JP3895255B2 - Fluid bearing inspection method and inspection apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an inspection method and an inspection device for a fluid dynamic bearing such as a dynamic pressure bearing used for a high-precision spindle such as a hard disk device.
[0002]
[Prior art]
With the miniaturization and high recording density of hard disk devices, the precision requirements for bearings that support magnetic disks have become extremely strict, making it difficult for rolling bearings to handle them. Therefore, it is shifting to fluid bearings such as dynamic pressure bearings. In the hydrodynamic bearing used for this type of spindle device, it is also necessary to support an axial load. As a support type of the axial load, there is a type of sliding contact at the spherical surface portion of the shaft end, but dynamic pressure support is also adopted for the axial load in terms of durability and function. For example, a fluid bearing having a radial bearing portion and a thrust bearing portion that support a rotating shaft in the bearing body is used. In a fluid bearing used for such a high-precision spindle, it is desired to inspect before shipping in the production process.
As a device for measuring the rotational accuracy and dynamic torque of small and high-precision bearings used in hard disk devices, etc., for deep groove ball bearings, the inner ring is attached to the drive shaft and driven, and the holder is attached to the outer ring. There has been proposed one that measures displacement in both radial and axial directions while applying an axial load with the holder being in a displaceable state (for example, Patent Document 1). The axial preload is applied while allowing displacement in each direction via a hydrostatic gas bearing.
In general, when inspecting the run-out and rotational torque of a small bearing, a pulley instead of a weight is attached to a rotary shaft and driven to rotate through a transmission member such as a thread.
Among the hydrodynamic bearings, those that make sliding contact with the spherical portion at the shaft end to support the axial load have been proposed in which various measurements are performed while preloading the axial load is applied.
[0003]
[Patent Document 1]
JP 2001-194270 A
[0004]
[Problems to be solved by the invention]
In a hydrodynamic bearing having a radial bearing portion and a thrust bearing portion that support a rotating shaft in a bearing body, particularly in a type in which one end of the rotating shaft protrudes from the bearing body, a deep groove ball bearing inspection device disclosed in Patent Document 1 As described above, it is not possible to adopt a drive type in which the inner ring is attached to the drive shaft to give rotational drive. In addition, since a hydrodynamic bearing having a radial bearing portion and a thrust bearing portion needs to measure the flying height in the axial direction of the rotating shaft, the conventional driving method while applying preload in the axial direction cannot be adopted. In the conventional method of driving via a thread and pulley, an excessive radial load is applied due to the thread tension, so accurate measurement cannot be performed. In addition, each of the conventional drive systems has a problem that it is difficult to apply to a bearing alone, that is, a bearing that is not mounted on a bearing built-in device such as a motor. In particular, in the measurement of rotational torque, it took time until the rotational torque entered a steady state, and the efficiency was poor, so that it could not be used in the production process.
[0005]
An object of the present invention is a fluid dynamic bearing that has a radial bearing portion and a thrust bearing portion, and can accurately and quickly inspect inspection items such as flying height and rotational torque according to a load during use in a single bearing state. An inspection method and an inspection apparatus are provided.
[0006]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, a fluid bearing inspection method according to the present invention corresponds to a bearing load in a method of inspecting a fluid dynamic bearing having a radial bearing portion and a thrust bearing portion that support a rotating shaft in a bearing body. In this method, a heavy dummy disk is attached to the rotating shaft of the bearing to be inspected, and the dummy disk is rotated by blowing compressed air on the outer periphery of the disk, and the inspection target items of the bearing to be inspected are measured. In the fluid pressure bearing, for example, one end of a rotating shaft projects from a bearing body.
According to this method, rotation is performed by blowing compressed air on the outer periphery of the dummy disk attached to the rotating shaft of the bearing to be inspected, so that only rotating force is applied to the rotating shaft without applying axial or radial external force. be able to. For this reason, the measurement value is not affected by the external force accompanying the driving force application, and it is possible to accurately measure various inspection items such as the flying height and rotational torque of the bearing to be inspected. In particular, it is possible to measure the flying height of a single bearing, which was impossible in the past. In addition, because it is rotated by compressed air, connection and disconnection of the rotation transmission system is unnecessary, and the dummy disk is prepared by attaching it to the bearing to be inspected while inspecting other bearings before inspection. When a large number of bearings are inspected sequentially, the attachment / detachment time of the dummy disk does not affect the inspection time. For these reasons, individual bearings can be inspected quickly, and this inspection method can be employed in the bearing production process.
The term “fluid bearing” in this specification refers to a general bearing that supports a rotating shaft by interposing a fluid such as liquid or gas and obtains a friction reducing effect mainly by the intervening fluid. Includes pressure bearings, other plain bearings, and hydrostatic bearings.
