Disk device

Abstract

Provided is a disk device capable of suppressing a decrease in force for joining a boss and an inner surface of a through-hole. A disk device according to an embodiment includes a first suspension and a second suspension. The first suspension has a first base plate attached to the arm. The second suspension has a second base plate attached to the arm. The arm is provided with a through-hole, and has a first surface and a second surface that open the through-hole, and an inner surface that forms the through-hole. The first base plate has a first boss accommodated in the through hole and in contact with the inner surface. The second base plate has a second boss accommodated in the through hole and in contact with the inner surface. At least a portion of the second boss is held between the inner surface and the first boss.

Description

[0001] This application claims priority based on Japanese Patent Application No. 2023-124356 (filing date: July 31, 2023). The present application incorporates the entire contents of the basic application by reference. Technical Field

[0002] An embodiment of the present invention relates to a disk device. Background Art

[0003] A disk device such as a hard disk drive (HDD) has a magnetic disk and a head stack assembly (HSA). The HSA has a rotating carriage, a base plate mounted on an arm of the carriage, a load beam extending from the base plate, a flexure mounted on the load beam, and a magnetic head mounted on the flexure.

[0004] The base plate has a boss. A through hole is provided in the arm for the boss to be embedded. The base plate is mounted on the arm by the boss engaging with the inner surface of the arm forming the through hole. The slide has a plurality of arms, and two base plates are mounted on the arms other than the two ends of the plurality of arms.

[0005] For example, when the arm is thin, the through hole becomes short, and the length and arrangement of the two bosses inserted into the through hole are limited. Due to this limitation, the force for joining at least one of the bosses to the inner surface of the through hole may become insufficient. Summary of the invention

[0006] An embodiment of the present invention provides a disk device capable of suppressing a decrease in the force for joining a boss to an inner surface of a through hole.

[0007] The disk device of this embodiment comprises a first magnetic head, a second magnetic head, a slide, a first suspension and a second suspension. The slide has an arm and is configured to rotate. The first suspension has a first base plate mounted on the arm and holds the first magnetic head. The second suspension has a second base plate mounted on the arm and holds the second magnetic head. The arm is provided with a through hole and has a first surface where the through hole opens, a second surface located on the opposite side of the first surface and where the through hole opens, and an inner surface forming the through hole. The first base plate has a third surface facing the first surface and a first boss protruding from the third surface and accommodated in the through hole and in contact with the inner surface. The second base plate has a fourth surface facing the second surface and a second boss protruding from the fourth surface and accommodated in the through hole and in contact with the inner surface. At least a portion of the second boss is held between the inner surface and the first boss. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 This is an exemplary perspective view showing the HDD according to the first embodiment in an exploded manner.

[0009] Figure 2 This is an exemplary cross-sectional view showing a part of the HDD according to the first embodiment.

[0010] Figure 3 It is an exemplary plan view partially showing the HGA and the arm according to the first embodiment.

[0011] Figure 4 This is an exemplary cross-sectional view partially showing a plurality of HGAs and a plurality of arms according to the first embodiment.

[0012] Figure 5 This is an exemplary cross-sectional view partially showing the arm and the base plate of the first embodiment.

[0013] Figure 6 This is an exemplary cross-sectional view partially showing the arm and the base plate of the second embodiment.

[0014] Figure 7 This is an exemplary cross-sectional view partially showing the arm and the base plate of the third embodiment.

[0015] Description of Reference Numerals

[0016] 10…Hard disk drive (HDD), 11…Casing, 25a…Bottom, 31…Support shaft, 35…Slide, 42…Arm, 42a, 42b…Seat, 45…Riveting hole, 45a, 200…Inner surface, 51…Head, 52…Suspension, 55, 55U, 55D…Base plate, 62, 62U, 62D…Boss, 71U, 71D…Plane, 81…Outer ring portion, 81a…Outer peripheral surface, 81c…Contact area, 81d…Separation area, 82, 301…Inner ring portion, 82a…Outer peripheral surface, 82b…Inner peripheral surface, 87…Outer peripheral surface, 88…Inner peripheral surface, 93…End surface, 201…First inner surface, 202…Second inner surface. DETAILED DESCRIPTION

[0017] (First embodiment)

[0018] Below, refer to Figures 1 to 5 , the first embodiment is described. In addition, in this specification, sometimes the constituent elements and the description of the elements involved in the embodiment are recorded in multiple expressions. The constituent elements and their descriptions are just examples and are not limited to the descriptions in this specification. The constituent elements can also be identified by names different from the names in this specification. In addition, the constituent elements can also be described by expressions different from the descriptions in this specification.

[0019] In the following description, "suppress" is defined as, for example, preventing an event, action, or influence from occurring, or reducing the degree of an event, action, or influence.

[0020] Figure 1 This is an exemplary perspective view showing an exploded hard disk drive (HDD) 10 according to the first embodiment. The HDD 10 is an example of a disk device, and may also be called an electronic device, a storage device, an auxiliary storage device, or a magnetic disk device.

[0021] like Figure 1 As shown, HDD 10 has a housing 11, a plurality of magnetic disks 12, a spindle motor 13, a head stack assembly (HSA) 14, a voice coil motor (VCM) 15, a ramp load mechanism 16, and a printed circuit board (PCB) 17. The magnetic disk 12 may also be referred to as a disk or a platter.

[0022] like Figure 1 As shown, in this specification, for convenience, the Z axis and the Z direction are defined. The Z axis is set along the thickness of the HDD 10. The Z direction is a direction along the Z axis, including the +Z direction indicated by the arrow of the Z axis and the -Z direction which is the opposite direction of the arrow of the Z axis.

[0023] The housing 11 accommodates a plurality of magnetic disks 12, a spindle motor 13, an HSA 14, a VCM 15, and a ramp load mechanism 16. The housing 11 has a base 21, an inner cover 22, and an outer cover 23. In addition, the housing 11 is not limited to this example.

[0024] The base 21 is formed in a substantially rectangular box shape that is open in the +Z direction. The base 21 has a bottom wall 25 and a side wall 26. The bottom wall 25 is formed in a substantially rectangular (quadrilateral) plate shape that extends in a manner substantially orthogonal to the Z direction. The bottom wall 25 has a bottom surface 25a that faces substantially in the +Z direction. The side wall 26 protrudes from the edge of the bottom wall 25 in the substantially +Z direction and is formed in a substantially rectangular frame shape.

[0025] The inner cover 22 is attached to the end of the side wall 26 in the +Z direction by screws, for example, to close the base 21. The outer cover 23 covers the inner cover 22 and is attached to the end of the side wall 26 in the +Z direction by welding, for example.

[0026] The inner cover 22 is provided with a vent 27. Furthermore, the outer cover 23 is provided with a vent 28. Components are mounted inside the base 21, and after the inner cover 22 and the outer cover 23 are mounted on the base 21, the air inside the housing 11 is extracted from the vents 27 and 28. Furthermore, the inside of the housing 11 is filled with a gas different from air.

