JP2008271686A - Spindle motor and method of assembling the spindle motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method for spindle motor in which a magnet 7 and a hub 6 can be positioned easily and accurately in the axial direction during manufacture as well as an air gap is provided between the first end face 12 of the magnet 7 and the hub so that the magnetic flux by the magnet may not flow to the hub due to short-circuit between the magnet and the hub. <P>SOLUTION: In the magnet 7, two or more magnetic poles are magnetized in its circumferential direction. The second end face 11 of the magnet 7 is abutted against the planar part 14 of an adsorbing jig 13 for absorption, and the hub 6 is inserted along the periphery of the magnet 7. The third end face 10 of the hub 6 is abutted against the planar part 14 of the absorbing jig 13 and is kept in that state, and an adhesive interposed between the junction faces of the hub 6 and the magnet 7 is hardened. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a spindle motor used in a recording disk device or the like.

  Spindle motors are used in hard disks, polygon mirrors, optical disk devices and the like, but since they have recently been used in mobile devices, miniaturization of motors and low power consumption have been demanded.

  The conventional example of Patent Document 1 shows a configuration in which a gap is provided between the first end face 12 of the magnet 7 and the hub, as shown in FIG. In this configuration, since the magnet 7 and the hub 6 are not short-circuited at the first end face 12 of the magnet, the magnetic flux from the magnet 7 is prevented from flowing to the hub 6. If the magnetic flux from the magnet 7 flows to the hub 6, the magnetic flux that should originally act as the driving force of the motor cannot be obtained sufficiently, the motor efficiency (torque constant) is reduced, and the power consumption is increased. By doing so, an increase in power consumption can be prevented. However, as described in Patent Document 1, the spindle motor having the conventional configuration shown in FIG. 4 cannot easily position the magnet 7 in the axial direction at the time of manufacture, and can obtain necessary assembly accuracy. It becomes impossible to obtain motor characteristics as designed. As the motor becomes smaller and thinner, the assembly accuracy of the magnet 7 has a greater effect on the motor characteristics. Specifically, the suction acting between the magnet 7 and the base 5 (in the case of a magnetic body) and the stator core 9 is increased. Force and torque ripple will vary from the design value.

  Therefore, in Patent Document 1, as shown in FIG. 5, in a motor having a rotor in which a magnet 7 is attached to a hub 6 and a stator in which a stator core 9 is attached to a base 5, a protrusion 15 is provided on the hub 6. A configuration has been proposed in which the magnet 7 is positioned in the axial direction with respect to the hub 6 by bringing the first end face 12 of the magnet 7 into contact with the protrusion 15. With this configuration, the magnet 7 can be positioned with high accuracy, so that the motor characteristics as designed can be obtained with certainty.

Further, by forming the protrusion 15 on the hub 6, the contact area between the hub 6 and the magnet 7 is reduced, and the protrusion 15 is formed on the magnetically neutral portion of the magnet 7. By short-circuiting the hub 6, the magnetic flux from the magnet 7 is prevented from flowing to the hub 6 through the protrusion 15. With this configuration, it is possible to prevent an increase in power consumption.
JP 2006-246624 A

  However, in the spindle motor having the conventional configuration disclosed in Patent Document 1, the first end surface 12 of the magnet 7 and the hub 6 are in contact with each other, so that the protrusion 15 is formed in a magnetically neutral portion of the magnet 7. Even if formed, the short circuit cannot be completely prevented, the motor efficiency is lowered, and the power consumption is increased.

  Further, since there are variations in the dimensions of the magnets 7, the positions of the second end surfaces 12 of the magnets 7 vary due to the differences in the heights of the magnets 7 of the individual motors, and the motor characteristics as designed cannot be obtained. In particular, since the distance between the lower end surface 11 in the axial direction of the magnet 7 and the base 5 varies, the variation in the attractive force acting between the magnet 7 and the base 5 (in the case of a magnetic body) increases.

  The present invention solves the above-described problems and problems, and a gap is formed between the first end surface 12 of the magnet 7 and the hub so that the magnet 7 and the hub 6 are short-circuited and the magnetic flux generated by the magnet 7 does not flow to the hub 6. And a method for manufacturing a spindle motor that enables easy and high-precision positioning of the magnet 7 and the hub 6 in the axial direction at the time of manufacturing, and further reduces variation. .

