Motor, hard disc drive unit, air fan, and method for manufacturing motor

Abstract

To provide a motor structure in which a coil is less likely to sink into an electrodeposition coating film of a stator core.SOLUTION: A spindle motor 3 includes a stator core 50 in which a surface of a laminated structure of electromagnetic steel plates 52 is covered with a coating film 53, and the coating film 53 is an over-baked epoxy resin-containing electrodeposition coating film.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a motor, a hard disk drive, a blower, and a method for manufacturing a motor. [Background technology]

[0002] It is known that the surface of a stator core constituting a spindle motor, which is one type of motor, is electrochemically coated with an insulating material (Patent Document 1). The stator core extends radially outward and has a plurality of pole teeth (salient poles) arranged along the circumferential direction. Coils are wound around these pole teeth. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2008-72900 A Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, in the process of winding the coil around the pole teeth of the stator core, pressure may be applied to the coil, which may result in the coil being embedded in the electrodeposition coating film of the stator core.

[0005] An object of the present invention is to provide a motor structure in which the coil is less likely to sink into the electrocoat film of the stator core. [Means for solving the problem]

[0006] In order to solve the above problems, there is provided a motor including a stator core having a surface of a laminate of electromagnetic steel sheets covered with a coating film, the coating film being an overbaked epoxy resin-containing electrocoating film. Effect of the Invention

[0007] According to the present invention, in the motor, the coil is less likely to sink into the electrodeposition coating film of the stator core. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view of a hard disk drive 1. [Diagram 2] FIG. 2 is a partial cross-sectional view of the spindle motor 3. [Diagram 3] FIG. 2 is a top view of the stator core 50. [Figure 4] 2 is a partial cross-sectional view of a stator core 50 cut along a plane perpendicular to the axial direction. [Diagram 5] FIG. [Figure 6] FIG. 2 is a perspective view of the blower 300 with the lid 350 removed. [Figure 7] 2 is a cross-sectional view of a plane including the central axis of a shaft 380 in the blower 300. FIG. [Figure 8] FIG. 11 is a partial cross-sectional view of a spindle motor 103 according to a modified example. [Figure 9] FIG. 13 is a diagram showing the absorption spectrum of a coating film of a stator core measured by Fourier transform infrared spectroscopy. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. However, the embodiment described below is subject to various technically preferable limitations for carrying out the present invention, but the scope of the present invention is not limited to the following embodiment and illustrated examples.

[0010] ==First embodiment== Fig. 1 is a perspective view showing the configuration of a hard disk drive 1. Fig. 2 is a partial cross-sectional view showing an example of a spindle motor 3 used in the hard disk drive 1.

[0011] 2 and other figures, the direction parallel to the central axis of shaft 70 (described later) is defined as the axial direction, the direction around the central axis of shaft 70 is defined as the circumferential direction, and the direction perpendicular to the axial direction is defined as the radial direction. For the sake of explanation, the axial direction is defined as the up-down direction, and the rotating part 20 side relative to stationary part 10 is defined as the top, and the stationary part 10 side is defined as the bottom.

[0012] <Hard disk drive> The hard disk drive device 1 includes a housing 2 , a spindle motor 3 , a recording disk 4 , and a bearing device 5 .

[0013] The housing 2 includes a case 6 and a cover 7. The case 6 has a box-like shape that is substantially rectangular and has one side open and a bottom. The cover 7 is a plate-like member that closes the open side of the case 6. The cover 7 is fastened to the case 6 using screws 7A. A sealing means (not shown) is provided between the case 6 and the cover 7, so that the cover 7, together with the case 6, forms the housing 2 having a sealed internal space S.

[0014] The internal space S of the housing 2 is filled with air or helium gas, which has a lower density than air. Note that the internal space S may be filled with, for example, nitrogen gas or a mixed gas of helium and nitrogen, in addition to air or helium gas. The internal space S accommodates a spindle motor 3, a recording disk 4, and a bearing device 5.

[0015] The spindle motor 3 (an example of a motor) rotatably supports a plurality of recording disks 4. The detailed structure of the spindle motor 3 will be described later.

[0016] A plurality of recording disks 4 are provided and supported by the spindle motor 3 so that their disk surfaces face each other. A gap is formed between each of the recording disks 4.

[0017] The bearing device 5 swingably supports a plurality of swing arms 8 that are disposed in the gaps between the respective recording disks 4.

[0018] The swing arm 8 has a magnetic head 9 at its tip. The magnetic head 9 applies magnetism to the recording disk 4 and also reads magnetism from the recording disk 4. When the swing arm 8 swings, the magnetic head 9 moves above the recording disk 4.

[0019] When the spindle motor 3 rotates, the recording disk 4 also rotates. In this state, when the swing arm 8 swings, the magnetic head 9 moves over the rotating recording disk 4. The magnetic head 9 then applies magnetism to the recording disk 4, and records data on the recording disk 4. The magnetic head 9 also reads magnetism from the recording disk 4, and reads out the data stored on the recording disk 4.

[0020] As a recording method for the hard disk drive 1, a thermally assisted magnetic recording (HAMR) method may be adopted.

[0021] <Spindle motor> Next, a detailed configuration of the spindle motor 3 will be described. Fig. 2 is a partial cross-sectional view showing the configuration of the spindle motor 3. The spindle motor 3 includes a stationary part 10 and a rotating part 20 that rotates relative to the stationary part 10 via a bearing mechanism.

[0022] (Stationary part) The stationary portion 10 includes a base plate 30 , a bearing sleeve 40 , a stator core 50 , and a magnetic attraction plate 60 .

[0023] The base plate 30 is a metal member. The base plate 30 is not limited to being made of metal, and may be made of, for example, resin. The base plate 30 is formed with a through hole 31, a circumferential groove portion 32, a circumferential wall portion 33, and a plate recess 34.

[0024] The through hole 31 is a hole for fixing the bearing sleeve 40. The through hole 31 is provided so as to penetrate the base plate 30 in the axial direction. The through hole 31 is cylindrical, and the inner diameter of the cylinder is approximately the same as or larger than the outer diameter of the bearing sleeve 40.

[0025] The circumferential groove portion 32 is formed radially outward of the through hole 31. The circumferential groove portion 32 is an annular groove provided so as to be coaxial with the central axis of the through hole 31 when viewed in the axial direction.

[0026] The circumferential wall portion 33 is formed radially outward of the through hole 31 and inward of the circumferential groove portion 32. The circumferential wall portion 33 is an annular wall provided so as to be coaxial with the central axis of the through hole 31 when viewed in the axial direction, and protrudes upward in the axial direction.

[0027] The plate recess 34 is formed on the radially inner side of the circumferential wall portion 33. The plate recess 34 is a cylindrical space provided so as to be coaxial with the central axis of the through hole 31 when viewed in the axial direction, and opens upward. The diameter of the plate recess 34 is larger than the outer diameter of the through hole 31. The plate recess 34 is connected to the upper side of the through hole 31 in the axial direction.

[0028] The bearing sleeve 40 rotatably supports the shaft 70. The bearing sleeve 40 is a cylindrical iron member made of stainless steel or the like that extends in the axial direction. The bearing sleeve 40 is inserted into the through hole 31 (see FIG. 2). The bearing sleeve 40 is fixed to the through hole 31 by an adhesive that is applied to one or both of the outer circumferential surface of the bearing sleeve 40 and the inner circumferential surface of the through hole 31. Note that the bearing sleeve 40 is not limited to being made of iron, and may be a metal member made of aluminum, brass, or the like. The bearing sleeve 40 is provided with a radial dynamic pressure generating groove 41 and a thrust dynamic pressure generating groove 42.

