JP2008199764A - Motor, and disk drive motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-quality motor in which a bearing is properly adhered and fixed to a prescribed position without the occurrence of harmful gas due to poor curing of an adhesive. <P>SOLUTION: A motor is provided with a bearing 12 whose one end is sealed while one end part of a rotor shaft 21 is protruded from the other-end opening part of the bearing. The bearing 12 is adhered and fixed to a bearing holding part 11a by an adhesive 16 in a state of being fitted to the bearing holding part. The adhesive 16 is composed of a first adhesive 16a and a second adhesive 16b separated from each other in an axial direction of the bearing 12. An annular groove 12a for separating the first adhesive 16a from the second adhesive 16b is formed on the outer periphery of one end part on the sealing side of the bearing 12 in the fitting part F between the bearing 12 and the bearing holding part 11a. The bearing is adhered and fixed to the bearing holding part 11a with the first adhesive 16a on the opening side of the bearing 12 from the annular groove 12a. While, the bearing is adhered and fixed to the bearing holding part 11a with the second adhesive 16b on the sealing side of the bearing 12 from the annular groove 12a. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a motor used as a drive source for various apparatuses, and more particularly to a disk drive motor for rotating a disk such as a hard disk, CD, CD-ROM, or DVD.

  In recent years, as various devices including a hard disk drive (HDD) become smaller and thinner, a motor as a drive source is also required to be smaller and thinner. In order to reduce the size of the motor without impairing the motor performance, an advanced assembling technique is indispensable. One of them is to fix and fix the motor constituent member with an adhesive. As the adhesive, an ultraviolet curable anaerobic adhesive is frequently used.

  For example, in FIG. 7, the bearing Be that rotatably supports the rotor shaft Rs is fitted into the cylindrical portion cy of the base frame Bf from the sealing side (the side where the seal plate Sp is mounted). The joint F is bonded and fixed to the base frame Bf by the adhesive A.

  According to this, since the bearing Be can be assembled without being compressed in the radial direction, the rotational performance of the rotor shaft Rs is not impaired, and the bearing Be can be fixed only by curing the adhesive A, so that the productivity is increased. There are advantages.

  However, when the bearing Be is bonded and fixed, the adhesive A is applied to the outer peripheral surface of the bearing Be and the inner peripheral surface of the cylindrical portion cy, and the bearing Be is fitted into the cylindrical portion cy in this state. Thus, most of the adhesive A is handled by the bearing Be and pushed out of the fitting portion F. Here, when an ultraviolet curable anaerobic adhesive is used as the adhesive A, the adhesive A left in the fitting portion F is cured well in a state where the air is shut off. The portion Ao is not cured because it is exposed to the outside air, and the ultraviolet ray does not reach deep inside even when irradiated with ultraviolet rays, so that the portion remains uncured. The uncured protruding portion Ao may generate harmful gas such as corroding the disk, and there is a concern that information cannot be recorded and reproduced by using a disk drive motor.

  Some UV-curing anaerobic adhesives are said to have thermosetting properties, but such adhesives are not as cured as pure thermosetting adhesives. Although the surface of the protruding portion Ao is cured, there is a possibility that an uncured portion remains inside.

  In order to eliminate the curing failure of the adhesive, it is only necessary to eliminate the protruding portion Ao, but it is extremely difficult to adjust the coating amount of the adhesive so as to eliminate the protruding portion Ao of the adhesive. Even if the application amount of the adhesive is adjusted, the amount of the protruding portion Ao is eliminated because the adhesive is excessive or insufficient depending on the processing accuracy of the fitting portion F (the outer diameter accuracy of the bearing / the inner diameter accuracy of the cylindrical portion). This is practically impossible, and if the application amount of the adhesive is reduced in order to eliminate the protruding portion Ao, the bearing Be will rattle due to insufficient adhesive strength and the rotational performance of the rotor shaft Rs will be lost. .

  The anaerobic adhesive is acrylic, and its curing reaction is a reaction form in which carbon double bonds are connected in a straight chain. For this reason, the bearing Be may be deformed by the hardening, and the rotational performance of the rotor shaft Rs may be impaired.

