JP2009281462A - Aerostatic journal bearing spindle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an aerostatic journal bearing spindle capable of easily correcting large unbalance which cannot be corrected by a conventional balance correction means. <P>SOLUTION: The aerostatic journal bearing spindle 1 is provided with a rotating part 2 rotated around the axial line O; a fixation part 10 for rotatably supporting the rotating part 2 via an aerostatic journal bearing 21 and aerostatic thrust bearings 22a, 22b; and a balance correction ring 31 fixed to the rotating part 2. The balance correction ring 31 is fixed to the rotating part 2 using a plurality of ring fixing screws 32, and rotated around the axial line O together with the rotating part 2. The balance correction ring 31 can change the radial fixation position by adjusting tightening amount of the ring fixing screws 32. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a static pressure gas bearing spindle, and in particular, includes a rotating part and a fixed part that supports the rotating part, and the rotating part is not in contact with the fixed part between the rotating part and the fixed part. The present invention relates to a hydrostatic gas bearing spindle in which a hydrostatic gas bearing that supports a shaft is formed.

  In the hydrostatic gas bearing spindle, the rotating part is not in contact with the fixed part by interposing a static pressure gas bearing formed by supplying pressurized gas between the minute gaps between the rotating part and the fixed part. Supported in state. Therefore, the friction loss in the bearing is small, and the heat generated when the rotating part rotates at high speed is small. In addition, high-accuracy and smooth rotational movement is possible, and as long as it is in a normal operating state, fatigue and wear of the material do not occur. Taking advantage of such characteristics, the static pressure gas bearing spindle is widely used as a high-precision spindle or a high-speed spindle.

  There are various sizes of hydrostatic gas bearing spindles ranging from a small type to a large type. In particular, a small hydrostatic gas bearing spindle is often operated at high speed. In a hydrostatic gas bearing spindle that enables high-speed and high-precision rotation, vibration during rotation due to unbalance is the main cause of deterioration in rotational accuracy. In an optical disk inspection device, a mastering device, and the like, vibration caused by imbalance not only deteriorates the rotational accuracy of the static pressure gas bearing spindle itself, but is also one of the causes of deterioration of the accuracy of the entire device. When there is an imbalance in the rotation axis, the higher the rotation speed, the greater the effect.

  In order to rotate the hydrostatic gas bearing spindle at high speed while maintaining high accuracy, balance correction is required. Conventionally, a balance correction method has been proposed in which the balance measurement device determines the unbalance position and the unbalance amount of the rotating shaft and corrects the balance by adding a balance correction weight or scraping the unbalance part. (For example, refer to Patent Documents 1 and 2).

  FIG. 6 is a schematic cross-sectional view showing a configuration of a static pressure gas bearing spindle provided with a conventional balance correcting means. As shown in FIG. 6, the static pressure gas bearing spindle 101 includes a rotating unit 102 that rotates about the axis O. The rotating portion 102 includes a cylindrical shaft portion 103, a disc-shaped thrust plate 104 that is joined to one end of the shaft portion 103 and has a diameter larger than that of the shaft portion 103, and the shaft portion 103 with respect to the thrust plate 104. A cylindrical small-diameter shaft portion 105 formed on the opposite side of the axis O direction and a table 106 that is joined to the other end portion of the shaft portion 103 and fixes a workpiece or a tool to the table surface 107 are included.

  The hydrostatic gas bearing spindle 101 includes a fixed portion 110 that rotatably supports the rotating portion 102. The fixed part 110 includes a housing 111, bearing sleeves 112 and 113, and a spacer 114. The outer peripheral surface of the shaft portion 103 is surrounded by the bearing sleeve 112. The bearing sleeves 112 and 113 are surrounded by the housing 111, and a spacer 114 is provided on the outer peripheral side of the thrust plate 104.

  Between the outer peripheral surface of the shaft portion 103 and the inner peripheral surface of the bearing sleeve 112, a static pressure gas journal bearing 121 that supports the rotating portion 102 at least in the radial direction is formed. Between the bearing sleeve 112 and the thrust plate 104 and between the bearing sleeve 113 and the thrust plate 104, hydrostatic gas thrust bearings 122a and 122b that support the rotating portion 102 at least in the axial direction are formed, respectively. . Pressurized gas is supplied to the static pressure gas journal bearing 121 and the static pressure gas thrust bearings 122 a and 122 b via the air supply path 123. Further, the gas flowing out from the static pressure gas journal bearing 121 and the static pressure gas thrust bearings 122a and 122b is discharged to the outside of the static pressure gas bearing spindle 101 via the exhaust passage 124.

