JP2012184800A - Rotational device and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable more magnetic disk devices to be mounted.SOLUTION: The rotational device 100 includes a hub 10 on which a recording disk is mounted, a shaft 20 having one end side fixed to the hub 10, a first annular surrounding member 80 disposed around the shaft 20 to be fixed to the same, a second annular surrounding member 82 annularly surrounding the shaft 20, and a base 50 to which the second annular surrounding member 82 is fixed. Lubricants 92 lie among the first annular surrounding member 80, the shaft 20, and the second annular surrounding member 82. A radial dynamic pressure generation groove is formed in the inner peripheral surface 84e of the second annular surrounding member 82. An annular recess 104 around the rotational axis R of the hub 10 is formed in the end surface of the second annular surrounding member 82 on the hub 10 side. The first annular surrounding member 80 has a ring part to enter the annular recess 104. Of two gaps where the ring part and the annular recess 104 oppose each other in a radial direction, the gap of the radial-direction outside has an air liquid interface 92a of the lubricants 92.

Description

  The present invention relates to a rotating device and a manufacturing method thereof.

  A hard disk drive is known as a medium used for a storage device of a computer. In a hard disk drive, a magnetic recording disk on which recording tracks are formed is rotated at a high speed by a brushless motor. Conventionally, a disk drive device including a fluid dynamic pressure bearing as described in, for example, Patent Document 1 and Patent Document 2 has been proposed.

JP 2010-96208 A JP 2010-281349 A

  One technique for increasing the capacity of hard disk drives is to install more magnetic recording disks. However, if the total mass of the magnetic recording disk increases, the magnetic recording disk may tilt more greatly when the hard disk drive is subjected to shock or vibration unless special measures are taken. When the inclination becomes large in this way, the data read / write error rate may deteriorate.

  On the other hand, it is conceivable to increase the rigidity of the bearing by increasing the dynamic pressure of the fluid dynamic pressure bearing. However, when this dynamic pressure is increased, the lubricant moves with the rotation of the shaft, and it is possible that the lubricant becomes excessive in one part while the lubricant is deficient in another part. When the lubricant becomes excessive at the gas-liquid interface, it is not preferable because the lubricant easily scatters from the gas-liquid interface. Therefore, increasing the number of magnetic recording disks to be mounted is not so simple.

  The present invention has been made in view of such a situation, and an object thereof is to provide a rotating device capable of mounting more recording disks.

  One embodiment of the present invention relates to a rotating device. The rotating device includes a hub on which a recording disk is to be placed, a shaft having one end fixed to the hub, a first surrounding member that surrounds the shaft and is fixed to the shaft, and a first surrounding member that surrounds the shaft. And a base to which the second surrounding member is fixed. A lubricant is interposed between the first surrounding member and the shaft and the second surrounding member, and a radial dynamic pressure generating groove is formed on either the inner peripheral surface of the second surrounding member or the outer peripheral surface of the shaft. Is done. An annular recess centering on the rotation axis of the hub is formed on the end surface of the second surrounding member on the hub side. The first surrounding member has a ring portion that enters the annular recess. Of the two gaps in which the ring portion and the annular recess are opposed in the radial direction, the gap on the radially outer side has a gas-liquid interface of the lubricant.

  According to this aspect, the gas-liquid interface of the lubricant can be provided on the radially outer side than the surface on which the radial dynamic pressure generating groove is formed.

  Another embodiment of the present invention is also a rotating device. The rotating device includes a hub on which a recording disk is to be placed, a shaft having one end fixed to the hub, a first surrounding member that surrounds the shaft and rotates integrally with the shaft, and surrounds the shaft. A second surrounding member, and a base to which the second surrounding member is fixed. A lubricant is interposed between the first surrounding member and the shaft and the second surrounding member, and a radial dynamic pressure generating groove is formed on either the inner peripheral surface of the second surrounding member or the outer peripheral surface of the shaft. Is done. An annular recess centered on the rotation axis of the hub is formed on either the end surface on the hub side of the base or the end surface on the hub side of the second surrounding member. The first surrounding member has a ring portion that enters the annular recess. Of the two gaps in which the ring portion and the annular recess are opposed in the radial direction, the gap on the radially outer side has a gas-liquid interface of the lubricant.

  Yet another embodiment of the present invention is a method for manufacturing a rotating device. This method is a method of manufacturing the rotary device described above, in which the shaft is inserted into the second surrounding member, the ring portion of the first surrounding member is inserted into the annular recess, and the lubricant is added to the shaft and the second surrounding member. Filling the gap with the two surrounding members, joining the hub to the shaft, and joining the second surrounding member to the base.

  Note that any combination of the above-described constituent elements, and those obtained by replacing the constituent elements and expressions of the present invention with each other among methods, apparatuses, systems, etc. are also effective as an aspect of the present invention.

  According to the present invention, it is possible to provide a rotating device capable of mounting more recording disks.

It is an upper surface figure showing the rotation equipment concerning a 1st embodiment. It is the sectional view on the AA line of FIG. It is a top view of the 3rd surrounding member of FIG. It is an expanded sectional view which expands and shows the gas-liquid interface vicinity of a lubrication agent among the sectional drawings of FIG. It is a schematic diagram which shows the mode of the injection | pouring process in the case of manufacture of the rotary equipment which concerns on 1st Embodiment. It is an expanded sectional view which expands and shows the gas-liquid interface vicinity of the lubricant of the rotation equipment concerning a 2nd embodiment. It is an expanded sectional view which expands and shows the gas-liquid interface vicinity of the lubricant of the rotation equipment concerning a 3rd embodiment.

