JP2007247762A - Static pressure gas bearing spindle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a static pressure gas bearing spindle with a rotating part having a reduced axial length without lowering both the rotating accuracy of the rotating part and the performance of an object fixing means. <P>SOLUTION: In the static pressure gas bearing spindle 1, gas is distributed between a ventilation hole 29 and the object fixing means via a rotation side ventilation passage 32 provided in a thrust plate 4 and a fixation side ventilation passage 30 provided in the fixing part to change gas pressure in the object fixing means. The rotation side ventilation passage 32 which has one end connected to the motor side surface of the thrust plate 4 is provided in the thrust plate 4, so as not to require for providing a conventional ventilating sleeve. Thus, the rotating part 2 has a reduced axial length, compared with that of a conventional static pressure gas bearing spindle, without reducing the axial length of a static pressure gas journal bearing. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

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

  A hydrostatic gas bearing in which a rotating part is supported with respect to a fixed part by supplying a gas such as compressed air between the rotating part and a member facing the rotating part in the fixed part. In the provided hydrostatic gas bearing spindle, the rotating part is supported in a non-contact state with respect to the fixed part. Therefore, the friction loss in the bearing is small, and the heat generated when the rotating part rotates at high speed is also small. In addition, since the rotating part and the member facing the rotating part are not in direct contact with each other, a highly accurate and smooth rotational movement is possible, and material fatigue and wear do not occur as long as the operating state is normal. Taking advantage of such characteristics, the hydrostatic gas bearing spindle is widely used as a high-precision spindle or a high-speed spindle.

  In a static pressure gas bearing spindle used for a precision machining apparatus, a precision inspection apparatus, or the like, an object fixing means for fixing an object such as a workpiece, an inspection object, or a tool to a rotating part may be provided. The object fixing means includes, for example, an air passage having an opening at the end of the rotating portion, and by passing a gas through the air passage and changing the gas pressure, the object such as a workpiece is turned into the rotating portion. Fix it.

  FIG. 6 is a schematic cross-sectional view showing a configuration of a static pressure gas bearing spindle provided with an object fixing means. In FIG. 6, the static pressure gas bearing spindle 101 includes a rotating unit 102. The rotating portion 102 includes a cylindrical shaft portion 103, a disk-shaped thrust plate 104 that is bonded to the end surface of the shaft portion 103 and has a diameter larger than that of the shaft portion 103, and an axis parallel to the center line of the cylindrical shaft portion 103. And another thrust plate 105 formed at a distance from the thrust plate 104 in the direction and disposed opposite to the thrust plate 104. In the rotating part 102, the outer peripheral surface of the shaft part 103 is surrounded by a bearing sleeve 106, a bearing sleeve 107, and a ventilation sleeve 108. The cross-sectional shapes of the bearing sleeve 106, the bearing sleeve 107, and the ventilation sleeve 108 in a cross section perpendicular to the axial direction are annular. The ventilation sleeve 108 is disposed between the bearing sleeve 106 and the bearing sleeve 107. Further, the bearing sleeve 106, the bearing sleeve 107, the ventilation sleeve 108 and the other thrust plate 105 are surrounded by a housing 109. The bearing sleeve 106, the bearing sleeve 107, the ventilation sleeve 108, and the housing 109 constitute a fixed portion.

  A hydrostatic gas journal bearing 110 is provided on the inner diameter side of the ring-shaped bearing sleeve 106 and the bearing sleeve 107 so as to face the outer peripheral surface of the columnar shaft portion 103, and through a fine journal bearing gap. The rotating unit 102 is pivotally supported in the radial direction. The end face of the bearing sleeve 106 and the end face of the bearing sleeve 107 are respectively provided with a static pressure gas thrust bearing 111 so as to face the thrust plate 104 and the other thrust plate 105, and the rotating part is interposed through a fine thrust bearing gap. 102 is supported in the axial direction. A support gas such as compressed air is supplied from a support gas supply source such as an air compressor (not shown) to a support gas supply port 112 provided on the outer wall of the housing 109. The support gas is supplied to the journal bearing gap via a support gas supply path 113 and a journal bearing supply throttle 114 connected to the support gas supply port 112. Further, the support gas is supplied through the support gas supply passage 113 and the thrust bearing supply throttle 115 to the thrust bearing gap. Thereby, in the gap between the rotating part 102 and the fixed part, the rotating part 102 is rotatably supported in a non-contact state with respect to the fixed part by the pressure of the supplied support gas.

  The gas flowing out from the journal bearing gap and the thrust bearing gap is discharged to the outside of the static pressure gas bearing spindle 101 through the exhaust passage 116 and the exhaust passage 117.

  The housing 109 includes a vent hole 118 provided in the outer wall. The ventilation hole 118 is connected to the thrust plate 104 via a fixed-side ventilation channel 119 formed in the ventilation sleeve 108 and the housing 109 and a rotation-side ventilation channel 120 formed in the shaft portion 103 and the thrust plate 104. It communicates with an opening 121 formed on the end face.

  Conventionally, a static pressure gas bearing spindle having a vacuum chuck mechanism has been disclosed using the static pressure gas bearing spindle having the above-described configuration (see, for example, Patent Document 1). In the static pressure gas bearing spindle 101, when the vent 118 is connected to a negative pressure source such as a vacuum pump (not shown) provided outside and the negative pressure source is operated, the vent 118, the fixed side vent 119, and the rotation side vent The opening 121 is depressurized via the path 120. At this time, the object is attracted and fixed to the surface of the thrust plate 104 by bringing the object into contact with the opening 121. In this way, the vacuum chuck mechanism of the static pressure gas bearing spindle 101 functions.

Further, a centering and holding device using a fluid pressure using a static pressure gas bearing spindle having the above-described configuration has been conventionally disclosed (for example, see Patent Document 2). In the static pressure gas bearing spindle 101 having the above-described configuration, when the vent 118 is connected to a positive pressure source such as a compressor (not shown) provided outside and the positive pressure source is operated, the vent 118 and the fixed-side vent 119 are provided. And the opening 121 is pressurized through the rotation-side air passage 120. At this time, by connecting a centering holding device to the opening 121, the piston is moved by pressurization, and a plurality of clamp pins are pushed out in a radial direction via a tapered portion provided on the piston, so that the clamp pins are perforated discs. The disk is centered and held in contact with the inner surface of the disk. In this way, the centering and holding device of the static pressure gas bearing spindle 101 functions.
JP 7-217655 A Japanese Patent Laid-Open No. 11-16236

  When the static pressure gas bearing spindle is installed in a state where the rotating part is leveled, it is necessary to shorten the axial length of the rotating part in order to reduce the size of the apparatus.

  In a structure in which a ventilation sleeve is arranged between a plurality of bearing sleeves as in a conventional static pressure gas bearing spindle, when the axial length of the rotating portion is shortened, the axial length of the bearing sleeve is shortened. As a result, the axial length of the hydrostatic gas journal bearing is reduced and the rigidity is lowered. For this reason, the rotation accuracy of the rotating part is lowered. Alternatively, the axial length of the ventilation sleeve is shortened, so that the axial length of the seal gap between the inner diameter side surface of the ventilation sleeve and the outer peripheral surface of the shaft portion opposed thereto is reduced. For this reason, the flow rate of fluid leakage from the seal gap increases, and sufficient negative pressure or positive pressure cannot be obtained in the object fixing means, making it difficult to hold the object in an accurate position.

