JP4902389B2 - Bearing inspection method and motor manufacturing method - Google Patents

Description

  The present invention relates to a bearing inspection method for performing contact or non-contact inspection of a fluid dynamic bearing motor, and a motor manufacturing method.

  A hydrodynamic bearing motor has a structure in which, for example, a rotating shaft fixed at the center of a rotor is inserted into a sleeve formed on the stator, and fluid such as oil or air is interposed between the rotating shaft and the sleeve. In addition, fluid dynamic pressure is generated in the fluid with the rotation of the rotation shaft, and when the rotation speed exceeds a predetermined number of rotations, the rotation shaft and the sleeve are brought into a non-contact state and rotate. In this way, the hydrodynamic bearing motor rotates in a non-contact state between the rotating shaft and the sleeve, so that it has high durability with little friction and wear between the rotating shaft and the sleeve, and it can handle high-speed rotation with low rotational noise. In addition to being used for rotating hard disks, it is often used as a rotation motor for various recording media.

  FIG. 5A and FIG. 5B are sectional views showing an outline of the configuration of a known fluid bearing motor. 5A shows an example of a fluid bearing motor using a slide bearing in the thrust direction, and FIG. 5B shows an example of a fluid bearing motor using a fluid dynamic pressure bearing in both the thrust direction and the radial direction.

  The rotor 40 constituting the hydrodynamic bearing motor 60 using the sliding bearing in the thrust direction shown in FIG. 5A has a substantially cup-shaped hub 44 opened downward and one end press-fitted into a hole provided in the center of the hub 44. And a fixed rotation shaft 45. A screw hole 49 for attaching a member such as a hard disk is formed coaxially with the rotary shaft 45 on one end side of the rotary shaft 45 which is press-fitted and fixed. Further, a radial of a predetermined shape is formed on the outer peripheral surface of the rotary shaft 45. A dynamic pressure groove 48 is formed. A ring-shaped yoke 46 is fixed to the bottom surface of the hub 44 so as to be coaxial with the hub 44 and along the outer periphery of the hub 44, and a permanent magnet 47 is bonded and fixed to the inner peripheral surface of the yoke 46.

  The stator 50 constituting the fluid dynamic bearing motor 60 includes a base plate 51 and a sleeve 52 that is formed on the base plate 51 and supports the rotating shaft 45. A radial dynamic pressure groove 56 is formed on the inner peripheral surface of the sleeve 52, and a coil 53 is formed in an extending portion 57 at the lower portion of the outer peripheral surface of the sleeve 52 so as to face the permanent magnet 47 bonded and fixed to the rotor 40. The core 54 around which is wound is fixed.

  In the hydrodynamic bearing motor 60, the rotating shaft 45 of the rotor 40 is rotatably inserted into the sleeve 52 of the stator 50. The rotating shaft 45, the sleeve 52, and an insulating thrust plate 71 disposed on the bottom of the sleeve 52 are provided. It is formed by filling a lubricant 55 such as oil in the gap. Note that the tip of the rotating shaft 45 has a curved surface and abuts against the thrust plate 71 to support the rotor 40 in the axial direction.

  The rotor 40a of the fluid dynamic bearing motor 60a using the fluid dynamic pressure bearing in both the thrust direction and the radial direction shown in FIG. 5B has a configuration substantially equivalent to the rotor 40 of the fluid dynamic bearing motor 60 described above. A difference is that a ring-shaped flange 201 in which a thrust dynamic pressure groove (not shown) is formed on the upper surface and the lower surface of the rotating shaft 45a is press-fitted and fixed.

  Further, the stator 50a of the hydrodynamic bearing motor 60a also has a configuration substantially the same as the stator 50 of the hydrodynamic bearing motor 60 described above, but the rotary shaft 45a is pivotally supported in a hole formed in the base plate 51a. The difference is that the sleeve 52a is press-fitted and fixed, and the thrust plate 71a is fixed at an interval that opposes the lower end surface of the sleeve 52a and allows the ring-shaped flange 201 to move. The thrust plate 71a and the sleeve 52a may be provided with a predetermined thrust dynamic pressure groove on the surface facing the ring-shaped flange 201.

  The rotor 40a of the fluid dynamic bearing motor 60a is attached so that the rotating shaft 45a and the ring-shaped flange 201 are rotatable with respect to the stator 50a. The fluid bearing motor 60a is formed by filling a lubricant 55 such as oil in a gap between the rotary shaft 45a and the ring-shaped flange 201 and the sleeve 52a, the thrust plate 71a and the like. In the hydrodynamic bearing motor 60a, dynamic pressure is generated in the lubricant 55 at the time of rotation by the radial dynamic pressure grooves 48 and 56 formed in the rotary shaft 45a and the sleeve 52a. Thus, the rotor 40a is supported in the radial direction during rotation. At the same time, dynamic pressure that causes the rotary shaft 45a to float is generated in the lubricant 55 by the thrust dynamic pressure grooves formed on the upper and lower surfaces of the ring-shaped flange 201 at the tip of the rotary shaft 45a. Thereby, the rotor 40a is also supported in the axial direction during rotation.