[0027] The gas filled into the housing 11 is, for example, a low-density gas having a lower density than air, a low-reactivity inert gas, etc. For example, helium gas is filled into the housing 11. Alternatively, other fluids may be filled into the housing 11.

[0028] The vent 28 of the cover 23 is blocked by a seal 29. The seal 29 seals the vent 28 airtightly, and restricts leakage of the fluid filling the interior of the housing 11 from the vent 28 to the outside of the housing 11.

[0029] The plurality of magnetic disks 12 are formed in a disk shape extending perpendicularly to the Z direction. The plurality of magnetic disks 12 are arranged at intervals in the Z direction. Magnetic recording layers are provided on both surfaces of the magnetic disks 12 .

[0030] The spindle motor 13 supports a plurality of magnetic disks 12. The plurality of magnetic disks 12 are held by, for example, a clamp spring at a hub of the spindle motor 13. The spindle motor 13 rotates the plurality of magnetic disks 12 in an integrated manner.

[0031] The housing 11 further includes a support shaft 31 spaced apart from the magnetic disk 12. The support shaft 31 protrudes, for example, substantially in the +Z direction from the bottom surface 25a of the bottom wall 25. The HSA 14 is rotatably supported by the support shaft 31.

[0032] The HSA 14 is rotatable around a central axis Axh. The central axis Axh is a virtual axis extending substantially in the Z direction. The central axis Axh is, for example, the center of rotation of the HSA 14 and is also the central axis of the support shaft 31 .

[0033] The HSA 14 has a carriage 35 , a plurality of head gimbal assemblies (HGAs) 36 , and a flexible printed circuit (FPC) 37 . The carriage 35 has an actuator block 41 and a plurality of arms 42 .

[0034] The actuator block 41 and the plurality of arms 42 are integrally formed of, for example, an aluminum alloy. In addition, the materials of the actuator block 41 and the arms 42 are not limited to this example.

[0035] The actuator block 41 is attached to the support shaft 31 via a bearing so as to be rotatable around the central axis Axh, for example. Thus, the carriage 35 is rotatable around the central axis Axh of the support shaft 31 .

[0036] Figure 2 1 is an exemplary cross-sectional view showing a portion of the HDD 10 according to the first embodiment. Figure 2 As shown, a plurality of arms 42 protrude from the actuator block 41 in a direction substantially perpendicular to the central axis Axh. Alternatively, the HSA 14 may be divided so that the arm 42 protrudes from each of the plurality of actuator blocks 41.

[0037] Figure 3 FIG. 4 is an illustrative top view partially showing the HGA 36 and the arm 42 of the first embodiment. Figure 3 As shown, in this specification, for convenience, an X-axis and a Y-axis are also defined. The X-axis, the Y-axis, and the Z-axis are orthogonal to each other. The Y-axis is provided along the arm 42. Moreover, in this specification, an X direction and a Y direction are also defined. The X direction is a direction along the X-axis, including the +X direction indicated by the arrow of the X-axis and the -X direction which is the opposite direction of the arrow of the X-axis. The Y direction is a direction along the Y-axis, including the +Y direction indicated by the arrow of the Y-axis and the -Y direction which is the opposite direction of the arrow of the Y-axis.

[0038] The plurality of arms 42 protrude in the +Y direction from the actuator block 41. Therefore, the Y direction is the longitudinal direction of the arm 42. The X direction is the short-side direction of the arm 42. The X direction and the Y direction change when the carriage 35 rotates around the central axis Axh.

[0039] like Figure 2 As shown, the plurality of arms 42 are arranged at intervals in the Z direction. Each of the arms 42 is formed in a plate shape that can enter the gap between the adjacent magnetic disks 12. The plurality of arms 42 extend substantially in parallel.

[0040] Figure 4 FIG. 2 is an exemplary cross-sectional view partially showing a plurality of HGAs 36 and a plurality of arms 42 of the first embodiment. Figure 4 As shown, each of the plurality of arms 42 has two seat surfaces 42a and 42b. The seat surface 42a is an example of a first surface, and the seat surface 42b is an example of a second surface.

[0041] Seat surfaces 42a and 42b are provided at the ends of the arm 42 in the +Y direction. Seat surface 42a is formed substantially flat and faces substantially in the +Z direction. Seat surface 42b is located on the opposite side of seat surface 42a. Seat surface 42b is formed substantially flat and faces substantially in the -Z direction.

[0042] A caulking hole 45 is provided in each of the plurality of arms 42. The caulking hole 45 is an example of a through hole. The caulking hole 45 is a circular hole that penetrates the arm 42 in the Z direction substantially so as to be open in the seat surfaces 42a and 42b.

[0043] Each of the plurality of arms 42 further includes an inner surface 45a that forms (defines, partitions) the caulking hole 45. The inner surface 45a is a substantially cylindrical curved surface substantially along the Z direction. In the present embodiment, the diameter of the inner surface 45a is substantially constant.

[0044] Each of the plurality of HGAs 36 is attached to the seat surface 42a or the seat surface 42b so as to protrude substantially in the +Y direction from the arm 42. Thus, the plurality of HGAs 36 are arranged at intervals in the Z direction.

[0045] like Figure 2 As shown, the plurality of HGAs 36 include two HGAs 36E, a plurality of HGAs 36U, and a plurality of HGAs 36D. HGAs 36E, 36U, and 36D are substantially identical to each other or are substantially mirror-symmetrical except for the points described below. In the following description, the common features of HGAs 36E, 36U, and 36D are described as the features of HGAs 36.

[0046] Two HGAs 36E are attached to two arms 42 located at both ends of the plurality of arms 42. One HGA 36E is attached to a seat surface 42b of an arm 42 located at an end in the +Z direction. The other HGA 36E is attached to a seat surface 42a of an arm 42 located at an end in the -Z direction.

[0047] The plurality of HGAs 36U and 36D are located between the two HGAs 36E. The plurality of HGAs 36U are mounted on the seat surfaces 42a of the plurality of arms 42 located between the two HGAs 36E. The plurality of HGAs 36D are mounted on the seat surfaces 42b of the plurality of arms 42 located between the two HGAs 36E. That is, the two HGAs 36U and 36D are mounted on the two seat surfaces 42a and 42b of the plurality of arms 42 between the two HGAs 36E.

[0048] like Figure 3 As shown, each of the plurality of HGAs 36 has a magnetic head 51 and a suspension 52. The magnetic head 51 may also be called a slider. The magnetic head 51 and the suspension 52 of the HGA 36U are examples of a first magnetic head and a first suspension. The magnetic head 51 and the suspension 52 of the HGA 36D are examples of a second magnetic head and a second suspension.

[0049] The magnetic head 51 records and reproduces information on a corresponding one of the plurality of magnetic disks 12. In other words, the magnetic head 51 reads and writes information on the magnetic disk 12.