  Therefore, a main object of the present invention is to provide a hydrostatic gas bearing spindle capable of shortening the axial length of the rotating part without reducing both the rotational accuracy of the rotating part and the performance of the object fixing means. That is.

  A hydrostatic gas bearing spindle according to the present invention is a hydrostatic gas bearing spindle including an object fixing means that operates by gas pressure, and includes a rotating part and a fixing part. The rotating part includes a cylindrical journal bearing surface parallel to the rotation center axis and an annular thrust bearing surface perpendicular to the rotation center axis. The fixed part supports the rotating part. The fixed portion has a hydrostatic gas journal bearing that faces the journal bearing surface of the rotating portion in the radial direction and supports the rotating portion at least in the radial direction. Further, the fixed portion has a static pressure gas thrust bearing that faces the thrust bearing surface of the rotating portion in the axial direction and supports the rotating portion at least in the axial direction. In addition, at least one of the plane including the thrust bearing surface in the rotating portion and the plane including the surface facing the thrust bearing surface in the fixed portion has an annular shape concentrically with the rotation center axis. Provide a ventilation groove. The fixing part has a vent provided in the outer wall of the fixing part, and a fixed-side air passage that communicates the vent and the ventilation groove. The rotating part has a rotation-side air passage that communicates the air groove and the object fixing means. And the gas for changing a gas pressure in a target object fixing means is distribute | circulated between a target and an object fixing means through a fixed side ventilation path and a rotation side ventilation path.

  In this case, at least one of the plane including the thrust bearing surface in the rotating portion and the plane including the surface opposed to the thrust bearing surface in the fixed portion has an annular shape concentrically with the rotation center axis. A vent groove with a shape is provided. Then, the vent and the object fixing means are communicated with each other through the fixed side air passage, the air groove, and the rotation side air passage. Therefore, it is not necessary to provide a conventional ventilation sleeve in order to circulate the gas for changing the gas pressure in the object fixing means. Therefore, without reducing the axial length of the bearing sleeve, i.e., the axial length of the hydrostatic gas journal bearing, the axial length of the ventilation sleeve relative to the conventional hydrostatic gas bearing spindle, The axial length of the rotating part can be shortened.

  In addition, since the fixed-side air passage and the rotation-side air passage communicate with each other via an annular vent groove provided concentrically with the rotation center axis, the fixed-side air passage and the rotation-side air passage are also rotated during rotation of the rotating portion. There is always communication with the road. Therefore, the object fixing means can always function stably while the rotating portion is rotating. Further, even if the end of the fixed-side air passage and the end of the rotating-side air passage are not arranged at exactly opposite positions, the fixed-side air passage and the rotating-side air passage are within the width of the air groove. Can communicate with each other. Therefore, the influence of the processing accuracy of the fixed-side air passage and the rotation-side air passage on the performance of the object fixing means can be reduced.

  Preferably, the fixed portion includes a static pressure gas thrust bearing and another static pressure gas thrust bearing formed at a distance from the static pressure gas thrust bearing in the axial direction. The rotating portion is supported in the axial direction by forces opposite to each other generated in the hydrostatic gas thrust bearing and other hydrostatic gas thrust bearings. And on the plane including the other thrust bearing surface of the annular shape perpendicular to the rotation center axis facing the other static pressure gas thrust bearing in the rotating portion, and the surface facing the other thrust bearing surface in the fixed portion Another vent groove having an annular shape is provided on a concentric circle with the rotation center axis on at least one of the planes included. And it has a ventilation groove communicating path which connects a ventilation groove and another ventilation groove.

  In this case, it is possible to prevent the rotating part from being displaced in the axial direction when a positive pressure or a negative pressure is supplied to make the object fixing means function.

  That is, in the rotating part supported by a plurality of static pressure gas thrust bearings, the rotating part is supported in the axial direction by the balance of the bearing reaction force. In such a configuration of the hydrostatic gas bearing spindle, if the ventilation groove is provided only on the plane including the thrust bearing surface in the rotating portion or the plane including the surface facing the thrust bearing surface in the fixed portion, the vacuum chuck mechanism When the negative pressure for functioning or the positive pressure for functioning the centering holding device is supplied and the pressure in the ventilation groove changes, axial force acting on the rotating part is generated. There is a case where it is displaced in the direction and moved to a new balance position. Here, the bearing reaction force refers to a force generated in the axial direction as a reaction of a force by which a supporting gas such as compressed air supplied from the outside to the thrust bearing gap pushes the thrust bearing surface included in the rotating portion. .

  On the other hand, at least one of the plane including the thrust bearing surface in the rotating portion and the plane including the surface facing the thrust bearing surface in the fixed portion is concentric with the rotation center axis. An annular vent groove is provided. In addition, at least one of the plane including the other thrust bearing surface in the rotating portion and the plane including the surface facing the other thrust bearing surface in the fixed portion is concentric with the rotation center axis. Provide another annular groove in the shape of a ring. Here, the other thrust bearing surface is a plane on the surface of the rotating portion that is perpendicular to the central axis of rotation and faces the other static pressure gas thrust bearing of the fixed portion. And the ventilation groove communication path which connects a ventilation groove and another ventilation groove is provided. At this time, for example, the projected areas of the ventilation groove and other ventilation grooves on the plane including the thrust bearing surface can be made equal. As a result, when the vent is connected to the positive pressure source or the negative pressure source, equal pressure is simultaneously generated in the vent groove and the other vent grooves. Therefore, a force having the same magnitude and opposite direction acts on the rotating part, so that the rotating part can be prevented from being displaced in the axial direction.

  Preferably, the ventilation groove communication path is provided in the fixed portion, and one end portion is connected to the fixed-side air passage and the other end portion is connected to the other ventilation groove.

  In this case, the vent hole and the vent groove communicate with each other through the fixed-side vent path, and the vent hole and the other vent groove communicate with each other through the fixed-side vent path and the vent groove communicating path. Therefore, when the vent is connected to the positive pressure source or the negative pressure source, equal pressure is simultaneously generated in the vent groove and the other vent grooves. Therefore, a force having the same magnitude and opposite direction acts on the rotating part, so that the rotating part can be prevented from being displaced in the axial direction.

  Preferably, the ventilation groove communication path is provided in the rotating part. In this case, the vent hole and the vent groove are communicated with each other through the fixed-side vent path, and the vent groove and the other vent groove are communicated with each other through the vent groove communicating path. Therefore, when the vent is connected to the positive pressure source or the negative pressure source, equal pressure is simultaneously generated in the vent groove and the other vent grooves. Therefore, a force having the same magnitude and opposite direction acts on the rotating part, so that the rotating part can be prevented from being displaced in the axial direction.