[0007]
A fluid bearing inspection apparatus according to the present invention is an apparatus for inspecting a fluid dynamic bearing having a radial bearing portion and a thrust bearing portion that support a rotating shaft in a bearing body, and a bearing that supports a bearing to be inspected by a portion of the bearing body. Inspection of the installation table, a dummy disk that is detachably attached to the rotating shaft of the bearing to be inspected, a driving air nozzle that blows compressed air on the outer periphery of the dummy disk, and rotation of the bearing to be inspected Measuring means for measuring the subject matter.
According to the inspection apparatus having this configuration, the fluid bearing inspection method according to the method of the present invention can be carried out, and the above-described functions and effects of the inspection method can be obtained.
[0008]
The dummy disk may have at its center a chuck that can be opened and closed and is detachably attached to the rotating shaft of the bearing to be inspected. When the dummy disk is provided with a chuck that can be opened and closed as described above, the dummy disk can be easily attached to and detached from the rotating shaft.
[0009]
The dummy disk may have longitudinal grooves along the axial direction at a plurality of locations on the outer peripheral surface in the circumferential direction. When the vertical groove is provided, the resistance to the compressed air increases, and the rotational speed increase time up to the rated rotational speed can be shortened. Further, the longitudinal groove along the axial direction increases only the rotational driving force by the blown compressed air, but does not give lift, and thus does not adversely affect the measured value. This vertical groove is effective in increasing the reverse rotational force even when compressed air is blown in the braking direction of the dummy disk.
[0010]
In the present invention, a braking air nozzle that blows compressed air so as to rotate in the direction opposite to the rotation direction by the driving air nozzle may be provided on the outer peripheral portion of the dummy disk.
The dummy disk after the measurement is inertially rotated, and it takes time until the dummy disk stops completely. By blowing air from the braking air nozzle in the direction opposite to the driving air after the measurement is completed, the dummy disk can be stopped in a short time, thereby further reducing the inspection time. The direction of the driving air nozzle may be variable, and the compressed air may be blown in the reverse direction from the driving air nozzle. However, in the case of an inspection device for a small bearing, the nozzle direction is more variable. The configuration is simpler if the driving air nozzle and the braking air nozzle are provided separately.
[0011]
In the present invention, it is preferable that the driving air nozzle has a blowing position substantially at the center in the thickness direction on the outer peripheral surface of the dummy disk, and the blowing direction is a direction parallel to the disk surface. The braking air nozzle may have a direction in which the blowing direction is inclined with respect to the disk surface.
If the drive air blowing position is approximately the center in the thickness direction of the dummy disk and the blowing direction is parallel to the disk surface, only the rotational force can be applied without giving lift to the dummy disk. The flying height can be measured with high accuracy. Since measurement is not performed during braking, the blowing direction may be any direction that can be braked, and there is no problem even if it is oblique. If the blowing direction of the braking air is oblique, the braking air can be blown over a wide surface and can be stopped more quickly.
[0012]
In this invention, the drive air pressure control for increasing the pressure of the compressed air blown from the drive air nozzle as the difference between the target rotation speed and the actual rotation speed of the dummy disk increases in the compressed air supply system of the drive air nozzle Means may be provided. By providing such a drive air pressure control means, the pressure of the compressed air becomes strong at the rise from the stop state, the rotation rapidly increases, and the rotation speed reaches the vicinity of the target rotation speed that is set to the rated rotation speed or the like. If it raises, the pressure of compressed air will become weak and it will become possible to maintain a target rotational speed automatically within the substantially fixed range at the time of a test | inspection. Therefore, measurement can be performed with high accuracy in a short time.
[0013]
In the present invention, the bearing mounting base is composed of a stationary base and a rotary base that is rotatably supported by the stationary base via a hydrostatic bearing and can grip the bearing body of the bearing to be inspected. As another example, a torque measuring means for detecting the rotational torque of the bearing to be inspected from a co-rotating force acting between the rotating table and the stationary table may be provided.
As described above, since the rotational torque is detected from the co-rotation force of the turntable, the rotational torque of the bearing to be inspected can be detected with high accuracy. In addition, by using both the air drive system and the mechanism that detects rotational torque using the hydrostatic bearing, the flying height and rotational torque can be measured simultaneously without affecting each other's measured values. It becomes possible.
[0014]
In the present invention, as one of the detecting means, there is provided a flying height measuring means for measuring a flying height at which the rotating shaft of the bearing to be tested floats with respect to the bearing body, and the flying height measuring means is a rotation center of the dummy disk. It is good also as what has a displacement meter probe which detects the displacement between a dummy disc and a probe facing the vicinity.
The shaft end of the rotating shaft of the bearing to be inspected is generally formed with a lathe machining center hole or a mounting tap hole, and measurement cannot be performed with the displacement gauge probe facing the shaft end of the rotating shaft. However, the flying height can be measured by making the displacement meter probe face the dummy disk attached to the rotating shaft as described above.
