JP5857537B2 - Air spindle - Google Patents

Description

  The present invention relates to an air spindle (static pressure gas which is disposed between a shaft, a housing, and a shaft and the housing and rotatably supports a rotating body which is one of the shaft and the housing with respect to a fixed body which is the other. And a rotating device having a bearing.

  In a general air spindle, a static pressure gas bearing is fixed to a fixed body, and has an axial bearing surface and a radial bearing surface between the rotating body. That is, the static pressure gas bearing cannot move in the axial direction. Therefore, when the rotating body expands and extends in the axial direction as the temperature of the air spindle rises, the gap (axial gap) between the axial bearing surface of the hydrostatic gas bearing and the axial bearing surface of the rotating body widens, which is good The bearing performance may not be achieved.

  In Patent Document 1, in order to prevent a bearing gap from being lost when a temperature difference occurs between a housing that is a rotating body of an air spindle and a support shaft that is a non-rotating body, the support shaft is made of aluminum. In this case, it is described that the radial static pressure gas bearing is made of carbon graphite and the housing is made of a composite material of carbon fiber and carbon. In the air spindle described in Patent Document 1, the rotating body has a projecting portion (thrust runner) in the radial direction, and thrust hydrostatic gas bearings are arranged on both sides of the thrust runner in the axial direction. .

  In Patent Document 2, in order to absorb external force, vibration, resonance, and the like received by the rotating shaft, the rotating shaft and the bearing member (hydrostatic gas bearing) move together when external force or vibration occurs. A rotary atomizing electrostatic coating device is described. In the device described in Patent Document 2, the rotating body (rotating shaft) has a projecting portion (flange portion) in the radial direction, and static pressure gas bearings are disposed on both sides of the flange portion in the axial direction. ing. A static pressure gas bearing is attached to a fixed body (synthetic resin housing) via an elastic support member such as an O-ring.

JP-A-9-158950 Japanese Patent Laid-Open No. 9-294942

  An object of the present invention is to provide an air spindle capable of exhibiting good bearing performance by a static pressure gas bearing even when a rotating body expands and extends in the axial direction as the temperature rises.

In order to solve the above-described problems, an air spindle of the present invention includes a shaft that is a fixed body, a housing that is a rotating body, an end member that is inserted into the shaft and fixed to an end portion in the axial direction of the housing, is disposed between the shaft and said housing, said housing having a, a static gas bearing for rotatably supported with respect to said axis, the projection of the axis in the radial direction (direction perpendicular to the axis) has a section, the hydrostatic gas bearing, on opposite sides of a portion in the axial direction across said protruding portion of said shaft, mounted to be movable in the axial direction, the externally pressurized gas bearing, the end member and the opposite An axial bearing surface , a radial bearing surface facing the inner peripheral surface of the housing , and an axial end surface facing the axial end surface of the protruding portion , the hydrostatic gas bearing is formed of a cylindrical body, Internally extending in the axial direction A recovery hole that is branched from the exhaust path and extends in the radial direction of the shaft to reach the outer peripheral surface of the shaft, and the exhaust hole that communicates with the recovery hole radially connects the cylindrical body Gas introduction circumferential grooves are formed at positions on both sides of the exhaust hole in the axial direction of the inner circumferential surface of the cylindrical body, and the circumference of the outer peripheral portion of the shaft is formed as a through hole. the position of the groove, and wherein the air supply holes are formed Rukoto extending radially branched from the air supply passage.

In the air spindle of the present invention, since the static pressure gas bearing is mounted so as to be movable in the axial direction, even if the rotating body expands and extends in the axial direction as the temperature of the air spindle rises, the static pressure gas bearing A gap (axial gap) between the axial direction end face of the rotating body and the axial end face of the fixed body is held in an appropriate gap.
The static pressure gas bearing can be moved in the axial direction by being attached to the fixed body through, for example, an elastic support member or a labyrinth seal.

  According to the air spindle of the present invention, even when the rotating body expands and extends in the axial direction as the temperature rises, good bearing performance by the hydrostatic gas bearing can be exhibited.

It is sectional drawing which shows the air spindle of 1st Embodiment. It is the elements on larger scale of FIG. It is sectional drawing which shows the air spindle of 2nd Embodiment. It is sectional drawing which shows the air spindle of 3rd Embodiment. It is sectional drawing which shows the air spindle of 4th Embodiment.