[0029] The radial dynamic pressure generating grooves 41 are provided on the inner circumferential surface 40a of the bearing sleeve 40. In this embodiment, the radial dynamic pressure generating grooves 41 are formed in a continuous row in the circumferential direction on the inner circumferential surface 40a, and are formed in two rows spaced apart in the axial direction.

[0030] The thrust dynamic pressure generating groove 42 is provided in an end face 44 of the axially upper sleeve end 43a of the bearing sleeve 40. The thrust dynamic pressure generating groove 42 is provided in an annular shape so as to be coaxial with the central axis of the bearing sleeve 40 when viewed in the axial direction.

[0031] A large diameter recess 45 and a small diameter recess 46 are formed continuously in the axial direction at the axially lower sleeve end 43b of the bearing sleeve 40. A counter plate 47 is attached to the large diameter recess 45.

[0032] The large diameter recess 45 is formed in the sleeve end portion 43b. The large diameter recess 45 is a cylindrical space provided so as to be coaxial with the central axis of the through hole 31 when viewed in the axial direction. The large diameter recess 45 opens downward.

[0033] The small diameter recess 46 is formed above the large diameter recess 45 at the sleeve end 43b. The small diameter recess 46 is a cylindrical space provided so as to be coaxial with the central axis of the through hole 31 when viewed in the axial direction. The small diameter recess 46 is connected to the large diameter recess 45 in the axial direction. The diameter of the small diameter recess 46 is smaller than the diameter of the large diameter recess 45. By forming the small diameter recess 46 at the sleeve end 43b, the bearing sleeve 40 is formed with an annular surface 48 that is annular when viewed in the axial direction, and an inner peripheral side surface 49 in the circumferential direction.

[0034] The counter plate 47 is a disk-shaped cover that is inserted into the large diameter recess 45 from below the sleeve end 43b. The counter plate 47 covers the large diameter recess 45 and the small diameter recess 46. The counter plate 47 is a member made of iron such as stainless steel. The outer diameter of the counter plate 47 is approximately equal to the inner diameter of the large diameter recess 45. The axial thickness of the counter plate 47 is approximately equal to the depth of the large diameter recess 45. Note that the counter plate 47 is not limited to being made of iron, and may be a metal member such as aluminum or brass.

[0035] When the counter plate 47 is inserted into the large diameter recess 45, the outer edge of the counter plate 47 and the inner edge of the large diameter recess 45 are joined by laser welding. In this way, the counter plate 47 is fixed to the bearing sleeve 40 without any gaps, and closes the large diameter recess 45 and the small diameter recess 46.

[0036] The stator core 50 is a member in which a plurality of annular electromagnetic steel plates are laminated in the axial direction when viewed in the axial direction. The stator core 50 is disposed inside the circumferential groove portion 32 and fixed by a method such as adhesion. The surface of the stator core 50 is covered with a coating film 53. As shown in FIG. 3, the stator core 50 has a plurality of pole teeth (salient poles) that extend radially outward and are disposed along the circumferential direction. Coils 51 are wound around the pole teeth. The stator core 50 generates magnetic flux when a current flows through the coils 51. A manufacturing method for the stator core 50 will be described later.

[0037] The magnetic attraction plate 60 is a member that stabilizes the rotation of the rotor hub 80, which will be described later. The magnetic attraction plate 60 is made of, for example, a magnetic material. The magnetic attraction plate 60 generates a magnetic flux in response to a current applied to the coil 51. The magnetic attraction plate 60 is installed radially outward of the stator core 50 in the circumferential groove portion 32.

[0038] (Rotating part) The rotating part 20 has a shaft 70 , a rotor hub 80 , and a rotor magnet 90 .

[0039] The shaft 70 is a member that serves as a rotating shaft of the spindle motor 3. The shaft 70 is rotatably supported inside the bearing sleeve 40. The shaft 70 has a columnar shaft portion 71 and a flange portion 72. In the shaft 70, the shaft portion 71 and the flange portion 72 are integral with each other.

[0040] The shaft portion 71 is a cylindrical shaft member. The shaft portion 71 has a flange portion 72 integrally formed with a lower shaft end portion 73. The shaft portion 71 is disposed inside the bearing sleeve 40 so that the shaft end portion 73 with the flange portion 72 is on the lower side. That is, the outer peripheral surface of the shaft portion 71 is surrounded by the inner peripheral surface 40a of the bearing sleeve 40. The outer peripheral surface of the shaft portion 71 and the inner peripheral surface 40a of the bearing sleeve 40 face each other with a small gap therebetween. Note that the radial dynamic pressure generating grooves 41 may be formed on the outer peripheral surface of the shaft portion 71 instead of the inner peripheral surface 40a of the bearing sleeve 40.

[0041] The flange portion 72 is an annular flange member that expands in the radial direction when viewed in the axial direction. The flange portion 72 is joined to a shaft end portion 73 and is integral with the shaft portion 71. The outer diameter of the flange portion 72 is smaller than the inner diameter of the small diameter recess 46. Thrust dynamic pressure generating grooves 74 are formed on the upper and lower surfaces of the flange portion 72.

[0042] The thrust dynamic pressure generating groove 74 is provided on the upper and lower surfaces of the flange portion 72. The thrust dynamic pressure generating groove 74 is provided in an annular shape so as to be coaxial with the central axis of the flange portion 72 when viewed in the axial direction.

[0043] The flange portion 72 is disposed in the small diameter recess 46 when the shaft 70 is supported by the bearing sleeve 40. The upper surface of the flange portion 72 faces the annular surface 48 formed in the bearing sleeve 40 by the small diameter recess 46 across a small gap. The lower surface of the flange portion 72 faces the upper surface of the counter plate 47 across a small gap. The side surface of the flange portion 72 faces the inner circumferential side surface 49 across a small gap. By disposing the flange portion 72 between the annular surface 48 and the counter plate 47, axial movement of the flange portion 72 and the shaft 70 is prevented.

[0044] Lubricating oil is filled between the shaft 70 and the bearing sleeve 40. Specifically, the lubricating oil is filled between the outer peripheral surface of the shaft portion 71 and the inner peripheral surface 40a of the bearing sleeve 40, between the upper surface of the flange portion 72 and the annular surface 48, between the lower surface of the flange portion 72 and the upper surface of the counter plate 47, and between the side surface of the flange portion 72 and the inner peripheral side surface 49.

[0045] The rotor hub 80 is a member that rotates together with the shaft 70. The rotor hub 80 is attached to the upper end of the shaft 70 and is connected to the shaft 70. The rotor hub 80 has a disk portion 81, a first cylindrical portion 82, a second cylindrical portion 83, and an outer edge portion 84.

[0046] The disk portion 81 is a disk-shaped member that is coaxial with the central axis of the shaft 70 when viewed in the axial direction. The disk portion 81 has a rotor hub through hole 85. The rotor hub through hole 85 is provided at the center of the disk portion 81 when viewed in the axial direction. The disk portion 81 is fixed to the shaft 70. Specifically, the upper end of the shaft 70 is inserted into the rotor hub through hole 85 and fixed by a method such as press fitting or adhesive, thereby fixing the disk portion 81 to the shaft 70. When the shaft 70 is supported by the bearing sleeve 40, the disk portion 81 faces the end face 44 of the bearing sleeve 40 with a small gap therebetween.

