JP3341853B2 - Hydrostatic bearing - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydrostatic gas bearing used for a high-speed rotary spindle or the like.

[0002]

2. Description of the Related Art Conventionally, a hydrostatic gas bearing is provided with a bearing portion facing an outer peripheral surface of a rotating shaft via a gap, and a bearing portion is provided with an air supply hole having a plurality of openings in an inner peripheral surface. An exhaust hole is provided in the vicinity of both ends of the portion, and by supplying a pressurized gas from an air supply hole, a static pressure is generated between the bearing portion and the rotating shaft, and the rotating shaft is supported by the static pressure. (See, for example, JP-A-63-186030,
49414).

[0003]

However, in the above configuration, when the rotating shaft and the inner peripheral surface of the bearing portion come into contact with each other due to an overload applied to the rotating shaft, the bearing portion is a rigid body so that there is no escape. However, there is a drawback that galling occurs and cannot be used as a bearing. SUMMARY OF THE INVENTION An object of the present invention is to provide a hydrostatic gas bearing in which galling does not occur even when an overload occurs.

[0004]

SUMMARY OF THE INVENTION According to the present invention, there is provided a bearing portion opposed to an outer peripheral surface of a rotating shaft via a gap, and a plurality of ejection ports on an inner peripheral surface of the bearing portion. In a hydrostatic gas bearing for supporting a rotating shaft by a static pressure generated between a bearing portion and a rotating shaft generated by ejecting a gas, a bearing supporting portion opposed to an outer periphery of the bearing portion via an air gap, A pressure gas for generating a static pressure in a gap between the bearing portion and the bearing support portion is supplied to an ejection port provided to be opened on the inner peripheral surface of the portion, and to a discharge port provided in the bearing support portion. A contact hole between the ventilation hole and the bearing support portion and the bearing portion;
When the touch is detected, the drive source driving the rotary shaft is stopped.
And a contact detector .

[0005]

When the rotary shaft is driven to rotate, pressurized air is supplied from an air supply hole to float and support the bearing portion on the inner peripheral surface of the bearing support portion, and to place the rotary shaft on the inner peripheral surface of the bearing portion. Float and support. When an overload is applied to the rotating shaft and the rotating shaft comes into contact with the bearing portion, the bearing portion escapes into a gap between the bearing supporting portion and avoids contact between the rotating shaft and the bearing portion. Further, when a large load is applied such that the bearing section and the bearing support section come into contact with each other, the contact detector detects contact between the bearing support section and the bearing section, and the drive source that drives the rotating shaft is driven. Stop.

[0006]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
FIG. 1 is a side sectional view showing an embodiment of the present invention, in which a bearing support 2 having a cylindrical hollow portion is fixed inside a casing 1 having a cylindrical hollow portion. A cylindrical space is provided inside the bearing support 2, and the outer peripheral surface faces the inner peripheral surface of the bearing support 2 via a gap, and the inner peripheral surface faces the outer peripheral surface of the rotating shaft 3 via a gap. The opposing hollow cylindrical bearing 4 is housed through a gap. A concave portion is provided in the inner peripheral surface of the casing 1 to form an air reservoir groove 11 with the outer periphery of the bearing support portion 2, and a pressure air device (not shown) is provided through an air supply hole 12 opened to the outer periphery of the casing 1. Pressurized air is supplied to the air reservoir groove 11. The bearing support portion 2 includes a plurality of radially extending ventilation holes 21 and an axially extending ventilation hole 22 which are opened on the outer peripheral surface and the inner peripheral surface of the bearing support portion 2, penetrate the bearing support portion 2, and extend in the radial direction. It is provided. Vent 2
The injection ports 23, 24 are provided on the side of the bearings 1, 22 facing the bearing portion 4.
And pressurized air supplied from the air reservoir groove 11 is supplied to the jet port 23 and the axial jet port 2 on the inner peripheral surface of the bearing support 2.
4, the gas is ejected toward the outer peripheral surface of the bearing receiving portion 4 to float and support the bearing portion 4 in the radial direction and the axial direction. The bearing portion 4 is provided with an air reservoir 41 formed of a concentrically formed space, and the outer periphery thereof is provided with a projection 42 extending through the bearing support 2 and the casing 1. An open air supply hole 43 is provided to supply compressed air to the air reservoir 41 from a pressure air device (not shown). An ejection port 44 is provided on the inner peripheral surface of the bearing portion 4, and pressurized air is ejected from the air reservoir portion 41 through the ejection port 44 and between the bearing portion 4 and the rotary shaft 3.
The rotating shaft 3 is raised and supported. A contact detector 5 is provided between the bearing support 2 and the bearing 4 so that, when the bearing 2 and the bearing 4 come into contact with each other, the drive source driving the rotary shaft 3 is stopped. is there. Rotary axis 3
When rotating the bearing, pressurized air is supplied from the air supply holes 12 and 43 to float and support the bearing portion 4 on the inner peripheral surface of the bearing support portion 2 and to support the rotating shaft 3 on the inner periphery of the bearing portion 4. Float and support the surface. When an overload is applied to the rotating shaft 3 and contact occurs between the rotating shaft 3 and the bearing portion 4, the bearing portion 4 escapes into a gap between the bearing supporting portion 2 and the rotating shaft 3 and the bearing portion 4.
Avoid contact between Further, the bearing part 4 and the bearing support part 2
When a large load is applied so as to contact the shaft, the contact detector 5 detects the contact between the bearing support 2 and the bearing 4 and stops the drive source driving the rotating shaft 3.

[0007]

As described above, according to the present invention, even if an overload is applied to the rotating shaft, the bearing portion avoids contact with the rotating shaft and the bearing portion and the bearing supporting portion come into contact with each other. Since the rotating shaft is sometimes stopped, even if an overload occurs, no galling occurs and there is an effect that a safe static pressure gas bearing can be provided.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Casing 11 Air pool groove 12,43 Air supply hole 2 Bearing support part 21,22 Vent hole 23,24,44 Spout port 3 Rotary shaft 4 Bearing part 41 Air pool part 42 Projection part

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Shuji Ishii 12-1, Otemachi, Kokurakita-ku, Kitakyushu-shi, Fukuoka Prefecture Yasukawa Electric Co., Ltd. Kokura Plant (56) References JP-A-60-222617 (JP, A) JP-A-3-24319 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) F16C 32/06

Claims (1)

(57) [Claims] A bearing formed by providing a bearing portion facing an outer peripheral surface of a rotating shaft via a gap, and a plurality of ejection ports on an inner peripheral surface of the bearing portion, and ejecting a pressurized gas from the ejection port. A static pressure gas bearing that supports a rotating shaft by static pressure between a portion and a rotating shaft, wherein a bearing supporting portion opposing an outer periphery of the bearing portion via a gap, and an inner peripheral surface of the bearing supporting portion is opened. And a vent for supplying a pressurized gas for generating a static pressure in a gap between the bearing portion and the bearing support portion to the ejection port provided in the bearing support portion, and the bearing support portion And the bearing portion
And stops the drive source driving the rotary shaft.
And a contact detector for stopping the static pressure gas bearing.