  A motor rotor 117 is installed on the small-diameter shaft portion 105 of the rotating unit 102, and a motor stator 118 is installed on the motor cover 115 so as to surround the outer peripheral surface of the motor rotor 117. By supplying electric power to the motor stator 118, the rotating unit 102 is driven to rotate. The rotation angle of the rotating unit 102 is detected by a rotary encoder 119 in order to control the rotation.

In the static pressure gas bearing spindle 101 having the above-described configuration, a balance correcting ring 131 for scraping and removing the unbalanced portion is fixed to the rotating portion 102 by a ring fixing screw 132 as a balance correcting means of the rotating portion 102. Yes. Further, balance correction taps 134a and 134b, which are screw holes for attaching balance correction weights, are provided on the balance correction ring 131 and the table 106, respectively. After the assembly of the hydrostatic gas bearing spindle 101 is completed, balance correction is performed by adding a weight to the balance correction taps 134a and 134b, or by cutting an arbitrary position of the balance correction ring 131.
JP-A-9-170530 JP 2006-215347 A

  However, the range in which the balance can be corrected after the assembly of the hydrostatic gas bearing spindle is completed is small. Therefore, when the unbalance of parts to be assembled to the rotating part such as a motor rotor is large, the balance correction is insufficient and the large unbalance cannot be handled only by the mass of the weight added to the balance correction tap or the mass removed by removing the unbalance part. There is a case. As a countermeasure, generally, a rough balance correction is performed in advance before the assembly of the hydrostatic gas bearing spindle, and the balance correction is performed again after the assembly is completed.

  The problems here are an increase in man-hours that require two corrections, and a small mass of weight to be attached and a mass that can be scraped off. Further, in a small static pressure gas bearing spindle, the balance correction ring is also small, and the fixing range of the balance correction ring to the rotating portion is limited. As a result, the fixing of the balance correcting ring becomes unstable, and problems such as the inability to correct a large unbalance and the weakness to disturbance occur.

  Further, since the static pressure gas bearing spindle is used in a clean environment, the scattering of shavings often becomes a problem when performing balance correction work near the place of use. Therefore, the balance correction work which moves to another room is required, and a man-hour is required further.

  The present invention has been made in view of the above problems, and its main object is to provide a static pressure that can easily correct a large unbalance, which cannot be corrected by adding a balance correction weight or removing an unbalance portion. A gas bearing spindle is provided.

  A static pressure gas bearing spindle according to the present invention includes a rotating portion that rotates about an axis, a fixed portion that rotatably supports the rotating portion via a static pressure gas bearing, and a balance correction ring that is fixed to the rotating portion. Is provided. The balance correcting ring is fixed to the rotating portion using a plurality of ring fixing screws, and rotates around the axis together with the rotating portion. The balance correcting ring is provided such that the radial fixing position can be changed by adjusting the tightening amount of the ring fixing screw.

  Preferably, the balance correction ring is provided with an attachment portion capable of attaching a weight for adding a weight unbalance to the balance correction ring.

  Preferably, the rotating unit has one end that is one end in the axial direction and the other end that is the end opposite to the one end. The balance correcting ring is fixed to the rotating portion at least one of the one end side and the other end side of the static pressure gas bearing.

  Preferably, a groove portion is formed in the rotating portion. In a state where the balance correcting ring is fixed to the rotating portion, the tip end portion of the ring fixing screw is in contact with the inner surface of the groove portion. The inner surface of the groove and the contact surface of the ring fixing screw that contacts the inner surface are formed non-parallel to the axial direction and the radial direction.

  Preferably, the balance correcting ring is formed with a screw hole in a radial direction in which the ring fixing screw is screwed. With the balance correcting ring fixed to the rotating part, the center line of the screw hole is shifted in the axial direction with respect to the deepest part of the groove part.

  Preferably, the screw hole is formed so as to open to the outer peripheral side of the balance correcting ring. The rotating portion includes a thrust surface that is a surface facing the end surface of the balance correcting ring. The inner surface of the groove and the contact surface of the ring fixing screw are inclined with respect to the axial direction and the radial direction so as to approach the axial line in the radial direction as approaching the thrust surface in the axial direction. The center line of the screw hole is shifted to the side away from the axial thrust surface with respect to the deepest portion of the groove. When the ring fixing screw is screwed into the screw hole, the balance correcting ring moves in the axial direction in a direction in which the end surface approaches the thrust surface.

  Preferably, the balance correcting ring is formed with a screw hole into which the ring fixing screw is screwed in the axial direction. The hydrostatic gas bearing spindle further includes a ring fixing pin. The ring fixing pin moves in the radial direction in contact with the tip of the ring fixing screw. The ring fixing pin engages with the rotating portion, and the balance correcting ring is fixed to the rotating portion.

