HK1194792A - Aerostatic bearing and linear guide employing said aerostatic bearing - Google Patents

Description

Hydrostatic gas bearing and linear guide device using the same

Technical Field

The present invention relates to a static pressure gas bearing and a linear motion guide device using the same.

Background

In precision machine tools, semiconductor exposure apparatuses, and the like, it is required to position a workpiece such as a processing tool or a substrate with high accuracy. For this purpose, a linear motion guide device is used in which a static pressure gas bearing is mounted with little friction with a positioning device of a table for a workpiece. In such a linear guide device, a lubricant film of compressed air is provided between a movable table as a table for a workpiece and a guide rail as a guide member so that the movable table moves in a non-contact manner with respect to the guide rail.

As a throttle form of an air blow hole used for a static pressure gas bearing of the linear guide device, there are a porous throttle, a surface throttle, a small hole throttle, a self-throttling, and the like, and the static pressure gas bearing having the above throttle form can be used while adjusting a load capacity, a bearing rigidity, and the like according to different uses.

For example, patent document 1 describes that a graphite carbon-based material having a substantially uniform particle diameter and having open pores of uniform uniformity is used as a bearing member in a hydrostatic bearing pad fixed to either a supported body or a support body, and the support body is supported so as to be movable by pressurized air supplied to the bearing surface through the bearing member.

Further, patent document 2 proposes a gas bearing device capable of maintaining high rigidity and realizing high damping performance, the gas bearing device including two substantially parallel bearing surfaces facing each other and at least one gas passage for supplying gas to a bearing gap between the two bearing surfaces through a small hole.

Further, in patent document 3, a static pressure gas bearing is proposed, which includes: a base material composed of a porous body; and a surface orifice layer joined to the base material and formed of a porous plate manufactured by adjusting the diameter and distribution of through holes in advance in order to achieve a desired air throughput.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open No. 63-231020

Patent document 2: japanese patent laid-open publication No. 2006-510856

Patent document 3: japanese patent laid-open No. 2001-

Patent document 4: japanese patent laid-open No. 2008-82449

The above-described conventional hydrostatic gas bearing, although capable of realizing ultra-low friction, ultra-high precision and ultra-high speed operation, has the following problems: high-strength metal and ceramics are mainly used as bearing materials, and it is necessary to perform high-precision polishing and finishing of the bearing surface formed of the bearing material, which inevitably causes a problem of high cost.

However, in applications where the above-described ultra-low friction, ultra-high precision, and ultra-high speed operation are not required, for example, in which an article such as a liquid crystal panel is conveyed without contact or the article is moved horizontally without causing a temperature change, although there is an advantage that the structure of the apparatus is simplified when the hydrostatic gas bearing is used, on the other hand, the hydrostatic gas bearing itself is expensive, and thus the hydrostatic gas bearing cannot be widely used in the above-described applications, which is also a practical case.

In view of the above-described circumstances, in order to provide an inexpensive hydrostatic gas bearing that can be applied in various fields, the present applicant has first proposed a hydrostatic gas bearing that integrally includes: a synthetic resin bearing member having a plurality of air outlet ports each having a shape of a choke hole or a small-bore choke hole on an upper surface thereof, and an air supply groove communicating with the plurality of air outlet ports on a lower surface thereof; and a bearing base body joined to a lower surface of the bearing member so as to cover the air supply groove, and having an air supply port communicating with the air supply groove (patent document 4).

According to the static pressure gas bearing described in patent document 4, the synthetic resin bearing member constituting the static pressure gas bearing can be formed by injection molding using a mold, and machining is not required, and the structure of the bearing base body is also only required to form the gas supply port communicating with the bearing body, and the static pressure gas bearing can be assembled by joining the bearing body and the bearing base body, and mass production of the static pressure gas bearing can be performed, and the static pressure gas bearing can be provided at low cost.

However, since the air outlet port in the static pressure gas bearing described in patent document 4 is formed by injection molding using a die, and has a relatively large diameter of about 0.2 to 0.4mm, such as a self-orifice or a small hole, there is a possibility that the amount of supplied air blown out from the air outlet port is too large to cause self-excited vibration, and improvement is still required in practical use.

Disclosure of Invention

The present invention has been made in view of the above circumstances, and an object thereof is to provide a static pressure gas bearing which can be mass-produced and is inexpensive, and a linear motion guide device using the static pressure gas bearing.

The hydrostatic gas bearing of the present invention is characterized by comprising: a synthetic resin-made bearing body having an annular recess formed in one surface of the bearing body, an annular shoulder surface connected to an outer peripheral wall surface of the annular recess and having a larger diameter than the outer peripheral wall surface, an annular groove opened in the other surface of the bearing body, and a plurality of air blowing holes (japanese patent No. り) opened in the annular groove at one end and opened in an annular bottom surface of the annular recess at the other end; an annular seal member mounted in contact with the annular shoulder surface; and a bearing body having an air supply passage on one surface facing one surface of the bearing body, the air supply passage being open at one end to the one surface of the bearing body facing the one surface of the bearing body and being open at the other end to an outer peripheral surface of the bearing body, the bearing body being integrated with the bearing body by having an opening of the annular recess communicating with the air supply passage of the bearing body and being fastened and fixed to the bearing body by a plurality of fastening members, the annular groove having a width of at least 0.3mm and a depth of at least 0.01mm, the air blow-out hole having a diameter of at least 30 μm at one end thereof, and a self-restricting hole being formed between the annular recess and the annular groove.

