JP2006084034A - Static pressure air bearing linear guide device - Google Patents

Abstract

An object of the present invention is to provide a static pressure air bearing linear guide device that suppresses a decrease in bearing performance with respect to a temperature change even when the stage is enlarged and is low in cost.
A pair of horizontal air bearings 6 is formed by providing a pair of facing portions 4 and 5 opposite to each other with a predetermined gap on both side surfaces of a guide member 2 protruding from a base 1. Vertical air bearings 7 that support the vertical direction are arranged outside the positions of the horizontal air bearings 6 in the width direction. In the vicinity of each of the vertical air bearings 7, suction force generating means 9 for sucking the stage 3 toward the base 1 in a non-contact state is provided.
[Selection] Figure 1

Description

  The present invention relates to a high-precision machining and hydrostatic air bearing linear guide device for moving a sample, tool, detector, etc., such as a measuring device, semiconductor manufacturing, and inspection device with high accuracy. The present invention relates to a static pressure air bearing linear guide device that is advantageous in this case.

A conventional static pressure air bearing linear guide device is generally arranged such that a movable body straddles a guide rail extending in the guiding direction from above, and when the stage 55 of the movable body is large, for example, FIG. A structure as shown is generally employed.
That is, a pair of guide rails 51 are provided with a predetermined distance in the width direction (horizontal direction orthogonal to the guide direction) with respect to the upper surface of the base 50, and opposed portions that face the outer surface and the lower surface of each guide rail 51. 52 are provided at both ends in the width direction of the lower portion of the stage 55, and the hydrostatic air bearings 53 that support the horizontal direction are disposed between the outer surface of the guide rail 51 and the facing portion 52, respectively. Static pressure air bearings 54 that support the vertical direction are arranged at the upper surface position and the lower surface position of each of the guide rails 51, which is an inner position in the width direction than the air bearing 53.

  However, in the apparatus configuration as shown in FIG. 3, for example, when a temperature difference occurs between the fixed body (base 50 and guide rail 51) and the movable body (stage 55 and facing portion 52), both are heated. Although a difference in expansion occurs, the pair of guide rails 51, that is, the pair of horizontal bearings 53 are separated in the width direction, so that the bearing clearance of each horizontal bearing 53 changes particularly, and in the worst case, the bearing clearance. The air bearing 53 in the horizontal direction may not be operated. This becomes more conspicuous as the width of the stage 55 becomes wider.

Further, since the two guide rails 51 are manually parallel and assembled to the base 50 at the time of assembly, it takes time and effort to produce the straightness in the horizontal direction, requiring assembly skills and time.
Furthermore, as described above, the size of the stage 55 is increased, and the thickness of the stage 55 is generally reduced in order to reduce the weight of the movable body. It is necessary to concentrate both the air bearings 53 and 54 that support the horizontal direction and the vertical direction at the side surface position, the upper surface and the lower surface position, and it is extremely difficult to improve the processing accuracy and the cost is high. The bearing clearance may not be obtained, resulting in a disadvantageous configuration in terms of bearing performance.
The present invention has been made paying attention to the above-mentioned problems, and provides a static pressure air bearing linear guide device that suppresses a decrease in bearing performance with respect to a temperature change and is low in cost even if the stage is enlarged. It is an issue.

In order to solve the above-mentioned problems, a static pressure air bearing linear guide device according to the present invention projects upward from a reference surface of a base and extends in the guide direction, and moves in the guide direction along the guide member. In a static pressure air bearing linear guide device having a movable body that is possible and an air bearing portion that supports and guides the movable body with air,
A horizontal direction in which a pair of facing portions facing each other with a predetermined gap on both side surfaces of the guide member is provided in the movable body, and a horizontal direction orthogonal to the guide direction is supported between the side surface of the guide member and the facing portion. Each air bearing is arranged, and a vertical air bearing that supports the vertical direction is arranged outside each horizontal air bearing position, and the movable body is in a non-contact state in the vicinity of each vertical air bearing. It is characterized by comprising a suction force generating means for sucking toward the base.

According to the present invention, the distance between the pair of horizontal air bearings is set to be small regardless of the size of the stage constituting the upper surface of the movable body, and the distance between the both side surfaces of the guide member and the distance between the pair of opposed portions. Since the amount of thermal expansion due to the temperature change is small, the amount of change in the bearing clearance is reduced, and stable bearing performance can be obtained.
Further, since the distance between the pair of horizontal air bearings is small, the moment rigidity is also large.

