JP4379126B2 - Gap adjusting device for hydrostatic gas bearing pad and hydrostatic gas bearing mechanism using the same - Google Patents

Description

  The present invention relates to a gap adjusting device that adjusts a gap between a movable body that holds the movable body movably with respect to the fixed body and the movable body of the static pressure gas bearing pad interposed between the fixed body and the movable body. The present invention relates to a static pressure gas bearing mechanism using the same.

JP-A-8-28564 JP 2000-199522 A Japanese Patent Application Laid-Open No. 2002-349569

  Hydrostatic gas bearings, especially porous hydrostatic gas bearings using porous metal sintered bodies, are known as bearings with excellent high-speed stability, high load capacity, and extremely low movement resistance, and these excellent It is used in many fields because of its advantages. When such a static pressure gas bearing is interposed between the movable body and the fixed body in a pad form (in the present invention, the pad-shaped static pressure gas bearing is referred to as a static pressure gas bearing pad), normally, The static pressure gas bearing pad is arranged with a minute gap between them, for example, a gap of about 5 μm.

  Since this gap greatly affects the bearing rigidity, load capacity and speed characteristics, the static pressure gas bearing pad is located between the movable body and the fixed body via a gap adjustment device that can adjust the gap between the movable body and the movable body. However, after adjustment of the gap, the adjustment and setting state of the gap adjustment device is fixed so as to be releasable so that the set gap does not change.

  By the way, in a gap adjusting device attached to a fixed body, generally, a screw is used to adjust and set a minute gap by changing the screwed state of the screw, and after adjustment, the screw is not moved by a double nut. However, in the case of fixing with a double nut, since the nut is screwed into the screw after adjustment, there is a risk that the screw will slightly move due to the minute rotation of the screw by screwing the nut. In addition, since the two nuts are screwed together with the screws, the fixing work becomes complicated, and the two nuts and the portion of the screw into which these nuts are screwed project from the fixed body. This requires unnecessary space.

  The present invention has been made in view of the above points, and the object of the present invention is to fix the set state without changing the adjusted state after adjusting the gap, that is, the set state. It is another object of the present invention to provide a gap adjusting device for a hydrostatic gas bearing pad that can be easily installed and installed in a small space, and a hydrostatic gas bearing mechanism using the same.

  According to the first aspect of the present invention, the gap between the movable body that holds the movable body relative to the fixed body and the movable body of the static pressure gas bearing pad interposed between the movable body and the fixed body is adjusted. The gap adjusting device includes a cylindrical body having an internal thread engraved on an inner peripheral surface thereof, and an advanceable / retractable member that has an external thread on the outer peripheral surface thereof that engages with an internal thread of the inner peripheral surface of the cylindrical body and protrudes from one end surface of the cylindrical body. And a fixing means for fixing the position of the advanceable / retractable member with respect to the cylinder, and the cylinder is provided with a slit extending from the outer peripheral surface to at least the inner peripheral surface, and the fixing means has a width of the slit. The position of the advanceable / retractable member with respect to the cylinder is fixed by applying a force in the direction of changing the cylinder to the cylinder.

  According to the gap adjusting device of the first aspect, the fixing device is provided that fixes the position of the advanceable / retractable member with respect to the cylinder by applying a force in the direction of changing the slit width of the cylinder to the cylinder. Therefore, in the fixing operation for fixing the position of the advanceable / retractable member with respect to the cylinder by the fixing means after adjusting the gap, the advanceable / retractable member is not rotated, and as a result, the setting state is changed without changing the setting state of the gap. Can be fixed.

