JP2007082339A - Fluid bearing device and manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fluid bearing device that can be manufactured at low cost and has a high level of cleanliness. <P>SOLUTION: A hub 10 having a disk mounting face 10d is formed by injection molding. A gate trace 18 is formed in the hub 10 in proximity to the outside diameter end of the lower end face 10c1 of its flange 10c by this injection molding. This gate trace 18 is closed by an adhesive 13 applied to the bond area between the hub 10 and a yoke 12. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a hydrodynamic bearing device that supports a shaft member so as to be relatively rotatable in a radial direction with a lubricating film of a fluid generated in a radial bearing gap, and a manufacturing method thereof. This type of bearing device includes information devices such as magnetic disk drive devices such as HDD, optical disk drive devices such as CD-ROM, CD-R / RW, DVD-ROM / RAM, and magneto-optical disk drive devices such as MD and MO. It can be suitably used for a small motor such as a spindle motor such as a polygon scanner motor of a laser beam printer (LBP), a color wheel motor of a projector, or a fan motor.

  In addition to high rotational accuracy, the various motors are required to have high speed, low cost, low noise, and the like. One of the components that determine the required performance is a bearing that supports the spindle of the motor. In recent years, the use of a fluid bearing having characteristics excellent in the required performance has been studied or actually used. .

  This type of hydrodynamic bearing includes a hydrodynamic bearing having a dynamic pressure generating portion for generating a dynamic pressure in the lubricating fluid in the bearing gap, and a so-called true circular bearing having no dynamic pressure generating portion (with a bearing cross section). It is roughly divided into a perfect circle bearing).

  For example, in a hydrodynamic bearing device incorporated in a spindle motor of a disk drive device such as an HDD, both a radial bearing portion that supports a shaft member in the radial direction and a thrust bearing portion that supports the shaft direction in a thrust direction may be configured by dynamic pressure bearings. is there. As a radial bearing portion in this type of hydrodynamic bearing device (dynamic pressure bearing device), for example, either the inner peripheral surface of the bearing sleeve or the outer peripheral surface of the shaft member facing the bearing sleeve is used as a dynamic pressure generating portion. It is known that a dynamic pressure groove is formed and a radial bearing gap is formed between both surfaces. Further, as the thrust bearing portion, for example, a dynamic pressure groove as a dynamic pressure generating portion is formed on the end surface of the bearing sleeve, and between the end surface of the bearing sleeve and the end surface of the flange portion of the shaft member opposed thereto. What forms a thrust bearing gap is known (see, for example, Patent Document 1).

When the hydrodynamic bearing device is used by being incorporated in a motor for a disk drive device such as an HDD, a disk hub for holding an information storage medium such as a magnetic disk is provided on the shaft member. A yoke made of a magnetic material for improving the magnetic efficiency between the rotor magnet and the stator coil is usually fixed at a position of the disk hub facing the stator coil provided on the fixed side of the motor. As means for fixing this type of yoke to the disk hub, for example, means using an adhesive is known (see, for example, Patent Document 2).
JP 2003-239951 A JP-A-2005-45924

  By the way, recently, in response to a request for lowering the price of information equipment, many proposals for reducing the manufacturing cost of the hydrodynamic bearing device have been made. For example, with the aim of reducing the material cost, the component parts of the hydrodynamic bearing device, for example, the resinization of the disk hub has been studied. Alternatively, injection molding of the resin molded product using a metal part as an insert part has been studied.

  When this type of resin molded product is injection-molded, generally, a gate for filling a molten resin into a cavity of a molding die is provided, and the molten resin is injected into the cavity from this gate. Then, after the molten resin in the cavity is cooled and solidified, the molded product is taken out by opening the mold. In the state before the mold opening, the molded product is connected to the gate solidified part formed in the gate, but by opening the mold, the gate solidified part is divided and a part of the gate solidified part is gated. It remains on the molded product side as a mark. Therefore, depending on the size and shape of the gate mark (gate solidified portion) remaining on the molded product side, for example, cutting is performed after molding to remove the gate solidified portion from the molded product.