Embodiments of the present invention will be described below.
[First Embodiment]
The air spindle of this embodiment is an example in which the shaft is a fixed body and the housing is a rotating body. As shown in FIGS. 1 and 2, a fixed shaft (fixed body) 1 and an elongated cylindrical housing (rotating body) 2 are used. A pair of static pressure gas bearings 3 disposed between the fixed shaft 1 and the housing 2, a pair of annular end members (rotating bodies) 4, and an O-ring (elastic support member) 5. It is configured.
The fixed shaft 1 has a projecting portion 1 a in the radial direction at a portion arranged in the central portion of the housing 2 in the axial direction. The pair of static pressure gas bearings 3 is formed of a cylindrical body, and is externally fitted to both side portions (bearing portions) 1b sandwiching the protruding portion 1a of the fixed shaft 1 in the axial direction.

As shown in FIG. 2, four circumferential grooves 11 are formed on the outer peripheral surface of the bearing portion 1 b of the fixed shaft 1. In addition, O-rings 5 are arranged in all the circumferential grooves 11. By these O-rings 5, a pair of static pressure gas bearings 3 are attached to the fixed shaft 1 so as to be movable in the axial direction.
The hydrostatic gas bearing 3 has a radial bearing surface 31 that faces the inner peripheral surface of the housing 2 and an axial end surface 32 that faces the end surfaces of the end member 4 and the protruding portion 1a. An exhaust hole 35 penetrating in the radial direction is formed in the axially central portion of the static pressure gas bearing 3. The exhaust holes 35 are formed at a plurality of locations in the circumferential direction. On the inner peripheral surface of the static pressure gas bearing 3, gas introduction peripheral grooves 36 are formed on both sides of the exhaust hole 35 in the axial direction. The circumferential groove 11 of the fixed shaft 1 is formed at positions on both sides of the circumferential groove 36 of the static pressure gas bearing 3.

An air supply path (gas supply path) 12 and an exhaust path (gas discharge path) 13 extending in the axial direction are formed inside the fixed shaft 1. A communication path (gas discharge path) 14 that branches from the exhaust path 13 and extends in the radial direction and reaches the outer peripheral surface of the protrusion 1 a is formed at the axial center position of the protrusion 1 a of the fixed shaft 1.
Inside the fixed shaft 1 and at the position of the exhaust hole 35 of the hydrostatic gas bearing 3, a recovery hole (gas discharge path) branched from the exhaust passage 13 and extending in the radial direction to reach the outer peripheral surface of the fixed shaft 1. 15 is formed. Inside the fixed shaft 1, an air supply hole (gas supply path) 12 a that branches from the air supply path 12 and extends in the radial direction is further formed at the position of the circumferential groove 36 of the static pressure gas bearing 3.

As shown in FIG. 2, the end member 4 includes a large diameter portion 41 having a contact surface with the axial end surface of the housing 2, a medium diameter portion 42 and a small diameter portion 43 inserted into the axial end portion of the housing 2. Consists of. The end member 4 has an exhaust hole 44 extending in the axial direction. The end member 4 has the fixed shaft 1 inserted therein and is fixed to both ends of the housing 2 in the axial direction. A surface facing the end surface of the small diameter portion 43 of the end member 4 is an axial bearing surface 32 a of the static pressure gas bearing 3. A gas discharge gap 6 exists between the outer peripheral surface of the small diameter portion 43 of the end member 4 and the inner peripheral surface of the housing 2.

In the air spindle of this embodiment, the pressurized gas introduced from the outside into the air supply path 12 of the fixed shaft 1 enters the inner peripheral groove 36 of the static pressure gas bearing 3 from the air supply hole 12a, and the static pressure gas bearing 3 Are supplied to the radial bearing surface 31 and the axial end surface 32. Thereby, the static pressure gas bearing 3 functions.
The gas that has passed through the radial bearing surface 31 and the axial end surface 32 is recovered from the exhaust hole 35 to the exhaust path 13 via the recovery hole 15. The gas collected in the exhaust passage 13 is discharged to the outside. Further, the gas that has passed through the axial end surface 32 ( axial bearing surface 32 a) on the end member 4 side is mainly discharged to the outside from the gas discharge gap 6 through the exhaust hole 44 of the end member 4.

According to the air spindle of this embodiment, since the static pressure gas bearing 3 is attached to the bearing portion 1b of the fixed shaft 1 so as to be movable in the axial direction by the O-ring 5, the housing (rotating body) is increased as the temperature rises. Even when 2 expands and extends in the axial direction, the axial bearing surface 32 a and the axial end surface 32 of the static pressure gas bearing 3, the end surface of the small diameter portion 43 of the end member (rotating body) 4, and the fixed shaft (fixed body) ) A gap (axial gap) with the end face of one protruding portion 1a is held in an appropriate gap. Therefore, the favorable bearing performance by the static pressure gas bearing 3 can be exhibited.