According to the static pressure gas bearing of the present invention, the bearing body made of synthetic resin is fastened and fixed to the bearing base body via the annular seal member attached in contact with the annular shoulder surface, therefore, the synthetic resin bearing body and the bearing base body are firmly integrated with high sealing performance, and the synthetic resin bearing body is provided with an annular groove which is opened on the other surface and a plurality of air blowing holes which are opened on one end of the annular groove and opened on the annular bottom surface of the annular concave part on the other end, the annular groove has a width of at least 0.3mm and a depth of at least 0.01mm, the air blowing holes have a diameter of at least 30 μm on one end, since the self-throttling hole is formed between the annular recessed portion and the annular groove, the annular groove and the plurality of air blow holes can be formed without machining, and therefore, mass production can be performed, and manufacturing can be performed at low cost.

In a preferred embodiment, the annular groove has a width of 0.3 to 1.0mm or 0.3 to 0.7mm, a depth of 0.01 to 0.05mm or 0.01 to 0.03mm, and the air blowing hole has a diameter of 30 to 120 μm at one end thereof.

Preferably, the annular groove and the air blowing hole are formed by laser processing. The processing laser light can be selected from a carbon dioxide laser, a YAG laser, a UV laser, an excimer laser, and the like.

The annular groove and the air blow hole are formed by laser processing, and can be formed instantaneously as compared with machining such as cutting, and can be mass-produced and manufactured at low cost.

In the static pressure gas bearing according to the present invention, the inner peripheral wall surface of the annular recess may be formed as a truncated conical surface gradually expanding from the opening portion toward the annular bottom surface.

In the static pressure gas bearing of the present invention, the ball pressure receiving recess may be formed in the other surface of the bearing base.

In the static pressure gas bearing of the present invention, the ball pressure receiving recessed portion may have a truncated cone recessed portion or a concave spherical portion opened on the other surface of the bearing base body, and these ball pressure receiving recessed portions may be formed directly on the other surface of the bearing body.

In the static pressure gas bearing according to the present invention, the ball pressure receiving recessed portion includes a cylindrical recessed portion having an opening portion on the other surface of the bearing base, and the block is fittably fixed to the cylindrical recessed portion, and the block has a truncated conical recessed portion on one surface, and the truncated conical recessed portion is opened to the opening portion of the cylindrical recessed portion.

In the static pressure gas bearing according to the present invention, the ball pressure receiving recessed portion includes a cylindrical recessed portion having an opening portion on the other surface of the bearing base, and the block is fittably fixed to the cylindrical recessed portion, and the block has a concave spherical surface portion on one surface, and the concave spherical surface portion is opened to the opening portion of the cylindrical recessed portion.

In the static pressure gas bearing having the ball pressure receiving recessed portion on the other surface of the bearing base, the ball of the ball pin is disposed in sliding contact with the ball pressure receiving recessed portion, for example, and in this case, the static pressure gas bearing has a function of self-aligning around the ball.

The hydrostatic gas bearing with the automatic centering function is suitable for a linear guide device used as a positioning device of a loading table of a workpiece.

In the static pressure gas bearing of the present invention, the bearing body may further include, in addition to the annular groove: a large-diameter annular groove formed on one surface of the bearing body and surrounding the annular groove on an outer side thereof; a plurality of first radial grooves, one end of each of which opens into the annular groove, and the other end of each of which opens into the large-diameter annular groove; a small-diameter annular groove formed inside the annular groove; and a plurality of second radial grooves, one end of each of which opens into the annular groove, and the other end of each of which opens into the small-diameter annular groove.

The linear guide device including a hydrostatic gas bearing according to the present invention may be configured such that a movable table having an upper plate opposed to the upper guide surface and a pair of side plates opposed to the both side guide surfaces is disposed outside a guide member having the upper guide surface and the both side guide surfaces as the guide surfaces, ball pins are provided so as to stand on a lower surface of the upper plate of the movable table and inner surfaces of the pair of side plates respectively so that balls face inward, and the hydrostatic gas bearing is disposed between the ball pins and the upper surface and both side surfaces of the guide member so that ball pressure receiving recesses are brought into sliding contact with the balls of the ball pins, and a bearing body is opposed to the upper guide surface and both side guide surfaces of the guide member.