  The gate solidified portion that becomes the gate trace and the gate removal trace that remains on the molded product side after the gate solidified portion is removed include a sectional surface formed at the time of gate cut and a removal processed surface formed at the time of removal processing. . Unlike the molded surface, these sectional surfaces and removal processed surfaces are exposed from the internal cross section of the resin molded product. For example, a part of the filler mixed in the resin material is exposed and filled from this surface. It becomes easy to drop off materials. The dropped filler or the like adheres to the surface of the housing or the like, and may be mixed as contamination in the lubricating oil filled in the bearing device when the bearing device is assembled. In particular, the contamination generated around the disc hub adheres to the disc surface, which may reduce the reading accuracy of the disc.

  An object of the present invention is to provide a hydrodynamic bearing device that can be manufactured at low cost and has high cleanliness.

  In order to solve the above-described problems, the present invention provides a shaft member, a hub portion provided integrally or separately with the shaft member, and a lubricating film of fluid generated in a radial bearing gap facing the outer peripheral surface of the shaft member. In a bearing having a radial bearing that is supported so as to be relatively rotatable in a direction, and a yoke that is made of a magnetic material and is adhesively fixed to the hub, the hub is injection-molded with resin, and is formed on the hub by injection molding. The hydrodynamic bearing device is characterized in that the gate mark is closed with an adhesive supplied to an adhesive fixing surface between the hub portion and the yoke. Here, the trace of the gate refers to a portion where the gate position when the molten resin is filled in the molding die can be discriminated from the molded product at the time of injection molding of the bearing member. For example, the resin solidified inside the gate at the time of injection molding Of these, the portion remaining on the surface of the molded product even after gate cutting is included. Alternatively, a gate removal trace formed when the remaining portion is removed by machining or the like is included.

  In order to solve the above problems, the present invention provides a shaft member comprising a shaft member, a hub portion provided integrally or separately with the shaft member, and a lubricating film of fluid generated in a radial bearing gap facing the outer peripheral surface of the shaft member. In a method of manufacturing a hydrodynamic bearing device comprising a radial bearing portion that supports a shaft in a radial direction and a yoke that is made of a magnetic material and is adhesively fixed to the hub portion, the hub portion is injection-molded with resin. And a bonding and fixing step in which the yoke is bonded and fixed to the hub portion formed in the injection molding step. In the bonding and fixing step, the gate mark formed by injection molding of the hub portion is bonded to the hub portion and the yoke. There is provided a method for manufacturing a hydrodynamic bearing device, characterized in that an adhesive is solidified in a state of being blocked by an adhesive supplied to a fixed surface.

  As described above, the gate mark formed on the surface of the hub portion by injection molding of the resin is blocked by the adhesive supplied to the adhesive fixing surface between the hub portion and the yoke. After bonding and fixing, the gate mark is sealed against the external space (outside air). Therefore, it is possible to avoid such a situation that the filler or the like falls off and adheres to the inside or the periphery of the bearing device as contamination from the gate mark (gate solidified portion or gate removal mark), and the cleanliness of the bearing device and its periphery can be improved.

  Further, according to such a configuration, the gate mark is closed as the hub portion and the yoke are bonded and fixed. For this reason, only the yoke used as a component of the hydrodynamic bearing device and the adhesive used for bonding and fixing the yoke are sufficient to block the gate mark. In addition to the injection molding process and adhesive fixing process of the hub part, the gate mark is separately provided. There is no need to add a process for blocking. Therefore, such a closing operation can be performed without causing an increase in cost.

  More preferably, the gate mark is on an adhesive fixing surface with the yoke. According to such a configuration, since the gate mark is reliably sealed by the adhesive supplied between the adhesive fixing surfaces of the yoke and the hub portion, it is possible to more reliably prevent the occurrence of contamination from the gate mark. .

  As described above, according to the present invention, it is possible to provide a hydrodynamic bearing device that can be manufactured at low cost and has high cleanliness.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS.

