JP2013010159A - Hydrostatic gas bearing spindle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydrostatic gas bearing spindle that can limit changes in a position of a fitting surface.SOLUTION: The hydrostatic gas bearing spindle that is affixed to a mounting surface (PS) is provided with: a pivot (1) having the fitting surface (1a) on an end face; a housing (2) that surrounds the outer circumferential surface of the pivot (1) with a bearing clearance (10), into which a bearing gas for rotatably supporting the pivot (1) is supplied, therebetween; and first fixing boards (3) and second fixing boards (4) that are disposed at a distance from each other in the direction of the axial line (AX) of the housing (2) and are for fixing the housing (2) to the mounting surface (PS). The second fixing boards (4), which are disposed at positions that are farther from the fitting surface (1a) than the first fixing boards (3), comprise a linear guide mechanism (5) that is capable of linear guidance in the axial direction (AX).

Description

  The present invention relates to a static pressure gas bearing spindle, and more particularly to a static pressure gas bearing spindle fixed to an installation surface.

  Static pressure gas bearing spindles are used in precision machining equipment and precision inspection equipment. In particular, when a static pressure gas bearing spindle is used in a precision machining apparatus, it is desirable that a change in the position of a workpiece mounting surface (mounting surface) on which a workpiece (workpiece) is fixed is small in order to perform high-precision machining.

  However, thermal expansion occurs in the components of the hydrostatic gas bearing spindle due to temperature changes in the environment or heat generation accompanying rotation of the rotary shaft of the hydrostatic gas bearing spindle. Thereby, the position of the mounting surface changes. For example, Japanese Patent Application Laid-Open No. 2006-263824 (Patent Document 1) proposes a spindle device capable of suppressing a change in the position of the mounting surface due to thermal expansion.

  In the spindle device described in this publication, the housing is supported by the first support member and the second support member with respect to the floor surface. The second support member on the side far from the mounting surface has a parallel elastic spring. When the temperature of the housing rises due to the rotation of the main shaft, the housing is deformed so that its entire length becomes longer due to thermal expansion. At this time, the first support member on the side close to the mounting surface is hardly deformed. On the other hand, the second support member on the side far from the mounting surface is deformed by the deformation of the parallel elastic spring. For this reason, the mounting surface is mainly displaced in the direction of the second support member from the mounting surface along the axial direction of the housing.

JP 2006-263824 A

  However, in the spindle device described in the above publication, since the parallel elastic spring itself of the second support member has a certain degree of rigidity, all of the displacement of the housing due to thermal expansion is caused from the mounting surface to the second support member. It does not occur in the direction of That is, part of the displacement due to thermal expansion also occurs in the direction from the first support member to the mounting surface. As a result, the position of the mounting surface in the axial direction changes.

  Further, when the parallel elastic spring is deformed in the axial direction, the position of the parallel elastic spring in the height direction (direction intersecting the axial direction) is changed. Thereby, the position of the mounting surface in the height direction changes.

  Further, the second support member is deformed so that the position in the height direction is displaced by the parallel elastic spring, but the first support member is hardly deformed, so that the housing does not move parallel to the floor surface due to thermal expansion. . That is, since the housing is inclined with respect to the floor surface, the mounting surface is also inclined with respect to the floor surface.

  If the position of the mounting surface changes as described above, the position of the workpiece changes, so that it is difficult to perform highly accurate processing.

  This invention is made | formed in view of the said subject, The objective is to provide the static pressure gas bearing spindle which can suppress the change of the position of an attachment surface.

  The hydrostatic gas bearing spindle of the present invention is a hydrostatic gas bearing spindle fixed to an installation surface, and is supplied with a rotating shaft having a mounting surface on an end surface and a bearing gas for rotatably supporting the rotating shaft. A housing that surrounds the outer peripheral surface of the rotating shaft across the bearing gap, and first and second fixing bases that are arranged apart from each other in the axial direction of the housing and fix the housing to the installation surface ing. The 2nd fixed base arrange | positioned in the position away from the 1st fixed base with respect to the attachment surface contains the linear guide mechanism which can guide linearly to an axial direction.

  According to the static pressure gas bearing spindle of the present invention, the second fixed base arranged at a position away from the first fixed base with respect to the mounting surface includes the linear guide mechanism capable of linearly guiding in the axial direction. Therefore, the displacement of the housing due to thermal expansion can be guided linearly in the axial direction.

