a fourth gap. The fourth and fifth gaps are tapered to produce a capillary drawing force toward the third and second gaps, so that the lubricating fluid may be supplied effectively from the fifth gap to the second and third gaps. This makes it possible to suppress any sudden formation of a reduced pressure upon exposure to impact or vibration to prevent the leakage of any lubricating fluid caused by the generation of bubbles, while making up for the loss of any lubricating fluid by vaporization.

Abstract: A fluid dynamic bearing (1) with a rotating shaft (3) inserted into a sleeve (2) fitted into a case (7) is disclosed. Tree rotating shaft (3) rotates freely without contact with the sleeve (2) by means of dynamic pressure force generated by the lubricant fluid that fills the gap formed around the rotating shaft (3). An adhesive groove (2c) is formed around the entire outer circumferential surface of the sleeve (2). At least one hole (7a) facing the adhesive groove (2c) is formed in case (7), and case (7) and sleeve (2) are; adhered by the injection of an adhesive (13) into adhesive groove (2c) from the hole (7a). The fluid dynamic pressure bearing, manufactured in this manner provides a high-quality bearing that is easy to construct, that can be adapted to low-cost manufacturing, and that can maintain dimensional and structural accuracy and in which the case (7) and sleeve (2) can be reliably adhered together with the adhesive (13).

Abstract: A hydrodynamic bearing having a bearing sleeve, a rotational shaft supported for rotation by the bearing sleeve, a bearing gap formed between the bearing sleeve and the rotational shaft, lubricating oil contained within the bearing gap, at least one hydrodynamic pressure-generating groove formed at an inner peripheral surface of the bearing sleeve; and an oil reservoir. The oil reservoir includes a gradually expanding section located in a position distanced from the pressure-generating groove and a first larger inner diameter, section located adjacently to the gradually expanding section. A second larger inner diameter section is located immediately below an opening of the bearing sleeve and an oil-repelling peripheral groove located between the first larger inner diameter section of the oil reservoir and the second larger inner diameter section.

Abstract: A shaft body 2 of a fluid dynamic bearing having a flange portion 4 at one end is supported rotatably via radial direction micro clearances by the sleeve 5 having a dynamic pressure generating groove 11 on the inner peripheral portion. A flange portion 4 is inserted between the lower end surface of the sleeve 5 and end plate 7. A dynamic pressure generating groove 12 is formed on the lower end surface of sleeve 5, and a dynamic pressure generating groove 13 is formed on the upper surface of the endplate 7. The lower end surface of the sleeve 5 and the upper surface of the flange portion 4, and the upper surface of the end plate 7 and the lower surface of the flange portion 4 are facing each other via respective thrust direction micro clearances. Sleeve 5 is inserted into the case 6 such that the upper end surface is projected from the upper end surface of the case 6.

Abstract: A fluid dynamic bearing mechanism that can ensure bearing rigidity, reduce shaft loss torque, reduce power consumption, stabilize axial rotation, and improve rotational accuracy is disclosed. The fluid dynamic bearing mechanism being suitable for use in a hard disk drive. In the fluid dynamic bearing mechanism (equipped with a bearing case, endplate, and shaft) a cylindrical hole of the bearing case is changed to a stepped cylindrical hole that has a large diameter part and a small diameter part. The shaft is changed to a stepped shaft that has a large diameter part and a small diameter part. On the outer circumference of either the large diameter part of the stepped cylindrical hole, or the large diameter part of the stepped shaft, a first dynamic pressure groove is be formed. On the outer circumference of either the small diameter part of the stopped cylindrical hole or the small diameter part of the stepped shaft, a second dynamic pressure groove is being formed.

Abstract: A fluid dynamic pressure bearing device includes a shaft member (5) and a bearing member (41), at least one of the shaft member or the bearing member being rotatable with respect to the other A shaft member-side annular member (13) is fixed with respect to the shaft member. The shaft member-side annular member includes a large-diameter rim portion and a small-diameter outer circumferential surface portion. A bearing member-side annular member (14) is fixed with respect to the bearing member. The bearing member-side annular member includes an inner circumferential large-diameter step portion, and a small-diameter inner circumferential surface portion.

