JPH0629084B2 - Floating support device - Google Patents

Description

The present invention relates to a floating support device for moving an article such as a semiconductor component in a clean environment, and more specifically, a spiral groove is formed on a rotary shaft of a motor or the like. The present invention relates to a floating support device that uses a support mechanism that is provided with a ceramics plate and is rotated to support an object with a fluid film generated by rotation of a spiral groove.

[Conventional technology]

Conventionally, it is the third moving device used to move articles in a clean environment such as semiconductor manufacturing or the biotechnology industry.
As shown in the figure, a large number of air nozzles 2 are formed on a floor surface 1 that conveys articles, and high-pressure air is supplied from under the floor 3 as shown by an arrow A, so that a levitation table 4 placed on the floor surface 1 is aired. Articles are transferred by a carrier box 5 mounted on a levitation table 4 which is pushed up by force and transferred. Here, a linear motor (secondary side) 6 is fixed to the levitation table 4,
Since the linear motor (primary side) 7 fixed to the floor sucks (repels) it, it can move to a predetermined position along the floor surface 1. Therefore, the air nozzles 2 are evenly arranged on the floor surface 1 over the entire length, but the valve seat 9 supported by the spring mechanism 8 is provided under the floor 3 so that the valve seat 9 can be brought into and out of contact with the upper surface of the valve seat 9. The valve 10 is formed at a position facing the air nozzle 2 of the above, and the permanent magnet 12 repels by the electromagnet 11 on the floor surface other than the portion where the levitation table 4 is passing, and the valve seat 9 is lifted, and the valve 10 is The air nozzle 2 is closed to reduce the consumption of high-pressure air so that the floating table 4
Can be opened and closed sequentially by moving.

Further, in FIGS. 4 and 5, the rail 1 attached to the base 17 is shown.
In another conventional example in which the movable table 15 can be moved on the carriage 3, the articles 16 can be transferred by the movable table 15 in which four legs 14 in total are movably mounted on the two parallel rails 13. it can.

In this case, the rails 13 are fixed at a predetermined interval.
Has a substantially trapezoidal cross-sectional shape, and both slopes 18
Guide grooves 19 for ball bearings are formed in
The ball bearing 21 fitted in this holds the movable table 15 via the leg 14.

Especially at the joint between the leg 14 and the rail 13, the rail 1
An oil groove 20 is formed in the guide groove 19 of No. 3, and a large number of ball bearings 21 are arranged inside the leg 14 along the guide groove 19 and the ball bearing 21
The grease can be supplied from the grease nipple 22 to the ball bearing 21. The ball bearing 21 is connected to the leg 14 by a piano wire (not shown) stretched in the oil groove 20.
It is designed so that it will not fall off even if it comes off the rail 13.

[Problems to be solved by the invention]

In the conventional supporting device using the air levitation method (see FIG. 3), the levitation table 4 and the floor surface 1 are not in solid contact with each other, so that the article can be conveyed without impact force and without vibration. However, in order to levitate the levitation table 4, air must be constantly ejected from the air nozzles 2 on the floor 1 facing the lower part of the levitation table 4, and the downward or horizontal air flow formed in the clean room. Will hinder the flow,
As a result, there is a problem that the articles are contaminated, and since the floating air itself must be highly purified, the operating cost is high.

In addition, the conventional linear guide system (Figs. 4 to 5) can be used for extremely large loads,
In addition, since NC can be accurately positioned,
Widely used for XY tables, optical mechanical measuring tables, etc., but if the rail length exceeds 3 m, it will be difficult to manufacture, so it was not suitable for transporting a long distance with large equipment. .

Further, when the ball bearing 21 is stationary or is moving at a low speed and receives an excessive load or impact load, the ball bearing 21 and the guide groove 19 are locally deformed permanently, and smooth after that. There was still a problem such as giving a big obstacle to the physical exercise.

Accordingly, the present invention seeks to eliminate these drawbacks of the prior art, and provides a means for transferring articles without using a large amount of air as in the air slider described above.
It is another object of the present invention to provide a floating support device, which has a simple structure and is capable of supporting a relatively large weight, and increasing the stability thereof to transfer the floating support, in an inexpensive form.

[Means for solving problems]

According to the present invention, a ceramic plate having a spiral groove is rotatably provided on a rotary shaft, and a pedestal having a flat surface whose surface facing the ceramic plate is smoothed is provided with a slight gap. In a floating support device, which is arranged so as to floatingly support the pedestal so as to generate a dynamic pressure of fluid between the ceramic plate and the pedestal that rotate by rotationally driving the rotating shaft, The floating support device is characterized in that a magnet is provided on the front surface or the back surface of the ceramic plate, and a ferromagnetic material is arranged on the flat surface side of the pedestal. In this case, a permanent magnet, an electromagnet, or both can be used as the magnet, and if a single magnetic pole is located on the flat side of the pedestal, a wide range of ferromagnetic materials can be used. . Therefore, in this floating support device, the ceramics plate is attracted to the flat surface of the pedestal by the magnetic force of the magnet, the parallelism between the flat surface and the ceramics plate surface is easily maintained, and a single magnetic pole is located on the flat surface side of the pedestal. By arranging such magnets, the change of the magnetic field with respect to the ferromagnetic material is small and stable support is possible.