  The hydrodynamic bearing motor 60a as described above is generated by the radial dynamic pressure grooves 48 and 56 and the thrust dynamic pressure grooves of the ring-shaped flange 201 when the rotational speed of the rotor 40a exceeds a predetermined rotational speed (floating rotational speed). Due to the dynamic pressure, the rotating shaft 45a and the ring-shaped flange 201 rotate in a non-contact state with respect to the sleeve 52a and the thrust plate 71a, and are normally used in this non-contact rotation state. Further, in the fluid dynamic bearing motor 60 described above, when the rotational speed of the rotor 40 exceeds a predetermined rotational speed (floating rotational speed), the rotary shaft 45 is thrust plate due to the dynamic pressure generated by the radial dynamic pressure grooves 48 and 56. The sleeve 52 is rotated in a non-contact state while being in a point contact state, and is normally used in this state. In the following description, the rotating shaft 45 is not in contact with the sleeve 52 during rotation, and the rotating shaft 45a is not in contact with the stator 50a both in the radial direction and in the axial direction. This will be referred to as surfacing for convenience. In the following description regarding the contact and non-contact between the rotating shaft and the stator, the rotating shaft 45a includes the rotating shaft 45a and the ring-shaped flange 201, and the sleeve 52a refers to the sleeve 52a. It shall mean what includes the thrust plate 71a. That is, the state where the rotating shaft 45a and the sleeve 52a are in contact indicates the state where the rotating shaft 45a or the ring-shaped flange 201 is in contact with the sleeve 52a or the thrust plate 71a.

  Here, when the flying rotation speed of the manufactured motor is higher than a predetermined value set in advance due to some trouble, the hydrodynamic bearing motors 60 and 60a continue to rotate in a contact state from the time of startup, and the rotation shaft In addition to the shortening of the service life due to wear or the like, there is a possibility that the operation itself of the fluid dynamic bearing motors 60 and 60a may be hindered. Therefore, the flying speed is one of the important characteristics of the hydrodynamic bearing motors 60 and 60a, and is one of the main inspection processes in the process of manufacturing the hydrodynamic bearing motors 60 and 60a. The rotating shaft 45 of the hydrodynamic bearing motor 60 always rotates in contact with the thrust plate 71. In addition to the point contact as described above, this contact state is normally resistant to the thrust plate 71. Since a highly wearable resin is used, wear due to this contact state hardly occurs. Therefore, this contact state does not adversely affect the life and operation of the hydrodynamic bearing motor 60.

  As a method for inspecting the floating rotational speed of a fluid dynamic bearing motor, the following [Patent Document 1] describes that the impedance between a shaft element and a bearing element of a fluid bearing (dynamic pressure bearing in Patent Document 1) is in non-contact with the contact rotation. An invention relating to a bearing inspection method and a bearing inspection device for inspecting the floating rotational speed of a fluid dynamic bearing motor based on changes in rotation is disclosed. Here, the figure explaining the conventional bearing test | inspection apparatus described in [patent document 1] in FIG. 6 is shown. The bearing inspection apparatus shown in FIG. 6 has the excitation electrode 11 on the side surface of the hub 44 (disc hub in Patent Document 1) of the fluid dynamic bearing motor 60a and the detection electrode 12 for measurement on the upper end surface of the hub 44. The excitation electrode 11 generates electric lines of force in the hub 44 by the AC voltage from the AC voltage power supply 13, and the detection electrode 12 transmits the electric lines of force of the hub 44 to the inductor L1. An oscilloscope 14 is connected to both ends of the inductor L1 to detect the voltage across the inductor L1. The hub 44 and the excitation electrode 11, the excitation electrode 11 and the detection electrode 12, the base plate 51a and the excitation electrode 11, and the hub 44 and the detection electrode 12 each have a predetermined capacitance. The capacitor C2, C3, C5, and C4 are described. The voltage detected by the oscilloscope 14 differs between when the rotating shaft 45a of the fluid dynamic bearing motor 60a rotates in contact with the sleeve 52a and when it rotates in a non-contact state. The floating rotational speed is measured from the voltage difference, and the floating rotational speed of the hydrodynamic bearing motor 60a is inspected. In addition, in [Patent Document 1], as a modification, a configuration in which the levitation speed is inspected from the detection voltage at both ends of the resistor connected to the excitation electrode without using the detection electrode 12, or the electrode is directly connected to the hub 44. There is also a description of a configuration in which the floating rotation speed is inspected by contact.