[0050] The suspension 52 is attached to the arm 42 and holds the magnetic head 51. The suspension 52 includes a base plate 55, a load beam 56, and a flexure 57.

[0051] The base plate 55 and the load beam 56 are made of, for example, stainless steel. The materials of the base plate 55 and the load beam 56 are not limited to this example. The base plate 55 and the load beam 56 may be made of different materials.

[0052] like Figure 4 As shown, the base plate 55 includes a plate 61 and a boss 62. The plate 61 is formed into a substantially quadrilateral plate shape substantially orthogonal to the Z direction. The boss 62 protrudes from the plate 61. The boss 62 is formed into a substantially cylindrical shape and is fitted into the rivet hole 45 of the arm 42.

[0053] The base plate 55 is mounted on the arm 42 of the carriage 35 by riveting the boss 62 to the arm 42. Alternatively, the base plate 55 may be mounted on the arm 42 by other methods.

[0054] The load beam 56 is formed into a plate shape thinner than the base plate 55. Figure 3 As shown, the load beam 56 is mounted on the plate 61 by, for example, spot welding. Alternatively, the load beam 56 may be mounted on the plate 61 by other means.

[0055] The load beam 56 extends substantially in the +Y direction from the plate 61 . For example, the load beam 56 extends obliquely from the plate 61 toward the corresponding magnetic disk 12 .

[0056] The flexure 57 is a flexible printed wiring board formed in a long and narrow strip shape and has, for example, a metal backing layer, an insulating base layer, a conductive layer, and an insulating cover layer.

[0057] The flexure 57 extends along the arm 42, the load beam 56, and the plate 61. The flexure 57 is attached to the load beam 56 and the plate 61 by, for example, spot welding.

[0058] A gimbal portion 65 is provided at the end portion in the +Y direction of the flexure 57. The magnetic head 51 is attached to the gimbal portion 65. The gimbal portion 65 holds the magnetic head 51 so as to be swingable.

[0059] like Figure 1 As shown, the end of the flexure 57 in the -Y direction is connected to one end of the FPC 37 mounted on the actuator block 41. Therefore, the flexure 57 electrically connects the magnetic head 51 and the FPC 37. The other end of the FPC 37 is connected to a connector provided on the bottom wall 25, for example.

[0060] The carriage 35, the magnetic head 51, and the suspension 52 are accommodated in the housing 11. The suspension 52 of the HGA 36D is closer to the bottom surface 25a than the suspension 52 of the HGA 36U. The arrangements of the HGA 36U and 36D may be reversed.

[0061] The VCM 15 includes a voice coil, a pair of yokes, and a magnet provided on the yokes. The voice coil is held by an actuator block 41. The VCM 15 moves the magnetic head 51 to a desired position by rotating the carriage 35 around the central axis Axh.

[0062] When the head 51 moves to the outer edge of the magnetic disk 12 by the rotation of the HSA 14 realized by the VCM 15, Figure 1 The ramp loading mechanism 16 holds the magnetic head 51 in a position spaced apart from the magnetic disk 12 .

[0063] The PCB 17 is, for example, a rigid substrate such as a glass epoxy substrate, a multi-layer substrate, a build-up substrate, etc. The PCB 17 is disposed outside the housing 11 and mounted on the bottom wall 25 .

[0064] Various electronic components such as a relay connector electrically connected to the FPC 37, an interface (I / F) connector connected to a host computer, and a controller for controlling the operation of the HDD 10 are mounted on the PCB 17. The relay connector is electrically connected to the FPC 37 via a connector provided on the bottom wall 25. The controller of the PCB 17 controls, for example, the spindle motor 13, the VCM 15, and the magnetic head 51.

[0065] like Figure 4 As shown, in the following description, the base plate 55 and the boss 62 of the HGA36U are referred to as a base plate 55U and a boss 62U. The base plate 55U is an example of a first base plate. The boss 62U is an example of a first boss.

[0066] In the following description, the base plate 55 and the boss 62 of the HGA 36D are referred to as a base plate 55D and a boss 62D. The base plate 55D is an example of a second base plate. The boss 62D is an example of a second boss.

[0067] The plate 61 of the base plate 55U has a flat surface 71U. The flat surface 71U is an example of a third surface. The flat surface 71U is formed substantially flat and faces substantially in the -Z direction. The flat surface 71U faces the seat surface 42a and contacts the seat surface 42a.

[0068] The boss 62U protrudes from the plane 71U in the substantially −Z direction and is received in the rivet hole 45. The base plate 55U is attached to the arm 42 by rivet-joining the boss 62U to the inner surface 45a of the rivet hole 45.

[0069] The plate 61 of the base plate 55D has a flat surface 71D. The flat surface 71D is an example of a fourth surface. The flat surface 71D is formed substantially flat and faces substantially in the +Z direction. The flat surface 71D faces the seat surface 42b and contacts the seat surface 42b.

[0070] The boss 62D protrudes from the plane 71D in the substantially +Z direction and is received in the rivet hole 45. The base plate 55D is attached to the arm 42 by rivet-joining the boss 62D to the inner surface 45a of the rivet hole 45.

[0071] The base plate 55U is provided with an insertion hole 75U. The insertion hole 75U passes through the inner side of the substantially cylindrical boss 62U and penetrates the base plate 55U substantially in the Z direction. Furthermore, the base plate 55D is provided with an insertion hole 75D. The insertion hole 75D passes through the inner side of the substantially cylindrical boss 62D and penetrates the base plate 55D substantially in the Z direction.

[0072] The caulking hole 45 and the insertion holes 75U, 75D extend along a common central axis Axs. In other words, the caulking hole 45 and the insertion holes 75U, 75D are arranged on the same axis. In addition, the central axes of the caulking hole 45 and the insertion holes 75U, 75D may be different from each other.

[0073] The center axis Axs is a virtual axis extending substantially in the Z direction. That is, the center axis Axh of rotation of the HSA 14 is arranged substantially parallel to the center axis Axs of the caulking hole 45. In addition, the caulking holes 45 of the plurality of arms 42 are provided on the common center axis Axs.

[0074] In the following, for convenience, the axial direction, radial direction, and circumferential direction are defined. The axial direction is the direction along the central axis Axs. The axial direction is equal to the Z direction. The radial direction is the direction orthogonal to the central axis Axs, including multiple directions orthogonal to the central axis Axs. The circumferential direction is the direction of rotation around the central axis Axs, including the direction of clockwise rotation and the direction of counterclockwise rotation around the central axis Axs.

[0075] Figure 5 FIG. 4 is an exemplary cross-sectional view partially showing the arm 42 and the base plates 55U and 55D of the first embodiment. Figure 5 As shown, the boss 62U includes an outer ring portion 81, an inner ring portion 82, and an intermediate portion 83. The outer ring portion 81 is an example of a first portion, and the inner ring portion 82 is an example of a second portion.