  As in the gap adjusting device according to the second aspect of the present invention, the fixing means includes a screw hole provided in the cylindrical body and opened on the other end surface of the cylindrical body and one slit surface of the cylindrical body defining the slit. Even if the fixing screw screwed into the screw hole is provided, like the gap adjusting device of the third aspect of the present invention, the other end surface of the cylinder and one slit surface of the cylinder defining the slit The through hole provided in the cylindrical body opened at the opening and the opening on the other slit surface of the cylindrical body defining the slit while facing the opening on one slit surface of the through hole provided on the cylindrical body The former may have a screw hole and a fixing screw that has a huge portion locked to the other end surface of the cylinder and is movably inserted into the through hole, and is screwed into the screw hole. The fixing screw is a cylinder that defines the slit in the direction of widening the slit width of the cylinder. In order to press the other slit surface, one end projecting from one slit surface is in contact with the other slit surface and the other end is preferably screwed into the screw hole. The fixing screw is screwed into the screw hole at one end and enormous at the other end so as to attract one slit surface relative to the other slit surface in the direction of narrowing the slit of the cylindrical body. The part may be locked to the other end surface of the cylinder.

  According to the gap adjusting device of the second or third aspect, the position of the advanceable / retractable member relative to the cylinder can be fixed by advancing and retracting the fixing screw with respect to the cylinder, so that the gap is set after the gap adjustment. Fixing work can be easily performed without changing the state, and the fixing screw can be advanced and retracted in the screw hole or screw hole and through hole, so that the fixing screw does not protrude from the cylinder body and is installed in a small space. it can.

  The cylindrical body is preferably a hollow body having an annular one end surface and the other end surface and a cylindrical inner peripheral surface and an outer peripheral surface, as in the gap adjusting device according to the fourth aspect of the present invention, and the hollow body. And a flange provided integrally on the outer peripheral surface on the one end face side, wherein the female screw is engraved on the inner peripheral surface of the hollow body.

  When the gap adjusting device is used for a static pressure gas bearing mechanism, the cylinder is mounted in the through hole of the fixed body and fixed to the fixed body. The fixing of the cylindrical body to the fixed body is performed by fitting. Any means of welding, screwing may be used. In this case, if the cylindrical body has a flange as in the gap adjusting device of the fourth aspect, the fixing body is fixed in the through hole. The cylindrical body can be easily positioned with respect to the body.

  The cylindrical body may also include a hollow body having an annular one end surface and the other end surface and having a cylindrical inner peripheral surface and an outer peripheral surface as in the gap adjusting device according to the fifth aspect of the present invention. In this case, an annular groove is provided on the outer peripheral surface of the hollow body, and an elastic ring partially protruding from the outer peripheral surface of the hollow body is attached to the annular groove, and the female screw is hollow. It is good to be engraved on the inner peripheral surface of the body.

  When the elastic ring is mounted in the annular groove as in the clearance adjustment device of the fifth aspect, when the cylindrical body is mounted in the through hole of the stationary body of the static pressure gas bearing mechanism, the elastic ring is installed in the through hole. Since the cylindrical body can be temporarily fixed to the fixed body, the subsequent work becomes easy.

  The cylindrical body does not necessarily have a flange, but the cylindrical body is one of the hollow bodies as in the clearance adjustment apparatus of the sixth aspect of the present invention even in the clearance adjustment apparatus of the fifth aspect. A flange provided integrally on the outer peripheral surface on the end face side may be further provided, and when such a flange is provided, the clearance adjustment device according to the fourth aspect is provided to the through hole of the fixed body. Therefore, the cylindrical body can be easily positioned with respect to the fixed body.

  The front end surface of one end of the advanceable / retractable member protruding from the one end surface of the cylindrical body may be a flat surface or a convex curved surface, but preferably from a semi-convex spherical surface as in the gap adjusting device of the seventh aspect of the present invention. Thus, if the tip surface is made of such a semi-convex spherical surface, the hydrostatic gas bearing pad can be swung without being constrained by the tip surface, and the static pressure gas bearing pad faces the movable body with a uniform gap. be able to.

  In a preferred example, the advanceable / retractable member is a cylindrical body or a cylindrical body having a male screw threadedly engaged with a female screw on the outer peripheral surface, as in the gap adjusting device according to the eighth aspect of the present invention, and one end portion of the cylindrical body or the cylindrical body. The tip end surface of the one end part of the advanceable / retractable member protruding from the one end surface of the cylinder is made of a part of the surface of the sphere or the surface of the hemisphere.