  Preferably, the fixed portion includes a static pressure gas thrust bearing and another static pressure gas thrust bearing formed at a distance from the static pressure gas thrust bearing in the axial direction. The rotating portion is supported in the axial direction by forces opposite to each other generated in the static pressure gas thrust bearing and the other static pressure gas thrust bearing. Then, on the plane including the thrust bearing surface in the rotating portion, on the plane including the surface facing the thrust bearing surface in the fixed portion, and perpendicular to the rotation center axis facing the other hydrostatic gas thrust bearing in the rotating portion. A circle that is concentric with the center axis of rotation at least one of a plane that includes another thrust bearing surface that has an annular shape and a plane that includes a surface that faces the other thrust bearing surface in the fixed portion Another vent groove with a ring shape is provided. In addition, the fixed portion includes another vent provided in the outer wall of the fixed portion and another fixed-side air passage that communicates the other vent and the other vent groove. The rotating unit has another rotation-side ventilation path that communicates the other ventilation groove with the object fixing means. Then, a gas for changing the gas pressure is circulated in the object fixing means between the other vent and the object fixing means via the other fixed side air passage and the other rotation side air passage.

  In this case, the gas pressure supplied from the plurality of vents to the object fixing means via the plurality of fixed-side vent passages, the plurality of vent-grooves, and the plurality of rotation-side vent passages for each vent port. Any pressure can be set. That is, the gas pressure supplied from the vent and the gas pressure supplied from the other vent can be set to the same pressure setting, or can be set to different pressure settings. For example, the vent can be connected to a positive pressure source to cause the centering device to function, and the other vent can be connected to a negative pressure source to cause the vacuum chuck mechanism to function. At this time, the plurality of ventilation grooves include a surface that includes the thrust bearing surface or other thrust bearing surface in the rotating portion, and a surface that faces the thrust bearing surface or other surface that faces the thrust bearing surface in the fixed portion. It is provided either on the flat surface. Accordingly, the rotating portion is equivalent to the axial length of the two ventilation sleeves in comparison with the conventional static pressure gas bearing spindle that requires two ventilation sleeves to function the centering device and the vacuum chuck mechanism, respectively. The axial length can be shortened.

  As described above, in the static pressure gas bearing spindle according to the present invention, at least one of the plane including the thrust bearing surface in the rotating portion and the plane including the surface opposed to the thrust bearing surface in the fixed portion. On the other hand, an annular ventilation groove is provided concentrically with the rotation center axis. Then, the vent and the object fixing means are communicated with each other through the fixed side air passage, the air groove, and the rotation side air passage. Therefore, it is not necessary to provide a conventional ventilation sleeve in order to circulate the gas for changing the gas pressure in the object fixing means. Therefore, without reducing the axial length of the bearing sleeve, i.e., the axial length of the hydrostatic gas journal bearing, the axial length of the ventilation sleeve relative to the conventional hydrostatic gas bearing spindle, The axial length of the rotating part can be shortened.

  Hereinafter, embodiments of the present invention will be described 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, which is an embodiment of the present invention. The hydrostatic gas bearing spindle 1 includes an object fixing means (not shown) that operates by gas pressure. Here, the object fixing means refers to a vacuum chuck mechanism for adsorbing and fixing an object using negative pressure, a centering holding device for centering a perforated disk using positive pressure, and the like.

  In FIG. 1, the static pressure gas bearing spindle 1 includes a rotating portion 2, a fixed portion constituted by a bearing sleeve 6, a bearing sleeve 7, and a housing 8. The rotating portion 2 includes a cylindrical shaft portion 3, a disk-shaped thrust plate 4 joined to the end surface of the shaft portion 3 and having a diameter larger than that of the shaft portion 3, and an axis parallel to the center line of the cylindrical shaft portion 3. And another thrust plate 5 which is formed at a distance from the thrust plate 4 in the direction and is disposed opposite to the thrust plate 4. A cross-sectional shape of the bearing sleeve 6 and the bearing sleeve 7 in a cross section perpendicular to the axial direction is an annular shape. The bearing sleeve 6 and the bearing sleeve 7 are provided so as to surround the outer peripheral surface of the cylindrical shaft portion 3, and the housing 8 is provided so as to surround the outer peripheral surface of the annular bearing sleeve 6 and the bearing sleeve 7. Yes. The bearing sleeve 6 and the bearing sleeve 7 can be fixed to the housing 8 by, for example, shrink fitting.

  A motor rotor 9 is installed on the rotating portion 2, and a motor stator 10 is installed on the motor housing 11 so as to surround the outer peripheral surface of the motor rotor 9. The rotating unit 2 is driven to rotate by supplying electric power to the motor stator 10. In order to control the rotation, a rotary encoder 12 that detects a rotation angle may be provided. A direction from the shaft portion 3 toward the motor rotor 9 is a motor side direction 14, and a direction opposite to the motor side direction 14 is a workpiece side direction 13.

  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.

  The outer peripheral surface of the cylindrical shaft portion 3 includes a cylindrical journal bearing surface 15 having a cylindrical shape parallel to the rotation center axis. The surface of the thrust plate 4 on the motor side includes a thrust bearing surface 18 of the thrust plate having an annular shape perpendicular to the rotation center axis. Further, the inner diameter side surfaces of the bearing sleeve 6 and the bearing sleeve 7 are opposed to the journal bearing surface 15 of the shaft portion in the radial direction, and the journal bearing surface 16 of the cylindrical bearing sleeve is formed in parallel with the rotation center axis. Including. The workpiece-side surface of the bearing sleeve 6 includes a thrust bearing surface 19 of the bearing sleeve that is annularly opposed to the thrust bearing surface 18 of the thrust plate and is perpendicular to the rotation center axis. Here, the rotation center axis indicates a straight line passing through the center of the cylindrical shaft portion 3, that is, a center line between the disc-shaped thrust plate 4 and the other thrust plate 5. The journal bearing surface 15 of the shaft portion and the journal bearing surface 16 of the bearing sleeve are formed with a journal bearing gap 17 of about 3 μm to 30 μm. The thrust bearing surface 18 of the thrust plate and the thrust bearing surface 19 of the bearing sleeve are formed with a thrust bearing gap 20 of about 3 μm or more and 50 μm or less separated.

  The journal bearing surface 16 of the bearing sleeve functions as a hydrostatic gas journal bearing that supports the rotating part 2 at least in the radial direction. The thrust bearing surface 19 of the bearing sleeve functions as a static pressure gas thrust bearing that supports the rotating portion 2 at least in the axial direction. That is, the housing 8 includes a support gas supply port 22 provided on the outer wall, and the support gas supply port 22 is connected to a support gas supply path 23 formed in the bearing sleeve 6, the bearing sleeve 7, and the housing 8. Yes. A support gas such as compressed air is supplied to a support gas supply port 22 from a support gas supply source such as an air compressor (not shown). The support gas is supplied to the journal bearing gap 17 via the support gas supply path 23 and the journal bearing supply throttle 24, and is also a thrust bearing via the support gas supply path 23 and the thrust bearing supply throttle 25. It is supplied to the gap 20. Thereby, the rotating part 2 is rotatably supported in a non-contact state with respect to the fixed part by the pressure of the supporting gas supplied to the journal bearing gap 17 and the thrust bearing gap 20.