  FIG. 1 conceptually shows a configuration example of a spindle motor for information equipment incorporating a hydrodynamic bearing device 1 according to an embodiment of the present invention. The spindle motor is used in a disk drive device such as an HDD, and includes a hydrodynamic bearing device (dynamic pressure bearing device) 1 that supports a rotating member 3 having a shaft member 2 and a hub portion 10 in a non-contact manner so as to be relatively rotatable. For example, a stator coil 4 and a rotor magnet 5 which are opposed to each other via a gap in the radial direction, and a bracket 6 are provided. The stator coil 4 is attached to the outer periphery of the bracket 6, and the rotor magnet 5 is fixed to a yoke 12 provided on the outer diameter side of the hub portion 10. The bearing member 7 of the hydrodynamic bearing device 1 is fixed to the inner periphery of the bracket 6. Although not shown, the hub 10 holds one or more disks D as information recording media. In the spindle motor configured as described above, when the stator coil 4 is energized, the rotor magnet 5 is rotated by an exciting force generated between the stator coil 4 and the rotor magnet 5. The disk held by the portion 10 rotates integrally with the shaft member 2.

  FIG. 2 shows the hydrodynamic bearing device 1. The hydrodynamic bearing device 1 mainly includes a bearing member 7, a lid member 11 that closes one end of the bearing member 7, and a rotating member 3 that rotates relative to the bearing member 7 and the lid member 11. For the sake of convenience of explanation, of the openings of the bearing member 7 formed at both ends in the axial direction, the side closed by the lid member 11 will be described as the lower side, and the side opposite to the closed side will be described as the upper side.

  The bearing member 7 has a shape in which both ends in the axial direction are open. The sleeve portion 8 has a substantially cylindrical shape, and is positioned on the outer diameter side of the sleeve portion 8. The housing portion 9 is formed integrally with or separate from the sleeve portion 8. And.

  The sleeve portion 8 is formed in a cylindrical shape with a porous body made of, for example, a metal non-porous body or sintered metal. In this embodiment, the sleeve portion 8 is made of a sintered metal porous body mainly composed of copper and formed in a cylindrical shape. For example, the sleeve portion 8 is bonded to the inner peripheral surface 9c of the housing portion 9 (including loose bonding) or press-fitted. It is fixed by appropriate means such as (including press-fit adhesion) and welding (including ultrasonic welding). Of course, the sleeve portion 8 can be formed of a material other than metal, such as resin or ceramic.

  A region where a plurality of dynamic pressure grooves are arranged as a radial dynamic pressure generating portion is formed on the entire inner surface or a partial cylindrical region of the inner peripheral surface 8 a of the sleeve portion 8. In this embodiment, for example, as shown in FIG. 3, two regions where a plurality of dynamic pressure grooves 8a1 and 8a2 are arranged in a herringbone shape are formed apart from each other in the axial direction.

  As shown in FIG. 4, for example, as shown in FIG. 4, a region in which a plurality of dynamic pressure grooves 8 b 1 are arranged in a spiral shape is formed on the entire lower surface 8 b of the sleeve portion 8 or a partial annular region.

  The housing part 9 is formed in a substantially cylindrical shape with a metal material or a resin material. In this embodiment, the housing part 9 has a shape in which both ends in the axial direction are opened, and one end side is sealed with the lid member 11. As shown in FIG. 5, for example, as shown in FIG. 5, a region in which a plurality of dynamic pressure grooves 9a1 are arranged in a spiral shape is formed on the entire end surface (upper end surface) 9a on the other end side or a partial annular region. Is done. A tapered surface 9b is formed on the outer periphery of the upper portion of the housing portion 9 and gradually increases in diameter toward the upper side (the side opposite to the sealing side).

  The lid member 11 that seals the lower end side of the housing part 9 is made of metal or resin, and is fixed to a step part 9 d provided on the inner peripheral side of the lower end of the housing part 9. Here, the fixing means is not particularly limited. For example, means such as adhesion (including loose adhesion and press-fit adhesion), press-fit, welding (for example, ultrasonic welding), welding (for example, laser welding), combinations of materials and requirements Can be appropriately selected in accordance with the fixing strength, sealing performance, and the like.