[0015]
When such a displacement meter probe is used, a probe up / down moving mechanism for moving the displacement meter probe up / down relative to the dummy disk may be provided. This probe vertical movement mechanism has a stroke that can be raised to a predetermined standby height position at which the displacement meter probe does not interfere with the dummy disk when the test bearing is attached to or detached from the bearing mount. Further, as a means for controlling the probe vertical movement mechanism, a probe raising / lowering control means for controlling the displacement meter probe at a predetermined interval with respect to the dummy disk before bearing inspection is provided.
When a dummy disk is attached to the rotating shaft of the bearing to be inspected, a slight variation may occur in the mounting position accuracy of the dummy disk in the axial direction. For such variations in mounting position accuracy, the probe vertical movement mechanism and the probe lifting / lowering control means automatically adjust the height position of the displacement meter probe with respect to the dummy disk, and the axial position of the dummy disk is adjusted. The deviation is cancelled. For this reason, the flying height measurement by the flying height measuring means can be accurately performed.
[0016]
In the present invention, one displacement meter probe may be provided on the extension line of the rotation center of the bearing to be inspected. When the displacement probe is opposed to the extension line of the center of rotation, the inclination of the dummy disk does not affect the measurement accuracy, and high-accuracy flying height measurement with few errors can be performed.
[0017]
A plurality of displacement meter probes may be arranged at positions symmetrical to each other with respect to the rotation center of the bearing to be inspected. In the case of this configuration, by calculating and averaging the detection signals output from each displacement meter probe when measuring the flying height, it is possible to cancel the error at each detection location due to the inclination of the dummy disk, More accurate measurement is possible.
[0018]
In the present invention, the bearing to be inspected may be a dynamic pressure bearing, and the magnetic disk in the magnetic disk device may be attached to the rotating shaft. Bearings used in magnetic disk devices are required to have very high precision in accordance with miniaturization and recording density. In addition, when a dynamic pressure bearing is used as a bearing of a magnetic disk device, a bearing having a radial bearing portion and a thrust bearing portion is required, and the flying height in the thrust bearing portion is required to be highly accurate for stable shaft rotation. The Moreover, since it is a small-sized and low-cost mass-produced product, it is required to perform inspection quickly. According to the fluid bearing inspection device of the present invention, it can be satisfied even with such strict requirements on accuracy and measurement time.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a front view showing the entirety of a fluid dynamic bearing inspection apparatus, and FIG. 3 is a partially enlarged front view showing a part thereof. As shown in FIG. 3, the fluid bearing inspection apparatus is an apparatus for inspecting a bearing 40 to be inspected made of a fluid bearing, and a bearing mounting base 1 that supports the bearing 40 to be inspected by a portion of a bearing body 41; A dummy disk 2 that is detachably attached to the rotating shaft 42 of the bearing 40 to be inspected, a driving air nozzle 31 that blows compressed air for imparting rotation to the outer peripheral portion of the dummy disk 2, and the bearing 40 to be inspected in a rotating state. Measuring means 7 and 15 for measuring the items to be inspected.
[0021]
As shown in FIG. 11, the bearing 40 to be inspected is a combined fluid bearing having a radial bearing portion 43 and a thrust bearing portion 44 that support a rotating shaft 42 in a bearing body 41, for example, a hydrodynamic bearing. It is. Both the radial bearing portion 43 and the thrust bearing portion 44 are dynamic pressure bearings. These dynamic pressure bearings are of the type having, for example, herringbone grooves, and oil is sealed inside as a dynamic pressure applying fluid.
In the bearing 40 to be inspected in the figure, the rotating shaft 42 has a flange 42a, thrust bearing portions 44 are formed on both surfaces of the flange 42a, and a plurality of locations separated in the axial direction (in the illustrated example, 2). A radial bearing portion 43 is provided at a location). The flange 42 a is provided at the inner end of the rotating shaft 42, and the outer end 42 b of the rotating shaft 42 protrudes from the bearing body 41. The bearing body 41 includes a sleeve 45 fitted on the outer periphery of the rotary shaft 42, a cylindrical housing 46 fitted with the sleeve 45 on the inner circumference, and a thrust plate 47 that covers one end of the housing 46. The flange 42 a of the rotating shaft 42 is interposed between the inner end of the sleeve 45 and the thrust plate 47. The sleeve 45 is made of a sintered alloy or the like that can contain oil. Following the sleeve 45, a ring-shaped seal member 48 is provided in the housing 46. A herringbone groove (not shown) constituting a dynamic pressure bearing serving as the radial bearing portion 43 is provided on the inner diameter surface of the sleeve 46 or the outer diameter surface of the rotary shaft 42. Herring horn grooves (not shown) constituting a dynamic pressure bearing serving as the thrust bearing 44 are provided on the end face of the sleeve 45 and the thrust plate 47, or on both faces of the flange 42a. The sleeve 45 and the housing 46 may be configured as an integral part.
