JP5143435B2 - Manufacturing method of shaft member for hydrodynamic bearing device, and shaft member manufactured by the method - Google Patents

Description

  The present invention relates to a method for manufacturing a shaft member for a hydrodynamic bearing device, and a shaft member manufactured by the method.

  The hydrodynamic bearing device supports a shaft member in a relatively rotatable manner with a fluid film formed in a bearing gap. This type of bearing device is particularly excellent in rotational accuracy, quietness, etc. during high-speed rotation, and is suitably used as a bearing device for motors mounted on various electrical devices including information devices. Specific examples of suitable applications include spindle motors in magnetic disk devices such as HDD, optical disk devices such as CD-ROM, CD-R / RW, and DVD-ROM / RAM, and magneto-optical disk devices such as MD and MO. And a bearing device for a motor such as a polygon scanner motor of a laser beam printer (LBP), a color wheel motor of a projector, and a fan motor.

  Usually, in this type of hydrodynamic bearing device, it is known that the shaft portion of the shaft member is inserted into the inner periphery of a bearing sleeve or the like and forms a radial bearing portion between the inner peripheral surface of the opposing bearing sleeve. Yes. Further, there is known a structure in which a flange portion is provided at one end of a shaft portion, and a thrust bearing portion is formed between an end surface of the flange portion and a surface facing the flange portion (for example, an end surface of a bearing sleeve). Reference 1).

  Thus, since the outer peripheral surface of the shaft portion constitutes a radial bearing portion and the end surface of the flange portion constitutes a thrust bearing portion, these surfaces need to be finished with high accuracy. At the same time, when the radial bearing part and the thrust bearing part are both configured, not only the individual surface accuracy but also the shape accuracy between them, that is, the perpendicularity between the outer peripheral surface of the shaft portion and the end surface of the flange portion is important. It becomes.

  As a method for integrating the shaft portion and the flange portion which are separate from each other at low cost, for example, means for press-fitting and fixing an annular thrust plate to the fixed shaft has been proposed (see Patent Document 2).

In addition, as a means for press-fitting and fixing the shaft portion and the flange portion with high accuracy, a guide member in which the perpendicularity between the shaft holding surface and the ring contact surface is processed with high accuracy in advance is used, and at the start of press-fitting, they are mutually applied. There has been proposed one that performs press-fitting and fixing using an R portion provided on the outer periphery of the lower end of the shaft member (shaft portion) in contact and a chamfered portion provided on the inner periphery of the upper end of the hole of the ring member (flange portion) (patent) Reference 3). In this case, the R portion provided at the lower end of the shaft member first contacts the chamfered portion of the hole of the ring member, and the ring member moves in the horizontal direction by the action, so that the shaft member and the ring member are coaxially fitted and press-fitted. Is to be done.
JP 2003-239951 A JP 2000-324753 A JP 2001-287124 A

  As described above, when integrating the shaft portion and the flange portion by press-fitting, if the shape accuracy (perpendicularity) between the bearing surfaces is increased, the press-fitting dimension (the press-fitting length in the axial direction) should be increased. Good. However, in recent situations where demands for downsizing are intensifying, it is unavoidable to reduce the axial dimension of the shaft member, and it is very difficult to increase the press-fit dimension.

  In addition, considering that this type of shaft member is a mass-produced product, dimensional variations of shaft portions and flange portions manufactured separately must be allowed to some extent. Assuming this, even if the press-fitting is performed using a guide member in which the perpendicularity between the shaft holding surface and the ring contact surface is processed with high accuracy in advance as in Patent Document 3, the shaft portion It is difficult to press-fit in a state where the position and posture with respect to the flange portion are maintained with high accuracy.

  In addition, since the press-fitting is performed with the deformation of the members, even if the press-fitting is positioned with high accuracy, the positional relationship often collapses as the press-fitting is performed. Since the guide member described in Patent Document 3 is connected to a drive mechanism (screw shaft) via a spring, the guide member does not descend below the position in contact with the flange portion even when press-fitting of the shaft portion starts. It is configured as follows. However, this guide member is merely for positioning the flange portion with respect to the shaft portion at the start of press-fitting, and is not intended to prevent or repair the positional relationship after press-fitting starts.

  In view of the above circumstances, an object of the present invention is to mass-produce a shaft member for a hydrodynamic bearing device excellent in bearing surface accuracy and shape accuracy between bearing surfaces at low cost.

In order to solve the above-mentioned problems, the present invention includes a shaft portion and a flange portion that is press-fitted and fixed to one end of the shaft portion, and a radial bearing between the outer peripheral surface of the shaft portion and a surface facing the outer peripheral surface. A hydrodynamic bearing that forms a gap and forms a thrust bearing gap between an end face of the flange portion and a face facing the end face, and is supported by a film of fluid formed in the radial bearing gap and the thrust bearing gap. In the manufacturing method of the shaft member for an apparatus , the flange portion is held in the thickness direction between the first jig that holds the shaft portion inserted in the inner peripheral surface and the first jig. A second jig that contacts the other end of the shaft portion, presses the shaft portion toward the flange portion, and a third jig disposed between the first jig and the pressing member. The jig is disposed between the jig, the first jig, and the third jig. And an elastic body that transmits the load to the first jig with compression when receiving a load directed toward the flange portion, and presses the shaft portion toward the flange portion by contacting the pressing member. start the press-fitting of the shaft part relative to the hole provided in the flange portion by lowering, at the stage of press-fitting position against the flange portion of the shaft portion is stabilized, further the pressing member is brought into contact with the third jig press As a result, the insertion of the shaft portion into the hole provided in the flange portion is advanced, and the flange portion is sandwiched and compressed by the first jig and the second jig, thereby correcting the posture of the flange portion with respect to the shaft portion. method for producing a fluid bearing device for a shaft member, wherein the Turkey be imparted to the flange portion corrective force to provide.