  The gas flowing out from the journal bearing gap 17 and the thrust bearing gap 20 is discharged to the outside of the static pressure gas bearing spindle 1 through the exhaust passage 26, the exhaust passage 27, and the exhaust passage 28.

  The housing 8 includes a vent 29 provided in the outer wall. The air vent 29 is connected to a fixed-side air passage 30 formed in the bearing sleeve 6 and the housing 8. An annular vent groove 31 is provided on the work side surface of the bearing sleeve 6 concentrically with the rotation center axis, and the other end of the fixed-side vent path 30 is connected to the vent groove 31. That is, the fixed-side air passage 30 connects the air vent 29 and the air vent 31. The thrust plate 4 has a rotation side air passage 32. One end of the rotation side air passage 32 is connected to a position facing the air groove 31 on the motor side surface of the thrust plate 4. The other end of the rotation side air passage 32 is connected to an opening 33 provided on the workpiece side surface of the thrust plate 4. That is, the rotation-side air passage 32 communicates the air groove 31 and the opening 33. The object fixing means can be connected to the opening 33 or a gas passage (not shown) connected to the opening 33.

  Then, gas for changing the gas pressure in the object fixing means between the vent 29 and the object fixing means via the fixed side air passage 30, the ventilation groove 31, the rotation side air passage 32, and the opening 33. Circulate. That is, the air vent 29 and the object fixing means can be communicated with each other via the fixed side air passage 30 and the rotation side air passage 32, and gas can be circulated between the air vent 29 and the object fixing means. .

  Next, the operation of the static pressure gas bearing spindle 1 according to the first embodiment will be described. In FIG. 1, when power is supplied from a power source (not shown) to the motor stator 10, a driving force for rotating the motor rotor 9 about the axis is generated. Thereby, the rotating part 2 pivotally supported with respect to the fixed part rotates together with the motor rotor 9 relative to the fixed part.

  Further, when a negative pressure source such as a vacuum pump (not shown) connected to the vent hole 29 or a positive pressure source such as a compressor is operated, the fixed-side vent path 30 and the rotary-side vent path 32 are connected via the vent hole 29. The internal gas pressure changes.

  For example, when a negative pressure source is connected to the vent hole 29, the inside of the fixed side air passage 30 and the rotation side air passage 32 is depressurized by operating the negative pressure source. Therefore, the opening 33 connected to the end of the rotation side air passage 32 is decompressed. At this time, the object is adsorbed and fixed by bringing the object into contact with the opening 33 or a gas passage (not shown) connected to the opening 33. A workpiece such as a workpiece, an inspection object, or a tool can be fixed to the workpiece side surface of the thrust plate 4 by the vacuum chuck mechanism that functions in this manner.

  As another example, when a positive pressure source is connected to the vent hole 29, the inside of the fixed side air passage 30 and the rotation side air passage 32 is pressurized by operating the positive pressure source. Therefore, the opening 33 to which the end of the rotation side air passage 32 is connected is pressurized. At this time, by connecting the centering holding device to the opening 33 or a gas passage (not shown) connected to the opening 33, the piston is moved by pressurization, and a plurality of clamp pins are attached via the taper portion provided on the piston. The disc is centered and held by pushing it in the radial direction and bringing the clamp pin into contact with the inner diameter surface of the disc. With the centering and holding device functioning in this manner, the center of a perforated disk such as an optical disk or a magnetic disk can be aligned with the rotation center axis.

  In this case, the thrust plate 4 is provided with a rotation-side air passage 32 whose one end is connected to the motor-side surface of the thrust plate 4, so a vacuum chuck mechanism for adsorbing and fixing an object using negative pressure, and positive pressure are used. Therefore, in an object fixing means such as a centering holding device for centering a disk, it is not necessary to provide a conventional ventilation sleeve in order to circulate a gas for changing the gas pressure. Therefore, the shaft of the ventilation sleeve is compared with the conventional hydrostatic gas bearing spindle without reducing the axial length of the bearing sleeve 6 and the bearing sleeve 7, that is, the axial length of the journal bearing surface 16 of the bearing sleeve. The length of the shaft portion 3, that is, the length of the rotating portion 2 in the axial direction can be reduced by the length in the direction.

  In addition, the fixed-side air passage 30 and the rotation-side air passage 32 communicate with each other via the annular ventilation groove 31 provided concentrically with the rotation center axis. Even if the relative positional relationship with the fixed-side air passage 30 changes, the fixed-side air passage 30 and the rotation-side air passage 32 are always in communication. Therefore, while the rotating unit 2 is rotating, it is possible to perform operations such as processing and inspection of the object while maintaining a state in which the object fixing means functions stably. Further, since the fixed-side air passage 30 and the rotation-side air passage 32 only need to communicate with the air-groove 31, the end of the fixed-side air passage 30 and the end of the rotation-side air passage 32 are accurately opposed to each other. Even if it is not disposed at a position, the fixed-side air passage 30 and the rotation-side air passage 32 can be communicated with each other as long as they are within the width of the air groove 31. Therefore, the processing accuracy of the stationary-side air passage 30 and the rotation-side air passage 32 can be relaxed within the range of the width of the ventilation groove 31, and the influence of the processing accuracy on the performance of the object fixing means can be reduced.

  FIG. 2 is a schematic partial cross-sectional view showing a modified example in the vicinity of region II in FIG. In FIG. 2, the position where the fixed side air passage 30 is projected on the workpiece side surface of the bearing sleeve 6 and the end of the rotation side air passage 32 on the motor side surface of the thrust plate 4 are not located opposite to each other. Yes. However, the stationary side air passage 30 is connected to the air groove 31, and the rotation side air passage 32 faces the air groove 31. Therefore, the vent 29 and the opening 33 connected to the object fixing means communicate with each other through the fixed-side vent 30, the vent 31, and the rotation-side vent 32. A gas for changing the gas pressure in the object fixing means can be circulated between the object fixing means.

  Note that when the gas pressure inside the fixed-side air passage 30 and the rotation-side air passage 32 is changed, the bearing reaction force changes with the change in the gas pressure in the thrust bearing gap 20, and the rotating portion 2 is pivoted. It is necessary to suppress displacement in the direction. Therefore, in FIG. 1, a circumferential groove 34 is provided on the outer peripheral side of the position of the ventilation groove 31 on the workpiece side surface of the bearing sleeve 6. The circumferential groove 34 is connected to one end portion of the exhaust passage 26 and communicates with the outside of the static pressure gas bearing spindle 1 through the exhaust passage 26 and the exhaust passage 27. Thereby, the circumferential groove 34 is always kept at atmospheric pressure. In addition, a seal surface 36 is provided between the ventilation groove 31 and the circumferential groove 34 on the workpiece side surface of the bearing sleeve 6. The seal surface 36 and the motor side surface of the thrust plate 4 are formed with a seal gap 35 of about 3 μm or more and 50 μm or less equivalent to the thrust bearing gap 20.