[0076] The outer ring portion 81 is a substantially cylindrical portion that protrudes from the plane 71U in the substantially -Z direction. The outer ring portion 81 has an outer peripheral surface 81a and an inner peripheral surface 81b. The outer peripheral surface 81a is an example of a first outer side surface. The inner peripheral surface 81b is an example of a first inner side surface.

[0077] The outer peripheral surface 81a is a substantially cylindrical curved surface facing radially outward. The outer peripheral surface 81a faces the inner surface 45a of the caulking hole 45. The outer peripheral surface 81a has a contact region 81c and a separation region 81d.

[0078] The contact area 81c is a substantially cylindrical curved surface that is separated from the plane 71U in the substantially -Z direction and extends in the circumferential direction. The contact area 81c of the outer peripheral surface 81a of the outer ring portion 81 is in contact with the inner surface 45a. The substantially entire area of ​​the contact area 81c in the circumferential direction is in contact with the inner surface 45a. In the present embodiment, the contact area 81c is sunken into the inner surface 45a by riveting the boss 62U to the inner surface 45a. Thus, the contact area 81c of the outer peripheral surface 81a is joined to the inner surface 45a.

[0079] The separation region 81d is a substantially cylindrical curved surface located between the plane 71U and the contact region 81c and extending in the circumferential direction. The contact region 81c and the separation region 81d form a continuous substantially cylindrical curved surface. The separation region 81d is spaced apart from the inner surface 45a.

[0080] The inner peripheral surface 81b is located on the opposite side of the outer peripheral surface 81a. The inner peripheral surface 81b is a substantially cylindrical curved surface facing radially inward. In other words, the inner peripheral surface 81b faces the inner side of the rivet hole 45. The thickness T1 of the outer ring portion 81 is substantially constant. The thickness T1 is the distance between the outer peripheral surface 81a and the inner peripheral surface 81b.

[0081] In this embodiment, the outer peripheral surface 81a and the inner peripheral surface 81b of the outer ring portion 81 are formed into a substantially conical shape that tapers toward the +Z direction. Therefore, the distance between the separation region 81d and the inner surface 45a is maximum at the end of the separation region 81d in the +Z direction.

[0082] The inner ring portion 82 is a substantially annular portion that is further away from the plane 71U in the -Z direction than the outer ring portion 81. The inner ring portion 82 has an outer peripheral surface 82a and an inner peripheral surface 82b. The outer peripheral surface 82a is an example of a second outer side surface. The inner peripheral surface 82b is an example of a second inner side surface.

[0083] The outer peripheral surface 82a is a substantially cylindrical curved surface facing radially outward. The outer peripheral surface 82a faces the inner surface 45a of the rivet hole 45. The diameter of the outer peripheral surface 82a of the inner ring portion 82 is smaller than the diameter of the outer peripheral surface 81a of the outer ring portion 81. The outer peripheral surface 82a is farther away from the inner surface 45a than the outer peripheral surface 81a. The outer peripheral surface 82a and the inner surface 45a face each other with a gap therebetween.

[0084] The inner peripheral surface 82b is located on the opposite side of the outer peripheral surface 82a. The inner peripheral surface 82b is a substantially cylindrical curved surface facing radially inward. In other words, the inner peripheral surface 82b faces the inner side of the rivet hole 45. The thickness T2 of the inner ring portion 82 is substantially constant. The thickness T2 is the distance between the outer peripheral surface 82a and the inner peripheral surface 82b.

[0085] The intermediate portion 83 is provided between the outer ring portion 81 and the inner ring portion 82. The inner ring portion 82 is connected to the outer ring portion 81 via the intermediate portion 83. In addition, the inner ring portion 82 may be directly connected to the outer ring portion 81. The intermediate portion 83 has an outer inclined surface 83a and an inner inclined surface 83b. The inner inclined surface 83b is an example of an inclined surface.

[0086] The outer inclined surface 83a extends obliquely relative to the central axis Axs between the end of the outer peripheral surface 81a in the -Z direction and the end of the outer peripheral surface 82a in the +Z direction. The inner inclined surface 83b is located on the opposite side of the outer inclined surface 83a. The inner inclined surface 83b extends obliquely relative to the central axis Axs between the end of the inner peripheral surface 81b in the -Z direction and the end of the inner peripheral surface 82b in the +Z direction.

[0087] The outer inclined surface 83a and the inner inclined surface 83b are formed into a generally conical shape with the front end tapering toward the -Z direction. In other words, the outer inclined surface 83a is formed into a generally conical shape extending between the outer peripheral surface 81a and the outer peripheral surface 82a and tapering toward the outer peripheral surface 82a. In addition, the inner inclined surface 83b is formed into a generally conical shape extending between the inner peripheral surface 81b and the inner peripheral surface 82b and tapering toward the inner peripheral surface 82b. The thickness T3 of the intermediate portion 83 is generally constant. The thickness T3 is the distance between the outer inclined surface 83a and the inner inclined surface 83b.

[0088] The thickness T1 of the outer ring portion 81 is smaller than the thickness T2 of the inner ring portion 82. The thickness T1 of the outer ring portion 81 is substantially equal to the thickness T3 of the middle portion 83. That is, the inner ring portion 82 is thicker than the outer ring portion 81 and thicker than the middle portion 83.

[0089] The length Lu of the boss 62U protruding from the plane 71U is greater than half Lh of the distance between the two seat surfaces 42a and 42b. The length Lu is the length of the boss 62U in the axial direction. The boss 62U has an outer peripheral surface 87 and an inner peripheral surface 88. The outer peripheral surface 87 is an example of an outer side surface. The inner peripheral surface 88 is an example of an inner side surface.

[0090] The outer peripheral surface 87 of the boss 62U includes the outer peripheral surface 81a of the outer ring portion 81, the outer peripheral surface 82a of the inner ring portion 82, and the outer inclined surface 83a of the intermediate portion 83. The outer peripheral surface 87 and the inner surface 45a face each other.

[0091] The inner peripheral surface 88 of the boss 62U includes the inner peripheral surface 81b of the outer ring portion 81, the inner peripheral surface 82b of the inner ring portion 82, and the inner inclined surface 83b of the intermediate portion 83. The inner peripheral surface 88 forms (defines, demarcates) the insertion hole 75U. The inner peripheral surface 88 faces the inside of the caulking hole 45.

[0092] The inner circumferential surface 82b of the inner ring portion 82 is located at a position closest to the inner side of the rivet hole 45 in the inner circumferential surface 88 of the boss 62U. The inner circumferential surface 82b is at least partially located between the central plane Pm and the seat surface 42b. That is, the inner circumferential surface 82b is located between the two seat surfaces 42a and 42b. The central plane Pm is an imaginary plane that is the center between the two seat surfaces 42a and 42b. In this embodiment, the center of the inner circumferential surface 82b in the axial direction is located between the central plane Pm and the seat surface 42b.

