JP2005127525A - Hydrodynamic bearing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydrodynamic bearing device to be assembled in a spindle motor, having improved rotating accuracy. <P>SOLUTION: The hydrodynamic bearing device 1 comprises a shaft member 2 having a flange portion 2b at one end of a shaft portion 2a, radial bearing portions R1, R2 for supporting the shaft portion 2a in non-contact therewith in the radial direction with the hydrodynamic operation of fluid caused in a gap between the radial bearing portions, and a thrust bearing portion for supporting the flange portion 2b in non-contact therewith in the thrusting direction with the hydrodynamic operation of the fluid caused in the gap between the thrust bearing portions. The shaft portion 2a has an outer peripheral face region facing the gap between the radial bearing portions and an outer peripheral face region in which a disc hub for a disc device is mounted. The outer peripheral face region facing the gap between the radial bearing portions and the outer peripheral face region in which the disc hub is mounted are ground at the same time at a circularity of 0.5μm or less. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention is incorporated in a spindle motor such as a magnetic disk device such as HDD or FDD, an optical disk device such as CD-ROM, CD-R / RW, or DVD-ROM / RAM, or a magneto-optical disk device such as MD or MO. The present invention relates to a hydrodynamic bearing device.

  As is well known, the various motors listed above have been promoted to increase speed, reduce costs, reduce noise, etc. in addition to high rotational accuracy. As one of the factors that determine the required performance, a bearing that supports the spindle of the motor has been regarded as important. In recent years, as a bearing of this type, a hydrodynamic bearing having characteristics excellent in the required performance has been considered. The use is being studied or put into practical use.

  For example, in a hydrodynamic bearing device incorporated in a spindle motor of a disk device such as an HDD, a radial bearing that rotatably supports a shaft member in a radial direction and a non-contact support that rotatably supports a shaft member in a thrust direction. A thrust bearing portion is provided. As these bearing portions, a dynamic pressure type bearing having a dynamic pressure generating groove (dynamic pressure groove) on the bearing surface is used.

  In this case, the dynamic pressure groove of the radial bearing portion is formed on the inner peripheral surface of the housing or the bearing member or the outer peripheral surface of the shaft member, and the dynamic pressure groove of the thrust bearing portion uses a shaft member having a flange portion. It is formed on both end surfaces of the flange portion or on the opposite surfaces (end surface of the bearing member, bottom surface of the housing, etc.).

  Further, in recent years, this type of spindle motor is required to have higher rotational accuracy in order to increase the information recording density and increase the rotational speed. To meet this demand, a dynamic pressure type incorporated in the spindle motor is required. Higher rotational accuracy is also required for bearings.

  By the way, in order to increase the rotation accuracy of the dynamic pressure type bearing, it is important to manage the clearance in the radial bearing gap and the thrust bearing gap in which the dynamic pressure is generated. In order to optimize this clearance management, it is necessary to accurately process the components of the hydrodynamic bearing involved in each bearing clearance, particularly the shaft member that forms each bearing clearance with the bearing member. Therefore, at the time of processing or manufacturing of the shaft member, a required grinding process is applied as a finishing process to a portion where each bearing gap of the shaft member is formed.

  More specifically, as shown in FIG. 10, the shaft member 2 is formed by integrally forming a flange portion 2b at one end of the shaft portion 2a, and a bearing member (not shown) is disposed on the outer peripheral side thereof. Then, a radial bearing gap is formed between the outer peripheral surface of the shaft portion 2a and the bearing member, and between the front end surface (end surface on the shaft portion 2a side) 2b1 of the flange portion 2b and the bearing member, and the base of the flange portion 2b. Thrust bearing gaps are respectively formed between the end surface (end surface on the opposite shaft portion 2a side) 2b2 and the inner bottom surface (not shown) of the housing.

  In this case, in the manufacturing process of the shaft member 2, the outer peripheral surface of the shaft portion 2a that forms a radial bearing gap with the bearing member is ground. However, this outer peripheral surface is conventionally ground. The following method is adopted as an example.

  That is, as shown in FIG. 11, a pair of center holes 2bc are formed in the center of the tip end surface 2a4 of the shaft portion 2a and the base end surface 2b2 of the flange portion in the shaft member 2, respectively, and the tips are reduced in diameter. The centering member 41 is fitted into the center holes 2bc, and the shaft member 2 is sandwiched and supported by the centering members 41.