JP 2002-131187 A

  In the invention described in [Patent Document 1], the excitation electrode 11 and the detection electrode 12 are arranged close to the hub 44 constituting the rotor 40a of the fluid dynamic bearing motor 60a to electrically increase the floating rotational speed of the fluid dynamic bearing motor 60a. Although the inspection is performed, in order to obtain a detection voltage sufficient for the inspection of the levitation speed, it is necessary to extremely narrow the distance between the hub 44 and the excitation electrode 11 and the detection electrode 12. However, when the rotor 40a of the hydrodynamic bearing motor 60a rotates, a certain amount of mechanical vibration is generated. Therefore, the rotor 40a and the excitation electrode 11 or the detection electrode 12 come into contact with each other due to this mechanical vibration. Can not do.

  In the method of inspecting the flying speed by directly contacting the electrode with the rotor 40a of the fluid dynamic bearing motor 60a, the rotation speed of the rotor 40a is reduced or the torque is small due to the load pressing the electrode against the rotor 40a. It is difficult to accurately measure the number of levitation rotations because the motor stops rotating.

  If the inspection of the levitation speed by the above inspection method is used in the inspection process of the motor manufacturing method, the levitation speed of the hydrodynamic bearing motor cannot be accurately measured. It is necessary to set this, and there is concern about a decrease in yield due to this, and there is no denying the possibility that defective products will flow out.

  The present invention has been made in view of the above circumstances, a bearing inspection method capable of inspecting the floating rotational speed of a fluid dynamic bearing motor in a simple and accurate manner with a low load on the motor, and a floating rotation using the bearing inspection method. It is an object of the present invention to provide a method for manufacturing a motor that performs numerical inspection.

The present invention provides a bearing test for determining whether or not the rotor 40a and the stator 50a are in contact with each other in a motor in which the rotor 40a is rotatably supported by a fluid bearing with respect to the stator 50a. A method,
The rotating electrode 21 having the accommodating portion 28 for accommodating the liquid material is electrically connected to the rotor 40a and fixed to rotate integrally, while the conductive liquid material 22 is accommodated in the accommodating portion 28. The voltage, electrical resistance, and capacitance between the fixed electrode 23 and the stator 50a in a state where the fixed electrode 23 is immersed in contact with the rotating electrode 21 in the conductive liquid material 22 accommodated together. The above-mentioned problem is solved by providing a bearing inspection method characterized in that the contact state is determined based on any of the above.

A rotor 40 having a shaft (rotating shaft 45) is supported in an insulated state by a sliding bearing in a thrust direction with respect to a stator 50 having a sleeve 52 through which the shaft (rotating shaft 45) is inserted. And a bearing inspection method for determining a contact state as to whether or not the shaft (rotating shaft 45) and the sleeve 52 are in contact with each other in a motor supported by a fluid bearing in a radial direction,
The rotating electrode 21 having the accommodating portion 28 for accommodating the liquid substance is electrically connected to the rotor 40 and fixed to rotate integrally, while the accommodating liquid 28 is accommodated in the accommodating portion 28. The voltage, electrical resistance, and capacitance between the fixed electrode 23 and the stator 50 in a state where the fixed electrode 23 is immersed in contact with the rotating electrode 21 in the conductive liquid material 22 accommodated together. The above-mentioned problem is solved by providing a bearing inspection method characterized in that the contact state is determined based on any of the above.

An assembly step of assembling the rotor 40a and the stator 50a so that the rotor 40a is rotatably supported by the stator 50a via a fluid bearing;
After the assembling process, the rotating electrode 21 having the accommodating portion 28 for accommodating the liquid substance is electrically connected to the rotor 40a and fixed so as to rotate integrally. The voltage between the fixed electrode 23 and the stator 50a in the state in which the fixed electrode 23 is immersed in contact with the rotating electrode 21 in the conductive liquid material 22 accommodated and contained in the conductive liquid material 22 By providing a method of manufacturing a motor having a bearing inspection step of determining whether or not the rotor 40a and the stator 50a are in contact with each other based on either resistance or capacitance Solve the above problems.