According to the linear guide device of the present invention, since the compressed air is jetted from the plurality of air blowing holes of the bearing body toward the guide surface of the guide member, the movable table can be kept in a non-contact state with respect to the guide surface by the air lubrication film formed between the guide surfaces. Further, if the bearing gap (about several μm to several tens μm) between the bearing body and the guide surface is not uniform, a pressure difference occurs in each part of the bearing gap, and the bearing body can be automatically centered in a direction in which the bearing gap is uniform due to the pressure difference, so that the state of being parallel to the guide surface can be maintained. Therefore, the accuracy of the components such as the parallelism and squareness of the guide member and the movable table can be set to a high accuracy, and the cost of the hydrostatic gas bearing itself can be reduced and an inexpensive linear guide device can be provided.

In the static pressure gas bearing of the present invention, the bearing body is preferably formed of a thermoplastic synthetic resin such as a polyacetal resin, a polyamide resin, or a polyphenylene sulfide resin, and the bearing base body is preferably formed of a thermoplastic synthetic resin such as a polyacetal resin, a polyamide resin, or a polyphenylene sulfide resin, or a thermoplastic synthetic resin containing a reinforcing filler in which 30 to 50 mass% of a glass fiber, a glass powder, a carbon fiber, or an inorganic filler is contained in the thermoplastic synthetic resin, or aluminum or an aluminum alloy. These synthetic resin bearing body and bearing base can be formed by machining a synthetic resin material or by injection molding using a mold.

According to the present invention, it is possible to provide a low-cost static pressure gas bearing which can be mass-produced and a linear motion guide device using the static pressure gas bearing.

Drawings

Fig. 1 is a top explanatory view of a preferred example of the embodiment of the present invention.

Fig. 2 is a sectional view of the line II-II of fig. 1.

Fig. 3 is a bottom explanatory view of fig. 2.

Fig. 4 is a bottom explanatory view of the bearing body of fig. 2.

Fig. 5 is a partially enlarged sectional explanatory view of fig. 2.

Fig. 6 is a bottom explanatory view of the bearing base.

Fig. 7 is a view of a VII-VII line of fig. 6 in cross-section.

Fig. 8 is a bottom explanatory view of the bearing body.

Fig. 9 is an explanatory view of the IX-IX line of fig. 8 in a sectional view.

Fig. 10 is a perspective explanatory view of fig. 8.

Fig. 11 is a cross-sectional explanatory view of an assembly of the bearing base body and the bearing body.

Fig. 12 is a top explanatory view of another embodiment of the bearing body.

Fig. 13 is a bottom explanatory view of another embodiment of the bearing base.

Fig. 14 is a sectional view of the line XIV-XIV of fig. 13.

Fig. 15 is a sectional explanatory view of an assembly of the bearing base body and the bearing body shown in fig. 14.

Fig. 16 is a sectional explanatory view of a hydrostatic gas bearing having a self-aligning function.

Fig. 17 is a bottom explanatory view of another embodiment of the bearing base.

Fig. 18 is a sectional view of the line XVIII-XVIII of fig. 17.

Fig. 19 is a sectional explanatory view of an assembly of the bearing base body and the bearing body shown in fig. 18.

Fig. 20 is a sectional explanatory view of a hydrostatic gas bearing having a self-aligning function.

Fig. 21 is a bottom explanatory view of another embodiment of the bearing base.

Fig. 22 is a sectional view showing the line XXII to XXII of fig. 21.

Fig. 23 is a perspective explanatory view of fig. 21.

Fig. 24 is a sectional explanatory view of the block.

Fig. 25 is a sectional explanatory view of a bearing base to which the block shown in fig. 21 is fitted and fixed.

Fig. 26 is a sectional explanatory view of an assembly of the bearing base body and the bearing body shown in fig. 25.

Fig. 27 is a sectional explanatory view of a hydrostatic gas bearing having a self-aligning function.

Fig. 28 is a sectional explanatory view of another embodiment of the block.

Fig. 29 is a sectional explanatory view of a bearing base to which the block shown in fig. 28 is fitted and fixed.

Fig. 30 is a cross-sectional explanatory view of an assembly of the bearing base body and the bearing body shown in fig. 29.

Fig. 31 is a sectional explanatory view of a hydrostatic gas bearing having an automatic aligning function.

Fig. 32 is a cross-sectional explanatory view of the linear guide device using the hydrostatic gas bearing.

(symbol description)

1 static pressure gas bearing

2 bearing base body

3 annular seal member

4 screwing component

5 bearing body

13 gas supply passage

22 annular recess

23 outer peripheral wall surface

24 annular shoulder surface

31 air blowout hole

Detailed Description

Next, the present invention will be described in further detail based on examples of preferred embodiments shown in the drawings. The present invention is not limited to these examples.