  On the other hand, it is conceivable to use a thermosetting adhesive in order to eliminate the curing failure of the protruding portion Ao. However, according to the ultraviolet curable anaerobic adhesive as described above, it is fitted while being in a room temperature state. The joint F immediately cures, and the protruding portion Ao can be cured while leaving an uncured portion inside by UV irradiation, whereas the thermosetting adhesive does not have such advantages, so the line There is a possibility that the mass production cannot be performed, and the fixing position of the bearing Be is shifted before shifting to the heat curing process, and the bearing Be is bonded and fixed in that state.

  Therefore, the cylindrical portion cy of the base frame and the bearing Be are bonded and fixed with an anaerobic adhesive filled in the gap (fitting portion F) between them, while the fitting portion F of the bearing Be is sealed on the sealing side of the bearing Be. There has been a proposal that an ultraviolet curable adhesive is applied to one end and cured by ultraviolet irradiation (for example, Patent Document 1).

JP 2000-82252 A (paragraphs 0076 to 0077, FIG. 3)

  However, when two types of adhesives are used as in Patent Document 1, the adhesives may be mixed before curing, and a good curing reaction may not occur at the mixed portion.

  In this regard, in Patent Document 1, there is no problem because an ultraviolet curable adhesive is applied and cured after curing of the anaerobic adhesive, but even in this case, anaerobic adhesion is applied to the portion where the ultraviolet curable adhesive is to be applied. Since it is necessary to apply a little anaerobic adhesive so that the agent is not pushed out, there is a high possibility that the adhesive strength will be insufficient due to the insufficient amount. If the shortage of anaerobic adhesive is to be compensated with UV curable adhesive, the thickness will increase and UV rays will not reach deep inside, resulting in a poor curing reaction. In addition, an uncured portion that becomes a source of harmful gas remains.

  The present invention has been made in view of the circumstances as described above, and its purpose is to prevent the generation of harmful gases due to poor curing of the adhesive, and to provide a high quality bearing that is appropriately bonded and fixed in place. It is to provide a motor.

In order to achieve the above object, the present invention
In a motor that is sealed at one end and includes a bearing 12 that supports the rotor shaft 21, and the bearing 12 is adhesively fixed to the bearing holding portion 11 a by an adhesive 16.
The adhesive 16 comprises a first adhesive 16a and a second adhesive 16b separated in the axial direction of the bearing 12,
In the fitting portion F between the bearing 12 and the bearing holding portion 11a, the first adhesive 16a and at least one of the outer periphery of the bearing 12 and the inner periphery of the bearing holding portion 11a on one sealed end side of the bearing 12 An annular groove 12a (11b) for separating the second adhesive 16b is formed,
The bearing 12 is bonded and fixed to the bearing holding portion 11a with the first adhesive 16a on the other end side opposite to the sealed end of the bearing 12 from the annular groove 12a (11b).
The bearing 12 is bonded and fixed to the bearing holding portion 11a only by the second adhesive 16b on one end side of the bearing 12 sealed from the annular groove 12a (11b).

  In addition, the first adhesive 16a is a thermosetting adhesive, and the second adhesive 16b is an anaerobic adhesive or an ultraviolet curable thermosetting adhesive.

  Further, a rotor hub 22 for holding a disk is fixed to the rotor shaft 21.

  According to the motor of the present invention, since the first adhesive and the second adhesive are separated in the axial direction of the bearing, the adhesive is cured by performing a curing reaction according to the properties of each of the adhesives. be able to. For this reason, generation | occurrence | production of noxious gas can be prevented.

  In particular, since an annular groove for separating the first adhesive and the second adhesive is formed in the fitting part between the bearing and the bearing holding part, the first adhesive and the second adhesive are applied simultaneously. However, it can be cured well without mixing the two adhesives.

  In addition, in the structure which forms an annular groove in the outer periphery of a bearing, the application | coating area | region of the 1st adhesive agent with respect to a bearing is prescribed | regulated by the annular groove, and a 1st adhesive agent is applied to the outer periphery of the end of the sealing side of a bearing. Can be prevented. That is, if the first adhesive is applied to the outer periphery of the bearing on the opposite side (opening side) of the bearing from the annular groove, the bearing is fitted into the bearing holding portion from the sealing side. Even if one adhesive is handled by the bearing holding portion and extends to the opening side of the bearing and a part of the first adhesive tries to flow to the sealing side of the bearing, this can be stopped by the annular groove. Therefore, even if the second adhesive is applied to one end of the fitting portion on the sealing side of the bearing, the second adhesive is not mixed with the first adhesive, and the bearing and the bearing holding portion on the opening side of the bearing from the annular groove. The first adhesive can be filled in the fitting portion, and the bearing can be firmly bonded and fixed by the first adhesive.

