Abstract: A weld line formed by injection molding of a sealing member is formed at a circumferential position out of deepest portions of axial grooves, which form thinned portions of the sealing member (optimally, in a region of a cylindrical surface between the axial grooves in a circumferential direction). Thus, the sealing member is prevented from being provided with parts having locally markedly low strength, and hence damage to be caused by press-fitting is prevented.

Abstract: A weld line formed by injection molding of a sealing member is formed at a circumferential position out of deepest portions of axial grooves, which form thinned portions of the sealing member (optimally, in a region of a cylindrical surface between the axial grooves in a circumferential direction). Thus, the sealing member is prevented from being provided with parts having locally markedly low strength, and hence damage to be caused by press-fitting is prevented.

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: An oil film is formed in a radial bearing clearance of a first radial bearing portion (R1) and a second radial bearing portion (R2) so as to rotatably support a shaft member (2). A bearing sleeve (8) and the shaft member (2) are accommodated in a housing (7), and the housing (7) has an inner space filled with a lubricant oil and has an opening sealed by a seal member (9). A first seal space (S1) is formed by means of an inner peripheral surface (9a2) of the seal member (9). The housing (7) and the seal member (9) are formed through injection molding of a resin.

Abstract: Disclosed is a fluid lubrication bearing device in which generation of a contaminant in a resin housing is suppressed, maintaining a high level of cleanliness in the interior and in the periphery of the bearing device. A side portion 7a and a bottom portion 7b of a housing 7 are formed integrally by injection molding of a resin material, and a gate mark 12 of a gate resin portion 11 formed at a lower end surface 7d of the bottom portion 7b of the molding is formed by a jig 13 having a forming surface 13a with a concave configuration. As a result, the cut portion 12a of the gate mark with sharp asperities is smoothened, and the surface 12d of the gate mark 12 is turned into a smooth convex curved surface.

Abstract: A weld line formed by injection molding of a sealing member is formed at a circumferential position out of deepest portions of axial grooves, which form thinned portions of the sealing member (optimally, in a region of a cylindrical surface between the axial grooves in a circumferential direction). Thus, the sealing member is prevented from being provided with parts having locally markedly low strength, and hence damage to be caused by press-fitting is prevented.

Abstract: The present invention aims to achieve a reduction in cost for a fluid dynamic bearing device. The fluid dynamic bearing device supports a shaft member (2) radially in a non-contact fashion by a dynamic pressure action generated in a radial bearing gap between an outer peripheral surface of the shaft member (2) and an inner peripheral surface (7a) of a bearing member (7), and is composed of the shaft member (2), the bearing member (7), a cover member (8), and a seal member (9). The shaft member (2) is inserted into an inner periphery of the bearing member (7), and an opening at a lower end thereof is sealed by the cover member (8). The seal member (9) is attached to an opening at an upper end of the bearing member (7), forming a seal space (S) between itself and the outer peripheral surface of the shaft member (2). Dynamic pressure grooves (G) of radial bearing portions (R1 and R2) are formed in an inner peripheral surface (7a) of the bearing member (7) by molding.

Abstract: A fluid dynamic bearing device includes a housing injection molded with a bearing sleeve as an insert. Accordingly, the molding of the housing and the assembly of the housing and the bearing sleeve can be performed in a single step. In addition to this, by simply increasing the die precisions the housing and the bearing sleeve can be fixed easily with high precision. Since the housing is opened at both ends, it is possible to sandwich the bearing sleeve, and accordingly, the bearing sleeve can be accurately positioned inside the dies with reliability.

Abstract: An outer peripheral surface (8d) of a bearing sleeve (8) is formed on a radially inside with respect to a first dynamic pressure generation portion (B1). In this case, it is possible to reduce a thickness of the bearing sleeve (8) while securing a first thrust dynamic pressure generating portion (B1) which has a thrust load capacity equivalent to that in a conventional case where a thrust dynamic pressure generating portion is formed in an end surface of the bearing sleeve. Accordingly, it is possible to reduce the thickness of the bearing sleeve (8) without sacrificing a bearing performance in a thrust direction. With this structure, a total amount of a lubricating oil sealed in a bearing device can be reduced, thereby reducing a capacity of a buffering function so as to downsize a sealing portion (9), and by extension, downsizing a fluid dynamic bearing device (1).