  In order to solve the above problems and problems, the spindle motor assembling method and spindle motor of the present invention have a rotating member having a hub and an annular magnet coaxially attached to the hub, and a stationary member being a base, A stator core attached to the base, wherein the magnet and the stator core oppose each other in a circumferential direction; a first end face in the axial direction of the magnet; and a face opposite to the first end face of the magnet in the hub. In the method of assembling a spindle motor in which a gap is provided between the magnet and the magnet, the magnet is magnetized with two or more magnetic poles in the circumferential direction, has at least one plane portion, and one of the plane portions. A second end face that is in contact with the first end face of the magnet on the opposite side in the axial direction to the flat surface portion of the adsorption jig made entirely of a magnetic material. The hub is inserted along the peripheral surface of the magnet, and the third end surface of the hub opposite to the base is held in contact with the planar portion of the adsorption jig. The adhesive interposed between the hub and the magnet is hardened.

  According to the above invention, a space | gap can be provided between the axial direction upper side end surface of a magnet, and a hub. Therefore, it is possible to prevent the magnet and the hub from being short-circuited and the magnetic flux from the magnet from flowing to the hub.

  Furthermore, it is possible to easily and accurately position the third end face of the hub and the second end face of the magnet in the axial direction with the planar portion of the adsorption jig.

  Hereinafter, a spindle motor assembling method and a spindle motor according to embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
FIG. 1 is a cross-sectional view of a spindle motor according to Embodiment 1 of the present invention. In this spindle motor, a flange 2 and a hub 6 are attached to a shaft 1 to constitute a rotor that rotates around the shaft 1. A sleeve 4 is attached to the base 5 and a thrust plate 3 is attached to the sleeve 4 to constitute a stator.

  Here, a fluid bearing is formed between the shaft 1 and the flange 2, the sleeve 4, and the thrust plate 3, and the rotor is rotatably supported by the stator via the fluid bearing. In the present embodiment, the fluid bearing is described, but a ball bearing or a roller bearing may be used, and the type of the bearing is not limited.

  An annular magnet 7 magnetized with two or more magnetic poles in the circumferential direction is attached to the inner peripheral surface of the hub 6, and a stator core 9 is attached at a position facing the magnet 7 of the base 5 in the circumferential direction. When a controlled current is passed through the windings of the plurality of stator cores 9, a rotational force is generated between the stator 7 and the rotor 7 and the rotor acts as a drive mechanism for rotating the rotor.

  Further, a suction plate 8 made of a magnetic material is attached to the base 5, and the rotor is pressed against the stator side by generating a magnetic attraction force in the axial direction with the magnet 7. Therefore, even if vibration is applied, the rotor is prevented from flapping and the axial support of the rotor is stabilized. In this embodiment, the suction plate 8 is used. However, it is possible to obtain the same magnetic attraction force by forming the base 5 with a magnetic material.

  Here, the hub 6 and the magnet 7 are provided with a gap between the first end surface 12 of the magnet 7 and the hub 6 so that the third end surface 10 of the hub 6 and the second end surface 11 of the magnet 7 coincide. Is assembled. With this configuration, since the magnet 7 and the hub 6 are not short-circuited at the first end face 12 of the magnet, the magnetic flux generated by the magnet 7 does not flow to the hub 6 and an increase in power consumption can be prevented. It has become.

  FIG. 2 shows a method of assembling the spindle motor shown in FIG. First, after magnetizing two or more magnetic poles on the magnet 7, the second end face 11 of the magnet 7 is brought into contact with the flat portion 14 of the adsorption jig 13 made of a magnetic material. Since the magnet 7 is magnetized, a magnetic attraction force is generated between the adsorption jig 13 and the magnet 7, and the magnet 7 is adsorbed and fixed to the adsorption jig 13.

  Next, after applying an adhesive to the joint surface (inner peripheral surface) of the hub 6 with the magnet 7, the hub 6 is inserted along the peripheral surface of the magnet 7, and the hub 6 is inserted into the flat portion 14 of the adsorption jig 13. The third end face 10 is brought into contact. If the adhesive is hardened in this state, the axial positioning can be performed with high accuracy in a state where the third end face 10 of the hub 6 and the second end face 11 of the magnet 7 are matched. Further, since the positioning is performed by the second end surface 11 of the magnet 7, even if the molded magnet 7 having a slightly inferior dimensional accuracy is used for cost reduction, the second end surface 11 of the magnet 7 shown in FIG. Since the distance of the suction plate 8 can be made constant, variations in the suction force acting between the magnet 7 and the suction plate 8 can be suppressed, and motor characteristics as designed can be obtained.