  In the disk drive device described in Patent Document 1 or Patent Document 2, the radial dynamic pressure groove and the capillary seal portion are provided in series along the shaft. In such a configuration, in order to increase the radial dynamic pressure, it is conceivable to lengthen the portion where the radial dynamic pressure groove is formed in the axial direction. However, if this is done, the entire disk drive device is made thicker or the capillary seal portion is made shorter accordingly. Will do. The former case is not preferable because it goes against the flow of thinning. In the latter case, the amount of lubricant retained is reduced, the sealing function is lowered, and the lubricant is easily scattered.

  The present invention will be described below based on preferred embodiments with reference to the drawings. The same or equivalent components and members shown in the drawings are denoted by the same reference numerals, and repeated descriptions are appropriately omitted. In addition, the dimensions of the members in each drawing are appropriately enlarged or reduced for easy understanding. Also, in the drawings, some of the members that are not important for describing the embodiment are omitted.

  The rotating device according to the embodiment is suitably used as a disk drive device, particularly a hard disk drive on which a magnetic recording disk is mounted. In this rotating device, a capillary seal having a gas-liquid interface of a lubricant is provided on the radially outer side of the outer peripheral surface of a shaft that rotates with respect to the base. Furthermore, the hub on which the magnetic recording disk is mounted does not contact the lubricant. Accordingly, since the capillary seal and the gap where the radial dynamic pressure is generated can be lengthened almost independently of each other in the direction of the rotation axis, the capillary seal can be lengthened and the leakage of the lubricant can be reduced while increasing the rigidity of the bearing.

  In the case of injecting lubricant during the manufacturing process, it is usually necessary to prepare a work space capable of reducing pressure and returning pressure. In the manufacturing process of the rotating device according to the embodiment, since it is not necessary to attach a hub to the subassembly at the time of injecting the lubricant, the injecting operation can be performed even in a small work space. Accordingly, a rotating device that is easier to manufacture is provided. The “subassembly” is an object to be processed in a manufacturing process of a rotating device, for example.

(First embodiment)
FIG. 1 is a top view showing a rotating device 100 according to the first embodiment. In FIG. 1, a state in which the top cover is removed is shown to show the configuration inside the rotating device 100. The rotating device 100 includes a base 50, a hub 10, a magnetic recording disk 200, a data read / write unit 8, and a top cover.
Hereinafter, the side on which the hub 10 is mounted with respect to the base 50 will be described as the upper side.

  The magnetic recording disk 200 is placed on the hub 10 and rotates as the hub 10 rotates. The base 50 is formed by die casting an aluminum alloy. The base 50 rotatably supports the hub 10 via a bearing unit described later. The data read / write unit 8 includes a recording / reproducing head 8a, a swing arm 8b, a pivot assembly 8c, and a voice coil motor 8d. The recording / reproducing head 8a is attached to the tip of the swing arm 8b, records data on the magnetic recording disk 200, and reads data from the magnetic recording disk 200. The pivot assembly 8c supports the swing arm 8b with respect to the base 50 so as to be swingable around the head rotation axis. The voice coil motor 8 d swings the swing arm 8 b around the head rotation axis, and moves the recording / reproducing head 8 a to a desired position on the recording surface of the magnetic recording disk 200. The data read / write unit 8 is configured using a known technique for controlling the position of the head.

  2 is a cross-sectional view taken along line AA in FIG. The rotating device 100 is equipped with four 3.5-inch magnetic recording disks 200 having a diameter of 95 (mm) and rotates them. The diameter of each central hole of the assumed four magnetic recording disks 200 is 25 (mm) and the thickness is 1.27 (mm).

  The rotating device 100 includes a substantially cup-shaped hub 10, a shaft 20, a flange 22, a yoke 30, a cylindrical magnet 40, a base 50, a laminated core 60, a coil 70, and a first surrounding member 80. A second surrounding member 82, a counter plate 90, and a lubricant 92.

  The hub 10 is formed in a convex shape with the rotation axis R as the center. Hereinafter, a case where four magnetic recording disks 200 are mounted on the hub 10 will be considered. The central hole of the four magnetic recording disks 200 is fitted into the cylindrical outer cylindrical surface 10b of the hub 10 protruding upward. Of the four magnetic recording disks 200, the lowermost magnetic recording disk is seated on a seating surface 10c of the surface of the hub 10 that protrudes radially from the lower end of the outer cylindrical surface 10b. The diameter of the outer cylindrical surface 10b is 25 (mm), and the length in the direction of the rotation axis R is 12.3 (mm). This length is such that four or more magnetic recording disks having the thickness of 1.27 (mm) can be attached.

  When the four magnetic recording disks 200 are referred to as the first, second, third, and fourth magnetic recording disks from the top, respectively, the annular first spacer 202, second spacer 204, and third spacer 206 are Inserted between the first and second magnetic recording disks, between the second and third magnetic recording disks, and between the third and fourth magnetic recording disks, respectively. The clamper 208 presses the first magnetic recording disk downward. As a result, the four magnetic recording disks 200, the first spacer 202, the second spacer 204, and the third spacer 206 as a whole are pressed against and fixed to the seating surface 10c of the hub 10. The clamper 208 is fixed to the upper surface 10 a of the hub 10 by four clamp screws 210.

  The yoke 30 has an inverted L-shaped cross section and is formed of a magnetic material such as iron. The yoke 30 is fixed to the inner peripheral surface 10d of the hub 10 that is in contact with the back side of the outer cylindrical surface 10b by using both adhesion and press fitting.

  A cylindrical magnet 40 is bonded and fixed to the inner peripheral surface 30 a of the yoke 30. The cylindrical magnet 40 is made of a rare earth material such as neodymium, iron, or boron, and faces the 12 salient poles of the laminated core 60 in the radial direction (that is, the direction orthogonal to the rotation axis R). The cylindrical magnet 40 is magnetized for driving with 16 poles along the circumferential direction (that is, the tangential direction of a circle centering on the rotation axis R).

