Abstract: In a hydrodynamic bearing device in which a radial bearing face having a dynamic pressure generating groove on a shaft or an inner periphery of a sleeve is provided and a clearance between the shaft and the sleeve is filled with lubricant, an annular depression is provided on one end face of the sleeve adjacent to a rotor hub and a cover plate for covering the depression is attached to the sleeve so as to define a reservoir for the lubricant or air for the purpose of preventing such a risk that absence of an oil film occurs in clearances of a bearing of the hydrodynamic bearing device due to outflow of oil upon forcing of the oil by air received into the bearing. A step portion is provided on the other end face of the sleeve such that the step portion and the reservoir are communicated with each other by a communication hole. During operation of the hydrodynamic bearing device, air in the hydrodynamic bearing device reaches the reservoir via the communication hole so as to be discharged from the reservoir.

Abstract: The present invention aims to improve the efficiency of a clamping step for combining a flange with a shaft and to improve productivity. The shaft and the flange are previously tentatively combined in the tentative clamping step. In the tentative clamping step, a concave part at the end of the shaft is pressurized by a metal mold such as a ball to be enlarged to an outer circumferential direction, and then, pressurizing this concave part against the inner circumference of the flange, the concave part is fixed. The combined body made by tentatively combining the shaft and the flange is strongly combined in a proper clamping step. In order to correct a distortion such as a warpage of the flange that has been solidly combined by the proper clamping step, sandwiching the flange by the upper and lower metals, the flange is pressurized and a flash molding is carried out.

Abstract: The present invention provides a small and thin spindle motor in which no uneven pressure is applied to a recording medium when the recording medium is fixed to a hub, a disc driving apparatus having the spindle motor, and a production method thereof. The spindle motor comprises: a sleeve which is supported by a fixed shaft and rotates around a predetermined axis; and a hub provided on an outer peripheral portion of the sleeve, which includes: a tubular portion to be inserted into a central hole of a recording medium having a disc shape, which is coaxial with the sleeve and has a male thread formed on an outer peripheral surface; and a first receiving surface which is connected to the tubular portion and which holds the recording medium to the axis.

Abstract: An object of the present invention is to provide a hydrodynamic bearing device having a high reliability which can achieve miniaturization and reduction of weight and thickness, and a motor and a disc driving apparatus using the same. In the hydrodynamic bearing device according to the present invention, a sleeve through which a shaft penetrates has a first opposing surface substantially orthogonal to a central axis of the shaft at one end and has a second opposing surface at the other end. A thrust plate having a disc shape which is fixed near one end of the shaft or which is integrally formed with the shaft is positioned so as to oppose the first opposing surface of the sleeve. A seal plate positioned near the other end of the shaft is positioned with a gap to the second opposing surface of the sleeve.

Abstract: An object of the present invention is to provide a thermosetting resin composition which is acquired an excellent flame-retardancy without using any of halogen-based flame retardants, phosphorus-based flame retardants and antimony-based flame retardants and further without deteriorating chemical or physical properties which the thermosetting resin originally has.

Abstract: A motor has a stator having a plurality of teeth for receiving windings, a yoke connected to each tooth, and a rotor having permanent magnets facing the stator. An inner wall surface of each tooth faces the rotor with an air-gap therebetween. Each tooth is separated from an adjacent tooth by a slot-open-section extending between a tailing end of the tooth and a leading end of the adjacent tooth. The inner wall surface of each tooth has an arc extending from a center of the slot-open-section toward the tailing end. The air-gap at the tailing end of each tooth is greater than the air-gap at the leading end of each tooth. The inner wall surface of each tooth includes a straight-line tailing section extending from the center of the slot-open-section toward the leading end. The straight-line tailing section extends tangentially from the arc.

Abstract: This invention pertains to a rotor core (6) in which a plurality of core sheets (1) are laminated on one another on a rotor shaft (4). A plurality of slits (3, 7) and a plurality of strips (2) are alternately arranged in a radial direction of each of the core sheets (1) so as to convexly confront a center of each of the core sheets (1) such that an outer peripheral rim (10) is formed between an outer peripheral edge of each of the core sheets (1) and each of opposite ends of each of the slits (3, 7). A stress concentration portion (11) which is provided at a portion (10a) of the outer peripheral rim (10) and has a width (L1) larger than that of the remaining portions of the outer peripheral rim (10).

Abstract: This invention pertains to a rotor core (6) in which a plurality of core sheets (1) are laminated on one another on a rotor shaft (4). A plurality of slits (3, 7) and a plurality of strips (2) are alternately arranged in a radial direction of each of the core sheets (1) so as to convexly confront a center of each of the core sheets (1) such that an outer peripheral rim (10) is formed between an outer peripheral edge of each of the core sheets (1) and each of opposite ends of each of the slits (3, 7). A stress concentration portion (11) which is provided at a portion (10a) of the outer peripheral rim (10) and has a width (L1) larger than that of the remaining portions of the outer peripheral rim (10).