The bearing to be inspected 40 composed of the hydrodynamic bearing is supported by the thrust bearing portion 44 so as to float in the axial direction from the bottom surface of the thrust plate 47 by the dynamic pressure of the sealed oil in the operating state. The sleeve 46 is supported so as to be located at the center. The bearing 40 to be inspected is incorporated in, for example, a hard disk device, and a magnetic disk is attached to the tip of the rotating shaft 42 together with a driving motor rotor.
[0022]
3 includes a stationary table 4 and a rotating table 6 that is rotatably supported by the stationary table 4 via a hydrostatic bearing 5 and can grip the bearing body 41 of the bearing 40 to be inspected. . As shown in the sectional view of FIG. 6, the turntable 6 includes a turntable main body 6a and a clamp tool 6b provided on the turntable main body 6a and gripping the bearing main body 41 from the outer periphery. The clamp tool 6b opens and closes a clamp by moving a plurality of clamp claws arranged in the circumferential direction in the radial direction of the turntable in synchronization.
The hydrostatic bearing 5 is configured to rotatably support a shaft-like rotor 53 in a bearing housing 51, and includes a radial bearing portion 5a and a thrust bearing portion 5b that support the rotor 53. The bearing housing 51 is divided into an outer housing 51a and a sleeve 52 fitted to the inner periphery thereof. The bearing housing 51 is provided with nozzles 55 and 56 for feeding compressed gas into the bearing gap between the radial bearing portion 5a and the thrust bearing portion 5b. The hydrostatic bearing 5 has a position in which the rotor 53 is vertical and the housing 51 is supported by the stationary base 4, and the rotor 53 is connected to the rotary base body 6 a of the rotary base 6 or is integrated. It has become. In the illustrated example, the turntable 6 serves as an upper flange of the rotor 53 and constitutes a bearing surface of the thrust upper bearing portion 5 b in the hydrostatic bearing 5.
[0023]
One of the measuring means 7 and 15 (FIG. 1) is a torque measuring means 7 for detecting the rotational torque of the bearing 40 to be inspected from the co-rotational force acting between the rotary base 6 and the stationary base 4. . The torque measuring means 7 includes a pulley 8 attached to the rotor 53 of the hydrostatic bearing 5, a thread 9 with one end fastened to the outer periphery of the pulley 8, and the rotation of the bearing 40 to be inspected from the tensile force applied to the thread 9. It is comprised with the load measuring device 10 which detects a torque. The other end of the yarn 9 is fixed to the detection unit 10 a of the load measuring device 10. The bearing installation base 1 and the torque measuring means 7 constitute a rotational torque inspection mechanism 11.
[0024]
As shown in FIG. 3, the dummy disk 2 has a chuck 22 that is detachably attached to a rotating shaft 42 of a bearing 40 to be inspected and that can be opened and closed. As shown in a plan view in FIG. 5A, longitudinal grooves 13 are formed along the axial direction at a plurality of locations on the outer peripheral surface of the dummy disk 2 in the circumferential direction. The vertical groove 13 is not limited to a semicircular shape in a plan view as shown in FIG. 5A, but may be a rectangular shape in a plan view as shown in FIG. The saw may have a sawtooth shape in plan view.
As shown in an enlarged cross-sectional view in FIG. 4, a plurality of the driving air nozzles 31 are provided at a predetermined interval in the circumferential direction so as to face the outer peripheral portion of the dummy disk 2. Further, a braking air nozzle 32 that blows compressed air so as to rotate in the direction opposite to the rotation direction by the driving air nozzle 31 is provided facing the outer peripheral portion of the dummy disk 2. A plurality of braking air nozzles 32 are also provided at predetermined intervals in the circumferential direction. The driving air nozzle 31 has a blowing position substantially at the center in the thickness direction on the outer peripheral surface of the dummy disk 2 and a blowing direction parallel to the disk surface. The braking air nozzle 32 has a blowing direction inclined with respect to the disk surface. The driving air nozzle 31 and the braking air nozzle 32 are both installed in a nozzle block 33 disposed on the outer peripheral side of the dummy disk 2. The nozzle block 33 is, for example, a ring-shaped member or a plurality of members arranged in the circumferential direction.
[0025]
In FIG. 1, an electropneumatic regulator 19 is a supply system device that supplies power to each part of the inspection device and supplies compressed air. Among them, in the supply system of compressed air to the drive air nozzle 31, the drive air that increases the pressure of the compressed air blown from the drive air nozzle 31 as the difference between the target rotational speed and the actual rotational speed of the dummy disk 2 increases. Control means 14 is provided. Although not shown, the air supply system for the compressed air supplied to the brake air nozzle 32 also includes a brake air control means for reducing the pressure of the compressed air blown from the brake air nozzle 32 as the actual rotational speed of the dummy disk 2 decreases. Is provided.