  Under such a state, grinding is performed by pressing the grindstone 43 against the outer peripheral surface of the shaft member 2 while applying rotation around the shaft center from the centering member 41 to the shaft member 2.

  However, in this center-supported grinding process, if the center position is out of order, the shaft member swings around during rotation, resulting in the shaft member outer peripheral surface being ground in an inclined manner or There is also a possibility that the roundness or the coaxiality is deviated, and the rotational accuracy of the hydrodynamic bearing device is lowered.

  This invention is made | formed in view of the said situation, and makes it a technical subject to aim at the improvement of the rotation precision of a hydrodynamic bearing apparatus.

  In order to solve the above technical problem, the present invention provides a shaft member having a flange portion at one end of the shaft portion, and a radial bearing portion that supports the shaft portion in a radial direction in a radial direction by a dynamic pressure action of fluid generated in the radial bearing gap. And a thrust bearing portion that supports the flange portion in the thrust direction in a non-contact manner by the dynamic pressure action of fluid generated in the thrust bearing gap, the shaft portion of the shaft member has an outer peripheral surface facing the radial bearing gap And an outer peripheral surface region to which the disk hub of the disk device is mounted, and the outer peripheral surface region facing the radial bearing gap and the outer peripheral surface region to which the disk hub is mounted are simultaneously ground, and the roundness is increased. A configuration of 0.5 μm or less is provided.

  In the shaft portion of the shaft member, the outer peripheral surface region facing the radial bearing gap and the outer peripheral surface region to which the disk hub is mounted are ground simultaneously, so that the coaxiality of both outer peripheral surface regions is increased. In addition, the roundness of both outer peripheral surface regions is regulated to 0.5 μm or less. Therefore, the dynamic pressure bearing device of the present invention can rotatably support the disc hub with high rotational accuracy when incorporated in the spindle motor of the disc device.

  The shaft member in the hydrodynamic bearing device of the present invention is, for example, a support member that supports the shaft outer peripheral surface of the shaft member while rotating the shaft member around the shaft center by supporting the shaft member in a plane contact at both axial ends by a pair of plate members. It can manufacture by grinding this outer peripheral surface with a grindstone, supporting by.

  Here, “planar contact support of the shaft member at both axial ends by a pair of plate members” means that the base end surface of the flange portion of the shaft member (the end surface on the side opposite to the shaft portion of the flange portion) is connected to one plate member, for example, A flat plate is supported by the backing plate, and the tip surface of the shaft portion of the shaft member is supported by a flat surface by the other plate member, for example, a pressure plate, and the shaft member is sandwiched between the two plate members with an appropriate clamping force. Means that.

  According to such a configuration, since both end surfaces of the shaft member are supported in plane contact by the pair of plate members, the contact area between each end surface and each plate member as compared with the case of the conventional center support. Becomes wider, and slippage hardly occurs between each end face and each plate member, and a favorable contact state is obtained in order to obtain a large clamping force. Therefore, the peripheral speed when the shaft member rotates around the shaft center can be sufficiently increased, thereby improving the grinding efficiency and the work efficiency. Moreover, since both ends of the shaft member in the axial direction are not center-supported as in the prior art but are supported in a plane contact, the shaft member is less likely to sway during rotation, and the shaft outer peripheral surface is of high quality. This is advantageous for grinding. In addition, if the support member that supports the outer peripheral surface of the shaft member is disposed at the substantially central portion in the axial direction of the shaft member, a grinding process that presses the grindstone over the entire axial length of the outer peripheral surface of the shaft member. The number of support members is not particularly limited, but one or two support members are arranged at positions facing the grindstone (positions where the pressing force from the grindstone can be received). It is preferable to install.

  In this case, at least the plate member that is in plane contact with the flange portion of the shaft member (specifically, the end surface on the side opposite to the shaft portion of the flange portion) may have a relief portion in a predetermined region of the rotation center portion of the contact surface. Is preferred. That is, when cutting the end face of the shaft member prior to grinding, the peripheral speed of the outer peripheral portion of the end face is relatively high when the shaft member is rotated, and therefore appropriate cutting is performed with a cutting tool. However, since the peripheral speed of the rotation center portion of the end face is relatively low, sufficient cutting cannot be performed. For this reason, the situation where a convex part exists in the rotation center part vicinity in the end surface (especially end surface of a flange part) of the shaft member which finished the cutting process is caused. Therefore, as described above, if a relief portion is formed in a predetermined region of the rotation center portion of the contact surface of the plate member that is in flat contact with the end surface of the flange portion, the convex portion formed on the end surface during cutting is formed. Contact with the plate member can be avoided, and an appropriate plane contact state can be ensured.