Further, a rotor 40 having a shaft (rotating shaft 45) and a stator 50 having a sleeve 52 inserted through the shaft (rotating shaft 45) are arranged in a thrust direction with respect to the stator 50. An assembly process for assembling to be supported in an insulated state via a plain bearing and rotatably supported in a radial direction via a fluid bearing;
After the assembling process, the rotating electrode 21 having the accommodating portion 28 for accommodating the liquid substance is electrically connected to the rotor 40 and fixed so as to rotate integrally. The voltage between the fixed electrode 23 and the stator 50 in the state in which the fixed electrode 23 is immersed in contact with the rotating electrode 21 in the conductive liquid material 22 accommodated and contained in the conductive liquid material 22. And a bearing inspection step for determining a contact state as to whether or not the shaft (rotating shaft 45) and the sleeve 52 are in contact with each other based on either resistance or capacitance. This solves the above problem.

The bearing inspection method and the motor manufacturing method according to the present invention are configured as described above.
(1) It is not necessary to place an electrode or the like for measuring the motor's flying speed close to the rotor of the hydrodynamic bearing motor, and the floating speed of the hydrodynamic bearing motor is measured even if mechanical vibration occurs in the rotor. Is possible.
(2) Since a conductive liquid substance is interposed between the rotor and the fixed electrode of the fluid dynamic bearing motor, the load on the rotor is small, and the motor rotation speed is not reduced and the motor rotation is not stopped. In addition, it is possible to measure the floating rotational speed of the hydrodynamic bearing motor.
(3) Since the levitation speed of the hydrodynamic bearing motor can be accurately measured, it is not necessary to set an acceptance criterion value that is stricter than necessary, yield is improved, and defective products are not leaked.

  Embodiments of a bearing inspection method and a motor manufacturing method according to the present invention will be described with reference to the drawings.

  FIG. 1A is a half sectional view showing a schematic configuration when the bearing inspection method according to the present invention is applied to a hydrodynamic bearing motor using a slide bearing for supporting in the thrust direction. FIG. 1B is a half sectional view showing a schematic configuration when the bearing inspection method according to the present invention is applied to a fluid dynamic bearing motor using fluid dynamic pressure bearings in both the thrust and radial directions. FIG. 2 is a schematic circuit diagram in an embodiment of the bearing inspection method according to the present invention. FIG. 3 is a diagram showing the relationship between the rotational speed and the measured voltage in the embodiment of the bearing inspection method according to the present invention. FIG. 4A is a flowchart showing an outline of a method for manufacturing a fluid dynamic bearing motor. 4B and 4C are diagrams for explaining the outline of the method of manufacturing the fluid dynamic bearing motor. Again, in the following description, the rotation shafts 45 and 45a (including the ring-shaped flange 201 in FIG. 1B) and the sleeves 52 and 52a (including the thrust plate 71a in FIG. 1B) are rotated. For the sake of convenience, the non-contact state is sometimes referred to as rising.

  From FIG. 1A and FIG. 1B, the rotating electrode 21 having the substantially cup-shaped accommodation portion 28 opened upward is rotated on the upper surface of the rotating shafts 45 and 45a of the hydrodynamic bearing motors 60 and 60a for inspecting the flying speed. It is fixed coaxially with the shafts 45 and 45a. As a method of fixing the rotary electrode 21 and the rotors 40 and 40a, the screw portion 27 is formed so as to stand on the bottom surface of the rotary electrode 21, and the screw portion 27 is formed in the screw shaft formed in the rotary shafts 45 and 45a. It is preferable to carry out by screwing to 49. The accommodation portion 28 of the rotating electrode 21 is filled with a predetermined amount of the conductive liquid material 22, and the accommodation portion 28 filled with the conductive liquid material 22 has a fixed electrode 23 having an outer dimension smaller than the inner circumference of the accommodation portion 28. Is inserted and fixed so as to be coaxial with the rotating electrode 21 and not to contact the rotating electrode 21. At this time, the fixed electrode 23 is fixed at a position where the fixed electrode 23 is immersed in the conductive liquid material 22 and the fixed electrode 23 and the bottom surface of the housing portion 28 are not in contact with each other even when the rotors 40 and 40a rotate and float. Position. The fixed electrode 23 is connected to the positive electrode of the DC power supply 24 via the variable resistor R, and the negative electrode (GND) of the DC power supply 24 is connected to the stators 50 and 50a of the fluid dynamic bearing motors 60 and 60a. A measurement terminal 25 is provided between the fixed electrode 23 and the variable resistor R. The measurement terminal 25 is connected to a positive electrode of a voltmeter 26 that is a measurement device, and a negative electrode of the voltmeter 26 is connected to GND. The value of the variable resistance R is the measured voltage obtained by the voltmeter 26 when the rotating shafts 45 and 45a are rotating in contact with the sleeves 52 and 52a, and the rotating shafts 45 and 45a are not in contact with the sleeves 52 and 52a. The voltage measured by the voltmeter 26 when rotating in a state is adjusted in advance to a value that produces a difference that can be easily determined (preferably the same resistance value as that of the conductive liquid material 22). The Although not shown, a rotational speed meter such as a tachometer is installed in the fluid bearing motors 60 and 60a to measure the rotational speeds of the rotors 40 and 40a of the fluid bearing motors 60 and 60a.