[0047] The first cylindrical portion 82 is a cylindrical member having a thickness in the radial direction. The first cylindrical portion 82 is provided so as to be coaxial with the central axis of the rotor hub through hole 85 when viewed in the axial direction, and protrudes axially downward. The inner diameter of the first cylindrical portion 82 is larger than the outer diameter of the bearing sleeve 40. The inner circumferential surface of the first cylindrical portion 82 faces the outer circumferential surface of the bearing sleeve 40 with a gap therebetween. The outer diameter of the first cylindrical portion 82 is smaller than the inner diameter of the circumferential wall portion 33. The outer circumferential surface of the first cylindrical portion 82 faces the inner circumferential surface of the circumferential wall portion 33 with a gap therebetween.

[0048] The second cylindrical portion 83 is a cylindrical member having a thickness in the radial direction. The second cylindrical portion 83 is provided so as to be coaxial with the center axis of the rotor hub through hole 85 when viewed in the axial direction, and protrudes axially downward. The second cylindrical portion 83 is provided on the outer edge of the disk portion 81.

[0049] The outer edge portion 84 is an annular member. The outer edge portion 84 is provided at the lower end of the second cylindrical portion 83. The outer edge portion 84 protrudes radially outward from the second cylindrical portion 83 and is formed in a flange shape. A plurality of recording disks 4 are installed above the outer edge portion 84 and radially outward from the second cylindrical portion 83 (see FIG. 1).

[0050] Lubricating oil is filled between the rotor hub 80 and the bearing sleeve 40. Specifically, the lubricating oil is filled between the lower surface of the disk portion 81 axially inward of the first cylindrical portion 82 and the end surface 44 of the sleeve end 43a on the axially upper side of the bearing sleeve 40.

[0051] The rotor magnet 90 is an annular member having a magnetic pole structure magnetized with polarities inverted as N, S, N, S... along the circumferential direction when viewed in the axial direction. In this embodiment, the rotor magnet 90 is attached to the inner circumferential surface of the second cylindrical portion 83. The rotor magnet 90 is located at approximately the same position as the stator core 50 in the axial direction, and at approximately the same position as the magnetic attraction plate 60 in the radial direction.

[0052] The above describes the structure of the spindle motor 3. Note that the above description is an example of the motor structure. Therefore, the motor structure is not limited to the above structure, and may be another structure.

[0053] <Spindle motor operation> When the coil 51 is energized, a magnetic attraction force and a magnetic repulsion force are generated between the magnetic poles of the rotor magnet 90 and the pole teeth of the stator core 50. As a result, the rotating part 20 rotates relative to the stationary part 10 with the shaft 70 as the rotation axis.

[0054] The shaft 70 rotates relative to the bearing sleeve 40. At this time, dynamic pressure is generated in the lubricating oil as the lubricating oil is pressurized by the radial dynamic pressure generating grooves 41 and the thrust dynamic pressure generating grooves 74. The generated dynamic pressure supports the shaft 70 in a non-contact state relative to the bearing sleeve 40 in the radial and axial directions.

[0055] As the shaft 70 rotates, the rotor hub 80 rotates relative to the bearing sleeve 40. At this time, the lubricating oil is pressurized by the thrust dynamic pressure generating grooves 42, generating dynamic pressure in the lubricating oil. The generated dynamic pressure supports the rotor hub 80 relative to the bearing sleeve 40 in a non-contact state in the axial direction.

[0056] <Manufacturing method of stator core> Next, a description will be given of a manufacturing method of the stator core 50. The manufacturing method of the stator core 50 includes a film forming / heating step and a fixing step.

[0057] First, the film forming and heating process will be described. The stator core 50 is formed by applying an electrochemical coating to the surface of a laminate of electromagnetic steel sheets. First, a plate-shaped electromagnetic steel sheet is punched out by a press or the like, and is formed into a shape having annular and radial pole teeth when viewed in the axial direction as shown in FIG. 3. Next, the formed electromagnetic steel sheets 52 are stacked in the axial direction to form a laminate of electromagnetic steel sheets 52. The laminate of electromagnetic steel sheets 52 is joined by crimping or laser welding adjacent electromagnetic steel sheets 52 vertically. In other words, the stacked electromagnetic steel sheets 52 are integrated to form a laminate.

[0058] Next, electrodeposition coating is performed on the laminate of the electromagnetic steel sheets 52. Electrodeposition coating is a process in which a member to be coated is immersed in a tank filled with paint, and an electric current is passed through the paint to attach the paint to the surface of the member to be coated, and then the paint is dried and thermally cured. The paint may contain pigments such as coloring pigments, extender pigments, and rust-preventive pigments. As coloring pigments, for example, carbon black, acetylene black, graphite, iron black, aniline black, etc. are used as black pigments, and titanium white, zinc white, lithopone, zinc sulfide, antimony white, etc. are used as white pigments. As extender pigments, for example, clay, mica, baryta, kaolin, talc, calcium carbonate, silica, barium sulfate, alumina white, aluminum silicate, etc. are used. As rust-preventive pigments, for example, aluminum phosphomolybdate, aluminum dihydrogen tripolyphosphate, zinc white, etc. are used. In this embodiment, the paint uses a coating film-forming material that contains a benzene ring-containing epoxy resin and a pigment containing an aluminum silicate component. In addition, the paint used may contain an epoxy-polyamide resin.

[0059] In order to perform electrodeposition coating on the laminate of electromagnetic steel sheets 52, the laminate of electromagnetic steel sheets 52 is immersed in a tank filled with paint and an electric current is applied. Then, when the laminate of electromagnetic steel sheets 52 is pulled out of the tank, the paint adheres to the surfaces of the laminate of electromagnetic steel sheets 52.

[0060] Next, the laminate of the electromagnetic steel sheets 52 with the paint applied to the surface is heated to heat-harden the paint. Here, the laminate of the electromagnetic steel sheets 52 with the paint applied to the surface is usually heated at a temperature of about 200°C to 220°C for about 10 to 60 minutes, but in this embodiment, it is heated at a temperature of 280°C for about 10 to 60 minutes. The heating temperature is preferably 250°C or higher because the heating time can be shortened. In this way, when heat-hardening the paint, setting the heating temperature high without changing the heating time, or setting the heating time long without changing the heating temperature to promote the heat hardening of the paint more than usual is called overbaking. In other words, the coating film 53, which is an overbaked epoxy resin-containing electrodeposition coating film, is formed on the surface of the laminate of the electromagnetic steel sheets 52. In this way, the stator core 50 is manufactured.

[0061] Next, the fixing process will be described. First, adhesive is applied to the inner peripheral surface and the inner edge of the lower surface of the stator core 50 manufactured in the film forming and coating process. Then, the stator core 50 is inserted into the inside of the circumferential groove portion 32 from above the base plate 30 so that the axial center of the stator core 50 and the axial center of the through hole 31 are aligned, and fixed. In this manner, the stator core 50 is fixed to the base plate 30.

[0062] Here, overbaking will be explained. Overbaking is a method of baking a coating material by supplying energy higher than the energy required to bring the crosslinks (bonds) existing between the molecules that make up the coating film to the desired state (i.e., curing). Overbaking is caused by excessive heating time, excessive heating temperature, or both excessive heating time and excessive heating temperature.

[0063] Overbaking a coating film containing a resin or the like may result in more crosslinks being formed than with regular baking. Overbaking forms more crosslinks and reduces the number of sites where crosslinks can be formed, which is thought to result in suppressed incorporation of oxygen atoms that contribute to crosslink formation in the overbaked coating film containing a resin or the like. In addition, the formation of crosslinks by overbaking is thought to lead to an increase in the hardness of the overbaked coating film containing a resin or the like.

[0064] Moreover, overbaking may once again rupture (cut) the crosslinks (bonds) that existed between the molecules that make up the coating film. Depending on the location of the severance of these bonds, the coating film's light absorption wavelength and the amount of light absorbed may change. As a result, it is believed that the absorption spectrum of the coating film after overbaking will change compared to the coating film before overbaking.