In order to solve the above-mentioned problem, the present invention includes a shaft portion and a flange portion that is press-fitted and fixed to one end of the shaft portion, and between the outer peripheral surface of the shaft portion and a surface facing the outer peripheral surface. A radial bearing gap is formed, and a thrust bearing gap is formed between the end surface of the flange portion and a surface opposite to the end surface, and is rotationally supported by a fluid film formed in the radial bearing gap and the thrust bearing gap. In the method for manufacturing a shaft member for a hydrodynamic bearing device , the flange portion is sandwiched in the thickness direction between the first jig and the first jig that hold the shaft portion inserted in the inner peripheral surface. The second jig held in contact with the other end of the shaft portion, the first pressing member that pushes the shaft portion toward the flange portion, and the other end of the first jig, And a second pressing member that pushes the jig toward the negative flange portion. Is allowed to start the press-fitting of the shaft part relative to the hole provided in the flange portion by pressing down on the side of the flange portion of the shaft portion, at the stage of press-fitting position against the flange portion of the shaft portion is stabilized, the second pressing By pressing the member in contact with the first jig, the press-fitting of the shaft part into the hole provided in the flange part is advanced, and the flange part is sandwiched between the first jig and the second jig. Provided is a method for manufacturing a shaft member for a hydrodynamic bearing device, wherein the shaft member is compressed to apply a correcting force to the flange portion to correct the posture of the flange portion with respect to the shaft portion.

  As described above, the present invention is characterized by correcting the shaft portion and the flange portion in the press-fitting process or in the press-fitting completion state. That is, by performing correction at a stage where the press-fitting has progressed to a certain degree or at a stage where the press-fitting is completed, avoiding the start of press-fitting, it is possible to appropriately correct the deformation caused by the press-fitting or the distortion of the posture. Therefore, it is possible to manufacture a shaft member for a hydrodynamic bearing device that is excellent in accuracy of the bearing surface provided in the shaft portion and the flange portion and excellent in the perpendicularity between the bearing surface of the shaft portion and the bearing surface of the flange portion at low cost. Is possible.

  Further, if the correction force is applied after completion of press-fitting, the mechanism used for press-fitting and the mechanism used for correction can be made separate. According to this, a correction force having a magnitude suitable for correction (for example, a load equal to or larger than the load required for press-fitting) can be applied to the flange portion and the like without being limited by the pressure input, It becomes possible to increase the degree of freedom of form.

  Further, if the correction force is applied in the press-fitting process, the press-fitting and the correction can be performed in the same process, and thereby the number of processes can be reduced. Further, depending on the configuration of the apparatus, a drive system (drive mechanism) used for press-fitting the shaft portion can be used (shared) as a drive system used for correcting the flange portion and the like, and only one drive system is required. Therefore, it becomes possible to simplify the necessary facilities. Further, according to such a method, the posture of the flange portion with respect to the shaft portion is corrected during the press-fitting, so that the deformation (distortion from an appropriate position) caused by the press-fitting can be corrected in a small state. Accordingly, the correction can be performed with a correction force that is smaller than that applied when the press-fitting is completed.

Further, as described above, when the correction force is applied to the flange portion during the press-fitting of the shaft portion using the two pressing members , for example , the correction force applied to the flange portion is gradually increased as the press-fitting progresses. Thus, it is possible to correct the posture of the flange portion with respect to the shaft portion. When press-fitting is performed with correction force, the force required for press-fitting may increase depending on the correction mode and the size. On the other hand, as described above, if the press-fitting is performed while gradually increasing the correction force to the flange portion, the force required for the press-fitting can be reduced as a whole.

  The shaft member obtained by the above-described manufacturing method has excellent bearing surface accuracy and perpendicularity between the bearing surfaces, and also has good mass productivity. Therefore, it is necessary to manage the bearing gap with high accuracy. It can be suitably provided as a shaft member for a bearing device or as a fluid dynamic bearing device provided with this shaft member.

  As described above, according to the present invention, it is possible to mass-produce a shaft member for a hydrodynamic bearing device having excellent bearing surface accuracy and shape accuracy between bearing surfaces at low cost.

  Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. In the following description, the “up and down” direction is merely defined for easy understanding of the positional relationship between the components in each figure, and specifies the installation direction and usage mode of the hydrodynamic bearing device. is not. The same applies to the description of other configurations described later or the manufacturing process of the shaft member.

  FIG. 1 is a sectional view of a spindle motor equipped with a hydrodynamic bearing device 1 according to a first embodiment of the present invention. This spindle motor is used, for example, for an HDD having a magnetic disk, and is opposed to the hydrodynamic bearing device 1 that supports the shaft member 2 to which the hub 3 is attached in the radial direction in a non-contact manner, for example, via a radial gap. And a bracket 5. The drive unit 4 includes a stator coil 4 a and a rotor magnet 4 b. The stator coil 4 a is fixed to the bracket 5, and the rotor magnet 4 b is fixed to the hub 3. The housing 7 of the hydrodynamic bearing device 1 is fixed to the inner periphery of the bracket 5. Further, as shown in the figure, the hub 3 holds the disks 6 (two in FIG. 1). In the spindle motor configured as described above, when the stator coil 4a is energized, the rotor magnet 4b is rotated by the exciting force generated between the stator coil 4a and the rotor magnet 4b, and accordingly, is held by the hub 3. The disc 6 rotates integrally with the shaft member 2.

  FIG. 2 shows the hydrodynamic bearing device 1. The hydrodynamic bearing device 1 includes a housing 7, a bearing sleeve 8 fixed to the inner periphery of the housing 7, a lid member 9 that closes one end of the housing 7, and a seal disposed on the other end opening side of the housing 7. It mainly includes a member 10, a housing 7, a bearing sleeve 8, and a shaft member 2 that rotates relative to the seal member 10.