  According to this hydrostatic gas bearing spindle, the balance correcting ring can be moved in the radial direction by adjusting the tightening amounts of the plurality of ring fixing screws. By moving the balance correcting ring in the radial direction, it is possible to correct a large imbalance of the hydrostatic gas bearing spindle that cannot be corrected by adding a balance correcting weight or removing the unbalanced portion.

  Embodiments of the present invention will be described below with reference to the drawings. In the following drawings, the same or corresponding parts are denoted by the same reference numerals, and description thereof will not be repeated.

(Embodiment 1)
FIG. 1 is a schematic cross-sectional view showing a configuration of a static pressure gas bearing spindle according to Embodiment 1 of the present invention. As shown in FIG. 1, the static pressure gas bearing spindle 1 includes a rotating unit 2 that rotates about an axis O. The rotating portion 2 includes a cylindrical shaft portion 3, a disk-shaped thrust plate 4 that is joined to one end of the shaft portion 3 and has a diameter larger than that of the shaft portion 3, and a small diameter that is smaller than that of the shaft portion 3. A shaft portion 5. The small diameter shaft portion 5 is formed by the thrust plate 4 so as to be separated from the shaft portion 3 in the axis O direction. A thrust plate 4 is interposed between the shaft portion 3 and the small diameter shaft portion 5 in the direction of the axis O. The rotating part 2 includes a table 6 that is bolted to the other end of the shaft part 3 and fixes an object such as a workpiece, an inspection object, or a tool to the table surface 7 side.

  The hydrostatic gas bearing spindle 1 includes a fixed portion 10 that rotatably supports the rotating portion 2. The fixed portion 10 is provided on the outer periphery of the thrust plate 4, the housing 11 a forming the outermost peripheral portion of the static pressure gas bearing spindle 1, the hollow cylindrical bearing sleeves 12, 13 installed in the housings 11 a, 11 b. Spacer 14. The bearing sleeves 12 and 13 are provided so as to surround the outer peripheral surface of the cylindrical shaft portion 3, and the housings 11 a and 11 b are provided so as to surround the outer peripheral side surfaces of the hollow cylindrical bearing sleeves 12 and 13. The bearing sleeves 12 and 13 can be fixed to the housings 11a and 11b by shrink fitting, for example.

  The inner peripheral side surfaces of the bearing sleeves 12 and 13 and the outer peripheral side surface of the cylindrical shaft portion 3 facing the inner peripheral side surface include a cylindrical journal bearing surface parallel to the axis O. The journal bearing surface of the bearing sleeves 12 and 13, the journal bearing surface of the shaft portion 3, and the journal bearing gap between the shaft portion 3 and the bearing sleeves 12 and 13 support the rotating portion 2 at least in the radial direction. A static pressure gas journal bearing 21 is configured.

  The thrust plate 4 includes an annular thrust bearing surface perpendicular to the axis O on the surface in the axial direction facing the bearing sleeves 12 and 13. Further, the bearing sleeves 12 and 13 include a thrust bearing surface at an end surface facing the thrust plate 4. The thrust bearing surface of the bearing sleeves 12 and 13, the thrust bearing surface of the thrust plate 4, and the thrust bearing gap between the bearing sleeves 12 and 13 and the thrust plate 4 support the rotating unit 2 at least in the axial direction. A pair of static pressure gas thrust bearings 22a and 22b is configured.

  A supporting gas such as compressed air is supplied from a supporting gas supply source such as an air compressor (not shown) to an air supply path 23 formed inside the housing 11a and the bearing sleeves 12 and 13. The supporting gas is supplied from the supply passage 23 to the journal bearing gap via the journal bearing supply throttle, and is also supplied to the thrust bearing gap via the thrust bearing supply throttle. The supporting gas flowing out from the journal bearing gap and the thrust bearing gap is discharged to the outside of the hydrostatic gas bearing spindle 1 through the exhaust passage 24 formed in the housing 11a and the bearing sleeves 12 and 13.

  The fixed portion 10 rotatably supports the rotating portion 2 in a non-contact state by the pressure of the support gas supplied to the journal bearing gap and the thrust bearing gap. That is, the static pressure gas journal bearing 21 and the static pressure gas thrust bearings 22a and 22b are included in the static pressure gas bearing, and the fixed portion 10 is a rotating portion with respect to the fixed portion 10 via the static pressure gas bearing. 2 is rotatably supported in a non-contact manner.

