JP4108696B2 - Disk unit and pressing clamp - Google Patents

Description

  The present invention relates to a recording disk device such as a magnetic disk device used as an external storage device of a computer system.

  For example, in a magnetic disk device such as a hard disk drive (HDD), a magnetic disk is mounted on a rotating shaft driven by a spindle motor. When recording or reproducing information, the magnetic disk is driven to rotate with respect to the magnetic head.

  The magnetic disk is sandwiched between a flange formed on the rotating shaft and a pressing clamp fixed to the tip of the rotating shaft, and is firmly fixed to the rotating shaft.

  The flat plate main body of the pressing clamp is fixed to the tip of the rotating shaft by screws arranged on one virtual circle around the center of the rotating shaft. Therefore, in the flat plate body of the clamp, a strong pressing force is exhibited in the screw hole region through which the screw passes, and the pressing force is weakened in an intermediate region between the screw holes along the virtual circle.

  The strength of the pressing force along the virtual circle increases the amount of sinking of the screw hole region as compared with the amount of sinking of the intermediate region between the screw holes, and causes the plate body to swell along the virtual circle. The waviness of the flat plate main body is transferred to the magnetic disk with which the outer peripheral portion of the flat plate main body contacts, and the magnetic disk is swung. The waviness of the magnetic disk adversely affects the writing and reading of information by the magnetic head. In particular, in recent magnetic disk devices in which the flying height of the magnetic head is suppressed, it is becoming difficult to avoid interference between the magnetic head and the magnetic disk due to such waviness.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a recording disk device that can suppress deformation of a pressing clamp as much as possible and eliminate waviness of the recording disk. Another object of the present invention is to provide a pressing clamp capable of realizing such a recording disk device.

  In order to achieve the above object, according to the first invention, a rotary shaft having a flange, a recording disc mounted on the rotary shaft, a pressing clamp for sandwiching the recording disc between the flange, and the center of the rotary shaft Compared with the screw that is arranged around one virtual circle around and fixes the flat plate body of the pressing clamp to the tip of the rotating shaft and the screw hole region of the flat plate body, the flat plate is in the middle region along the virtual circle between the screw hole regions There is provided a recording disk device comprising a stiffness suppressing mechanism that relatively reduces the stiffness of the main body.

  In such a recording disk device, when the pressing clamp is fixed to the tip of the rotary shaft with a screw, a relatively strong tightening force acts on the screw hole region of the pressing clamp. At this time, since the rigidity of the flat plate body is relatively weakened in the intermediate region, a tightening force equivalent to that of the screw hole region is also transmitted to the intermediate region, and the sinking amounts of both regions become substantially equal. As a result, the deformation of the pressing clamp is suppressed, and the undulation of the recording disk with which the pressing clamp contacts is eliminated.

  The rigidity suppressing mechanism may include an annular wall rising from the surface of the flat plate main body, and a notch formed on the top surface of the annular wall in the intermediate region. The rigidity of the entire flat plate body is increased by the action of the annular wall, while the rigidity of the intermediate region is relatively weakened by the action of the notches. As a result, the deformation of the pressing clamp is suppressed as described above.

  The notch may include a tapered surface that continues to the top surface. Since the top surface and the notch are connected by a tapered surface, it is possible to employ pressing for forming the pressing clamp. In the case of employing press working, for example, a metal material such as aluminum or stainless steel may be used. In selecting the metal material, it is desirable to consider the strength and rigidity of the molded pressing clamp and the thermal expansion coefficient.

  The notch may be formed by a curved surface. For example, if the joint between the bottom surface of the notch and the tapered surface or the joint between the top surface of the annular wall and the tapered surface is formed as a curved surface, it is possible to avoid stress concentration at the joint. As a result, it is avoided that the tightening force of the screw that fixes the pressing clamp to the rotating shaft is weakened.

  The rigidity suppressing mechanism may include an annular wall that rises from the surface of the flat plate body, and a notch that is formed on the outer peripheral surface of the annular wall in the intermediate region. The rigidity of the entire flat plate body is increased by the action of the annular wall, while the rigidity of the intermediate region is relatively weakened by the action of the notches. As a result, the deformation of the pressing clamp is suppressed as described above. Moreover, since the continuity of the inner peripheral surface of the annular wall is maintained, even when the balancer is arranged in the space inside the annular wall, the balancer will not accidentally fall down from the pressing clamp.

  Furthermore, the rigidity suppressing mechanism may include a through hole formed in the flat plate body in the intermediate region. According to such a through hole, the rigidity of the intermediate region is relatively weakened, and as a result, the deformation of the pressing clamp is suppressed as described above.