  According to the bearing inspection method of the embodiment, when the rotors 40 and 40a are fixed to the rotary shafts 45 and 45a and the rotors 40 and 40a rotate, the rotating electrode 21 and the fixed electrode 23 that rotate together with the rotors 40 and 40a cause the conductive liquid material 22 to flow. The conductive liquid material 22 is made of a conductive liquid or a paste, gel, or the like. Examples of the conductive liquid material 22 include water: 100 μS / cm (μS: Micro Siemens), dilute electrolyte: 1000 μS / cm, conductive grease: 5000 μS / cm, and the like. The coefficient of friction between the conductive liquid material 22 such as a liquid and the rotating electrode 21 and the fixed electrode 23 is the same as that of the rotors 40 and 40a in the case where the electrodes are brought into direct contact with the rotors 40 and 40a as in the prior art. It is much smaller than the coefficient of friction between the contact electrodes. Therefore, by interposing the conductive liquid material 22 between the rotating electrode 21 and the fixed electrode 23, the rotating method is faster than the contact type inspection method in which the electrodes are directly brought into contact with the conventional rotors 40 and 40a. The load applied to the children 40 and 40a is extremely small. Therefore, according to the bearing inspection method described above, it is possible to accurately measure the flying speed of the motor without causing a decrease in the motor speed or a motor rotation stop due to a load on the rotors 40 and 40a. .

  Furthermore, since there is a sufficient gap between the rotating electrode 21 and the fixed electrode 23, the rotating electrode 21 and the fixed electrode 23 do not come into contact with each other due to mechanical vibration of the motor.

  FIG. 2 shows a schematic circuit diagram in an embodiment of the bearing inspection method according to the present invention. In FIG. 2, the resistor R22 represents the electrical resistance of the conductive liquid material 22, the resistor R40 represents the electrical resistance of the rotors 40 and 40a, and the resistor R50 represents the electrical resistance of the stators 50 and 50a. The portion surrounded by a broken line shows a schematic equivalent circuit of the bearing portion of the fluid bearing motor 60, 60a. The resistor R55 indicates the electrical resistance of the lubricant 55 used in the fluid bearing, and the switch SW indicates When the rotary shafts 45, 45a and the sleeves 52, 52a are in contact with each other, the switch SW is equivalent to the closed state. When 45, 45a and the sleeves 52, 52a are in a non-contact state, the switch SW is equivalent to an open state.

  When electricity is supplied to predetermined terminals of the fluid dynamic bearing motors 60 and 60a, the rotors 40 and 40a rotate. When the rotational speed of the rotors 40, 40a is lower than the floating rotational speed, the rotary shafts 45, 45a rotate in contact with the sleeves 52, 52a, so that the switch SW is equivalent to the closed state, and the voltmeter 26 Represents a potential applied to the resistor R22, the resistor R40, and the resistor R50 as a measurement voltage.

  In addition, when the rotational speed of the rotors 40 and 40a is higher than the floating rotational speed, a fluid dynamic pressure is generated in the fluid bearing portion so as to float the rotors 40 and 40a, and the rotary shafts 45 and 45a have sleeves 52 and 52a. Rotates in a non-contact state. Therefore, the switch SW is equivalent to an open state, and the voltmeter 26 has a resistance R55 of the lubricant 55 between the rotary shafts 45 and 45a and the sleeves 52 and 52a in addition to the resistance R22, the resistance R40, and the resistance R50. The included potential is expressed as a measurement voltage.

  The measured voltage of the voltmeter 26 when the rotary shafts 45 and 45a are rotating in a non-contact state with the sleeves 52 and 52a is that the resistance R55 of the lubricant 55 is added to the rotary shafts 45 and 45a. Shows a value higher than the measured voltage of the voltmeter 26 when rotating in contact. In general, the resistance value of the resistance R40 of the rotor 40, 40a formed of metal, the resistance R50 of the stator 50, 50a, and the resistance R22 of the conductive liquid material 22 is several tens of kΩ, The resistance value of the resistor R55 of the lubricant 55 has a large value of about 1 MΩ. For this reason, the measured voltage when rotating in a non-contact state and the measured voltage when rotating in a contact state There is a large difference between them that can be easily discriminated. Therefore, it is possible to determine whether the hydrodynamic bearing motors 60 and 60a are rotating in a contact state or in a non-contact state from the value of the measured voltage of the voltmeter 26, and the rotation of a rotation speed meter (not shown) is possible. By reading the rotational speed at which the measured voltage value of the voltmeter 26 changes rapidly from the number, the floating rotational speed of the fluid dynamic bearing motors 60, 60a can be obtained. The rotor 40 rotates in a point contact with the thrust plate 71. However, since the thrust plate 71 has an insulating property, the above measurement method is not hindered.