  A motor unit including a motor rotor 17 and a motor stator 18 is installed inside the motor cover 15. Inside the motor cover 15, a motor rotor 17 is installed at the end of the small-diameter shaft portion 5 of the rotating unit 2, and a motor stator 18 is installed on the outer peripheral surface of the motor rotor 17. The rotating unit 2 is rotationally driven by supplying electric power to the motor stator 18. In order to control the rotation of the rotating unit 2, a rotary encoder 19 that detects a rotation angle is provided. The driving of the rotating unit 2 is not limited to this. For example, a turbine blade is attached to the rotating unit 2, and a fluid is ejected from a nozzle provided around the turbine blade to the turbine blade to drive the rotating unit 2 to rotate. Also good.

  In FIG. 1, the direction from the shaft 3 to the table 6 along the axis O that is the rotation center of the rotating unit 2 is the DR1 direction, and the direction from the shaft 3 to the rotary encoder 19 that is opposite to the DR1 direction is the DR2 direction. And In addition, the direction orthogonal to the DR1 direction and the DR2 direction, that is, the radial direction of the rotating unit 2 is the DR3 direction. The hydrostatic gas bearing spindle 1 shown in FIG. 1 further includes a balance correcting ring 31 provided on the outer peripheral side of the small diameter shaft portion 5. The balance correcting ring 31 is fixed to the small diameter shaft portion 5 with a plurality of ring fixing screws 32 interposed therebetween, and performs a rotational motion around the axis O together with the rotating portion 2. The ring fixing screw 32 is screwed into a screw hole 33 formed along the DR3 direction from the outer peripheral surface of the balance correcting ring 31 to fix the balance correcting ring 31 to the rotating portion 2.

  The balance correcting ring 31 is a member for correcting an unbalance on the rotary encoder 19 side of the static pressure gas bearing spindle 1. The balance correcting ring 31 is formed in a hollow, substantially cylindrical shape, and the cross-sectional shape of the balance correcting ring 31 perpendicular to the axis O is an annular shape. The balance correction ring 31 is formed with a balance correction tap 34a for adding a weight for balance correction. By adding a weight to the balance correction tap 34a, an imbalance of weight is added to the balance correction ring 31 in the circumferential direction of the annular cross-sectional shape. The balance correction tap 34 a is an attachment portion provided on the balance correction ring 31 and capable of attaching a weight for adding a weight unbalance to the balance correction ring 31.

  The screw hole 33 and the balance correcting tap 34a are at substantially the same position in the direction of the axis O. Typically, the center line of the screw hole 33 and the center line of the balance correcting tap 34a are on the same plane, which is a radial cross section of the hydrostatic gas bearing spindle 1. A tool insertion port 41 is formed in the housing 11b. Since the screw hole 33 and the balance correction tap 34a are in the above-described positional relationship, it is possible to insert a tool for adjusting the tightening amount of the ring fixing screw 32 via the tool insertion port 41 at one location. In addition, a weight for balance correction can be inserted through one tool insertion port 41. The tool insertion port 41 is formed as a tapped hole, and can be partitioned from the inside and the outside of the housing 11b by filling with a plug such as a bolt after balance correction.

  Further, the table 6 is formed with a balance correction tap 34b for adding a balance correction weight. The imbalance on the table 6 side of the static pressure gas bearing spindle 1 can be corrected by the balance correcting tap 34b.

  FIG. 2 is an enlarged schematic cross-sectional view showing the vicinity of the region II shown in FIG. As shown in FIG. 2 in an enlarged manner, the cross-sectional shape of the tip of the ring fixing screw 32 that fixes the balance correcting ring 31 to the rotating portion 2 is a tapered shape that is inclined with respect to the axial direction and the radial direction. A groove portion 35, which is a V groove inclined at the same angle as the tip shape of the ring fixing screw 32, is processed on the outer peripheral surface of the small diameter shaft portion 5 with which the tapered portion comes into contact. The groove portion 35 is formed in a V-groove shape in which the shape of the cross section perpendicular to the extending direction of the groove portion 35 (that is, the circumferential direction of the small-diameter shaft portion 5) is V-shaped.

  In a state where the balance correcting ring 31 is fixed to the small-diameter shaft portion 5 of the rotating portion 2 by the ring fixing screw 32, the tip end portion of the ring fixing screw 32 is in contact with the inner surface 36 of the groove portion 35. The inner surface 36 of the groove portion 35 and the contact surface 37 of the ring fixing screw 32 that contacts the inner surface 36 of the groove portion 35 are inclined with respect to the axial direction (ie, DR1 direction, DR2 direction) and the radial direction (ie, DR3 direction). ing. The inner surface 36 and the contact surface 37 are formed non-parallel to the axial direction and the radial direction.