[0093] At least a portion of the boss 62D is held between the inner surface 45a and the boss 62U. In other words, at least a portion of the boss 62D overlaps with a portion of the boss 62U in the radial direction. In the present embodiment, at least a portion of the boss 62D is held between the inner surface 45a and the outer peripheral surface 82a of the inner ring portion 82.

[0094] The boss 62D has an outer peripheral surface 91, an inner peripheral surface 92, and an end surface 93. The outer peripheral surface 91 is a substantially cylindrical curved surface facing radially outward. The outer peripheral surface 91 faces the inner surface 45a of the caulking hole 45. The outer peripheral surface 91 has a contact area 91a and a separation area 91b.

[0095] The contact area 91a is a substantially cylindrical curved surface that is spaced from the plane 71D in the substantially +Z direction and extends in the circumferential direction. The contact area 91a of the outer peripheral surface 91 contacts the inner surface 45a. In the present embodiment, the contact area 91a is sunken into the inner surface 45a by riveting the boss 62D to the inner surface 45a. Thus, the contact area 91a of the outer peripheral surface 91 is joined to the inner surface 45a.

[0096] The separation region 91b is a substantially cylindrical curved surface located between the plane 71D and the contact region 91a and extending in the circumferential direction. The contact region 91a and the separation region 91b form a continuous substantially cylindrical curved surface. The separation region 91b is spaced apart from the inner surface 45a.

[0097] The inner peripheral surface 92 is located on the opposite side of the outer peripheral surface 91. The inner peripheral surface 92 is a substantially cylindrical curved surface facing radially inward. In other words, the inner peripheral surface 92 faces the inside of the rivet hole 45. The inner peripheral surface 92 of the boss 62D contacts the outer peripheral surface 82a of the inner ring portion 82.

[0098] The thickness of the boss 62D is substantially constant. However, the boss 62D is compressed between the inner surface 45a of the rivet hole 45 and the inner ring portion 82 of the boss 62U. Therefore, the thickness T4 of the portion of the boss 62D in contact with the inner ring portion 82 and the thickness of the portion spaced apart from the boss 62U may be different from each other. The thickness T4 is the distance between the outer peripheral surface 91 and the inner peripheral surface 92.

[0099] The thickness T4 of the boss 62D is thinner than the thickness T1 of the outer ring portion 81. In other words, the outer ring portion 81 is thicker than the boss 62D. For example, the boss 62D becomes thinner than the outer ring portion 81 by being compressed between the inner surface 45a and the inner ring portion 82. In addition, the thickness T4 of the boss 62D is not limited to this example.

[0100] In the present embodiment, the outer circumferential surface 91 and the inner circumferential surface 92 of the boss 62D are formed into a substantially conical shape that tapers toward the -Z direction. Therefore, the distance between the separation region 91b and the inner surface 45a is maximum at the end of the separation region 91b in the -Z direction.

[0101] The end surface 93 is located at the end of the boss 62D in the +Z direction. The +Z direction is an example of a direction in which the second boss protrudes from the fourth surface. The end surface 93 faces the outer ring portion 81 and the middle portion 83 of the boss 62U. In the present embodiment, the end surface 93 faces the outer inclined surface 83a of the middle portion 83.

[0102] The end face 93 is spaced apart from the boss 62U. The distance between the end face 93 and the boss 62U is greater than the maximum distance between the separation area 81d of the outer ring portion 81 and the inner surface 45a of the rivet hole 45. Moreover, the distance between the end face 93 and the boss 62U is greater than the maximum distance between the separation area 91b of the boss 62D and the inner surface 45a of the rivet hole 45.

[0103] like Figure 4 As shown, the shape of the boss 62 of the HGA 36E is different from the shapes of the bosses 62U and 62D. However, the shape of the boss 62 of the HGA 36E may be the same as the shape of the boss 62U, for example.

[0104] like Figure 3 As shown, the plate 61 of the base plate 55U is provided with a notch N. On the other hand, the plate 61 of the base plate 55D is not provided with a notch N, or is provided with a notch of a different shape. The notch N can be used to distinguish whether the base plate 55 is the base plate 55U or the base plate 55D.

[0105] The following is an example of a method for riveting the base plates 55U and 55D as a part of the method for manufacturing the HDD 10. The method for riveting the base plates 55U and 55D is not limited to the following method, and other methods may be used.

[0106] First, the bosses 62U and 62D are inserted into the caulking holes 45 . Figure 5 The bosses 62U and 62D before caulking are indicated by two-dot chain lines. The bosses 62U and 62D are inserted into the caulking hole 45 so that the inner ring portion 82 of the boss 62U overlaps with the boss 62D in the radial direction.

[0107] Before riveting, the diameter of the outer peripheral surface 81a of the outer ring portion 81 and the outer peripheral surface 91 of the boss 62D is smaller than the diameter of the inner surface 45a of the riveting hole 45. Therefore, before riveting, at least a portion of the outer peripheral surface 81a of the outer ring portion 81 and the outer peripheral surface 91 of the boss 62D in the circumferential direction is spaced apart from the inner surface 45a of the riveting hole 45.

[0108] Before riveting, the diameter of the outer peripheral surface 82a of the inner ring portion 82 is smaller than the diameter of the inner peripheral surface 92 of the boss 62D. Therefore, before riveting, at least a portion of the outer peripheral surface 82a of the inner ring portion 82 in the circumferential direction is spaced apart from the inner peripheral surface 92 of the boss 62D.

[0109] Next, the ball B passes through the caulking hole 45 and the insertion holes 75U and 75D. The ball B is made of, for example, stainless steel. The rigidity of the ball B is higher than the rigidity of the boss 62U and higher than the rigidity of the boss 62D.

[0110] The ball B first enters the insertion hole 75U. That is, when the ball B passes through the insertion holes 75U and 75D and the bosses 62U and 62D are riveted to the inner surface 45a, the boss 62U is located upstream and the boss 62D is located downstream. The diameter of the ball B is larger than the diameter of the inner peripheral surface 82b of the inner ring portion 82 before riveting. Therefore, the ball B, for example, contacts the inner inclined surface 83b of the intermediate portion 83.

[0111] The balls B push the inner inclined surface 83b in the -Z direction. The boss 62U is plastically deformed so as to be pulled in the -Z direction and expanded by the balls B. As a result, the outer peripheral surface 81a of the outer ring portion 81 contacts and engages with the inner surface 45a of the caulking hole 45.

[0112] The outer peripheral surface 82a of the inner ring portion 82 contacts the inner peripheral surface 92 of the boss 62D. The boss 62D is compressed by the inner ring portion 82 and plastically deformed to expand. As a result, the outer peripheral surface 91 of the boss 62D contacts the inner surface 45a of the rivet hole 45 and is bonded to the inner surface 45a.