  In addition, since the vertical bearing is disposed outside the horizontal bearing in the width direction, the distance between the pair of vertical bearings can be increased in the width direction even if the distance between the pair of horizontal air bearings is reduced. Even if the stage is large, it can be supported horizontally, and for example, a vertical air bearing is placed near both ends in the width direction of the movable body, and it is strongly stable against moments such as an external load in the vertical direction. Straight line guidance.

Further, by providing suction force generating means in the vicinity of each vertical air bearing, the shear stress acting on the movable body due to the suction and floating of the movable body with respect to the base is set small.
Here, it is preferable that the guide member is disposed at a substantially central portion in the width direction of the stage. When arranged in this way, the horizontal air bearing supports the horizontal direction at a substantially central portion in the width direction of the stage, and the reaction force acting on the movable body from the horizontal air bearing becomes smaller.
In addition, the pair of vertical air bearings preferably have a mutual distance as large as possible, preferably symmetrically in the width direction.

By adopting the present invention, even if a temperature difference occurs between the fixed body and the movable body, there is almost no change in the bearing clearance in each air bearing without being affected by the size of the movable body. It has the effect of maintaining stable bearing performance.
In addition, since the straightness accuracy is determined by the machining accuracy without depending on human hands in both the vertical and horizontal directions, the production accuracy and stable assembly time can be reduced, and the cost can be reduced.
In addition, since the reaction force of the air bearing is hardly transmitted to the stage, the rigidity of the single stage is not required so much, and the plate thickness can be reduced, resulting in lighter weight and improved controllability.

Next, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a configuration diagram of the static pressure air bearing linear guide device of the present embodiment as viewed from the guide direction, and FIG. 2 is a side view of the device in which the adsorption force generating means is omitted.
First, the apparatus configuration will be described. The base 1 is provided with a horizontal reference surface 1a on the upper surface and extends in the guide direction, and a guide member 2 projects from a substantially central portion in the width direction of the upper surface of the base 1. The guide member 2 is a rail member having an angular cross section, and extends in the guide direction along the reference surface 1a. The guide member 2 has a total of three surfaces, a bottom surface and left and right side surfaces, which are straight and flat, and have a good parallel and right-angle accuracy.

The lower surface of the stage 3 that constitutes a part of the movable body with a predetermined interval above the reference surface 1a of the base 1 is disposed in parallel and facing.
Opposing portions 4 and 5 having opposing surfaces facing each other with a predetermined gap are provided on each side surface of the guide member 2 so as to sandwich the guide member 2 from the lower surface of the stage 3. An air hole that blows out air horizontally toward the side surface is provided on a surface of each of the facing portions 4 and 5 that faces the side surface, so that the space between each side surface of the guide member 2 and each of the facing portions 4 and 5 is provided. The horizontal air bearings 6 that respectively support the horizontal direction are formed.

In addition, an air hole that blows air downward is provided on the lower surface of the facing portion 5 on the outer side in the width direction of the facing portions 4 and 5, so that the lower surface of the facing portion 5 and the reference surface 1 a One vertical air bearing 7 is formed between them.
Further, a second opposing portion 8 projects downward from the lower surface of the movable body at a position symmetrical to the opposing portion 5 in the width direction, and other portions are provided between the lower surface of the second opposing portion 8 and the reference surface 1a. The vertical air bearing 7 is formed. As a result, each of the vertical air bearings 7 is disposed outward in the width direction with respect to each horizontal air bearing 6.

Here, as shown in FIG. 2, a plurality of the facing portions 4 and 5 and the second facing portion 8 are provided at a predetermined interval in the guide direction. In addition, the shape of the bearing portion of each air bearing is not limited to a circular shape, a rectangular shape, or other shapes.
Further, suction force generating means 9 is provided on the outer side in the width direction of each vertical air bearing 7.

Each suction force generating means 9 is provided on the upper surface of the base 1 and is made of a ferromagnetic material extending in parallel with the guide member 2, and is supported on the lower surface of the stage 3 so as to have a predetermined gap from the upper surface of the suction rail 9a. And a permanent magnet 9b opposed to each other. Reference numeral 9c denotes a spacer that supports the permanent magnet 9b, and is provided to facilitate the adjustment of the gap between the attracting rail 9a and the permanent magnet 9b, that is, the height position of the permanent magnet 9b.
Moreover, in FIG. 1, the code | symbol 10 represents the linear motor as an example of a drive device.

Next, the operation and the like of the static pressure air bearing linear guide device having the above configuration will be described.
In the apparatus having the above-described configuration, the stage 3 is floated and supported in the vertical direction with respect to the reference plane 1a by the pair of vertical air bearings 7 and the suction force generating means 9, and is paired with the pair of horizontal air bearings 6. Is positioned in the width direction. Then, it is driven by the linear motor 10 below the stage 3 and linearly moves along the guide member 2.