  The groove portion 35 which is a V groove is processed at a position slightly shifted in the axial direction from the straight line in which the ring fixing screw 32 extends. The ring fixing screw 32 is screwed into a screw hole 33 formed in the balance correcting ring 31. The screw hole 33 is formed to extend in the radial direction from the outer peripheral side of the balance correcting ring 31, and is open to the outer peripheral side of the balance correcting ring 31. In a state where the balance correcting ring 31 is fixed to the small diameter shaft portion 5, the center line CL of the screw hole 33 is shifted in the axial direction with respect to the deepest portion 38 of the groove portion 35. There is a mismatch in the axial direction. The contact surface 37 of the ring fixing screw 32 has a conical shape. Therefore, the protruding end 39 of the ring fixing screw 32 is the apex of the cone formed by the contacting surface 37, and the protruding end 39 is on the center line of the cone. It is in. The protruding end 39 is disposed on the center line CL of the screw hole 33. The screw hole 33 into which the ring fixing screw 32 is screwed is formed so that the protruding end 39 is disposed at a position slightly away from the deepest portion 38 of the groove portion 35 in the axial direction.

  The surface 4a on the direction DR2 side of the thrust plate 4 shown in FIG. 1 faces the end surface 31a on the direction DR1 side of the balance correcting ring 31. The surface 4 a of the thrust plate 4 is a thrust surface (axial surface) extending in the radial direction perpendicular to the axis O, and includes a thrust bearing surface that forms a static pressure gas thrust bearing 22 b together with the bearing sleeve 13. The rotating part 2 includes a thrust plate 4, and the thrust plate 4 is a surface 4 a as a thrust surface which is a surface facing the end surface 31 a of the balance correction ring 31 in the direction of the axis O and extending in the radial direction. Have

  The inner surface 36 of the groove 35 and the contact surface 37 of the ring fixing screw 32 are inclined with respect to the axial direction and the radial direction so as to approach the axial line O in the radial direction as approaching the surface 4a in the axial direction. . That is, when a point on the inner surface 36 (abutment surface 37) moves in the DR1 direction, which is the axial direction on the side approaching the surface 4a, this point is oriented in the direction closer to the axis O in the radial direction. It will be moving. The center line CL of the screw hole 33 is shifted in the axial direction on the side away from the surface 4 a of the thrust plate 4 with respect to the deepest portion 38 of the groove portion 35.

  Since the balance correcting ring 31 and the groove 35 are formed in this way, when the ring fixing screw 32 is tightened, the balance correcting ring 31 is moved in a direction to bring the end surface 31a closer to the surface 4a of the thrust plate 4. Move in the direction of the axis O. When the ring fixing screw 32 is screwed into the screw hole 33, the end surface 31 a of the balance correcting ring 31 is pressed against the surface 4 a of the thrust plate 4 of the rotating unit 2. The abutment surface 37 of the ring fixing screw 32 is in close contact with the inner surface 36 of the groove portion 35 to fix the radial position of the balance correcting ring 31. Further, the end surface 31a of the balance correcting ring 31 abuts on the surface 4a of the thrust plate 4, and the position of the balance correcting ring 31 in the axial direction is fixed.

  That is, by tightening the ring fixing screw 32, the axial direction and the radial direction of the balance correcting ring 31 can be simultaneously fixed. Accordingly, the fixing of the balance correcting ring 31 is stable and resistant to disturbance. As a result, it is possible to suppress deterioration of the rotational accuracy of the static pressure gas bearing spindle 1 during high-speed rotation.

  Hereinafter, the balance correction method will be described. First, a commercially available balance measuring device may be used to check which phase of the rotating unit 2 is rotating and how much unbalance there is. After confirming the phase and amount of unbalance, the balance can be corrected by adding a weight corresponding to the unbalance to the balance correction taps 34a and 34b. Further, the balance can be corrected by cutting any position of the balance correcting ring 31.

  Furthermore, when the unbalance of the rotating part 2 is large and the balance correction is insufficient even if the weight is added or the unbalanced part is removed, the fixing position in the radial direction of the balance correcting ring 31 can be adjusted. be able to. At least three ring fixing screws 32 are installed on the circumference in the circumferential direction of the balance correcting ring 31. By adjusting the tightening amount by tightening each ring fixing screw 32, the balance correcting ring 31 can be adjusted. The fixed position in the radial direction can be changed.

  An appropriate gap is formed between the inner peripheral side of the balance correcting ring 31 and the outer peripheral portion of the small-diameter shaft portion 5 facing it. Further, an appropriate gap is formed between the outer peripheral side of the balance correcting ring 31 and the inner peripheral side of the bearing sleeve 13 opposed thereto. By adjusting each of the plurality of ring fixing screws 32, it is possible to move the balance correcting ring 31 in the range of the gap, using an arbitrary angle and an arbitrary distance in the radial direction as an adjustment range.