Abstract: A hydrodynamic bearing having a bearing sleeve, a rotational shaft supported for rotation by the bearing sleeve, a bearing gap formed between the bearing sleeve and the rotational shaft, lubricating oil contained within the bearing gap, at least one hydrodynamic pressure-generating groove formed at an inner peripheral surface of the bearing sleeve; and an oil reservoir. The oil reservoir includes a gradually expanding section located in a position distanced from the pressure-generating groove and a first larger inner diameter, section located adjacently to the gradually expanding section. A second larger inner diameter section is located immediately below an opening of the bearing sleeve and an oil-repelling peripheral groove located between the first larger inner diameter section of the oil reservoir and the second larger inner diameter section.

Abstract: A fluid dynamic bearing having a shaft (12) and a bearing sleeve (11) rotatably supported relative to each other. At least one of the shaft and the bearing sleeve is made of steel or stainless steel made of by weight C: 0.6˜1.20%; Si: 1.0 or less; Mn: 1.0% or less; Cr: 10.5˜18.0%; Mo: 1.0% or less; S.: 0.03% or less; and Fe. The dynamic pressure bearing surface (20) is formed by ridges (22) remaining in between multiple dynamic pressure grooves (21) formed by electrochemical machining.

Abstract: The invention provides a special type bearing device that is insusceptible to damage, is light in weight, has a long service life and excellent wear resistance, is insusceptible to the effect of change in temperature, is easy to fabricate, and has little offensiveness towards mating members. Further, the same is capable of sufficiently retaining a lubricant such as oil and grease, and retaining the lubricant for a long period of time without the need of supplying oil during operation, thereby rendering it maintenance-free. That is, the special type bearing device as described above has an axial shaft, a pair of rotating bodies fixedly attached to the shaft, and a supporting body with which the rotating bodies are in contact, wherein any one of the shift, the rotating bodies, and the supporting body is made of RB ceramic or CRB ceramic.

Abstract: An electrochemical machining tool (1) for electrochemical machining includes an electrode body (11). The electrochemical machining tool (1) and associated method can conduct simultaneous electrochemical machining of at least two of a radial dynamic pressure generating groove (43), an axial dynamic pressure generating groove (44), and a removal of a burr (42) associated with an oil pool (41). Electrochemical machining is performed with groove machining electrodes (12, 13) and deburring electrodes (14). A sleeve (4) machined using the electrochemical machining tool (1) and associated method has the radial dynamic pressure generating groove (43), the axial dynamic pressure generating groove (44), and the deburred oil pool (41). The sleeve (4) can be used in a hydrodynamic pressure bearing for use in a spindle motor of a hard disk drive.

Abstract: A fluid dynamic bearing mechanism for a motor (1) suitable for use in a hard disk drive and having a compact and thin shape, high bearing rigidity, and high rotating accuracy, and which securely keeps the rotor member (6) in place against shocks, and allows the inspection of lubricant supply amount easily. A fluid dynamic bearing mechanism having a capillary seal part (12) on one end of lubricant supply part formed by a minute gap including dynamic pressure grooves (10) formed on a shaft member (5) or a bearing member (4) is provided. An annular member (13) is fitted on the shaft member at the location corresponding to the capillary seal part, another annular member (14) is fitted on the bearing member at the location corresponding to the capillary seal part, a taper or step (13a, 14a) is formed on the outer peripheral surface of the annular member on the shaft member side and the inner peripheral surface of the annular member on the bearing member side.