〔Example〕

An embodiment of the present invention will be described with reference to FIGS. 1 and 2, and a supporting portion 23 fixes a disk-shaped ceramic plate 26 and a permanent magnet 27 to a tip portion of a drive shaft 31 of a motor 24 with a holding metal fitting 25. The motor 24 has legs 24 ₁ and a floor 1
It is fixed to. Surface 30 of the ceramic plate 26
2 has a spiral surface as shown in FIG. 2, and a spiral groove having a uniform depth of 3 to 50 μm is formed on a flat surface finished to have a waviness of 1 μm or less. In other words, in this spiral surface 30, the part not shown in the figure is a land 42, and the surface of the land 42 is finished to a smooth flat surface.
The waviness of the land 42 on the entire surface of the above is less than 1 μm. The blackened portions 43 and 44 are pressure equalizing grooves 44 that connect the spiral groove 43 and the ends of all the spiral grooves 43 on the inner peripheral side, respectively. In this embodiment, the spiral groove 43 and the pressure equalizing grooves 44 are Have the same groove depth.
As the ceramic plate 26 on which the spiral surface 30 is formed, SiC, Si ₃ N ₄ , Al ₂ O ₃ or the like can be used, but any ceramic having high strength and good thermal conductivity can be used.

As a method of processing the spiral surface 30, first, the surface of the disk-shaped ceramic plate 26 is lapped to have flatness such that the undulation of the entire surface is 1 μm or less, and the surface is mirror-finished. It is advisable to expose the pressure equalizing groove 44 only in the groove processing area, mask the other lands 42 with plastic or resin, and then perform shot blasting with alumina particles. If various factors such as the air pressure of shot blast and the particle size of alumina are changed, the depth of the groove also changes. However, in order to increase the dynamic pressure generated by the rotation of the spiral groove 43, this groove depth should be 3
It is preferably in the range of ˜50 μm.

Further, the fluid 40 interposed between the receiving surface 29 and the spiral surface 30 may be any of a compressive fluid such as air and carbon dioxide gas, a non-compressible fluid such as water oil, grease, and liquid metal. Further, even a magnetic fluid such as ultrafine particles dispersed in a high boiling point liquid can be used. In this case, when a fluid other than gas is used, it is considered to use a fluid-sealing structure or a supporting mechanism having a fluid circulation structure. Further, it is desirable that the receiving surface 29 is a smooth flat surface, but if the viscosity of the fluid 40 is high, a fluid film is formed even if the fluid 40 is not smooth, so the spiral surface 30 depends on the magnitude of the load applied to the spiral surface 30. Rotation speed and size, type of fluid 40 interposed on both sides, receiving surface 2
The smoothness of 9 and the material and the like of the member forming the receiving surface 29 will be appropriately selected. However, the receiving surface 29 cannot obtain a large dynamic pressure if the deviation from the ideal plane becomes large,
Hard ceramics with a small coefficient of thermal expansion, such as SiC and Si ₃ N ₄ , are desirable.

A plate-shaped permanent magnet 27 is provided on the back surface of the ceramic plate 26, and the side facing the ceramic plate 26 is magnetized to have the same magnetic poles.
Is fixed to the holding metal fitting 25. The rotation of the motor 24 is controlled by the arm 35 attached to the tip of the drive shaft 31.
It is transmitted to the ceramic plate 26 by rotating the pin 36 fixed to the back surface of the holding metal fitting 25. Also,
Since the pedestal 28 to which the receiving surface 29 is fixed is made of steel, the ceramic plate 2 is urged by the magnetic force of the permanent magnet 27.
The surface 30 of 6 is kept parallel to the receiving surface 29 with a slight clearance. Further, since the holding metal fitting 25 and the drive shaft 31 are spherical receiving surfaces 50, the receiving surface 29 and the motor 24
Even if the axis 31 'of the drive shaft 31 is displaced from the perpendicular positional relationship, the surface 30 of the ceramic plate 26 and the pedestal 28
The parallelism with the side receiving surface 29 is maintained by the permanent magnet 27, the rotation of the motor 24 is transmitted to the ceramic plate 26, and the thrust load from the side of the pedestal 28 is applied between the receiving surface 29 and the ceramic plate 26. It is supported by the power of the fluid 40 formed between it and the surface 30.

Therefore, the pedestal 28 (including the receiving surface 29) is supported without substantially contacting the rotating ceramic plate 26.