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: A hub (10) is a product formed by injection molding of a resin together with a core metal (13) as an inserted component, and the core metal (13) is exposed on a surface of the hub (10). With this configuration, a cavity of a die for molding the hub (10) is not divided by the core metal (13), and hence it is possible to suppress deterioration in fluidity of a resin due to arrangement of the core metal (13) in the cavity.

Abstract: An outer peripheral surface (8d) of a bearing sleeve (8) is formed on a radially inside with respect to a first dynamic pressure generation portion (B1). In this case, it is possible to reduce a thickness of the bearing sleeve (8) while securing a first thrust dynamic pressure generating portion (B1) which has a thrust load capacity equivalent to that in a conventional case where a thrust dynamic pressure generating portion is formed in an end surface of the bearing sleeve. Accordingly, it is possible to reduce the thickness of the bearing sleeve (8) without sacrificing a bearing performance in a thrust direction. With this structure, a total amount of a lubricating oil sealed in a bearing device can be reduced, thereby reducing a capacity of a buffering function so as to downsize a sealing portion (9), and by extension, downsizing a fluid dynamic bearing device (1).

Abstract: To achieve an increase in bearing stiffness and cost reduction, an oil film is formed in a radial bearing clearance of a first radial bearing portion (R1) and a second radial bearing portion (R2) so as to rotatably support a shaft member (2). A bearing sleeve (8) and the shaft member (2) are accommodated in a housing (7), and the housing (7) has an inner space filled with a lubricant oil and has an opening sealed by a seal member (9). A first seal space (S1) is formed by means of an inner peripheral surface (9a2) of the seal member (9). The housing (7) and the seal member (9) are formed through injection molding of a resin.

Abstract: A fluid dynamic bearing device is mainly composed of a housing, a bearing sleeve, and a rotary member. The housing is formed by a side portion formed through injection molding of a resin material, and a bottom member fixed to a fixing portion provided in the inner periphery at one axial end of the side portion and adapted to close an opening at one axial end of the side portion. The fixing portion is a molding surface formed through solidification, in conformity with the inner surface of the mold, of the resin injected by the injection molding.

Abstract: The present invention aims to achieve a reduction in cost for a fluid dynamic bearing device. The fluid dynamic bearing device supports a shaft member (2) radially in a non-contact fashion by a dynamic pressure action generated in a radial bearing gap between an outer peripheral surface of the shaft member (2) and an inner peripheral surface (7a) of a bearing member (7), and is composed of the shaft member (2), the bearing member (7), a cover member (8), and a seal member (9). The shaft member (2) is inserted into an inner periphery of the bearing member (7), and an opening at a lower end thereof is sealed by the cover member (8). The seal member (9) is attached to an opening at an upper end of the bearing member (7), forming a seal space (S) between itself and the outer peripheral surface of the shaft member (2). Dynamic pressure grooves (G) of radial bearing portions (R1 and R2) are formed in an inner peripheral surface (7a) of the bearing member (7) by molding.

Abstract: A fluid dynamic bearing device capable of exercising high bearing performance is provided at low cost. A housing 7 is injection molded with a bearing sleeve 8 as an insert. Accordingly, the molding of the housing 7 and the assembly of the housing 7 and the bearing sleeve 8 can be performed in a single step. In addition to this, by simply increasing the die precisions the housing 7 and the bearing sleeve 8 can be fixed easily with high precision. Since the housing 7 is opened at both ends, it is possible to sandwich the bearing sleeve 8, and accordingly, the bearing sleeve 8 can be accurately positioned inside the dies with reliability.

Abstract: Disclosed is a fluid lubrication bearing device in which generation of a contaminant in a resin housing is suppressed, maintaining a high level of cleanliness in the interior and in the periphery of the bearing device. A side portion 7a and a bottom portion 7b of a housing 7 are formed integrally by injection molding of a resin material, and a gate mark 12 of a gate resin portion 11 formed at a lower end surface 7d of the bottom portion 7b of the molding is formed by a jig 13 having a forming surface 13a with a concave configuration. As a result, the cut portion 12a of the gate mark with sharp asperities is smoothened, and the surface 12d of the gate mark 12 is turned into a smooth convex curved surface.

Abstract: A fluid dynamic bearing device is mainly composed of a housing, a bearing sleeve, and a rotary member. The housing is formed by a side portion formed through injection molding of a resin material, and a bottom member fixed to a fixing portion provided in the inner periphery at one axial end of the side portion and adapted to close an opening at one axial end of the side portion. The fixing portion is a molding surface formed through solidification, in conformity with the inner surface of the mold, of the resin injected by the injection molding.