[0026]
Another one of the measuring means 7 and 15 is the flying height measuring means 15 that measures the flying height of the rotating shaft 42 of the bearing 40 to be inspected with respect to the bearing body 41. This flying height measuring means 15 has a displacement meter probe 16 that faces the vicinity of the center of rotation of the dummy disk 2 and detects the displacement between the dummy disk 2 and the probe 16 (FIG. 3). The displacement meter probe 16 is supported by a probe support member 34 and is moved up and down with respect to the dummy disk 2 by the probe up-and-down movement mechanism 17 of FIG. The nozzle block 33 is attached to the probe support member 34. The probe vertical movement mechanism 17 has a stroke that allows the displacement gauge probe 16 to rise to a predetermined standby height position where it does not interfere with the dummy disk 2 when the bearing 40 to be inspected is attached to or detached from the bearing mount 1. As means for controlling the probe vertical movement mechanism 17, probe elevation control means 18 for controlling the displacement meter probe 16 so as to maintain a predetermined interval with respect to the dummy disk 2 at the time of bearing inspection is provided. One displacement meter probe 16 is provided on the extension line of the rotation center of the bearing 40 to be inspected as shown in FIG. As a modified example, as shown in FIG. 10, a plurality (two in this case) of the displacement meter probes 16 may be arranged at positions symmetrical to each other with respect to the rotation center of the bearing 40 to be inspected.
[0027]
As shown in FIGS. 1 and 3, the nozzle block 33 is provided with a rotation detecting means 35 opposed to the dummy disk 2, and the rotation detecting means 35 allows the rotational speed of the rotating shaft 42 of the bearing 40 to be inspected. Detected. The rotation detection means 35 is composed of a photoelectric sensor, and detects a rotation by detecting a mark or groove provided on the surface of the dummy disk 2.
[0028]
As shown in a cross-sectional view in FIG. 7, the dummy disk 2 includes a disk body 21 and a collet chuck 22 provided at the center of the disk body 21 and capable of gripping the rotating shaft 42 of the bearing 40 to be inspected. Have. The chuck 22 is attached to the disc main body 21 and has a sleeve 23 having a conical guide surface 23a, and the inner peripheral surface 24a is fitted to the conical guide surface 23a of the sleeve 23 and moved axially. Is expanded and contracted, and the collet 24 that grips the rotating shaft 42 by the inner peripheral surface 24a, the elastic body 25 that urges the collet 24 toward the reduced diameter side in the axial direction, and the collet 24 is pivoted against the elastic body 25. And a release operation unit 26 for moving the direction to the diameter expansion side. The collet 24 has slits (not shown) along the axial direction for allowing expansion and contraction at a plurality of locations in the circumferential direction. The elastic body 25 consists of a disc spring. The release operation unit 26 includes a bolt 27 that is screwed into the collet 24, and a washer 28 that is interposed between the sleeve 23 and the bolt head portion 27a and receives one end of the elastic body 25.
[0029]
Next, a measurement method for measuring each inspection target item of the bearing 40 to be inspected by the inspection apparatus having this configuration will be described. First, the rotating shaft 42 of the bearing 40 to be inspected is prepared by mounting the dummy disk 2 with the collet chuck 22. The bearing 40 to be inspected with the dummy disk 2 mounted thereon is arranged on the turntable 6 of the bearing installation base 1. The arranged bearing to be inspected 40 is gripped by the clamp tool 6 b of the turntable 6. Thereafter, the height of the displacement meter probe 16 is adjusted by the probe vertical movement mechanism 17 and measurement is started as follows.
In the measurement, the dummy disk 2 is rotationally driven by blowing compressed air from the driving air nozzle 31 to the dummy disk 2. When the dummy disk 2 reaches the rated rotational speed and is stabilized, torque measurement by the torque measuring means 7 and flying height measurement by the flying height measuring means 15 are performed. When the measurement is completed, compressed air is blown from the braking air nozzle 32 to the dummy disk 2, and the dummy disk 2 is rotated in the direction opposite to the rotation direction by the driving air nozzle 31, thereby stopping the dummy disk 2.
[0030]
Since the rotation of the bearing 40 to be inspected is performed by blowing compressed air onto the dummy disk 2 attached to the rotating shaft 42, only the rotating force is applied to the rotating shaft 42 without applying an axial or radial external force. be able to. Therefore, the measurement value can be accurately measured with respect to the flying height and the rotational torque of the bearing 40 to be inspected without affecting the measurement value due to the external force accompanying the driving force application. In particular, it is possible to measure the flying height of a single bearing, which was impossible in the past. Further, since rotation with compressed air is required, connection and disconnection operations of the rotation transmission system are unnecessary, and the dummy disk 2 is attached to the bearing 40 to be inspected later while the other bearings 40 are being inspected. Can be installed and prepared. For this reason, when a large number of bearings are inspected sequentially, the attachment / detachment time of the dummy disk 2 does not affect the inspection time. Therefore, the inspection can be performed quickly, and this inspection method and inspection apparatus can be employed in the bearing production process.