  For this reason, almost all the displacement of the housing in the axial direction caused by thermal expansion can be absorbed by the linear guide mechanism moving to the second fixed base side. Thereby, the change of the position of the attachment surface of an axial direction can be suppressed.

  Moreover, since the displacement of the housing due to thermal expansion can be linearly guided in the axial direction, it is possible to suppress the second fixing base from being deformed in the height direction. Thereby, the change of the position of the height direction of an attachment surface can be suppressed.

  Moreover, since it can suppress that a 2nd fixing stand deform | transforms in a height direction, a housing can be kept substantially parallel with respect to an installation surface by a 1st fixing stand and a 2nd fixing stand. . Therefore, the housing can move in parallel with respect to the installation surface. Thereby, it can suppress that an attachment surface inclines with respect to an installation surface.

  In the above hydrostatic gas bearing spindle, preferably, the second fixing base is a fixing member fixed to the installation surface, and a support attached to the housing and movable relative to the fixing member by a linear guide mechanism. Member. Thereby, the displacement of the housing due to thermal expansion can be linearly guided in the axial direction.

  In the above hydrostatic gas bearing spindle, the linear guide mechanism is preferably constituted by a linear guide. For this reason, the displacement of the housing due to thermal expansion can be linearly guided in the axial direction by the linear guide.

  In the above hydrostatic gas bearing spindle, preferably, the linear guide mechanism is constituted by a sliding bearing. For this reason, the displacement of the housing due to thermal expansion can be linearly guided in the axial direction by the sliding bearing.

  In the above-mentioned hydrostatic gas bearing spindle, the linear guide mechanism is preferably constituted by a hydrostatic gas bearing slide. For this reason, the displacement of the housing due to thermal expansion can be linearly guided in the axial direction by the static pressure gas bearing slide.

In the above hydrostatic gas bearing spindle, preferably, the second fixed base is made of a material having a coefficient of thermal expansion of 8 × 10 ⁻⁶ / K or less. For this reason, the change of the position of the attachment surface resulting from the thermal expansion of the 2nd fixed base can be suppressed.

  In the above-mentioned static pressure gas bearing spindle, preferably, the second fixed base further includes a flow path inside, and the second fixed base is configured to be cooled by flowing a gas through the flow path. . For this reason, the change of the position of the attachment surface resulting from the thermal expansion of the 2nd fixed stand can be suppressed by being cooled with gas.

  In the above hydrostatic gas bearing spindle, preferably, the second fixed base further includes a flow path inside, and the second fixed base is configured to be cooled by flowing a liquid through the flow path. . For this reason, the change of the position of the attachment surface resulting from the thermal expansion of the second fixing base can be suppressed by cooling with the liquid.

  In the above hydrostatic gas bearing spindle, preferably, the second fixed base further includes a cooling fin. For this reason, it is possible to suppress a change in the position of the mounting surface due to the thermal expansion of the second fixed base by being cooled by the cooling fins.

  As described above, according to the static pressure gas bearing spindle of the present invention, the change in the position of the mounting surface can be suppressed.

It is a schematic front view of the static pressure gas bearing spindle in Embodiment 1 and 2 of this invention. It is a schematic side view of the static pressure gas bearing spindle in Embodiment 1 of this invention. It is a schematic sectional drawing in alignment with the III-III line of FIG. It is a schematic front view which shows operation | movement of the static pressure gas bearing spindle in Embodiment 1 of this invention. It is a schematic partial front view which shows the vicinity of the linear guide mechanism of the modification 1 of the static pressure gas bearing spindle in Embodiment 1 of this invention. It is a schematic side view of the modification 1 of the static pressure gas bearing spindle in Embodiment 1 of this invention. It is a schematic exploded side view which shows the 2nd fixing stand of the modification 1 of the static pressure gas bearing spindle in Embodiment 1 of this invention. It is a schematic exploded side view which shows the 2nd fixing stand of the modification 2 of the static pressure gas bearing spindle in Embodiment 1 of this invention. It is a general | schematic fragmentary front view which shows the vicinity of the linear guide mechanism of the modification 3 of the static pressure gas bearing spindle in Embodiment 1 of this invention. It is a schematic side view of the modification 3 of the static pressure gas bearing spindle in Embodiment 1 of this invention. It is a schematic front view of the comparative example of the static pressure gas bearing spindle in Embodiment 1 of this invention. It is a schematic side view of the comparative example of the static pressure gas bearing spindle in Embodiment 1 of this invention. It is a schematic side view which shows the state which the housing of the comparative example of the static pressure gas bearing spindle in Embodiment 1 of this invention deform | transformed into the axial direction. It is a schematic side view which shows the state which the housing of the comparative example of the static pressure gas bearing spindle in Embodiment 1 of this invention deform | transformed to radial direction. It is a general | schematic fragmentary sectional view of the 2nd fixing stand of the modification 1 of the static pressure gas bearing spindle in Embodiment 2 of this invention. It is a general | schematic fragmentary sectional view of the 2nd fixing stand of the modification 2 of the static pressure gas bearing spindle in Embodiment 2 of this invention. It is a schematic side view which shows the state which the 1st and 2nd fixing stand of the comparative example of the static pressure gas bearing spindle in Embodiment 2 of this invention deform | transformed upward with respect to the installation surface.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(Embodiment 1)
First, the configuration of the static pressure gas bearing spindle according to the first embodiment of the present invention will be described.

