JP2014024663A - Levitation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a levitation device which is increased in load-carrying capacity and can be thereby used as a levitation device for levitating a workpiece having a shape other than a light-weight and thin-plate shape, a non-rigid workpiece, a large-weight workpiece, or the like.SOLUTION: According to the present invention, a levitation device 1 forms an air film between a support surface and a workpiece surface and thereby levitates a workpiece above the support surface. The levitation device includes: a porous carbon pad 2 which is formed of a porous material, and on the surface of which the support surface is formed; an air-impermeable pad holder 4 which accommodates the porous carbon pad; a plurality of grooves 10 which are formed between the porous carbon pad and the pad holder; and a high-pressure gas flow passage 14 which is formed in the pad holder and communicates with the grooves. Each of the plurality of grooves constitutes a space independent of the other grooves. In each of the plurality of grooves, an opening 12 which communicates with the high-pressure gas flow passage is formed.

Description

  The present invention relates to a levitation device, and more particularly, relates to a levitation device capable of forming an air film between a support surface and a surface of a workpiece, levitation of the workpiece on the support surface, and movement of the workpiece without contact. .

  A levitation device is known in which high-pressure air is allowed to flow out of a support surface to form an air film between the support surface and the surface of the workpiece, and the workpiece is floated on the support surface. An example of such a levitation device is a levitation device using a porous carbon pad as described in Patent Document 1.

JP 2008-7319 A

The floating device of Patent Document 1 has been used for floating (that is, supporting) a flat and relatively light workpiece such as a thin glass substrate or a semiconductor wafer used in a liquid crystal display device.
Such a conventional levitation device is used for levitation of a relatively lightweight workpiece. A gas having a pressure of less than 1 MPa is introduced into the device, and the gas is formed of a porous body. The workpiece is allowed to flow out (blow out) from the surface (support surface) of the pad, and the work is floated on the support surface.

Since such an apparatus has an excellent characteristic that it can support a workpiece in a non-contact manner, it is used in a liquid crystal display device as described above by increasing the load capacity (increasing the load capacity). It is expected to be used to float (support) a workpiece other than a flat and relatively light workpiece such as a thin glass substrate or a semiconductor wafer.
The load capacity refers to an index indicating a load that can be supported by the levitation device.

  Here, in order to increase the load capacity of the levitation device, it is necessary to increase the pressure of the gas supplied to the levitation device. For example, when a gas having a high pressure of 1 MPa or more is introduced to increase the capacity, problems such as internal damage and inability to withstand long-term use have occurred.

  For this reason, the conventional levitating apparatus using the porous body as disclosed in the cited document 1 and the like has a high load capacity, a workpiece having a shape other than a lightweight thin plate shape, a non-rigid workpiece, a relatively heavy weight However, it could not be used as a levitation device for levitating large workpieces.

  The present invention has been made in order to solve such problems, and by increasing the load capacity, the floating of a workpiece having a shape other than a lightweight thin plate shape, a non-rigid workpiece, a workpiece having a large weight, etc. An object is to provide a levitation device that can be used as a device.

  As a result of repeated studies to solve the above problems, the inventors of the present invention have found that the width of the groove formed on the surface of the holder supporting the porous carbon pad (carbon pad) is When the high-pressure gas is introduced into the groove, the porous carbon pad may be peeled off near the corner or intersection of the groove. Based on this finding, the present invention has been made.

According to the present invention,
A levitation device that forms an air film between a support surface and a surface of a workpiece and levitates the workpiece on the support surface,
A porous carbon pad formed of a porous body, the surface of which is the support surface;
A non-breathable pad holder that houses the porous carbon pad;
A plurality of grooves formed between the porous carbon pad and the pad holder;
A high-pressure gas flow path formed in the pad holder and communicated with the groove;
Each of the plurality of grooves constitutes a space independent of the other grooves,
Each of the plurality of grooves is formed with an opening communicating with the high-pressure gas flow path.
A levitation device is provided.

  According to such a configuration, even if a high-pressure gas of 1 MPa or more is introduced into the groove formed between the porous carbon pad and the pad holder, damage is unlikely to occur, and the high load capacity of the levitation device can be increased. It becomes possible.