In fig. 1 to 5, a hydrostatic gas bearing 1 includes: a bearing substrate 2, the bearing substrate 2 preferably being made of a thermoplastic synthetic resin such as polyacetal resin (POM), polyamide resin (PA), polyphenylene sulfide resin (PPS), or a thermoplastic synthetic resin containing a reinforcing filler, which contains 30 to 50 mass% of glass fiber, glass powder, carbon fiber, or an inorganic filler in the thermoplastic synthetic resin, or aluminum or an aluminum alloy; and a bearing body 5 made of synthetic resin, wherein the bearing body 5 is screwed by the screwing member 4 to be integrated with the bearing base body 2 via the annular seal member 3, and is preferably formed of a thermoplastic synthetic resin such as polyacetal resin, polyamide resin, polyphenylene sulfide resin, or the like.

As shown particularly in fig. 6 and 7, the bearing base 2 includes: an air supply hole 9, the air supply hole 9 having a circular opening 8 at one end 6, the opening being open to one circular surface 7 in plan view; an air supply passage 13, the air supply passage 13 communicating with the air supply hole 9 at one end 10 and opening to the outer peripheral surface 12 at the other end 11; and a plurality of bolt insertion holes 18, each bolt insertion hole 18 being opened at one end 14 to one surface 7 and at the other end 15 to the other surface 17 while being enlarged in diameter by the annular stepped portion 16, the plurality of bolt insertion holes 18 being formed at equal intervals in the circumferential direction.

A female screw 20 is formed at an end 19 of the outer peripheral surface 12 that opens into the air supply passage 13, and an air supply plug (not shown) is screwed and fixed to the female screw 20.

As shown particularly in fig. 8 to 10, the bearing body 5 includes: an annular recess 22 formed on a surface 21 that is circular in plan view on the side opposite to the one surface 7 of the bearing base 2; an enlarged diameter recess 25 formed by the annular shoulder surface 24 and opening on one surface 21; an annular groove 27 that opens to the other circular surface 26 in plan view; a plurality of air blowing holes 31 which communicate with the annular groove 27 at one end 28 and open to the annular bottom surface 30 of the annular recess 22 at the other end 29; and a plurality of female screw holes 32 formed at equal intervals in the circumferential direction on the outer peripheral edge of the one surface 21.

The annular shoulder surface 24 has: a radial annular shoulder surface 24a connected to the cylindrical outer peripheral wall surface 23 of the annular recess 22 and extending radially outward; and an axially cylindrical shoulder surface 24b connected to the radial annular shoulder surface 24a and extending in the axial direction.

As shown in fig. 5, the annular groove 27 formed by the annular surface 33 of the bearing body 5 and the cylindrical surface 34 opposed to each other has a width W of at least 0.3mm and a depth D of at least 0.01mm, and in this example, the air blowing hole 31 has a diameter D of at least 30 μm from one end 28 to the other end 29 thereof, and a self-restricting hole is formed between the annular bottom surface 30 of the annular recess 22 and the annular groove 27.

As shown in fig. 8 to 10, the inner peripheral wall surface 35 of the annular recess 22 is formed as a frustoconical surface 37 extending gradually from the opening 36 of the annular recess 22 to the annular bottom surface 30 of the annular recess 22, and by forming the inner peripheral wall surface 35 as the frustoconical surface 37, the annular thin-walled portion 38 formed between the annular bottom surface 30 of the annular recess 22 and the one surface 21 is not increased in the radial direction, and the volume of the annular recess 22 can be increased, so that the strength of the bearing body 5 having the annular thin-walled portion 38 is not reduced.

The annular recess 22 is formed by an annular bottom surface 30 on which the other end 29 of the air blowing hole 31 is opened, a cylindrical outer peripheral wall surface 23 connected to the outer edge of the annular bottom surface 30, and an inner peripheral wall surface 35 having a frustoconical surface 37 connected to the inner edge of the annular bottom surface 30.

In particular, as shown in fig. 2, an o-ring as the annular seal member 3 is attached to the enlarged diameter recess 25 of the bearing body 5 so as to protrude from the opening 36 of the annular recess 22 with a crushing amount, and is pressed against and sandwiched between the one surface 21 of the bearing body 5 and the one surface 7 of the bearing base 2, thereby sealing between the surfaces 21 and 7.

According to the above-described hydrostatic gas bearing 1, the bearing body 5 is screwed and integrated with the bearing base body 2 via the o-ring attached to the diameter-enlarged concave portion 25 by the hexagon socket bolt as the screwing member 4, and therefore, inexpensive manufacturing can be realized. Further, the air outlet holes 31 are extremely small in diameter D of at least 30 μm, and the generation of self-excited vibration due to ejection of a large amount of air from the air outlet holes 31 can be suppressed.

Next, an example of a method of manufacturing the static pressure gas bearing 1 shown in fig. 1 to 5 will be described, in which first, a bearing body 2 made of synthetic resin or made of aluminum or aluminum alloy containing a reinforcing filler shown in fig. 6 and 7 and a bearing body 5a having no annular recessed groove 27 and air blow-out hole 31 in the bearing body 5 made of synthetic resin shown in fig. 8 to 10 are prepared, as shown in fig. 11, an opening 36 of an annular recessed portion 22 of the bearing body 5a is made to communicate with an opening 8 of an air supply hole 9 of the bearing body 2 via an o-ring attached to an enlarged diameter recessed portion 25, a female screw hole 32 of the bearing body 5a is made to align with one end 14 of a bolt insertion hole 18 of the bearing body 2, then a hexagon socket bolt as a tightening member 4 is inserted through the bolt insertion hole 18, and a male screw portion of the hexagon socket bolt is screwed into the female screw hole 32 of the bearing body 5, the bearing base body 2 and the bearing body 5 are screwed and integrated to form an assembly 39.