  1 and 2, the static pressure gas bearing spindle of the present embodiment is a static pressure gas bearing spindle fixed to installation surface PS. The hydrostatic gas bearing spindle mainly has a rotating shaft 1, a housing 2, a first fixed base 3, and a second fixed base 4.

  The rotating shaft 1 has an attachment surface 1a to which a workpiece can be attached to the end surface. The housing 2 surrounds the outer peripheral surface of the rotating shaft 1 with a bearing gap (see FIG. 3) to which a bearing gas for rotatably supporting the rotating shaft 1 is supplied.

  The first fixing base 3 and the second fixing base 4 are arranged away from each other in the axis AX direction of the housing 2. The first fixing base 3 and the second fixing base 4 are each fixed to the housing 2 with fixing bolts 6a. The first fixing base 3 and the second fixing base 4 are also fixed to the installation surface PS by installation bolts 6b. The first fixing base 3 and the second fixing base 4 are for fixing the housing 2 to the installation surface PS.

  The second fixed base 4 is arranged at a position away from the first fixed base 3 with respect to the mounting surface 1a. The second fixed base 4 has a linear guide mechanism 5 capable of linearly guiding in the axis AX direction of the housing 2.

  The second fixing base 4 has a fixing member 41 and a support member 42. The fixing member 41 is fixed to the installation surface PS. The support member 42 is attached to the housing 2. The support member 42 can be moved relative to the fixed member 41 by the linear guide mechanism 5.

  The linear guide mechanism 5 may be any mechanism that can linearly guide in the direction of the axis AX of the housing 2. The linear guide mechanism 5 may be configured by a linear guide 51. The linear guide 51 includes a slider 51a, bearing balls 51b, and rails 51c. In FIG. 2, a bearing ball 51b is shown for convenience of explanation. The slider 51a is configured to be slidable with the rail 51c via a bearing ball 51b. The bearing ball 51b is rotatably held by the groove of the slider 51a and the groove of the rail 51c. The rail 51c is configured to extend in the axis AX direction of the housing 2.

  When the slider 51a slides along the rail 51c via the bearing ball 51b, the slider 51a can move linearly in the axis AX direction along the rail 51c. Since the slider 51a is connected to the support member 42 and the rail 51c is connected to the fixed member 41, the fixed member 41 and the support member 42 are relatively movable by the linear guide 51, and the direction of the axis AX It is possible to move linearly.

  Subsequently, the configuration of the static pressure gas bearing spindle of the present embodiment will be described in more detail. In FIG. 3, some components such as the rotating shaft are not shown in a cross-sectional view, but are shown in a plan view for easy viewing.

  With reference to FIG. 3, the rotating shaft 1 has a cylindrical shape. The rotation shaft 1 is configured to be rotatable about a rotation center axis CR. The rotation center axis CR is disposed so as to coincide with the axis AX of the housing 2. The rotating shaft 1 mainly has a table 11, a shaft spacer 12, and a thrust plate 13. The rotation center axes of the table 11, the shaft spacer 12, and the thrust plate 13 coincide with the rotation center axis CR of the rotation shaft 1. The table 11 is provided at one end of the rotating shaft 1. The end surface of the table 11 constitutes the end surface of the rotating shaft 1. A disc-shaped thrust plate 13 is provided on the table 11 with a shaft spacer 12 interposed therebetween.