[0031]
When the dummy disk 2 is rotated by the compressed air, it may be difficult to apply sufficient rotational force if the outer peripheral surface of the dummy disk 2 is a smooth surface. Since the longitudinal groove 13 (FIG. 5) along the axial direction is formed, the resistance against the compressed air is increased, and the rotation speed increase time up to the rated rotation speed can be shortened. Since the vertical groove 13 is along the axial direction, only the rotational driving force is increased to the dummy disc 2 by blowing compressed air, and no lift is given, and the vertical groove 13 adversely affects the measurement of the flying height. There is nothing. The vertical groove 13 is useful also when the dummy disk 2 is braked. Further, since the driving air nozzle 31 is sprayed at a substantially central position in the thickness direction on the outer peripheral surface of the dummy disk 2 and the spraying direction is parallel to the disk surface, this also allows the dummy disk Only rotational force can be applied to 2 without applying lift, and the flying height can be measured with high accuracy.
[0032]
The rotation of the dummy disk 2 is increased from a stopped state to a target rotation speed, for example, a rated rotation speed, and the rotation torque and the flying height are measured while rotating at the rated rotation speed. Stop after measurement. When performing such rotational driving, if the air jet pressure from the driving air nozzle 31 is constant, when the air pressure is set to a high pressure in order to shorten the inspection time, the rotation rise time is shortened, but at the time of measurement This makes it difficult to maintain the rated speed of the motor, and adversely affects measurement accuracy. That is, when the rated rotational speed is reached and the air pressure is suddenly reduced, the speed curve becomes wavy and does not fall to the rated rotational speed, and measurement is performed in this speed fluctuation state. In addition, if the air pressure at the time of increasing the rotation is decreased to increase the measurement accuracy, it is easy to maintain the rotation speed near the rated rotation speed, but the increase in the rotation speed until reaching the rated rotation speed is slow, and the inspection time is prolonged. End up.
Therefore, in this embodiment, the pressure of the compressed air from the drive air nozzle 32 is feedback-controlled by the drive air control means 14 according to the difference between the rotation speed of the dummy disk 2 detected by the rotation detection means 35 and the target rotation speed. Is controlled proportionally. As a result, the pressure of the compressed air increases when the rapid rotation rise at the time of start-up is required, and the pressure of the compressed air decreases when the rotation speed increases to near the rated rotation speed. It can be maintained within a certain range. Therefore, measurement can be performed with high accuracy in a short time.
[0033]
Further, since the dummy disk 2 is used, the following effects can be obtained with respect to the flying height measurement. That is, in general, the shaft end of the rotating shaft 42 of the bearing 40 to be inspected is formed with a center hole and a tapping hole for lathe machining, and measurement is performed with the displacement meter probe facing the shaft end of the rotating shaft 42. I can't. For this reason, conventionally, in the state of a hard disk device incorporating a bearing, the surface of the magnetic disk that is significantly offset from the center of rotation is detected to measure the flying height of the bearing, and the measurement accuracy is poor. However, in this embodiment, since the dummy disk 2 is attached to the rotating shaft 42, the displacement gauge probe 6 can be opposed to the dummy disk 2, and the flying height of the bearing 40 to be inspected is measured in the vicinity of the center of rotation. be able to. For this reason, the flying height can be detected with high accuracy.
[0034]
Since the dummy disk 2 is mounted by the collet chuck 22, it can be mounted without damaging the rotating shaft 42 of the bearing 40 to be inspected and without tilting the rotating shaft 42. Incidentally, as a conventional configuration for attaching the parts such as the dummy disk 2 to the rotating shaft 42, a fitting made of a soft metal or resin is provided in the fitting portion, and the rotating shaft is press-fitted into this. However, there are problems such as press-fitting on the rotating shaft, sticking of the bush material to the rotating shaft, lowering of the number of times of use, mounting accuracy, and holding force after mounting due to plastic deformation of the bush. In addition, there is a configuration in which the taper flange is pressed and fixed with a screw. In this case, however, there is a problem in that the balance in the rotational direction is lost due to the mass of the screw, and it takes time to mount. However, according to the chuck 22 of this embodiment, by pressing the bolt head 27a at the center of the chuck 22, the collet 24 opens as shown in FIG. 8, and the rotary shaft 42 can be inserted into and removed from the collet 24. When the center of the chuck is stopped while the rotating shaft 42 is inserted into the collet 24, the collet 24 is closed by the restoring force of the elastic body 25. For this reason, the dummy disk 2 can be easily attached to and detached from the rotating shaft 42 in a short time.
[0035]
When the dummy disk 2 is mounted on the rotary shaft 42 by the collet chuck 22, the dummy disk 2 hardly tilts when mounted due to its structure, but there may be a slight variation in the mounting position accuracy in the axial direction. This misalignment is canceled by the control of the probe lifting / lowering control means 18 performed after the bearing 40 to be inspected is installed on the turntable 6. That is, under the control of the probe lifting / lowering control means 18, the probe vertical movement mechanism 17 moves the displacement meter probe 16 up and down to adjust the distance between the upper surface of the central portion of the dummy disk 2 and the displacement meter probe 16 to a predetermined value. This cancels the axial displacement. Thereby, accurate measurement by the flying height measuring means 15 can be made possible.