  When the tip surface is a part of the surface of a sphere or the surface of a hemisphere as in the gap adjustment device of the eighth aspect, the tip surface is a semi-convex spherical surface. Similarly, the hydrostatic gas bearing pad can be swung without being constrained by the tip surface, and the hydrostatic gas bearing pad can be made to face the movable body with a uniform gap.

  A static pressure gas bearing mechanism according to a first aspect of the present invention includes a static pressure gas bearing pad interposed between a movable body and a fixed body that holds the movable body with respect to the fixed body, and a static pressure gas bearing pad. The gap adjusting device according to any one of the above aspects is mounted on a fixed body that adjusts the gap between the pressurized gas bearing pad and the movable body.

  The static pressure gas bearing pad preferably has a porous surface facing the movable body like the static pressure gas bearing mechanism of the second aspect of the present invention, and the static pressure gas bearing mechanism of the third aspect. In this case, one surface of the porous metal sintered layer is a porous surface facing the movable body.

  As the porous metal sintered layer, a metal powder and an inorganic powder mixed and sintered can be cited as a preferred example, where the metal powder contains at least tin, phosphorus and copper, Furthermore, it is preferable that at least one of nickel and manganese is included, and the inorganic powder includes at least one of graphite, boron nitride, graphite fluoride, calcium fluoride, aluminum oxide, silicon oxide, and silicon carbide. Although it is good to include, this invention is not limited to these.

  The static pressure gas bearing pad has a concave surface with which the tip surface of one end portion of the advanceable / retractable member protruding from one end surface of the cylindrical body abuts like the static pressure gas bearing mechanism of the fourth aspect of the present invention. If the concave surface is provided, unintended movement of the static pressure gas bearing pad can be prevented, and the static pressure gas bearing pad can always be held at the initial arrangement position.

  In the static pressure gas bearing mechanism of the fourth aspect, it is preferable that the concave surface has a shape that is complementary to the shape of the tip surface and closely matches the tip surface. More preferably, it is a semi-concave spherical surface like a static pressure gas bearing mechanism, and particularly when the tip surface is a semi-convex spherical surface, the hydrostatic gas bearing pad is not restrained by the tip surface. Further, it becomes possible to face the movable body with a more uniform gap. In this case, each of the semi-concave spherical surface and the semi-convex spherical surface is preferably mirror-finished or the like so that it can slide with a low frictional resistance.

  According to the present invention, the setting state can be fixed without changing the setting state after adjustment, and the fixing operation can be easily performed, and the gap adjusting device for a hydrostatic gas bearing pad that can be installed with a small space, and the same The used static pressure gas bearing mechanism can be provided.

  Next, the present invention and the best mode for carrying it out will be described in more detail based on the preferred embodiments shown in the drawings. The present invention is not limited to these examples.

  1 to 6, the static pressure gas bearing mechanism 1 of this example is interposed between the movable body 2 and the fixed body 3 that hold the movable body 2 movably in the X direction with respect to the fixed body 3. A plurality of static pressure gas bearing pads 4 and a fixed body 3 that adjusts a gap 5 between each static pressure gas bearing pad 4 and the movable body 2 are mounted corresponding to each static pressure gas bearing pad 4. The gap adjusting device 6 is provided.

  Each of the movable body 2 and the fixed body 3 is composed of a rectangular plate and a U-shaped rail in this example. However, when the static pressure gas bearing mechanism 1 is applied to, for example, a precision machine tool. The movable body 2 has a form suitable for the work head itself, the base on which the work head is placed, or the work placing base, and the fixed body 3 also holds the movable body 2 having such a form in a movable manner in the X direction. Therefore, the movable body 2 and the fixed body 3 are not limited to the rectangular plate and the U-shaped rail, respectively.