  FIG. 3 shows the relationship between the rotational speed and the measured voltage in the embodiment of the bearing inspection method according to the present invention. Here, a hydrodynamic bearing motor 60 using a sliding bearing for supporting in the thrust direction is used as the hydrodynamic bearing motor to be measured, water is used as the conductive liquid material 22, the value of the variable resistance R is 500 kΩ, and the power source of the DC power source 24 is used. The voltage was 5V. From FIG. 3, the measured voltage shows a small value of about 0.3 V in the range where the rotational speed of the rotor 40 of the hydrodynamic bearing motor 60 is 250 rpm or less. This means that the rotating shaft 45 is rotating in contact with the sleeve 52. Moreover, in the range where the rotation speed of the rotor 40 is 300 rpm or more, the measured voltage shows a large value of about 3.5V. This means that the rotating shaft 45 rotates in a non-contact state with the sleeve 52. When the rotational speed of the rotor 40 is in the range of about 250 rpm to 300 rpm, the measurement voltage is rapidly increased or decreased. This means that the rotation shaft 45 repeats contact and non-contact with the sleeve 52, and the rotation of the rotation shaft 45 and the sleeve 52 from the rotation in the contact state to the rotation in the non-contact state. Number, or the number of rotations that shift from the rotation in the non-contact state to the rotation in the contact state, that is, the flying rotation number. Here, the pass / fail judgment reference value of the floating rotational speed of the fluid dynamic bearing motor 60 is set to a predetermined value, and whether or not the floating rotational speed obtained by the bearing inspection method satisfies the acceptance judgment reference value. By determining, the floating rotational speed of the fluid dynamic bearing motor 60 can be inspected.

  Next, an embodiment of a method for manufacturing a fluid dynamic bearing motor according to the present invention will be described. FIG. 4A is a flowchart showing an outline of a method for manufacturing a fluid dynamic bearing motor. The hydrodynamic bearing motor manufacturing method includes a hydrodynamic bearing motor manufacturing process having a hydrodynamic bearing motor assembly process (step S43) and a hydrodynamic bearing motor inspection process (step S44) as shown in FIG. 4A.

  Next, an outline of a more specific manufacturing method will be described with reference to FIGS. 4B and 4C using a fluid dynamic bearing motor 60a using a fluid dynamic pressure bearing in both the thrust and radial directions. First, as shown in FIG. 4B (a), a sleeve 52a having a predetermined shape and a base plate 51a constituting the stator 50a of the hydrodynamic bearing motor 60a are manufactured by cutting or the like. At this time, a radial dynamic pressure groove 56 is formed on the inner peripheral surface of the sleeve 52a. (However, the radial dynamic pressure groove 56 is not shown in FIGS. 4B and 4C.) Separately, the rotary shaft 45a having a predetermined shape and the ring-shaped flange 201 constituting the rotor 40a are provided. Prepared by cutting or the like. At this time, a screw hole 49 is formed at the upper end of the rotating shaft 45a coaxially with the rotating shaft 45a, and a radial dynamic pressure groove 48 having a predetermined shape is formed on the outer peripheral surface of the rotating shaft 45a. A thrust dynamic pressure groove (not shown) having a predetermined shape is formed on the upper surface and the lower surface of the ring-shaped flange 201.

  Then, as shown in FIG. 4B (b), the sleeve 52a is press-fitted and fixed at a predetermined position of the base plate 51a, and the rotary shaft 45a is press-fitted and fixed in the hole formed at the center of the ring-shaped flange 201.

  Next, as shown in FIG. 4B (c), the rotating shaft 45a to which the ring-shaped flange 201 is press-fitted and fixed is inserted into the sleeve 52a in a rotatable state.

  Next, as shown in FIG. 4C (a), the thrust plate 71a is press-fitted and fixed at a predetermined position of the base plate 51a. As a result, the ring-shaped flange 201 is movably enclosed between the sleeve 52a and the thrust plate 71a.