  In addition, since the bearing can be securely fixed with the first adhesive, the adhesive strength of the bearing will not be insufficient even if the amount of the second adhesive applied is too small, thereby limiting the amount of the second adhesive applied to a small amount. Since the protruding portion can be reduced, it can be reliably cured to suppress generation of harmful gas.

  In addition, since the first adhesive is a thermosetting adhesive, it does not cure and shrink like an acrylic anaerobic adhesive, and therefore deformation that adversely affects the rotational performance of the rotor shaft. It can be prevented from occurring in the bearing.

  In addition, since the second adhesive is an anaerobic adhesive or an ultraviolet curable thermosetting adhesive, the second adhesive is cured in a normal temperature environment before the first adhesive is heated and cured. Since the bearing can be held in an appropriate fixing position until the first adhesive is heated and cured, it is possible to mass-produce high-quality motors on the conveyance line.

  Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a longitudinal sectional view showing a motor according to the present invention. In this example, the motor is incorporated in a disk drive device (not shown) as a disk drive motor for rotating a hard disk or the like, but its form is a rotor 2 (rotor) on the outer periphery of the stator 1 (stator). The outer rotor type is provided.

  In this example, the stator 1 includes a base frame 11 having a cylindrical cylindrical portion 11a at the center portion as a bearing holding portion, a cylindrical bearing 12 fitted into the cylindrical portion 11a, and the like. The base frame 11 is made of aluminum or the like, and a stator core 13 made of a laminate of silicon steel plates is fixed to the outer periphery of the cylindrical portion 11a.

  The stator core 13 has a plurality of magnetic pole teeth 13a (tooth-like protrusions) that spread radially, and a conductor wire (coil winding) such as a copper wire coated with an insulating film is wound around each magnetic pole tooth 13a. A stator coil 14 is formed.

  The bearing 12 is a dynamic pressure type radial fluid bearing formed of sintered metal, stainless steel, or the like. One end of the bearing 12 is sealed with a seal plate 15 and the other end projects one end of a rotor shaft 21 described later. Open as much as possible. In particular, the bearing 12 is bonded and fixed to the base frame 11 with an adhesive 16 to be described later in a state of being fitted to the cylindrical portion 11a of the base frame in order to obtain high assembly accuracy.

  A rotor shaft 21 made of stainless steel or the like is inserted into the bearing 12, and the rotor shaft 21 is rotatably supported via lubricating oil filled in the bearing 12.

  As shown in FIG. 1, a flange portion 21a sandwiched between the bearing 12 and the seal plate 15 is formed on the outer periphery of one end of the rotor shaft 21, and the bearing 12 and the seal facing the flange portion 21a or both upper and lower surfaces of the flange portion 21a. A dynamic pressure generating groove (not shown) is formed in a portion of the plate 15 so that a thrust load acting on the rotor shaft 21 is supported by pressurization of lubricating oil.

  Further, as shown in FIG. 1, a herringbone-shaped dynamic pressure generating groove 21b is also formed on the outer peripheral portion of the rotor shaft 21, so that a radial load acting on the rotor shaft 21 is supported by pressurization of lubricating oil. However, such a groove may be formed on the inner peripheral surface of the bearing 12 or may be formed on both the bearing 12 and the rotor shaft 21. The bearing 12 is not limited to the dynamic pressure type, and can be replaced with other sliding bearings or rolling bearings.

  On the other hand, the rotor 2 includes the rotor shaft 21 and the rotor hub 22 fixed to the rotor shaft 21. The rotor hub 22 is a member having a concave cross section formed of stainless steel or the like, and its center is fixed to one end portion of the rotor shaft 21 protruding from the bearing 12. In particular, a flange 22a is formed on the outer periphery of the rotor hub 22, and a disk (not shown) (hard disk in this example) is supported by the flange 22a. A yoke 23 made of a magnetic material is fixed to the bottom of the rotor hub 22, and the yoke 23 is required to generate a rotational force in the vicinity of the tip surface (saliency pole) of each magnetic tooth portion 13 a of the stator core 13. A field magnet 24 that generates a large magnetic flux (field magnetic flux) is mounted. The field magnet 24 is a ring-shaped permanent magnet in which N poles and S poles are alternately magnetized in the circumferential direction, and the surface thereof is plated with nickel.