  A plurality of static pressure gas bearing pads 4 interposed between the side surfaces 11 and 12 of the movable body 2 and the inner side surfaces 13 and 14 of the fixed body 3, and the bottom surface 15 of the movable body 2 and the base upper surface 16 of the fixed body 3, respectively. The plurality of static pressure gas bearing pads 4 interposed between the two are configured in the same manner, and the gap adjusting device 6 mounted on the fixed body 3 corresponding to each static pressure gas bearing pad 4. Are configured in the same manner, and hereinafter, the static pressure gas bearing pad 4 interposed between the side surface 11 of the movable body 2 and the inner side surface 13 of the fixed body 3 and the static pressure gas bearing pad 4 will be described below. Correspondingly, the gap adjusting device 6 attached to the fixed body 3 will be described in detail.

  The hydrostatic gas bearing pad 4 includes a disc-shaped back metal 23 having a concave surface 22 formed of a semi-concave spherical surface at a substantially central portion of a flat surface 21 facing the inner surface 13 of the fixed body 3, and the other flat surface of the back metal 23. And a disc-shaped porous metal sintered layer 25 which is formed and fixed integrally with the back metal 23 and forms a gas passage 24 in cooperation with the back metal 23, via a flexible pipe 26. The high-pressure air supplied to the gas passage 24 is jetted toward the side surface 11 of the movable body 2 through a large number of pores of the porous metal sintered layer 25. As described above, the static pressure gas bearing pad 4 has the porous surface 27 facing the side surface 11 of the movable body 2, and one flat surface of the porous metal sintered layer 25 is the porous surface 27. .

  The gap adjusting device 6 that adjusts the gap 5 between the porous surface 27 of the static pressure gas bearing pad 4 and the side surface 11 of the movable body 2 includes a cylindrical body 33 in which an internal thread 32 is engraved on an inner peripheral surface 31, and an internal thread. An advancing / retracting member 37 having an external thread 35 screwed to the outer peripheral surface 35 and protruding from one end surface 36 of the cylindrical body 33; and a fixing means 39 for fixing the position of the advancing / retreating member 37 in the Y direction with respect to the cylindrical body 33; It has.

  The cylindrical body 33 is integrated with a hollow body 43 having an annular one end face 36 and other end face 41 and a cylindrical inner peripheral face 31 and an outer peripheral face 42, and an outer peripheral face 42 on the one end face 36 side of the hollow body 43. The hollow body 43 of the cylindrical body 33 extends from the outer peripheral surface 42 to at least the inner peripheral surface 31. In this example, the slit extends beyond the inner peripheral surface 31. 45, an annular groove 46 is provided on the outer peripheral surface 42 of the hollow body 43, and the annular groove 46 is an elastic ring partially protruding from the outer peripheral surface 42 of the hollow body 43, for example, O A ring 47 is attached, and the female screw 32 is engraved on the inner peripheral surface 31 of the hollow body 43.

  The cylindrical body 33 is inserted into a stepped through hole 48 formed in the fixed body 3 and is fitted into the fixed body 3, and the collar portion 44 is brought into contact with an annular shoulder portion 49 that defines the stepped portion of the through hole 48. It is touched and mounted.

  The advanceable / retractable member 37 is a cylindrical body or cylindrical body having a male screw 34 on the outer peripheral surface 35, in this example, a cylindrical body 51, and a sphere or hemisphere that is fixedly attached to one end 52 of the cylindrical body 51, in this example. The tip surface 54 of the one end 52 of the advanceable / retractable member 37 protruding from the one end surface 36 of the cylindrical body 33 is a part of the surface of the sphere or the surface of the hemisphere, in this example, the sphere 53. The surface 55 of the cylindrical body 51 is a semi-convex spherical surface and is in contact with the concave surface 22 of the hydrostatic gas bearing pad 4. A hexagonal recess 58 is provided for inserting the.

  The advanceable / retractable member 37 screwed into the inner peripheral surface 31 of the cylindrical body 33 via the male screw 34 and the female screw 32 is inserted into the hexagonal recess 58 with one end of the rotary tool and is rotated around the axis O by the rotary tool. When the rotation is performed in the R direction, the male screw 34 and the female screw 32 are screwed together so that the cylindrical body 33 is advanced and retracted in the Y direction. The static pressure gas bearing pad 4 is moved in the Y direction for adjustment.