  The circumferential groove 34 and the seal gap 35 can prevent the gas pressure in the thrust bearing gap 20 from changing even when pressure or negative pressure is supplied to the ventilation groove 31. That is, in FIG. 1, since the outer peripheral part of the thrust plate 4 is located outside the static pressure gas bearing spindle 1, it is always kept at atmospheric pressure. The circumferential groove 34 communicates with the outside of the static pressure gas bearing spindle 1 as described above, and a fine seal gap 35 equivalent to the thrust bearing gap 20 is provided between the ventilation groove 31 and the circumferential groove 34. Yes. Therefore, even when positive pressure or negative pressure is supplied to the fixed-side air passage 30 and the gas pressure inside the ventilation groove 31 changes, gas leakage is limited by the seal gap 35, and the inside of the circumferential groove 34. Is always maintained at atmospheric pressure and does not affect the gas pressure in the thrust bearing gap 20. Therefore, the gas pressure in the thrust bearing gap 20 can be stabilized by making the pressure of the supporting gas such as compressed air supplied from the outside to the thrust bearing gap 20 through the thrust bearing air supply restrictor 25 constant. . Therefore, it is possible to keep the bearing reaction force of the static pressure gas thrust bearing constant and to prevent the rotating portion 2 from being displaced in the axial direction.

  The ventilation groove 31 may be provided on the workpiece side surface of the bearing sleeve 6 as shown in FIG. 1, that is, on a plane including the thrust bearing surface 19 of the bearing sleeve in the fixed portion, and the motor side surface of the thrust plate 4. That is, you may provide on the plane in which the thrust bearing surface 18 of the thrust plate in a rotation part is included. Further, the ventilation groove 31 can be provided on both the workpiece side surface of the bearing sleeve 6 and the motor side surface of the thrust plate 4.

  The ventilation groove 31 is formed on the workpiece side surface of the annular bearing sleeve 6 or on the motor side surface of the thrust plate 4, as shown in FIG. The sleeve 6 may be provided at a position away from the inner diameter side surface of the sleeve 6 by a distance within 20% of the outer diameter of the thrust bearing surface 19 of the bearing sleeve. Further, it is provided in the vicinity of the outer peripheral end, that is, in the vicinity of the outer peripheral portion of the thrust plate 4 (for example, a position that is separated from the outer diameter side surface of the bearing sleeve 6 by a distance within 20% of the outer diameter of the thrust bearing surface 19 of the bearing sleeve). Also good. In any case, the circumferential groove 34 is formed between the ventilation groove 31 and the thrust bearing surface 19 of the bearing sleeve (when the ventilation groove 31 is provided on the motor side surface of the thrust plate 4, The gas pressure in the thrust bearing gap 20 can be stabilized by disposing it between the end of the fixed-side air passage 30 and the thrust bearing surface 19 of the bearing sleeve. Therefore, stable bearing performance can be obtained.

(Embodiment 2)
FIG. 3 is a schematic cross-sectional view showing the configuration of the static pressure gas bearing spindle according to the second embodiment which is an embodiment of the present invention. The static pressure gas bearing spindle 1 of the second embodiment and the static pressure gas bearing spindle 1 of the first embodiment described above basically have the same configuration. However, in the second embodiment, the vicinity of the thrust bearing surface 39 of the other bearing sleeve including the motor side surface of the bearing sleeve 7 facing the workpiece side surface of the other thrust plate 5 is configured as shown in FIG. This is different from the first embodiment.

  Specifically, in FIG. 3, this hydrostatic gas bearing spindle 1 includes another thrust plate 5 in which a rotating portion 2 is joined to an end face of a shaft portion 3 and has a larger diameter than the shaft portion 3. The other thrust plate 5 is formed at a distance from the thrust plate 4 in the axial direction, and is disposed to face the thrust plate 4. The motor side surface of the bearing sleeve 7 facing the workpiece side surface of the other thrust plate 5 includes a thrust bearing surface 39 of the other bearing sleeve having an annular shape perpendicular to the rotation center axis. The thrust bearing surface 39 of the other bearing sleeve functions as another hydrostatic gas thrust bearing that supports the rotating part 2 at least in the axial direction. That is, the fixed portion is axially spaced from the thrust bearing surface 19 of the bearing sleeve included in the workpiece side surface of the bearing sleeve 6 and the thrust bearing surface 19 of the bearing sleeve included in the motor side surface of the bearing sleeve 7. And a thrust bearing surface 39 of another bearing sleeve to be formed. The thrust bearing surface 19 of the bearing sleeve functions as a static pressure gas thrust bearing, and the thrust bearing surface 39 of the other bearing sleeve is another static pressure gas thrust bearing that is formed at an interval in the axial direction. Functions as a pressurized gas thrust bearing. The rotating part 2 is supported in the axial direction by forces opposite to each other generated in the static pressure gas thrust bearing and other static pressure gas thrust bearings.

  Then, another annular groove 40 is provided on the motor side surface of the bearing sleeve 7 concentrically with the rotation center axis. The other end of the fixed side air passage 41 formed in the bearing sleeve 7 and the housing 8 is connected to the fixed side air passage 30 and the other end is connected to the other air groove 40. Thereby, the vent hole 29 and the other ventilation groove 40 are communicated with each other via the fixed side ventilation path 30 and the other fixed side ventilation path 41. In addition, the ventilation groove 31 and the other ventilation groove 40 communicate with each other via the fixed-side ventilation path 30 and the other fixed-side ventilation path 41. That is, the fixed portion has a ventilation groove communication path that communicates the ventilation groove 31 with the other ventilation groove 40.

  Next, the operation of the static pressure gas bearing spindle 1 according to the second embodiment will be described. The static pressure gas bearing spindle 1 of the second embodiment and the static pressure gas bearing spindle 1 of the first embodiment described above operate basically in the same manner. However, since the static pressure gas bearing spindle 1 according to the second embodiment has the other ventilation groove 40 and the other stationary-side ventilation passage 41 as described above, the ventilation hole is used to make the object fixing means function. When a positive pressure source or a negative pressure source connected to 29 is operated and positive pressure or negative pressure is supplied through the vent 29, the fixed-side vent passage 30 and the other fixed-side vent passage 41, the vent groove 31. And the other ventilation groove 40 are always equal in pressure. Therefore, it is possible to prevent the rotating unit 2 from being displaced in the axial direction.

  That is, in FIG. 3, the rotating portion 2 is supported in the axial direction by a balance of bearing reaction forces in opposite directions generated in the static pressure gas thrust bearing and other static pressure gas thrust bearings. In such a configuration of the hydrostatic gas bearing spindle 1, if only the ventilation groove 31 is provided on the workpiece-side surface of the bearing sleeve 6, a negative pressure or a centering holding device for functioning the vacuum chuck mechanism functions. As the positive pressure is supplied and the pressure in the ventilation groove 31 changes, an axial force is generated. Therefore, the rotating part 2 may be displaced in the axial direction to a position where the bearing reaction force is balanced with the axial force.