  The housing 2 mainly includes a housing member 21, a bearing sleeve 22, a cooling jacket 23, and an encoder cover 24. The housing member 21 surrounds the outer periphery of the bearing sleeve 22 and holds the bearing sleeve 22. The housing member 21 includes a first housing member 21a disposed on the table 11 side, and a second housing member 21b disposed with the ring housing member 21c interposed between the first housing member 21a and the first housing member 21a.

  The bearing sleeve 22 surrounds the outer peripheral surface of the rotary shaft 1 with a bearing gap 10 to which a bearing gas for supporting the rotary shaft 1 rotatably is supplied. The bearing sleeve 22 is formed to face the surface (upper surface) on the table 11 side of the thrust plate 13 and the surface (lower surface) opposite to the table 11 with a bearing gap 10 therebetween. The bearing sleeve 22 includes a first bearing sleeve 22a held by the first housing member 21a and a second bearing sleeve 22b held by the second housing member 21b.

  The bearing sleeve 22 is formed with a nozzle 22 c for supplying bearing gas to the bearing gap 10. The nozzle 22 c is provided so that bearing gas can be supplied to the bearing gap 10 between each of the upper and lower surfaces of the thrust plate 13 and the bearing sleeve 22.

  The nozzle 22 c is connected to the bearing gas supply passage 31. The bearing gas supply passage 31 is connected to a bearing gas supply unit (not shown). The bearing gas is supplied through the bearing gas supply passage 31. For example, a pump may be applied as the bearing gas supply unit. The housing member 21 and the bearing sleeve 22 are formed with a bearing gas discharge path 32 that connects the bearing gap 10 and the outside of the housing 2. The bearing gas is discharged through the bearing gas discharge path 32.

  The bearing gas supplied from the bearing gas supply passage 31 is supplied from the nozzle 22 c to the bearing gap 10, so that the inner peripheral surface of the bearing sleeve 22 and the outer peripheral surface of the rotary shaft 1 have the diameter of the rotary shaft 1. It functions as a journal bearing (hydrostatic gas bearing for journal) 101 supported in the direction (radial direction).

  Further, the bearing gas supplied from the bearing gas supply passage 31 is supplied from the nozzle 22c to the bearing gap 10, so that the end surface of the bearing sleeve 22 and each of the upper surface and the lower surface of the thrust plate 13 are rotated. It functions as a thrust bearing (static pressure gas bearing for thrust) 102 that supports 1 in the axial direction (axial direction).

  In addition, a rotor 7 a connected so as to surround the outer peripheral surface of the rotating shaft 1 is disposed on the opposite side of the rotating shaft 11 from the table 11. A stator 7b is disposed so as to face the outer peripheral surface of the rotor 7a. The rotor 7a and the stator 7b constitute a motor 7 that rotationally drives the rotary shaft 1 around the rotation center axis CR. A driving force in the rotational direction is generated by the electromagnetic force between the rotor 7a and the stator 7b, and the rotation shaft 1 rotates around the rotation center axis CR. The motor 7 is covered with a motor cover 8.

  A cooling jacket 23 is provided so as to surround the housing member 21 and the motor cover 8. The cooling jacket 23 has a refrigerant supply port 33, a refrigerant flow path 34, and a refrigerant discharge port 35. The coolant or the cooling gas as the refrigerant supplied from the refrigerant supply port 33 is discharged from the refrigerant discharge port 35 through the refrigerant flow path 34. The entire static pressure gas bearing spindle is cooled by the flow of the refrigerant. As a result, the temperature of the static pressure gas bearing spindle can be stabilized. Moreover, the thermal expansion of the static pressure gas bearing spindle can be suppressed.

  The refrigerant flow path 34 is composed of a spirally processed groove or a plurality of annular grooves. For this reason, the cooling liquid or gas (refrigerant) reaches the entire refrigerant flow path 34 by supplying the refrigerant from one refrigerant supply port 33. When the coolant channel 34 is an annular groove, adjacent annular grooves may be connected by a groove formed in a direction perpendicular to the annular groove. The groove may be a single groove or a plurality of grooves.

  An encoder 9 is attached to the tip of the rotary shaft 11 on the side opposite to the table 11. An encoder cover 24 is provided so as to cover the encoder 9.