  The fixing means 39 is opened at the other end surface 41 of the hollow body 43 of the cylindrical body 33 and one slit surface 61 of the cylindrical body 33 defining the slit 45, and is provided in the screw body 62 provided in the hollow body 43 of the cylindrical body 33. And a fixing screw 63 screwed into the screw hole 62.

  The fixing screw 63 comes into contact with the slit surface 65 at one end 66 protruding from the slit surface 61 so as to press the other slit surface 65 of the cylindrical body 33 that defines the slit 45 in the direction of increasing the width W of the slit 45. The other end 67 is screwed into the screw hole 62, and a hexagonal recess 69 for inserting a rotary tool is provided on the end face 68 of the other end 67.

  After the width t of the gap 5 is adjusted and set by the advance and retreat of the advanceable / retractable member 37 in the Y direction, the fixing means 39 inserts one end of the rotary tool into the hexagonal recess 69 and attaches the fixing screw 63 with the rotary tool. The fixing screw 63 is further screwed into the screw hole 62, and the force in the direction to change the width W of the slit 45 by strongly pressing the slit surface 65 at one end 66, in this example, the direction of increasing the width W of the slit 45. This force is applied to the hollow body 43 of the cylindrical body 33, thereby causing deformation in the hollow body 43 in the vicinity of the slit 45 so that the advanceable / retractable member 37 cannot advance or retract in the Y direction with respect to the hollow body 43 of the cylindrical body 33. Thus, the position of the advanceable / retractable member 37 with respect to the hollow body 43 of the cylindrical body 33 is fixed.

  In order to prevent the advanceable / retractable member 37 from moving back and forth in the Y direction, it is not necessary to cause obvious deformation distortion in the hollow body 43 in the vicinity of the slit 45, and the advanceable / retractable member 37 cannot be rotated in the R direction. A force that causes a slight deformation distortion in the hollow body 43 in the vicinity of the slit 45 may be simply applied to the hollow body 43 through pressing the slit surface 65 of the one end 66.

  According to the gap adjusting device 6 including a fixing means 39 configured to apply a force in a direction to change the width of the slit 45 of the cylindrical body 33 to the cylindrical body 33 to fix the position of the advanceable / retractable member 37 with respect to the cylindrical body 33. For example, in the fixing operation for fixing the position of the advanceable / retractable member 37 relative to the cylindrical body 33 by the fixing means 39, the settable state can be fixed without changing the set state of the gap 5 as a result of not causing the advanceable / retractable member 37 to rotate. Moreover, the position of the advanceable / retractable member 37 in the Y direction relative to the cylinder 33 is fixed by rotating the fixing screw 63 with respect to the cylinder 33 and advancing / retreating the fixing screw 63 with respect to the cylinder 33 by screwing with the screw hole 62. As a result, the fixing operation can be easily performed without changing the set state of the gap 5, and the fixing screw 63 can be advanced and retracted in the screw hole 62. It without projecting from the cylindrical body 33 can be installed with a small space.

  Further, in the gap adjusting device 6, since the cylindrical body 33 includes the flange portion 44, the cylindrical body 33 can be easily positioned with respect to the fixed body 3 when the fixed body 3 is mounted in the through hole 48. When the cylindrical body 33 is mounted in the through hole 48 of the fixed body 3 because the ring 47 is mounted in the annular groove 46, the cylindrical body 33 is temporarily attached to the fixed body 3 through the O ring 47 in the through hole 48. Since it can be stopped, the subsequent work is facilitated. In addition, since the front end surface 54 of the advanceable / retractable member 37 is a semi-convex spherical surface, the hydrostatic gas bearing pad 4 can be swung without being constrained by the front end surface 54. The static pressure gas bearing pad 4 can be made to face the movable body 2 with a uniform gap 5.

  Since the static pressure gas bearing pad 4 has the concave surface 22 with which the front end surface 54 of the advanceable / retractable member 37 is slidably contacted, the unintended movement of the static pressure gas bearing pad 4 in the X direction is prevented. Since the pressurized gas bearing pad 4 is always held at the initial arrangement position and the concave surface 22 is a semi-concave spherical surface, the static pressure gas bearing pad 4 can be further oscillated without being constrained by the tip surface 54. Thus, the movable body 2 can be faced with a more uniform gap 5.