  On the other hand, another ventilation groove 40 is provided on the motor side surface of the bearing sleeve 7, and the ventilation hole 29 and the ventilation groove 31 are communicated with each other via the stationary side ventilation path 30. In addition, the vent 29 and the other ventilation groove 40 are configured to communicate with each other via a part of the fixed-side ventilation path 30 and the other fixed-side ventilation path 41. At this time, the area of the ventilation groove 31 on the workpiece side surface of the bearing sleeve 6 and the area of the other ventilation groove 40 on the motor side surface of the bearing sleeve 7 can be made equal. For example, the other ventilation groove 40 can have the same dimensions as the ventilation groove 31. Thereby, when operating the positive pressure source or the negative pressure source connected to the vent hole 29 in order to make the object fixing means function, equal pressure is simultaneously generated in the vent groove 31 and the other vent grooves 40. For example, when the positive pressure source is operated, a force to push the thrust plate 4 to the work side is generated by the pressurization of the ventilation groove 31, while the other thrust plate 5 is pushed to the motor side by the pressurization of the other ventilation groove 40. Force is generated. Since the area of the ventilation groove 31 on the workpiece side surface of the bearing sleeve 6 and the area of the other ventilation groove 40 on the motor side surface of the bearing sleeve 7 are provided to be equal, a force having the same size and opposite direction is applied. It acts on the rotating part 2. Therefore, it is possible to prevent the rotating unit 2 from being displaced in the axial direction.

  Similar to the ventilation groove 31, the other ventilation groove 40 is provided on the motor side surface of the bearing sleeve 7, that is, on the plane including the thrust bearing surface 39 of the other bearing sleeve in the fixed portion as shown in FIG. Alternatively, it may be provided on a work surface of another thrust plate 5, that is, on a plane including a surface facing the thrust bearing surface 39 of another bearing sleeve in the rotating portion. Further, another ventilation groove 40 can be provided on both the motor side surface of the bearing sleeve 7 and the workpiece side surface of the other thrust plate 5. Further, the other ventilation groove 40 is formed on the motor-side surface of the annular bearing sleeve 7 or on the workpiece-side surface of the other thrust plate 5, as shown in FIG. It may be provided in the vicinity of the outer peripheral end, that is, in the vicinity of the outer peripheral portion of another thrust plate 5.

(Embodiment 3)
FIG. 4 is a schematic cross-sectional view showing a configuration of a static pressure gas bearing spindle according to the third embodiment which is an embodiment of the present invention. The static pressure gas bearing spindle 1 according to Embodiment 3 and the static pressure gas bearing spindle 1 according to Embodiment 1 described above basically have the same configuration. However, the third embodiment is different from the first embodiment in that the vicinity of the thrust plate 4 is configured as shown in FIG.

  Specifically, in FIG. 4, the static pressure gas bearing spindle 1 includes a thrust bearing member 43 that faces the workpiece side surface of the thrust plate 4. The motor side surface of the thrust bearing member 43 includes a thrust bearing surface 44 of the thrust bearing member having an annular shape perpendicular to the rotation center axis. The thrust bearing surface 44 of the thrust bearing member functions as another hydrostatic gas thrust bearing that supports the rotating portion 2 at least in the axial direction. That is, the fixed portion is axially spaced from the thrust bearing surface 19 of the bearing sleeve included in the workpiece side surface of the bearing sleeve 6 and the thrust bearing surface 19 of the bearing sleeve included in the motor side surface of the thrust bearing member 43. And a thrust bearing surface 44 of a thrust bearing member formed in this manner. The thrust bearing surface 19 of the bearing sleeve functions as a static pressure gas thrust bearing, and the thrust bearing surface 44 of the thrust bearing member is another static pressure formed at an axial interval from the static pressure gas thrust bearing. Functions as a gas thrust bearing. The rotating part 2 is supported in the axial direction by forces opposite to each other generated in the static pressure gas thrust bearing and other static pressure gas thrust bearings.

  Then, another annular groove 45 is provided on the motor side surface of the thrust bearing member 43 concentrically with the rotation center axis. The ventilation groove communication passage 46 formed in the thrust plate 4 has one end connected to the ventilation groove 31 and the other end connected to the other ventilation groove 45. That is, the vent hole 29 and the vent groove 31 are communicated with each other via the fixed-side vent path 30, and the vent groove 31 and the other vent groove 45 are communicated with each other via the vent groove communicating path 46.

  Next, the operation of the static pressure gas bearing spindle 1 according to the third embodiment will be described. The static pressure gas bearing spindle 1 of the third embodiment and the static pressure gas bearing spindle 1 of the first embodiment described above operate basically in the same manner. However, as described above, the static pressure gas bearing spindle 1 according to the third embodiment has the other ventilation groove 45 and the ventilation groove communication path 46 that communicates the ventilation groove 31 and the other ventilation groove 45. Therefore, when a positive pressure source or a negative pressure source connected to the vent 29 is operated in order to make the object fixing means function, positive pressure or negative pressure is supplied through the vent 29 and the fixed-side vent passage 30. Moreover, the pressures in the ventilation groove 31 and the other ventilation grooves 45 are always equal. Therefore, it is possible to prevent the rotating unit 2 from being displaced in the axial direction.

  That is, in FIG. 4, the rotating portion 2 is supported in the axial direction by a balance of bearing reaction forces in opposite directions generated in the static pressure gas thrust bearing and other static pressure gas thrust bearings. In such a configuration of the hydrostatic gas bearing spindle 1, if only the ventilation groove 31 is provided on the workpiece-side surface of the bearing sleeve 6, a negative pressure or a centering holding device for functioning the vacuum chuck mechanism functions. As the positive pressure is supplied and the pressure in the ventilation groove 31 changes, an axial force is generated. Therefore, the rotating part 2 may be displaced in the axial direction to a position where the bearing reaction force is balanced with the axial force.

  On the other hand, another ventilation groove 45 is provided on the motor side surface of the thrust bearing member 43. The ventilation groove 31 is configured to communicate with another ventilation groove 45 through the ventilation groove communication path 46. At this time, the area of the ventilation groove 31 on the workpiece side surface of the bearing sleeve 6 and the area of the other ventilation groove 45 on the motor side surface of the thrust bearing member 43 can be made equal. For example, the other ventilation grooves 45 can have the same dimensions as the ventilation grooves 31. Thereby, when operating the positive pressure source or the negative pressure source connected to the vent hole 29 in order to make the object fixing means function, equal pressure is simultaneously generated in the vent groove 31 and the other vent grooves 45. For example, when the positive pressure source is operated, a force that pushes the thrust plate 4 to the work side is generated by the pressurization of the ventilation groove 31, while a force that pushes the thrust plate 4 to the motor side by the pressurization of the other ventilation groove 45. appear. Since the area of the ventilation groove 31 on the workpiece side surface of the bearing sleeve 6 and the area of the other ventilation groove 45 on the motor side surface of the thrust bearing member 43 are provided to be equal, the force is equal in size and opposite in direction. Acts on the rotating part 2. Therefore, it is possible to prevent the rotating unit 2 from being displaced in the axial direction.