In FIG. 1, a pedestal 28 is a model of a moving platform for carrying an article on an upper portion (not shown), and the motor 2
Any of 4 can be used as long as it is of a known system.

Further, although the permanent magnet 27 is used as the magnet, any of electromagnets can be used. The permanent magnet 27 not only has a simple structure but also requires no maintenance. Further, in the case of an electromagnet, power is supplied by a slip ring or a brush, and there is an advantage that a strong magnetic force can be obtained.

In this embodiment, since the ceramic plate 26 having the spiral groove which is rotated by the motor is arranged so as to face the smooth receiving surface, the spiral groove 4 is formed by the rotation of the motor 24.
3 circulates the surrounding fluid into the center of rotation, and the ceramic plate 2 on which the receiving surface 29 and the spiral groove 43 are formed
A fluid film is formed between the spiral surface 30 of 6 and
The two planes can be sufficiently counteracted against the forces trying to bring them close together, so that the two planes can move relative to each other in a direction parallel to the receiving surface without touching each other. That is, if the pedestal 28 is formed on the bottom surface of the heavy object, the ceramic plate 26 having the spiral groove 43 provided below the pedestal 28 is attached to the motor 2.
If the receiving surface 29, which is the lower surface of the receiving table 28, is supported by the supporting mechanism configured to rotate at 4, the rotation of the ceramic plate 26 generates a dynamic pressure of the fluid interposed between the two flat surfaces. Therefore, the pedestal 28 is the ceramic plate 26.
Supported without touching up. The pedestal 28 can also move in parallel on the ceramic plate 26 in a floating state.

Therefore, when a plurality of the support mechanisms are provided on either side of the pedestal or the floor surface, the floating support device transfers the object without contact.

Also, in the present invention, the other side of the motor, that is,
Even in the sliding portion on the side not facing the pedestal 28, the load can be supported by using a dynamic pressure group bearing using a ceramic member in which a spiral groove is similarly formed. In this case, parallel movement is considered. Either of the spherical group bearing and the plane spiral group bearing can be applied because it is not necessary.In the latter case, a magnet is provided on the rotating side and the ferromagnetic member is fixed to the other for the same reason as above. By doing so, the stability can be improved.

〔The invention's effect〕

The present invention relates to a floating support device in which a ceramic plate having a spiral groove is rotated and a dynamic pressure is generated between the ceramic plate and a smooth flat surface facing the spiral groove so that the ceramic plate is rotated integrally with the ceramic plate. A magnet is fixed on the front surface or the back surface, and on the other hand, the surface of the ceramic on which the spiral group is formed by disposing the ferromagnetic material on the flat surface side of the pedestal is always opposed to the flat surface on the pedestal side by magnetic force. Since the parallel positional relationship is maintained, a fluid lubricating film is easily formed, and even if the ceramic plate and the pedestal are moved in parallel, the fluid lubricating film is similarly held and the ceramic is retained. The disk can support the pedestal in a stable state without substantially making direct contact, and increases the resistance of the fluid film even if the thrust load by the magnet increases. This is a small amount and does not cause any practical problems, and it is possible to impart a function capable of forming a stable fluid film by simply adding a simple structure to the floating support device applying the operating principle of the dynamic pressure group bearing. It is possible and practically useful.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view of an embodiment of the present invention, FIG. 2 is a front view of the ceramic seen from II in FIG. 1, and FIGS.
Each of the figures is an explanatory view showing a conventional example. 1: Floor surface, 2: Air nozzle, 3: Underfloor, 4: Levitation platform,
5: Carrier box, 6: Linear motor (secondary side),
7: linear motor (primary side), 8: spring mechanism, 9: valve seat, 10: valve, 11: electromagnet, 12: permanent magnet, 13:
Rail, 14: leg, 15: mobile platform, 16: article, 17:
Base, 18: slope, 19: guide groove, 20: oil groove, 21:
Ball bearing, 22: grease nipple, 23: support part, 24: motor, 24 ₁ ... leg, 25: holding metal fittings,
26: ceramic plate, 27: permanent magnet, 28: pedestal,
29: Receiving surface, 30: Spiral surface, 31: Drive shaft, 4
0: fluid, 50: spherical receiver.

Claims (3)

[Claims] 1. A ceramic plate having a spiral groove is rotatably provided on a rotary shaft, and a pedestal having a flat surface whose surface facing the ceramic plate is smoothed is provided with a slight gap. A floating support device for floatingly supporting the pedestal by generating a dynamic pressure of fluid between the ceramic plate and the pedestal that rotate by rotationally driving the rotating shaft. The floating support device according to claim 1, wherein a magnet is provided on the front surface or the back surface of the ceramic plate, and a ferromagnetic material is disposed on the flat surface side of the pedestal. 2. The floating support device according to claim 1, wherein the magnet is a permanent magnet. 3. The floating support device according to claim 1, wherein the magnet is an electromagnet.