  The housing 7 is formed in a cylindrical shape with a metal material such as brass or a resin material, for example, and has a shape in which both ends in the axial direction are opened. The outer peripheral surface 8c of the bearing sleeve 8 is fixed to the inner peripheral surface 7a of the housing 7 by an appropriate means such as adhesion (including gap adhesion and press-fit adhesion), press-fitting, and welding (including ultrasonic welding and laser welding). Is done. A fixing surface 7b is formed at the lower end of the inner peripheral surface 7a and has a diameter larger than that of the inner peripheral surface 7a and for fixing a lid member 9 described later.

  The bearing sleeve 8 is formed in a cylindrical shape with a porous body made of sintered metal, for example. In this embodiment, the bearing sleeve 8 is made of a sintered metal porous body mainly composed of copper and formed in a cylindrical shape, and is bonded and fixed to the inner peripheral surface 7 a of the housing 7. Here, the bearing sleeve 8 can also be formed of a porous body made of a non-metallic material such as resin or ceramic, and has no internal pores or lubrication other than the porous body such as sintered metal. It can also be formed of a material having a structure with pores of such a size that oil cannot enter and exit.

A region in which a plurality of dynamic pressure grooves are arranged as a radial dynamic pressure generating portion is formed on the entire inner surface or a part of the cylindrical region of the inner peripheral surface 8 a of the bearing sleeve 8. In this embodiment, for example, as shown in FIG. 3, regions in which a plurality of dynamic pressure grooves 8a1 and 8a2 having different inclination angles are arranged in a herringbone shape are formed at two locations separated in the axial direction. In this embodiment, for the purpose of intentionally creating circulation of the lubricating oil inside the bearing, one (here, the upper side) dynamic pressure grooves 8a1 and 8a2 forming regions are formed asymmetrically in the axial direction. In the form illustrated in FIG. 3, the axial dimension X ₁ of the dynamic pressure groove 8 a ₁ formation area above the axial center m (the seal member 10 side) is the axial dimension of the lower dynamic pressure groove 8 a 2 formation area. It is formed to be larger than X _2.

  For example, as shown in FIG. 4, an area where a plurality of dynamic pressure grooves 8 b 1 are arranged in a spiral shape is formed as a thrust dynamic pressure generating portion on the entire lower surface 8 b of the bearing sleeve 8 or a partial annular region. This dynamic pressure groove 8b1 formation region is opposed to an upper end surface 22a of a flange portion 22 described later in the state of a finished product, and the first thrust bearing portion T1 described later is formed between the upper end surface 22a and the shaft member 2 when rotating. A thrust bearing gap is formed (see FIG. 2).

  A plurality of axial grooves 8 c 1 extending in the axial direction are formed on the outer peripheral surface 8 c of the bearing sleeve 8. These axial grooves 8c1 play a role in quickly recovering such a state to an appropriate state when the hydrodynamic bearing device 1 is used, such as when an excess or deficiency of lubricating oil occurs in the bearing internal space. .

  The lid member 9 that closes the lower end side of the housing 7 is formed of, for example, a metal material or a resin material, and is fixed to a fixing surface 7 b provided at the inner peripheral lower end of the housing 7. As the fixing means, as in the case of the bearing sleeve 8, any means such as adhesion, press-fitting, welding, and welding can be used.

  On the entire upper surface 9a of the lid member 9 or a partial annular region, a dynamic pressure groove forming region is formed as a thrust dynamic pressure generating portion, for example, having the same arrangement mode as in FIG. . This dynamic pressure groove forming region faces the lower end surface 22b of the flange portion 22 in the finished product state, and a thrust bearing gap of a second thrust bearing portion T2 described later between the lower end surface 22b when the shaft member 2 rotates. (See FIG. 2).

  In this embodiment, the sealing member 10 as a sealing means is formed of a metal material or a resin material separately from the housing 7, and is fixed to the inner periphery of the upper end of the housing 7 by any means such as press-fitting, bonding, welding, and welding. .

  A taper-shaped seal surface 10a is formed on the inner periphery of the seal member 10, and a seal space S is formed between the seal surface 10a and an outer peripheral surface of a shaft portion 21 described later. In a state where the lubricating oil is filled in the hydrodynamic bearing device 1, the oil level of the lubricating oil is always maintained within the range of the seal space S.

  The shaft member (fluid bearing device shaft member) 2 includes a shaft portion 21 and an annular flange portion 22 that is press-fitted and fixed to the lower end of the shaft portion 21. In this embodiment, as shown in FIG. 2, a radial bearing surface 21 a facing the dynamic pressure grooves 8 a 1, 8 a 2 forming region provided on the inner peripheral surface 8 a of the bearing sleeve 8 is provided on the outer periphery of the shaft portion 21 in the axial direction. Two places are provided apart. Between the radial bearing surfaces 21a and 21a, a pussie portion 21b having a smaller diameter than the radial bearing surface 21a is provided. The shaft portion 21 is formed of a relatively hard material such as SUS steel in consideration of strength and sliding characteristics, whereas the flange portion 22 is relatively soft such as brass mainly considering workability. Although it is good to form with a material, it is also possible to select the material of each member arbitrarily, without restricting to this combination separately.

  After assembling the above-described components, the bearing internal space is filled with lubricating oil to obtain the hydrodynamic bearing device 1 as a finished product. Here, as the lubricating oil filled in the hydrodynamic bearing device 1, various types can be used. However, the lubricating oil provided to the hydrodynamic bearing device for a disk drive device such as an HDD is used as the lubricating oil. Considering temperature changes during transportation or transportation, ester-based lubricating oils 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 of the bearing sleeve 8 face the radial bearing surfaces 21a and 21a of the shaft portion 21 via the radial bearing gap. To do. As the shaft member 2 rotates, the lubricating oil is pushed toward the axial center m of the dynamic pressure grooves 8a1 and 8a2 in any of the upper and lower dynamic pressure grooves 8a1 and 8a2 formation regions, and the pressure rises. By such dynamic pressure action of the dynamic pressure grooves 8a1 and 8a2, the first radial bearing portion R1 and the second radial bearing portion R2 that rotatably support the shaft member 2 in the radial direction are separated from each other in the axial direction. It is configured in two places.