[0065] In the above-described stator core 50, the coating film 53 preferably has a pencil hardness of 5H or more. The pencil hardness is measured in accordance with JIS K5600.

[0066] Furthermore, when the coating film 53 has an absorption spectrum measured by Fourier infrared spectrometry, it is preferable that the peak intensity ratio x calculated from the obtained absorption spectrum using the following formula (1) is 0.8 or less, more preferably 0.6 or less. x=I polymer / I pigment (1)

[0067] Here, I polymer is the peak intensity value of the wavenumber corresponding to the absorbance due to the resin benzene ring, I pigment represents the value of the peak intensity at the wavenumber corresponding to the absorbance derived from the pigment containing an aluminum silicate component.

[0068] I polymer For example, when an epoxy resin containing a benzene ring is used as the resin, the wave number is 1490 cm -1 ~1520cm -1 The peak intensity in the vicinity of Ipigment For example, when a pigment containing aluminum silicate is used as the pigment, the wave number is 995 cm -1 ~1010cm -1 The peak intensity in the vicinity can be used.

[0069] The absorption spectrum is measured directly by the Attenuated Total Reflection (ATR) method using a diamond crystal (prism) to measure the infrared (IR) absorption spectrum of the coating film 53 formed on the surface of the stator core 50. In the ATR method, the shape of the spectrum changes due to the difference in refractive index between the sample and the prism, and it is common to perform ATR correction, especially when comparing with data measured by the transmission method. In addition, in measurements using infrared spectroscopy (IR method), it is common to perform background (no sample) measurement immediately before sample measurement to eliminate the influence of the background due to the atmosphere.

[0070] The method for manufacturing the stator core 50 may include a film-forming / first heating step, a second heating step, and a fixing step, instead of the above-mentioned manufacturing method.

[0071] First, the film-forming and first heating step will be described. The step of laminating a plurality of magnetic steel sheets 52 in the axial direction to form an integrated laminate is the same as that described in the film-forming and heating step described above, and therefore the description thereof will be omitted.

[0072] Next, electrodeposition coating is performed on the laminate of the electromagnetic steel sheets 52. The paint used is a coating film forming material that contains a benzene ring-containing epoxy resin and a pigment that contains an aluminum silicate component. Note that the paint may also be one that contains an epoxy-polyamide resin.

[0073] In order to perform electrodeposition coating on the laminate of electromagnetic steel sheets 52, the laminate of electromagnetic steel sheets 52 is immersed in a tank filled with paint and an electric current is applied. Then, when the laminate of electromagnetic steel sheets 52 is pulled out of the tank, the paint adheres to the surfaces of the laminate of electromagnetic steel sheets 52.

[0074] Next, the laminate of electromagnetic steel sheets 52 with the paint attached to its surface is heated to heat and harden the paint. In this process, the heating temperature and heating time conditions need only be such that the applied paint hardens, and can be appropriately selected depending on the type of paint. For example, the laminate of electromagnetic steel sheets 52 with the paint attached to its surface is heated at a temperature of about 200°C to 220°C for about 10 to 60 minutes. As a result, the paint attached to the surface of the laminate of electromagnetic steel sheets 52 hardens to become a coating film.

[0075] Next, the second heating step will be described. The second heating step is an over-baking step in which the coating film is heated at a higher temperature than in the coating / first heating step. In the second heating step, the laminate of the electromagnetic steel sheets 52 coated with the coating film produced in the above-mentioned coating / first heating step is heated at an even higher temperature. For example, the laminate of the electromagnetic steel sheets 52 coated with the coating film is heated at a temperature of 280° C. for about 10 to 60 minutes. The heating temperature in the second heating step is preferably 250° C. or higher since the heating time can be shortened. However, depending on the constituent material of the coating film, caution is required since the coating film may be thermally decomposed when heated at a specific temperature or higher (300° C. in the case of a coating film containing an epoxy resin). As a result, a coating film 53, which is an over-baked epoxy resin-containing electrodeposition coating film, is formed on the surface of the laminate of the electromagnetic steel sheets 52. In this manner, the stator core 50 is produced.

[0076] Finally, the fixing step will be described. The fixing step is a step of fixing the stator core 50 manufactured in the second heating step to the base plate 30. The method of fixing the stator core 50 is the same as the fixing step described above, and therefore the description will be omitted.

[0077] ==Second embodiment== Next, a blower 300 according to a second embodiment will be described with reference to Figs. 5 to 7. Fig. 5 is a perspective view of the blower 300. The blower 300 is a centrifugal blower. Note that the blower 300 is not limited to a centrifugal blower, and may be, for example, an axial flow blower or a mixed flow blower. The blower 300 includes a casing 310, a motor 320, and an impeller 330.

[0078] 7 and other figures, the direction parallel to the central axis of shaft 380 of motor 320 (described later) is defined as the axial direction, the direction around the central axis of shaft 380 is defined as the circumferential direction, and the direction perpendicular to the axial direction is defined as the radial direction. For the sake of explanation, the axial direction is defined as the up-down direction, and the side of base plate 340 (described later) is defined as the bottom, and the side of lid 350 is defined as the top.

[0079] <Casing> The casing 310 is a housing that houses the motor 320 and the impeller 330. The casing 310 is configured by combining a base plate 340 and a lid 350. The casing 310 has an intake port 311 and an exhaust port 312. In this embodiment, the intake port 311 is provided in the lid 350. The exhaust port 312 is provided on a side surface of the casing 310 and faces radially outward.

[0080] The base plate 340 is a metal member. The motor 320 is disposed on the base plate 340. The structure of the base plate 340 will be described together with the structure of the motor 320.

[0081] The lid 350 is a member that, together with the base plate 340, forms the internal space of the casing 310. The lid 350 has a flat plate portion 351 and a side wall portion 352.

[0082] Flat plate portion 351 is a plate-shaped member. Flat plate portion 351 faces base plate 340 when base plate 340 and lid 350 are combined. Flat plate portion 351 has suction port 311. Suction port 311 is a hole that penetrates flat plate portion 351 in the axial direction. The diameter of suction port 311 is larger than the diameter of rotor hub 390 of motor 320, which will be described later.

[0083] Side wall portion 352 is a portion extending in the axial direction from the edge of flat plate portion 351. Side wall portion 352 is discontinued at a portion of the edge of flat plate portion 351. Therefore, when base plate 340 and lid 350 are combined, a portion where side wall portion 352 is not formed becomes an opening. This opening is air outlet 312.

[0084] <Motor> Fig. 6 is a perspective view of blower 300 with lid 350 removed, and Fig. 7 is a cross-sectional view of a plane including the central axis of shaft 380. Motor 320 has stationary portion 321 and rotating portion 322.

[0085] (Stationary part) The stationary portion 321 includes a base plate 340 , a bearing sleeve 360 ​​, and a stator core 370 .

[0086] The base plate 340 has a through hole 341 , a circumferential wall portion 342 , and a recess 343 .

[0087] The through hole 341 is a hole for fixing the bearing sleeve 360. The through hole 341 is provided so as to penetrate the base plate 340 in the axial direction. The through hole 341 is cylindrical, and the inner diameter of the cylinder is approximately the same as or larger than the outer diameter of the bearing sleeve 360.

[0088] The circumferential wall portion 342 is formed radially outward of the through hole 341. The circumferential wall portion 342 is an annular wall provided so as to be coaxial with the central axis of the through hole 341 when viewed in the axial direction, and protrudes upward in the axial direction.