The other surface 26 of the bearing body 5a of the assembled body 39 screwed and integrated as described above is irradiated with a laser beam by a laser processing machine to form an annular groove 27 and a plurality of air blowing holes 31 each having a shape of a throttle hole, wherein the annular groove 27 has a width W of 0.3 to 1.0mm and a depth D of 0.01 to 0.05mm, and the air blowing holes 31 are opened from the annular surface 33 of the annular groove 27 to the annular bottom surface 30 of the annular recess 22 through the bearing body 5a from the annular surface 33, and have a diameter D of at least 30 μm, preferably 30 to 120 μm.

The processing laser used may be selected from a carbon dioxide laser, a YAG laser, a UV laser, an excimer laser, and the like, and a carbon dioxide laser is preferably used.

A carbon dioxide laser having a laser output of 9.5W was used to perform single-pass imprint at a scanning speed of 1000mm/s for a processing time of 2 seconds, so that an annular groove 27 having a width of 0.5mm and a depth of 0.05mm centered on a circular arc having a diameter of 30mm was formed and processed on a surface 26 of a bearing body 5 made of polyphenylene sulfide resin, and 10 air blow holes 31 each having a self-orifice shape were formed in an annular surface 33 of the annular groove 27 at 10 equi-divisional positions in the circumferential direction at a laser output of 14W and a processing time of 15 seconds, and the air blow holes 31 penetrated through the bearing body 5 from the annular surface 33 and opened to an annular bottom surface 30 of an annular recess 22, and having a diameter of 0.06 mm.

The bearing body 5 of the static pressure gas bearing 1 has one annular groove 27, but the bearing body 5 may have, in addition to the annular groove 27, a large-diameter annular groove 40, a plurality of radial grooves 43, a small-diameter annular groove 44, and a plurality of radial grooves 47 as shown in fig. 12, wherein the annular groove 40 is formed on one surface 26 of the bearing body 5, surrounds the annular groove 27 on the outer side of the annular groove 27, and is concentric with the annular groove 27, one end 41 of the radial groove 43 opens into the annular groove 27, the other end 42 opens into the large-diameter annular groove 40, the small-diameter annular groove 44 is formed on the inner side of the annular groove 27, and is concentric with the annular groove 27, one end 45 of the radial groove 47 opens into the annular groove 27, and the other end 46 opens into the small-diameter annular groove 44.

In the static pressure gas bearing 1 having the bearing body 5 shown in fig. 12, the air supplied to the annular recessed groove 27 is supplied to the large-diameter annular recessed groove 40 and the small-diameter annular recessed groove 44 via the radial recessed grooves 43 and 47, and therefore, the supply area becomes large, and stable floating can be performed, for example, when an article floats.

Fig. 13 to 16 show another embodiment of the hydrostatic gas bearing 1, in which a concave portion 49 having an opening 48 which is circular in a plan view is formed in a central portion of the other plane 17 which is circular in a plan view of the bearing base 2, and the concave portion 49 has a bottom surface 50 which is circular in a plan view and a frustoconical surface 51 which extends from the bottom surface 50 toward the opening 48 so as to gradually expand.

Similarly to the above-described static pressure gas bearing 1, the bearing body 2 having the concave portion 49 is configured such that the opening portion 8 of the air supply hole 9 communicates with the opening portion 36 of the annular concave portion 22 of the bearing body 5 having the o-ring mounted in the enlarged diameter concave portion 25, and the female screw hole 32 of the bearing body 5 is aligned with the one end 14 of the bolt insertion hole 18 of the bearing body 2, and then the bearing body 2 and the bearing body 5 are screwed and integrated by inserting the hexagon socket bolt as the fastening member 4 through the bolt insertion hole 18 and screwing the male screw portion of the hexagon socket bolt into the female screw hole 32 of the bearing body 5, thereby forming the assembly 52.

The other surface 26 of the bearing body 5 of the assembled body 52 screwed and integrated as described above is irradiated with a laser beam by a laser processing machine to form an annular groove 27 and a plurality of air blowing holes 31 each having a shape of a throttling hole, wherein the annular groove 27 has a width W of 0.3 to 1.0mm and a depth D of 0.01 to 0.05mm, and the air blowing holes 31 are formed in the annular surface 33 of the annular groove 27 so as to penetrate the bearing body 5 from the annular surface 33 and open to the annular bottom surface 30 of the annular recess 22, and have a diameter D of at least 30 μm, preferably 30 to 120 μm.