  In addition, it is preferable that the outer diameter d of the contact surface of the plate member that is in flat contact with the flange portion is set smaller than the outer diameter D of the flange portion. In this way, compared to the case where the contact surface of the plate member is about the same diameter as the flange diameter, the contact surface slips due to the increased clamping pressure acting per unit area of the contact surface. It becomes difficult to occur, and the difference from the support state of the end surface on the shaft portion side is reduced, so that the shaft member can be supported at both ends stably in a balanced manner.

  In the above configuration, the contact portion of the plate member with the flange portion is preferably elastically supported by the elastic member. In this case, it is preferable that the contact portion of the plate member with the flange portion is composed of, for example, a metal plate having high rigidity. In this way, the elastic member is appropriately elastically deformed, so that the contact portion of the plate member can be brought into flat contact with no gap over the entire contact portion of the flange portion, and is in a state of planar contact support with respect to the flange portion. Therefore, the outer peripheral surface of the shaft portion can be ground with high accuracy.

  Moreover, it is preferable that the supporting member is supporting the axial part outer peripheral surface of a shaft member over the range of 2/3 or more of the axial center direction. In this way, the pressing force from the grindstone can be uniformly supported by the support member over a wide range in the axial direction, and the outer periphery of the shaft member can be accurately reproduced without causing rattling or vibration in the shaft portion of the shaft member. It becomes possible to grind the surface.

  In this case, as described above, in addition to the step of grinding the outer peripheral surface of the shaft member, when including the step of grinding the end surface on the shaft portion side and the end surface on the opposite shaft portion side of the flange portion, It is preferable that the end surface on the shaft side is ground before the end surface on the shaft portion side is ground. In this way, the end surface of the flange portion on the side opposite to the shaft portion is first ground to finish the end surface with high accuracy, and then the end surface on the shaft portion side of the flange portion is supported while the finished end surface is supported by the support member. Therefore, both end surfaces of the flange portion on the opposite shaft side and the shaft portion side can be ground with high accuracy. On the other hand, if the end surface on the shaft side of the flange portion is ground first, this end surface does not participate in the grinding of the end surface on the opposite shaft portion side of the flange portion. The end face on the shaft part side of the flange part finished with precision cannot be used effectively. Therefore, as described above, if the end surface of the flange portion on the side opposite to the shaft portion is ground first, this end surface can be used effectively, and the grinding processing sequence becomes appropriate.

  According to the present invention, it is possible to provide a hydrodynamic bearing device capable of rotating and supporting a disk hub with high rotational accuracy when incorporated in a spindle motor of the disk device.

  Hereinafter, embodiments of the present invention will be described. 1 to 6 are schematic views showing an implementation state of a grinding process in a shaft member of a hydrodynamic bearing device according to the present invention, and FIG. 8 is an enlarged longitudinal front view showing an internal structure of the hydrodynamic bearing device.

  For the convenience of explanation, the dynamic pressure type bearing device will be described in detail before explaining the implementation status of the grinding step in the manufacturing method.

  As shown in FIG. 8, the hydrodynamic bearing device 1 includes a bottomed cylindrical housing 7 having an opening 7a at one end, a cylindrical bearing sleeve 8 fixed to the inner periphery of the housing 7, The main component is the shaft member 2 disposed on the inner periphery of the bearing sleeve 8 and the seal member 10 fixed to the opening 7a of the housing 7.

  The housing 7 is made of, for example, a soft metal material such as brass, and includes a cylindrical side portion 7b and a bottom portion 7c. A spiral-shaped dynamic pressure groove is formed. In this embodiment, the housing 7 has a side part 7b and a bottom part 7c separated from each other, and a lid-like member to be the bottom part 7c is fastened to the other end opening of the side part 7b and fixed by means such as adhesion. However, the side portion 7b and the bottom portion 7c may be integrated.

  The shaft member 2 is formed of a metal material such as stainless steel, for example, and includes a shaft portion 2a and a flange portion 2b provided integrally or separately at the lower end of the shaft portion 2a, and an outer peripheral surface of the shaft portion 2a. Further, a relief groove 2a1 and a tapered surface 2a2 are formed. The tapered surface 2a2 has a predetermined taper angle that gradually decreases toward the upper side, and a cylindrical surface 2a3 is continuously formed immediately above the tapered surface 2a2.