[0089] The recess 343 is formed on the radially inner side of the circumferential wall portion 342. The recess 343 is a cylindrical space provided so as to be coaxial with the central axis of the through hole 341 when viewed in the axial direction, and opens upward. The diameter of the recess 343 is larger than the outer diameter of the through hole 341. The recess 343 is connected to the upper side of the through hole 341 in the axial direction.

[0090] The bearing sleeve 360 ​​rotatably supports the shaft 380. The bearing sleeve 360 ​​is a cylindrical iron member extending in the axial direction. The bearing sleeve 360 ​​is inserted into the through hole 341 (see FIG. 7). The bearing sleeve 360 ​​is fixed to the through hole 341 by an adhesive applied to one or both of the outer circumferential surface of the bearing sleeve 360 ​​and the inner circumferential surface of the through hole 341. Note that the bearing sleeve 360 ​​is not limited to an iron member such as stainless steel, and may be made of resin, for example. The bearing sleeve 360 ​​is provided with a radial dynamic pressure generating groove 361 and a thrust dynamic pressure generating groove 362.

[0091] The radial dynamic pressure generating grooves 361 are provided on the inner circumferential surface of the bearing sleeve 360. In this embodiment, the radial dynamic pressure generating grooves 361 are formed in a continuous row in the circumferential direction on the inner circumferential surface, and are formed in two rows spaced apart in the axial direction.

[0092] The thrust dynamic pressure generating groove 362 is provided in an end face 364 of an axially upper sleeve end 363 of the bearing sleeve 360. The thrust dynamic pressure generating groove 362 is provided in an annular shape so as to be coaxial with the central axis of the bearing sleeve 360 ​​when viewed in the axial direction.

[0093] The stator core 370 is a member in which a plurality of annular electromagnetic steel plates are laminated in the axial direction when viewed in the axial direction. The stator core 370 is disposed radially outward of the circumferential wall portion 342 and fixed by a method such as adhesion. The surface of the stator core 370 is covered with a coating film 373. The stator core 370 has a plurality of pole teeth (salient poles) that extend radially outward and are disposed along the circumferential direction. A coil 371 is wound around the pole teeth. The stator core 370 generates a magnetic flux when a current flows through the coil 371. The manufacturing method of the stator core 370 is the same as that of the stator core 50 of the first embodiment, and therefore a description thereof will be omitted.

[0094] (Rotating part) The rotating portion 322 includes a shaft 380 , a rotor hub 390 , and a rotor magnet 400 .

[0095] Shaft 380 is a member that serves as a rotating shaft of motor 320. Shaft 380 is a cylindrical shaft member. Shaft 380 is disposed inside bearing sleeve 360 ​​and supported rotatably. The outer circumferential surface of shaft 380 and the inner circumferential surface of bearing sleeve 360 ​​face each other with a small gap therebetween. Note that radial dynamic pressure generating grooves 361 may be formed on the outer circumferential surface of shaft 380 instead of the inner circumferential surface of bearing sleeve 360.

[0096] Lubricating oil is filled between the shaft 380 and the bearing sleeve 360. Specifically, the lubricating oil is filled between the outer circumferential surface of the shaft 380 and the inner circumferential surface of the bearing sleeve 360.

[0097] Rotor hub 390 is a member that rotates together with shaft 380. Rotor hub 390 is attached to the upper end of shaft 380 and connected to shaft 380. Rotor hub 390 has a disk portion 391, a first cylindrical portion 392, a second cylindrical portion 393, and an outer edge portion 394.

[0098] The disk portion 391 is a disk-shaped member that is coaxial with the central axis of the shaft 380 when viewed in the axial direction. The disk portion 391 has a rotor hub through hole 395. The rotor hub through hole 395 is provided at the center of the disk portion 391 when viewed in the axial direction. The disk portion 391 is fixed to the shaft 380. Specifically, the upper end of the shaft 380 is inserted into the rotor hub through hole 395, and the disk portion 391 is fixed to the shaft 380 by a method such as press-fitting or adhesion. When the shaft 380 is supported by the bearing sleeve 360, the disk portion 391 faces an end surface 364 of the bearing sleeve 360 ​​with a small gap therebetween.

[0099] The first cylindrical portion 392 is a cylindrical member having a thickness in the radial direction. The first cylindrical portion 392 is provided so as to be coaxial with the central axis of the rotor hub through hole 395 when viewed in the axial direction, and protrudes axially downward. The inner diameter of the first cylindrical portion 392 is larger than the outer diameter of the bearing sleeve 360. The inner circumferential surface of the first cylindrical portion 392 faces the outer circumferential surface of the bearing sleeve 360 ​​with a gap therebetween. The outer diameter of the first cylindrical portion 392 is smaller than the inner diameter of the circumferential wall portion 342. The outer circumferential surface of the first cylindrical portion 392 faces the inner circumferential surface of the circumferential wall portion 342 with a gap therebetween.

[0100] The second cylindrical portion 393 is a cylindrical member having a thickness in the radial direction. The second cylindrical portion 393 is provided so as to be coaxial with the center axis of the rotor hub through hole 395 when viewed in the axial direction, and protrudes downward in the axial direction. The second cylindrical portion 393 is provided on the outer edge of the disc portion 391.

[0101] The outer edge portion 394 is an annular member. The outer edge portion 394 is provided at the lower end of the second cylindrical portion 393. The outer edge portion 394 protrudes radially outward from the second cylindrical portion 393 and is formed in a flange shape. The impeller 330 is installed above the outer edge portion 394 and radially outward from the second cylindrical portion 393 (see FIGS. 6 and 7).

[0102] Lubricating oil is filled between the rotor hub 390 and the bearing sleeve 360. Specifically, the lubricating oil is filled between the lower surface of the disk portion 391 axially inward of the first cylindrical portion 392 and an end surface 364 of the sleeve end portion 363 axially upper of the bearing sleeve 360.

[0103] The rotor magnet 400 is an annular member having a magnetic pole structure magnetized in a state where polarity is inverted along the circumferential direction as N, S, N, S... when viewed in the axial direction. In this embodiment, the rotor magnet 400 is attached to the inner circumferential surface of the second cylindrical portion 393.

[0104] The above describes the structure of the motor 320. Note that the above description is an example of the motor structure. Therefore, the motor structure is not limited to the above structure, and may be another structure.

[0105] <Motor operation> When the coil 371 is energized, a magnetic attraction force and a magnetic repulsion force are generated between the magnetic poles of the rotor magnet 400 and the pole teeth of the stator core 370. As a result, the rotating part 322 rotates relative to the stationary part 321 with the shaft 380 as the rotation axis.

[0106] The shaft 380 rotates relative to the bearing sleeve 360. At this time, dynamic pressure is generated in the lubricating oil as the lubricating oil is pressurized by the radial dynamic pressure generating grooves 361. The generated dynamic pressure supports the shaft 380 in a non-contact state relative to the bearing sleeve 360 ​​in the radial and axial directions.

[0107] As shaft 380 rotates, rotor hub 390 rotates relative to bearing sleeve 360. At this time, dynamic pressure is generated in the lubricating oil as the lubricating oil is pressurized by thrust dynamic pressure generating grooves 362. Due to the generated dynamic pressure, rotor hub 390 is supported in a non-contact state in the axial direction relative to bearing sleeve 360.

[0108] <Impeller> The impeller 330 generates a radially outward airflow by rotating. The impeller 330 is fixed to the motor 320. The impeller 330 has a ring portion 331 and a plurality of blades 332.

[0109] The ring portion 331 is an annular component and is fixed above an outer edge portion 394 of the rotor hub 390 and to the outside in the radial direction of the second cylindrical portion 393 by a method such as press-fitting or adhesion.

[0110] The blades 332 are members extending radially outward from the ring portion 331. A plurality of the blades 332 are provided on the ring portion 331 at intervals in the circumferential direction.