  In the above example, a force in the direction of expanding the width W of the slit 45 by pressing the slit surface 65 with the one end portion 66 of the fixing screw 63 is applied to the hollow body 43 of the cylindrical body 33, thereby the hollow body 43 of the cylindrical body 33. The position of the advanceable / retractable member 37 in the Y direction is fixed, but instead of this, as shown in FIG. In addition to the body 43, the position of the advanceable / retractable member 37 in the Y direction with respect to the hollow body 43 of the cylinder 33 may be fixed thereby. In this case, the cylinder defining the other end surface 41 and the slit 45 of the cylinder 33 A through-hole 71 provided in the hollow body 43 of the cylindrical body 33 by opening at one slit surface 61 of the body 33, and facing the opening at one slit surface 61 of the through-hole 71 and defining the slit 45. Other than cylinder 33 The screw hole 72 provided in the hollow body 43 of the cylindrical body 33 that opens at the slit surface 65 of the cylindrical body 33, and the other end surface 41 of the cylindrical body 33, in this example, the enormous amount that is engaged with the circular recess 73 of the other end surface 41. The fixing means 39 is configured by including a fixing screw 63 that has a portion 74 and is movably inserted into the through hole 71, and is screwed into the screw hole 72 at one end portion 66, thereby forming the hollow body 43 of the cylindrical body 33. The fixing screw 63 is screwed into the screw hole 72 at one end portion 66 and the other end portion so that the one slit surface 61 is relatively attracted to the other slit surface 65 in the direction of narrowing the width W of the slit 45. The fixing means 39 may be configured by engaging with the recess 73 of the other end surface 41 of the cylindrical body 33 in the enlarging portion 74 of 67. In this case as well, the end surface 75 of the enlarging portion 74 rotates on the end surface 75 as described above. A hexagonal recess is provided to insert the tool. After the width t of the gap 5 is adjusted and set by the advance and retreat of the universal member 37 in the Y direction, one end portion of the rotary tool is inserted into the hexagonal recess provided in the enormous portion 74 and the fixing screw 63 is attached by the rotary tool. By rotating, a force in the direction of narrowing the width W of the slit 45 is applied to the hollow body 43 of the cylindrical body 33, thereby causing deformation in the hollow body 43 in the vicinity of the slit 45 and causing the hollow body 43 of the cylindrical body 33 to deform. On the other hand, the advanceable / retractable member 37 may be prevented from advancing / retreating in the Y direction, and the position of the advanceable / retractable member 37 in the Y direction with respect to the hollow body 43 of the cylindrical body 33 may be fixed.

It is plane explanatory drawing of a preferable example of embodiment of this invention. It is a perspective view of the clearance gap adjustment apparatus shown in the example of FIG. It is a rear view of the clearance gap adjustment apparatus shown in FIG. FIG. 3 is a cross-sectional explanatory view of the gap adjusting device shown in FIG. 2. It is a side view of the member which can be advanced / retracted used for the clearance gap adjustment apparatus shown in FIG. It is a whole perspective view of the example shown in FIG. It is sectional explanatory drawing of the other preferable example of embodiment of the clearance gap adjustment apparatus in this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Static pressure gas bearing mechanism 2 Movable body 3 Fixed body 4 Static pressure gas bearing pad 5 Gap 6 Gap adjustment apparatus

Claims (6)