[Second Embodiment]
The air spindle of this embodiment is an example in which the shaft is a rotating body and the housing is a fixed body. As shown in FIG. 3, a shaft (rotating body) 7 and a cylindrical body (rotating body) externally fitted to the shaft 7 are used. 71, a pair of end members (rotating bodies) 72, a housing (fixed body) 8, a pair of static pressure gas bearings 9 disposed between the cylindrical body 71, the end members 72, and the housing 8, An O-ring (elastic support member) 5 is included.

The housing 8 has a shape having a radially projecting portion 82 on the inner peripheral surface of the central portion in the axial direction of the cylindrical portion 81. Two circumferential grooves 84 are formed on the inner peripheral surfaces (the inner peripheral surface of the cylindrical portion 81 where the protruding portions 82 are not formed) at both axial ends of the housing 8. The O-ring 5 is disposed in all the circumferential grooves 84. With these O-rings 5, a pair of static pressure gas bearings 9 are attached to the housing 8 so as to be movable in the axial direction.
The pair of static pressure gas bearings 9 is in the shape of a perforated disk and is disposed on both sides of the protruding portion 82 of the housing 8 in the axial direction. The static pressure gas bearing 9 has a radial bearing surface 91 that faces the outer peripheral surface of the cylindrical body 71, and an axial end surface 92 that faces the end surfaces of the end member 72 and the protruding portion 82. A gas introduction circumferential groove 96 is formed on the outer peripheral surface of the static pressure gas bearing 9.

  The housing 8 is connected to a first air supply path (gas supply path) 81 a extending in the axial direction of the cylindrical portion 81 and the first air supply path 81 a, and extends in the radial direction of the cylindrical portion 81 to A pair of second air supply paths (gas supply paths) 81b and exhaust paths (gas discharge paths) 83 reaching the inner peripheral surface are formed. The pair of second air supply passages 81 b are disposed at the positions of the circumferential grooves 96 of the pair of static pressure gas bearings 9. One second air supply path 81b opens at the outer peripheral surface of the cylindrical portion 81, and this opening serves as a female screw hole 81c for connecting the gas supply pipe. The exhaust passage 83 penetrates the axial center of the housing 8 (the position where the protruding portion 82 is formed) along the radial direction.

The outer diameter of the end member 72 is the same as the outer diameter of the static pressure gas bearing 9, and the inner diameter of the end member 72 is the same as the outer diameter of the shaft 7. The end member 72 is fixed to both axial end surfaces of the cylindrical body 71 with bolts.
In the air spindle of this embodiment, the pressurized gas introduced from the gas supply pipe connected to the female screw hole 81c of the housing 8 enters the outer peripheral groove 96 of the static pressure gas bearing 9 from the second air supply hole 81b. It is supplied to the radial bearing surface 91 and the axial end surface 92 of the static pressure gas bearing 9. Thereby, the static pressure gas bearing 9 functions. The gas that has passed through the radial bearing surface 91 and the axial end surface 92 passes between the cylindrical body 71 and the housing 8 and is discharged from the exhaust path 83 to the outside.

According to the air spindle of this embodiment, the static pressure gas bearing 9 is attached to the cylindrical portion 81 of the housing 8 so as to be movable in the axial direction by the O-ring 5. ) Even when 71 expands and extends in the axial direction, the axial bearing surface 92a and the axial end surface 92 of the static pressure gas bearing 9 and the projecting portion 82 of the end member (rotating body) 72 and the housing (fixed body) 8 are provided. A gap (axial gap) with the end face of the is maintained in an appropriate gap. Therefore, the favorable bearing performance by the static pressure gas bearing 9 can be exhibited.

[Third Embodiment]
In the first embodiment, the pair of static pressure gas bearings 3 are attached to the fixed shaft 1 so as to be movable in the axial direction by the O-ring 5. In this embodiment, instead of the O-ring 5, the labyrinth A seal 50 is used. Other points are the same as in the first embodiment.
As shown in FIG. 4, in the air spindle of this embodiment, labyrinth seals 50 are formed at four locations on the outer peripheral surface of the bearing portion 1 b of the fixed shaft 1. With these labyrinth seals 50, a pair of static pressure gas bearings 3 are attached to the fixed shaft 1 so as to be movable in the axial direction. The labyrinth seal 50 is formed at positions on both sides of the circumferential groove 36 of the static pressure gas bearing 3.