  Similar to the ventilation groove 31, the other ventilation groove 45 is provided on the motor side surface of the thrust bearing member 43, that is, on a plane including the thrust bearing surface 44 of the thrust bearing member in the fixed portion as shown in FIG. Alternatively, the thrust plate 4 may be provided on a plane including the workpiece side surface, that is, the surface of the rotating portion facing the thrust bearing surface 44 of the thrust bearing member. Further, another ventilation groove 45 can be provided on both the motor side surface of the thrust bearing member 43 and the workpiece side surface of the thrust plate 4.

  Further, the other ventilation groove 45 is formed on the motor side surface of the annular thrust bearing member 43 or the workpiece side surface of the thrust plate 4 in the vicinity of the inner peripheral side end portion, that is, in the vicinity of the shaft portion 3 as shown in FIG. It may be provided, or may be provided in the vicinity of the outer peripheral side end, that is, in the vicinity of the outer peripheral portion of the thrust plate 4. In FIG. 4, another circumferential groove 47 is provided between the other ventilation groove 45 and the thrust bearing surface 44 of the thrust bearing member on the motor side surface of the thrust bearing member 43. In addition, a circumferential groove communication passage 48 that communicates the circumferential groove 34 with another circumferential groove 47 is formed in the thrust plate 4. Accordingly, the other circumferential groove 47 communicates with the outside of the static pressure gas bearing spindle 1 through the circumferential groove communication path 48, the circumferential groove 34, the exhaust path 26, and the exhaust path 27. The circumferential groove 47 is always kept at atmospheric pressure. Therefore, in the case where the other ventilation groove 45 is provided in the vicinity of the inner peripheral side end portion or the outer peripheral side end portion, the other circumferential groove 47 is provided with the other ventilation groove 45 and the thrust bearing surface 44 of the thrust bearing member. (When the other ventilation groove 45 is provided on the workpiece side surface of the thrust plate 4, the position where the other ventilation groove 45 is projected on the motor side surface of the thrust bearing member 43 and the thrust bearing surface 44 of the thrust bearing member). The gas pressure in the gap between the thrust bearing surface 44 of the thrust bearing member and the workpiece side surface of the thrust plate 4 can be stabilized. Therefore, stable bearing performance can be obtained.

(Embodiment 4)
FIG. 5 is a schematic cross-sectional view showing a configuration of a static pressure gas bearing spindle according to a fourth embodiment which is an embodiment of the present invention. The static pressure gas bearing spindle 1 of the fourth embodiment and the static pressure gas bearing spindle 1 of the second embodiment described above basically have the same configuration. However, in the fourth embodiment, the vicinity of the thrust bearing surface 39 of the other bearing sleeve, which is included in the motor side surface of the bearing sleeve 7 to which the workpiece side surface of the other thrust plate 5 faces, is configured as shown in FIG. This is different from the second embodiment.

  Specifically, in FIG. 5, the static pressure gas bearing spindle 1 includes another vent 50 provided on the outer wall of the housing 8. The other vent 50 is connected to another fixed-side vent passage 51 formed in the bearing sleeve 7 and the housing 8. Further, another annular groove 52 is provided on the workpiece side surface of the other thrust plate 5 concentrically with the rotation center axis, and the other end of the other stationary side air passage 51 is formed on the bearing sleeve 7. It connects with the position which opposes the other ventilation groove | channel 52 in the motor side surface. That is, the other fixed side air passage 51 communicates the other vent 50 and the other vent groove 52. The other thrust plate 5 has another rotation side air passage 53. One end of the other rotation side air passage 53 is connected to the other air groove 52. The other end of the other rotation side air passage 53 is connected to another opening 54 provided on the workpiece side surface of the thrust plate 4. In other words, the other rotation-side ventilation path 53 communicates the other ventilation groove 52 and the other opening 54. The object fixing means can be connected to another opening 54 or a gas passage (not shown) connected to the other opening 54. Then, the object is fixed between the other air vent 50 and the object fixing means via the other fixed side air passage 51, the other air groove 52, the other rotation side air passage 53, and the other opening 54. Gas for changing the gas pressure is circulated in the means. That is, the other vent 50 and the object fixing means are communicated with each other via the other fixed-side vent path 51 and the other rotation-side vent path 53, and between the other vent 50 and the object fixing means. The gas can be circulated.

  Next, the operation of the static pressure gas bearing spindle 1 according to the fourth embodiment will be described. The static pressure gas bearing spindle 1 of the fourth embodiment and the static pressure gas bearing spindle 1 of the second embodiment described above operate basically in the same manner. However, as described above, the static pressure gas bearing spindle 1 according to the fourth embodiment includes the other vent 50, the other fixed-side vent passage 51 that communicates the other vent 50 and the other vent groove 52, and Another rotation-side ventilation path 53 that communicates the other ventilation groove 52 and the other opening 54 is provided. Therefore, the gas pressure supplied from the vent 29 to the object fixing means via the fixed-side vent passage 30, the vent groove 31, the rotation-side vent passage 32, and the opening 33, and the other vent-side 50 to the other fixed-side. Other gas pressures supplied to the object fixing means via the ventilation path 51, the other ventilation groove 52, the other rotation-side ventilation path 53, and the other opening 54 are set to arbitrary pressures for each ventilation port. can do. That is, the gas pressure supplied from the vent 29 and the gas pressure supplied from the other vent 50 can be set to the same pressure setting, or can be set to different pressure settings. For example, after the vent 29 is connected to a positive pressure source and the centering device is operated to accurately determine the position of the object relative to the rotating unit 2, the other vent 50 is connected to the negative pressure source, and the vacuum chuck The object can be fixed by operating the mechanism.

  At this time, a rotation-side air passage 32 having one end connected to the motor-side surface of the thrust plate 4 is provided in the thrust plate 4, and the other end is connected to the work-side surface of the other thrust plate 5. A side air passage 53 is provided in the other thrust plate 5. Accordingly, the rotating portion is equivalent to the axial length of the two ventilation sleeves in comparison with the conventional static pressure gas bearing spindle that requires two ventilation sleeves to function the centering device and the vacuum chuck mechanism, respectively. The axial length of 2 can be shortened.

  Similar to the ventilation groove 31, the other ventilation groove 52 has a surface facing the workpiece side surface of the other thrust plate 5, that is, the surface facing the thrust bearing surface 39 of the other bearing sleeve in the rotating portion 2, as shown in FIG. It may be provided on the included plane, or may be provided on the plane on the motor side surface of the bearing sleeve 7, that is, on the plane including the thrust bearing surface 39 of another bearing sleeve in the fixed portion. Further, another ventilation groove 52 can be provided on both the workpiece side surface of the other thrust plate 5 and the motor side surface of the bearing sleeve 7. Further, the other ventilation groove 52 is formed on the motor side surface of the annular bearing sleeve 7 or the workpiece side surface of the other thrust plate 5 in the vicinity of the inner peripheral side end as shown in FIG. It may be provided in the vicinity of the outer peripheral end, that is, in the vicinity of the outer peripheral portion of another thrust plate 5.