  A clearance adjustment device that adjusts a clearance between a movable body of a static pressure gas bearing pad that is interposed between the movable body and the fixed body to hold the movable body movably with respect to the fixed body, A cylindrical body having a slit extending from the surface to at least the inner peripheral surface and having an internal thread engraved on the inner peripheral surface, and a male thread threadedly engaged with the female screw on the inner peripheral surface of the cylindrical body An advanceable / retractable member that protrudes from one end surface of the member, and a fixing means that fixes the position of the advanceable / retractable member with respect to the cylinder by applying a force in a direction to change the width of the slit to the cylinder, A cylindrical body having a male screw threadedly engaged with the female thread on the outer peripheral surface; and a sphere fixedly provided at one end of the cylindrical body; The tip surface is a semi-convex spherical surface and consists of part of the surface of the sphere. The fixing means includes a screw hole provided in the cylinder body that is opened at the other end surface of the cylinder body and one slit surface of the cylinder body that defines the slit, and a fixing screw that is screwed into the screw hole. The fixing screw has the other slit surface at one end protruding from one slit surface so as to press the other slit surface of the cylinder defining the slit in the direction of widening the slit width of the cylinder. The hydrostatic gas bearing pad has a porous metal sintered layer having a porous surface facing the movable body on one surface and a cylindrical body. A clearance adjustment device for a hydrostatic gas bearing pad, which has a concave surface with which a front end surface of one end portion of an advanceable / retractable member protruding from an end surface abuts, and the concave surface is a semi-concave spherical surface.   A clearance adjustment device that adjusts a clearance between a movable body of a static pressure gas bearing pad that is interposed between the movable body and the fixed body to hold the movable body movably with respect to the fixed body, A cylindrical body having a slit extending from the surface to at least the inner peripheral surface and having an internal thread engraved on the inner peripheral surface, and a male thread threadedly engaged with the female screw on the inner peripheral surface of the cylindrical body An advanceable / retractable member that protrudes from one end surface of the member, and a fixing means that fixes the position of the advanceable / retractable member with respect to the cylinder by applying a force in a direction to change the width of the slit to the cylinder, A cylindrical body having a male screw threadedly engaged with the female thread on the outer peripheral surface; and a sphere fixedly provided at one end of the cylindrical body; The tip surface is a semi-convex spherical surface and consists of part of the surface of the sphere. The fixing means includes a through-hole provided in the cylinder by opening the other end surface of the cylinder and one slit surface of the cylinder defining the slit, and an opening at one slit surface of the through-hole. It has a screw hole that is opened in the other slit surface of the cylinder that faces and defines the slit and is provided in the cylinder, and a huge portion that is locked to the other end surface of the cylinder, and is movably inserted into the through hole. On the other hand, a fixing screw that is screwed into the screw hole is provided, and the fixing screw attracts one slit surface relatively to the other slit surface in a direction of narrowing the width of the slit of the cylindrical body. In addition, the one end is screwed into the screw hole, and the enormous portion at the other end is locked to the other end surface of the cylinder, and the static pressure gas bearing pad is a porous surface facing the movable body on one surface. A porous metal sintered layer having a surface and a protrusion protruding from one end surface of the cylinder. The distal end surface of the one end portion of the movable member has a concave abutting, concave gap adjusting device for a hydrostatic gas bearing pad has a semi-spherical concave.   The cylindrical body has an annular one end surface and the other end surface, and has a cylindrical inner peripheral surface and an outer peripheral surface, and a flange portion integrally provided on the outer peripheral surface on the one end surface side of the hollow body. The gap adjusting device according to claim 1, wherein the female screw is engraved on the inner peripheral surface of the hollow body.   The cylindrical body has a hollow body having an annular one end face and other end face and a cylindrical inner peripheral face and an outer peripheral face, and an annular groove is provided on the outer peripheral face of the hollow body. The clearance adjustment according to claim 1 or 2, wherein an elastic ring partially protruding from the outer peripheral surface of the hollow body is attached to the annular groove, and the female screw is engraved on the inner peripheral surface of the hollow body. apparatus.   The gap adjusting device according to claim 4, wherein the cylindrical body further includes a flange portion integrally provided on an outer peripheral surface on one end surface side of the hollow body.   The movable body is held movably with respect to the fixed body. The static pressure gas bearing pad interposed between the movable body and the fixed body, and the gap between the static pressure gas bearing pad and the movable body are adjusted. A static pressure gas bearing mechanism comprising the gap adjusting device according to any one of claims 1 to 5, which is mounted on a fixed body.

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