  At this time, the gap between the outer peripheral side of the balance correcting ring 31 and the inner peripheral side of the bearing sleeve 13 is larger than the gap between the inner peripheral side of the balance correcting ring 31 and the outer peripheral portion of the small diameter shaft portion 5. , Can be formed larger. By forming the gap in this way, even when the balance correcting ring 31 is moved to the limit of the adjustment range, the contact between the outer diameter of the balance correcting ring 31 and the inner diameter of the bearing sleeve 13 is suppressed. Can do.

  As described above, the static pressure gas bearing spindle 1 according to the first embodiment includes the rotating portion 2 that rotates about the axis O, the rotating portion via the static pressure gas journal bearing 21 and the static pressure gas thrust bearings 22a and 22b. 2 is rotatably provided, and a balance correcting ring 31 fixed to the rotating unit 2 is provided. The balance correcting ring 31 is fixed to the rotating unit 2 using a plurality of ring fixing screws 32, and performs a rotational motion around the axis O together with the rotating unit 2. The balance correcting ring 31 is provided so that the radial fixing position can be changed by adjusting the tightening amount of the ring fixing screw 32.

  In this way, the balance correction ring 31 can be moved in the radial direction by adjusting the tightening amounts of the plurality of ring fixing screws 32. By moving the balance correcting ring 31 in the radial direction after the assembly of the hydrostatic gas bearing spindle 1 is completed, it is possible to easily correct a large unbalance that cannot be corrected by adding a balance correcting weight or removing the unbalanced portion. it can. Further, the balance can be corrected by moving the balance correcting ring 31 in the radial direction, and the amount of scraping off a part of the balance correcting ring 31 for correcting the balance can be reduced, so that scattering of shavings can be reduced. Is possible.

(Embodiment 2)
In the first embodiment, the balance correction ring 31 is arranged on the rotary encoder 19 side with respect to the static pressure gas bearing (that is, the static pressure gas journal bearing 21 and the static pressure gas thrust bearings 22a and 22b) for supporting the rotating unit 2. The case where it was installed in was explained. The balance correcting ring can also be attached to the table 6 side with respect to the static pressure gas bearing. That is, the rotating unit 2 has an end on the table 6 side (DR1 direction) as one end that is one end in the direction of the axis O, and a rotary encoder 19 side (the other end that is the end opposite to the one end). The balance correcting ring can be attached to either or both of the table 6 side and the rotary encoder 19 side of the static pressure gas bearing.

  FIG. 3 is a partial cross-sectional schematic diagram showing a configuration in the vicinity of the table of the static pressure gas bearing spindle of the second embodiment. As shown in FIG. 3, a balance correcting ring 51 may be installed on the outer diameter side of the table 6. For fixing the balance correcting ring 51, a ring fixing screw 52 screwed into the screw hole 53 is used. The screw hole 53 is formed in the radial direction so as to open to the outer peripheral side of the balance correcting ring 51.

  Similarly to the first embodiment, the center line of the screw hole 53 is on the side away from the flange portion 6 a formed on the shaft portion 3 side of the table 6 with respect to the deepest portion of the groove portion formed on the outer peripheral surface of the table 6. Furthermore, it is shifted in the direction of the axis O. The DR1 direction surface of the flange portion 6a faces the DR2 direction surface of the balance correcting ring 51. The inner surface of the groove formed on the outer peripheral surface of the table 6 and the contact surface of the ring fixing screw 52 that contacts the inner surface approach the axis O in the radial direction as they approach the flange portion 6a in the axis O direction. Thus, it inclines with respect to an axial direction and a radial direction, and is formed non-parallel. With such a configuration, when the ring fixing screw 52 is screwed into the screw hole 53, the balance correction ring 51 moves in the direction of the axis O so as to approach the flange portion 6a. Direction fixation and axial direction fixation can be performed simultaneously.

  The balance of the hydrostatic gas bearing spindle can be corrected by attaching a weight to the balance correcting tap 54 as the mounting portion or by cutting any part of the balance correcting ring 51. Further, by adjusting each of the plurality of ring fixing screws 52, the balance correcting ring 51 is moved at an arbitrary distance and at an arbitrary angle by an amount corresponding to a gap formed between the balance correcting ring 51 and the table 6. This makes it possible to easily correct a large imbalance.

