JPS6275125A - Magnetic composite type static pressure air bearing - Google Patents

Abstract

PURPOSE:To use a bearing in vacuum, make a movable body lightweight, and allow a high-speeed movement by providing a permanent magnet on a bearing pad and provided a magnetic fluid seal section on the outer peripher of a bearing face. CONSTITUTION:A permanent magnet 22 and a ring-shaped yoke 23 are integrally coupled with a pad main body 21 to form a bearing pad 2, and the main body 21 and the face of the yoke 23 facing a bearing guide 1 are aligned in the same plane to form a bearing face 20. The bearing face 20 is provided with an air blowout port 3 at its center and provided with discharge ports around the blowout port 3. A magnetic fluid seal section 24 is formed on the outer periphery of the bearing face 20 surrounding these blowout port 3 and discharge ports 4 to seal the outer periphery of the bearing gap via the magnetic suction force of the bearing pad 2 to the bearing guide 1.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to hydrostatic air bearings applied to precision measuring instruments, precision robots, precision processing machines, semiconductor manufacturing equipment, etc. Regarding type hydrostatic air bearings.

<Summary of the Invention> This invention provides a permanent magnet in the bearing pad and a magnetic fluid seal part on the outer periphery of the bearing surface, and in particular expands the range of use of hydrostatic air bearings, improves bearing rigidity by magnetic preload,
This prevents foreign matter from entering the bearing gap.

<Background of the Invention> Conventionally, in this type of static air bearing, as shown in FIG.
Pressure air is ejected into the gap between the bearing and the bearing, and the bearing load is supported by the film-like pressure air in the bearing gap. In such a static air bearing, the pressurized air between the bearings flows out to the outer circumference of the bearing, so if this bearing is installed in a device that is used in a vacuum, it may disturb conditions such as the degree of vacuum around the device and cause problems. This may cause problems such as delays. Furthermore, when the bearing is used under normal pressure, dust, dirt, etc. are kicked up by the airflow flowing out of the bearing, or they enter the bearing clearance, reducing bearing performance and equipment performance. Furthermore, in order to increase bearing rigidity in a self-floating type bearing, it is necessary to increase the dead weight load on the bearing portion, and increasing the dead weight causes a number of problems such as hindering the speeding up of the equipment.

<Objective of the Invention> An object of the present invention is to provide a novel magnetic composite type hydrostatic air bearing that can solve the above-mentioned conventional problems all at once with an extremely simple configuration.

<Structure and Effects of the Invention> In order to achieve the above object, the present invention incorporates a permanent magnet into the bearing pad, and arranges a magnetic fluid seal portion on the outer periphery of the bearing surface. According to the above configuration, in this invention, since a magnetic attraction force acts between the bearing pad and the bearing guide, the magnetic fluid seal part seals the outer periphery of the bearing clearance between the bearing surface and the bearing guide. Prevents pressure air from flowing out of the bearing. Therefore, it can be used as a bearing in a vacuum, and there is no dust or dust flying up or entering the bearing clearance, and the bearing performance is stabilized and improved. Moreover, due to the effect of the magnetic attraction force of the bearing pad on the bearing guide, it is possible to increase bearing rigidity for self-levitating type bearings without increasing the bearing's own weight, and by reducing the weight of the movable body and improving the resonance frequency, This has the effect of achieving the purpose of the invention with a simple configuration, such as realizing high-speed movement and positioning.

<Description of Embodiments> The drawings show an embodiment of a magnetic composite type hydrostatic air bearing according to the present invention.

The above-mentioned static pressure air bearing is composed of a bearing guide 1 made of a magnetic material and a bearing pad 2 disposed opposite to the bearing guide 1 with an arbitrary bearing gap therebetween.

The bearing pad 2 is circular as shown in FIG.

A permanent magnet 22 and a ring-shaped yoke 23 are integrally fitted into a bad body 21 having a rectangular or other arbitrary planar shape.1, the surfaces of the body 21 and the yoke 23 facing the bearing guide 1 are aligned on the same plane to form a bearing. A surface 20 is formed. The bearing surface 20 has an air outlet 3 such as an orifice throttle, a surface throttle, a porous throttle, etc. in the center thereof, and the air outlet 3.
An exhaust port 4 is provided around the jet port 3 and the exhaust port 4, and a magnetic fluid seal portion 24 is formed on the outer periphery of the bearing surface 20 surrounding the jet port 3 and the exhaust port 4.
The outer periphery of the bearing is sealed by the magnetic attraction force of the bearing.

The jet outlet 3 is connected to a pressure air source through an air guide hole 31 and an air supply pipe 32, and the exhaust port 4 is connected to the atmosphere or an air intake source through an air guide hole 41 and an air supply pipe 42, respectively.