  At the same time, the thrust bearing gap between the region where the dynamic pressure groove 8b1 is formed on the lower end surface 8b of the bearing sleeve 8 and the upper end surface 22a of the flange 22 opposite to this region, and the upper end surface 9a of the lid member 9 are provided. An oil film of lubricating oil is formed in the thrust bearing gap between the dynamic pressure groove forming region and the lower end surface 22b of the flange portion 22 facing this region by the dynamic pressure action of the dynamic pressure groove. The first thrust bearing portion T1 and the second thrust bearing portion T2 that support the shaft member 2 in the thrust direction in a non-contact manner are constituted by the pressure of these oil films.

  Hereinafter, an example of the manufacturing process of the shaft member 2 will be described with reference to FIG.

  The shaft member 2 having the above-described configuration is formed through a step of press-fitting the lower portion of the shaft portion 21 into the hole 22c provided in the flange portion 22 and a step of correcting the posture of the flange portion 22 with respect to the shaft portion 21 after completion of the press-fitting. The

  FIG. 5A to FIG. 5C conceptually show an example of a press-fitting process and a correction process with respect to the flange part 22 of the shaft part 21. For example, FIG. 5A shows the arrangement relationship between the shaft portion 21 and the flange portion 22 before press-fitting, and the shaft portion 21 is inserted into the cylindrical inner peripheral surface 31a of the first jig 31 and held. Has been. Further, the flange portion 22 is held between the lower end surface 31 b of the first jig 31 and the upper end surface 32 a of the second jig 32 positioned below the first jig 31.

  Here, the cylindrical inner peripheral surface 31 a and the lower end surface 31 b provided on the first jig 31 and the upper end surface 32 a provided on the second jig 32 are all in contact with the bearing surface of the shaft member 2. The surface accuracy and shape accuracy of these bearing surfaces are corrected. Therefore, it is important that the cylindrical inner peripheral surface 31a, the lower end surface 31b, and the upper end surface 32a are finished with high accuracy.

  Further, in this type of shaft member 2, in view of the fact that the perpendicularity between the radial bearing surface 21a and the thrust bearing surface (upper end surface 22a) affects the bearing performance, the cylindrical inner peripheral surface 31a and the lower end surface 31b It is desirable to increase the squareness between the two by machining with high accuracy in advance. Of course, both jigs 31 and 32 are processed and arranged with high precision so that a high degree of parallelism is obtained between the lower end surface 31b and the upper end surface 32a that restrain the flange portion 22 in the axial direction. . As an example, the inner diameter dimension of the cylindrical inner peripheral surface 31a is processed to be 3 μm to 7 μm larger than the outer diameter of the shaft portion 21 to be press-fitted. Further, the cylindrical inner peripheral surface 31a and the lower end surface 31b, and the perpendicular angle between the cylindrical inner peripheral surface 31a and the upper end surface 32a are processed to be 3 μm or less, and these jigs 31 and 32 are disposed. Is done.

  In the state before press-fitting, the outer diameter size of the shaft portion 21 is set larger than the inner diameter size of the hole 22c of the flange portion 22, and a value obtained by subtracting the inner diameter size of the hole 22c from the outer diameter size of the shaft portion 21 is obtained. This is a substantial press-fitting allowance. Here, for example, the dimension of each member is set so that the diameter of the press-fitting allowance is 10 μm or more and 30 μm or less, preferably 15 μm or more and 20 μm or less. In this embodiment, chamfered portions 21 d and 22 d are formed at the press-fit side end of the shaft portion 21 and the press-fit side end of the hole 22 c of the flange portion 22, respectively. As shown in FIG. 5A, the chamfered portion 21d provided on the shaft portion 21 comes into contact with the chamfered portion 22d provided on the flange portion 22 before the press-fitting.

  As described above, the shaft portion 21 and the flange portion 22 are placed in the first jig 31 and the second jig 32, and the first pressing member 33 is lowered by an appropriate drive mechanism, and the shaft portion 21 is moved. Is pressed (see FIG. 5B). As a result, press-fitting of the shaft portion 21 into the flange portion 22 is started. When the shaft portion 21 is pressed, the flange portion 22 is coaxially aligned with the shaft portion 21 (mainly in the horizontal direction) due to the interaction between the chamfered portion 21d of the shaft portion 21 and the chamfered portion 22d of the flange portion 22 that are in contact with each other. Is done.

  Thus, by pressing down the first pressing member 33, the shaft portion 21 is press-fitted into the hole 22c of the flange portion 22, and when the press-fitting of the shaft portion 21 is completed, the first pressing member 33 is pressed. Stops descending. In this embodiment, as shown in FIG. 5B, when the lower end surface 21c of the shaft portion 21 is press-fitted until it reaches the same height as the lower end surface 22b of the flange portion 22, the first pressing member. The pressing (press fitting) by 33 is stopped.

  Then, after the press-fitting is completed, the second pressing member 34 is disposed above the first jig 31 and the shaft portion 21 instead of the first pressing member 33, and the second pressing member 34 is lowered. Accordingly, the first jig 31 is pressed, and the flange portion 22 is compressed by the lower end surface 31b of the first jig 31 and the upper end surface 32a of the second jig 32 (see FIG. 5C). ). By performing the compression work in a state where the shaft portion 21 is held on the cylindrical inner peripheral surface 31a of the first jig 31, the posture of the flange portion 22 with respect to the shaft portion 21 follows the shape of the jigs 31 and 32. Will be corrected. Specifically, the perpendicularity between the radial bearing surfaces 21a and 21a and both end surfaces 22a and 22b having thrust bearing surfaces is improved (for example, improved to 5 μm or less). At the same time, both end surfaces 22a and 22b of the flange portion 22 are corrected, and the surface accuracy and shape accuracy (parallelism here) are improved.