  In this embodiment, the rotating member 3 includes a shaft member 2 that is inserted into the inner periphery of the sleeve portion 8, and a hub portion 10 that is provided at the upper end of the shaft member 2 and is disposed on the opening side of the bearing member 7. ing.

  The shaft member 2 is made of metal in this embodiment, and is formed separately from the hub portion 10. The outer peripheral surface 2 a of the shaft member 2 faces the dynamic pressure grooves 8 a 1 and 8 a 2 forming regions formed in the inner peripheral surface 8 a of the sleeve portion 8 in a state where the shaft member 2 is inserted into the inner periphery of the sleeve portion 8. Then, when the shaft member 2 rotates, radial bearing gaps of first and second radial bearing portions R1 and R2 described later are formed between the inner peripheral surface 8a (see FIG. 2).

  A flange portion 2b is separately provided at the lower end of the shaft member 2 as a retaining member. The flange portion 2b is made of metal and is fixed to the shaft member 2 by means such as screw connection. An upper end surface 2b1 of the flange portion 2b is opposed to a formation region of the dynamic pressure groove 8b1 formed on the lower end surface 8b of the sleeve portion 8, and a later-described gap is formed between the formation region of the dynamic pressure groove 8b1 when the shaft member 2 rotates. A thrust bearing gap of one thrust bearing portion T1 is formed (see FIG. 2). Further, a concave portion (annular groove in this embodiment) 2c is formed at the upper end of the shaft member 2, which will be described later, when the hub portion 10 is formed by resin injection molding using the shaft member 2 as an insert part. The concave portion 2 c functions as a retaining member for the shaft member 2 with respect to the hub portion 10.

  The hub part 10 projects to the outer diameter side from the disk part 10a that covers the opening side (upper side) of the bearing member 7, the cylindrical part 10b that extends downward in the axial direction from the outer peripheral part of the disk part 10a, and the cylindrical part 10b. And a disc mounting surface 10d formed at the upper end of the flange portion 10c. A disk (not shown) is fitted on the outer periphery of the disk portion 10a and placed on the disk mounting surface 10d. Then, the disc is held on the hub portion 10 by an appropriate holding means (such as a clamper) not shown.

  The hub portion 10 having the above-described configuration is formed by injection molding of a resin composition using a crystalline resin such as LCP, PPS, or PEEK, or an amorphous resin such as PPSU, PES, or PEI as a base resin. In this embodiment, the hub portion 10 is injection-molded using the shaft member 2 as an insert part. Also, fibrous or powder such as carbon fiber and glass fiber, whisker-like filler such as potassium titanate, scaly filler such as mica, carbon black, graphite, carbon nanomaterial, various metal powders, etc. A suitable amount of the conductive filler in the form of a base resin can be used depending on the purpose.

  A lower end surface 10a1 of the disk portion 10a is opposed to an upper end surface 9a (a dynamic pressure groove 9a1 formation region) provided on one end opening side of the housing portion 9, and will be described later between the upper end surface 9a when the shaft member 2 rotates. The thrust bearing gap of the second thrust bearing portion T2 is formed (see FIG. 2).

  An inner peripheral surface 10b1 of the cylindrical portion 10b is opposed to a tapered surface 9b provided at the upper end of the outer periphery of the housing portion 9, and has a tapered shape in which the radial dimension gradually decreases upward between the tapered surface 9b. A seal space S is formed. The seal space S communicates with the outer diameter side of the thrust bearing gap of the thrust bearing portion T2 when the hub portion 10 (the rotating member 3) rotates. In a state where the lubricating oil described later is filled in the hydrodynamic bearing device 1, the oil level of the lubricating oil is always within the range of the seal space S.

  Here, the hub part 10 is formed through the following injection molding processes, for example.