  Here, if the assembly is performed without magnetizing the magnet 7, the magnet 7 is not attracted and fixed to the adsorption jig 13, so that the workability of the process of inserting the hub 6 into the magnet 7 becomes difficult. If the hub 6 has a cap shape as shown in the figure, when the magnet 7 is magnetized after being attached to the hub 6, it is difficult to insert a magnetizing yoke into the magnet 7, and the magnet 7 is not uniform in the axial direction.

  Furthermore, when assembling is performed using the adsorption jig 13 made of a nonmagnetic material instead of a magnetic material, when the hub 6 is inserted into the magnet 7, the gap between the first end surface 12 of the magnet 7 and the hub 6 is increased. Thus, a magnetic attractive force is generated, the first end surface 12 of the magnet 7 and the hub 6 are attracted, and a gap cannot be provided.

  Therefore, since the magnet 7 is attracted and fixed to the adsorption jig 13 by making contact with the adsorption jig 13 after magnetizing the magnet 7, the hub 6 and the magnet 7 can be easily assembled.

  By the way, when assembling is performed in the state of FIG. 2A, the adhesive may flow toward the adsorption jig 13 due to gravity. In that case, the magnet 7, the hub 6, and the adsorption jig 13 are bonded. On the other hand, as shown in FIG. 2B, when the lower surface side of the adsorption jig 13 is assembled as the plane portion 14, the adhesive can be prevented from flowing to the adsorption jig 13 side by gravity, and further assembled. Can be easily performed.

  Further, even when the adhesive flows to the adsorption jig 13 side and the magnet 7, the hub 6, and the adsorption jig 13 are bonded, the surface roughness of the adsorption jig 13 is determined by the second end face 11 of the magnet 7 and the hub 6. By making it smaller than the surface roughness of the third end face 10, the combined body of the magnet 7 and the hub 6 and the adsorption jig 13 can be easily peeled off. This utilizes the fact that the smaller the surface roughness is, the smaller the mechanical bonding force (anchor effect) of the adhesive is. That is, because the mechanical coupling force between the adsorption jig 13 and the adhesive is smaller than the mechanical coupling force between the magnet 7 or the hub 6 and the adhesive due to the difference in surface roughness, a shearing force is applied to the adhesive portion. And the adsorption jig 13 and the adhesive. Therefore, since the bonded body of the magnet 7 and the hub 6 and the adsorption jig 13 can be peeled off without the adhesive remaining on the adsorption jig 13 side, the assembly can be further facilitated.

  Similarly, by making the surface energy of the adsorption jig 13 smaller than the surface energy of the second end face 11 of the magnet 7 and the third end face 10 of the hub 6, the combined body of the magnet 7 and the hub 6 and the adsorption jig 13. Can be easily peeled off. This utilizes the fact that the smaller the surface energy, the worse the wettability, so that the adhesive does not spread on the surface and the bonding force becomes weak. That is, the adhesive itself is prevented from spreading on the surface of the adsorption jig 13 due to the difference in surface energy, and the bonding force between the adsorption jig 13 and the adhesive is bonded to the magnet 7 or the hub 6 and the adhesive even if it spreads. Since the force is smaller than the force, when a shearing force is applied to the adhesive portion, the adhesive jig 13 and the adhesive are separated from each other. Therefore, since the bonded body of the magnet 7 and the hub 6 and the adsorption jig 13 can be peeled off without the adhesive remaining on the adsorption jig 13 side, the assembly can be further facilitated. In order to reduce the surface energy of the adsorption jig 13, it is effective to coat at least the planar portion 11 of the adsorption jig 13. Fluororesin and DLC are known to have low surface energy and are particularly effective for coating.

(Embodiment 2)
FIG. 3 is an assembly diagram of the spindle motor according to the second embodiment of the present invention. In the first embodiment, the adsorption jig 13 is a flat surface, whereas in FIG. 3A, a step is provided in accordance with the magnet 7. This step can prevent the magnet 7 from moving in the left-right direction, further facilitating assembly.

