JP4346067B2 - Precision table - Google Patents

Description

  The present invention relates to a precision table capable of moving a sample, a tool, a detector and the like with high positioning accuracy in a high-precision processing apparatus and measurement apparatus, a semiconductor manufacturing or inspection apparatus, and the like.

  A conventional static pressure gas bearing linear guide device generally includes a guide rail extending in the guide direction, a movable body arranged so as to straddle the upper side of the guide rail, and movable in the guide direction, and the movable body. And an air bearing portion supported and guided by gas.

  An example of such a static pressure gas bearing linear guide device is shown in FIG. As shown in FIG. 11, a pair of guide rails 51 is provided as a guide portion 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 the outer side surfaces of the respective guide rails 51 And an air bearing that supports the horizontal direction between the outer surface of the guide rail 51 and the facing portion 52 by providing facing portions 52 facing the lower surface at both ends in the width direction of the lower portion of the table 55 that is a movable body. In addition to the arrangement of the portions 53, the air bearing portions 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 that are inward in the width direction of the horizontal air bearing portion 53. (For example, refer to Patent Document 1).

Further, as a modification of the above-described static pressure gas bearing linear guide device, there is one in which one guide rail is provided as a guide portion along the guide direction.
JP 2000-120684 A (see FIG. 5)

  In recent years, if the static pressure gas bearing linear guide device is enlarged with the conventional structure in order to cope with the increase in the size and the stroke of the movable body, the guide rail becomes longer in proportion to the size of the guide rail. May not be maintained. Also, it is very difficult to manufacture such a long guide rail.

  For example, when a long guide rail is made of ceramics, there is no possibility of firing because there is no large firing furnace. In addition, even if there is a large firing furnace, there is a problem that the yield is deteriorated and the processing becomes difficult.

Moreover, in the base which supports a guide member, there exist the following problems depending on the material.
1) In the case of a stone base When the base is made of stone, a general stone does not have a large Young's modulus, so it is necessary to increase the thickness dimension to prevent deflection. For this reason, there is a problem that the mass increases and the manufacturing and transport costs increase.
Furthermore, when the base is made of stone, it has a problem of load resistance at the place of installation, and the feasibility is poor.
Further, in the case of removing a rib structure, for example, an unnecessary portion, for reducing the weight of the base, there is a problem that the material is stone and the workability is poor and the cost is high. In addition, the wall thickness cannot be reduced very much due to the problem of breakage and it is difficult to reduce the weight.

2) Case of casting base When the base is made of cast metal, the specific gravity is large, but it is possible to reduce the weight by making a thick rib structure. From the standpoint of maintaining accuracy, it is a big problem.
In addition, for example, the glass substrate is becoming larger in size year by year, and accordingly, the apparatus is not suitable as a base material for use in an exposure apparatus intended for a substrate such as a liquid crystal display, which is inevitable to enlarge the apparatus. .

3) In the case of ceramic base When the base is made of ceramic, the size of the integral firing from the die cost at firing, the physical size of the kiln to be fired, and the technical aspect of firing (cracking problem) There is a problem that there is a restriction on

  The present invention has been made to solve such problems of the prior art, and even if a guide member having a minimum necessary length is used, the movable body can be increased in size and lengthened. An object is to provide a precision table that can be realized.

According to a first aspect of the present invention for achieving the above object, there is provided at least one guide member provided on a base and extending in a guide direction, and a guide direction along the guide member via a conveying means. And a gas bearing means for supporting and guiding the movable body with gas, wherein the guide members are arranged to be added at predetermined intervals along the guide direction. together comprising a plurality of guide portions, the build-up portion facing the gas bearing means of the guide portion is subjected to a concave shape, to name a concave shape crowned shape of該継adding portion, continuous with the crowning profile When the maximum depth of the guide portion from the plane portion facing the gas bearing means is the crowning length L, the length L is set to 1 to 2 μm .

According to a second aspect of the present invention, there is provided at least one guide member provided on the base and extending in the guide direction, a movable body movable along the guide member in the guide direction via a conveying unit, And a gas bearing means for supporting and guiding the movable body with gas, wherein the guide member is composed of a plurality of guide portions that are arranged at predetermined intervals along the guide direction. In addition, the additional portion of the guide portion facing the gas bearing means has a concave shape, the concave shape of the additional portion has a crowning shape, and the guide portions to be extended are provided on the base. A precision table is characterized in that it is straightened by a reference block and fixed by a wedge-shaped guide presser in order to prevent displacement in the horizontal direction .

According to a third invention, in the first invention or the second invention, when the number of the guide members is two or more, the extension portions are in the same position facing each other, and the crowning shapes are substantially the same. It is in a precision table that features

  According to the present invention, since the guide member is added, it is possible to produce by applying the conventional technology without using a large firing furnace, and the extended portion is added with high accuracy. Therefore, a highly accurate precision table can be provided.