  The hub 10 is provided with a center hole 10e centered on the rotation axis R. One end of the shaft 20 is fixed to the center hole 10e by using both press fitting and adhesion. A flange 22 is press-fitted into the other end of the shaft 20. The flange 22 is fixed to the shaft 20 so as to surround the other end side of the shaft 20.

  The base 50 is provided with a through hole 50b that passes through the base 50 with the rotation axis R as the center. The base 50 has a protrusion 52 that protrudes upward from the edge of the through hole 50b. The inner peripheral surface of the protrusion 52 and the peripheral surface of the through hole 50b are substantially continuous.

  The laminated core 60 has an annular portion and 12 salient poles extending outward in the radial direction therefrom. The inner peripheral surface 60a of the annular portion is fixed to the outer peripheral surface 52b of the protruding portion 52 by adhesion, press fitting, or the like. The laminated core 60 is formed by laminating 17 thin electromagnetic steel plates and integrating them by caulking. An insulating coating such as electrodeposition coating or powder coating is applied to the surface of the laminated core 60. A coil 70 is wound around each salient pole. When a three-phase substantially sinusoidal drive current flows through the coil 70, a magnetic flux is generated along the salient poles.

  The second surrounding member 82 surrounds the shaft 20, is inserted into the through hole 50 b of the base 50, and is bonded and fixed there. On the hub 10 side of the second surrounding member 82, an annular recess 104 is formed with the rotation axis R recessed downward in the rotation axis R direction. The second surrounding member 82 is formed with a communication hole 102 that communicates the upper side and the lower side thereof.

  The second surrounding member 82 includes a cylindrical third surrounding member 84 that surrounds the shaft 20, and a cylindrical fourth surrounding member 86 that surrounds the third surrounding member 84. The third surrounding member 84 and the fourth surrounding member 86 are formed as separate bodies. The outer peripheral surface 86b of the fourth surrounding member 86 is at least partially opposed to the peripheral surface of the through hole 50b via an adhesive. The recess 104 is formed between the third surrounding member 84 and the fourth surrounding member 86.

  The third surrounding member 84 and the fourth surrounding member 86 can be formed from various metal materials and resin materials. The third surrounding member 84 and the fourth surrounding member 86 may be formed of the same or different materials. For example, at least one of the third surrounding member 84 and the fourth surrounding member 86 may be manufactured by cutting a metal material such as brass and performing electroless nickel plating. In this case, processing becomes easy and high processing accuracy can be secured. For example, at least one of the third surrounding member 84 and the fourth surrounding member 86 may be manufactured from a stainless material such as SUS303. In this case, high processing accuracy can be ensured. The third surrounding member 84 and the fourth surrounding member 862 may be formed of a material having an equal linear expansion coefficient. In this case, even when the temperature becomes high or low, a gap is hardly generated between the third surrounding member 84 and the fourth surrounding member 86, and the usable temperature range can be widened.

  The first surrounding member 80 surrounds the shaft 20 and is fixed to the shaft 20, and rotates together with the shaft 20 when the rotating device 100 rotates. The cross section of the first surrounding member 80 has a substantially inverted L shape. A part of the first surrounding member 80 enters the recess 104.

  The counter plate 90 is fixed to the lower surface 86f of the fourth surrounding member 86 by adhesion so as to close the end of the second surrounding member 82 on the base 50 side. The upper surface of the counter plate 90, the lower surface 84d of the third surrounding member 84, and the inner peripheral surface 86a of the fourth surrounding member 86 form a flange space 106 in which the flange 22 is accommodated.

  In the gap between the shaft 20, the flange 22 and the first surrounding member 80 which are a part of the rotating body, and the third surrounding member 84, the fourth surrounding member 86 and the counter plate 90 which are a part of the fixed body. Is filled with a lubricant 92. The communication hole 102 is also filled with the lubricant 92. The gas-liquid interface 92a of the lubricant 92 exists in a gap where the portion of the first surrounding member 80 that has entered the recess 104 and the fourth surrounding member 86 face each other in the radial direction.

  The inner peripheral surface 84e of the third surrounding member 84 includes a first radial dynamic pressure generating surface 108 and a second radial dynamic pressure generating surface 110 that are spaced apart from each other in the vertical direction. The first radial dynamic pressure generating surface 108 and the second radial dynamic pressure generating surface 110 are respectively formed with herringbone-shaped radial dynamic pressure generating grooves. Hereinafter, the first radial dynamic pressure generation surface 108 is a lower (base 50 side) radial dynamic pressure generation surface, and the second radial dynamic pressure generation surface 110 is an upper (hub 10 side) radial dynamic pressure generation surface.

  Herringbone-shaped thrust dynamic pressure generating grooves are formed on the upper surface 22a and the lower surface 22b of the flange 22, respectively. When the rotating device 100 rotates, the rotating body is supported in the radial direction and the rotation axis R direction by the dynamic pressure generated in the lubricant 92 by the radial dynamic pressure generating groove and the thrust dynamic pressure generating groove. The first surrounding member 80, the second surrounding member 82, the shaft 20, the flange 22, the counter plate 90, and the lubricant 92 constitute a bearing unit that is attached to the base 50 and rotatably supports the hub 10.

  A radial dynamic pressure generating groove may be formed on the outer peripheral surface 20 a of the shaft 20. Further, the thrust dynamic pressure is applied to the lower surface 84d of the third surrounding member 84 facing the upper surface 22a of the flange 22 in the rotation axis R direction, the upper surface of the counter plate 90 facing the lower surface 22b of the flange 22 in the rotation axis R direction, or both. A generation groove may be formed.