  With the above configuration, when compressed air, which is a bearing gas, is supplied from the bearing gas supply passage 31, the bearing gas flows from the nozzle 22c into the journal bearing portion 101 and the thrust bearing portion 102. And the bearing reaction force which balances with the dead weight of the rotating shaft 1, or an external load with the supply pressure of compressed air arises. For this reason, the rotating shaft 1 is rotationally driven around the rotation center axis CR while being supported by the housing 2 in a non-contact state.

Next, the operation of the static pressure gas bearing spindle of the present embodiment will be described.
Referring to FIG. 4, when thermal expansion occurs in the components of the static pressure gas bearing spindle due to the temperature change of the environment or the heat generated by the rotation of the rotary shaft 1 of the static pressure gas bearing spindle, the housing 2 becomes long. It deforms as follows. As a result, the housing 2 is displaced in the direction of the axis AX. In the static pressure gas bearing spindle of the present embodiment, the linear guide mechanism 5 moves in the direction of the axis AX and in the direction of the arrow X1 in accordance with the displacement of the housing caused by thermal expansion. Therefore, almost all of the displacement of the housing in the direction of the axis AX caused by thermal expansion is absorbed by the movement of the linear guide mechanism 5 in the direction of the arrow X1 in the drawing. Therefore, the change of the position of the attachment surface 1a is suppressed.

  Although the case where a linear guide is used as the linear guide mechanism 5 has been described above, a plain bearing may be used as the linear guide mechanism 5.

  With reference to FIGS. 5 to 7, in the first modification of the hydrostatic gas bearing spindle in the present embodiment, the linear guide mechanism 5 is configured by a sliding bearing 52. The slide bearing 52 includes a shaft member 52a, a bearing member 52b, and a lubricant 52c. The shaft member 52a has a tapered shape such that the area of the side surface decreases toward the bearing member 52b side. The bearing member 52b is configured to receive the tapered shape of the shaft member 52a. The bearing surface of the bearing member 52 b is configured to extend in the direction of the axis AX of the housing 2. A lubricant 52c is disposed between the shaft member 52a and the bearing member 52b.

  Since the shaft member 52a and the bearing member 52b relatively slide through the lubricant 52c, the shaft member 52a can move linearly along the bearing member 52b in the axis AX direction. Since the shaft member 52a is connected to the support member 42 and the bearing member 52b is connected to the fixed member 41, the fixed member 41 and the support member 42 are relatively movable by the sliding bearing 52, and the axis line It can move linearly in the AX direction.

  As the system of the sliding bearing 52, oil lubrication, paint having lubricity such as deflick coat, treatment having lubricity such as Teflon (registered trademark) coat, and the like can be applied.

  Further, the shape of the sliding bearing 52 is not limited to the shape of the first modification. In the second modification of the hydrostatic gas bearing spindle in the present embodiment, the shape of the sliding bearing 52 is different from the shape of the first modification. With reference to FIG. 8, in the second modification, the shaft member 52a and the bearing member 52b of the sliding bearing 52 are formed in a rectangular shape. The convex shape of the shaft member 52a is received in the concave shape of the bearing member 52b. In a state where the convex shape of the shaft member 52a is received in the concave shape of the bearing member 52b, the shaft member 52a and the bearing member 52b relatively slide through the lubricant 52c, so that the shaft member 52a is a bearing. It can move linearly in the axis AX direction along the member 52b.

Further, a static pressure gas bearing slide may be used as the linear guide mechanism 5.
With reference to FIG. 9 and FIG. 10, in the third modification of the hydrostatic gas bearing spindle in the present embodiment, the linear guide mechanism 5 is configured by a hydrostatic gas bearing slide 53. The static pressure gas bearing slide 53 has a stage portion 53a and a guide portion 53b. The stage portion 53a is configured to surround the outer peripheral surface of the guide portion 53b with a gap in a direction intersecting with the direction in which the guide portion 53b extends. A bearing gas is supplied to a gap between the stage portion 53a and the guide portion 53b from a bearing gas supply device (not shown). The stage portion 53a and the guide portion 53b are supported in a non-contact state by the bearing gas. The guide portion 53 b is configured to extend in the axis AX direction of the housing 2.

  The stage portion 53a linearly moves in the direction of the axis AX along the guide portion 53b by sliding along the guide portion 53b while being supported on the guide portion 53b in a non-contact state by the bearing gas. Can do. Since the stage portion 53 a is connected to the support member 42 and the guide portion 53 b is connected to the fixed member 41, the fixed member 41 and the support member 42 are relatively movable by the static pressure gas bearing slide 53. And linearly movable in the direction of the axis AX.