  According to the motor configured as described above, a driving current (armature current) is supplied to the stator coil 14 to generate a rotating magnetic field, and the magnetic flux of the field magnet 24 is applied to this to rotate the rotor hub 22. Is done.

  Next, FIG. 2 shows a partially enlarged cross section of the motor. As is apparent from this figure, in the fitting portion F between the bearing 12 and the base frame 11 (cylindrical portion 11a), the bearing 12 has an annular groove 12a on the outer periphery of one end portion on the sealing side (sealing plate 15 side). (In this example, a depth of about 0.5 mm and a width of about 1.0 mm) are formed. The bearing 12 is bonded and fixed to the base frame 11 (more precisely, the cylindrical portion 11a of the base frame) with the adhesive 16 in a state of being fitted to the cylindrical portion 11a as described above. In particular, two types of adhesives (first adhesive 16a and second adhesive 16b) are used as the adhesive 16, and both the adhesives 16a and 16b are separated in the axial direction of the bearing 12 with the annular groove 12a interposed therebetween. Has been.

  The first adhesive 16a is a thermosetting adhesive, which is filled in the fitting portion F between the bearing 12 and the cylindrical portion 11a on the opening side (rotor hub 22 side) of the bearing 12 from the annular groove 12a. Thus, the bearing 12 is firmly fixed to the base frame 11 by adhesion. In addition to the curing agent systems represented by epoxy resins containing curing agents, thermosetting adhesives include methylol systems such as phenol, urea, melamine, resorcinol, xylene resin, furan resin, and polyester systems. However, in this example, a curing agent-based epoxy adhesive that can be reliably cured without contraction by heat treatment is used.

  On the other hand, the second adhesive is an ultraviolet curable anaerobic adhesive (an anaerobic adhesive belonging to acrylic and an ultraviolet sensitizer is added) on the sealing side of the bearing 12 from the annular groove 12a. It is applied to one end of the fitting portion F.

  Next, an assembly example of the motor configured as described above will be described. Here, when the bearing 12 is bonded and fixed to the base frame 11, the stator core 13 around which the stator coil 14 is wound is attached to the base frame 11 as shown in FIG. After inserting the rotor shaft 21 to which the bearing 21 a is fixed into the bearing 12, one end of the bearing 12 is sealed by mounting the seal plate 15, and one end of the rotor shaft 21 protruding from the other end opening of the bearing 12 The rotor hub 22 is attached.

  The first adhesive 16a is applied to the outer peripheral surface of the bearing 12 along the annular groove 12a by a dispenser (not shown) on the opening side of the bearing 12 (the mounting side of the rotor hub 22) from the annular groove 12a. The second adhesive 16b is applied to the inner peripheral surface of the portion 11a at a position corresponding to the outer periphery of one end of the bearing 12 on the sealing side.

  Thereafter, the bearing 12 is fitted into the cylindrical portion 11a from the sealing side. At this time, the first adhesive 16a is handled by the cylindrical portion 11a and the fitting direction of the bearing 12 as shown in FIG. Extends to the opposite side (opening side of the bearing 12), and this is filled in the fitting portion F on the opening side of the bearing 12 from the annular groove 12a. Even if the excessive application of the first adhesive 16a is pushed out from the fitting portion F to the opening side of the bearing 12 (the rotor hub 22 side), all of the first adhesive 16a is heated by the subsequent heat treatment. Since the first adhesive 16a is made of an epoxy-based thermosetting adhesive, curing shrinkage hardly occurs and deformation of the bearing 12 can be prevented.

  On the other hand, the second adhesive 16 b is handled by the bearing 12 and is extended in the fitting direction of the bearing 12. And in the fitting part F, the 2nd adhesive agent 16b hardens | cures immediately under an air interruption state. Therefore, the bearing 12 can be temporarily fixed at a fixed position without waiting for the first adhesive 16a to harden, and in this state, the first adhesive 16a is subjected to heat treatment (90 ° C./1 in this example). Time), the bearing 12 can be firmly bonded and fixed in a fixed position.