  Thus, after press-fitting the shaft portion 21 into the flange portion 22, the correcting force is applied by the jigs 31 and 32, and the posture of the flange portion 22 with respect to the shaft portion 21 is corrected to cause the press-fit. Deformation and posture distortion can be corrected as appropriate. In particular, as in this embodiment, by applying a correction force to the flange portion 22, both end faces 22a and 22b of the flange portion 22 that are relatively susceptible to deformation due to differences in material and shape are effectively corrected. be able to. As described above, the shaft member 2 excellent in accuracy of the radial bearing surface 21a and the thrust bearing surfaces (both end surfaces 22a and 22b) provided in the shaft portion 21 and the flange portion 22 and excellent in the perpendicularity between these bearing surfaces is obtained. be able to.

  In this embodiment, the posture of the flange portion 22 relative to the shaft portion 21 is corrected after the press-fitting is completed. In this way, if correction is performed after completion of press-fitting, the mechanism used for press-fitting and the mechanism used for correction (particularly the drive mechanism) can be made separate. For example, from the load caused by the first pressing member 33 Also, a large load (correction force) can be applied to the flange portion 22. Thereby, it is possible to freely adjust the magnitude of the correction force, and an appropriate correction force according to the press-fitting mode and the size can be applied to the shaft portion 21 and the flange portion 22.

  In this embodiment, the correction is performed by applying a correction force to the press-fitted region of the flange portion 22 or the vicinity thereof. As described above, press-fitting is performed with deformation of at least one of the members, and local plastic deformation is likely to occur particularly in the press-fitted region. Therefore, the entire end surfaces 22a and 22b including the inner peripheral edge of the flange portion 22 that are in the press-fitted region or the vicinity thereof are compressed more effectively by compressing with the first jig 31 and the second jig 32. Thus, the deformation of the flange portion 22 itself and the fixing posture of the flange portion 22 with respect to the shaft portion 21 can be corrected with high accuracy.

  If correction is performed after completion of press-fitting as in this embodiment, the direction in which the correction force is applied and the configuration related to this step are arbitrary. For example, as shown in the drawing, by pressing the first jig 31 that holds the shaft portion 21 and the flange portion 22, the flange portion 22 can be corrected and the second jig 32 or corresponding to this. Correction can also be achieved by pressing (pressing) the jig to be pressed against the flange portion 22 held by the first jig 31.

  As mentioned above, although the structure and manufacturing process of the shaft member 2 which concern on 1st Embodiment of this invention were demonstrated, of course, it is possible to take a structure and process other than the above, without being limited to this.

  For example, in the first embodiment, a case has been described in which correction related to the posture of the flange portion 22 with respect to the shaft portion 21 is performed after completion of press-fitting of the shaft portion 21, but the shaft portion 21 and the flange in other stages, for example, the press-fitting process. Correction for the portion 22 can also be performed.

FIG. 6 conceptually shows the press-fitting process according to the example. In this example (second embodiment), as shown in FIG. 6A, a first jig 41 that holds the shaft portion 21 and a pressing member 45 that pushes the shaft portion 21 toward the flange portion 22. The third jig 43 is disposed between the two. The jig 43 is provided with an elastic body 44 (including an O-ring and the like, a spring, etc.) between the first jig 41 located below and the third jig 43 is pressed. When a downward load is received from the member 45, this load is transmitted to the first jig 41 via the elastic body 44 . In this case, the elastic body 44 is compressed according to the load, so that the downward displacement of the third jig 43 is absorbed.

The second jig 42 that contacts the lower end surface 22b of the flange portion 22 covers the outer periphery of the flange portion 22 in this example, and the flange portion 22 moves between the first jig 41 during press-fitting. Is to be restrained. In this case, the chamfered portions 21d and 22d provided in the shaft portion 21 and the flange portion 22 function, that is, a gap is provided between the flange portion 22 so as to allow a slight horizontal alignment. (The same applies to the third embodiment). On the cylindrical inner peripheral surface 41a and the lower end surface 41b of the first jig 41 and the upper end surface 42a of the second jig 42 which are in contact with the radial bearing surfaces 21a and 21a and the thrust bearing surfaces (both end surfaces 22a and 22b). Both are finished with high precision. As specific processing accuracy, the same numerical values as in the first embodiment can be cited.

  When the apparatus having the above configuration is used, the shaft portion 21 and the flange portion 22 are fixed as follows.

First, from the state shown in FIG. 6A, the pressing member 45 is lowered by an appropriate drive mechanism. Then, by pressing down the shaft portion 21 in contact with the pressing member 45, press-fitting into the flange portion 22 is started. At this stage (at the start of press-fitting), the opposite press-fitting side end portion of the shaft portion 21 protrudes from the third jig 43 (see FIG. 6A).

After the press-fitting is started in this manner, the pressing member 45 is moved to the third position when the shaft portion 21 is press-fitted by a predetermined length (for example, when the press-fit posture of the shaft portion 21 with respect to the flange portion 22 is stabilized). Is brought into contact with the jig 43 (step shown in FIG. 6B). Then, the downward load is transmitted to the first jig 41 via the elastic body 44 by further lowering the pressing member 45 and pressing the third jig 43 downward. Accordingly, the press-fitting of the shaft portion 21 proceeds while compressing the both end faces 22a, 22b of the flange portion 22 with the first jig 41 and the second jig 42.