  Next, the effect of the static pressure gas bearing spindle of the present embodiment will be described in comparison with a comparative example.

  Referring to FIGS. 11 and 12, the static pressure gas bearing spindle of the comparative example of the present embodiment is mainly different from the static pressure gas bearing spindle of the present embodiment in that it does not have a linear guide mechanism. Is different. In the comparative example, the housing 2 is fixed to each of the first fixing base 3 and the second fixing base 4 fixed to the installation surface PS with the installation bolt 6b, with the fixing bolt 6a.

  Referring to FIG. 13, when the temperature of the housing 2 rises due to the temperature change of the environment or the heat generated by the rotation of the rotary shaft 1 of the hydrostatic gas bearing spindle, the housing 2 is deformed so that the entire length becomes longer due to thermal expansion. To do. That is, the housing 2 is deformed so as to extend in the axis AX direction and in the X1 direction and the X2 direction in the drawing. As a result, the mounting surface 1a is displaced in the axis AX direction by a distance D1 in the X2 direction in the drawing.

  At this time, since the temperature of the installation surface PS remains at room temperature and has not risen, thermal expansion does not occur at the lower ends of the first fixing table 3 and the second fixing table 4 that are in contact with the installation surface PS. . Therefore, the distance between each lower end of the 1st fixing stand 3 and the 2nd fixing stand 4 which touches the installation surface PS does not change. On the other hand, due to the thermal expansion of the housing 2, the distance between the upper ends of the first fixing base 3 and the second fixing base 4 fixed to the housing 2 by the fixing bolt 6a increases. Therefore, the first fixing base 3 and the second fixing base 4 are deformed with the thermal expansion of the housing 2.

  On the other hand, according to the hydrostatic gas bearing spindle of the present embodiment, the second fixed base arranged at a position away from the first fixed base with respect to the mounting surface is linearly guided in the axial direction. Since the possible linear guide mechanism is included, the displacement of the housing 2 due to thermal expansion can be linearly guided in the axial direction.

  For this reason, almost all of the displacement of the housing 2 in the direction of the axis AX caused by thermal expansion can be absorbed by the linear guide mechanism 5 moving to the second fixed base 4 side (in the direction of arrow X1 in the figure). Thereby, the change of the position of the attachment surface 1a of an axis line AX direction can be suppressed.

  Moreover, since the displacement of the housing due to thermal expansion can be linearly guided in the direction of the axis AX, it is possible to suppress the second fixing base 4 from being deformed in the height direction. Thereby, the change of the position of the attachment surface 1a in the height direction can be suppressed.

  Moreover, since it can suppress that the 2nd fixing stand 4 deform | transforms in a height direction, the housing 2 is substantially parallel with respect to the installation surface PS by the 1st fixing stand 3 and the 2nd fixing stand 4. Can be kept in. Therefore, the housing 2 can be translated with respect to the installation surface PS. Thereby, it can suppress that the attachment surface 1a inclines with respect to the installation surface PS.

  Since the change in the position of the attachment surface 1a can be suppressed as described above, the change in the position of the workpiece can be suppressed. Thereby, highly accurate processing can be performed.

  Also. According to the static pressure gas bearing spindle of the present embodiment, the second fixing base 4 is attached to the fixing member 41 fixed to the installation surface PS, the housing 2, and fixed to the fixing member 41 by the linear guide mechanism 5. And a support member 42 relatively movable. Thereby, the displacement of the housing 2 due to thermal expansion can be linearly guided in the direction of the axis AX.

  Further, according to the static pressure gas bearing spindle of the present embodiment, the linear guide mechanism 5 may be configured by the linear guide 51. Thereby, the displacement of the housing 2 due to thermal expansion can be linearly guided by the linear guide 51 in the direction of the axis AX.

  Further, according to the static pressure gas bearing spindle of the present embodiment, the linear guide mechanism 5 may be configured by the sliding bearing 52. Accordingly, the displacement of the housing 2 due to thermal expansion can be linearly guided by the sliding bearing 52 in the direction of the axis AX.