  Incidentally, the second adhesive 16b having anaerobic property is markedly cured and shrunk and may deform the bearing 12, but its application region is one end of the fitting portion F on the sealing side of the bearing 12, Since this is a position deviating from the axial length of the rotor shaft 21 (a portion not directly involved in supporting the radial load of the rotor shaft 21), this does not impair the rotational performance of the rotor shaft 21.

Further, although the second adhesive 16b is handled by the bearing 12 and a part of the second adhesive 16b may protrude from the fitting part F as shown in FIG. The thickness t is also reduced (actually, the application amount of the second adhesive is limited so that the thickness t is 2 mm or less), and thus the protruding portion is irradiated with ultraviolet rays (1000 mJ / cm ² ). Can be reliably cured. And after hardening of the 2nd adhesive agent 16b, the 1st adhesive agent 16a is heat-hardened as mentioned above, and a motor like FIG. 1 can be obtained.

  In the above, a preferred example of the motor according to the present invention has been described. However, the motor is not limited to a disk drive but can be used as a drive source for various devices. The second adhesive 16b is not limited to an ultraviolet curable anaerobic adhesive, and may be an ultraviolet curable thermosetting adhesive or a simple anaerobic adhesive that does not contain an ultraviolet sensitizer. The effect of can be obtained.

  In the above example, the annular groove is formed on the outer periphery of the bearing 12. However, if the annular groove is on the sealing side of the bearing 12 that is not directly involved in supporting the radial load of the rotor shaft 21, the tubular portion You may form in the inner periphery of 11a, and may form in both the outer periphery of the bearing 12, and the inner periphery of the cylindrical part 11a. In the case where annular grooves are formed on both the outer periphery of the bearing 12 and the inner periphery of the cylindrical portion 11a, the annular grooves may be formed at positions facing each other, but as shown in FIG. An annular groove 12a is formed on the outer periphery of the cylindrical portion 11b, while an annular groove 11b is formed on the inner periphery of the cylindrical portion 11a at a position closer to the sealing side of the bearing 12, and the annular grooves 12a and 11b are positioned in the axial direction. It is preferable that the first adhesive 16a and the second adhesive 16b are separated from each other.

  As shown in FIG. 6, if the annular groove 3 is provided in the other part of the motor, the base frame 11 and the stator core 13, the yoke 23 and the field magnet 24, and the rotor hub 22 and the rotor shaft 21 are also of two types. It can be suitably bonded and fixed using an adhesive.

1 is a longitudinal sectional view showing a configuration example of a motor according to the present invention. Partial enlarged sectional view showing the main part of the motor Explanatory drawing which shows the assembly example of the motor which concerns on this invention Enlarged sectional view showing the adhesive fixing part of the bearing Partial enlarged sectional view showing another application example according to the present invention Reference drawing showing another embodiment of the motor according to the present invention Partial enlarged sectional view showing a conventional motor Expanded cross-sectional view showing the adhesive fixing part of the bearing in the conventional motor

Explanation of symbols

1 Stator 11 Base frame 11a Cylindrical part (bearing holding part)
11b annular groove 12 bearing 12a annular groove 15 seal plate 16 adhesive 16a first adhesive 16b second adhesive 2 rotor 21 rotor shaft 22 rotor hub

Claims (3)

In a motor that is sealed at one end and includes a bearing that supports a rotor shaft, and the bearing is bonded and fixed to the bearing holding portion by an adhesive.
The adhesive consists of a first adhesive and a second adhesive separated in the axial direction of the bearing,
In the fitting portion between the bearing and the bearing holding portion, the first adhesive and the second adhesive are attached to at least one of the outer periphery of the bearing and the inner periphery of the bearing holding portion on one end side where the bearing is sealed. An annular groove for separating the agent is formed,
The bearing is bonded and fixed to the bearing holding portion with the first adhesive on the other end side opposite to the sealed end of the bearing from the annular groove,
The motor, wherein the bearing is bonded and fixed only to the bearing holding portion with the second adhesive at one end side of the bearing sealed from the annular groove.   The motor according to claim 1, wherein the first adhesive is a thermosetting adhesive, and the second adhesive is an anaerobic adhesive or an ultraviolet curable thermosetting adhesive.   3. The disk drive motor according to claim 1, wherein a rotor hub for holding the disk is fixed to the rotor shaft.

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