  The through hole may include a large hole located between the screw holes and a small hole having a smaller diameter than the large hole and disposed between the large hole and the screw hole. By changing the hole diameter, the rigidity of the flat plate main body can be changed along the circumferential direction, and as a result, the deformation of the pressing clamp can be finely adjusted.

  Further, according to the second invention, the rotary shaft having the flange, the recording disc attached to the rotary shaft, the pressing clamp for sandwiching the recording disc between the flange, and one imaginary circle around the center of the rotary shaft A recording disk device comprising: a screw arranged to be fixed along the flat plate main body of the pressing clamp to the tip of the rotary shaft; and an annular wall that rises from an outer edge of the flat plate main body and is formed thicker than the flat plate main body. Provided.

  According to this configuration, the rigidity of the outer edge of the flat plate body in contact with the recording disk is increased, while the rigidity of the screw hole region of the flat plate body is relatively weakened. As a result, even if the fastening force of the screw acts, the deformation of the flat plate body is absorbed around the screw hole, and the deformation is suppressed at the outer edge of the flat plate body on which the annular wall is formed. Therefore, the disk surface of the recording disk is flattened.

  The pressing clamp may be provided by being incorporated in the recording disk device as described above, or may be provided as a single clamp.

  As described above, according to the present invention, the deformation of the pressing clamp can be suppressed as much as possible, and as a result, the waviness of the recording disk can be reduced.

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

  FIG. 1 shows a hard disk drive (HDD) as a specific example of a recording disk device. The housing 11 of the HDD 10 is largely divided into a box-shaped housing body 12 and a cover 13 that closes the opening of the housing body 12. Such an HDD 10 may be used by being incorporated in a computer main body, for example, or may be used as a single external recording device independent of the computer main body.

  As shown in FIG. 2, the housing 11 accommodates a magnetic disk 16 mounted on the rotary shaft 15 and a magnetic head 17 facing the magnetic disk 16. The magnetic head 17 is fixed to the tip of an arm 19 that can swing around the swing shaft 18. At the time of recording and reproducing information on the magnetic disk 16, the arm 19 is driven to swing by the actuator 20 constituted by a magnetic circuit, and as a result, the magnetic head 17 is positioned on a desired recording track on the magnetic disk 16. Become.

  As apparent from FIG. 3, the spindle motor 22 is magnetically coupled to the rotating shaft 15. A central shaft 23 of the spindle motor 22 is fixed to the housing 11. The lower end of the central shaft 23 is fixed to the bottom wall of the housing body 12 by screws 24. When the cover 11 is coupled to the housing main body 12, the upper end of the central shaft 23 is screwed to the cover 13 with a screw 25.

  The rotary shaft 15 is connected to the central shaft 23 via a bearing 26 so as to be relatively rotatable. Magnetic disks 16 and spacing rings 28 are alternately stacked on an outer flange 27 formed at the lower end of the rotary shaft 23. By the action of the spacing ring 28, the plurality of magnetic disks 16 are arranged at equal intervals in the axial direction.

  A pressing clamp 31 is fixed to the tip of the rotating shaft 23. The pressing clamp 31 sandwiches the stacked magnetic disk 16 and the spacing ring 28 between the flange 27. The pressing clamp 31 includes a flat plate body 33 that is fixed to the tip of the rotating shaft 15 by a plurality of screws 32 that are arranged at equal intervals on one virtual circle around the center of the rotating shaft 15.

  FIG. 4 shows a pressing clamp 31 according to the first embodiment of the present invention. The flat plate body 33 of the pressing clamp 31 is formed with a plurality of screw holes 36 along one virtual circle 35. Each screw hole 36 receives a corresponding screw 32. The pressing clamp 31 is provided with a rigidity suppressing mechanism 37 that relatively reduces the rigidity of the flat plate body 33 in an intermediate region along the virtual circle 35 between the screw hole regions as compared with the screw hole region. The rigidity suppressing mechanism 37 includes an annular wall 38 that rises from the outer edge of the flat plate body 33 to increase the rigidity of the pressing clamp 31 and a notch 39 formed on the top surface of the annular wall 38 in the intermediate region. Prepare.

  According to the rigidity suppressing mechanism 37, the rigidity of the annular wall 38 is suppressed in the intermediate region by the action of the notch 39. Therefore, even if a pushing force acts on the intermediate region when the screw 32 is tightened, the pushing force is absorbed by the elasticity of the middle region. As a result, the deformation of the pressing clamp 31 is suppressed, and the deformation, that is, the undulation of the magnetic disk 16 in contact with the outer edge of the pressing clamp 31 is avoided.