  FIG. 6 exemplifies one form of the injection molding process of the hub part 10, and the molds 14 and 15 for molding the hub part 10 and the molds 14 and 15 are clamped between the molds 14 and 15. A cavity 16 having a shape corresponding to the hub portion 10 and a gate 17 for filling the cavity 16 with a molten resin are provided. In this embodiment, the gate 17 has an annular shape (for example, a film gate) and is provided in the vicinity of the outer edge of the lower end surface 10c1 of the flange portion 10c. During the injection molding of the hub portion 10, the shaft member 2 is disposed at a predetermined position in the molding dies 14 and 15 as an insert part, but is omitted in FIG.

  After the molten resin P is filled into the cavity 16 from the gate 17 and the molten resin P is solidified, the molds 14 and 15 are opened and the hub part 10 molded integrally with the shaft member 2 is taken out. As the mold is opened, the gate solidified portion formed in the gate 17 is automatically cut (or the gate solidified portion is cut by the gate cut mechanism), and a part of the gate solidified portion is located at the gate corresponding position of the hub portion 10. It remains as a gate mark 18.

  In this embodiment, the gate mark 18 is removed by machining or the like up to a position X in FIG. As a result, most of the gate trace 18 is removed, and a gate removal trace 19 as a part of the gate trace 18 remains on the lower end surface 10c1.

  A yoke 12 made of a magnetic material is bonded and fixed to the hub portion 10 molded as described above.

  In this embodiment, the yoke 12 is an annular member having a substantially L-shaped cross section, and includes an inner cylinder portion 12a and an outer diameter protrusion portion 12b protruding from one end of the inner cylinder portion 12a to the outer diameter side. In this embodiment, the outer diameter protruding portion 12b has a lower outer diameter side than the inner diameter side (other than the inner cylinder portion 12a) in order to adjust the axial position of the rotor magnet 5 fixed to the yoke 12 with respect to the stator coil 4. The shape is displaced to the end side. Therefore, as described later, the upper end surface 12b1 of the outer diameter protruding portion 12b contacts the hub portion 10 on the inner diameter side, and the lower end surface 12b2 contacts the rotor magnet 5 on the outer diameter side.

  The operation of bonding and fixing the yoke 12 having the above configuration to the hub portion 10 is performed, for example, as follows.

  In advance, the adhesive 13 is applied to the outer peripheral surface 10b2 of the cylindrical portion 10b serving as an adhesive fixing surface with the yoke 12 and the lower end surface 10c1 of the flange portion 10c. Then, the yoke 12 is inserted into the outer periphery of the cylindrical portion 10b of the hub portion 10 with the outer diameter protruding portion 12b disposed on the upper side, and the upper end surface 12b1 of the outer diameter protruding portion 12b is connected to the flange portion 10c. The lower end surface 10c1 is pressed. As a result, the adhesive 13 previously applied to the lower end surface 10c1 is spread from the application region to the periphery, and, for example, as shown in FIG. 8, the gate mark 18 (gate removal) is caused by the adhesive 13 extruded to the outer diameter side. A part of the trace 19) is sealed. Therefore, in this embodiment, a part of the inner diameter side of the gate removal trace 19 as the gate trace 18 is between the adhesive fixing surfaces (the upper end surface 12b1 and the lower end surface 10c1) of the hub portion 10 and the yoke 12. Sealed (closed) by the agent 13, and the remaining part (outer diameter side) is sealed (closed) by the adhesive 13 extruded from the adhesive fixing surface.

  By heating in this state and solidifying the adhesive 13, the adhesive fixing work between the hub portion 10 and the yoke 12 is completed.

  In this way, by adhering and fixing the gate trace 18 of the hub part 10 with the adhesive 13 applied to the lower end surface 10c1 of the hub part 10, in other words, at the time of injection molding of the hub part 10, By providing the gate 17 of the hub portion 10 in a region serving as an adhesive fixing surface between the hub portion 10 and the yoke 12, or in an area on the same plane as the adhesive fixing surface and where the adhesive 13 is spread, a gate mark 18 ( The gate removal trace 19) is sealed against the external space (outside air). Thereby, it is possible to avoid the situation where the filler and the like fall off and adhere to the inside and the periphery of the fluid bearing device 1 as contamination from the removal processing surface of the gate removal trace 19, and the cleanliness around the fluid bearing device 1 and the motor can be improved. .