  FIG. 3 is a top view of the third surrounding member 84. The AA line in FIG. 3 corresponds to the AA line in FIG. The 3rd surrounding member 84 has the upper surface 84a which is an end surface at the side of the hub 10, and the outer peripheral surface 84b formed so that it might become substantially cylindrical shape. A communication groove 84c, which is a recess that penetrates the third surrounding member 84 in the rotation axis R direction, is linearly formed along the rotation axis R direction on the outer peripheral surface 84b. Therefore, in the state where the third surrounding member 84 is attached to the fourth surrounding member 86, the communication hole 102 is formed by the communication groove 84 c and the inner peripheral surface 86 a of the fourth surrounding member 86.

  The communication hole may be formed by providing a communication groove on the inner peripheral surface 86 a of the fourth surrounding member 86 instead of the outer peripheral surface 84 b of the third surrounding member 84.

  4 is an enlarged cross-sectional view showing the vicinity of the gas-liquid interface 92a of the lubricant 92 in the cross-sectional view of FIG. The end surface, that is, the upper surface of the fourth surrounding member 86 on the hub 10 side is an inner upper surface 86c, an inclined surface 86d that is radially outward of the inner upper surface 86c and adjacent to the inner upper surface 86c, and an inclined surface that is radially outward of the inclined surface 86d. 86d and an outer upper surface 86e adjacent thereto. The inclined surface 86d expands upward with an inclination angle θ with respect to the rotation axis R. The inner upper surface 86c and the outer upper surface 86e are annular surfaces substantially orthogonal to the rotation axis R, respectively. The outer upper surface 86e is located above the inner upper surface 86c, that is, close to the hub 10.

  The upper surface 84 a of the third surrounding member 84 is located above the inner upper surface 86 c of the fourth surrounding member 86, that is, close to the hub 10. Therefore, the recess 104 is formed by the outer peripheral surface 84b of the third surrounding member 84, the inner upper surface 86c of the fourth surrounding member 86, and the inclined surface 86d.

The first surrounding member 80 includes a ring portion 80 a that enters the recess 104 and surrounds at least the upper end of the third surrounding member 84, and a disk portion 80 b. An inner peripheral surface 80c of the disk portion 80b is in contact with the shaft 20. Ring portion 80a is coupled to the outer peripheral side of disk portion 80b.
The disk part 80b hits the stepped part 20b provided on the outer peripheral surface 20a of the shaft 20 in the direction of the rotation axis R. The upper surface 80d of the disk portion 80b is in contact with the hub 10. Therefore, the first surrounding member 80 is sandwiched and fixed between the hub 10 and the stepped portion 20 b of the shaft 20. In this case, the accuracy of the mounting position of the first surrounding member 80 with respect to the shaft 20 can be ensured, and displacement of the first surrounding member 80 with respect to the shaft 20 is suppressed.

  When the ring portion 80a enters the concave portion 104, the concave portion 104 includes an outer gap 112 in which the ring portion 80a and the fourth surrounding member 86 are opposed to each other in the radial direction, and the ring portion 80a and the third surrounding member 84. Are formed in the inner gap 114 facing each other in the radial direction. The outer gap 112 is located radially outside the inner gap 114. The outer gap 112 has a gas-liquid interface 92 a of the lubricant 92. Since the outer gap 112 gradually expands upward, it functions as a capillary seal, and leakage of the lubricant 92 is suppressed by capillary action. In the relationship with the second radial dynamic pressure generation surface 110, the outer gap 112 and the second radial dynamic pressure generation surface 110 at least partially overlap in the direction of the rotation axis R. That is, when defining the coordinate axis in the direction of the rotation axis R, there is a common part between the coordinate range of the outer gap 112 and the coordinate range of the second radial dynamic pressure generating surface 110.

  In the present embodiment, the ring part 80a and the disk part 80b of the first surrounding member 80 are integrally formed. The first surrounding member 80 can be formed from various metal materials and plastic materials. For example, when it is formed by cutting from a stainless material corresponding to SUS303, high processing accuracy can be obtained because processing is relatively easy. The ring part 80a and the disk part 80b may be formed separately.

  The lubricant 92 includes an outer gap 112, an inner gap 114, a radial gap 116 between the third surrounding member 84 and the shaft 20, a first thrust gap 118 between the flange 22 and the third surrounding member 84, the flange 22 and the counter plate. 90 and the second thrust gap 120 in succession. In addition to the radial gap 116, the communication hole 102 communicates the outer gap 112 and the inner gap 114 with the base side of the first radial dynamic pressure generating surface 108. In particular, the communication hole 102 communicates a portion of the inner gap 114 on the outer gap 112 side and the first thrust gap 118.

  Returning to FIG. 2, the lower end of the communication hole 102 is provided at a position along the outer edge of the first thrust gap 118. In the first thrust gap 118, the flange 22 rotates on the inner side of the outer edge thereof, so that the communication hole 102 has a lower end in a portion of the first thrust gap 118 that avoids the thrust dynamic pressure generating groove.

  Between the portion corresponding to the first radial dynamic pressure generating surface 108 and the portion corresponding to the second radial dynamic pressure generating surface 110 in the radial gap 116, the gap with the shaft 20 is larger than the gap in those portions. A lubricant reservoir 122 is provided.

  The operation of the rotating device 100 configured as described above will be described. In order to rotate the magnetic recording disk 200, a three-phase drive current is supplied to the coil 70. When the drive current flows through the coil 70, magnetic flux is generated along the 12 salient poles. Torque is applied to the cylindrical magnet 40 by this magnetic flux, and the rotating body and the magnetic recording disk 200 fitted thereto rotate. At the same time, the voice coil motor 8d swings the swing arm 8b, so that the recording / reproducing head 8a moves back and forth on the magnetic recording disk 200. The recording / reproducing head 8a converts magnetic data recorded on the magnetic recording disk 200 into an electric signal and transmits it to a control board (not shown), and transmits data sent from the control board in the form of an electric signal to the magnetic recording disk 200. Write as magnetic data on top.