(Embodiment 3)
FIG. 4 is a partial cross-sectional schematic diagram showing the configuration in the vicinity of the table of the static pressure gas bearing spindle of the third embodiment. The configuration of the third embodiment is different from that of the second embodiment in the installation location of the balance correction ring. Specifically, in the second embodiment, the balance correcting ring 51 is installed outside the table 6, whereas in the third embodiment, the balance correcting ring 61 is provided inside the shaft portion 3 as shown in FIG. Is installed.

  In the balance correcting ring 61, a screw hole 63 into which the ring fixing screw 62 is screwed is formed in the axis O direction. A ring fixing pin 68 is provided inside the balance correcting ring 61 and moves radially outward by contacting the tip of the ring fixing screw 62. When the ring fixing pin 68 is engaged with the shaft portion 3, the balance correcting ring 61 can be fixed to the shaft portion 3. Further, a balance correction tap 64 is formed on the table 6 so that a weight can be attached.

  The ring fixing pin 68 is pressed against the shaft portion 3 in the direction from the inner side to the outer side in the radial direction, and is fixed to the shaft portion 3. The inner surface of the groove portion that engages with the tip portion of the ring fixing pin 68 formed in the shaft portion 3 and the contact surface of the ring fixing pin 68 that contacts the inner surface are radial in the direction toward the DR2 direction in the axis O direction. Are inclined with respect to the axial direction and the radial direction so as to be away from the axis O, and are formed non-parallel. That is, in the third embodiment, the tapers are butted together via the ring fixing pin 68.

  As in the first and second embodiments, when the ring fixing screw 62 is screwed into the screw hole 63, the ring fixing pin 68 is pressed radially outward and pressed against the shaft portion 3, whereby the balance correcting ring 61 is pressed. The position in the radial direction is fixed. At the same time, the balance correcting ring 61 moves so as to be pressed against the shaft portion 3 in the axial direction, and the position in the axial direction is fixed. Therefore, the radial fixing and the axial fixing of the balance correcting ring 61 can be performed at the same time.

  The balance of the hydrostatic gas bearing spindle can be corrected by attaching a weight to the balance correcting tap 64 as the mounting portion or by cutting any part of the balance correcting ring 61. Further, by adjusting each of the plurality of ring fixing screws 62, the balance correcting ring can be set at an arbitrary angle at an arbitrary angle by a gap formed in the radial direction between the balance correcting ring 61 and the shaft portion 3. Since 61 can be moved, a large imbalance can be easily corrected.

  Further, since the balance correcting ring 61 is installed inside the shaft portion 3, it is caused by the friction between the rotating portion and the air that occurs when the static pressure gas bearing spindle is rotated, particularly when it is rotated at a high speed. Disturbance can be suppressed.

(Embodiment 4)
FIG. 5 is a partial cross-sectional schematic diagram showing a configuration in the vicinity of the table of the static pressure gas bearing spindle of the fourth embodiment. The configuration of the fourth embodiment is different from that of the second embodiment in the installation location of the balance correction ring. Specifically, in the second embodiment, the balance correcting ring 51 is installed outside the table 6, whereas in the fourth embodiment, the balance correcting ring 71 is provided inside the table 6 as shown in FIG. It is installed.

  A screw hole 73 into which the ring fixing screw 72 is screwed is formed in the table 6 in the radial direction from the outer peripheral side of the table 6. A plurality of ring fixing screws 72 screwed into the screw holes 73 are used to fix the balance correcting ring 71. A balance correcting tap 74a is formed on the balance correcting ring 71, and a balance correcting tap 74b is formed on the table 6, so that a weight can be attached.

  The inner surface of the groove portion formed on the outer peripheral surface of the balance correcting ring 71 and the contact surface of the ring fixing screw 72 that contacts the inner surface are axially O in the radial direction as approaching the shaft portion 3 in the axis O direction. It is inclined with respect to the axial direction and the radial direction so as to be away from the center, and is formed non-parallel. Similarly to the first embodiment, when the ring fixing screw 72 is screwed into the screw hole 73, the ring fixing screw 72 is pressed against the inner surface of the groove portion formed on the outer peripheral side of the balance correcting ring 71 to fix the position. At the same time, the balance correcting ring 71 moves so as to be pressed against the shaft portion 3 in the axial direction. Therefore, the radial fixing and the axial fixing of the balance correcting ring 71 can be performed at the same time.

  The balance of the hydrostatic gas bearing spindle can be corrected by attaching weights to the balance correcting taps 74a and 74b as the mounting portions or by cutting any part of the balance correcting ring 71. Further, by adjusting each of the plurality of ring fixing screws 72, the balance correcting ring 71 is moved at an arbitrary angle at an arbitrary distance by a gap formed between the balance correcting ring 71 and the table 6. This makes it possible to easily correct a large imbalance.