  Further, since the closing operation of the gate trace 18 is performed at the same time as the fixing of the hub portion 10 and the yoke 12, nothing other than the yoke 12 or the adhesive 13 is required to close the gate trace 18. There is no need to add a separate process for closing the gate trace 18 before and after the adhesion fixing process. Therefore, the hub portion 10 (fluid bearing device 1) can be manufactured without increasing the cost.

  Further, in this embodiment, since the gate 17 is provided at a position corresponding to the vicinity of the disk mounting surface 10d of the cavity 16, for example, when the gate 17 is provided at a position corresponding to the surface of the cylindrical portion 10b of the cavity 16 or the like. In comparison, the moldability of the hub portion 10, particularly the moldability of the flange portion 10c having the disk mounting surface 10d can be improved. Thereby, the hub part 10 which raised the shaping | molding precision (flatness etc.) of the disk mounting surface 10d can be obtained.

  Various types of lubricating oil can be used as the fluid filled in the hydrodynamic bearing device 1, but the lubricating oil provided to the hydrodynamic bearing device for a disk drive device such as an HDD may be used at the time of use or transportation. Considering the temperature change in the above, an ester-based lubricating oil excellent in low evaporation rate and low viscosity, such as dioctyl sebacate (DOS), dioctyl azelate (DOZ), etc. can be suitably used.

  In the hydrodynamic bearing device 1 configured as described above, when the shaft member 2 rotates, the dynamic pressure grooves 8a1 and 8a2 forming regions formed in the inner peripheral surface 8a of the sleeve portion 8 are between the outer peripheral surface 2a of the opposing shaft member 2. A radial bearing gap is formed in As the shaft member 2 rotates, the lubricating oil in the radial bearing gap is pushed toward the axial center of the dynamic pressure grooves 8a1 and 8a2, and the pressure rises. As described above, the first radial bearing portion R1 and the second radial bearing portion R2 that support the shaft member 2 in a non-contact manner in the radial direction are configured by the dynamic pressure action of the lubricating oil generated by the dynamic pressure grooves 8a1 and 8a2. .

  At the same time, a thrust bearing gap between the lower end surface 8b of the sleeve portion 8 (region where the dynamic pressure groove 8b1 is formed) and the upper end surface 2b1 of the flange portion 2b facing the lower end surface 8b and the upper end surface 9a of the housing portion 9 are formed. The pressure of the lubricating oil film formed in the thrust bearing gap between the region where the dynamic pressure groove 9a1 is formed and the lower end surface 10a1 of the hub portion 10 opposite to the region is increased by the dynamic pressure action of the dynamic pressure grooves 8b1 and 9a1. The first thrust bearing portion T1 and the second thrust bearing portion T2 that support the rotating member 3 (hub portion 10) in a non-contact manner in the thrust direction are configured by the pressure of these oil films.

  Although one embodiment of the present invention has been described above, the present invention is not limited to this embodiment, and can also be applied to a hydrodynamic bearing device according to another configuration.

  In the above embodiment, the case where the gate trace 18 (gate removal trace 19) is provided near the outer diameter end of the lower end surface 10c1 of the flange portion 10c has been described. However, the gate trace 18 is blocked by the yoke 12, or As long as it is blocked by the adhesive 13 supplied to the adhesive fixing surface between the yoke 12 and the hub portion 10, it can be provided at an arbitrary location of the hub portion 10.

  For example, in the hub portion 10 shown in FIG. 2, the gate trace 18 (in other words, the entire area of the outer peripheral surface 10 b 2 of the cylindrical portion 10 b facing the inner cylindrical portion 12 a of the yoke 12 and the lower end surface 10 c 1 of the flange 12 c). A gate 17) can be provided at a position corresponding to the lower end surface 10c1 and the outer peripheral surface 10b2 of the cavity 16.