[0111] <Blower operation> In the blower 300 having the above configuration, when the motor 320 rotates, the impeller 330 rotates. When the impeller 330 rotates, air is sucked in through the suction port 311 and guided into the internal space of the casing 310. The air sucked into the internal space is blown out from the radial inside to the outside of the internal space by the action of the multiple blades 332. The blown out air is then blown out of the internal space of the casing 310 through the blowout port 312.

[0112] <Effects> The spindle motor 3 or motor 320 according to the above embodiment includes a stator core 50 in which the surface of a laminate of electromagnetic steel sheets 52 is covered with a coating film 53, and the coating film 53 is an overbaked epoxy resin-containing electrodeposition coating film.

[0113] According to the above spindle motor 3 or motor 320, the surface of the stator core 50 is covered with the coating film 53 of the overbaked epoxy resin-containing electrodeposition coating film, so that the surface of the stator core 50 is covered with a coating film that is harder than a coating film that is not overbaked. Therefore, even if pressure is applied to the coil 51 in the process of winding the coil 51 around the stator core 50, the coil 51 is less likely to sink into the coating film 53 of the stator core 50.

[0114] In addition, because the coil 51 is less likely to sink into the coating film 53 of the stator core 50, winding defects are less likely to occur in the process of winding the coil 51 around the stator core 50. Therefore, the defect rate in the process of winding the coil 51 around the stator core 50 is improved.

[0115] In the spindle motor 3 or the motor 320 according to the above embodiment, the coating film 53 of the stator core 50 has a pencil hardness of 5H or more.

[0116] The hardness of the coating of a stator core that has not been overbaked is approximately 3H to 4H in pencil hardness. On the other hand, according to the above spindle motor 3 or motor 320, the hardness of coating 53 of stator core 50 is 5H or more in pencil hardness. Therefore, in the process of winding coil 51 around stator core 50, coil 51 is less likely to sink into coating 53 of stator core 50.

[0117] In the spindle motor 3 or the motor 320 according to the above embodiment, the coating film 53 of the stator core 50 contains a benzene ring-containing epoxy resin and a pigment containing an aluminum silicate component, and in an absorption spectrum obtained by Fourier infrared spectroscopy measurement of the coating film 53, a peak intensity ratio x calculated using the following formula (1): x=I polymer / I pigment (1) The value of is less than or equal to 0.8.

[0118] According to the above-described spindle motor 3 or motor 320, in the absorption spectrum obtained by Fourier infrared spectroscopy measurement of the coating film 53 of the stator core 50, the peak intensity ratio calculated using equation (1) is 0.8 or less, so that it is possible to inspect by non-destructive testing whether the overbaked coating film 53 has the desired hardness.

[0119] The hard disk drive device 1 according to the first embodiment also includes a spindle motor 3.

[0120] According to the above hard disk drive 1, since it includes the spindle motor 3, the defect rate in the process of winding the coil 51 around the stator core 50 is improved. Therefore, the defect rate of the hard disk drive 1 is also improved.

[0121] Moreover, the magnetic recording method used in the hard disk drive 1 according to the first embodiment is a thermally assisted magnetic recording method.

[0122] In hard disk drives that use the thermally assisted magnetic recording (HAMR) method, the temperature at the tip of the magnetic head can reach as high as 400° C. In such hard disk drives, it is known that it is useful to have oxygen present within the hard disk drive in order to decompose organic impurities that may be a cause of read / write errors.

[0123] The present inventors have investigated the possibility that in a high-temperature environment of 400°C, not only organic impurities are decomposed, but also other organic compounds present in the hard disk drive are oxidized and consume oxygen, resulting in insufficient decomposition of organic impurities by oxygen. Therefore, the present inventors have focused on the coating (coating) of the stator core as one candidate for other organic compounds that consume oxygen, and have reconsidered the configuration of the coating based on the idea that the coating of the stator core does not consume oxygen (prevention of oxygen intake). As a mode of chemically changing the structure of the coating, the inventors have come to the possibility that the mode of an overbaked electrodeposition coating film can realize this idea. At this time, the inventors have come to the idea that the coating film has a pencil hardness of a predetermined value or more, and that when the coating film is subjected to Fourier infrared spectroscopy, the ratio of the peak intensity derived from the resin contained in the coating film to the peak intensity derived from the pigment is within a specific range.

[0124] According to the above hard disk drive 1, a thermally assisted magnetic recording method is adopted as the magnetic recording method, and the coating film 53 of the stator core 50 of the spindle motor 3 is overbaked. Therefore, the amount of oxygen remaining inside the hard disk drive 1 that is taken in by the coating film 53 is suppressed. As a result, oxygen tends to remain inside the hard disk drive 1, and organic impurities remaining inside the hard disk drive 1 are easily decomposed by oxygen.

[0125] The fan 300 according to the second embodiment also includes a motor 320 .

[0126] According to the above-described blower 300, since it includes the motor 320, the defect rate in the process of winding the coil 371 around the stator core 370 having the same structure as the stator core 50 is improved. Therefore, the defect rate of the blower 300 is also improved.

[0127] Furthermore, the manufacturing method of the spindle motor 3 or the motor 320 according to the above embodiment includes a film-forming / heating process in which the surface of the laminate of the electromagnetic steel sheets 52 is painted by electrocoating with an epoxy resin-containing paint, and then the paint is heated and hardened by overbaking to form the coating film 53, thereby manufacturing the stator core 50, and a fixing process in which the stator core 50 manufactured in the film-forming / heating process is fixed to the base plate 30 of the spindle motor 3 or the base plate 340 of the motor 320.

[0128] Moreover, according to the method for manufacturing the spindle motor 3 or the motor 320 according to the above embodiment, the overbake in the film forming and heating process is performed at a temperature of 280° C. or higher.

[0129] Furthermore, the manufacturing method for the spindle motor 3 or the motor 320 according to the above embodiment includes a film-forming / first heating process in which the surface of the laminate of the electromagnetic steel sheets 52 is painted by electrocoating with an epoxy resin-containing paint and then heated and hardened by overbaking to form a coating film 53, a second heating process in which the coating film 53 is heated by overbaking at a temperature higher than that in the first heating process to manufacture the stator core 50, and a fixing process in which the stator core 50 manufactured in the second heating process is fixed to the base plate 30 of the spindle motor 3 or the base plate 340 of the motor 320.

[0130] Moreover, according to the method for manufacturing the spindle motor 3 or the motor 320 according to the above embodiment, the overbake in the second heating step is performed at a temperature of 280° C. or higher.

[0131] According to the above-described manufacturing method of the spindle motor 3 or the motor 320, the surface of the stator core 50 is painted by electrodeposition coating of an epoxy resin-containing paint, and then the paint film 53 is heated and hardened by overbaking. Therefore, since the paint film 53 having high hardness is formed by overbaking, it is possible to manufacture the spindle motor 3 or the motor 320 in which the coil 51 is unlikely to sink into the paint film 53 of the stator core 50 even if pressure is applied to the coil 51 in the step of winding the coil 51 around the stator core 50.

[0132] In addition, since the coil 51 is less likely to sink into the coating 53 of the stator core 50, winding defects are less likely to occur in the process of winding the coil 51 around the stator core 50, and the defect rate in the manufacturing process of the spindle motor 3 or the motor 320 is improved.

[0133] <Modification> The hard disk drive 1 may include a spindle motor 103 as shown in FIG. 8, instead of the spindle motor 3 described in the first embodiment.

[0134] <Spindle motor> The spindle motor 103 includes a stationary part 110 and a rotating part 120 that rotates relative to the stationary part 110 via a bearing mechanism.