  Next, as shown in FIG. 4C (b), a lubricant 55 such as oil is filled in the gap between the rotary shaft 45a and the ring-shaped flange 201 and the sleeve 52a and the thrust plate 71a surrounding them. Further, the core 54 around which the coil 53 is wound is fixed to the extending portion 57 provided on the outer peripheral portion of the lower portion of the sleeve 52a. Thereby, the stator 50a attached so that the rotating shaft 45a which is a part of the rotor 40a is rotatable is formed. The above corresponds to step S42 in FIG. 4A.

  Separately from this, the hub 44 constituting the rotor 40a of the hydrodynamic bearing motor 60a is manufactured by cutting or the like into a substantially cup shape having a predetermined dimension. At this time, a hole for fixing the rotation shaft 45 a is formed at the center of the substantially cup-shaped opening of the hub 44. Further, a ring-shaped yoke 46 is fixed to the bottom surface of the hub 44 so as to be coaxial with the hub 44 and along the outer periphery of the hub 44, and a permanent magnet 47 is bonded and fixed to the inner peripheral surface of the yoke 46. The above corresponds to step S41 in FIG. 4A.

  Then, as shown in FIG. 4C (c), the upper end of the rotating shaft 45a is press-fitted and fixed into the hole at the center of the opening of the hub 44 to which the respective members are fixed. As a result, as shown in FIG. 4C (d), a fluid dynamic bearing motor 60a using a fluid dynamic pressure bearing is produced in both the thrust and radial directions composed of the rotor 40a and the stator 50a. The above corresponds to step S43 in FIG. 4A.

  Next, the fluid bearing motors 60 and 60a completed in the fluid bearing motor inspection step (step S44) are inspected. The inspection items of the hydrodynamic bearing motors 60 and 60a are diverse, such as torque inspection and dimensional inspection. One of the inspection items is a floating rotational speed inspection as a bearing inspection process. The floating rotational speed inspection of the fluid dynamic bearing motors 60 and 60a is performed using the bearing inspection method described above. By performing the floating rotational speed inspection of the fluid bearing motors 60 and 60a using the bearing inspection method described above, the floating rotational speed of the fluid bearing motors 60 and 60a can be accurately measured, and the optimum acceptance criterion can be obtained. Based on this, it is possible to perform a highly reliable inspection of the levitation speed.

  Next, it is packed after a cleaning process (step S45) for checking and cleaning the dirt of the motor (step S46).

  From the above, according to the bearing inspection method of the present invention, the conductive liquid material 22 is interposed between the rotating electrode 21 and the fixed electrode 23 fixed to the rotor of the fluid dynamic bearing motor, so that Since the load can be made extremely small, the motor rotation speed is not reduced and the motor rotation is not stopped, and the floating rotation speed of the fluid dynamic bearing motor can be accurately inspected.

  In addition, according to the motor manufacturing method of the present invention, the floating rotational speed of the fluid bearing motor can be accurately measured by using the bearing inspection method of the present invention for the floating rotational speed inspection in the fluid bearing motor inspection process. This makes it possible to perform a highly reliable inspection of the flying speed using the optimum acceptance criterion value. Thereby, the manufacturing yield of the hydrodynamic bearing motor is improved and the outflow of defective products does not occur.

  In the embodiment of the present invention, the example in which the levitation speed is measured by changing the measurement voltage is used. However, the present invention is not limited to this example. You may measure a rotation speed. In the embodiment of the present invention, water is used as the conductive liquid material 22. However, the conductive liquid material 22 is a liquid having a conductivity, such as mercury or conductive grease, a paste, or a gel. Substances can be used. Further, in the embodiment of the present invention, the description has been made using the fluid dynamic bearing motor 60 using the slide bearing for supporting in the thrust direction and the fluid dynamic bearing motor 60a using the fluid dynamic pressure bearing in both the thrust and radial directions. The present invention can be applied to other fluid dynamic bearing motors, and can be modified without departing from the scope of the present invention. Further, the radial dynamic pressure groove and the thrust dynamic pressure groove may be provided on both the stator side and the rotor side, or may be provided on either the stator side or the rotor side.

It is a half sectional view showing a schematic structure when the bearing inspection method according to the present invention is applied to a hydrodynamic bearing motor using a slide bearing for supporting in the thrust direction. It is a half sectional view showing a schematic structure when the bearing inspection method according to the present invention is applied to a fluid dynamic bearing motor using fluid dynamic pressure bearings in both the thrust and radial directions. It is a typical circuit diagram in the example of the bearing inspection method concerning the present invention. It is a figure which shows the relationship between the rotation speed and measured voltage in the Example of the bearing test | inspection method which concerns on this invention. It is a flowchart which shows the outline of the manufacturing method of a fluid dynamic bearing motor. It is a figure explaining the outline of the manufacturing method of a fluid dynamic bearing motor. It is a figure explaining the outline of the manufacturing method of a fluid dynamic bearing motor. It is sectional drawing which shows the outline of a structure of the fluid bearing motor which used the sliding bearing in the thrust direction. It is sectional drawing which shows the outline of a structure of the fluid bearing motor which used the fluid dynamic pressure bearing in the thrust direction and the radial direction. It is a figure explaining the conventional bearing inspection apparatus.