  Alternatively, even when the gate mark 18 is not directly sealed with the adhesive 13, there is a region around which the hub portion 10 and the yoke 12 are bonded and fixed with the adhesive 13. Thus, the gate trace 18 may be in a state of being indirectly sealed from the outside air (external space). For example, FIG. 9 shows an example, and the gate mark 18 is provided near the base of the cylindrical portion 10b and the flange portion 10c of the hub portion 10, and on the outer diameter side, the lower end surface 10c1 of the flange portion 10c. And the upper end surface 12 b 1 of the outer diameter protrusion 12 b of the yoke 12 are bonded and fixed with an adhesive 13. Further, below the gate mark 18, the outer peripheral surface 10 b 2 of the cylindrical portion 10 b and the inner peripheral surface 12 a 1 of the inner cylindrical portion 12 a are bonded and fixed with an adhesive 13.

  Further, in the above embodiment, the gate trace 18 is removed in consideration of the case where the gate trace 18 contacts the yoke 12 and the yoke 12, the hub portion 10, and the yoke 12 are not properly fixed to each other. However, as long as the gate trace 18 is formed at a position that does not hinder the adhesion and fixation between the hub portion 10 and the yoke 12, no particular removal process is required.

  Moreover, in the said embodiment, although the case where the hub part 10 was injection-molded integrally with the shaft member 2 by injection molding of resin which used the metal shaft member 2 as an insert part, for example, only the hub part 10 was resin-made. After the injection molding, the end portion of the metal shaft member 2 formed separately from the hub portion 10 can be integrated by being press-fitted into a hole provided in the center of the hub portion 10. Alternatively, the shaft member 2 can be made of resin, and the hub portion 10 and the shaft member 2 can be integrally formed by resin injection molding.

  In the above embodiment, the thrust bearing portions T1 and T2 are provided between the upper end surface 2b1 of the flange portion 2b and the lower end surface 8b of the sleeve portion 8 and between the hub portion 10 and the housing portion 9, respectively. As described above, the present invention is applicable regardless of the locations where the thrust bearing portions T1 and T2 are formed. That is, it does not matter whether or not the lower end surface 10a1 of the hub portion 10 forms a thrust bearing gap. For example, although illustration is omitted, both the thrust bearing portions T1 and T2 have both end surfaces of the flange portion 2b and these surfaces. It may be formed between the surface and the opposite surface.

  Further, the components of the hydrodynamic bearing device 1 excluding the hub portion 10 and the shaft member 2 need not be limited to the above embodiment. For example, although not shown in the drawings, the present invention is also applied to those in which the housing part 9 and the sleeve part 8 are integrally formed of the same material (the bearing member 7 is made into a single product) so as to be integrated between the respective components. Can be applied.

  In the above embodiment, the radial bearing portions R1 and R2 and the thrust bearing portions T1 and T2 are exemplified by the configuration in which the dynamic pressure action of the lubricating oil is generated by the dynamic pressure grooves having a herringbone shape or a spiral shape. However, the present invention is not limited to this.

  For example, although not shown as radial bearing portions R1 and R2, a so-called step-like dynamic pressure generating portion in which axial grooves are formed at a plurality of locations in the circumferential direction, or a plurality of circular arc surfaces in the circumferential direction. A so-called multi-arc bearing in which wedge-shaped radial gaps (bearing gaps) are formed between the shaft member 2 and the opposite circular outer peripheral surface 2a may be employed.

  Alternatively, the inner peripheral surface 8a of the sleeve portion 8 is a perfect circular outer peripheral surface not provided with a dynamic pressure groove or a circular arc surface as a dynamic pressure generating portion, and the perfect outer periphery of the shaft member 2 facing the inner peripheral surface 8a. A so-called perfect circle bearing can be constituted by the surface 2a.