In this way, by pressing down the pressing member 45, the shaft portion 21 is press-fitted into the hole 22c of the flange portion 22, and at the same time, a corrective force (here, elastic) is applied to the flange portion 22. The posture of the flange portion 22 relative to the shaft portion 21 is corrected by applying the elastic restoring force of the body 44 . Then, the downward movement of the pressing member 45 is stopped when the press-fitting of the shaft portion 21 into the flange portion 22 is completed. FIG. 6C shows a state in which the pushing of the shaft portion 21 is stopped when the lower end surface 21 c of the shaft portion 21 reaches the same height as the lower end surface 22 b of the flange portion 22. Here, the perpendicularity between the end face 22a, 22b of both the radial bearing surface 21a of the axial part 21 and the flange part 22 of the press-fit goods (shaft member 2) obtained is each corrected to 5 micrometers or less.

  In this way, press-fitting of the shaft portion 21 into the flange portion 22 is started, and when the press-fitting has progressed to some extent, the posture of the flange portion 22 with respect to the shaft portion 21 is corrected, so that deformation or posture caused by the press-fitting is corrected. The press-fitting can be performed while appropriately correcting the distortion. In particular, as in this embodiment, by starting the correction during the press-fitting and performing the press-fitting while gradually increasing the correction force to the flange part 22, the deformation generated in the flange part 22 due to the press-fitting or originally exists. Corrections can be made sequentially with little distortion from the desired posture. Therefore, the load required for correction is small as a whole.

  Further, with this method (configuration), press-fitting and correction can be performed with a single pressing member 45. Therefore, a single drive mechanism (drive system) for applying pressure input and correction force is sufficient, and the equipment cost can be reduced. Moreover, since press-fitting and correction can be carried out with a series of jigs 41 to 45 interlocking with each other, it is also preferable in terms of productivity.

  The method for manufacturing the shaft member 2 for a hydrodynamic bearing device according to the first and second embodiments has been described above. Of course, press-fitting and fixing means other than these can be employed.

  FIG. 7 conceptually shows a method for manufacturing the shaft member 2 according to one example (third embodiment). The press-fitting and fixing device according to the figure includes a first jig 51 and a second jig 52, and a press-fit according to the first embodiment in that it includes a first pressing member 53 and a second pressing member 54. While having the same configuration as the fixing device, the correction start time is different from that of the first embodiment.

That is, as shown in FIG. 7A, the first pressing member 53 is lowered by one drive mechanism from the state where the shaft portion 21 and the flange portion 22 are held by the jigs 51 and 52, and the pressing member 53. The shaft portion 21 in contact with is pushed down. As a result, press-fitting of the shaft portion 21 into the flange portion 22 is started. At this stage (at the start of press-fitting), the opposite press-fitting side end portion of the shaft portion 21 protrudes from the first jig 51 (see FIG. 7A).

  Then, when the press-fitting has progressed to some extent, the second pressing member 54 is lowered using a driving mechanism different from the driving mechanism used for the first pressing member 53 and brought into contact with the first jig 51 ( The state shown in FIG. In this embodiment, the 2nd press member 54 is located in the outer periphery of the 1st press member 53, and it is comprised so that both the press members 53 and 54 can be moved up and down separately independently.

  Then, the second pressing member 54 is further lowered, and the first jig 51 is pressed downward, so that both end faces 22 a and 22 b of the flange portion 22 are compressed between the second jig 52 and the second jig 52. At the same time, the press-fitting of the shaft portion 21 proceeds.

  In this manner, the second pressing member 54 is pushed down independently of the first pressing member 53, so that the shaft portion 21 is press-fitted into the hole 22 c of the flange portion 22 and the flange with respect to the shaft portion 21 is also inserted. The posture of the unit 22 is corrected. Then, when the press-fitting of the shaft portion 21 into the flange portion 22 is completed, the lowering of the first pressing member 53 is stopped.

  Thus, when the press-fitting of the shaft portion 21 to the flange portion 22 is started and the press-fitting has progressed to some extent, the posture of the flange portion 22 with respect to the shaft portion 21 is corrected, so that deformation caused by the press-fit, distortion of the posture, etc. The press-fitting can be performed while appropriately correcting the above. Further, as in this embodiment, if the pressing member (first pressing member 53) and the driving mechanism used for press-fitting, and the pressing member (second pressing member 54) and the driving mechanism used for correction are separately provided, An appropriate load (correcting force) can be applied to the flange portion 22 without being restricted by the pressure input by the first pressing member 53.

  Moreover, although the said embodiment (1st-3rd embodiment) demonstrated the case where the edge part of the axial part 21 of the same dimension as the radial bearing surface 21a was press-fit in the hole 22c of the flange part 22, the axial part 21 was demonstrated. For example, a so-called stepped shaft having a small diameter at the press-fitted portion can be used. In this case, the press-fitting position can be easily grasped and managed by press-fitting to the position where the stepped surface of the shaft part 21 contacts the upper end surface 22 a of the flange part 22.

  In the above embodiment, the case where the end portion of the shaft portion 21 is press-fitted into the hole 22c of the flange portion 22 with a predetermined press-fitting allowance has been described. The invention can be applied. In the case of press-fitting adhesion, the fixing force can be supplemented by an adhesive, so that the press-fitting allowance can be reduced as compared with the case of press-fitting only. Alternatively, since the adhesive also functions as a kind of lubricant at the time of press-fitting, even if the press-fitting allowance is made large, by supplying the adhesive in advance, the frictional force at the time of press-fitting is reduced and small Can be press-fitted with a load. Further, as shown in the drawing, if a chamfered portion 21d is provided at the introduction side end portion of the shaft portion 21, the adhesive supplied in advance to the press-fitted region when the press-fitting is performed with bonding is performed on the lower end surface of the flange portion 22. It is pushed out to the 22b side. Therefore, the chamfered portion 21d provided on the shaft portion 21 can function as a kind of adhesive reservoir.