[0113] The boss 62D is held between the inner surface 45a and the plastically deformed inner ring portion 82. According to another expression, the inner ring portion 82 presses the boss 62D toward the inner surface 45a. Therefore, the boss 62D is firmly engaged with the inner surface 45a.

[0114] On the other hand, outer peripheral surface 82a of inner ring portion 82 contacts inner peripheral surface 92 of boss 62D and engages with inner peripheral surface 92. Since boss 62D engages with inner surface 45a, outer peripheral surface 82a of inner ring portion 82 engages with inner surface 45a via boss 62D.

[0115] The boss 62D is engaged with the inner surface 45a by plastic deformation, and is pressed toward the inner surface 45a by the boss 62U. Thus, the boss 62D is firmly rivet to the inner surface 45a of the rivet hole 45.

[0116] The boss 62U is directly joined to the inner surface 45a by plastic deformation, and is indirectly joined to the inner surface 45a via the boss 62D. Thus, the boss 62U is also firmly riveted to the inner surface 45a of the rivet hole 45.

[0117] As the inner ring portion 82 expands, the diameter of the inner peripheral surface 82b of the inner ring portion 82 becomes larger than the diameter of the ball B. Therefore, the ball B passes through the insertion holes 75U and 75D and enters the next insertion hole 75U. The ball B passes through the insertion holes 75U and 75D of the plurality of base plates 55U and 55D in succession.

[0118] The inner inclined surface 83b is pushed toward the -Z direction by the ball B, and a curved surface 83c connected to the inner peripheral surface 82b is formed on the inner inclined surface 83b. In other words, the inner inclined surface 83b has the curved surface 83c. The curved surface 83c is a part of the inner inclined surface 83b. However, the curved surface 83c may also be the entire inner inclined surface 83b.

[0119] The curved surface 83c is formed into a curved conical shape that expands toward the central axis Axs. Therefore, the farther from the plane 71U, the greater the angle between the plane 71U and the curved surface 83c. The ball B bends the inner ring portion 82 and the middle portion 83 to form the curved surface 83c. In addition, the curved surface 83c may not be formed on the inner inclined surface 83b.

[0120] As described above, the base plates 55U and 55D are attached to the arm 42 by caulking. In addition, the boss 62 of the HGA 36E is attached to the arm 42 by general caulking. That is, the boss 62 of the HGA 36E is deformed to expand by the ball B and engages with the inner surface 45a of the arm 42.

[0121] In the HDD 10 of the first embodiment described above, the arm 42 has a seat surface 42a, a seat surface 42b located on the opposite side of the seat surface 42a, and an inner surface 45a. The arm 42 is provided with a rivet hole 45 opened on the seat surface 42a and the seat surface 42b. The inner surface 45a forms the rivet hole 45. The base plate 55U has a plane 71U facing the seat surface 42a and a boss 62U protruding from the plane 71U. The boss 62U is accommodated in the rivet hole 45 and contacts the inner surface 45a. The base plate 55D has a plane 71D facing the seat surface 42b and a boss 62D protruding from the plane 71D. The boss 62D is accommodated in the rivet hole 45 and contacts the inner surface 45a. At least a portion of the boss 62D is held between the inner surface 45a and the boss 62U.

[0122] When the arm 42 is thin between the seat surface 42a and the seat surface 42b, sometimes the contact area of ​​the boss 62U and the boss 62D directly contacting the inner surface 45a becomes smaller. On the other hand, the boss 62U of the present embodiment is engaged with the inner surface 45a by contacting with the inner surface 45a, and the boss 62D is held between the inner surface 45a and the boss 62U. That is, the boss 62U overlaps at least a part of the boss 62D. The boss 62D is engaged with the inner surface 45a by the boss 62D itself contacting with the inner surface 45a, and is firmly engaged with the inner surface 45a through the boss 62U. Moreover, the boss 62U is engaged with the inner surface 45a by the boss 62U itself contacting with the inner surface 45a, and is engaged with the inner surface 45a via the boss 62D by contacting with the boss 62D. Thus, even if the arm 42 is thinned between the seat surface 42a and the seat surface 42b, the force for joining the bosses 62U and 62D to the inner surface 45a can be suppressed from decreasing. Therefore, in the HDD 10 of this embodiment, the arm 42 can be thinned between the seat surface 42a and the seat surface 42b, thereby increasing the number of disks 12.

[0123] The boss 62U has an outer peripheral surface 87 facing the inner surface 45a. At least a portion of the boss 62D is held between the inner surface 45a and the outer peripheral surface 87. Thus, the boss 62D can be more firmly joined to the inner surface 45a than when it is held between two surfaces that do not face each other.

[0124] The outer peripheral surface 87 has an outer peripheral surface 81a and an outer peripheral surface 82a. The outer peripheral surface 81a contacts the inner surface 45a. The outer peripheral surface 82a is farther away from the inner surface 45a than the outer peripheral surface 81a. The outer peripheral surface 82a and the inner surface 45a face each other. At least a part of the boss 62D is held between the inner surface 45a and the outer peripheral surface 82a. Thus, compared with the case where the outer peripheral surface 87 with a constant diameter contacts the inner surface 45a and the boss 62D, the boss 62U can stably contact the inner surface 45a and can stably hold the boss 62D between the inner surface 45a and the outer peripheral surface 82a.

[0125] The boss 62U has inner circumferential surfaces 81b, 82b and an inner inclined surface 83b. The inner circumferential surface 81b is located on the opposite side of the outer circumferential surface 81a. The inner circumferential surface 82b is located on the opposite side of the outer circumferential surface 82a. The inner inclined surface 83b extends between the inner circumferential surface 81b and the inner circumferential surface 82b and tapers toward the inner circumferential surface 82b. The inner inclined surface 83b has a curved surface 83c connected to the inner circumferential surface 82b. The angle between the plane 71U and the curved surface 83c increases as it is farther from the plane 71U. In the riveting in which the boss 62U becomes the upstream and the boss 62D becomes the downstream, the ball B pushes the inner inclined surface 83b in the -Z direction to form a curved surface 83c on the inner inclined surface 83b. Since the balls B press the inner inclined surface 83 b , the outer peripheral surface 82 a comes into contact with the boss 62D more reliably, and the boss 62U can hold the boss 62D between the inner surface 45 a and the outer peripheral surface 82 a .

[0126] The end surface 93 of the boss 62D in the +Z direction where the boss 62D protrudes from the plane 71D is spaced apart from the boss 62U. Thus, the end surface 93 of the boss 62D can suppress the boss 62U from being pushed out of the caulking hole 45 in the axial direction.

[0127] The outer peripheral surface 87 has a contact area 81c that contacts the inner surface 45a, and a separation area 81d that is located between the contact area 81c and the plane 71U and is spaced apart from the inner surface 45a. The distance between the end surface 93 and the boss 62U is greater than the maximum distance between the separation area 81d and the inner surface 45a. Thus, the boss 62D can suppress the end surface 93 from contacting the boss 62U due to, for example, dimensional deviation.