  As shown in FIG. 5, the flying height W of the flying slider 17a of the magnetic head 17 is defined at the center of the flying slider 17a. If the undulation of the magnetic disk 16a is eliminated, the possibility that the head element 17b located at the rear end of the flying slider 17a approaches the disk surface decreases. On the other hand, if waviness occurs in the magnetic disk 16b, the possibility that the head element 17b contacts the disk surface increases even if the flying height W of the flying slider 17a is maintained. In particular, on the inner peripheral side of the magnetic disk 16b where waviness increases, the peripheral speed of the disk surface decreases, so that the flying height of the flying slider 17a decreases and the risk of collision further increases. That is, by the function of the rigidity suppressing mechanism 37, the flying height of the flying slider 17a can be set as low as possible while avoiding a collision with the disk surface.

  The pressing clamp 31 may be formed by pressing using aluminum or stainless steel, for example, or may be formed by cold forging using duralumin. The material of the pressing clamp 31 is preferably selected in consideration of the strength and rigidity of the molded pressing clamp 31 and the thermal expansion coefficient. For example, aluminum is selected for the magnetic disk 16 employing an aluminum disk substrate, and stainless steel is selected for the magnetic disk 16 employing a glass disk substrate.

  In the case of employing press working, for example, as shown in FIG. 6, a tapered surface 40 connected to the top surface of the annular wall 38 may be provided in the notch 39. If such a tapered surface 40 is formed, the notch 39 can be easily formed by pressing. As shown in FIG. 7, a curved surface 41 may be formed at the joint between the bottom surface of the notch 39 and the tapered surface 40, or at the joint between the top surface of the annular wall 38 and the tapered surface 40. According to such a curved surface 41, stress is not concentrated at the joint between the bottom surface of the notch 39 and the tapered surface 40 or the joint between the top surface of the annular wall 38 and the tapered surface 40, and as a result, the pressing clamp 31 is rotated by the rotating shaft 15. It is possible to avoid the tightening force of the screws 32 from being weakened when the screws 32 are fixed to each other.

  FIG. 8 is a graph showing the amount of waviness of the 0.8 mm thick aluminum magnetic disk 16 pressed by the pressing clamp 31. In this graph, the vertical axis indicates the amount of sinking that occurs in the magnetic disk 16 due to the tightening force of the screw 32. According to this sinking amount, the amount of lowering of the disk surface during tightening is defined based on the position of the disk surface when the tightening force of the screw 32 is not acting on the pressing clamp 31. The amount of waviness was measured on the disk surface located at the outer edge of the pressing clamp 31. On the vertical axis of the graph, the circumferential position of the disc surface equally divided along the outer edge of the pressing clamp 31 is defined.

  As can be seen from FIG. 8, when the magnetic disk 16 is fixed using a conventional pressing clamp having an annular wall in which notches are not formed, the screw hole region is located between the screw hole region and the intermediate region between the screw hole regions. The maximum waviness of about 25 μm occurs. On the other hand, when the cutout 39 is provided in the annular wall 38 (as shown in FIG. 6), although the sinking of about 25 μm occurs almost uniformly in the circumferential direction of the pressing clamp 31, the swell is up to about 3 μm. It turns out that it is suppressed. Therefore, the presence of the notch 39 suppresses the rigidity of the annular wall 38, and as a result, the disk surface of the magnetic disk 16 is flattened.

  FIG. 9 shows a pressing clamp 31a according to the second embodiment of the present invention. In the second embodiment, a notch 45 is formed on the outer peripheral surface of the annular wall 38. According to such a notch 45, the rigidity of the annular wall 38 is suppressed in the intermediate region, and as a result, the disk surface of the magnetic disk 16 is flattened as in the first embodiment described above. Note that the same reference numerals are given to configurations that exhibit the same functional effects as those of the first embodiment described above, and detailed descriptions thereof are omitted.

  For example, as shown in FIG. 10, a balancer 46 may be attached to the pressing clamp 31 a so as to equalize the centrifugal force of the rotating magnetic disk 16 and suppress the vibration of the rotating magnetic disk 16. Such a balancer 46 is formed of a laminate of, for example, stainless steel (SUS) 47 and an adhesive 48. The balancer 46 is bonded to the inner wall surface of the annular wall 38 with an adhesive 49. In the annular wall 38, the inner peripheral surface of the annular wall 38 is continuous regardless of the presence of the notch 45. Therefore, even if the balancer 46 is accidentally detached from the annular wall 38, the detached balancer 46 is magnetically applied from the pressing clamp 31a. It does not fall toward the disk 16.