  In order to supply a plurality of gas pressures to the object fixing means, a plurality of ventilation systems including a ventilation hole, a fixed-side ventilation path, a ventilation groove, and a rotation-side ventilation path may be provided. Therefore, a plurality of ventilation grooves can be arranged in a radial direction on a plane including the thrust bearing surface of one bearing sleeve or on a plane including the thrust bearing surface of one thrust plate.

  The embodiment disclosed this time should be considered as 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.

  The static pressure gas bearing spindle of the present invention includes a static pressure provided with an object fixing means for fixing a workpiece, an inspection object, a tool or the like to a rotating part using a gas pressure, such as a vacuum chuck mechanism and a centering holding device. It can be applied particularly advantageously to gas bearing spindles.

1 is a schematic cross-sectional view showing a configuration of a static pressure gas bearing spindle of a first embodiment. It is the schematic fragmentary sectional view which expanded and showed the area | region of the modification near the area | region II of FIG. 6 is a schematic cross-sectional view showing a configuration of a static pressure gas bearing spindle of a second embodiment. FIG. FIG. 6 is a schematic cross-sectional view showing a configuration of a static pressure gas bearing spindle according to a third embodiment. FIG. 6 is a schematic cross-sectional view showing a configuration of a static pressure gas bearing spindle according to a fourth embodiment. It is a schematic sectional drawing which shows the structure of the conventional static pressure gas bearing spindle.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Static pressure gas bearing spindle, 2 Rotating part, 3 Shaft part, 4 Thrust board, 5 Other thrust board, 6 Bearing sleeve, 7 Bearing sleeve, 8 Housing, 9 Motor rotor, 10 Motor stator, 11 Motor housing, 12 Rotary encoder , 13 Workpiece side direction, 14 Motor side direction, 15 Shaft journal bearing surface, 16 Bearing sleeve journal bearing surface, 17 Journal bearing clearance, 18 Thrust plate thrust bearing surface, 19 Bearing sleeve thrust bearing surface, 20 Thrust Bearing clearance, 22 Support gas supply port, 23 Support gas supply channel, 24 Journal bearing supply throttle, 25 Thrust bearing supply throttle, 26 Exhaust passage, 27 Exhaust passage, 28 Exhaust passage, 29 Vent, 30 Fixed side Ventilation path, 31 Ventilation groove, 32 Rotating side ventilation path, 3 Opening, 34 Circumferential groove, 35 Seal gap, 36 Seal surface, 39 Thrust bearing surface of other bearing sleeve, 40 Other ventilation groove, 41 Other fixed side air passage, 43 Thrust bearing member, 44 Thrust of thrust bearing member Bearing surface, 45 Other vent groove, 46 Vent groove communication path, 47 Other circumferential groove, 48 Circumferential groove communication path, 50 Other vent, 51 Other fixed side vent path, 52 Other vent groove, 53 Other rotation side air passage, 54 Other opening, 101 Hydrostatic gas bearing spindle, 102 Rotating part, 103 Shaft part, 104 Thrust plate, 105 Other thrust plate, 106 Bearing sleeve, 107 Bearing sleeve, 108 Venting sleeve, 109 Housing, 110 Hydrostatic Gas Journal Bearing, 111 Hydrostatic Gas Thrust Bearing, 112 Supporting Gas Supply Port, 113 Supporting Gas Supply Path 114 journal shaft receiving air aperture, 115 stop thrust receiving air, 116 exhaust passage 117 exhaust passage 118 vents 119 fixed air passage, 120 rotating air passage, 121 openings.

Claims (5)

In a static pressure gas bearing spindle comprising an object fixing means operating by gas pressure,
A rotating part including a cylindrical journal bearing surface parallel to the rotation center axis and an annular thrust bearing surface perpendicular to the rotation center axis;
A fixing part for supporting the rotating part,
The fixed portion is opposed to the journal bearing surface in the radial direction, and the hydrostatic gas journal bearing that supports the rotating portion at least in the radial direction is opposed to the thrust bearing surface in the axial direction, and the rotation is performed. A hydrostatic gas thrust bearing that supports at least the axial portion,
A circle concentrically with the rotation center axis on at least one of a plane including the thrust bearing surface in the rotating portion and a plane including a surface facing the thrust bearing surface in the fixed portion. An annular vent groove is provided,
The fixed portion has a vent provided in an outer wall of the fixed portion, and a fixed-side air passage communicating the vent and the vent groove,
The rotating part has a rotation-side air passage that communicates the ventilation groove and the object fixing means,
A gas for changing the gas pressure in the object fixing means is circulated between the object fixing means and the object through the fixed side air passage and the rotation side air passage. And a hydrostatic gas bearing spindle. The fixed portion includes the static pressure gas thrust bearing, and another static pressure gas thrust bearing formed at an interval in the axial direction from the static pressure gas thrust bearing,
The rotating portion is supported in the axial direction by forces opposite to each other generated in the hydrostatic gas thrust bearing and the other hydrostatic gas thrust bearing,
On the plane including another thrust bearing surface of the annular shape perpendicular to the rotation center axis facing the other static pressure gas thrust bearing in the rotating portion, and facing the other thrust bearing surface in the fixed portion On the plane including the surface to be provided, at least any one of the annular grooves on the concentric circle with the rotation center axis is provided,
2. The hydrostatic gas bearing spindle according to claim 1, further comprising a ventilation groove communication path that communicates the ventilation groove with the other ventilation groove. 3.   The said ventilation groove communicating path is provided in the said fixing | fixed part, One end part is connected with the said fixed side ventilation path, The other end part is connected with the said other ventilation groove, The 2nd characterized by the above-mentioned. Static pressure gas bearing spindle as described in.   The static pressure gas bearing spindle according to claim 2, wherein the ventilation groove communication path is provided in the rotating part. The fixed portion includes the static pressure gas thrust bearing, and another static pressure gas thrust bearing formed at an interval in the axial direction from the static pressure gas thrust bearing,
The rotating portion is supported in the axial direction by forces opposite to each other generated in the hydrostatic gas thrust bearing and the other hydrostatic gas thrust bearing,
On the plane including the thrust bearing surface in the rotating portion, on the plane including the surface facing the thrust bearing surface in the fixed portion, and facing the other hydrostatic gas thrust bearing in the rotating portion. At least one of the plane including the other thrust bearing surface in the annular shape perpendicular to the rotation center axis and the plane including the surface facing the other thrust bearing surface in the fixed portion, Provide another annular groove on the concentric circle with the rotation center axis,
The fixed portion has another vent provided in the outer wall of the fixed portion, and another fixed-side vent passage communicating the other vent and the other vent groove,
The rotating part has another rotating side air passage that communicates the other ventilation groove and the object fixing means,
Gas for changing the gas pressure in the object fixing means between the other air vent and the object fixing means via the other fixed side air passage and the other rotation side air passage. The hydrostatic gas bearing spindle according to claim 1, wherein

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