  According to the rotating device 100 according to the present embodiment, the gas-liquid interface 92 a of the lubricant 92 exists in the outer gap 112. Therefore, the capillary seal and the radial gap 116 where the radial dynamic pressure is generated are allowed to overlap in the direction of the rotation axis R. Thereby, the distance in the rotation axis R direction between the first radial dynamic pressure generating surface 108 and the second radial dynamic pressure generating surface 110, that is, the bearing span, can be expanded without being so limited by the length of the capillary seal, Thereby, the radial rigidity of the bearing can be increased.

  Conversely, the length of the capillary seal can be increased without being constrained by the bearing span so that a sufficient amount of the lubricant 92 can be held and scattering can be suppressed. Further, when the amount of the lubricant 92 to be held can be reduced, the outer gap 112 can be narrowed accordingly, and the capillary force can be increased to reduce the leakage of the lubricant 92 when receiving an impact, for example. .

As described above, since the scattering of the lubricant can be sufficiently suppressed in the capillary seal, the length (that is, the area) of the first radial dynamic pressure generating surface 108 and the second radial dynamic pressure generating surface 110 itself in the rotation axis R direction is increased. Thus, even if the radial dynamic pressure is increased, the possibility of lubricant scattering due to a dynamic pressure imbalance that can occur can be kept low. Accordingly, it is possible to further increase the radial dynamic pressure and suppress the rigidity while suppressing the scattering of the lubricant.
It should be noted that the improvement in rigidity by strengthening the radial dynamic pressure can generally be accompanied by an increase in power consumption due to the bearing loss, but such a loss does not accompany the improvement in rigidity due to the expansion of the bearing span.

  In particular, in a situation where the thickness is determined by the thickness standard of the rotating device or the thickness cannot be increased due to the demand for thinning, according to the rotating device 100 according to the present embodiment, both the bearing span and the length of the capillary seal are substantially equal to each other. Independently, the length of the rotating device 100 can be set to the maximum length.

  Therefore, a low error rate can be maintained by increasing the rigidity of the bearing while it is thin with more, for example, four or more magnetic recording disks mounted, and at the same time it can be used for a relatively long time by providing a deep capillary seal. However, a rotating device capable of maintaining a sufficient amount of the lubricant 92 is provided.

  Further, since the lubricant 92 exists in both the outer gap 112 and the inner gap 114, the amount of the lubricant 92 retained is increased as compared with the case where the lubricant 92 exists only in the inner gap, that is, the gas-liquid interface exists in the inner gap. Can do.

It is also conceivable to use the lower surface of the hub in order to provide the gas-liquid interface of the lubricant radially outward. That is, it is conceivable that the lubricant path is folded back in contact with the lower surface of the hub. However, this is not preferable because the lubricant is injected into the subassembly to which the hub is attached in the manufacturing process. The reason is, for example,
(1) The subassembly includes a hub and is large.
(2) In general, the position where the tip of the nozzle that discharges the lubricant is to be applied is in the back of the subassembly, so that the relative positioning of the nozzle and the subassembly before discharging the lubricant becomes more complicated, and the time Take,
(3) It becomes difficult to check the height of the liquid level after injection.
(4) Opportunities for the hub to become dirty or scratched with oil, etc.
It is.

  The increase in work time associated with (2) may not be so great for a single rotating device, but it has a non-negligible impact on the productivity of factories where tens of thousands or hundreds of thousands of rotating devices are manufactured. Can be affected.

  On the other hand, in the rotating device 100 according to the present embodiment, the lubricant 92 does not contact the hub 10. FIG. 5 is a schematic diagram showing a state of an injection process when manufacturing the rotating device 100 according to the present embodiment. The sub-assembly 250 as a target for injecting the lubricant is in a state before the hub 10 is coupled, and the shaft 20, the flange 22, the first surrounding member 80, the third surrounding member 84, and the fourth An encircling member 86 and a counter plate 90 are included. In the step of injecting the lubricant, first, the subassembly 250 is placed in the work space, and the work space is decompressed. Next, the discharge nozzle 252 is inserted into the outer gap 112 from above, and a necessary amount of lubricant is injected from the discharge nozzle 252. Then, the work space is restored.

  In this case, since the subassembly 250 does not include the hub 10, the working space can be further reduced, and a small-sized decompression device may be prepared. In general, the injection process is required to be performed in a cleaner environment than the subsequent processes in order to prevent foreign matters from being mixed into the lubricant. The larger such a clean environment, the higher the cost required to create and maintain that environment. Therefore, according to the rotating device 100 according to the present embodiment, the working space in the injection process can be further reduced, and thus the cost for generating and maintaining a clean environment can be reduced.

Furthermore, according to the rotating device 100 according to the present embodiment, since the outer gap 112 can be easily accessed without being blocked by the hub 10, the discharge nozzle 252 can be positioned more quickly and accurately. Furthermore, after the lubricant is injected, the gas-liquid interface of the lubricant can be accessed without being blocked by the hub 10, so that the level of the liquid surface can be more easily inspected.
Further, since the lubricant is injected before the hub 10 is mounted on the subassembly 250, the hub is not soiled or damaged by the injection of the lubricant.

  Further, in the rotating device 100 according to the present embodiment, both ends of the radial gap 116 are communicated with each other through communication holes 102 provided separately from the radial gap 116. Therefore, the pressure of the lubricant 92 at both ends of the radial gap 116 can be averaged to prevent an excessive pressure difference from occurring. As a result, the radial dynamic pressure during rotation can be increased without being restricted by the occurrence of a pressure difference, and the rigidity of the bearing can be increased. Therefore, this configuration is particularly suitable for a rotating device on which a large number of magnetic recording disks are to be mounted. is there.

  In addition, in the rotating device 100 according to the present embodiment, since the occurrence of a pressure difference during rotation can be suppressed, the occurrence of a phenomenon in which the lubricant 92 is easily collected and scattered in the outer gap 112 and the inner gap 114 is suppressed. .