  Further, according to the present invention, since the bases are added and configured, and the bases are combined by bolt fastening, for example, even when manufacturing with ceramics, it is possible to manufacture by applying the conventional technology.

  Hereinafter, although one Example of this invention is described based on figures, this invention is not limited to this.

FIG. 1 is a schematic plan view showing the structure of the precision table of the present embodiment, FIG. 2 is a schematic side view thereof, FIG. 3 is a detailed view of an added portion (A part), FIG. 4 is a detailed view of a crowning shape, and FIG. FIG. 5 is a cross-sectional view taken along arrow V-V in FIG. 1.
As shown in FIG. 1 to FIG. 5, the precision table according to the present embodiment is provided on a base 11 and has at least one guide member 12 extending in the guide direction, along the guide member 12. A precision table provided with a movable body (table) 14 movable in the guiding direction via the conveying means 13 and a static pressure gas bearing means 15 for supporting and guiding the movable body 14 with gas, The guide member 12 is composed of a plurality of guide portions 12-1, 12-2, 12-3,... 12-n that are added and arranged at predetermined intervals along the guide direction. The extension part 16 facing the gas bearing means 15 is formed with a concave shape.

Enlargement of the extension portion 16 is shown in FIGS.
As shown in these drawings, the guide portions 12-3 and 12-4 are in contact with each other and extended, and the shape facing the gas bearing means 15 of the extension portion 16 is a concave shape and contacts. I'm trying not to get it.
Specifically, as shown in FIG. 4, the concave shape has a crowning inclination length CL of about 5 to 15% of the moving direction of the gas bearing means 15, preferably about 10%. It is good to do. The crowning length L is 5 μm or less, preferably 1 to 2 μm. In practice, it is desirable to determine the balance between the bearing clearance to be set and the rigidity.

  When straightness accuracy is required, it is desirable that the two crowning shapes of the joint portions 16 between the parallel guide portions are matched as much as possible.

  In this way, the joint portion 16 between the guide portions has a minute crowning shape as shown in FIG. 4 so as not to have a convex portion, so that it contacts the gas bearing means 15 when the movable body 14 moves. To prevent movement and smooth movement.

As an extension method, as shown in FIG. 3, it is easy to add the reference block 20 in advance and straighten (parallelly) the running direction using another linear guide. A wedge-shaped guide retainer 21 is used for fixing the guide portion and preventing horizontal displacement.
By such an addition method, the straightness of the guide portion can be obtained easily and with high accuracy. However, even if this method is used, if no crowning is provided in the joint portion of the guide portion, it is surprisingly difficult to prevent any step in the width direction at the joint portion between the guide portions. Therefore, by performing crowning of appropriate sizes CL and L, problems due to the occurrence of such a step are eliminated.

In the present embodiment, the gas bearing means 15 includes two horizontal air bearing portions 15A arranged in a linear direction on the back surface side of the movable body 14 with a predetermined distance from one guide member 12, and a vertical ( For example, a linear motor 13 serving as a conveying means disposed at the center of the base 11 is supported by being levitated and supported in the vertical and horizontal directions with respect to the guide member 12. Thus, linear motion is enabled with respect to the guide member 12.
The horizontal air bearing portion 15A faces the inner surface of the guide member 12, and is arranged in parallel with a predetermined gap with respect to the inner surface.
And the air hole (illustration omitted) which blows off air toward the inner surface of the guide member 12 is formed in the surface facing the inner surface of the guide member 12. By blowing air from the air holes to the inner surface of the guide member 12, a horizontal air bearing is formed between the air holes and the guide member 12, and the movable body 14 is supported horizontally with respect to the guide member 12. The
As an air bearing system, various types such as a porous throttle and an orifice throttle can be used.
The vertical air bearing portion 15B faces the surface of the guide member 12, and is arranged in parallel with a predetermined gap with respect to the surface.
An air hole (not shown) that blows air toward the surface of the guide member 12 is formed on the surface facing the surface of the guide member 12. By blowing air from the air holes to the surface of the guide member 12, a vertical (up and down) direction air bearing is formed between the air hole and the guide member 12, and the movable body 14 moves vertically with respect to the guide member 12. Supported.
Further, the pressure of the air blown out from each air hole can be the same or different between the horizontal air bearing portion 15A and the vertical (vertical) air bearing portion 15B, and is set independently. You can also. Thus, if it sets independently, even if a change arises in the arbitrary clearance gaps between bearing part 15A, 15B and the guide member 12 by deformation | transformation of the movable body 14, for example, the air supply pressure of air according to the change It is preferable because fine adjustment can be performed by adjusting.
In the present embodiment, the number is two, but when straightness or posture system is required, it is more desirable to use a plurality of three or more in order to ensure stable running.

  Thereby, it becomes possible to easily realize a high precision large precision table.