FIG. 3 shows another embodiment of the bearing pad 2. In FIG.

In this embodiment, a permanent magnet 2 is attached to the bottom surface of the recess 26 of the yoke material 25, which has a cylindrical portion 27 surrounding the recess 26 having an opening on the lower surface.
2. The bearing pad 2 is constructed by integrally bonding the main body 21 to the lower surface of the permanent magnet 22, and the main body 21 and the cylindrical portion 27
A bearing surface 20 is formed by aligning the lower surfaces of the two to the same plane, and this bearing surface 20 has a pressurized air outlet 3 at the center, an exhaust port 4 at the periphery, and a magnetic fluid seal section 24 at the outer periphery, as in the previous example. is formed. In FIG. 4, the spout 3 is shown relative to the bearing surface 20.
An air pocket portion 28 is formed surrounding the air pocket portion 28, and the rest of the structure is the same as that of the embodiment shown in FIG. 3, so a description thereof will be omitted.

In the embodiment shown in FIG. 5, a bearing pad 2 is constructed by combining a yoke forming a main body 21 and a permanent magnet 22.
A disk-shaped permanent magnet 22 is on the lower surface of the yoke forming the main body 21, a ring-shaped permanent magnet 22a is on the outer periphery of the yoke, and this permanent magnet 2
A ring-shaped yoke 23 surrounding the outer periphery of the disk-shaped permanent magnet 22 is integrally connected to the lower surface of the disk-shaped permanent magnet 2a.
2 and the ring-shaped permanent magnet 22a are formed with N and S different magnetic poles on the upper and lower surfaces of each other, and the bearing surface 2
0 has a jet port 3 at the center, an exhaust port 4 around it, and a magnetic fluid seal section 24 at the outer periphery, as in each side.
has been set up.

The present invention is not limited to the above embodiments, and the number of permanent magnets 22 installed on the bearing pad 2 and the structure of the magnetic fluid seal portion 24 are not particularly limited, and may be set arbitrarily within the technical scope of the present invention. Of course.

Therefore, the pressurized air from the jet nozzle 3 forms an air film between the bearing surface 20 and the bearing guide 1 to form a predetermined bearing gap, and the bearing pad 2 floats with static pressure against the guide 1, and the pressurized air is exhausted to the atmosphere from the exhaust port 4.

On the other hand, between the bearing pad 2 and the bearing guide 1, as shown by the chain line, there is a space between the permanent magnet 22, the main body 21, and the bearing guide l.
, the magnetic flux that reaches the yoke 23 and the permanent magnet 22 flows, and as a result, the magnetic fluid seal portion 24 is held between the yoke 23 and the bearing guide 1 and seals the outer periphery of the bearing clearance, and also seals the outer periphery of the bearing gap. A magnetic attraction force acts between the bearing 1 and the bearing 1, and this functions to increase the bearing rigidity.

As described above, the present invention incorporates the permanent magnet 22 into the bearing pad 2 and arranges the magnetic fluid seal part 24 on the outer periphery of the bearing surface 20 to exert a magnetic attraction force between the bearing pad 2 and the bearing guide 1. As a result, the seal portion 24 seals the outer periphery of the bearing clearance and prevents pressure air from flowing out of the bearing. Therefore, it can be used as a bearing in a vacuum, and it also prevents dust and other particles from entering the bearing portion. This improves bearing performance.

Moreover, the rigidity of the bearing can be increased without increasing the weight of the bearing due to the action of the magnetic attraction force, thereby achieving the object of the invention by simplifying the structure, such as reducing the weight of the movable body and realizing high-speed movement.

[Brief explanation of drawings]

FIG. 1 is a vertical sectional view of a magnetic composite type hydrostatic air bearing according to the present invention, FIG. 2 is a bottom view of the bearing pad in FIG. 1, and FIGS. 3 to 5 are sectional views showing other embodiments. , FIG. 6 is a sectional view of a conventional example. 1... Bearing guide 2... Bearing pad 20.
... Bearing surface 21 ... Main body 22 ... Permanent magnet 23 ... Yoke 24 ... Magnetic fluid sealing part

Claims (2)

[Claims] (1) In a hydrostatic air bearing, pressurized air is ejected between the bearing guide and the bearing surface from the jet port of the bearing pad, and the bearing load is supported by the film-like compressed air in the bearing gap. 1. A magnetic composite hydrostatic air bearing characterized by having a magnetic fluid seal section disposed on the outer periphery of the bearing. (2) The magnetic compound hydrostatic air bearing according to claim 1, wherein the bearing pad has an exhaust port around the pressurized air outlet.