Abstract: A fluid dynamic pressure bearing is constituted in which a shaft member, including thrust plates 5 engaged with small-diameter portions at both ends of a shaft 1, is relatively rotatably combined with a bearing member via radial and axial dynamic pressure bearings. The bearing member includes a casing 3, a sleeve assembly body engaged to the casing 3, and seal rings 6 engaged to end portions of the casing 3. The sleeve assembly body is constituted by two or more sleeve elements 2 and a spacer sleeve element 4 coaxial with and sandwiched between the sleeve elements 2. Capillary seal portions 9 are formed between the thrust plates 5 and the seal rings 6. Highly accurate finishing of the dynamic pressure bearing portions, capillary seal portions, etc. can easily be accomplished by an easy, highly accurate processing, even if the shaft member or bearing member of a spindle motor becomes longer as a memory capacity of a memory device is increased.

Abstract: A spindle motor is formed so as to support a pivot of a rotor by a pair of open bearings. The open bearings thus constructed will be less expensive and simple structures, so that a manufacturing cost thereof is reduced compared to a conventional spindle motor using a pair of ball bearings with shields. Accordingly, a low-cost spindle motor can be provided.

Abstract: The invention provides a special type bearing device that is insusceptible to damage, is light in weight, has a long service life and excellent wear resistance, is insusceptible to the effect of change in temperature, is easy to fabricate, and has little offensiveness towards mating members. Further, the same is capable of sufficiently retaining a lubricant such as oil and grease, and retaining the lubricant for a long period of time without the need of supplying oil during operation, thereby rendering it maintenance-free. That is, the special type bearing device as described above has an axial shaft, a pair of rotating bodies fixedly attached to the shaft, and a supporting body with which the rotating bodies are in contact, wherein any one of the shift, the rotating bodies, and the supporting body is made of RB ceramic or CRB ceramic.

Abstract: A fluid dynamic bearing unit comprised of a plurality of modularized elements that are combined is provided with a case element 10, an end plate element 20, a first outer ring element 30, a second outer ring element 80, a flangeattached shaft element 40, and a spacer element 100. On the inner circumferential surface of the first outer ring element 30 and the inner circumferential surface of the second outer ring element 80, a first dynamic pressure groove 91 and a second dynamic pressure groove 92 are formed to generate dynamic pressure that supports a load in the radial direction. On the upper end surface of the second outer ring element 80 and on the upper surface of an end plate element 20, a third dynamic pressure groove 93 and a fourth dynamic pressure groove 94 are formed to generate dynamic pressure that supports a load in the axial direction. Lubricating oil is filled into the minute gaps corresponding to each of these dynamic pressure grooves.

Abstract: A motor that can prevent damages on the fluid dynamic bearing. A ball is press-fitted into the end surface of the shaft body, and the ball is disposed in such a manner that the tip portion of the ball comes to the higher position with respect to the end surface of the annular body. When the shaft is at rest, the ball abuts against the upper surface of the counter plate, and the end surface of the annular body is brought into a state of being raised from the upper surface of the counter plate, so that the situation in which the end surface of the annular body and the upper surface of the counter plate are brought into almost fully touch each other can be avoided. Therefore, when the operation is started, the circulation speed of a fluid increases and a fluid layer is quickly formed. As a consequent, the fluid circularity blocking action, which could be occurred in the relate art, is avoided, and generation of scratch caused by starting rotation in the tightly sticked state can be positively prevented.

Abstract: A fluid dynamic bearing is provided. A structure in which a shaft member and an annular member fitted about the shaft member are rotatably supported by a bearing member and an annular member on the bearing member has a fifth gap for storing a lubricating fluid and supplying it to a second gap below the annular member on the shaft member and a third gap around its outer periphery through a fourth gap. The fourth and fifth gaps are tapered to produce a capillary drawing force toward the third and second gaps, so that the lubricating fluid may be supplied effectively from the fifth gap to the second and third gaps. This makes it possible to suppress any sudden formation of a reduced pressure upon exposure to impact or vibration to prevent the leakage of any lubricating fluid caused by the generation of bubbles, while making up for the loss of any lubricating fluid by vaporization.