As a specific operation, when the turntable 6 grips the bearing main body 41 of the bearing 40 to be inspected, the displacement meter probe 16 largely escapes upward from the dummy disk 2, but at the start of the subsequent measurement cycle, first the displacement gauge 16 is displaced. The meter probe 16 suddenly descends to a height at which it does not come into contact with the upper surface of the dummy disk 2, and thereafter, a detection signal from the displacement meter probe 16 is fed back to the probe lift control means 18 so that the distance from the disk upper surface is optimal. Slightly move up to this point and hold the height thereafter. The height position at this time is 0 point (reference position) for detecting the flying height.
[0036]
Since the dummy disk 2 is mounted on the rotating shaft 42 using the collet chuck 22, the inclination of the dummy disk 2 at the time of mounting is extremely small, but there is a slight inclination because of the manufacturing accuracy of the dummy disk 2 itself. To do. On the other hand, as shown in FIG. 10 as a modified example, when two displacement meter probes 16 are arranged at positions symmetrical to each other with respect to the rotation center of the bearing 40 to be inspected, By calculating and averaging the detection signals output from the respective displacement gauge probes 16 at the time of measurement, the inclination of the detection portion of the dummy disk 2 can be canceled, and more accurate measurement can be performed.
[0037]
The measurement of the rotational torque is performed based on the co-rotational force applied to the turntable 6 that holds the bearing body 41 of the bearing 40 to be inspected. That is, the co-rotation force of the bearing main body 41 accompanying the rotation of the rotating shaft 42 of the bearing 40 to be inspected is transmitted to the bearing main body 41-the rotary table 6-the pulley 8, and finally the torque measuring means as the pulling force of the yarn 9. 7 is detected by a load measuring instrument 10. As a result, highly accurate rotational torque measurement can be performed. As for the measurement of the rotational torque, there is a method of measuring the torsion of the rotational drive transmission body, but the delicate rotational torque at the time of high rotation of a small spindle unit such as a hard disk device cannot be measured by the torsion measurement.
[0038]
In this inspection apparatus, since the rotational drive system for rotating the dummy disk 2 with compressed air and the rotational torque inspection mechanism 11 using the static pressure bearing 5 are employed, the flying height measurement and the rotational torque measurement are performed mutually. Can be performed simultaneously without adversely affecting the measured values. Conventionally, the measurement of the flying height and the measurement of the rotational torque are performed in separate processes using an independent device because there is a concern that each measured value is adversely affected due to the difference in each rotational drive system. The measurement took a lot of time. According to this embodiment, since the flying height and the rotational torque can be measured simultaneously without adverse effects, the measurement time can be shortened.
[0039]
【The invention's effect】
The fluid dynamic bearing inspection method according to the present invention is a method in which a dummy disk having a weight corresponding to a bearing load is attached to a rotating shaft of a bearing to be inspected, and the dummy disk is rotated by blowing compressed air around the outer periphery of the disk. Since this is a method for measuring the inspection items of the bearing, the inspection items such as the flying height and the rotational torque according to the load during use are accurate for a fluid bearing having a radial bearing portion and a thrust bearing portion in the state of the bearing alone. Good and quick inspection.
The fluid dynamic bearing inspection apparatus according to the present invention includes a bearing mounting base for supporting a bearing to be inspected by a portion of a bearing body, a dummy disk that is detachably attached to a rotating shaft of the bearing to be inspected, and a rotation around the outer periphery of the dummy disk. A hydrodynamic bearing having a radial bearing portion and a thrust bearing portion is provided with a driving air nozzle for blowing compressed air for application and a measuring means for measuring the inspection object of the rotating bearing to be inspected. Inspection items such as flying height and rotational torque according to the load during use can be inspected accurately and quickly.
[Brief description of the drawings]
FIG. 1 is a front view of a fluid dynamic bearing inspection apparatus according to an embodiment of the present invention.
FIG. 2 is a side view of the inspection apparatus.
FIG. 3 is a partially broken front view showing an enlarged main part of the inspection apparatus.
FIG. 4 is a partial enlarged cross-sectional view of a nozzle block in the inspection apparatus.
5A is a partial plan view of a dummy disk in the inspection apparatus, FIG. 5B is a partial plan view showing another example of the dummy disk, and FIG. 5C shows still another example of the dummy disk. It is a partial top view.
FIG. 6 is a partially broken front view showing an enlarged portion of a hydrostatic bearing in the inspection apparatus.
FIG. 7 is a cross-sectional view showing a state in which the dummy disk is mounted on the rotating shaft of the bearing to be inspected in the inspection apparatus.
FIG. 8 is an explanatory view showing an attaching / detaching operation of the dummy disc to / from the rotating shaft of the bearing to be inspected.