[0135] (Stationary part) The stationary portion 110 includes a base plate 130 , a sleeve 140 , a stator core 150 , a magnetic attraction plate 160 , and a shaft 170 .

[0136] The base plate 130 is a metal member. The base plate 130 has a through hole 131, a circumferential groove portion 132, and a circumferential wall portion 133 formed therein.

[0137] The through hole 131 is a hole for fixing the sleeve 140. The through hole 131 is provided so as to penetrate the base plate 130 in the axial direction. The through hole 131 is cylindrical, and the inner diameter of the cylinder is approximately the same as or larger than the outer diameter of the sleeve 140.

[0138] The circumferential groove portion 132 is formed radially outward of the through hole 131. The circumferential groove portion 132 is an annular groove provided so as to be coaxial with the central axis of the through hole 131 when viewed in the axial direction.

[0139] The circumferential wall portion 133 is formed as an annular wall portion that protrudes axially upward along the through hole 131 from the bottom surface of the circumferential groove portion 132 when viewed in the axial direction. The circumferential wall portion 133 separates the through hole 131 and the circumferential groove portion 132.

[0140] The sleeve 140 fixes the shaft 170 to the base plate 130, and forms a dynamic pressure bearing between the sleeve 140 and the rotating part 120. The sleeve 140 is a cylindrical iron member such as stainless steel. The sleeve 140 is inserted into the through hole 131. The sleeve 140 is fixed to the through hole 131 by an adhesive applied to one or both of the outer circumferential surface of the sleeve 140 and the inner circumferential surface of the through hole 131. The sleeve 140 is formed with a sleeve through hole 141 and a sleeve recess 142.

[0141] The sleeve through hole 141 is provided at the center of the sleeve 140 when viewed in the axial direction, and is provided so as to axially penetrate the sleeve 140. The diameter of the sleeve through hole 141 is approximately the same as or larger than the outer diameter of the shaft 170.

[0142] The sleeve recess 142 is a recess formed in a circular shape in the sleeve 140 when viewed in the axial direction. The sleeve recess 142 is provided coaxially with the central axis of the sleeve through hole 141 when viewed in the axial direction. The sleeve recess 142 is connected to the sleeve through hole 141 and is formed above the sleeve through hole 141. A thrust dynamic pressure generating groove 143 is formed in the bottom surface of the sleeve recess 142. The thrust dynamic pressure generating groove 143 is provided in an annular shape when viewed in the axial direction.

[0143] The stator core 150 is a member in which a plurality of annular electromagnetic steel plates are laminated in the axial direction when viewed in the axial direction. The stator core 150 is disposed inside the circumferential groove portion 132 and fixed by a method such as adhesion. The surface of the stator core 150 is covered with a coating film 153. The stator core 150 has a plurality of pole teeth (salient poles) that extend radially outward and are disposed along the circumferential direction. Coils 151 are wound around the pole teeth. The stator core 150 generates magnetic flux when a current flows through the coils 151. The manufacturing method of the stator core 150 is the same as that of the stator core 50 of the first embodiment, and therefore a description thereof will be omitted.

[0144] The magnetic attraction plate 160 is a member that stabilizes the rotation of the rotor hub 180, which will be described later. The magnetic attraction plate 160 is made of, for example, a magnetic material. The magnetic attraction plate 160 generates a magnetic flux in response to a current applied to the coil 151. The magnetic attraction plate 160 is installed radially outward of the stator core 150 in the circumferential groove portion 132.

[0145] The shaft 170 is a cylindrical metal member. The outer diameter of the shaft 170 is approximately the same as or smaller than the inner diameter of the sleeve through hole 141. The lower side of the shaft 170 is inserted into the sleeve through hole 141. The shaft 170 is fixed to the sleeve through hole 141 with an adhesive applied to one or both of the outer circumferential surface of the shaft 170 and the inner circumferential surface of the sleeve through hole 141, and is connected to the sleeve 140. The shaft 170 has a radial dynamic pressure generating groove 171 and a flange portion 172.

[0146] The radial dynamic pressure generating grooves 171 are provided on the outer circumferential surface of the shaft 170 at a portion inserted into a rotor hub 180 (described later). In this modification, the radial dynamic pressure generating grooves 171 are formed in a continuous row in the circumferential direction on the outer circumferential surface of the shaft 170, and are formed in two rows spaced apart in the axial direction.

[0147] The flange portion 172 is formed integrally with the shaft 170 at the upper end of the shaft 170. The flange portion 172 has a cylindrical portion 173, a protruding portion 174, and a thrust dynamic pressure generating groove 175.

[0148] The cylindrical portion 173 is a member having a cylindrical shape coaxial with the central axis of the shaft 170. The cylindrical portion 173 is formed at the upper end portion of the flange portion 172 in the axial direction.

[0149] The protruding portion 174 is a member having an annular shape coaxial with the central axis of the shaft 170. The protruding portion 174 is formed so as to protrude radially outward from the lower end of the cylindrical portion 173. The outer peripheral side surface 176 of the protruding portion 174 is inclined in the axial direction. Therefore, when comparing the upper surface 174a and the lower surface 174b of the protruding portion 174, the outer diameter of the lower surface 174b is larger than the outer diameter of the upper surface 174a.

[0150] The thrust dynamic pressure generating groove 175 is formed in a lower surface 174b of the protruding portion 174. The thrust dynamic pressure generating groove 175 is provided in an annular shape when viewed in the axial direction.

[0151] (Rotating part) The rotating portion 120 includes a rotor hub 180 , a rotor magnet 190 , and an end cap 200 .

[0152] The rotor hub 180 is a member that rotates relative to the sleeve 140 and the shaft 170. The rotor hub 180 is disposed on the outside of the shaft 170, and a portion of its lower portion is disposed in the sleeve recess 142. The rotor hub 180 has an inner cylindrical wall portion 181, a disk portion 182, an outer cylindrical wall portion 183, an outer edge portion 184, a standing wall portion 185, and an annular groove 186.

[0153] The inner cylindrical wall portion 181 is a member having a substantially cylindrical shape. A gap 210a is formed between the lower end surface of the inner cylindrical wall portion 181 and the bottom surface of the sleeve recess 142 of the sleeve 140. A rotor hub through hole 187 that passes through the rotor hub 180 in the axial direction is formed in the center of the inner cylindrical wall portion 181 (a portion that corresponds to the rotation center of the rotor hub 180). The diameter of the rotor hub through hole 187 is larger than the outer diameter of the shaft 170. The shaft 170 is inserted into the rotor hub through hole 187. A gap 210b is formed between the inner circumferential surface of the rotor hub through hole 187 and the outer circumferential surface of the shaft 170.

[0154] The disk portion 182 is a disk-shaped member that is coaxial with the center of the inner cylindrical wall portion 181 when viewed in the axial direction. The disk portion 182 is formed from the upper end side of the inner cylindrical wall portion 181 toward the outside in the radial direction.

[0155] The outer cylindrical wall portion 183 is a cylindrical member having a thickness in the radial direction. The outer cylindrical wall portion 183 is provided so as to be coaxial with the center of the inner cylindrical wall portion 181 when viewed in the axial direction, and protrudes downward in the axial direction. The outer cylindrical wall portion 183 is provided on the outer edge of the disc portion 182.

[0156] The outer edge portion 184 is an annular member. The outer edge portion 184 is provided at the lower end of the outer cylindrical wall portion 183. The outer edge portion 184 protrudes radially outward from the outer cylindrical wall portion 183 and is formed in a flange shape. A plurality of recording disks 4 are installed above the outer edge portion 184 and radially outward from the outer cylindrical wall portion 183 (see FIG. 1).