  Further, according to the static pressure gas bearing spindle of the present embodiment, the linear guide mechanism 5 may be constituted by the static pressure gas bearing slide 53. Thereby, the displacement of the housing 2 due to thermal expansion can be linearly guided in the axis AX direction by the static pressure gas bearing slide 53.

  Referring to FIG. 14, when the temperature of the housing 2 rises due to the temperature change of the environment or the heat generated by the rotation of the rotary shaft 1 of the static pressure gas bearing spindle, the housing 2 is in the radial direction (in the direction of arrow Y1 in the figure). ) To become larger. In this case, the housing 2 is deformed in the radial direction around the axis AX of the housing 2. Therefore, when the housing 2 and the first fixed base 3 and the second fixed base 4 are fixed at the position of the axis AX, the first fixed base 3 and the second fixed base are deformed by the radial deformation of the housing 2. 4 is not displaced in the height direction. Therefore, it is desirable that the positions of the fixing bolts 6a of the first fixing base 3 and the second fixing base 4 be the same height as the axis AX, and practically, the height is as close as possible to the axis AX. Is preferred.

(Embodiment 2)
Since the second embodiment of the present invention is the same as the configuration of the first embodiment described above unless otherwise described, the same elements are denoted by the same reference numerals, and the description thereof will not be repeated.

  In the first embodiment, the structure in which the displacement due to the thermal expansion is released in a direction that has no influence is described, but a structure that suppresses the displacement amount of the thermal expansion itself can also be applied.

Referring to FIG. 1 again, in the static pressure gas bearing spindle of the present embodiment, some or all of the components are made of a material (low thermal expansion material) having a low thermal expansion coefficient. More specifically, it is preferable that the first fixed base 3 and the second fixed base 4 are made of a material having a thermal expansion coefficient of 8 × 10 ⁻⁶ / K or less. In particular, it is preferable that the second fixing base 4 is made of a material having a thermal expansion coefficient of 8 × 10 ⁻⁶ / K or less. As a material having a thermal expansion coefficient of 8 × 10 ⁻⁶ / K or less, for example, invar, ceramic or the like can be applied.

  Moreover, the 1st fixing stand 3 and the 2nd fixing stand 4 may have a cooling mechanism. In particular, the second fixing base 4 preferably has a cooling mechanism.

  Referring to FIG. 15, the second fixed base 4 of the modified example 1 of the hydrostatic gas bearing spindle according to the present embodiment has a cooling mechanism that can be cooled by flowing a refrigerant therein. The 2nd fixed stand 4 has the supply port 4a, the flow path 4b, and the discharge port 4c. A supply port 4 a and a discharge port 4 c that open to the outside of the second fixing table 4 are arranged at both ends of a flow path 4 b provided inside the second fixing table 4.

  The gas or liquid as the refrigerant supplied from the supply port 4a is discharged from the discharge port 4c through the flow path 4b. The second fixing table 4 is cooled by flowing a gas or a liquid through the flow path 4b.

  The cooling mechanism may be a cooling fin. Referring to FIG. 16, the second fixed base 4 of Modification 2 of the hydrostatic gas bearing spindle of the present embodiment has cooling fins 4 d on the outer peripheral surface.

  Next, the effect of the static pressure gas bearing spindle of this embodiment will be described in comparison with a comparative example.

  Referring to FIG. 17, in the static pressure gas bearing spindle of the comparative example of the present embodiment, the first fixed base 3 and the heat generated by the temperature change of the environment or the rotation of the rotary shaft 1 of the static pressure gas bearing spindle The second fixed base 4 is deformed due to thermal expansion.

  When the first fixing base 3 and the second fixing base 4 are thermally expanded due to a temperature rise, the housing 2 is lifted upward (in the direction of arrow Y2 in the drawing) with respect to the installation surface PS due to thermal expansion. As a result, even when the first fixing base 3 and the second fixing base 4 are fixed at the position of the axis AX of the housing 2, the housing 2 is displaced upward by a distance D2. Thereby, since the attachment surface 1a is also displaced upwards, the position of the attachment surface 1a changes.

On the other hand, according to the static pressure gas bearing spindle of the present embodiment, the second fixed base 4 is made of a material having a thermal expansion coefficient of 8 × 10 ⁻⁶ / K or less. The thermal expansion of the table 4 can be suppressed. Thereby, the change of the position of the attachment surface 1a resulting from the thermal expansion of the 2nd fixing stand 4 can be suppressed.