  In the rotating device 100 according to the present embodiment, the communication hole 102 has a lower end in a portion of the first thrust gap 118 that avoids the thrust dynamic pressure generating groove. Therefore, even when the communication hole 102 is provided, the disturbance of the distribution of thrust dynamic pressure generated by the thrust dynamic pressure generating groove when the rotating device 100 is rotated can be reduced.

  The disk portion 80b is fixed to the shaft 20 by an interference fit or a gap fit. In the embodiment of FIG. 3, an interference fit is employed. In this case, since the disk portion 80b is relatively strongly fixed to the shaft 20, it is difficult to come off in the state of the subassembly 250 without the hub 10, for example.

  Moreover, in the rotating device 100 according to the present embodiment, the recess 104 and the communication hole 102 are formed by a third surrounding member 84 and a fourth surrounding member 86 that are formed separately from each other. Therefore, compared with the case where a recessed part and a communicating hole are formed from one member, they can be formed more easily and with high precision. For example, the inner upper surface 86 c and the inclined surface 86 d of the recess 104 can be formed by a lathe or the like as the inner peripheral side surface of the fourth surrounding member 86. This processing is easier than, for example, a case where an annular groove is formed on the end surface of one cylindrical member using a milling machine, and the processing accuracy is high. In particular, since the inclined surface 86d can be formed with high accuracy, variations in the volume and performance of the capillary seal can be reduced. In addition, when the communication hole is formed by drilling, the diameter of the communication hole to be formed is generally smaller than its length, so it may take time to check whether the middle of the communication hole is clogged. . On the other hand, in the rotating device 100 according to the present embodiment, the communication hole 102 is formed by the communication groove 84 c on the outer peripheral surface 84 b of the third surrounding member 84. Therefore, it is possible to more easily inspect whether or not the communication groove 84c is formed as intended.

(Size)
The dimensions of the rotating device 100 according to the present embodiment may be set as follows.
(1) The length of the joint between the hub 10 and the shaft 20, that is, the length L1 of the center hole 10e in the direction of the rotation axis R is determined by the width W1 of the first radial dynamic pressure generating surface 108 in the direction of the rotation axis R It is larger than any of the widths W2 of the pressure generating surface 110 in the direction of the rotation axis R. In this case, since the joining length L1 between the hub 10 and the shaft 20 can be further increased, the contact area between the hub 10 and the shaft 20 can be increased and the joining strength can be increased. As a result, even if a large number of magnetic recording disks are mounted, the inclination of the magnetic recording disk when subjected to an impact or vibration can be sufficiently suppressed.

  Specifically, the joining length L1 of the hub 10 and the shaft 20 is 5.66 mm, the width W1 of the first radial dynamic pressure generating surface 108 is 1.6 mm, and the width W2 of the second radial dynamic pressure generating surface 110 is It may be 4.4 mm. The joining length L1 may be at least three times the width W1 of the first radial dynamic pressure generating surface 108 and at least the width W2 of the second radial dynamic pressure generating surface 110. Moreover, the diameter of the part corresponding to the radial dynamic pressure generating surfaces 108 and 110 of the shaft 20 is 4.5 mm to 5 mm, and the gap between the part and the radial dynamic pressure generating surfaces 108 and 110 is 3 μm to 5 μm. Also good. According to the simulation conducted by the present inventor, it is confirmed that a radial dynamic pressure having a practically sufficient size can be obtained when the width W1 of the first radial dynamic pressure generating surface 108 is in the range of 1.4 mm to 2 mm. It was done. Further, according to the same simulation, the rotating device 100 on which the four magnetic recording disks 200 were mounted was subjected to impact and vibration when the length L1 of the joint between the hub 10 and the shaft 20 was in the range of 5 mm to 7 mm. It was confirmed that the tilt of the magnetic recording disk can be sufficiently suppressed.

  (2) The length of the capillary seal, that is, the height L2 of the outer upper surface 86e viewed from the inner upper surface 86c may be set to satisfy W1 <L2 <W2. For example, the height L2 may be set to 2 mm.

  (3) According to a simulation performed by the present inventor, when an impact or vibration is applied to the hub 10, the first radial dynamic pressure generating surface 108 is located near the second radial dynamic pressure generating surface 110 on the side close to the hub 10. It was confirmed that a load in the radial direction more than twice the vicinity was applied. In the rotating device 100 according to the present embodiment, the width W2 of the second radial dynamic pressure generation surface 110 may be larger than a value obtained by doubling the width W1 of the first radial dynamic pressure generation surface. In this case, the load in the radial direction can be supported in a balanced manner, and the tilt of the magnetic recording disk can be effectively suppressed.

  (4) The thickness T1 of the flange 22 is directly connected to the length of the joint portion between the flange 22 and the shaft 20, and it is desirable to increase the thickness T1 from the viewpoint of maintaining the strength of the joint. According to the simulation conducted by the present inventor, if the diameter of the joint surface between the flange 22 and the shaft 20 is 4.5 mm to 5 mm and the thickness T1 of the flange 22 is 1.8 mm or more, four magnetic recording disks Even when 200 was mounted, it was confirmed that the connection between the flange 22 and the shaft 20 can be sufficiently maintained when subjected to a predetermined impact. Corresponding to this simulation result, in the rotating device 100 according to the present embodiment, the thickness T1 of the flange 22 may be set to 2 mm so as to be larger than the width W1 of the first radial dynamic pressure generating surface.

(Production method)
A method for manufacturing the rotating device 100 according to the present embodiment will be described. The third surrounding member 84 is inserted into the fourth surrounding member 86 to form the second surrounding member 82. The shaft 20 to which the flange 22 is attached is loosely inserted into the second surrounding member 82 from below. The first surrounding member 80 is fitted from the upper side of the shaft 20 until it hits the stepped portion 20b, and the ring portion 80a of the first surrounding member 80 is caused to enter the recess 104 of the second surrounding member 82. A counter plate 90 is attached to the second surrounding member 82 to form a subassembly 250 as shown in FIG.

