JPH0251621A - Gas bearing spindle equipped with gas supply/exhaust mechanism - Google Patents

Abstract

PURPOSE:To make gas supply and vacuum exhaust possible to/from a rotary part without giving effects on rigidity of a gas bearing for a gas bearing spindle having a pair of thrust plates and a rotor fixed between them by providing a non-contact rotary joint at the thrust plate part. CONSTITUTION:Pressure gas supplied from a gas supply hole 21 jets to a small gap between a radial bearing 22 and a rotor 3 and a small gap between thrust bearings 23a, 23b and thrust plates 2a, 2b forming a gas film to support a rotary shaft 20 by static pressure. The gas pressure supplied to a gas supply passage 12 is transmitted to a gas supply groove 13, and because the gas supply groove 13 is sealed by a small gap of a non-contact seal 14, it is transmitted through gas supply passages 10b, 10c, 10a to an upper cylinder 8 of the rotary body 20. Gas leaked from the non-contact seal 14 is discharged from an exhaust hole 15 and a hole 6a. A rotary part can thus be rotated without friction so as to make gas supply possible while rotation, thereby gas supply to the rotary part can be achieved without giving effects on rigidity of a gas bearing.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a gas bearing that allows air supply and vacuum to pneumatic equipment on a rotating body during rotation.

[Prior art] Conventionally, this type of spindle was disclosed in Japanese Patent Application Laid-Open No. 62-218889.
It is stated in the number etc. In the conventional structure, a mechanism equivalent to a rotary joint was provided between the housing 101 of the static pressure gas bearing and the hollow shaft 102 (FIG. 3).

[Problems to be Solved by the Invention] However, in the conventional example described above, since the radial bearing portion 103 serves as a joint, there are the following drawbacks.

1) If the housing shape is the same, the bearing area will be smaller and the rigidity will be lower.

2) When air is supplied to the joint, the second air also wraps around the exhaust groove, increasing the pressure in the exhaust groove and reducing rigidity due to back pressure.

3) Processing of the housing becomes complicated.

[Means and effects for solving the problems] According to the present invention, by providing a non-contact rotating joint in the thrust plate section, air can be supplied to the rotating section and vacuum can be exhausted without affecting the rigidity of the gas bearing. It made it possible.

[Example] Fig. 1 is a drawing that best represents the features of the present invention, in which 1 is a housing of a hydrostatic gas bearing, 2a and 2b are disk-shaped thrust plates, and 3 is a cylindrical rotor. , the thrust plates 2a and 2b are attached to the rotor 3 with bolts etc.
The rotating body 20 is configured by being coupled to the rotating body 20. 22 is a cylindrical radial gas bearing, 23a and 23b are annular thrust gas bearings, 21 is an air supply hole, and the pressurized gas supplied from the air supply hole 21 is supplied to the small gap between the radial bearing 22 and the rotor 3. A gas film is blown out and formed in a minute gap between the thrust bearing 23a23b and the thrust plates 2a, 2b, thereby statically supporting the rotating shaft 20 in the radial direction and the thrust direction.

4 is a motor housing, 5 is a motor rotor, and 6 is a lid of the motor housing. 8 is a cylinder, 9 is an encoder, 11 is a coupling, and 17 is a flange for connecting with the coupling. 10a and 10b are air supply holes (passages) provided in the thrust plates 2a and 2b;
10c is an air supply hole (passage) provided in the rotor 3 of the gas bearing, 12 is an air supply hole (passage) provided in the motor housing 4, and 13 is an annular supply hole provided on the inner periphery of the motor housing 4. It is an air groove. 14 is thrust brake)-2
15 is a non-contact seal formed by a minute gap formed between b and the motor housing 4, and 15 is an exhaust hole. When air is supplied to the air supply passage 12, pressure is transmitted to the air supply groove 13. Air supply groove 1
3 is sealed by a minute gap of the non-contact seal 14, so the pressure is reduced to the air supply passage 10 of the thrust plate 2b.
b, Rotor 3 air supply passage 10C5 thrust plate 2
The air is transmitted to the cylinder 8 at the upper part of the rotating body 20 via the air supply passage 10a.