Explanation of symbols

21 Rotating electrode
22 Conductive liquid material
23 Fixed electrode
24 DC power supply
25 Measuring terminal
26 Voltmeter
27 Screw part
28 containment
40, 40a rotor
45, 45a Rotating shaft
50, 50a Stator
52, 52a Sleeve
55 Lubricant
60, 60a Fluid bearing motor

Claims (11)

A bearing inspection method for determining a contact state between the rotor and the stator of a motor including a rotor, a stator, and a fluid bearing,
A rotating electrode that is electrically connected to the rotor and rotates integrally;
A fixed electrode disposed in non-contact with the rotating electrode;
A conductive liquid material interposed between the rotating electrode and the fixed electrode;
Through to determine the contact state substantially based on any of the voltage, electrical resistance, capacitance between the fixed electrode and the stator ,
The rotor has a shaft formed with a screw hole at one end,
The rotating electrode is formed with a screw portion,
A bearing inspection method , wherein the rotating electrode is fixed to the rotor by screwing the screw portion into the screw hole . A bearing inspection method for determining a contact state as to whether or not the rotor and the stator are in contact with each other in a motor in which the rotor is rotatably supported by a fluid bearing with respect to the stator,
A rotating electrode having a receiving portion for storing a liquid substance is electrically connected to the rotor and fixed so as to rotate integrally, while the conductive liquid material is received and stored in the receiving portion. In a state where the fixed electrode is immersed in a conductive liquid substance in a non-contact manner with the rotating electrode, the contact state is determined based on one of the voltage, electrical resistance, and capacitance between the fixed electrode and the stator. Judgment ,
The rotor has a shaft formed with a screw hole at one end,
The rotating electrode is formed with a screw portion,
A bearing inspection method , wherein the rotating electrode is fixed to the rotor by screwing the screw portion into the screw hole . The rotor bearing inspection method according to claim 1 or 2, characterized in that it is supported by the fluid bearing in a radial direction is supported by the sliding bearings in the thrust direction with respect to the stator. The fixed electrode is connected to one pole of a power source through a resistor,
Bearing inspection method according to any one of claims 1 to 3, the other pole of said power source, characterized in that connected to the stator. Resistance value of the resistor, to claim 4, characterized in that it is adjusted to the resistance value substantially the same value between the rotating electrode and the fixed electrode via the conductive liquid material The bearing inspection method described. The conductive liquid material, water, a dilute electrolyte, the conductive grease, the bearing inspection method according to any one of claims 1 5, characterized in that either the mercury. Method for manufacturing a motor which comprises a bearing inspection method according to any one of claims 1 to 6. A method of manufacturing a hydrodynamic bearing motor comprising a rotor, a stator, and a hydrodynamic bearing,
Rotor assembly process for assembling rotor, stator assembly process for assembling stator, fluid bearing motor assembly process for assembling fluid bearing motor using assembled rotor and stator, and assembled fluid bearing motor An inspection process for inspecting the number of rotations of
The inspection process includes
Apart from the motor to be inspected, preparing a rotating electrode, and a fixed electrode arranged facing the rotating electrode in the direction of the rotation axis;
Fixing the rotating electrode to the end of the rotor substantially coaxially with the rotating shaft so that the rotating electrode is electrically connected to the rotor and rotates integrally;
After determining whether or not the rotor and the stator are in contact with each other based on any of the voltage, electrical resistance, and capacitance between the fixed electrode and the stator, the rotating electrode Removing from the rotor. A method of manufacturing a hydrodynamic bearing motor. 9. The inspection step includes inspecting whether or not the rotor is floating with respect to the stator when the motor to be inspected rotates at a predetermined rotational speed. Manufacturing method for a hydrodynamic bearing motor. 10. The method of manufacturing a hydrodynamic bearing motor according to claim 8, wherein the inspection step is performed in a state where a conductive liquid material is interposed between the fixed electrode and the rotating electrode. 10. The rotor has a non-through hole formed substantially coaxially with the rotation center at the end,
The rotating electrode has a convex portion at the end.
The said inspection process is performed in the state fixed so that the said rotating electrode might rotate integrally with the said rotor by fitting the said convex part to the said non-through-hole. A method for manufacturing a fluid dynamic bearing motor according to any one of the above.

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