According to the air spindle of this embodiment, since the static pressure gas bearing 3 is attached to the bearing portion 1b of the fixed shaft 1 so as to be movable in the axial direction by the labyrinth seal 50, the housing (rotating body) is increased as the temperature rises. Even when 2 expands and extends in the axial direction, the axial bearing surface 32 a and the axial end surface 32 of the static pressure gas bearing 3, the end surface of the small diameter portion 43 of the end member (rotating body) 4, and the fixed shaft (fixed body) ) A gap (axial gap) with the end face of one protruding portion 1a is held in an appropriate gap. Therefore, the favorable bearing performance by the static pressure gas bearing 3 can be exhibited.

[Fourth Embodiment]
In the second embodiment, a pair of static pressure gas bearings 9 are attached to the housing 8 so as to be movable in the axial direction by the O-ring 5. In this embodiment, a labyrinth seal is used instead of the O-ring 5. 50 is used. The other points are the same as in the second embodiment.
As shown in FIG. 5, in the air spindle of this embodiment, the labyrinth is provided at each of two locations on the inner peripheral surface (the inner peripheral surface of the cylindrical portion 81 where the protruding portion 82 is not formed) at both axial ends of the housing 8. A seal 50 is formed. By these labyrinth seals 50, a pair of static pressure gas bearings 9 are attached to the housing 8 so as to be movable in the axial direction. The labyrinth seal 50 is formed at positions on both sides of the circumferential groove 96 of the static pressure gas bearing 9.

According to the air spindle of this embodiment, the static pressure gas bearing 9 is attached to the cylindrical portion 81 of the housing 8 so as to be movable in the axial direction by the labyrinth seal 50. ) Even if 71 expands and extends in the axial direction, the axial bearing surface 92a and the axial end surface 92 of the static pressure gas bearing 9 and the projecting portion 82 of the end member (rotating body) 72 and the housing (fixed body) 8 are provided. A gap (axial gap) with the end face of the is maintained in an appropriate gap. Therefore, the favorable bearing performance by the static pressure gas bearing 9 can be exhibited.

1 Fixed shaft (fixed body)
1a Protruding part of the fixed shaft (fixed body) 1b Bearing part of the fixed shaft (part other than the protruding part of the fixed body)
DESCRIPTION OF SYMBOLS 11 Circumferential groove 12 Air supply path 12a Air supply hole 13 Exhaust path 14 Communication path 15 Collection | recovery hole 2 Housing (rotating body)
3 Static pressure gas bearing 31 Radial bearing surface
32 Axial end face 32 a Axial bearing surface 35 Exhaust hole 36 Circumferential groove 4 End member (rotating body)
41 Large-diameter portion of end member 42 Medium-diameter portion of end member 43 Small-diameter portion of end member 44 Exhaust hole 5 O-ring (elastic support member)
50 Labyrinth seal 6 Gas exhaust gap 7 Shaft (Rotating body)
71 Cylindrical body (rotating body)
72 End member (rotating body)
8 Housing (fixed body)
81 Cylindrical portion of housing (fixed body) 81a Air supply path 81b Air supply path 81c Female screw hole 82 Projection of housing (fixed body) 83 Exhaust path 84 Circumferential groove 9 Hydrostatic gas bearing 91 Radial bearing surface
92 Axial end face 92 a Axial bearing face 96 Circumferential groove

Claims (3)

A shaft that is a fixed body, a housing that is a rotating body, an end member that is inserted into the shaft and fixed to an axial end of the housing, and
Is arranged between the shaft housing, and a hydrostatic gas bearing for rotatably supporting the housing relative to said axis,
Have
The shaft has a radial protrusion;
The hydrostatic gas bearing is on both sides of a portion in the axial direction across said protruding portion of said shaft, mounted to be movable in the axial direction,
The static pressure gas bearing has an axial bearing surface facing the end member, a radial bearing surface facing the inner peripheral surface of the housing , and an axial end surface facing the axial end surface of the protrusion ,
The static pressure gas bearing is a cylindrical body,
Inside the shaft, an air supply passage and an exhaust passage extending in the axial direction, and a recovery hole branched from the exhaust passage and extending in the radial direction of the shaft to reach the outer peripheral surface of the shaft,
An exhaust hole communicating with the recovery hole is formed as a through hole penetrating the cylindrical body in a radial direction,
A circumferential groove for introducing gas is formed at positions on both sides of the exhaust hole in the axial direction of the inner peripheral surface of the cylindrical body,
An air spindle in which an air supply hole branched from the air supply path and extending in the radial direction is formed at a position of the peripheral groove on the outer peripheral portion of the shaft .   The air spindle according to claim 1, wherein the static pressure gas bearing is attached to the fixed body via an elastic support member.   The air spindle according to claim 1, wherein the static pressure gas bearing is attached to the fixed body via a labyrinth seal.

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