In the hydrostatic gas bearing 1 formed as described above, as shown in fig. 16, the ball 54 of the ball pin 53 is disposed in sliding contact with the frustoconical surface 51 of the recess 49 of the bearing base 2, and thus has a self-aligning function.

Fig. 17 and 20 show another embodiment of the static pressure gas bearing 1, in which a concave portion 49 having an opening 48 in a circular shape in a plan view is formed in a central portion of the other surface 17 in the circular shape in a plan view of the bearing base 2, and the concave portion 49 has a concave spherical surface 55, and the concave spherical surface 55 is expanded from the bottom surface 50 toward the opening 48.

Similarly to the above-described static pressure gas bearing 1, the bearing body 2 including the concave portion 49 having the concave spherical surface 55 is configured such that the opening portion 8 of the air supply hole 9 is communicated with the opening portion 36 of the annular concave portion 22 of the bearing body 5 having the o-ring mounted in the diameter-enlarged concave portion 25, and the female screw hole 32 of the bearing body 5 is aligned with the one end 14 of the bolt insertion hole 18 of the bearing body 2, and then the socket head cap bolt as the fastening member 4 is inserted through the bolt insertion hole 18, and the male screw portion of the socket head cap bolt is screwed and fixed to the female screw hole 32 of the bearing body 5, so that the bearing body 2 and the bearing body 5 are fastened and integrated, thereby forming the assembly 56.

In the same manner as described above, the other surface 26 of the bearing body 5 in the assembled body 56 screwed and integrated as described above is irradiated with a laser beam by a laser processing machine to form the annular recessed groove 27 having a width W of 0.3 to 1.0mm and a depth D of 0.01 to 0.05mm and the plurality of air blowing holes 31 having a shape of a throttle hole, and the air blowing holes 25 are formed in the annular surface 33 forming the annular recessed groove 27, penetrate the bearing body 5 from the annular surface 33, are opened to the annular bottom surface 30 of the annular recess 22, and have a diameter D of at least 30 μm, preferably 30 to 120 μm.

In the hydrostatic gas bearing 1 formed as described above, as shown in fig. 20, the ball 54 of the ball pin 53 is disposed in sliding contact with the concave spherical surface 55 of the concave portion 49 of the bearing base 2, and thus has a self-aligning function.

Fig. 21 to 27 show another embodiment of the hydrostatic gas bearing 1 having the self-aligning function. A cylindrical recess 59 having an opening 57 which is circular in a plan view and a circular bottom surface 58 is formed in a central portion of the other plane 17 which is circular in a plan view of the bearing base 2, and as shown in fig. 24, a block 68 is fitted and fixed to the cylindrical recess 59 with one plane 62 facing the bottom surface 58 of the cylindrical recess 59, wherein the block 68 includes: a cylindrical body 60; a circular hole 63 having one end 61 opened to one surface 62 of the cylindrical body 60; and a recess 67 connected to the other end 64 of the circular hole 63, extending gradually expanding from the other end 64 toward the other surface 65, and having a frustoconical surface 66 opening on the other surface 65 of the cylindrical body 60.

Similarly to the above-described static pressure gas bearing 1, the bearing body 2 to which the block 68 is fitted and fixed is configured such that the opening 8 of the air supply hole 9 communicates with the opening 36 of the annular recess 22 of the bearing body 5 to which the o-ring is attached in the enlarged diameter recess 25, and the one end 14 of the bolt insertion hole 18 of the bearing body 2 is aligned with the female screw hole 32 of the bearing body 5, and then the bearing body 2 and the bearing body 5 are screwed and integrated by inserting the hexagon socket bolt as the tightening member 4 through the bolt insertion hole 18 and screwing the male screw portion of the hexagon socket bolt into the female screw hole 32 of the bearing body 5, thereby forming the assembly 70.

In the same manner as described above, the other surface 26 of the bearing body 5 in the assembled body 70 screwed and integrated as described above is irradiated with a laser beam by a laser processing machine to form the annular recessed groove 27 having a width W of 0.3 to 1.0mm and a depth D of 0.01 to 0.05mm and the plurality of air blowing holes 31 having a shape of a throttle hole, and the air blowing holes 25 are formed in the annular surface 33 forming the annular recessed groove 27, penetrate the bearing body 5 from the annular surface 33 and are opened to the annular bottom surface 30 of the annular recess 22, and have a diameter D of at least 30 μm, preferably 30 to 120 μm.

In the hydrostatic gas bearing 1 formed as described above, as shown in fig. 27, the ball 54 of the ball pin 53 is disposed in sliding contact with the frustoconical surface 66 of the recess 67 of the block 68 fitted and fixed to the other surface 17 of the bearing base 2, and thus has an automatic centering function.