  The bearing member 8 is made of, for example, a porous body, particularly a sintered metal containing copper as a main component, and the internal pores are impregnated with lubricating oil to form an oil-impregnated bearing. The inner peripheral surface 8a of the bearing member 8 is formed with two upper and lower radial bearing surfaces R1 and R2, and these radial bearing surfaces R1 and R2 are separated in the axial direction with a spacing R3 interposed therebetween. The bearing surfaces R1 and R2 are also provided with herringbone-shaped dynamic pressure grooves not shown in the drawing. Further, the spacing portion R3 is set so as to face the thin groove 2a1 of the shaft portion 2a, and the gap between them is set to be larger than the radial bearing gap. In addition, a spiral-shaped dynamic pressure groove (not shown), for example, is also formed in the region that becomes the thrust bearing surface of the bottom surface 8c of the bearing member 8.

  The seal member 10 is formed in an annular shape, and is fixed to the inner peripheral surface of the opening 7a of the housing 7 by means such as press-fitting and / or adhesion. In this embodiment, the seal member 10 The inner peripheral surface 10 a is formed in a cylindrical shape, and the lower end surface 10 b of the seal member 10 is in contact with the upper end surface 8 b of the bearing member 8. The inner peripheral surface 10a of the seal member 10 is opposed to the tapered surface 2a2 of the shaft portion 2a via a predetermined gap, and a tapered shape that gradually expands upward from the housing 7 is provided between the opposed surfaces. A seal space S is formed.

  Next, a manufacturing method of the above-described dynamic pressure type bearing device 1, specifically, an implementation status of the grinding process of the shaft member 2 that is a component of the dynamic pressure type bearing device 1 will be described.

  As shown in FIG. 1, the base end surface (end surface on the side opposite to the shaft 2a) 2b2 of the flange portion 2b of the shaft member 2 is a front end surface (hereinafter referred to as a first front end surface) of the backing plate 11 which is one plate member. The tip surface 2a4 of the shaft portion 2a of the shaft member 2 is in planar contact with the tip surface (hereinafter referred to as the second tip surface) 12a of the pressure plate 12 which is the other plate member. In this case, the backing plate 11 is a cylindrical body, the first tip surface 11a is formed as a plane having a circular outline, and the pressure plate 12 is also a cylindrical body, The second tip surface 12a is formed as a flat surface having a circular contour.

  During grinding, the shaft member 2 rotates around the axis Z as indicated by the arrow A together with the plates 11 and 12 with the shaft member 2 being sandwiched between the backing plate 11 and the pressure plate 12. To do. In this case, a rotational driving force around the axis Z is applied to the shaft member 2 from the backing plate 11 and / or the pressure plate 12, and a clamping force (pressing force) along the axis Z direction from the pressure plate 12 is applied. Is granted.

  Under such a state, the outer periphery of the shaft portion 2a of the shaft member 2, more specifically, the outer periphery of the large-diameter non-tapered portion 2ax formed adjacent to the thin groove 2a1 at the substantially central portion in the axial direction of the shaft portion 2a. The surface is supported by a support member (shoe) 13, and a grindstone 14 having a grinding surface shape extending substantially along the axial length of the shaft portion 2a from the opposite side across the axis Z of the support member 13 is formed on the shaft portion 2a. It is pressed over substantially the entire outer peripheral surface.

  As a result, the shaft member 2 is rotated at a sufficient peripheral speed (for example, about 1500 rpm), and the outer peripheral surface of the shaft portion 2a is supported by the support member 13, so that the shaft member 2 does not cause unfair swinging. The outer peripheral surface is ground with high efficiency by the grindstone 14.

  In this case, as shown in FIG. 2, the outer diameter d of the first distal end surface 11a of the backing plate 11 is smaller than the outer diameter D of the base end surface 2b2 of the flange portion 2b of the shaft member 2. A circular relief portion (concave portion) 11b is formed in a predetermined region of the rotation center portion of the first tip surface 11a.

  Therefore, at the time of cutting of the shaft member 2 prior to this grinding, the central portion of the base end surface 2b2 as shown in FIG. 3 is caused by the low peripheral speed of the rotation center portion of the base end surface 2b2 of the flange portion 2b. Even if the convex portion 2bx is formed, the convex portion 2bx is accommodated in the internal space of the escape portion 11b, so the base end surface 2b2 of the flange portion 2b and the first front end surface of the backing plate 11 Appropriate planar contact with 11a can be ensured. Note that an escape portion may be formed on the second tip surface 12a of the pressure plate 12 in the same manner as described above.