Since the non-contact seal 14 allows the rotating part to rotate without friction, air can be supplied even during rotation. Further, gas leaking from the non-contact seal 14 is exhausted from the exhaust hole 15 and the hole 6a of the lid 6 of the motor housing.

As described above, in the present invention, since no processing is performed on the bearing part, the bearing area can be maintained as before, and since it is not affected by air supply, air supply to the cylinder etc. is achieved while maintaining the rigidity as before. is possible.

In the above embodiment, a structure for supplying air to a cylinder or the like has been described, but when used for a vacuum chuck or the like, it may be connected to a vacuum pump or the like to form an exhaust structure.

Although the air supply port is provided in the motor housing 4 in FIG. 1, an air supply plate 16 may be attached as shown in FIG. In the example shown in FIG. 2, an air supply plate 16 is provided on the outer periphery of the upper thrust plate 2a, and air is supplied (or evacuated) only through an air supply passage 10a formed in the thrust plate 2a. , the operation and effect are similar to the embodiment shown in FIG.

[Effects of the invention] As explained above, by providing a non-contact seal on the thrust plate instead of on the radial bearing surface, the rotating body can be supplied with air or vacuumed without affecting the bearing surface, that is, without reducing the rigidity. Exhaust can be carried out.

In addition, even when air supply and exhaust are not required, it can be used as a normal air bearing of the same size, and no machining is required on the housing, just adding holes on the thrust plate and rotor. The structure is simple and can be manufactured at low cost.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of an air spindle with a motor according to an embodiment of the present invention, Fig. 2 is a sectional view of a main part of another embodiment of the invention, and Fig. 3 is a sectional view of a conventional gas bearing structure. be. 1: Housing, 2a, 2b nislast plate, 3: Rotor 10a, 10b, 10c, 12: Air supply passage, 13: Air supply groove, 14: Non-contact seal, 15: Exhaust hole, 20: Rotating body.

Claims (5)

[Claims] (1) A rotating body is constituted by a pair of thrust plates and a rotor fixedly provided between the pair of thrust plates, a housing is provided between both thrust plates on the outer periphery of the rotor, and the housing and the thrust plate are provided. and a static pressure gas bearing that forms a small gap for static pressure support between the rotor and the rotor, which forms an air supply passage passing through the inside of the rotary body, and forms a gas supply passage around the rotary body at the entrance of the air supply passage. An air supply member is provided, an annular air supply groove is provided in the air supply member facing the entrance of the air supply passage, and a non-contact seal structure is created between the air supply member and the rotating body. A gas bearing spindle with a supply/exhaust mechanism. (2) The gas bearing spindle with an air supply/exhaust mechanism according to claim 1, further comprising a leakage means that connects the minute gap of the non-contact seal structure to the outside. (3) The air supply passage has an inlet on the outer peripheral surface of one thrust plate, passes through the central rotor, passes through the other thrust plate, and has an outlet on the outer surface of the other thrust plate. A gas bearing spindle with an air supply/exhaust mechanism according to claim 2. (4) The air supply passage has an inlet on the outer peripheral surface of one of the thrust plates, passes through the inside of the thrust plate, and has an outlet on the outer surface of the thrust plate. Gas bearing spindle with air supply and exhaust mechanism as described. (5) In a gas bearing in which the rotating part consists of a thrust plate and a rotor, a hole is provided that opens from one thrust plate to the outer periphery of the other thrust plate, and the outer periphery of the other thrust plate is connected through a small gap. A gas bearing spindle with an air supply/exhaust mechanism, characterized in that a surrounding member is provided, an annular groove is provided at a position facing the opening, and a hole is provided that communicates the groove with the outside.