In this embodiment, the guide width by the guide member 2 can be narrowed regardless of the size of the stage 3, so that a so-called narrow guide state is achieved, whereby the distance of the horizontal air bearing 6 is narrow and the moment rigidity is strong. Become.
In addition, since the distance between the pair of horizontal air bearings 6 can be set small regardless of the size of the stage 3, even if a temperature difference occurs between the stage 3, the base 1 and the guide member 2, each horizontal direction The influence on the bearing clearance of the air bearing 6 is minimized, and stable bearing performance can be maintained against temperature changes.

Further, by providing the vertical air bearing 7 and the suction force generating means 9 that support and guide the vertical direction apart in the width direction, sufficiently stable vertical support is possible even if the stage 3 is enlarged.
At this time, the vertical air bearings 7 to be floated and the suction force generating means 9 to be sucked are arranged close to each other so that almost no shear stress due to the suction force and the lift force acts on the stage 3.

Further, the suction rail 9a is made of a ferromagnetic material, so that a suction force can be obtained with a small area and the weight can be reduced. Further, since the suction rail 9a extends in the direction parallel to the guide direction outside the vertical air bearing 7, the suction rail 9a prevents foreign dust and dirt from adhering to the vertical air bearing 7. Also has a role to do.
In addition, you may employ | adopt other magnetic means, such as an electromagnet, instead of the permanent magnet 9b. Further, as the suction force generation means 9, vacuum suction or other non-contact suction means may be employed.

Further, since the air bearings 6 and 7 and the suction force generating means 9 are each provided in the guide direction, even when the stage 3 becomes longer in the guide direction, the air bearings 6 and 7 and the suction force generator 9 are resistant to loads caused by the vertical and horizontal moments. ing. Moreover, by providing two apart in the guide direction, weight reduction can be achieved rather than making each opposing part 4,5,8 long in a guide direction.
Furthermore, since the above structure hardly causes stress due to the reaction force or suction force of the air bearings 6 and 7 on the stage 3, the thickness of the stage 3 can be reduced to the limit that can ensure the unit accuracy of the stage 3. For example, the stage 3 can be made of a material having a low longitudinal elastic modulus such as an aluminum alloy.

In the present embodiment, even when the air bearings 6 and 7 are not supplied with air, the stage 3 is attracted to the base 1 side and positioned by the magnetic force of the attractive force generating means 10.
In the above embodiment, the position of the pair of horizontal air bearings 6 is not symmetrical in the width direction because of the relationship with the arrangement of the linear motor 10, but the pair of horizontal air bearings 6 are left and right in the width direction as much as possible. It is preferable that it exists in a symmetrical position.

Moreover, in the said embodiment, although the up-down direction air bearing 7 is formed in the lower surface position of the opposing parts 8 and 5, it is not necessary to provide both the horizontal direction air bearing 6 and the up-down direction air bearing 7 in the opposing part 5. FIG. . You may provide the opposing part for an up-down direction air bearing separately.
Further, the suction force generating means 9 may be disposed inside the vertical air bearing 7, and the suction force generating means 9 and the vertical air bearing 7 do not need to be arranged in the width direction. That is, the suction force generating means 9 and the vertical air bearing 7 may be arranged side by side in a direction parallel to the guide direction. In this case, the vertical air bearing 7 is formed at the upper surface position of the suction rail 9a.

It is a block diagram seen from the guidance direction of the apparatus which concerns on embodiment of this invention. It is the schematic side view which abbreviate | omitted the attraction | suction force generation means which concerns on embodiment of this invention. It is a figure explaining the conventional apparatus structure.

Explanation of symbols

1 Base 1a Reference surface 2 Guide member 3 Stage (movable body)
4,5 Opposing part 6 Horizontal air bearing 7 Vertical air bearing 8 Second opposing part 9 Suction force generating means 10 Linear motor

Claims (1)

A guide member that protrudes upward from the reference surface of the base and extends in the guide direction, a movable body that can move in the guide direction along the guide member, and an air bearing portion that supports and guides the movable body with air. In a hydrostatic air bearing linear guide device having:
A horizontal direction in which a pair of facing portions facing each other with a predetermined gap on both side surfaces of the guide member is provided in the movable body, and a horizontal direction orthogonal to the guide direction is supported between the side surface of the guide member and the facing portion. Each air bearing is arranged, and a vertical air bearing that floats and supports in the vertical direction is arranged outside each horizontal air bearing position, and is movable in a non-contact state near each vertical air bearing. A static pressure air bearing linear guide device comprising suction force generating means for sucking a body toward a base.

Images