The injection of lubricant into the subassembly 250 is as described in connection with FIG.
After the injection of the lubricant, the position of the gas-liquid interface 92a of the lubricant 92 in the outer gap 112 in the direction of the rotation axis R is measured. For example, the position of the gas-liquid interface 92a can be measured by irradiating the gas-liquid interface 92a with laser and detecting the reflected light. By repairing or eliminating subassemblies whose measured positions are not within a predetermined reference height range, products that do not meet the reference can be removed.

  The hub 10 is coupled to the shaft 20. For example, an adhesive is circumferentially applied to the lower side of the peripheral surface of the center hole 10e of the hub 10, and the shaft 10 protruding from the sub-assembly that is supported upright is covered with the hub 10 and coupled. . An interference fit may be used in combination with this connection. In this case, the strength of the coupling between the hub 10 and the shaft 20 can be increased.

  After the hub 10 is attached to the shaft 20, the subassembly is bonded and fixed to the through hole 50 b of the base 50 with the hub 10 kept in a desired posture with respect to the base 50. For example, an adhesive is applied circumferentially on the upper surface of the through hole 50b of the base 50, and the subassembly is inserted. Then, the adhesive is temporarily cured in a state where a force is applied to the hub 10 so that the outer cylindrical surface 10 b of the hub 10 does not tilt with respect to the base 50. In this case, the inclination of the outer cylindrical surface 10b of the hub 10 with respect to the base 50 is suppressed.

Thereafter, the temporarily cured adhesive is fully cured. For example, the target may be left in a high temperature bath of 80 to 100 degrees for 60 to 180 minutes. In this case, volatile components from the cured adhesive can be reduced.
Thereafter, the rotary device 100 is manufactured by incorporating other members and performing a predetermined inspection.

(Second Embodiment)
FIG. 6 is an enlarged cross-sectional view showing the vicinity of the gas-liquid interface 392a of the lubricant 392 of the rotating device 300 according to the second embodiment. FIG. 6 corresponds to FIG. The first surrounding member 380 surrounds the shaft 20 and is fixed to the shaft 20, and rotates together with the shaft 20 when the rotating device 300 rotates. The first surrounding member 380 has a ring part 380a and a disk part 380b.

  The second surrounding member 382 surrounds the shaft 20, is inserted into the through hole 50 b of the base 50, and is bonded and fixed there. On the hub 10 side of the second surrounding member 382, an annular recess 304 is formed with the rotation axis R recessed downward in the rotation axis R direction. The second surrounding member 382 includes a third surrounding member 384 that surrounds the shaft 20 and a fourth surrounding member 386 that surrounds the third surrounding member 384. The fourth surrounding member 386 is formed separately from the fifth surrounding member 306 surrounding the third surrounding member 384 and the fifth surrounding member 306, and the sixth surrounding member surrounds the ring portion 380a. Surrounding member 308. The sixth surrounding member 308 is fixed to the upper surface of the fifth surrounding member 306 by adhesion or the like.

  The recess 304 is formed by the third surrounding member 384, the fifth surrounding member 306, and the sixth surrounding member 308. In this case, the process for forming the recess 304 for each member forming the recess 304 becomes simpler.

  The rotating device 300 according to the second embodiment does not have the flange 22. Instead, a thrust dynamic pressure generating groove is formed on either the upper surface 384a of the third surrounding member 384 or the lower surface 380d of the disk portion 380b facing the third surrounding member 384 in the direction of the rotation axis R.

  Also, the ring portion 380a and the recess 304 are configured to limit movement in a direction away from the base 50 of the hub 10. In particular, the locking structure 302 is formed by the ring portion 380 a and the fourth surrounding member 386. The locking structure 302 functions to prevent the rotating body from coming off instead of the flange 22. The lower end portion of the ring portion 380a is a protruding portion 380c that protrudes outward in the radial direction. The fourth surrounding member 386 has a retaining recess 386a that is recessed in the radial direction corresponding to the shape of the projecting portion 380c. When the rotating body moves upward with respect to the fixed body, that is, rises, the upper part of the overhanging part 380c comes into contact with the upper part of the retaining recess 386a when it floats a predetermined maximum distance, and further rising is restricted.

  According to the rotating device 300 according to the present embodiment, the same effects as the effects achieved by the rotating device 100 according to the first embodiment are exhibited.

(Third embodiment)
FIG. 7 is an enlarged cross-sectional view showing the vicinity of the gas-liquid interface 492a of the lubricant 492 of the rotating device 400 according to the third embodiment. FIG. 7 corresponds to FIG. The first surrounding member 480 surrounds the upper end side of the shaft 20 and is fixed to the shaft 20, and rotates integrally with the shaft 20 when the rotating device 400 rotates. The first surrounding member 480 includes a ring portion 80 a and an insertion portion 480 b inserted between the shaft 20 and the hub 410. An inner peripheral surface 480 c of the insertion part 480 b is in contact with the shaft 20, and an outer peripheral surface 480 d is in contact with the hub 410. Ring portion 80a is coupled to the outer peripheral side of insertion portion 480b.

  The insertion part 480b hits the stepped part 20b provided on the outer peripheral surface 20a of the shaft 20 in the direction of the rotation axis R. In this case, the accuracy of the mounting position of the first surrounding member 480 with respect to the shaft 20 can be ensured, and displacement of the first surrounding member 480 with respect to the shaft 20 is suppressed. A similar step-butting structure may be applied to the attachment of the hub 410 to the first surrounding member 480.