  Further, since the balance correcting ring 71 is installed inside the table 6, disturbance caused by friction between the rotating portion and air, which occurs when the static pressure gas bearing spindle is rotated, particularly when rotated at a high speed. Can be suppressed.

  Although the embodiments of the present invention have been described above, the configurations of the embodiments may be appropriately combined. In addition, it should be considered that the embodiment disclosed this time is illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

FIG. 3 is a schematic cross-sectional view showing the configuration of the static pressure gas bearing spindle of the first embodiment. It is a cross-sectional schematic diagram which expands and shows the area | region II vicinity shown in FIG. FIG. 6 is a partial cross-sectional schematic diagram showing a configuration in the vicinity of a table of a static pressure gas bearing spindle of a second embodiment. FIG. 6 is a partial cross-sectional schematic diagram showing a configuration in the vicinity of a table of a static pressure gas bearing spindle of a third embodiment. FIG. 6 is a partial cross-sectional schematic diagram showing a configuration in the vicinity of a table of a static pressure gas bearing spindle of a fourth embodiment. It is a cross-sectional schematic diagram which shows the structure of the static pressure gas bearing spindle provided with the conventional balance correction means.

Explanation of symbols

  1 static pressure gas bearing spindle, 2 rotating part, 3 shaft part, 4 thrust plate, 4a surface, 5 small diameter shaft part, 6 table, 6a flange part, 7 table surface, 10 fixed part, 11a, 11b housing, 12, 13 Bearing sleeve, 14 spacer, 15 motor cover, 17 motor rotor, 18 motor stator, 19 rotary encoder, 21 static pressure gas journal bearing, 22a, 22b static pressure gas thrust bearing, 23 air supply path, 24 exhaust path, 31, 51, 61, 71 Balance correction ring, 31a end face, 32, 52, 62, 72 Ring fixing screw, 33, 53, 63, 73 Screw hole, 34a, 34b, 54, 64, 74a, 74b Balance correction tap, 35 Groove , 36 inner surface, 37 abutting surface, 38 deepest part, 39 protruding end, 41 tool insertion port , 68 Ring fixing pin, CL center line, O axis line.

Claims (7)

A rotating part that rotates around an axis;
A fixed portion that rotatably supports the rotating portion via a static pressure gas bearing;
A balance correcting ring that is fixed to the rotating part and performs rotational movement around an axis together with the rotating part;
The balance correcting ring is fixed to the rotating portion using a plurality of ring fixing screws, and is provided so that a radial fixing position can be changed by adjusting a tightening amount of the ring fixing screws. Hydrostatic gas bearing spindle.   The static pressure gas bearing spindle according to claim 1, wherein the balance correcting ring is provided with an attachment portion to which a weight can be attached. The rotating part has one end which is one end in the axial direction and the other end which is an end opposite to the one end.
3. The static pressure gas according to claim 1, wherein the balance correcting ring is fixed to the rotating part at least one of one end side and the other end side of the static pressure gas bearing. Bearing spindle. A groove is formed in the rotating part,
In a state where the balance correcting ring is fixed to the rotating portion, the tip end portion of the ring fixing screw is in contact with the inner surface of the groove portion,
The inner surface of the groove and the contact surface of the ring fixing screw that contacts the inner surface are formed non-parallel to the axial direction and the radial direction. Of static pressure gas bearing spindle. The balance correcting ring is formed with a screw hole in a radial direction in which the ring fixing screw is screwed.
5. The hydrostatic gas bearing spindle according to claim 4, wherein a center line of the screw hole is shifted in an axial direction with respect to a deepest portion of the groove portion in a state where the balance correcting ring is fixed to the rotating portion. The screw hole is formed so as to open to the outer peripheral side of the balance correcting ring,
The rotating portion includes a thrust surface that is a surface facing an end surface of the balance correcting ring,
The inner surface and the contact surface are inclined with respect to the axial direction and the radial direction so as to approach the axial line in the radial direction as approaching the thrust surface in the axial direction,
The center line of the screw hole is shifted to the side away from the thrust surface in the axial direction with respect to the deepest part of the groove,
6. The hydrostatic gas bearing spindle according to claim 5, wherein when the ring fixing screw is screwed into the screw hole, the balance correcting ring moves in an axial direction in a direction in which the end surface approaches the thrust surface. In the balance correction ring, a screw hole into which the ring fixing screw is screwed is formed in the axial direction,
The static pressure gas bearing spindle further includes a ring fixing pin that moves in a radial direction in contact with the tip of the ring fixing screw;
The static pressure gas bearing spindle according to any one of claims 1 to 3, wherein the ring fixing pin engages with the rotating portion to fix the balance correcting ring to the rotating portion.

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