6 is a schematic plan view showing the structure of the precision table of this embodiment, FIG. 7 is a schematic side view thereof, FIG. 8 is a cross-sectional view taken along arrow VIII-VIII in FIG. 6, and FIG. FIG. 10 is an enlarged view of a portion B in FIG. 9.
In addition, about the same member as the structure shown in FIG. 1, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

  As shown in FIGS. 6 to 10, the precision table according to this embodiment is provided on a base 11, and extends along the guide member at least one guide member 12 extending in the guide direction. A precision table comprising a movable body 14 movable in a guiding direction via a conveying means 13 and a static pressure gas bearing means 15 for supporting and guiding the movable body with a gas, wherein the base 11 is And a plurality of base parts 11-1, 11-2, and 11-3 that are added and arranged at predetermined intervals along the guide direction, and the base parts are fastened through fastening means 31. Is.

  Moreover, as shown in FIG. 9, it is preferable that the said base parts 11-1, 11-2, and 11-3 are made into a rib structure, and the material is made from ceramics.

In the present embodiment, in the addition part of the plurality of base parts 11-1, 11-2, 11-3, the side parts of the adjacent base parts are fastened by fastening means 31 such as bolts, After the fastening, for example, finishing is performed.
As this finishing process, for example, a grinding finish or a lapping finish may be applied.

Further, the bottom surface of the base 11 serves as a support portion of the gantry 40 and is installed, for example, via a support plate 41 so as not to cause a step.
Further, adjustment means such as a leveling bolt 42 is provided on the gantry 40 side so that the installation height with respect to the installation surface can be adjusted.

Further, on the upper surface of the base 11, two rails as guide members 12 are arranged at a predetermined interval as a guide surface of the gas bearing means 15.
In addition, a linear motor as the conveying means 13 is arranged in the center portion to enable linear guidance.

  As described above, since the base is made of ceramic and a plurality of members are joined with accuracy, a large table with high accuracy can be easily realized. As a result, a large high-precision table using ceramics can be realized at a low weight and at a low cost.

In addition, the first embodiment and the second embodiment are combined so that the guide portion and the base are both composed of a plurality of members, and the high precision accuracy table is constructed by connecting them with high accuracy. It may be.
In addition, the linear motor is used as the conveying means. However, the present invention is not limited to this, and various types such as a combination of a motor and a feed screw (for example, a ball screw), a combination of a motor, a plurality of pulleys, and a transmission belt may be used. it can.

Hereinafter, the weight reduction and the cost reduction due to the difference in the material of the base will be described.
1) In the case of a stone base If it is assumed that the size is W1000 mm × L3000 mm × t300 mm and the specific gravity is 3, it will be about 2700 kg.
2)
In the case of a ceramic base, assuming that the size is W1000 mm × L3000 mm × t150 mm and the specific gravity is 3.5, it is about 1575 kg.
Even if it is made of ceramics and does not have a rib structure, the weight can be reduced by about 42%.

FIG. 2 is a schematic plan view showing the structure of a precision table according to the first embodiment. FIG. Detail drawing of an addition part (A part). Detailed view of crowning shape. VV arrow sectional drawing of FIG. FIG. 6 is a schematic plan view showing the structure of a precision table according to the second embodiment. FIG. VIII-VIII arrow sectional drawing of FIG. IX-IX arrow sectional drawing of FIG. The B section enlarged view of FIG. Schematic of the precision table concerning a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Base 12 Guide member 13 Conveying means 14 Movable body 15 Gas bearing means 16 Additional part 20 Reference block 21 Guide presser 31 Fastening means 40 Mounting stand

Claims (3)

At least one guide member provided on the base and extending in the guide direction, a movable body movable in the guide direction along the guide member via the conveying means, and the movable body by gas A precision table provided with gas bearing means for supporting and guiding,
The guide member includes a plurality of guide portions that are extended and arranged at a predetermined interval along the guide direction, and an extension portion that faces the gas bearing means of the guide portion is formed with a concave shape. adding part of the concave shape to name a crowning shape, when the maximum depth from the plane portion facing the gas bearing means of the guide portion contiguous with the crowning profile and the length L of the crowning, said length L is A precision table set to 1 to 2 μm . At least one guide member provided on the base and extending in the guide direction, a movable body movable in the guide direction along the guide member via the conveying means, and the movable body by gas A precision table provided with gas bearing means for supporting and guiding,
The guide member includes a plurality of guide portions that are extended and arranged at a predetermined interval along the guide direction, and an extension portion that faces the gas bearing means of the guide portion is formed with a concave shape. The concave shape of the added portion forms a crowning shape, and the guide portions to be joined are straightly joined by a reference block provided on the base and are wedge-shaped to prevent horizontal displacement. A precision table that is fixed by a guide press. 3. The precision table according to claim 1, wherein there are two or more guide members, the extension portions are in the same position facing each other, and the crowning shapes are substantially the same.

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