  FIG. 11 shows a pressing clamp 31b according to a third embodiment of the present invention. In the third embodiment, the rigidity suppressing mechanism 37 includes a through hole 51 formed in the flat plate main body 33 in an intermediate region along the virtual circle 35 between the screw hole regions. One through hole 51 may be formed in each intermediate region, or a plurality of through holes 51 may be formed in each intermediate region as shown. According to such a pressing clamp 31b, as a result of suppressing the rigidity of the flat plate body 33 in the intermediate region, the disk surface of the magnetic disk 16 is flattened as in the first and second embodiments described above. Note that the same reference numerals are given to configurations that exhibit the same functional effects as those of the first embodiment described above, and detailed descriptions thereof are omitted.

  When a plurality of through holes 51 are formed for each intermediate region, through holes 51a and 51b having different diameters may be provided as shown in FIG. 12, for example. In this way, the rigidity of the flat plate body 33 can be changed depending on the circumferential position of the flat plate body 33, and the deformation of the flat plate body 33 can be finely adjusted.

  FIG. 12 shows a pressing clamp 31c according to the fourth embodiment of the present invention. In the fourth embodiment, an annular wall 55 rising from the outer edge of the flat plate body 33 is formed on the flat plate body 33. As is apparent from FIG. 14, the thickness D of the annular wall 55 is formed to be thicker than the thickness of the flat plate body 33. Therefore, the rigidity of the outer edge of the flat plate body 33 in contact with the magnetic disk 16 is increased, while the rigidity of the screw hole 36 region of the flat plate body 33 is relatively weakened. As a result, even if the fastening force of the screw 32 is applied, the deformation of the flat plate body 33 is absorbed around the screw hole 36 and the deformation is suppressed at the outer edge of the flat plate body 33 in which the annular wall 55 is formed. Therefore, the disk surface of the magnetic disk 16 is flattened. Such a pressing clamp 31c may be ground from a metal block material. Note that the same reference numerals are given to configurations that exhibit the same functional effects as those of the first embodiment described above, and detailed descriptions thereof are omitted.

It is a perspective view which shows the external appearance of a hard disk drive (HDD). It is a top view which shows the internal structure of HDD. FIG. 3 is a partially enlarged cross-sectional view taken along line 3-3 in FIG. 2. It is a perspective view which shows the pressing clamp which concerns on 1st Embodiment of this invention. It is a figure which shows the relationship between the flying slider of a magnetic head, and the disk surface of a magnetic disk. It is a perspective view of the pressing clamp which shows the modification of a notch. It is a side view of the annular wall which shows the other modification of a notch. It is a graph which shows the amount of waviness of a magnetic disk. It is a perspective view which shows the pressing clamp which concerns on 2nd Embodiment of this invention. It is a partially expanded view of an annular wall. It is a perspective view which shows the pressing clamp which concerns on 3rd Embodiment of this invention. It is a partial enlarged plan view of a flat plate main body. It is a perspective view which shows the pressing clamp which concerns on 4th Embodiment of this invention. FIG. 14 is a partially enlarged sectional view taken along line 14-14 in FIG. 13.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Recording disk apparatus, 15 Rotating shaft, 16 Magnetic disk as recording disk, 27 Flange, 31, 31a, 31a, 31c Press clamp, 32 Screw, 33 Flat plate main body, 35 Virtual circle, 36 Screw hole, 37 Rigidity suppression mechanism, 38 annular wall, 39, 45 notch, 40 tapered surface, 41 curved surface, 51 through hole, 51a through hole as large hole, 51b through hole as small hole, 55 thick annular wall.

Claims (4)

A rotary shaft having a flange, a disc mounted on the rotary shaft, a pressing clamp that sandwiches the disc between the flanges, and a flat plate body of the pressing clamp that is arranged along a virtual circle around the center of the rotating shaft. The continuity of the annular wall is maintained in the middle region along the imaginary circle between the screw hole areas of the flat plate body, the screw fixed to the tip of the rotating shaft, the annular wall rising from the surface of the flat plate body to increase the rigidity of the flat plate body And a notch that crosses the top surface of the annular wall in the radial direction . A flat plate body in which screw holes are drilled along a virtual circle, an annular wall that rises from the surface of the flat plate body to increase the rigidity of the flat plate body, and an annular region in the middle region along the virtual circle between the screw hole regions of the flat plate body A pressing clamp comprising: a notch that traverses the top surface of the annular wall in a radial direction while maintaining wall continuity.   The pressing clamp according to claim 2, wherein the notch includes a tapered surface continuous with the top surface.   4. The pressing clamp according to claim 2, wherein the notch is formed by a curved surface.

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