  FIG. 4 is a schematic view showing a grinding state when the support member 13 and the backing plate 11 of the grinding apparatus used for carrying out the grinding step are different from the above. In the figure, the same components as those shown in FIGS. 1 to 3 are denoted by the same reference numerals, and detailed description thereof will be omitted below.

  As shown in FIG. 4, the support member 13 has a length parallel to the axial center Z of 2/3 or more, for example, about 3/4, with respect to the axial length of the shaft portion 2a of the shaft member 2. Accordingly, the support member 13 is in contact with the outer peripheral surface of the shaft portion 2a over a range of 2/3 or more in the axial direction. In this case, the contact state of the support member 13 with respect to the outer peripheral surface of the shaft portion 2a does not necessarily require that the entire tip end of the support member 13 is in contact with the outer peripheral surface of the shaft portion 2a as shown in the figure. It may be in contact at multiple locations. However, in this case, the contact range from the contact portion at one end of the support member 13 to the contact portion at the other end is required to be 2/3 or more in the axial direction of the outer peripheral surface of the shaft portion 2a.

  Further, as shown in the figure, the backing plate 11 has a metal plate 11x, which is a contact portion that makes a flat contact with the base end surface 2b2 of the flange portion 2b, and a backing plate 11 via an elastic member 11y made of rubber, resin, or the like. 11 is elastically supported at the base. Accordingly, when the elastic member 11y is appropriately elastically deformed, the plate 11x can always be kept in close contact with the base end surface 2b2 of the flange portion 2b, and a stable planar contact support state can be obtained.

  FIG. 7 shows the roundness (μm) of the outer peripheral surface of the shaft portion 2a after grinding with respect to the flatness (μm) of the base end surface 2b2 of the flange portion 2b. It is a graph which shows the result compared with what was by the grinding process in the condition shown in FIG. In this test, the test workpiece (shaft member 2) is made of stainless steel (HV580), the total length is 18 mm, the shaft diameter is 4.5 mm, the flange diameter is 7 mm, and the flange thickness is 1.5 mm. And an alumina-based grindstone was used as the grindstone. In this graph, the characteristic line indicated by x and symbol A1 is the result of the grinding situation shown in FIG. 1, and the characteristic line indicated by ○ and symbol A2 is the result of the grinding situation shown in FIG. is there. In this case, “flatness” means a difference in height between the most protruding part and the most depressed part on the measurement surface. Further, “roundness” means the magnitude of deviation from the geometric perfect circle of the outer peripheral surface of the shaft portion 2a.

  According to this graph, as shown in FIG. 4, an elastic member 11y is attached to the backing plate 11, and the outer peripheral surface of the shaft portion 2a is supported by the support member 13 at 2/3 or more in the axial direction. Since it becomes difficult to be affected by the flatness of the base end surface 2b2 of 2b and almost no radial backlash (vibration) occurs, it can be understood that the outer peripheral surface of the shaft portion 2a is ground with high accuracy. Specifically, in this method, if the flatness of the base end surface 2b2 of the flange portion 2b is 3 μm or less, the roundness of the shaft portion 2a can be at least 0.5 μm or less. On the other hand, as shown in FIG. 1, if the elastic member is not provided and the outer peripheral surface of the shaft portion 2a is supported by the support member 13 at 1/5 or less of the axial direction, the base end surface 2b2 of the flange portion 2b. When the flatness is 2.5 μm or more, the roundness of the outer peripheral surface of the shaft portion 2a is about 1 μm or more. In this case, in order to obtain highly accurate roundness, the flatness of the base end surface 2b2 of the flange portion 2b needs to be 1.0 μm or less.

  On the other hand, grinding of the distal end surface (end surface on the shaft portion 2a side) 2b1 and the base end surface 2b2 of the flange portion 2b in the shaft member 2 is performed as follows.

  First, as shown in FIG. 5, the tip surface 2a4 of the shaft portion 2a of the shaft member 2 is supported by the tip support plate 15, and the shaft is linked to a rotating roll (not shown) contacting the outer peripheral surface of the shaft portion 2a. The member 2 is rotated. Then, while supporting the outer peripheral surface of the shaft portion 2a, more specifically, the outer peripheral surfaces of the large-diameter non-tapered portions 2ax and 2ax formed adjacent to both sides of the thinning groove 2a1, the support member (shoe) 16 supports the flange. Grinding is performed by pressing the grindstone 17 against the base end face 2b2 of the portion 2b.