FIG. 9 is a front view showing the positional relationship between the dummy disk and the displacement meter probe.
FIG. 10 is a front view showing a modification of the flying height measuring means in the inspection apparatus.
FIG. 11 is a sectional view of an example of a bearing to be inspected.
[Explanation of symbols]
1 ... Bearing installation stand
2… Dummy disk
4 ... Stationary stand
5 ... Hydrostatic bearing
6 ... turntable
7 ... Torque measuring means
13 ... Vertical groove
14 ... Driving air control means
15 ... Means for measuring the flying height
16. Displacement probe
17 ... Probe vertical movement mechanism
18: Probe lifting control means
21 ... Disc body
22 ... Chuck
23 ... Sleeve
23a ... Guide surface
24 ... Collet
24a ... inner peripheral surface
25. Elastic body
26 ... Release operation section
31 ... Air nozzle for driving
32 ... Air nozzle for braking
40 ... Bearing to be inspected
41 ... Bearing body
42 ... Rotating shaft

Claims (13)

  A method for inspecting a hydrodynamic bearing having a radial bearing portion and a thrust bearing portion supporting a rotating shaft in a bearing body, wherein a dummy disc having a weight corresponding to a bearing load is attached to the rotating shaft of the bearing to be inspected, and the dummy disc A method for inspecting a fluid compression bearing in which the inspection subject matter of the bearing to be inspected is measured while rotating the disk by blowing compressed air on the outer periphery of the disk.   An apparatus for inspecting a hydrodynamic bearing having a radial bearing portion and a thrust bearing portion that support a rotating shaft in a bearing body, the bearing mounting base for supporting the bearing to be inspected by a portion of the bearing body, and the rotating shaft of the bearing to be inspected A dummy disk that is detachably attached to the disk, a driving air nozzle that blows compressed air for imparting rotation to the outer peripheral portion of the dummy disk, and a measuring means that measures the inspection target items of the bearing under rotation. Fluid bearing inspection equipment.   3. The fluid bearing inspection apparatus according to claim 2, wherein the dummy disk has a chuck that can be opened and closed, which is detachably attached to a rotating shaft of the bearing to be inspected.   4. The fluid bearing inspection apparatus according to claim 2, wherein the dummy disk has longitudinal grooves along the axial direction at a plurality of locations on the outer peripheral surface in the circumferential direction. In any one of claims 2 to 4, the outer peripheral portion of the dummy disc, the fluid bearing to the rotating direction by the drive air nozzle provided with braking air nozzle blowing compressed air to rotate in the reverse direction Inspection equipment.   6. The driving air nozzle according to claim 5, wherein the blowing position is substantially the center in the thickness direction on the outer peripheral surface of the dummy disk, and the blowing direction is a direction parallel to the disk surface. A fluid bearing inspection device in which the attaching direction is inclined with respect to the disk surface. In any one of claims 2 to 6, the supply system of the compressed air of the drive air nozzle, as the difference between the target rotational speed and the actual rotation speed of the dummy disc is large, it is blown from the driving air nozzle squeeze A fluid dynamic bearing inspection device provided with driving air pressure control means for increasing air pressure. In any one of claims 2 to 7, the bearing mount base, a stationary stand, rotatably supported by possible rotation grip the bearing body of the test bearing via a hydrostatic bearing to the still stand A fluid bearing inspection apparatus provided with a torque measuring means for detecting the rotational torque of the bearing to be inspected from a co-rotational force acting between the rotating base and the stationary base as the inspection means.   9. The flying height measuring means for measuring a flying height of the rotating shaft of the bearing to be inspected with respect to the bearing main body as one of the detecting means according to claim 8, wherein the flying height measuring means is a rotation of a dummy disk. A fluid bearing inspection apparatus having a displacement meter probe for detecting displacement between a dummy disk and a probe facing the vicinity of the center.   10. The probe vertical movement mechanism for vertically moving the displacement meter probe with respect to the dummy disk according to claim 9, wherein the probe vertical movement mechanism interferes with the dummy disk when the displacement gauge probe is attached to or detached from the bearing mounting base of the bearing to be inspected. As a means to control the probe vertical movement mechanism, the displacement meter probe is controlled so as to have a predetermined interval with respect to the dummy disk before the bearing inspection. An inspection device for a fluid dynamic bearing provided with a probe lifting control means.   11. The fluid bearing inspection apparatus according to claim 9, wherein one displacement meter probe is provided on an extension line of a rotation center of the bearing to be inspected.   11. The fluid bearing inspection apparatus according to claim 9, wherein a plurality of displacement meter probes are arranged at positions symmetrical to each other with respect to a rotation center of the bearing to be inspected. In any one of claims 2 to 12, the inspection bearing a dynamic pressure bearing device for inspecting a fluid bearing in which the magnetic disk is mounted to the rotating shaft of the magnetic disk device.

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