According to another preferred embodiment of the invention,
Each of the plurality of grooves is a linear groove.

According to the other preferable aspect of this invention The said opening is formed in the longitudinal direction center of each said groove | channel.

According to another preferred embodiment of the invention,
The plurality of grooves are annular grooves arranged concentrically.

According to another preferred embodiment of the invention,
The pressure of the high-pressure gas supplied to the plurality of grooves is 1 MPa or more.

  According to the present invention, there is provided a levitation device that can be used as a levitation device that levitates a workpiece having a shape other than a light thin plate shape, a non-rigid workpiece, a workpiece having a large weight, and the like by increasing the load capacity.

It is a top view of the levitation device of a preferred embodiment of the present invention. It is sectional drawing along the II-II line of FIG. It is a top view of the pad holder of the levitating apparatus of the 2nd Embodiment of this invention. It is a top view of the pad holder of the levitation device of other embodiments of the present invention.

  Hereinafter, a levitation device according to a preferred embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a plan view of a levitation apparatus 1 according to a preferred embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along line II-II in FIG.

  The levitation device 1 of the present embodiment is a levitation device that levitates a workpiece having a shape other than a lightweight thin plate shape, a workpiece that is not a rigid body, a workpiece having a large weight, and the like.

  The levitation device 1 includes a rectangular carbon pad 2 made of porous carbon and a non-breathable metal pad holder 4 in which the carbon pad 2 is accommodated. On the upper surface of the pad holder 4, a rising portion 6 is formed along the outer peripheral edge, and a recess surrounded by the rising portion 6 is a housing portion 8 in which the carbon pad 2 is housed.

  The carbon pad 2 is formed of a carbon material (porous carbon) having a higher degree of bond strength and superior bending strength than the carbon material (porous carbon) of the carbon pad used in the conventional levitation device, Can withstand high pressure.

Specifically, the carbon material (porous carbon) of the carbon pad used in the levitation device of the prior art is a binary system using filler and binder, the Shore hardness is HSD 65, and the air permeability is 0. The bending strength was about 35 N / mm ² at ² to 6.0 cm ² / sec.
On the other hand, the carbon material (porous carbon) of the carbon pad 2 used in the levitation apparatus 1 of this embodiment is a one-component system, the Shore hardness is HSD 100 to 125, and the air permeability is 0.2 to 6.0. (Cm ² / sec) and bending strength is 64 to 108 N / mm ² .

  As described above, the air permeability of the carbon pad 2 is substantially equal to the air permeability of the carbon pad used in the conventional levitation apparatus, but the hardness, bending strength, etc. are higher than the conventional values. It has become.

It is important not to change the air permeability when adjusting the material to produce the carbon bud.
In the levitation device, before the flow of the supplied high-pressure gas flows out into the support gap between the supported body and the carbon pad, the flow of the high-pressure gas supplied to the carbon pad is reduced by the throttling function of the carbon pad. It is adjusted properly.
Therefore, the characteristics of the levitation device are determined by the restriction of the carbon pad. When the air permeability changes, the characteristics of the restriction change and the support characteristics also change. Therefore, in this embodiment, the material is adjusted so that the air permeability does not differ from the material of the carbon pad of the prior art.

  On the other hand, in the levitation device of this embodiment, the porous or carbon having higher hardness and bending strength than the conventional carbon material so that it is not easily damaged even when it comes into contact with the support, and the additional capacity is increased. Used as a pad material.

Here, the air permeability K is expressed by the following formula 1.
K = Q · L / P · A Equation 1
Q: Aeration rate (MPa · cm ³ / sec)
L: Carbon pad 2 thickness (cm)
P: Pressure in groove 10 (MPa)
A: Area of the groove 10 facing the carbon pad 2 (cm ² )

  Further, the rising portion 6 of the pad holder 4 is configured such that the height is slightly lower than the thickness of the carbon pad 2. Therefore, when the carbon pad 2 is accommodated in the accommodating portion 8 of the pad holder 4, the upper surface of the carbon pad 2 is placed above the top surface of the rising portion 6 of the pad holder 4.