  In addition, according to the static pressure gas bearing spindle of the present embodiment, the second fixed base 4 is configured to be cooled by flowing a gas through the flow path 4b, so that it is cooled by the gas. Therefore, the change in the position of the mounting surface 1a due to the thermal expansion of the second fixed base can be suppressed.

  Further, according to the static pressure gas bearing spindle of the present embodiment, the second fixed base 4 is configured to be cooled by flowing the liquid through the flow path 4b, and therefore is cooled by the liquid. Thus, the change in the position of the mounting surface 1a due to the thermal expansion of the second fixed base 4 can be suppressed.

  Also. According to the static pressure gas bearing spindle of the present embodiment, since the second fixed base 4 further includes the cooling fins 4d, the second fixed base 4 is thermally expanded by being cooled by the cooling fins 4d. The change of the position of the mounting surface 1a resulting from can be suppressed.

A low thermal expansion material and a cooling mechanism may be used in combination. That is, the cooling mechanism may be made of a material having a thermal expansion coefficient of 8 × 10 ⁻⁶ / K or less. Thereby, more stable performance can be exhibited.

Each of the above embodiments can be combined as appropriate.
The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  The invention can be applied particularly advantageously to hydrostatic gas bearing spindles that are fixed to the installation surface.

  DESCRIPTION OF SYMBOLS 1 Rotating shaft, 1a Mounting surface, 2 Housing, 3 1st fixing stand, 4 2nd fixing stand, 4a Supply port, 4b Flow path, 4c Discharge port, 4d Cooling fin, 5 Linear guide mechanism, 6a Fixing bolt, 6b Installation bolt, 7 Motor, 7a Rotor, 7b Stator, 8 Motor cover, 9 Encoder, 10 Bearing gap, 11 Table, 12 Shaft spacer, 13 Thrust plate, 21 Housing member, 21a First housing member, 21b Second housing member , 21c ring housing member, 22 bearing sleeve, 22a first bearing sleeve, 22b second bearing sleeve, 22c nozzle, 23 cooling jacket, 24 encoder cover, 31 bearing gas supply passage, 32 bearing gas discharge passage, 33 refrigerant Supply port, 34 Refrigerant flow path, 35 Refrigerant discharge port, 41 Fixing member 42 support member, 51 linear guide, 51a slider, 51b bearing ball, 51c rail, 52 slide bearing, 52a shaft member, 52b bearing member, 52c lubricant, 53 hydrostatic gas bearing slide, 53a stage portion, 53b guide portion, 101 journal bearing part, 102 thrust bearing part, CR rotation center axis, PS installation surface.

Claims (9)

A hydrostatic gas bearing spindle fixed to the installation surface,
A rotating shaft having a mounting surface on an end surface;
A housing that surrounds the outer peripheral surface of the rotary shaft across a bearing gap to which a bearing gas for rotatably supporting the rotary shaft is supplied;
A first and a second fixing base disposed apart from each other in the axial direction of the housing, and for fixing the housing to the installation surface;
A static pressure gas bearing spindle, comprising: a linear guide mechanism in which the second fixed base arranged at a position away from the first fixed base with respect to the mounting surface can linearly guide in the axial direction. The second fixing base is:
A fixing member fixed to the installation surface;
The hydrostatic gas bearing spindle according to claim 1, further comprising a support member attached to the housing and movable relative to the fixed member by the linear guide mechanism.   The hydrostatic gas bearing spindle according to claim 1 or 2, wherein the linear guide mechanism is constituted by a linear guide.   The hydrostatic gas bearing spindle according to claim 1 or 2, wherein the linear guide mechanism is a slide bearing.   The static pressure gas bearing spindle according to claim 1, wherein the linear guide mechanism is constituted by a static pressure gas bearing slide. The hydrostatic gas bearing spindle according to any one of claims 1 to 5, wherein the second fixed base is made of a material having a thermal expansion coefficient of 8 x ^10-6 / K or less. The second fixing base further includes a flow path inside,
The static pressure gas bearing spindle according to any one of claims 1 to 6, wherein the second fixed base is configured to be cooled by flowing a gas through the flow path. The second fixing base further includes a flow path inside,
The static pressure gas bearing spindle according to claim 1, wherein the second fixed base is configured to be cooled by flowing a liquid through the flow path.   The static pressure gas bearing spindle according to claim 1, wherein the second fixing base further includes a cooling fin.

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