Fig. 28 to 31 show another embodiment of the hydrostatic gas bearing 1 having the self-aligning function. A cylindrical recess 59 having an opening 57 which is circular in a plan view and a circular bottom surface 58 is formed in a central portion of the other plane 17 which is circular in a plan view of the bearing base 2, and as shown in fig. 28, a block 68 is fitted and fixed to the cylindrical recess 59 with one plane 62 facing the bottom surface 58 of the cylindrical recess 59, wherein the block 68 includes: a cylindrical body 60; a circular hole 63 having one end 61 opened to one surface 62 of the cylindrical body 60; and a concave portion 67 having a concave spherical surface 69 connected to the other end 64 of the circular hole 63 and expanding from the other end 64 toward the other surface 65.

Similarly to the above-described static pressure gas bearing 1, the bearing body 2 to which the block 68 is fitted and fixed is configured such that the opening 8 of the air supply hole 9 communicates with the opening 36 of the annular recess 22 of the bearing body 5 to which the o-ring is attached in the enlarged diameter recess 25, and the one end 14 of the bolt insertion hole 18 of the bearing body 2 is aligned with the female screw hole 32 of the bearing body 5, and then the bearing body 2 and the bearing body 5 are screwed and integrated by inserting the hexagon socket bolt as the tightening member 4 through the bolt insertion hole 18 and screwing the male screw portion of the hexagon socket bolt into the female screw hole 32 of the bearing body 5, thereby forming the assembly 71.

In the same manner as described above, the other surface 26 of the bearing body 5 in the assembled body 71 screwed and integrated as described above is irradiated with a laser beam by a laser processing machine to form the annular recessed groove 27 having a width W of 0.3 to 1.0mm and a depth D of 0.01 to 0.05mm and the plurality of air blowing holes 31 having a shape of a throttle hole, and the air blowing holes 25 are formed in the annular surface 33 forming the annular recessed groove 27, penetrate the bearing body 5 from the annular surface 33 and are opened to the annular bottom surface 30 of the annular recess 22, and have a diameter D of at least 30 μm, preferably 30 to 120 μm.

In the hydrostatic gas bearing 1 formed as described above, as shown in fig. 31, the ball 54 of the ball pin 53 is disposed in sliding contact with the concave spherical surface 69 of the concave portion 67 of the block 68 fitted and fixed in the cylindrical concave portion 59 of the bearing base 2, and thus has an automatic aligning function.

Since the block 68 fitted and fixed to the cylindrical concave portion 59 formed in the central portion of the other circular surface 17 in plan view of the bearing base body 2 is formed of a material having excellent sliding properties, for example, a thermoplastic synthetic resin having self-lubricating properties such as a polyacetal resin, a polyamide resin, or a polyester resin, or copper or a copper alloy, the sliding contact between the truncated conical surface 66 or the concave spherical surface 69 of the concave portion 67 of the block 68 and the ball 54 of the ball pin 53 can be performed more smoothly.

Fig. 32 shows a linear guide device 72 using the static pressure gas bearing 1 shown in fig. 27, wherein the linear guide device 72 is formed by a guide member 75, a movable table 78 having an コ -shaped cross section, a ball pin 53, and the static pressure gas bearing 1, wherein the guide member 75 has an upper guide surface 73 and both side guide surfaces 74, 74 as guide surfaces, the movable table 78 is disposed over the guide member 75, the movable table 78 includes an upper plate 76 facing the upper guide surface 73 and a pair of side plates 77, 77 facing the both side guide surfaces 74, the ball pin 53 fixes the ball 54 inwardly to a lower surface 79 of the upper plate 76 of the movable table 78 and inner surfaces 80, 80 of the pair of side plates 77, respectively, the static pressure gas bearing 1 is disposed between the ball pin 53 and the upper guide surface 73 and both side guide surfaces 74, 74 of the guide member 75, and the truncated conical surface 66 of the block 68 is brought into sliding contact with the ball 54 of the ball pin 53 to bring one surface 26 of the bearing body 5 into sliding contact with the upper surface 73 and the guide surface 73 and the The two side guide surfaces 74, 74 are opposed.

According to the linear guide device 72, since the compressed air is injected from the plurality of air blowing holes 31 of the bearing body 5 to the upper guide surface 73 and the both side guide surfaces 74, 74 of the guide member 75, the movable table 78 can be kept in a non-contact state with respect to the upper guide surface 73 and the both side guide surfaces 74, 74 by the air lubrication film formed between the upper guide surface 73 and the both side guide surfaces 74, 74. If the bearing gaps between the bearing body 5 and the upper guide surface 73 and the both side guide surfaces 74, 74 are not uniform, a pressure difference occurs in each portion of the bearing gap, but the hydrostatic gas bearing 1 can be automatically centered in the direction in which the bearing gap is uniform due to the pressure difference, and can be maintained in a state of being parallel to the upper guide surface 73 and the both side guide surfaces 74, 74. Therefore, the accuracy of the components such as the parallelism and the squareness of the guide member 75 and the movable table 78 can be set to a high level, and the cost of the hydrostatic gas bearing 1 itself can be reduced, and the linear guide device 72 can be easily manufactured and the cost can be reduced.