  According to the rotating device 400 according to the present embodiment, the same operational effects as the operational effects exhibited by the rotating device 100 according to the first embodiment are exhibited.

  The configuration and operation of the rotating device according to the embodiment and the manufacturing method thereof have been described above. It is to be understood by those skilled in the art that these embodiments are exemplifications, and that various modifications can be made to combinations of the respective components, and such modifications are within the scope of the present invention. Also, combinations of the embodiments are possible.

  In the first to third embodiments, the rotating device is equipped with four 3.5-inch magnetic recording disks 200 having a diameter of 95 (mm), and the diameter of the central hole of each magnetic recording disk is 25. (Mm) and thickness of 1.27 (mm) have been described, but the present invention is not limited to this. For example, a rotating device is equipped with four 2.5-inch magnetic recording disks having a diameter of 63 (mm). May be. The diameter of the central hole of this magnetic recording disk is 20 (mm) and the thickness is 0.6 (mm) or 0.8 (mm).

  In the first to third embodiments, the so-called outer rotor type rotating device in which the cylindrical magnet is located outside the laminated core has been described. However, the present invention is not limited to this. For example, a so-called inner rotor type rotating device in which a cylindrical magnet is positioned inside a laminated core may be used.

  In the first to third embodiments, the case where the bearing unit is directly attached to the base has been described. However, the present invention is not limited to this. For example, a brushless motor having the same configuration as that of any of the rotating devices according to the first to third embodiments may be separately formed, and then the brushless motor may be attached to the chassis.

  In the first to third embodiments, the case where a laminated core is used has been described, but the core may not be a laminated core.

  In the first to third embodiments, the case where the herringbone-shaped groove is used to generate the radial dynamic pressure and the thrust dynamic pressure has been described. However, the present invention is not limited to this. For example, a spiral groove may be used, or a combination of these may be used. The shape of such a groove can be appropriately selected so as to exhibit desired characteristics.

  10 Hub, 20 Shaft, 22 Flange, 30 Yoke, 40 Cylindrical magnet, 50 Base, 60 Laminated core, 70 Coil, 80 First surrounding member, 82 Second surrounding member, 90 Counter plate, 92 Lubricant, 100 Rotating equipment, 102 communication hole, 104 recess.

Claims (11)

A hub on which the recording disk should be placed;
A shaft having one end fixed to the hub;
A first surrounding member surrounding the shaft and fixed to the shaft;
A second surrounding member surrounding the shaft;
A base on which the second surrounding member is fixed,
A lubricant is interposed between the first surrounding member and the shaft and the second surrounding member, and a radial motion is generated on either the inner peripheral surface of the second surrounding member or the outer peripheral surface of the shaft. A pressure generating groove is formed,
An annular recess centered on the rotation axis of the hub is formed on the end surface of the second surrounding member on the hub side,
The first surrounding member has a ring portion that enters the annular recess,
A rotating device characterized in that a gap on the radially outer side of two gaps in which the ring portion and the annular recess are opposed in the radial direction has a gas-liquid interface of the lubricant.   2. The rotating device according to claim 1, wherein the first surrounding member has a disk portion whose inner peripheral surface is in contact with the shaft and to which the ring portion is coupled on the outer peripheral side.   The rotating device according to claim 2, wherein the outer peripheral surface of the shaft has a stepped portion with which the disk portion abuts in the axial direction.   In addition to the clearance between the shaft and the second surrounding member, a communication path that connects the clearance between the ring portion and the annular recess and the base side of the radial dynamic pressure generating groove is the second surrounding. The rotating device according to claim 1, wherein the rotating device is provided on a member. The second surrounding member is
A third surrounding member surrounding the shaft;
A fourth surrounding member formed separately from the third surrounding member and surrounding the third surrounding member;
5. The rotating device according to claim 1, wherein the annular recess is formed between the third surrounding member and the fourth surrounding member. The fourth surrounding member is
A fifth surrounding member surrounding the third surrounding member;
A sixth surrounding member formed separately from the fifth surrounding member and surrounding the ring portion;
The rotary device according to claim 5, wherein the annular recess is formed by the fifth surrounding member, the sixth surrounding member, and the third surrounding member. A flange that is fixed to the shaft so as to surround the other end of the shaft;
The rotating device according to any one of claims 1 to 6, wherein a thrust dynamic pressure generating groove is formed in any one of surfaces in which the flange and the second surrounding member oppose each other in the axial direction.   The thrust dynamic pressure generating groove is formed in any one of the surfaces where the first surrounding member and the second surrounding member face each other in the axial direction. Rotating equipment.   The rotating device according to any one of claims 1 to 8, wherein the ring portion and the annular recess are configured to limit movement of the hub in a direction away from the base. A hub on which the recording disk should be placed;
A shaft having one end fixed to the hub;
A first surrounding member that surrounds the shaft and rotates integrally with the shaft;
A second surrounding member surrounding the shaft;
A base on which the second surrounding member is fixed,
A lubricant is interposed between the first surrounding member and the shaft and the second surrounding member, and a radial motion is generated on either the inner peripheral surface of the second surrounding member or the outer peripheral surface of the shaft. A pressure generating groove is formed,
An annular recess is formed around the rotation axis of the hub on either the end surface on the hub side of the base or the end surface on the hub side of the second surrounding member,
The first surrounding member has a ring portion that enters the annular recess,
A rotating device characterized in that a gap on the radially outer side of two gaps in which the ring portion and the annular recess are opposed in the radial direction has a gas-liquid interface of the lubricant. A method for manufacturing a rotating device according to any one of claims 1 to 10,
Inserting the shaft into the second surrounding member and allowing the ring portion of the first surrounding member to enter the annular recess;
Filling the lubricant in the gap between the shaft and the second surrounding member;
Coupling the hub to the shaft;
Coupling the second surrounding member to the base. A method of manufacturing a rotating device.

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