  A plurality of linear elongated grooves 10 are formed on the bottom surface of the housing portion 8 surrounded by the rising portion 6. The grooves 10 are arranged in parallel so as not to communicate with each other, are independent from each other, and have a constant width.

  When the carbon pad 2 is accommodated in the accommodating portion 8 and fixed in the accommodating portion 8 by an adhesive or the like, each groove 10 is closed from above by the back surface of the carbon pad 2 and becomes an independent space.

  One opening 12 is formed in the center of each groove 10 in the longitudinal direction, and each opening 12 is a high-pressure gas disposed outside the levitation device 1 via a high-pressure gas flow path 14 formed in the pad holder 4. Communicating with a source (not shown).

  In the levitation apparatus 1 having such a configuration, a high-pressure gas of 1 MPa or more is supplied into each groove 10 from a high-pressure gas supply source via a high-pressure gas flow path 14. Since each groove 10 is closed from above by the carbon pad 2 made of porous carbon, the high-pressure gas passes through the pores in the carbon pad 2 and is substantially uniform from the entire surface 2a (support surface) of the carbon pad 2. To leak.

  When the work is arranged above the support surface 2a in this state, the high-pressure air that flows out substantially uniformly from the entire surface (support surface) of the carbon pad 2 forms an air film between the support surface and the work. It is supported above the support surface of the carbon pad 2 of the levitation device 1.

Next, the levitation device 20 according to the second embodiment of the present invention will be described. FIG. 3 is a plan view of the pad holder 22 of the levitation device 20.
The levitation device 2 has the same structure as the levitation device except that the planar shape is circular and the plurality of grooves 24 formed in the pad holder 22 are annular grooves arranged concentrically. .

  In the levitation device 20, each annular groove 24 is independent, and one opening 26 is formed in each annular groove 24. The openings 26 are arranged in a line in the radial direction, and the openings 26 are arranged at a high pressure gas supply source (not shown) disposed outside the levitation device 20 through a high pressure gas flow path formed in the pad holder 22. ).

  Even in the levitation apparatus 20 having such a configuration, a high pressure gas of 1 MPa or more is supplied into each groove 24 from a high pressure gas supply source through a high pressure gas flow path. Since each groove 24 is closed from above by a disk-like carbon pad made of porous carbon, the high-pressure gas passes through the pores in the carbon pad and is substantially uniform from the entire surface (support surface) of the carbon pad 2. To leak.

  When the work is placed above the support surface in this state, the high-pressure air ejected substantially uniformly from the entire surface (support surface) of the carbon pad forms an air film between the support surface and the work, and the work is levitated. It is supported above the support surface of the 20 carbon pads.

  Without being limited to the above-described embodiment of the present invention, various changes and modifications can be made within the scope of the technical idea described in the claims.

  The levitation apparatus of the above embodiment has a configuration in which one opening is opened in one groove formed in the pad holder, but the present invention has a plurality of openings in one groove. Configuration, for example, as shown in FIG. 4, a configuration in which two openings 34, 34 are formed in one groove 32 of the pad holder 30, or three or more openings are formed in one groove. It may be configured.

1: Floating device 2: Carbon pad 4: Pad holder 6: Rising part 8: Housing part 10: Groove 12: Opening 14: High-pressure gas flow path

Claims (5)

A levitation device that forms an air film between a support surface and a surface of a workpiece and levitates the workpiece on the support surface,
A porous carbon pad formed of a porous body, the surface of which is the support surface;
A non-breathable pad holder that houses the porous carbon pad;
A plurality of grooves formed between the porous carbon pad and the pad holder;
A high-pressure gas flow path formed in the pad holder and communicated with the groove;
Each of the plurality of grooves constitutes a space independent of the other grooves,
Each of the plurality of grooves is formed with an opening communicating with the high-pressure gas flow path.
A levitation device characterized by Each of the plurality of grooves is a linear groove.
The levitation device according to claim 1. The opening is formed in the longitudinal center of each groove,
The levitation device according to claim 2. The plurality of grooves are annular grooves arranged concentrically.
The levitation device according to claim 1. The pressure of the high pressure gas supplied to the plurality of grooves is 1 MPa or more;
The levitation device according to any one of claims 1 to 4.

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