[0128] The boss 62U has an outer ring portion 81 and an inner ring portion 82. The outer ring portion 81 protrudes from the plane 71U and contacts the inner surface 45a. The inner ring portion 82 is farther away from the plane 71U than the outer ring portion 81 and is thicker than the outer ring portion 81. At least a portion of the boss 62D is retained between the inner surface 45a and the inner ring portion 82. That is, the inner ring portion 82 that holds the boss 62D is thicker than the outer ring portion 81 that contacts the inner surface 45a. During riveting, the thick portion can be more firmly engaged than the thin portion. Therefore, the boss 62U can be more firmly engaged with the inner surface 45a via the boss 62D, and the boss 62D can be more firmly engaged with the inner surface 45a through the boss 62U.

[0129] The outer ring portion 81 is thicker than the boss 62D. Thus, the inner ring portion 82 of the boss 62D can be easily set thicker than when the boss 62D is thicker than the outer ring portion 81. Moreover, the boss 62D is compressed between the inner surface 45a and the inner ring portion 82 to become thinner. That is, the thinner the boss 62D is between the inner surface 45a and the inner ring portion 82, the more firmly the inner ring portion 82 holds the boss 62D, and thus, the boss 62D can be prevented from being separated from the rivet hole 45.

[0130] The boss 62U has an inner peripheral surface 88 facing the inner side of the rivet hole 45. When the boss 62U is engaged with the inner surface 45a by riveting, for example, the ball B pushes the inner peripheral surface 82b of the inner peripheral surface 88 that is located closest to the inner side of the rivet hole 45. That is, the boss 62U holds the boss 62D between the inner surface 45a and the boss 62U by the inner peripheral surface 82b being pushed by the ball B. The inner peripheral surface 82b is located between the seat surface 42a and the seat surface 42b. Therefore, the boss 62U pushed by the ball B can more directly press the boss 62D toward the inner surface 45a. Therefore, compared with the case where the inner peripheral surface 82b is located outside the rivet hole 45, the boss 62U can more reliably hold the boss 62D between the inner surface 45a and the boss 62U.

[0131] The inner peripheral surface 82b is at least partially located between the central plane Pm (the center between the seat surface 42a and the seat surface 42b) and the seat surface 42b. As a result, the boss 62U can increase the contact area between the boss 62U and the inner surface 45a compared to the case where the inner peripheral surface 82b is located between the central plane Pm and the seat surface 42a. Therefore, the boss 62U can be more firmly engaged with the inner surface 45a.

[0132] The length Lu of the boss 62U protruding from the plane 71U is greater than the half Lh of the distance between the seat surface 42a and the seat surface 42b. Thus, compared with the case where the length Lu of the boss 62U is less than the half Lh of the distance between the seat surface 42a and the seat surface 42b, the boss 62U can increase the contact area between the boss 62U and the inner surface 45a, and can increase the contact area between the boss 62U and the boss 62D. Therefore, even if the arm 42 is thinned between the seat surface 42a and the seat surface 42b, the boss 62U can be more firmly engaged with the inner surface 45a.

[0133] (Second embodiment)

[0134] Below, refer to Figure 6 , the second embodiment is described. In addition, in the description of the following multiple embodiments, sometimes a component having the same function as a component already described is marked with the same reference numeral as the component already described and the description is omitted. In addition, multiple components marked with the same reference numeral do not necessarily have all the same functions and properties, and may have different functions and properties corresponding to each embodiment.

[0135] Figure 6 FIG. 4 is an exemplary cross-sectional view partially showing the arm 42 and the base plates 55U and 55D of the second embodiment. Figure 6 As shown in FIG. 1 , the arm 42 of the second embodiment includes an inner surface 200 instead of the inner surface 45a. The inner surface 200 is substantially the same as the inner surface 45a except for the points described below.

[0136] The inner surface 200 has a first inner surface 201 and a second inner surface 202. The first inner surface 201 is closer to the seat surface 42a than the second inner surface 202. In the present embodiment, the first inner surface 201 is a substantially cylindrical curved surface connected to the seat surface 42a and extending from the seat surface 42a in the substantially -Z direction.

[0137] The boss 62U is caulked to the first inner surface 201. The outer peripheral surface 81a of the outer ring portion 81 contacts the first inner surface 201. As the outer peripheral surface 81a sinks into the first inner surface 201, a contact region 81c of the outer peripheral surface 81a is joined to the first inner surface 201.

[0138] The second inner surface 202 is closer to the seat surface 42b than the first inner surface 201. In the present embodiment, the second inner surface 202 is disposed between the seat surface 42b and the first inner surface 201. The second inner surface 202 is recessed radially outward from the first inner surface 201. Therefore, the diameter of the second inner surface 202 is larger than the diameter of the first inner surface 201. The second inner surface 202 can be formed, for example, by etching.

[0139] The boss 62D of the second embodiment has a thin portion 211 and a thick portion 212. The thin portion 211 is a substantially cylindrical portion protruding from the plane 71D in the substantially +Z direction. The thick portion 212 is a substantially annular portion further away from the plane 71D than the thin portion 211. In the present embodiment, the thick portion 212 is connected to the end of the thin portion 211 in the +Z direction.

[0140] The thick portion 212 has an outer peripheral surface 212a and an inner peripheral surface 212b. The outer peripheral surface 212a is a substantially cylindrical curved surface facing radially outward. The inner peripheral surface 212b is located on the opposite side of the outer peripheral surface 212a. The inner peripheral surface 212b is a substantially cylindrical curved surface facing radially inward. In other words, the inner peripheral surface 212b faces the inner side of the rivet hole 45.

[0141] The boss 62D is caulked to the second inner surface 202. The outer peripheral surface 212a is in contact with the second inner surface 202. The outer peripheral surface 212a is sunken into the second inner surface 202, so that the outer peripheral surface 212a and the second inner surface 202 are joined.

[0142] The inner peripheral surface 212b of the boss 62D contacts the outer peripheral surface 82a of the inner ring portion 82. The thick portion 212 of the boss 62D is held between the second inner surface 202 of the inner surface 200 and the outer peripheral surface 82a of the inner ring portion 82.

[0143] The thickness T5 of the thick portion 212 is thicker than the thickness T1 of the outer ring portion 81 . In other words, the thick portion 212 of the boss 62D is thicker than the outer ring portion 81 of the boss 62U. The thick portion 212 is thicker than the thin portion 211 .

[0144] For example, the diameter of the inner peripheral surface 212b of the thick portion 212 is substantially equal to the diameter of the inner peripheral surface 81b of the outer ring portion 81. However, the diameter of the outer peripheral surface 212a of the thick portion 212 is larger than the diameter of the outer peripheral surface 81a of the outer ring portion 81.