  In FIG. 3B, the third end face 10 of the hub 6 is not the lowermost face of the hub 6 but is provided with a step. By adopting this shape, the position of the second end surface 11 of the magnet 7 can be set without being restricted by the outer shape (lowermost surface) of the hub, and the degree of freedom in design can be increased. In addition, by providing a step in the adsorption jig 13 in accordance with the step of the hub 6, it is possible to prevent the hub 6 from moving to the left and right, further facilitating assembly, and the hub 6 and the magnet 7. The coaxial accuracy can be improved.

  Furthermore, in FIG.3 (c) and FIG.3 (d), it is set as the structure which provided the plane part 14 of the adsorption jig 13 in two places. By adopting this shape, the position of the second end surface 11 of the magnet 7 can be set without being restricted by the outer diameter (lowermost surface) of the hub, and the degree of freedom in design can be increased. Furthermore, by changing the positional relationship between the two plane portions 14, the axial position of the hub 6 and the magnet 7 can be changed, and the design can be easily changed.

  In the above embodiment, the adhesive is applied to the hub 6, but it may be applied to the magnet 7, and if it is applied to both the hub 6 and the magnet 7, uneven adhesion can be reduced. Moreover, after making the hub 6 and the magnet 7 contact | abut to the adsorption | suction jig 13, you may inject | pour an adhesive agent into a junction part, and the order which interposes an adhesive agent in a junction part is not ask | required.

  Furthermore, in the above embodiment, the magnet 7 is configured as an outer rotor on the outer peripheral side of the stator core 9, but the magnet 7 may be configured as an inner rotor on the inner peripheral side of the stator core 9.

  In the above embodiment, an example in which the entire adsorption jig 13 is made of a magnetic material has been described. However, a part or all of the flat portion 14 with which the second end face 11 of the magnet 7 is in contact is made of a magnetic material. The adsorption jig 13 as a whole need not be a magnetic material.

  The present invention can be applied to a hard disk device and other devices, but can also be applied to other devices.

Sectional drawing of the spindle motor which concerns on the 1st Embodiment of this invention Assembly drawing of spindle motor according to first embodiment of the present invention Assembly drawing of spindle motor according to second embodiment of the present invention Cross section of another conventional spindle motor Cross section of another conventional spindle motor

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Shaft 2 Flange 3 Thrust plate 4 Sleeve 5 Base 6 Hub 7 Magnet 8 Suction plate 9 Stator core 10 3rd end surface 11 2nd end surface 12 1st end surface 13 Adsorption jig 14 Plane part 15 Protrusion part

Claims (8)

The rotating member has a hub and an annular magnet coaxially attached to the hub,
The stationary member has a base and a stator core attached to the base,
The magnet and the stator core are opposed in the circumferential direction,
In the assembling method of the spindle motor in which a gap is provided between the first end surface in the axial direction of the magnet and the surface of the hub facing the first end surface of the magnet,
The magnet is magnetized with two or more magnetic poles in the circumferential direction,
A second end face that contacts at least one of the flat end portions of the magnet and the first end face of the magnet is contacted with the flat portion of the adsorption jig that has at least one flat portion, and a part or all of the flat portion is made of a magnetic material. Adsorb and touch
Inserting the hub along the circumference of the magnet;
Holding the third end surface of the hub facing the base in contact with the planar portion of the adsorption jig;
An assembly method of a spindle motor, wherein an adhesive interposed between the hub and the magnet is hardened.   2. The method of assembling a spindle motor according to claim 1, wherein the adhesive is cured in a state in which the planar portion of the suction jig is axially downward and the third end surface of the hub is upward. .   2. The spindle motor according to claim 1, wherein a surface roughness of the planar portion of the adsorption jig is smaller than a surface roughness of the second end surface of the magnet and the third end surface of the hub. Assembly method.   2. The spindle motor assembling method according to claim 1, wherein the surface energy of the planar portion of the adsorption jig is smaller than the surface energy of the second end surface of the magnet and the third end surface of the hub. .   The spindle motor assembling method according to claim 4, wherein a coating is formed on at least the planar portion of the adsorption jig.   6. The spindle motor assembling method according to claim 5, wherein the coating is a fluororesin.   6. The method of assembling a spindle motor according to claim 5, wherein the coating is diamond-like carbon. A spindle motor assembled by the spindle motor assembling method according to claim 1.