  In addition, one or both of the first thrust bearing portion T1 and the second thrust bearing portion T2 are also omitted in the drawing, but the region where the dynamic pressure generating portion is formed (for example, the lower end surface 8b of the sleeve portion 8 and the housing portion 9). Is formed of a so-called step bearing or corrugated bearing (in which the step shape is a corrugated shape) in which a plurality of radial groove-shaped dynamic pressure grooves are provided at predetermined intervals in the circumferential direction. You can also.

  In the above embodiment, the radial dynamic pressure generating portion (dynamic pressure grooves 8a1 and 8a2) is provided on the sleeve portion 8 side, and the thrust dynamic pressure generating portion (dynamic pressure groove is provided on the sleeve portion 8 and housing portion 9 side. 8b1 and 9a1) have been described. The regions where the dynamic pressure generating portions are formed are, for example, the outer peripheral surface 2a of the shaft member 2 and the upper end surface 2b1 of the flange portion 2b, or the hub. It can also be provided on the lower end surface 10a1 side of the portion 10.

  In the above description, the lubricating oil is exemplified as the fluid that fills the inside of the hydrodynamic bearing device 1 and generates a dynamic pressure action in the radial bearing gap or the thrust bearing gap. A fluid capable of generating a pressure action, for example, a gas such as air, a fluid lubricant such as a magnetic fluid, or lubricating grease may be used.

It is sectional drawing of the spindle motor incorporating the hydrodynamic bearing apparatus which concerns on one Embodiment of this invention. It is sectional drawing of a hydrodynamic bearing apparatus. It is a longitudinal cross-sectional view of a sleeve part. It is the lower end surface of a sleeve part. FIG. 6 is an end view of the housing portion as viewed from the direction of arrow A. It is a figure which shows notionally the injection molding process of a hub part. It is an expanded sectional view showing the gate mark circumference of a hub part. It is an expanded sectional view showing the adhesion fixed surface periphery of a hub part and a yoke. It is an expanded sectional view showing the circumference of the gate mark concerning other forms.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fluid dynamic bearing apparatus 2 Shaft member 3 Rotating member 4 Stator coil 5 Rotor magnet 6 Bracket 7 Bearing member 8 Sleeve part 8a1, 8a2, 8b1 Dynamic pressure groove 9 Housing part 9a1 Dynamic pressure groove 10 Hub part 10c Gutter part 10c1 Lower end surface 12 Yoke 13 Adhesives 14, 15 Mold 16 Cavity 17 Gate 18 Gate mark 19 Gate removal mark S Seal space R1, R2 Radial bearing part T1, T2 Thrust bearing part

Claims (3)

A shaft member, a hub portion provided integrally or separately with the shaft member, and a fluid lubricating film formed in a radial bearing gap facing the outer peripheral surface of the shaft member support the shaft member so as to be relatively rotatable in the radial direction. In a hydrodynamic bearing device including a radial bearing portion and a yoke made of a magnetic material and bonded and fixed to the hub portion,
The hub portion is injection-molded with resin, and a gate mark formed on the hub portion by the injection molding is closed with an adhesive supplied to an adhesive fixing surface between the hub portion and the yoke. Fluid bearing device.   The hydrodynamic bearing device according to claim 1, wherein the gate mark is on an adhesive fixing surface with the yoke. A shaft member, a hub portion provided integrally or separately with the shaft member, and a lubricating film of fluid generated in a radial bearing gap facing the outer peripheral surface of the shaft member are supported so as to be relatively rotatable in the radial direction. In a method of manufacturing a hydrodynamic bearing device including a radial bearing portion and a yoke made of a magnetic material and bonded and fixed to the hub portion,
An injection molding step of injection molding the hub portion with a resin, and an adhesive fixing step of adhesively fixing the yoke to the hub portion molded in the injection molding step,
In the bonding and fixing step, the gate mark formed by injection molding of the hub portion is solidified in a state where the gate mark is closed with an adhesive supplied to the bonding and fixing surface of the hub portion and the yoke. A method for manufacturing a hydrodynamic bearing device.

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