[0157] The standing wall portion 185 is an annular member. The standing wall portion 185 is provided on the upper surface of the disk portion 182 radially outward with respect to the rotor hub through hole 187, and protrudes axially upward. The flange portion 172 is accommodated in a space radially inward of the standing wall portion 185. A gap 210c is formed between the upper surface of the disk portion 182 radially inward of the standing wall portion 185 and a lower surface 174b of the protruding portion 174.

[0158] The annular groove 186 is used for positioning and fixing the end cap 200. The annular groove 186 is provided on the upper surface of the disk portion 182, radially outward of the standing wall portion 185.

[0159] The rotor magnet 190 is an annular member having a magnetic pole structure magnetized with polarities inverted as N, S, N, S... along the circumferential direction when viewed in the axial direction. The rotor magnet 190 is attached to the inner peripheral surface of the outer cylindrical wall portion 183. The rotor magnet 190 is located at approximately the same position as the stator core 150 in the axial direction, and at approximately the same position as the magnetic attraction plate 160 in the radial direction.

[0160] The end cap 200 prevents leakage of lubricating oil used in the dynamic pressure bearing portion. The end cap 200 is a member having a substantially cylindrical shape. The end cap 200 has a top plate portion 201 and a side wall portion 202.

[0161] The top plate portion 201 is a circular member. An end cap through hole 203 is formed in the center of the top plate portion 201. The cylindrical portion 173 of the flange portion 172 is inserted into the end cap through hole 203. The inner peripheral surface of the end cap through hole 203 is disposed so as to closely face the outer peripheral surface of the cylindrical portion 173.

[0162] The side wall portion 202 is an annular member. The side wall portion 202 is provided so as to be coaxial with the center of the top plate portion 201 when viewed in the axial direction, and protrudes axially downward. The side wall portion 202 is provided on the outer edge of the top plate portion 201. The side wall portion 202 is housed in the annular groove 186 with its inner circumferential surface fitted into the standing wall portion 185. The end cap 200 is fixed to the rotor hub 180 by fixing the side wall portion 202 to the standing wall portion 185 and the annular groove 186 by means of adhesion, welding, or the like.

[0163] Lubricating oil is filled between the rotor hub 180 and the sleeve 140, and between the rotor hub 180 and the shaft 170. Specifically, the lubricating oil is filled in the gaps 210a, 210b, and 210c.

[0164] <Spindle motor operation> When the coil 151 is energized, a magnetic attraction force and a magnetic repulsion force are generated between the magnetic poles of the rotor magnet 190 and the pole teeth of the stator core 150. As a result, the rotating part 120 rotates relative to the stationary part 110 around the shaft 170.

[0165] Rotor hub 180 rotates relative to shaft 170. At this time, the lubricating oil is pressurized by radial dynamic pressure generating grooves 171 and thrust dynamic pressure generating grooves 175, generating dynamic pressure in the lubricating oil. The dynamic pressure generated by radial dynamic pressure generating grooves 171 supports rotor hub 180 in a non-contact state in the radial direction relative to shaft 170. In addition, the dynamic pressure generated by thrust dynamic pressure generating grooves 175 supports rotor hub 180 in a non-contact state in the axial direction relative to shaft 170.

[0166] The rotor hub 180 rotates relative to the sleeve 140. At this time, dynamic pressure is generated in the lubricating oil as the lubricating oil is pressurized by the thrust dynamic pressure generating grooves 143. The dynamic pressure generated by the thrust dynamic pressure generating grooves 143 supports the rotor hub 180 relative to the sleeve 140 in a non-contact state in the axial direction.

[0167] The structure of the spindle motor 103 in the modified example has been described above. Note that the above description is an example of the motor structure. Therefore, the motor structure is not limited to the above structure, and may be another structure.

[0168] ==Paint film evaluation== A laminate of magnetic steel sheets 52 was electrocoated with paint containing epoxy resin and aluminum silicate components, and then heated and cured to obtain a coating film 53. This coating film 53 was overbaked by heating at a heating temperature of 280° C. for 60 minutes.

[0169] (Fourier type infrared spectroscopy (FTIR) measurement) The IR absorption spectrum of each coating film 53 before and after overbaking was directly measured by the ATR method using diamond crystal. The obtained absorption spectrum is shown in Figure 6. Figure 9(A) shows the absorption spectrum before overbaking, and Figure 9(B) shows the absorption spectrum after overbaking.

[0170] In Figure 9, the wave number is 1490 cm -1 ~1520cm -1 The peak at 995 cm is due to epoxy resin. -1 ~1010cm -1 The peak at can be identified as a peak derived from the pigment. As shown in FIG. 9, by comparing the absorption spectrum before overbaking (FIG. 9(A)) with the absorption spectrum after overbaking (FIG. 9(B)), it can be confirmed that the peak intensity derived from the epoxy resin is significantly lower than the peak intensity derived from the pigment. Here, the peak intensity ratio before overbaking and the peak intensity ratio after overbaking (x=I polymer / I pigment ) was calculated to be x = 0.90 before overbaking and x = 0.41 after overbaking. [Explanation of symbols]

[0171] 1...Hard disk drive, 3, 103...Spindle motor (motor), 30, 130, 340...Base plate, 50, 150, 370...Stator core, 52...Electromagnetic steel plate, 53, 153, 373...Painting, 300...Blower, 320...Motor

Claims

1. A stator core is provided in which the surface of a laminate of electromagnetic steel sheets is covered with a coating film, The coating film is an overbaked epoxy resin-containing electrodeposition coating film. Motor.

2. The motor of claim 1 , wherein the coating has a pencil hardness of 5H or greater.

3. The coating film contains a benzene ring-containing epoxy resin and a pigment containing an aluminum silicate component, In the absorption spectrum obtained by Fourier infrared spectroscopy of the coating film, the peak intensity ratio x is calculated using the following formula (1): x=I ｐｏｌｙｍｅｒ / I ｐｉｇｍｅｎｔ ・・・(1) The value of I is 0.8 or less (where I ｐｏｌｙｍｅｒ is the peak intensity value of the wavenumber corresponding to the absorbance due to the benzene ring, I ｐｉｇｍｅｎｔ represents the peak intensity value of the wave number corresponding to the absorbance derived from the pigment containing the aluminum silicate component.

2. The motor according to claim 1.

4. A hard disk drive comprising the motor according to any one of claims 1 to 3.

5. 5. The hard disk drive according to claim 4, wherein the magnetic recording method of the hard disk drive is a thermally assisted magnetic recording method.

6. A blower comprising the motor according to any one of claims 1 to 3.

7. a film-forming and heating process in which a surface of the laminate of electromagnetic steel sheets is coated with an epoxy resin-containing paint by electrocoating, and the coating is heated and cured by overbaking to form a coating film, thereby manufacturing a stator core; a fixing process of fixing the stator core manufactured in the film forming and heating process to a base plate of a motor; A method for manufacturing a motor comprising:

8. The method for manufacturing a motor according to claim 7 , wherein the overbaking in the film forming and heating step is carried out at a temperature of 280° C. or higher.

9. a film-forming / first heating step of electrochemically coating a surface of the laminate of electromagnetic steel sheets with an epoxy resin-containing paint by electrochemical coating and then heating and curing the paint to form a coating film; A second heating step of over-baking the coating film at a temperature higher than that of the first heating step to manufacture a stator core; a fixing step of fixing the stator core manufactured in the second heating step to a base plate of a motor; A method for manufacturing a motor comprising:

10. The method for manufacturing a motor according to claim 9, wherein the overbaking in the second heating step is carried out at a temperature of 280° C. or higher.

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