  After the grinding of the base end surface 2b2 of the flange portion 2b in this way, the base end surface 2b2 of the flange portion 2b in the shaft member 2 is supported by the base end support plate 18 as shown in FIG. Similarly, the shaft member 2 is rotated in conjunction with a rotating roll (not shown) contacting the outer peripheral surface of the shaft portion 2a. Then, grinding is performed by pressing the grindstone 20 against the tip end surface 2b1 of the flange portion 2b while supporting the outer peripheral surface of the shaft portion 2a with a support member (shoe) 19 in the same manner as described above.

  After performing the above-described processes, the finishing process for the shaft member 2 is performed, and after assembling together with other components, predetermined processes such as an oiling process and a wiping process are performed, and thus, FIG. A finished product of the hydrodynamic bearing device 1 described based on the above is obtained. The hydrodynamic bearing device 1 as a finished product is used as one component of the motor as described below.

  That is, the spindle motor 30 for information equipment illustrated in FIG. 9 is used for a disk drive device such as an HDD, and the disk hub 31 mounted on the shaft member 2 of the dynamic pressure type bearing device 1 described above, for example, a radius A motor stator 32 and a motor rotor 33 are provided to face each other with a gap in the direction. The stator 32 is attached to the outer periphery of the casing 34, and the rotor 33 is attached to the inner periphery of the disk hub 31. The housing 7 of the hydrodynamic bearing device 1 is mounted on the inner periphery of the casing 34. The disk hub 31 holds one or more disks D1 such as magnetic disks. When the stator 32 is energized, the rotor 33 is rotated by the exciting force between the stator 32 and the rotor 33, whereby the disk hub 31 and the shaft member 2 are rotated together.

It is a schematic front view which shows one implementation condition of the manufacturing method of the dynamic pressure type bearing device which concerns on embodiment of this invention. It is a components arrangement | sequence perspective view which shows the 1st implementation condition of the manufacturing method of the dynamic pressure type bearing device which concerns on embodiment of this invention. It is a principal part enlarged front view which shows the 1st implementation condition of the manufacturing method of the dynamic pressure type bearing device which concerns on embodiment of this invention. It is a schematic front view which shows the 2nd implementation condition of the manufacturing method of the dynamic pressure type bearing device which concerns on embodiment of this invention. It is a schematic front view which shows the 3rd implementation condition of the manufacturing method of the dynamic pressure type bearing device which concerns on embodiment of this invention. It is a schematic front view which shows the 4th implementation condition of the manufacturing method of the dynamic pressure type bearing device which concerns on embodiment of this invention. It is a graph which shows the precision of the shaft member manufactured by the manufacturing method concerning the embodiment of the present invention. It is a vertical front view which shows the dynamic pressure type bearing apparatus manufactured by the manufacturing method which concerns on embodiment of this invention. It is a schematic longitudinal cross-sectional front view which shows the state in which the dynamic pressure type bearing apparatus manufactured by the manufacturing method which concerns on embodiment of this invention was integrated in the spindle motor. It is a front view which shows the single-piece | unit of the shaft member manufactured by the manufacturing method which concerns on embodiment of this invention. It is a schematic front view which shows one implementation of the manufacturing method of the conventional dynamic pressure type bearing apparatus.

Explanation of symbols

1 Hydrodynamic bearing device 2 Shaft member
2a Shaft
2b Flange
2b1 Flange end surface (end surface on the shaft side of the flange)
2b2 Base end surface of the flange (end surface on the opposite side of the flange)
7 Housing
11 Backing plate (plate member)
11a First tip surface (contact surface)
11b Relief
11y elastic member
12 Pressure plate (plate member)
13 Support member (shoe)
14 Whetstone

Claims (1)

A shaft member having a flange portion at one end of the shaft portion, a radial bearing portion that supports the shaft portion in a non-contact manner in the radial direction by a fluid dynamic pressure effect generated in the radial bearing clearance, and a fluid dynamic pressure effect generated in the thrust bearing clearance In the hydrodynamic bearing device comprising a thrust bearing portion that supports the flange portion in the thrust direction in a non-contact manner,
The shaft portion of the shaft member has an outer peripheral surface region facing the radial bearing gap and an outer peripheral surface region to which a disk hub of a disk device is mounted, and the outer peripheral surface region facing the radial bearing gap and the disc A hydrodynamic bearing device, wherein the outer peripheral surface region to which the hub is mounted is simultaneously ground and the roundness is 0.5 μm or less.

Images