  In the above embodiment, the flange portion 22 is clamped and pressed by jigs (first jigs 31, 41, 51 and second jigs 32, 42, 52) while holding and restraining the shaft part 21. Thus, the case where the correction force is applied has been described, but the correction force application mode is not limited to this. That is, by applying a correction force to the flange portion 22 other than the above-mentioned jig, or a radial correction force (a force in a direction to reduce the diameter of the flange portion 22 from the outer periphery) alone or in the axial direction. Correction may be achieved by combining and giving. Further, the posture (perpendicularity) can be corrected by applying the correction force to the shaft portion 21, and the correction force can be applied to both the shaft portion 21 and the flange portion 22.

  The press-fitting device used in the above description is merely an example, and any configuration can be adopted as long as the manufacturing method of the shaft member 2 according to the present invention can be embodied.

  Further, the present invention is not limited to the above-described configuration, and can be applied to a hydrodynamic bearing device having another configuration.

  For example, in the above embodiment, the case where the outer peripheral surface of the shaft portion 21 is used as the radial bearing surface 21a and the upper end surface 22a and the lower end surface 22b of the flange portion 22 are used as the thrust bearing surfaces, respectively, is not limited to this. . For example, the present invention can also be applied to a shaft member for a hydrodynamic bearing device that uses only the upper end surface 22a or only the lower end surface 22b as a thrust bearing surface of both end surfaces 22a and 22b.

  FIG. 8 shows a cross-sectional view of a hydrodynamic bearing device 101 according to another configuration example. Features of the hydrodynamic bearing device 101 (main differences from the hydrodynamic bearing device 1 according to FIG. 2) are as follows. That is, in the hydrodynamic bearing device 101, the hub 103 fixed to the upper end (the side opposite to the flange portion 22) of the shaft portion 21 includes a disc portion 103a located on the opening side (upper side) of the housing 107, and the disc portion 103a. It mainly has a cylindrical portion 103b extending downward in the axial direction from the outer peripheral portion. In addition, the upper end surface 107c of the housing 107 is provided with a dynamic pressure groove forming region (for example, the direction of the spiral is reversed) having the arrangement shown in FIG. 4, for example, and a second gap is formed between the lower end surface 103a1 of the opposing disk portions 103a. A thrust bearing gap of the thrust bearing portion T2 is formed.

  On the outer periphery of the housing 107, a tapered sealing surface 107d that gradually increases in diameter upward is formed. The tapered seal surface 107d is an annular seal having a radial dimension gradually reduced from the closed side (downward) to the open side (upward) of the housing 107 between the inner peripheral surface 103b1 of the cylindrical portion 103b. A space S is formed. In FIG. 9, the inner peripheral surface 107a and the fixed surface 107b of the housing 107 correspond to the inner peripheral surface 7a and the fixed surface 7b of the housing 7 in FIG. Since the other configuration conforms to the configuration shown in FIG.

  As described above, even when only the upper end surface 22a of the flange portion 22 is used as the thrust bearing surface, a correction force is applied to one or both of the shaft portion 21 and the flange portion 22 after the press-fitting is completed or in the press-fitting process. By doing so, it is possible to obtain the shaft member 2 having high fixing strength, excellent surface accuracy of the bearing surface, and a high squareness between the radial bearing surface 21a and the thrust bearing surface (upper end surface 22a). it can.

  In each of the above embodiments, the housings 7 and 107 and the bearing sleeve 8 are separated from each other. However, two or more parts selected from a group of parts constituting the fixed side of the fluid dynamic bearing devices 1 and 101 are used. It is also possible to integrate them as far as they can be assembled (integrally formed from the same material, or insert one part and mold the other part). For example, in the configuration shown in FIG. 2, the housing 7 and the bearing sleeve 8, the housing 7 and the lid member 9, and the housing 7 and the seal member 10 can be integrated. It is also possible to integrate the housing 7, the bearing sleeve 8, and the seal member 10. Further, in the configuration shown in FIG. 8, the housing 107 and the bearing sleeve 8 or the housing 107 and the lid member 9 can be integrated.

  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. And a so-called multi-arc bearing in which a wedge-shaped radial gap (bearing gap) is formed between the outer peripheral surface (radial bearing surface 21a) of the opposed shaft portion 21.

  Alternatively, the inner peripheral surface 8a of the bearing sleeve 8 serving as a radial bearing surface is a perfect circular inner peripheral surface not provided with a dynamic pressure groove or arc surface as a dynamic pressure generating portion, and is a perfect circle facing the inner peripheral surface. A so-called perfect circle bearing can be configured with the outer peripheral surface (radial bearing surface 21a).

  One or both of the thrust bearing portions T1 and T2 are also not shown in the figure, but a plurality of radial groove-shaped dynamic pressure grooves are provided at predetermined intervals in the circumferential direction in a region that becomes a thrust bearing surface. It can also be configured by a step bearing or a corrugated bearing (having a corrugated waveform such as an end face).

  Further, in the above embodiment, the case where all the dynamic pressure generating parts are provided on the fixed side (housing 107, bearing sleeve 8, lid member 9, etc.) has been described. 21, flange portion 22, hub 103, etc.). Specifically, the dynamic pressure generating portion described above is provided at one or more of the outer peripheral surface (radial bearing surface 21 a) of the shaft portion 21, both end surfaces 22 a and 22 b of the flange portion 22, and the lower end surface 103 a 1 of the hub 103. It is possible to provide. For example, if the dynamic pressure generating portion illustrated in FIG. 4 is provided on the flange portion 22 side, the lower end surface 31b of the first jig 31 illustrated in FIG. 5 and the upper end surface of the second jig 32 are illustrated. A mold corresponding to the dynamic pressure generating portion is provided in advance in 32 a, and a dynamic pressure generating portion corresponding to the mold is formed on both end faces 22 a and 22 b of the flange portion 22 along with applying a correction force to the flange portion 22. Is also possible.