In the linear guide device 72, the hydrostatic gas bearing 1 shown in fig. 16, 20, and 31 may be used as the hydrostatic gas bearing 1 having the automatic aligning function.

As described above, since the bearing body and the bearing base body are screwed and integrated via the annular seal member, the joint surface between the bearing body and the bearing base body is firmly sealed, an annular recess and a plurality of air blow-out holes each having a shape of a throttle hole are formed on one surface of the bearing body, wherein the width W of the annular groove is 0.3-1.0 mm, the depth d is 0.01-0.05 mm, the air blowing hole penetrates the bearing body from the annular surface on the annular surface forming the annular groove and is opened on the annular bottom surface of the annular concave part, having a diameter D of at least 30 μm, since the annular groove and the air blowing holes can be formed without machining, therefore, not only can a mass-producible and inexpensive hydrostatic gas bearing be provided, but also a linear motion guide device which is easy to manufacture and which is cost-reduced by using the hydrostatic gas bearing can be provided.

Claims (11)

1. A hydrostatic gas bearing, comprising:

a synthetic resin-made bearing body having an annular recess formed in one surface of the bearing body, an annular shoulder surface connected to an outer peripheral wall surface of the annular recess and having a diameter larger than that of the outer peripheral wall surface, an annular groove opened in the other surface of the bearing body, and a plurality of air blowing holes opened at one end to the annular groove and at the other end to an annular bottom surface of the annular recess;

an annular seal member mounted in contact with the annular shoulder surface; and

a bearing base body having an air supply passage on one surface facing one surface of a bearing body, the air supply passage being open at one end to the one surface of the bearing base body facing the one surface of the bearing body and being open at the other end to an outer peripheral surface of the bearing base body,

the bearing body is integrated with the bearing body by communicating an opening of the annular recess with an air supply passage of the bearing body and being fastened and fixed to the bearing body by a plurality of fastening members, the annular groove has a width of at least 0.3mm and a depth of at least 0.01mm, the air blow-out hole has a diameter of at least 30 μm at one end thereof, and a self-throttling hole is formed between the annular recess and the annular groove.

2. The hydrostatic gas bearing of claim 1,

the annular groove has a width of 0.3 to 1.0mm or 0.3 to 0.7mm, a depth of 0.01 to 0.05mm or 0.01 to 0.03mm, and the air blowing hole has a diameter of 30 to 120 μm at one end thereof.

3. The hydrostatic gas bearing of claim 1 or 2,

the annular groove and the air blow hole are formed by laser processing, respectively.

4. The hydrostatic gas bearing of any of claims 1-3,

the inner peripheral wall surface of the annular recess is formed as a truncated conical surface gradually expanding from the opening toward the annular bottom surface.

5. The hydrostatic gas bearing of any of claims 1-4,

a ball pressure receiving recess is formed in the other surface of the bearing base.

6. The hydrostatic gas bearing of claim 5,

the ball pressure receiving recess has a truncated conical recess opening on the other surface of the bearing base.

7. The hydrostatic gas bearing of claim 5,

the ball pressure receiving recess has a concave spherical surface portion that opens to the other surface of the bearing base.

8. The hydrostatic gas bearing of claim 5,

the ball pressure receiving recess includes a cylindrical recess having an opening on the other surface of the bearing base, and a block is fitted and fixed to the cylindrical recess, the block having a truncated conical recess on one surface and having the truncated conical recess open to the opening of the cylindrical recess.

9. The hydrostatic gas bearing of claim 5,

the ball pressure receiving recess includes a cylindrical recess having an opening on the other surface of the bearing base, and a block is fitted and fixed to the cylindrical recess, the block having a concave spherical surface portion on one surface, and the concave spherical surface portion being opened to the opening of the cylindrical recess.

10. The hydrostatic gas bearing of any of claims 1-9,

the bearing body includes, in addition to the annular groove:

a large-diameter annular groove formed on one surface of the bearing body and surrounding the annular groove on an outer side thereof;

a plurality of first radial grooves, one end of each of which opens into the annular groove, and the other end of each of which opens into the large-diameter annular groove;

a small-diameter annular groove formed inside the annular groove; and

and a plurality of second radial grooves, one end of each of which opens into the annular groove, and the other end of each of which opens into the small-diameter annular groove.

11. A linear motion guide device is characterized in that,

a movable table having an upper plate opposed to an upper guide surface and a pair of side plates opposed to both guide surfaces is disposed outside a guide member having the upper guide surface and both guide surfaces as the guide surfaces, ball pins are erected on the lower surface of the upper plate and the inner surfaces of the pair of side plates of the movable table with balls facing inward, and the hydrostatic gas bearing according to any one of claims 1 to 10 is disposed between the ball pins and the upper surface and both side surfaces of the guide member, and the bearing body is opposed to the upper guide surface and both guide surfaces of the guide member by bringing a ball pressure receiving recess into sliding contact with the ball of the ball pin.