[0145] In the HDD 10 of the second embodiment described above, the boss 62U includes the outer ring portion 81 protruding from the plane 71U and in contact with the inner surface 200, and the inner ring portion 82 farther from the plane 71U than the outer ring portion 81. The thick portion 212 of the boss 62D is held between the inner surface 200 and the inner ring portion 82 and is thicker than the outer ring portion 81. During riveting, the thick portion can be joined more firmly than the thin portion. Therefore, the boss 62D can be joined to the inner surface 200 more firmly.

[0146] The inner surface 200 has a first inner surface 201 in contact with the outer ring portion 81 and a second inner surface 202 that is recessed from the first inner surface 201 and in contact with the boss 62D. Thus, the thick portion 212 of the boss 62D can be easily set thick.

[0147] (Third embodiment)

[0148] Below, refer to Figure 7 A third embodiment will be described. Figure 7 FIG. 4 is an exemplary cross-sectional view partially showing the arm 42 and the base plates 55U and 55D of the third embodiment. Figure 7 As shown in FIG. 1 , the boss 62U of the third embodiment includes an inner ring portion 301 instead of the inner ring portion 82. The inner ring portion 301 is substantially the same as the inner ring portion 82 except for the following points.

[0149] The thickness T2 of the inner ring portion 301 is less than or equal to the thickness T1 of the outer ring portion 81. Furthermore, the thickness T2 of the inner ring portion 301 is less than or equal to the thickness T4 of the boss 62D. The thickness T2 of the inner ring portion 301 is not limited to this example.

[0150] Before riveting, the outer peripheral surface 82a of the inner ring portion 301 is substantially continuous with the outer inclined surface 83a of the middle portion 83, forming an integral conical shape with the front end tapering toward the -Z direction. Furthermore, the inner peripheral surface 82b of the inner ring portion 301 is substantially continuous with the inner inclined surface 83b of the middle portion 83, forming an integral conical shape with the front end tapering toward the -Z direction.

[0151] The ball B enters the insertion hole 75U and pushes the inner peripheral surface 82b tapering toward the -Z direction substantially in the -Z direction. The boss 62U is plastically deformed by the ball B so as to be pulled and expanded in the -Z direction. As a result, the outer peripheral surface 81a of the outer ring portion 81 contacts the inner surface 45a of the caulking hole 45 and is bonded to the inner surface 45a.

[0152] Furthermore, the inner ring portion 301 is relatively thin, and therefore is bent relative to the middle portion 83 by being pressed by the balls B. As a result, the outer peripheral surface 82a of the inner ring portion 301 contacts the inner peripheral surface 92 of the boss 62D, and the boss 62D is held between the inner surface 45a and the inner ring portion 301. A groove that facilitates the bending of the inner ring portion 301 may be provided between the inner ring portion 301 and the middle portion 83.

[0153] The inner circumferential surface 82b of the inner ring portion 301 before riveting is tapered toward the -Z direction, so the force of the ball B pressing the inner circumferential surface 82b includes a force (component) that pushes the inner circumferential surface 82b radially outward. Therefore, the bending of the inner ring portion 301 and the joining of the outer circumferential surface 81a of the outer ring portion 81 to the inner surface 45a can be taken into account.

[0154] In the HDD 10 of the third embodiment described above, the boss 62U is bent so as to hold the boss 62D between the inner surface 45a and the inner ring portion 301. Thus, for example, the dimensional tolerance of the fitting between the inner ring portion 301 and the boss 62D can be set large.

[0155] Several embodiments of the present invention have been described, but these embodiments are provided as examples and are not intended to limit the scope of the invention. These new embodiments can be implemented in various other ways, and various omissions, substitutions, and changes can be made without departing from the scope of the invention. These embodiments and / or their variations are included in the scope and / or purpose of the invention, and are included in the invention described in the claims and the scope of their equivalents.

Claims

1. A disk device comprising: 1st head; The second magnetic head; a carriage having an arm configured to rotate; a first suspension having a first base plate mounted on the arm and holding the first magnetic head; and a second suspension having a second base plate mounted on the arm and holding the second magnetic head; The arm is provided with a through hole, and has a first surface where the through hole opens, a second surface located on the opposite side of the first surface and where the through hole opens, and an inner surface forming the through hole. The first base plate has a third surface facing the first surface and a first boss, wherein the first boss protrudes from the third surface, is received in the through hole and contacts the inner surface. The second base plate has a fourth surface facing the second surface and a second boss, the second boss protruding from the fourth surface, being received in the through hole and contacting the inner surface, At least a portion of the second boss is held between the inner surface and the first boss.

2. The disk device according to claim 1, The first boss has an outer side surface facing the inner surface. At least a portion of the second boss is held between the inner surface and the outer surface.

3. The disk device according to claim 2, The outer side surface includes a first outer side surface in contact with the inner surface and a second outer side surface which is farther from the inner surface than the first outer side surface and faces the inner surface. At least a portion of the second boss is held between the inner surface and the second outer surface.

4. The disk device according to claim 3, The first boss has a first inner side surface located on the opposite side of the first outer side surface, a second inner side surface located on the opposite side of the second outer side surface, and an inclined surface extending between the first inner side surface and the second inner side surface and tapering toward a front end of the second inner side surface. The inclined surface has a curved surface connected to the second inner side surface, The farther away from the third surface, the larger the angle between the third surface and the curved surface.

5. The disk device according to claim 2, An end surface of the second boss in a direction in which the second boss protrudes from the fourth surface is spaced apart from the first boss.

6. The disk device according to claim 5, The outer side surface has a contact area in contact with the inner surface, and a separation area located between the contact area and the third surface and spaced apart from the inner surface. The distance between the end surface and the first boss is greater than the maximum distance between the separation region and the inner surface.

7. The disk device according to claim 1, The first boss includes a first portion protruding from the third surface and in contact with the inner surface, and a second portion which is farther from the third surface than the first portion and thicker than the first portion. At least a portion of the second boss is held between the inner surface and the second portion.

8. The disk device according to claim 7, The first portion is thicker than the second boss.

9. The disk device according to claim 1, The first boss has an inner side surface facing the inner side of the through hole, A portion of the inner side surface that is located closest to the inner side of the through hole is located between the first surface and the second surface.

10. The disk device according to claim 9, A portion of the inner side surface that is located closest to the inner side of the through hole is at least partially located between the center between the first surface and the second surface and the second surface.

11. The disk device according to claim 1, The length of the first boss protruding from the third surface is greater than half of the distance between the first surface and the second surface.

12. The disk device according to claim 1, The first boss includes a first portion protruding from the third surface and in contact with the inner surface, and a second portion farther from the third surface than the first portion. At least a portion of the second boss is held between the inner surface and the second portion and is thicker than the first portion.

13. The disk device according to claim 12, The inner surface includes a first inner surface that contacts the first portion, and a second inner surface that is recessed from the first inner surface and contacts the second boss.

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