  Further, in the above embodiment, the lubricating oil is exemplified as the fluid for filling the fluid bearing devices 1 and 101 and forming the fluid film in the radial bearing gap or the thrust bearing gap. For example, a fluid such as air, a fluid lubricant such as a magnetic fluid, or a lubricating grease can be used.

It is sectional drawing of the spindle motor provided with the hydrodynamic bearing apparatus which concerns on 1st Embodiment of this invention. It is sectional drawing of a hydrodynamic bearing apparatus. It is sectional drawing of a bearing sleeve. It is a top view of the end surface facing the flange part of a bearing sleeve. It is a figure which shows notionally the manufacturing method of the shaft member which concerns on 1st Embodiment, (a) is sectional drawing which shows the arrangement | positioning relationship between the shaft part and a flange part before press-fit, (b) is a shaft part at the time of press-fit completion Sectional drawing which shows the arrangement | positioning relationship of a flange part and (c) is sectional drawing which shows the arrangement | positioning relationship of the axial part and flange part in the step which provides the correction force to a flange part after completion of press-fitting. It is a figure which shows notionally the manufacturing method of the shaft member which concerns on 2nd Embodiment, (a) is sectional drawing which shows the arrangement | positioning relationship of the shaft part and flange part before press injection, (b) is the shaft part in the middle of press injection, and Sectional drawing which shows the arrangement | positioning relationship of a flange part, (c) is sectional drawing which shows the arrangement | positioning relationship of the axial part and flange part at the time of press-fit completion. It is a figure which shows notionally the manufacturing method of the shaft member which concerns on 3rd Embodiment, (a) is sectional drawing which shows the arrangement | positioning relationship between the shaft part and a flange part before press injection, (b) is the shaft part in the middle of press injection, and It is sectional drawing which shows the arrangement | positioning relationship of a flange part. It is sectional drawing of the hydrodynamic bearing apparatus which concerns on the other structural example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,101 Fluid bearing apparatus 2 Shaft member 7 for fluid bearing apparatuses 7 Housing 8 Bearing sleeve 21 Shaft part 21a Radial bearing surface 22 Flange part 22c Hole 31,41,51 1st jig | tool 31a, 41a, 51a Cylindrical inner peripheral surface 31b, 41b, 51b Lower end surface 31, 42, 52 Second jig 32a, 42a, 52a Upper end surface 33, 34, 45, 53, 54 Press member 43 Elastic body 44 Third jig R1, R2 Radial bearing portion T1, T2 Thrust bearing part S Seal space

Claims (4)

A shaft portion, and a flange portion that is press-fitted and fixed to one end of the shaft portion. A radial bearing gap is formed between the outer peripheral surface of the shaft portion and a surface facing the outer peripheral surface, and an end surface of the flange portion In the method of manufacturing a shaft member for a hydrodynamic bearing device, a thrust bearing gap is formed between the end face and a surface facing the end face, and the rotary bearing is rotated by a fluid film formed in the radial bearing gap and the thrust bearing gap.
A first jig for holding the shaft portion inserted in the inner peripheral surface; a second jig for holding the flange portion in the thickness direction between the first jig and the shaft; A pressing member that contacts the other end of the portion and pushes the shaft portion toward the flange portion, a third jig disposed between the first jig and the pressing member, and a first jig And when the third jig receives a load from the pressing member toward the flange, the load is transmitted to the first jig with compression. And an elastic body that
Start the press-fitting of the shaft portion against the shaft by the pressing member is brought into contact hole provided in the flange portion by pressing down on the side of the flange portion, at the stage of press-fitting position against the flange portion of the shaft portion is stabilized Then, the pressing member is brought into contact with the third jig and further pressed to advance the press-fitting of the shaft portion into the hole provided in the flange portion, and the flange is formed by the first jig and the second jig. parts by sandwiching compressing method of the fluid bearing device for a shaft member, characterized in that the correction force for correcting the orientation of the flange portion with respect to the shaft portion imparts to the flange portion. A shaft portion, and a flange portion that is press-fitted and fixed to one end of the shaft portion. A radial bearing gap is formed between the outer peripheral surface of the shaft portion and a surface facing the outer peripheral surface, and an end surface of the flange portion In the method of manufacturing a shaft member for a hydrodynamic bearing device, a thrust bearing gap is formed between the end face and a surface facing the end face, and the rotary bearing is rotated by a fluid film formed in the radial bearing gap and the thrust bearing gap.
A first jig for holding the shaft portion inserted in the inner peripheral surface; a second jig for holding the flange portion in the thickness direction between the first jig and the shaft; A first pressing member that abuts against the other end of the first portion and pushes the shaft portion toward the flange portion, abuts against the other end of the first jig, and pushes the first jig toward the negative flange portion. A second pressing member to be inserted,
The first pressing member is brought into contact and the shaft portion is pushed down to the flange portion side to start the press-fitting of the shaft portion into the hole provided in the flange portion, and the press-fit posture of the shaft portion with respect to the flange portion is stabilized. Then, by pressing the second pressing member in contact with the first jig, the press-fitting of the shaft part into the hole provided in the flange part is advanced, and the first jig and the second jig A method of manufacturing a shaft member for a hydrodynamic bearing device, wherein the flange portion is sandwiched and compressed to apply a correction force to the flange portion to correct the posture of the flange portion relative to the shaft portion. The method for manufacturing a shaft member for a hydrodynamic bearing device according to claim 2, wherein the correction force applied to the flange portion is gradually increased as the press-fitting progresses.   A shaft member for a hydrodynamic bearing device manufactured by the method according to claim 1.

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